Standards For The Metal

Products & Machinery

Point Source Category

2 Printed on paper containing at least 30% postconsumer recovered fiber.
Development Document 

For The Proposed Effluent Limitations 

Guidelines and Standards 

For The 

Metal Products & Machinery 

Point Source Category 

Carol M. Browner

Administrator

J. Charles Fox

Assistant Administrator, Office of Water

Geoffrey H. Grubbs

Director, Office of Science and Technology

Sheila E. Frace

Director, Engineering and Analysis Division

Marvin Rubin

Chief, Energy Branch

Shari Z. Barash

Project Manager

Michael C. Ebner

Assistant Project Manager

Lynne Tudor

Project Economist

Helen Jacobs

Project Statistician

December 2000

U.S. Environmental Protection Agency

Office of Water

Washington, DC 20460
ACKNOWLEDGMENTS AND DISCLAIMER

The Agency would like to acknowledge the contributions of Shari Barash, Mike

Ebner, Marvin Rubin, Helen Jacobs, Lynne Tudor, Karen Clark, and Beverly Randolph to

development of this technical document. In addition, EPA acknowledges the contribution

of Eastern Research Group, Westat, Abt Associates, and Science ApplicationsInternational

Corporation.

Neither the United States government nor any of its employees, contractors,

subcontractors, or other employees makes any warranty, expressed or implied, or assumes

any legal liability or responsibility for any third party’s use of, or the results of such use of,

any information, apparatus, product, or process discussed in thisreport, or representsthat its

use by such a third party would not infringe on privately owned rights.
i

TABLE OF CONTENTS

Page

1.0 SUMMARY AND SCOPE OF THE REGULATION ............................ 1-1

1.1 Overview of the MP&M Point Source Category .................. 1-1

1.2 Applicability of MP&M and Overlap with Other Effluent 

Guidelines ............................................... 1-3

1.3 Proposed Effluent Limitations Guidelines and Standards ........... 1-6

2.0 BACKGROUND ................................................... 2-1

2.1 Legal Authority ........................................... 2-1

2.2 Regulatory Background ..................................... 2-1

2.2.1 Clean Water Act ..................................... 2-1

2.2.2 Section 304(m) Requirements .......................... 2-4

2.2.3 Pollution Prevention Act .............................. 2-5

2.2.4 Regulatory Flexibility Act (RFA) as Amended by the Small

Business Regulatory Enforcement Fairness Act of 1996 

(SBREFA) ......................................... 2-5

2.2.5 Regulatory History of the Metals Industry ................. 2-7

3.0 DATA COLLECTION ACTIVITIES ...................................... 3-1

3.1 Industry Questionnaires ..................................... 3-1

3.1.1 The 1989 Industry Surveys ............................ 3-1

3.1.1.1 1989 Screener Survey ......................... 3-2

3.1.1.2 1989 Detailed Survey ......................... 3-7

3.1.2 The 1996 Industry Surveys ........................... 3-11

3.1.2.1 1996 Screener Surveys ....................... 3-12

3.1.2.2 1996 Long Detailed Survey ................... 3-14

3.1.2.3 1996 Short Detailed Survey ................... 3-18

3.1.2.4 1996 Municipality Detailed Survey ............. 3-20

3.1.2.5 1996 Federal Facilities Detailed Survey .......... 3-22

3.1.2.6 1997 Iron and Steel Industry Short Survey Data .... 3-23

3.1.2.7 1996 Publicly Owned Treatment Works (POTW)

Detailed Survey ............................. 3-24

3.2 Site Visits ............................................... 3-26

3.2.1 Criteria for Site Selection ............................. 3-26

3.2.2 Information Collected ............................... 3-28

3.3 Wastewater and Solid Waste Sampling ........................ 3-28

3.3.1 Criteria for Site Selection ............................. 3-29

3.3.2 Information Collected ............................... 3-30

3.3.3 Sample Collection and Analysis ....................... 3-30

3.4 Other Sampling Data ...................................... 3-37

3.5 Other Industry-Supplied Data ............................... 3-37
TABLE OF CONTENTS (Continued)

Page

ii

3.6 Other Data Sources ....................................... 3-38

3.6.1 EPA/EAD Databases ................................ 3-38

3.6.2 Fate of Priority Pollutants in Publicly Owned Treatment

Works Database .................................... 3-39

3.6.3 National Risk Management Research Laboratory (NRMRL)

Treatability Database ................................ 3-39

3.6.4 The Domestic Sewage Study .......................... 3-40

3.6.5 Toxics Release Inventory (TRI) Database ................ 3-40

3.7 References .............................................. 3-41

4.0 INDUSTRY DESCRIPTION ........................................... 4-1

4.1 Overview of the Industry .................................... 4-1

4.1.1 Number and Size of MP&M Sites ....................... 4-1

4.1.2 Geographic Distribution ............................... 4-2

4.1.3 Wastewater-Discharging Sites .......................... 4-3

4.1.4 Non-Wastewater-Discharging Sites ...................... 4-7

4.2 General Discussion of MP&M Processes ...................... 4-10

4.2.1 Types of Unit Operations Performed .................... 4-10

4.2.2 MP&M Unit Operations and Rinses .................... 4-13

4.2.3 Metal Types Processed ............................... 4-30

4.2.4 Wastewater Discharge Volumes Generated ............... 4-31

4.3 Trends in the Industry ..................................... 4-35

4.4 References .............................................. 4-35

5.0 WASTEWATER CHARACTERISTICS .................................... 5-1

5.1 Hexavalent Chromium-Bearing Wastewater ..................... 5-1

5.1.1 Unit Operations Generating Hexavalent Chromium-Bearing

Wastewater ......................................... 5-2

5.1.2 Chromium-Bearing Raw Wastewater Characteristics ........ 5-3

5.2 Cyanide-Bearing Wastewater ................................. 5-4

5.2.1 Unit Operations Generating Cyanide-Bearing Wastewater .... 5-4

5.2.2 Cyanide-Bearing Raw Wastewater Characteristics .......... 5-5

5.3 Oil-Bearing and Organic Pollutant-Bearing Wastewater ............ 5-6

5.3.1 Unit Operations Generating Oil-Bearing and/or Organic

Pollutant-Bearing Wastewater .......................... 5-6

5.3.2 Oil-Bearing and Organic Pollutant-Bearing Raw Wastewater

Characteristics ..................................... 5-16

5.4 Chelated Metal-Bearing Wastewater .......................... 5-20

5.4.1 Unit Operations Generating Chelated Metal-Bearing 

Wastewater ........................................ 5-20

5.4.2 Chelation-Breaking Raw Wastewater Characteristics ....... 5-20
TABLE OF CONTENTS (Continued)

Page

iii

5.5 General Metal-Bearing Wastewater ........................... 5-21

5.5.1 Unit Operations Generating General Metal-Bearing 

Wastewater ........................................ 5-21

5.5.2 General Metal-Bearing Raw Wastewater Characteristics .... 5-29

6.0 INDUSTRY SUBCATEGORIZATION .................................... 6-1

6.1 Methodology and Factors Considered for Basis of Subcategorization . 6-1

6.1.1 Factors Contributing to Subcategorization ................ 6-2

6.1.2 Factors That are not a Basis for MP&M Subcategorization ... 6-9

6.2 General Description of Facilities in Each Subcategory ............ 6-13

6.2.1 General Metals Subcategory .......................... 6-13

6.2.2 Metal Finishing Job Shops Subcategory ................. 6-14

6.2.3 Non-Chromium Anodizing Subcategory ................. 6-14

6.2.4 Printed Wiring Board Subcategory ..................... 6-15

6.2.5 Steel Forming and Finishing .......................... 6-15

6.2.6 Oily Wastes Subcategory ............................. 6-16

6.2.7 Railroad Line Maintenance Subcategory ................. 6-17

6.2.8 Shipbuilding Dry Dock Subcategory .................... 6-18

7.0 SELECTION OF POLLUTANT PARAMETERS .............................. 7-1

7.1 Identification of Pollutant Parameters of Concern ................. 7-3

7.2 Pollutants Proposed to be Regulated for Direct Dischargers ........ 7-13

7.2.1 Regulated Pollutant Analysis for Direct Dischargers in the

Metal-Bearing Subcategories .......................... 7-13

7.2.1.1 General Metals Subcategory .................. 7-20

7.2.1.2 Metal Finishing Job Shops Subcategory .......... 7-20

7.2.1.3 Non-Chromium Anodizing Subcategory ......... 7-20

7.2.1.4 Printed Wiring Board Subcategory .............. 7-21

7.2.1.5 Steel Forming and Finishing Subcategory ........ 7-21

7.2.2 Regulated Pollutant Analysis for Direct Dischargers in the

Oil-Bearing Subcategories ............................ 7-21

7.2.2.1 Oily Wastes Subcategory ..................... 7-26

7.2.2.2 Railroad Line Maintenance Subcategory ......... 7-27

7.2.2.3 Shipbuilding Dry Dock Subcategory ............ 7-27

7.3 Pollutants Proposed to be Regulated for Indirect Dischargers ....... 7-27

7.3.1 Pass-through Analysis for Indirect Dischargers ............ 7-28

7.3.2 Pass-through Analysis Results for Existing Sources ........ 7-31

7.3.3 Pass-through Analysis Results for New Sources ........... 7-32

7.4 References .............................................. 7-34
TABLE OF CONTENTS (Continued)

Page

iv

8.0 POLLUTION PREVENTION PRACTICES AND WASTEWATER TREATMENT

TECHNOLOGIES .................................................. 8-1

8.1 Pollution Prevention Practices ................................ 8-1

8.1.1 Flow Reduction Practices ............................. 8-1

8.1.1.1 Rinse Tank Design and Innovative Configurations . . 8-1

8.1.1.2 Additional Rinse Design Elements ............... 8-4

8.1.1.3 Rinse Water Use Control ...................... 8-5

8.1.1.4 Pollution Prevention for Process Baths ............ 8-6

8.1.2 In-Process Pollution Prevention Technologies ............. 8-7

8.1.2.1 Activated Carbon Adsorption ................... 8-7

8.1.2.2 Carbonate “Freezing” ......................... 8-8

8.1.2.3 Centrifugation and Pasteurization of Machining 

Coolants ................................... 8-8

8.1.2.4 Centrifugation and Recycling of Painting Water 

Curtains .................................... 8-9

8.1.2.5 Electrodialysis .............................. 8-11

8.1.2.6 Electrolytic Recovery ........................ 8-11

8.1.2.7 Evaporation ................................ 8-13

8.1.2.8 Filtration .................................. 8-13

8.1.2.9 Ion Exchange (in-process) ..................... 8-15

8.1.2.10 Reverse Osmosis ............................ 8-17

8.1.3 Other Types of Pollution Prevention Practices ............ 8-19

8.2 Preliminary Treatment of Segregated Wastewater Streams ......... 8-20

8.2.1 Chromium-Bearing Wastewater ....................... 8-20

8.2.2 Concentrated Metal-Bearing Wastewater ................ 8-22

8.2.3 Cyanide-Bearing Wastewater .......................... 8-22

8.2.3.1 Alkaline Chlorination ........................ 8-22

8.2.3.2 Ozone Oxidation ............................ 8-23

8.2.4 Chelated Metal-Bearing Wastewater .................... 8-24

8.2.4.1 Reduction to Elemental Metal ................. 8-24

8.2.4.2 Precipitation of an Insoluble Compound ......... 8-25

8.2.4.3 Physical Separation .......................... 8-26

8.2.5 Oil-Bearing Wastewater .............................. 8-26

8.2.5.1 Chemical Emulsion Breaking .................. 8-26

8.2.5.2 Oil Skimming .............................. 8-28

8.2.5.3 Flotation of Oils or Solids ..................... 8-31

8.2.5.4 Ultrafiltration .............................. 8-32

8.3 End-of-Pipe Wastewater and Sludge Treatment Technologies ...... 8-33

8.3.1 Metals Removal .................................... 8-33

8.3.1.1 Gravity Clarification for Solids Removal ......... 8-38

8.3.1.2 Microfiltration for Solids Removal .............. 8-40

8.3.2 Oil Removal ....................................... 8-41
TABLE OF CONTENTS (Continued)

Page

v

8.3.3 Polishing Technologies .............................. 8-41

8.3.3.1 Multimedia Filtration ........................ 8-41

8.3.3.2 Activated Carbon Adsorption .................. 8-42

8.3.3.3 Reverse Osmosis ............................ 8-43

8.3.3.4 Ion Exchange ............................... 8-43

8.3.4 Sludge Handling .................................... 8-43

8.3.4.1 Gravity Thickening .......................... 8-43

8.3.4.2 Pressure Filtration ........................... 8-44

8.3.4.3 Vacuum Filtration ........................... 8-45

8.3.4.4 Sludge Drying .............................. 8-47

8.4 References .............................................. 8-47

9.0 TECHNOLOGY OPTIONS ............................................ 9-1

9.1 Technology Evaluation Methods .............................. 9-1

9.2 Technology Options ........................................ 9-3

9.2.1 General Metals, Metal Finishing Job Shops, Printed Wiring 

Boards, Steel Forming and Finishing, and Non-Chromium 

Anodizing Subcategories ............................. 9-3

9.2.2 Oily Wastes Subcategory .............................. 9-7

9.2.3 Shipbuilding Dry Dock and Railroad Line Maintenance

Subcategories ....................................... 9-8

9.3 References ............................................... 9-9

10.0 LONG-TERM AVERAGES AND VARIABILITY FACTORS .................... 10-1

10.1 Sources of Technology Performance Data ...................... 10-2

10.1.1 EPA Sampling Program .............................. 10-2

10.1.2 Sampling Episodes Conducted by Industry and Local Sanitation

Districts .......................................... 10-3

10.1.3 Industry-Supplied Effluent Monitoring Data .............. 10-3

10.2 Evaluation of Treatment Effectiveness ........................ 10-4

10.2.1 Identification of Pollutants Not Present in the Raw 

Wastewater at Sufficient Concentrations to Evaluate 

Treatment Effectiveness .............................. 10-6

10.2.2 Assessment of General Treatment System Performance ..... 10-8

10.2.3 Identification of Process Upsets That Could Affect Data 

Quality .......................................... 10-10

10.2.4 Identification of Wastewater Treatment Chemicals ........ 10-12

10.3 Development of Long-Term Averages and Variability Factors ..... 10-12

10.3.1 Derivation of the Proposed Limitations ................. 10-12

10.3.2 Steps Used to Derive Concentration-Based Limitations .... 10-14

10.3.3 Modified Delta-Lognormal Model ..................... 10-14

10.3.4 Estimation Under the Modified Delta-Lognormal Model ... 10-16
TABLE OF CONTENTS (Continued)

Page

vi

10.3.5 Estimation of LTAs and VFs (Data Groups) ............. 10-17

10.3.6 Estimation of LTAs ................................ 10-17

10.3.7 Estimation of VFs ................................. 10-18

10.3.7.1 Estimation of 1-day VFs ................ 10-18

10.3.7.2 Estimation of 4-day VFs ................ 10-20

10.4 Methodology for Development of TOP Long-Term Averages and

Variability Factors ....................................... 10-23

11.0 COSTS OF TECHNOLOGY BASES FOR REGULATIONS ..................... 11-1

11.1 Summary of Costs ........................................ 11-2

11.2 Model Site Development ................................... 11-5

11.2.1 Site Selection ...................................... 11-5

11.2.2 Wastewater Stream Parameters ........................ 11-5

11.2.3 Pollutant Concentrations ............................. 11-6

11.2.4 Technology in Place ................................. 11-7

11.3 Methodology for Estimating Costs ........................... 11-9

11.3.1 Components of Cost ................................. 11-9

11.3.2 Sources and Standardization of Cost Data ............... 11-11

11.3.3 MP&M Design and Cost Model ...................... 11-13

11.3.4 General Assumptions Made During the Costing Effort ..... 11-19

11.4 Design and Costs of Individual Technologies .................. 11-23

11.4.1 Countercurrent Cascade Rinsing ...................... 11-23

11.4.2 Centrifugation and Pasteurization of Machining Coolant ... 11-30

11.4.3 Centrifugation of Painting Water Curtains .............. 11-30

11.4.4 Contract Hauling .................................. 11-31

11.4.5 Feed Systems ..................................... 11-32

11.4.6 Chemical Emulsion Breaking and Gravity Oil/Water 

Separation ....................................... 11-33

11.4.7 Dissolved Air Flotation ............................. 11-34

11.4.8 Ultrafiltration System for Oil Removal ................. 11-35

11.4.9 Batch Oil Emulsion Breaking with Gravity Flotation ...... 11-36

11.4.10 Chemical Reduction of Hexavalent Chromium ..... 11-36

11.4.11 Cyanide Destruction .......................... 11-37

11.4.12 Chemical Reduction/Precipitation of Chelated Metals 11-38

11.4.13 Chemical Precipitation ........................ 11-38

11.4.14 Slant-Plate Clarifier .......................... 11-39

11.4.15 Multimedia Filtration ......................... 11-40

11.4.16 Microfiltration for Solids Removal .............. 11-40

11.4.17 Sludge Thickening ........................... 11-41

11.4.18 Sludge Pressure Filtration ..................... 11-41

11.5 References ............................................. 11-42
TABLE OF CONTENTS (Continued)

Page

vii

12.0 POLLUTANT LOADING AND REDUCTION ESTIMATES ..................... 12-1

12.1 Estimation of Unit Operation Pollutant Concentrations ........... 12-3

12.1.1 Calculate Pollutant Concentrations for Each Sampling 

Point ............................................. 12-3

12.1.2 Estimate Pollutant Concentrations for Each Unit Operation . . 12-4

12.2 Calculation of Industry Pollutant Loadings and Reductions ........ 12-4

12.2.1 Industry Raw Wastewater Pollutant Loadings ............. 12-5

12.2.2 Industry Baseline Pollutant Loadings ................... 12-5

12.2.3 Option-Specific Industry Pollutant Loadings and Pollutant

Reductions ........................................ 12-6

13.0 NON-WATER QUALITY IMPACTS .................................... 13-1

13.1 Energy Requirements ...................................... 13-1

13.2 Air Emissions Impacts ..................................... 13-2

13.3 Solid Waste Generation .................................... 13-3

13.3.1 Wastewater Treatment Sludge ......................... 13-3

13.3.2 Waste Oil ......................................... 13-5

13.4 References .............................................. 13-6

14.0 EFFLUENT LIMITATIONS AND STANDARDS ............................ 14-1

14.1 Best Practicable Control Technology Currently Available (BPT) .... 14-1

14.1.1 BPT Technology Selection for General Metals 

Subcategory ....................................... 14-5

14.1.2 BPT Technology Selection for Metal Finishing Job Shops

Subcategory ....................................... 14-7

14.1.3 BPT Technology Selection for Non-Chromium Anodizing

Subcategory ...................................... 14-10

14.1.4 BPT Technology Selection for Printed Wiring Board 

Subcategory ...................................... 14-13

14.1.5 BPT Technology Selection for Steel Forming and

Finishing Subcategory .............................. 14-16

14.1.6 BPT Technology Selection for the Oily Wastes 

Subcategory ...................................... 14-25

14.1.7 BPT Technology Selection for the Railroad Line

Maintenance Subcategory ........................... 14-27

14.1.8 BPT Technology Selection for the Shipbuilding Dry Dock

Subcategory ...................................... 14-29

14.2 Best Conventional Pollutant Control Technology (BCT) ......... 14-31

14.2.1 BCT Option for Metal-Bearing Wastewater ............. 14-31

14.2.2 BCT Option for Oil-Bearing Wastewater ............... 14-32

14.3 Best Available Technology Economically Achievable (BAT) ..... 14-32

14.3.1 BAT Technology Selection for the General Metals 
TABLE OF CONTENTS (Continued)

Page

viii

Subcategory ...................................... 14-33

14.3.2 BAT Technology Selection for the Metal Finishing Job

Shops Subcategory ................................. 14-34

14.3.3 BAT Technology Selection for the Non-Chromium

Anodizing Subcategory ............................. 14-34

14.3.4 BAT Technology Selection for the Printed Wiring Board

Subcategory ...................................... 14-35

14.3.5 BAT Technology Selection for the Steel Forming and

Finishing Subcategory .............................. 14-35

14.3.6 BAT Technology Selection for the Oily Wastes 

Subcategory ...................................... 14-36

14.3.7 BAT Technology Selection for the Railroad Line

Maintenance Subcategory ........................... 14-36

14.3.8 BAT Technology Selection for the Shipbuilding Dry Dock

Subcategory ...................................... 14-37

14.4 Pretreatment Standards for Existing Sources (PSES) ............ 14-37

14.4.1 Overview of Options and Low-Flow Exclusions ......... 14-38

14.4.2 PSES for General Metals Subcategory ................. 14-40

14.4.3 PSES for the Metal Finishing Job Shops Subcategory ..... 14-44

14.4.4 PSES for the Non-Chromium Anodizing Subcategory ..... 14-48

14.4.5 PSES for the Printed Wiring Board Subcategory ......... 14-48

14.4.6 PSES for the Steel Forming and Finishing Subcategory .... 14-51

14.4.7 PSES for the Oily Wastes Subcategory ................. 14-58

14.4.8 PSES for the Railroad Line Maintenance Subcategory ..... 14-61

14.4.9 PSES for the Shipbuilding Dry Dock Subcategory ........ 14-61

14.5 New Source Performance Standards (NSPS) ................... 14-61

14.5.1 NSPS for the General Metals Subcategory .............. 14-62

14.5.2 NSPS for the Metal Finishing Job Shops Subcategory ..... 14-63

14.5.3 NSPS for the Non-Chromium Anodizing Subcategory ..... 14-66

14.5.4 NSPS for the Printed Wiring Board Subcategory ......... 14-67

14.5.5 NSPS for the Steel Forming and Finishing Subcategory .... 14-68

14.5.6 NSPS for the Oily Wastes Subcategory ................. 14-74

14.5.7 NSPS for the Railroad Line Maintenance Subcategory ..... 14-74

14.5.8 NSPS for the Shipbuilding Dry Dock Subcategory ........ 14-75

14.6 Pretreatment Standards for New Sources (PSNS) ............... 14-75

14.6.1 PSNS for the General Metals Subcategory .............. 14-76

14.6.2 PSNS for the Metal Finishing Job Shops Subcategory ..... 14-77

14.6.3 PSNS for the Non-Chromium Anodizing Subcategory .... 14-79

14.6.4 PSNS for the Printed Wiring Board Subcategory ......... 14-79

14.6.5 PSNS for the Steel Forming and Finishing Subcategory .... 14-80

14.6.6 PSNS for the Oily Wastes Subcategory ................. 14-86

14.6.7 PSNS for the Railroad Line Maintenance Subcategory ..... 14-86
TABLE OF CONTENTS (Continued)

Page

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14.6.8 PSNS for the Shipbuilding Dry Dock Subcategory ....... 14-86

15.0 PERMITTING GUIDANCE .......................................... 15-1

15.1 Background ............................................. 15-1

15.2 Implementing the MP&M Effluent Guidelines .................. 15-5

15.2.1 Application of the Building Block Approach for Direct 

Dischargers ........................................ 15-7

15.2.2 Application of the Combined Wastestream Formula for

Indirect Dischargers ................................ 15-10

15.2.3 Production-Based Limits for the Steel Forming and

Finishing Subcategory .............................. 15-12

15.2.4 Use of Site-Specific Historical Flow Data to Calculate 

Flow-Based Mass Limitations ........................ 15-15

15.2.5 Use of General MP&M Industry Flow Data to Develop

Flow-Based Mass Limitations ........................ 15-16

15.2.6 Estimating Reasonable Production Rates ............... 15-19

15.2.7 Monitoring Flexibility .............................. 15-24

15.3 Flow Guidance for Surface Treatment Rinsing Operations ........ 15-27

15.3.1 Identification of Sites With Pollution Prevention and

Water Conservation Practices ........................ 15-27

15.3.2 Influences on Flow Rates ............................ 15-38

15.3.3 Guidance for PNF Selection ......................... 15-39

15.4 Flow Guidance for Machining Operations ..................... 15-43

15.4.1 Identification of Sites With Pollution Prevention and

Water Conservation Practices ........................ 15-43

15.4.2 Influences on Flow Rates ............................ 15-48

15.4.3 Guidance for PNF Selection ......................... 15-49

15.5 Flow Guidance for Painting Operations ....................... 15-50

15.5.1 Identification of Sites With Pollution Prevention and

Water Conservation Practices ........................ 15-51

15.5.2 Influences on Flow Rates ............................ 15-56

15.5.3 Guidance for PNF Selection ......................... 15-57

15.6 Flow Guidance for Cleaning Operations ...................... 15-58

15.6.1 Identification of Sites With Pollution Prevention and

Water Conservation Practices ........................ 15-58

15.6.2 Influences on Flow Rates ............................ 15-63

15.6.3 Guidance for PNF Selection ......................... 15-65

15.7 References ............................................. 15-66

16.0 GLOSSARY/LIST OF ACRONYMS .................................... 16-1
x

LIST OF TABLES

Page

1-1 Clarification of Coverage by MP&M Subcategory ...................... 1-4

1-2 Typical Unit Operations Performed at MP&M Sites ..................... 1-7

2-1 Summary of Regulatory Levels of Control ............................ 2-4

2-2 Summary of Metals Industry Effluent Guidelines ....................... 2-7

3-1 1989 and 1996 MP&M Survey Mailout Results ........................ 3-4

3-2 Summary of 1996 Detailed Survey Information by Question Number ...... 3-16

3-3 Number of Sites Visited Within Each MP&M Sector ................... 3-26

3-4 Number of Sites Sampled Within Each MP&M Sector .................. 3-29

3-5 Metal Constituents Measured Under the MP&M Sampling Program ....... 3-32

3-6 Organic Constituents Measured Under the MP&M Sampling Program ..... 3-33

3-7 Additional Parameters Measured Under the MP&M Sampling Program .... 3-36

4-1 MP&M Wastewater-Discharging Sites by Sector ....................... 4-4

4-2 MP&M Unit Operations Listed by Type ............................. 4-12

4-3 Typical Unit Operations Performed at MP&M Sites .................... 4-14

4-4 Additional Water-Using Unit Operations Performed at MP&M Sites ...... 4-30

4-5 Number of MP&M Sites Discharging Process Wastewater by Unit Operation

and Flow ..................................................... 4-32

5-1 Number of Process and Rinse Samples for Unit Operations That Generate

Hexavalent Chromium-Bearing Wastewater ........................... 5-2

5-2 Summary of Analytical Data for Chromium From Unit Operations and Rinses

Generating Chromium-Bearing Wastewater ........................... 5-3

5-3 Summary of Analytical Data for Chromium in Chromium-Bearing Raw 

Wastewater at Influent to Hexavalent Chromium Treatment .............. 5-3
LIST OF TABLES (Continued)

Page

xi

5-4 Number of Process and Rinse Samples for Unit Operations That Generate 

Cyanide-Bearing Wastewater ....................................... 5-4

5-5 Summary of Analytical Data for Cyanide from Unit Operations and Rinses

Generating Cyanide-Bearing Wastewater ............................. 5-5

5-6 Summary of Analytical Data for Cyanide in Cyanide-Bearing Raw

Wastewater at Influent to Cyanide Treatment .......................... 5-5

5-7 Number of Process and Rinse Samples For Unit Operations That Generate

Oil-Bearing and/or Organic Pollutant-Bearing Wastewater ............... 5-7

5-8 Analytical Data for Unit Operations Generating Oil-Bearing and/or

Organic-Bearing Wastewater ....................................... 5-8

5-9 Analytical Data for Rinses Generating Oil-Bearing and/or Organic-Bearing

Wastewater .................................................... 5-13

5-10 Analytical Data for Oil-Bearing and Organic Pollutant-Bearing Raw

Wastewater Streams at Influent to Oil/Water Separation ................ 5-16

5-11 Number of Process and Rinse Samples From Unit Operations That Generate

General Metal-Bearing Wastewater ................................. 5-22

5-12 Analytical Data from Unit Operations Generating General Metal-Bearing

Wastewater .................................................... 5-23

5-13 Analytical Data from Rinses Generating General Metal-Bearing Wastewater 5-27

5-14 Analytical Data for General Metal-Bearing Treatment Influent Wastewater 

Streams ....................................................... 5-31

6-1 Proposed Subcategories .......................................... 6-2

6-2 Percentage of Facilities Using Multiple Metal Types by Subcategory ....... 6-4

6-3 Percentage of MP&M Facilities by Subcategory Using Each Metal Type .... 6-6

6-4 Unit Operations Performed by Oily Wastes Facilities .................... 6-8

7-1 Priority Pollutant List ............................................. 7-2
LIST OF TABLES (Continued)

Page

xii

7-2 Pollutant Parameters Not Detected in Any Samples Collected During the

MP&M Sampling Program ........................................ 7-5

7-3 Pollutant Parameters Detected in Less Than Three Samples Collected

During the MP&M Sampling Program ............................... 7-7

7-4 Pollutant Parameters Detected at Average Concentrations of Less Than Five 

Times the Minimum Level During the MP&M Sampling Program ......... 7-8

7-5 Pollutant Parameters Selected for Further Consideration Under the MP&M

Proposed Rule .................................................. 7-9

7-6 Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Controlled Through the Regulation of

Other Pollutants ................................................ 7-14

7-7 Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Present in Only Trace Amounts and/or Are

Not Likely to Cause Toxic Effects .................................. 7-15

7-8 Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They May Serve as Treatment Chemicals in the

MP&M Industry ................................................ 7-16

7-9 Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Not Controlled by the Selected BPT/BAT

Technology ................................................... 7-17

7-10 64 Remaining Pollutants Considered for Proposed Regulation for the MetalBearing Subcategories ........................................... 7-18

7-11 Pollutants Not Selected for Proposed Regulation for the Oil-Bearing 

Subcategories Because They Are Controlled Through the Regulation of

Other Pollutants ................................................ 7-22

7-12 Pollutants Not Selected for Proposed Regulation for the Oil-Bearing 

Subcategories Because They Are Present in Only Trace Amounts and/or Are

Not Likely to Cause Toxic Effects .................................. 7-23

7-13 Pollutants Not Selected for Proposed Regulation for the Oil-Bearing 

Subcategories Because They May Serve as Treatment Chemicals in the

MP&M Industry ................................................ 7-24
LIST OF TABLES (Continued)

Page

xiii

7-14 Pollutants Not Selected for Proposed Regulation for the Oil-Bearing 

Subcategories Because They Are Not Controlled by the Selected BPT/BAT

Technology .................................................... 7-25

7-15 49 Remaining Pollutants Considered for Proposed Regulation for the OilBearing Subcategories ........................................... 7-25

7-16 Pass-Through Analysis Results for Existing Sources for Metal-Bearing 

Wastewater Subcategories ........................................ 7-31

7-17 Pass-Through Analysis Results for New Sources for Metal-Bearing

Wastewater Subcategories ........................................ 7-33

9-1 EMH Tier 1 - MP&M Source Reduction and Pollution Prevention 

Technologies .................................................. 9-10

9-2 EMH Tier 2 - MP&M Recycling Technologies ........................ 9-13

9-3 EMH Tiers 3 and 4 - MP&M End-of-Pipe Treatment and Disposal 

Technologies .................................................. 9-15

9-4 Technology Options by Subcategory ................................ 9-20

10-1 Number of Evaluated Treatment Systems for Each Subcategory ......... 10-24

10-2 Influent and Effluent Data Points from EPA Sampling Episodes ......... 10-25

10-3 Influent and Effluent Data Points from Industry and Local Sanitation

District Sampling Episodes ...................................... 10-26

10-4 Industry-Supplied Effluent Monitoring Data ......................... 10-26

10-5 Number of Effluent Data Points Flagged for Each MP&M Technology 

Option ...................................................... 10-27

10-6A MP&M Technology Effectiveness Concentrations for Total and Amenable

Cyanide Destruction ............................................ 10-28

10-6B MP&M Technology Effectiveness Concentrations for General Metals and

Steel Forming and Finishing Subcategories (Option 2) ................. 10-29
LIST OF TABLES (Continued)

Page

xiv

10-6C MP&M Technology Effectiveness Concentrations for General Metals and

Steel Forming and Finishing Subcategory (Option 4) .................. 10-33

10-6D MP&M Technology Effectiveness Concentrations for Metal Finishing Job

Shops Subcategory (Option 2) .................................... 10-34

10-6E MP&M Technology Effectiveness Concentrations for Nonchromium

Anodizers Subcategory (Option 2) ................................. 10-36

10-6F MP&M Technology Effectiveness Concentrations for Printed Wiring

Boards Subcategory (Option 2) ................................... 10-36

10-6G MP&M Technology Effectiveness Concentrations for Printed Wiring

Boards Subcategory (Option 4) ................................... 10-37

10-6H MP&M Technology Effectiveness Concentrations for Oily Wastes

Subcategory (Option 6) ......................................... 10-37

10-6I MP&M Technology Effectiveness Concentrations for Railroad Line

Maintenance Subcategory (Option 10) ............................. 10-38

10-6J MP&M Technology Effectiveness Concentrations for Shipbuilding and

Drydock Subcategory (Option 10) ................................. 10-39

10-7 Calculation of Total Organics Parameter (TOP) Limit ................. 10-40

10-8A Episode-Level Long-Term Averages and Variability Factors for Total

and Amenable Cyanide Destruction (All Options for Applicable 

Subcategories) ................................................ 10-42

10-8B Episode-Level Long-Term Averages and Variability Factors for

General Metals and Steel Forming and Finishing Subcategories 

(Option 2) .................................................... 10-43

10-8C Episode-Level Long-Term Averages and Variability Factors for

General Metals and Steel Forming and Finishing Subcategories (Option 4) . 10-47

10-8D Episode-Level Long-Term Averages and Variability Factors for

Metal Finishing Job Shops Subcategory (Option 2) ................... 10-49

10-8E Episode-Level Long-Term Averages and Variability Factors for

Metal Finishing Job Shops (Option 4) .............................. 10-51
LIST OF TABLES (Continued)

Page

xv

10-8F Episode-Level Long-Term Averages and Variability Factors for

Nonchromium Anodizing Subcategory (Option 2) .................... 10-53

10-8G Episode-Level Long-Term Averages and Variability Factors for

Printed Wiring Boards Subcategory (Option 2) ....................... 10-55

10-8H Episode-Level Long-Term Averages and Variability Factors for

Printed Wiring Boards Subcategory (Option 4) ....................... 10-57

10-8I Episode-Level Long-Term Averages and Variability Factors for

 Oily Waste Subcategory (Option 6) ............................... 10-58

10-8J Railroad Line Maintenance Subcategory (Option 10) .................. 10-59

10-8K Shipbuilding Dry Dock Subcategory (Option 10) ..................... 10-59

10-9A Pollutant-Level Long-term Averages, Variability Factors and Limitations

for General Metals Option 2 ..................................... 10-60

10-9B Pollutant-Level Long-term Averages, Variability Factors and Limitations

for General Metals Subcategory (Option 4) .......................... 10-61

10-9C Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Metal Finishing Job Shops Subcategory (Option 2) ................. 10-62

10-9D Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Metal Finishing Job Shops Subcategory (Option 4) ................. 10-63

10-9E Pollutant-Level Long-term Averages, Variability Factors and Limitations 

for Non-Chromium Anodizing Subcategory (Option 2) ................ 10-64

10-9F Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Printed Wiring Boards (Option 2) .............................. 10-65

10-9G Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Printed Wiring Boards (Option 4) .............................. 10-66

10-9H Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Oily Wastes Subcategory (Option 6) ........................ 10-67

10-9I Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Railroad Line Maintenance Subcategory (Option 10) ............... 10-67
LIST OF TABLES (Continued)

Page

xvi

10-9J Pollutant-Level Long-term Averages, Variability Factors and Limitations

for Shipbuilding Dry Docks Subcategory (Option 10) ................. 10-68

11-1 MP&M Total Estimated Annualized Costs at the Proposed Options for

Existing Sources ................................................ 11-4

11-2 Components of Total Capital Investment ........................... 11-10

11-3 RSMeans Building Construction Historical Cost Indexes ............... 11-13

11-4 Contract-Hauling Costs for Various Waste Types ..................... 11-13

11-5 Wastewater Treatment Technologies and Source Reduction and Recycling

Practices for Which EPA Developed Cost Modules ................... 11-14

11-6 List of Unit Operations Feeding Each Treatment Unit or In-Process 

Technology .................................................. 11-15

11-7 Sedimentation and Oil Treatment Technologies Considered Treatment in 

Place for Various Technology Options ............................. 11-21

11-8 MP&M Equipment Cost Equations ................................ 11-25

12-1 Summary of Annual Pollutant Loadings for MP&M Direct Dischargers by

Subcategory ................................................... 12-8

12-2 Summary of Annual Pollutant Loadings for MP&M Indirect Dischargers by

Subcategory ................................................... 12-9

12-3 Publicly Owned Treatment Works (POTW) Removal Percents For Each

MP&M Pollutants of Concern .................................... 12-10

12-4 Summary of Annual Pollutant Reductions for MP&M Direct Dischargers

by Subcategory ............................................... 12-15

12-5 Summary of Annual Pollutant Reductions for MP&M Indirect Dischargers

by Subcategory ................................................ 12-16

12-6 Top Pollutants Removed by Proposed Option for General Metals Direct

Dischargers ................................................... 12-17
LIST OF TABLES (Continued)

Page

xvii

12-7 Top Pollutants Removed by Proposed Option for Metal Finishing Job

Shops Direct Dischargers ........................................ 12-19

12-8 Top Pollutants Removed by Proposed Option for Printed Wiring Board

Direct Dischargers ............................................. 12-21

12-9 Top Pollutants Removed by Proposed Option for Steel Forming

and Finishing Direct Dischargers .................................. 12-22

12-10 Top Pollutants Removed by Proposed Option for Oily Wastes Direct 

Dischargers ................................................... 12-24

12-11 Top Pollutants Removed by Proposed Option for Railroad Line

Maintenance Direct Dischargers .................................. 12-25

12-12 Top Pollutants Removed by Proposed Option for Shipbuilding Dry Dock

Direct Dischargers ............................................. 12-26

12-13 Top Pollutants Removed by Proposed Option for General Metals Indirect

Dischargers ................................................... 12-27

12-14 Top Pollutants Removed by Proposed Option for Metal Finishing

Job Shops Indirect Dischargers ................................... 12-29

12-15 Top Pollutants Removed by Option 2 for Non-Chromium Anodizing

Indirect Dischargers ............................................ 12-31

12-16 Top Pollutants Removed by Proposed Option for Printed Wiring Board

Indirect Dischargers ............................................ 12-32

12-17 Top Pollutants Removed by Proposed Option for Steel Forming

and Finishing Indirect Dischargers ................................ 12-33

12-18 Top Pollutants Removed by Proposed Option for Oily Wastes Indirect

Dischargers ................................................... 12-35

12-19 Top Pollutants Removed by Option 10 for Railroad Line Maintenance

Indirect Dischargers ............................................ 12-36

12-20 Top Pollutants Removed by Option 10 for Shipbuilding Dry Dock

Indirect Dischargers ............................................ 12-37
LIST OF TABLES (Continued)

Page

xviii

13-1 Energy Usage by Option ......................................... 13-1

13-2 Wastewater Treatment Sludge by Option ............................ 13-4

13-3 Waste Oil Removed by Option .................................... 13-6

14-1 Pounds of Pollutants Removed by the Proposed BPT Option for Direct

Dischargers by Subcategory ....................................... 14-3

14-2 Annualized Costs and Economic Impacts of the Proposed BPT Option for 

Direct Dischargers by Subcategory ................................. 14-4

14-3 BPT/BAT Effluent Limitations for the General Metals Subcategory ....... 14-7

14-4 BPT/BAT Effluent Limitations for the Metal Finishing Job Shops 

Subcategory .................................................. 14-10

14-5 BPT/BAT Effluent Limitations for the Non-Chromium Anodizing 

Subcategory .................................................. 14-13

14-6 BPT/BAT Effluent Limitations for the Printed Wiring Board Subcategory . 14-15

14-7 Production Normalized Flows (PNF) for Steel Forming and Finishing .... 14-18

14-8 BPT/BAT Effluent Limitations for the Steel Forming and Finishing 

Subcategory .................................................. 14-21

14-9 BPT/BAT Effluent Limitations for the Oily Wastes Subcategory ......... 14-27

14-10 BPT Effluent Limitations for the Railroad Line Maintenance Subcategory . 14-29

14-11 BPT Effluent Limitations for the Shipbuilding Dry Dock Subcategory .... 14-30

14-12 Annual Pounds of Pollutants Removed by the Proposed PSES Option for

Indirect Dischargers by Subcategory ............................... 14-39

14-13 Annual Costs and Economic Impacts of the Proposed PSES Option for

Indirect Dischargers by Subcategory ............................... 14-40

14-14 PSES for the General Metals Subcategory ........................... 14-43

14-15 PSES for the Metal Finishing Job Shops Subcategory ................. 14-47
LIST OF TABLES (Continued)

Page

xix

14-16 PSES for the Printed Wiring Board Subcategory ..................... 14-50

14-17 PSES for the Steel Forming and Finishing Subcategory ................ 14-53

14-18 PSES for the Oily Wastes Subcategory ............................. 14-60

14-19 NSPS for the General Metals Subcategory .......................... 14-63

14-20 NSPS for the Metal Finishing Job Shops Subcategory ................. 14-65

14-21 NSPS for the Non-Chromium Anodizing Subcategory ................. 14-67

14-22 NSPS for the Printed Wiring Board Subcategory ..................... 14-68

14-23 NSPS for the Steel Forming and Finishing Subcategory ................ 14-70

14-24 PSNS for the General Metals Subcategory .......................... 14-77

14-25 PSNS for Metal Finishing Job Shops Subcategory .................... 14-78

14-26 PSNS for the Printed Wiring Board Subcategory ..................... 14-80

14-27 PSNS for the Steel Forming and Finishing Subcategory ................ 14-81

15-1 (a) Descriptive Statistics of MP&M Survey Data for Unit Operations with

Square Feet as the Production-Normalizing Parameter ................. 15-68

15-1 (b) Descriptive Statistics of MP&M Survey Data for Unit Operations with

Pounds of Metal Removed as the Production-Normalizing Parameter ..... 15-73

15-2 Water Conservation Methods for Surface Treatment Rinses ............. 15-74

15-3 Definitions of Pollution Prevention and Water Conservation Practices and

Technologies ................................................. 15-76

15-4 Factors Affecting Drag-Out ...................................... 15-81

15-5 Rinse-water Required for Various Plating Processes Based on Literature 

Values ...................................................... 15-82

15-6 Adjusted Production-Normalized Flow (PNF) Data for Countercurrent

Cascade-Rinses ............................................... 15-87
LIST OF TABLES (Continued)

Page

xx

15-7 Pollution Prevention and Water Conservation Methods Applicable to

Machining Operations .......................................... 15-88

15-8 Pollution Prevention and Water Conservation Methods Applicable to

Painting Operations ............................................ 15-90

15-9 Pollution Prevention and Water Conservation Methods Applicable to

Cleaning Operations ............................................ 15-91
xxi

LIST OF FIGURES

Page

3-1 Percentage of 1989 and 1996 MP&M Surveys Returned and Percentage of

Survey Respondents Engaged in MP&M Unit Operations ................ 3-5

3-2 Number of MP&M Sites Visited and Sampled by Industrial Sector ........ 3-27

4-1 MP&M Wastewater-Discharging Sites by Number of Employees and

Estimated Total Discharge Flow .................................... 4-2

4-2 Estimated Number of MP&M Facilities by EPA Region ................. 4-3

4-3 MP&M Wastewater-Discharging Sites and Total Discharge Flow by 

Activity ........................................................ 4-5

4-4 MP&M Wastewater-Discharging Sites and Total Discharge Flow by

Discharge Status ................................................. 4-6

4-5 MP&M Wastewater-Discharging Sites by Total Discharge Flow ........... 4-7

4-6 Number of Screener Survey Respondents Utilizing Each Zero Discharge 

Method ........................................................ 4-9

4-7 Number of MP&M Wastewater-Discharging Sites by Number of Metal

Types Processed ................................................ 4-31

6-1 Percentage of Wastewater-Discharging Facilities by Decade Built ......... 6-10

8-1 Countercurrent Cascade Rinsing .................................... 8-2

8-2 Machine Coolant Recycling System ................................. 8-9

8-3 Centrifugation and Recycling of Painting Water Curtains ............... 8-10

8-4 Electrodialysis Cell ............................................. 8-11

8-5 Membrane Filtration Unit ........................................ 8-14

8-6 Ion Exchange .................................................. 8-15

8-7 Chemical Reduction of Hexavalent Chromium ........................ 8-21

8-8 Cyanide Destruction Through Alkaline Chlorination ................... 8-23
LIST OF FIGURES (Continued)

Page

xxii

8-9 Chemical Reduction / Precipitation of Chelated Metals ................. 8-25

8-10 Continuous Chemical Emulsion Breaking Unit with Coalescing Plates ..... 8-27

8-11a Disc Oil Skimming Unit ......................................... 8-29

8-11b Belt Oil Skimming Unit ......................................... 8-30

8-12 Dissolved Air Flotation Unit ...................................... 8-32

8-13 Continuous Chemical Precipitation System with Lamella Clarifier ........ 8-35

8-14 Effect of pH on Hydroxide and Sulfide Precipitation ................... 8-36

8-15 Clarifier ...................................................... 8-39

8-16 Multimedia Filtration System ..................................... 8-42

8-17 Gravity Thickening ............................................. 8-44

8-18 Plate-and-Frame Filter Press ...................................... 8-45

8-19 Rotary Vacuum Filter ............................................ 8-46

9-1 End-of-Pipe Treatment Train for Options 1 and 2 Considered for the 

Following Subcategories: General Metals, Metal Finishing Job Shops, NonChromium Anodizing, Printed Wiring Boards, and Steel Forming and 

Finishing ..................................................... 9-21

9-2 In-Process Water Use Reduction Technologies for Options 2 and 4 

Considered for the Following Subcategories: General Metals, Metal 

Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Boards, 

and Steel Forming and Finishing ................................... 9-22

9-3 End-of-Pipe Treatment Train for Options 3 and 4 Considered for the 

Following Subcategories: General Metals, Metal Finishing Job Shops, NonChromium Anodizing, Printed Wiring Boards, and Steel Forming and 

Finishing ..................................................... 9-23

9-4 End-of-Pipe Treatment Train for Options 5 and 6 Considered for the Oily

Wastes Subcategory ............................................. 9-24
LIST OF FIGURES (Continued)

Page

xxiii

9-5 End-of-Pipe Treatment Train for Option 7 and 8 Considered for the 

Following Subcategories: Oily Wastes, Railroad Line Maintenance, 

Shipbuilding Dry Dock .......................................... 9-25

9-6 End-of-Pipe Treatment Train for Options 9 and 10 Considered for the 

Railroad Line Maintenance and Shipbuilding Dry Dock Subcategories ..... 9-26

10-1 Summary of Technology Performance Data-Editing Procedures .......... 10-5

10-2 Modified Delta-Lognormal Model ................................. 10-15

11-1 Relationship Between In-Process and End-of-Pipe Technologies and 

Practices ..................................................... 11-43

11-2 Components of Total Capital Investment ........................... 11-44

11-3 Logic Used to Apply End-of-Pipe Technologies and Practices for the

Following Subcategories: General Metals, Metal Finishing Job Shops,

Non-Chromium Anodizing, Printed Wiring Board, and Steel Forming and

Finishing .................................................... 11-45

11-4 Logic Used to Apply End-of-Pipe Technologies and Practices for the

Following Subcategories: Oily Waste, Railroad Line Maintenance, and

Shipbuilding Dry Dock ......................................... 11-46

12-1 Estimates of MP&M Pollutant Loadings and Reductions ................ 12-2

15-1 MP&M Permitting Process Flow Chart .............................. 15-8

15-2a Single Rinse Tank ............................................. 15-35

15-2b Single Rinse Tank with Flow Reduction ............................ 15-35

15-2c Multiple Rinse Tanks with Flow Reduction ......................... 15-36

15-2d Countercurrent Rinsing with Flow Reduction ........................ 15-36

15-2e Multiple Rinse Tanks with Flow Reduction and Drag-Out Recovery ...... 15-37

15-2f Multiple Rinse Tanks with Water Recycle, Drag-Out Recovery, and Metal

Recovery .................................................... 15-37
1.0 - Summary and Scope of the Regulation

1-1

1.0 SUMMARY AND SCOPE OF THE REGULATION

Pursuant to the Clean Water Act (CWA), EPA is proposing effluent limitations

guidelines and standards for the Metal Products and Machinery (MP&M) Point Source Category. 

This document and the administrative record for this rulemaking provide the technical basis for

these effluent limitations guidelines and pretreatment standards. Direct discharging facilities

discharge wastewater to a surface water (e.g., lake, river, ocean). Indirect discharging facilities

discharge wastewater to a publicly owned treatment works (POTW).

Section 1.1 presents an overview of the MP&M Point Source Category. Section

1.2 describes the applicability of the MP&M proposal and how it overlaps with previously

promulgated metals regulations. Section 1.3 summarizes the proposed effluent limitations

guidelines and standards.

1.1 Overview of the MP&M Point Source Category

The MP&M Point Source Category includes sites that generate wastewater as a

result of processing metal parts, metal products, and machinery. Although facilities in the MP&M

industry produce a wide range of products, the operations performed can be described by two

types of activities: manufacturing, and rebuilding/maintenance. Manufacturing is the series of unit

operations necessary to produce metal products, and is generally performed in a production

environment. Rebuilding/maintenance is the series of unit operations necessary to disassemble

used metal products into components, replace the components or subassemblies or restore them to

original function, and reassemble the metal product. These operations are intended to keep metal

products in operating condition and can be performed in either a production or a non-production

environment. These manufacturing and rebuilding/maintenance activities occur in industrial

sectors including:

C Aerospace;

C Aircraft;

C Bus and Truck; 

C Electronic Equipment;

C Hardware;

C Household Equipment;

C Instruments;

C Job Shops;

C Mobile Industrial Equipment;

C Motor Vehicle;

C Office Machine;

C Ordnance; 

C Precious Metals and Jewelry;

C Printed Wiring Boards;

C Railroad;

C Ships and Boats;

C Stationary Industrial Equipment; and
1.0 - Summary and Scope of the Regulation

1-2

C Miscellaneous Metal Products.

EPA has identified these 18 industrial sectors in the MP&M category; these sectors

manufacture, maintain and rebuild metal products under more than 200 different SIC codes. EPA

does not intend to include maintenance or repair of metal parts, products, or machines that occur

only as ancillary activities at facilities that it did not include in the 18 industrial sectors. EPA

believes that these ancillary repair and maintenance activities would typically generate only small

quantities of wastewater. As an example, EPA does not intend for the MP&M proposal to include

process wastewater discharges from an on-site machine or maintenance shop at a facility engaged

in the manufacture of organic chemicals when the facility operates that shop to maintain the

equipment related to manufacturing their products (i.e., organic chemicals). Alternatively, since

aircraft is an industrial sector that the Agency considered in developing the MP&M proposal, EPA

is proposing to include process wastewater discharges from activities related to maintaining or

repairing aircraft or other related (metal) equipment (e.g., deicing vehicles) at airports. EPA also

intends to cover wastewater from MP&M operations related to maintenance and repair of metal

products, parts, and machinery at military installations. 

The MP&M industry includes almost 90,000 sites, of which an estimated 63,000

discharge process wastewater. Of the facilities discharging process wastewater, EPA estimates

that 93 percent are indirect dischargers and 7 percent are direct dischargers. The Agency

estimates that there are approximately 26,000 facilities that fall into one of three categories: zero

discharge, non-water-using, or contract haulers.

MP&M sites perform a wide variety of process unit operations on metal parts, products or

machines. In general, MP&M unit operations can be characterized as belonging to one of the

following types of unit operations:

C Assembly/disassembly operations;

C Metal deposition operations;

C Metal shaping operations;

C Organic deposition operations;

C Printed wiring board operations;

C Surface finishing operations;

C Surface preparation operations; and

C Dry dock operations.

At a given MP&M site, the specific unit operations performed, and the sequence of

those operations, depend on many factors, including the activity (i.e., manufacturing, rebuilding, or

maintenance), industrial sector, and type of product processed. The extent to which a facility uses

process water for these unit operations may vary from site to site.

EPA estimates that MP&M sites discharge approximately 120 billion gallons of

process wastewater per year. This wastewater typically contains metal pollutants (e.g., cadmium,

copper, chromium, iron, nickel, zinc) and total suspended solids. MP&M wastewater may also

contain oil and grease, cyanide, hexavalent chromium, and organic pollutants. 
1.0 - Summary and Scope of the Regulation

1-3

EPA identified several in-process pollution prevention, recycling, and end-of-pipe

treatment technologies and practices to control the discharge of pollutants from MP&M facilities. 

Section 8.0 presents a more comprehensive discussion of standard in-process pollution

prevention, recycling, and end-of-pipe treatment technologies and practices and Section 9.0

describes the technology options that EPA analyzed for the proposed rule.

EPA estimated engineering compliance costs for each of the technology options for

a set of statistically selected model sites, and then used these sites to estimate compliance costs for

the entire MP&M industry. The Agency also estimated pollutant loadings and removals associated

with each of the technology options. EPA used the loadings and removals to assess the

effectiveness of each technology option. The Agency used the costs to estimate the financial

impact on the industry of implementing the various options, including the number of potential

facility closures, potential job losses and gains, and the ability of the site to finance the pollution

controls (see “Economic, Environmental, and Benefits Analysis of the Proposed Metal Products &

Machinery Rule” [EPA-821-B-008].) Details on the cost-effectiveness analysis can be found in

the document “Cost-Effectiveness Analysis of the Proposed Effluent Limitations Guidelines and

Standards for the Metal Products & Machinery Point Source Category.” [EPA-821-B-00-007]

1.2 Applicability of MP&M and Overlap with Other Effluent Guidelines

EPA has previously established effluent limitations guidelines and standards for 13 industries that

may perform unit operations or process parts that are sometimes found at MP&M sites. These

effluent guidelines are:

C Electroplating (40 CFR Part 413);

C Iron & Steel Manufacturing (40 CFR Part 420);

C Nonferrous Metals Manufacturing (40 CFR Part 421);

C Ferroalloy Manufacturing (40 CFR Part 424);

C Metal Finishing (40 CFR Part 433);

C Battery Manufacturing (40 CFR Part 461);

C Metal Molding & Casting (40 CFR Part 464);

C Coil Coating (40 CFR Part 465);

C Porcelain Enameling (40 CFR Part 466);

C Aluminum Forming (40 CFR Part 467);

C Copper Forming (40 CFR Part 468);

C Electrical & Electronic Components (40 CFR Part 469); and

C Nonferrous Metals Forming & Metal Powders (40 CFR Part 471).

In 1986, the Agency reviewed coverage of these regulations and identified a

significant number of metals processing facilities discharging wastewater that these 13 regulations

did not cover. Based on this review, EPA performed a more detailed analysis of these unregulated

sites and identified the discharge of significant amounts of pollutants. This analysis resulted in the

decision to develop national limitations and standards for the “Metal Products and Machinery”

(MP&M) point source category. In general, when unit operations and their associated wastewater

discharges are already covered by an existing effluent guideline, they will remain covered under

that effluent guideline. However, EPA is proposing to replace the existing Electroplating (40 CFR
1.0 - Summary and Scope of the Regulation

1-4

413) and Metal Finishing (40 CFR 433) effluent guidelines with the MP&M regulations for all

facilities in the Printed Wiring Board Subcategory and the Metal Finishing Job Shops Subcategory

(see Section 6.0 for a discussion on subcategorization). When a facility covered by existing

metals effluent guidelines (other than Electroplating or Metal Finishing) discharges wastewater

from unit operations not covered under those existing metals guidelines but covered under MP&M,

the facility will need to comply with both regulations. 

EPA has determined that some processes regulated under the 1982 Iron and Steel

Category would be more appropriately regulated under the MP&M Category. The Agency

proposes to include the following steel finishing operations in the MP&M Category: cold forming

and surface finishing (e.g., electroplating) of steel bar, rod, wire, pipe, or tube; hot-dip coating of

steel (except for hot dip coating of steel sheets, strips, or plates); and drawing and coating of steel

wire. The Agency has determined that these operations are more similar to operations performed

at MP&M facilities than to operations performed at iron and steel manufacturing facilities. This

proposed regulation is not covering any hot forming operations or cold forming and surface

finishing operations on steel sheets, strips or plates. Such operations on steel sheets, strips, or

plates will remain regulated under the Iron and Steel Point Source Category (40CFR 420). If a

facility discharges wastewater from operations covered under both the Iron and Steel guideline

and the MP&M guideline, the facility will need to comply with both regulations.

Table 1-1 below summarizes the coverage of industrial operations by each MP&M

subcategory.

Table 1-1

Clarification of Coverage by MP&M Subcategory

Subcategory

Proposing to continue to

cover under 40 CFR

Part 413

(Electroplating)

Proposing to continue to

cover under 40 CFR

Part 433 

(Metal Finishing)

Proposing to cover

under 40 CFR Part 438

(Metal Products &

Machinery)

General Metals Existing facilities that are

currently covered by 413

AND are indirect

dischargers that introduce

less than or equal to 1

million gallons per year

into a POTW.

Existing facilities that are

currently covered (or new

facilities that would be

covered) by 433 AND are

indirect dischargers that

introduce less than or equal

to 1 million gallons per

year into a POTW.

All new and existing direct

dischargers in this

subcategory regardless of

annual wastewater

discharge volume and all

new and existing indirect

dischargers in this

subcategory with annual

wastewater discharges

greater that 1 million

gallons per year. (See

438.10)
Table 1-1 (Continued)

1.0 - Summary and Scope of the Regulation

Subcategory

Proposing to continue to

cover under 40 CFR

Part 413

(Electroplating)

Proposing to continue to

cover under 40 CFR

Part 433 

(Metal Finishing)

Proposing to cover

under 40 CFR Part 438

(Metal Products &

Machinery)

1-5

Metal Finishing

Job Shops

None (see non-chromium

anodizing)

None (see non-chromium

anodizing)

All new and existing direct

and indirect discharges

under this subcategory. 

These facilities would no

longer be covered by 413

or 433. (See 438.20)

Non-Chromium

Anodizers

Note: Facilities

that perform

anodizing with

chromium or with

the use of

dichromate

sealants (or

commingle their

non-chromium

anodizing process

wastewater with

wastewater from

other MP&M

subcategories)

will be covered by

40CFR 438.

Existing indirect

dischargers that are

currently covered by 413

AND that only perform

non-chromium anodizing

(or do not commingle their

non-chromium anodizing

wastewater with other

process wastewater for

discharge).

New and existing indirect

dischargers (not covered by

413) that only perform

non-chromium anodizing

(or do not commingle their

non-chromium anodizing

wastewater with other

process wastewater for

discharge).

Existing and new direct

dischargers that only

perform non-chromium

anodizing (or do not

commingle their nonchromium anodizing

wastewater with other

process wastewater for

discharge). (See 438.30)

Printed Wiring

Board

(Printed Circuit

Board)

None None All new and existing direct

and indirect discharges

under this subcategory. 

These facilities would no

longer be covered by 413

or 433. (See 438.40)

Steel Forming &

Finishing

N/A N/A All new and existing direct

and indirect discharges

under this subcategory as

described. (See 438.50)
Table 1-1 (Continued)

1.0 - Summary and Scope of the Regulation

Subcategory

Proposing to continue to

cover under 40 CFR

Part 413

(Electroplating)

Proposing to continue to

cover under 40 CFR

Part 433 

(Metal Finishing)

Proposing to cover

under 40 CFR Part 438

(Metal Products &

Machinery)

1-6

Oily Wastes N/A N/A All new and existing direct

and indirect dischargers

under this subcategory as

described. (See 438.60). 

(This subcategory excludes

new and existing indirect

dischargers that introduce

less than or equal to 2

MGY into a POTW. 

Facilities under the cutoff

are not and will not be

covered by national

categorical regulations).

Railroad Line

Maintenance

N/A N/A All new and existing direct

dischargers under this

subcategory as described. 

(See 438.70) There are no

national categorical

pretreatment standards for

these facilities.

Shipbuilding Dry

Docks

N/A N/A All new and existing direct

dischargers under this

subcategory as described. 

(See 438.80) There are no

national categorical

pretreatment standards for

these facilities.

N/A: Not applicable.

1.3 Proposed Effluent Limitations Guidelines and Standards

The MP&M effluent guidelines apply to process wastewater discharges from

existing or new industrial sites engaged in manufacturing, rebuilding, or maintenance of metal

parts, products or machines to be used in one of the industrial sectors listed in Section 1.1. The

effluent guidelines only cover process wastewater generated at MP&M facilities. EPA is not

covering non-process wastewater which includes sanitary wastewater, non-contact cooling water,

and stormwater. 
1.0 - Summary and Scope of the Regulation

1-7

Typical unit operations at MP&M facilities include any one or more of the

following:

Table 1-2

Typical Unit Operations Performed at MP&M Sites

 

Unit Operation Name

1. Abrasive Blasting

2. Abrasive Jet Machining

3. Acid Treatment with Chromium

4. Acid Treatment without Chromium

5. Alkaline Cleaning for Oil Removal

6. Alkaline Treatment with Cyanide

7. Alkaline Treatment without Cyanide

8. Anodizing with Chromium

9. Anodizing without Chromium

10. Aqueous Degreasing

11. Assembly/Disassembly

12. Barrel Finishing

13. Burnishing

14. Chemical Conversion Coating without

Chromium

15. Chemical Milling

16. Chromate Conversion Coating

17. Corrosion Preventive Coating

18. Electrical Discharge Machining

19. Electrochemical Machining

20. Electroless Plating

21. Electrolytic Cleaning

22. Electroplating with Chromium

23. Electroplating with Cyanide

24. Electroplating without Chromium or

Cyanide

25. Electropolishing

26. Floor Cleaning

27. Grinding

28. Heat Treating

29. Impact Deformation

30. Machining

31. Metal Spraying

32. Painting - Spray or Brush

33. Painting - Immersion

34. Plasma Arc Machining

35. Polishing

36. Pressure Deformation

37. Salt Bath Descaling

38. Soldering/Brazing

39. Solvent Degreasing

40. Stripping (paint)

41. Stripping (metallic coating)

42. Testing

43. Thermal Cutting

44. Washing Finished Products

45. Welding

46. Wet Air Pollution Control

Source: MP&M survey database.

Numerous sub-operations within those listed above are also included. Many of

these operations frequently have associated rinses that remove materials that preceding processes

deposit on the surface of the workpiece and water-discharging air pollution control devices which

become contaminated with process contaminants removed from the air. EPA is including both of

these wastewater flows under the scope of the regulation.

The Agency is also including wastewater discharges from non-contact,

nondestructive testing performed at MP&M facilities. EPA is not covering wastewater generated

from electroplating-type operations during semiconductor wafer manufacturing or wafer

fabrication processes occurring in a “clean room” environment because it believes that these

operations are much different than the other electroplating operations that EPA is covering by these

guidelines and do not contribute significant amounts of pollutants to the wastewater discharge. 
1.0 - Summary and Scope of the Regulation

1-8

EPA is proposing to cover wastewater generated from washing vehicles only when it occurs as a

preparatory step prior to performing an MP&M unit operation (e.g., prior to disassembly to

perform engine maintenance or rebuilding). EPA is also proposing to cover wastewater generated

from unit operations performed by drum reconditioners/refurbishers to prepare drums for reuse. 

EPA did not collect information with respect to MP&M operations at gasoline service stations,

passenger car rental facilities, or utility trailer and recreational vehicle rental facilities; therefore,

this proposed regulation does not cover process wastewater generated by maintenance and repair

activities when they occur at gasoline stations or car rental facilities. 

 

EPA is proposing to exclude facilities in the General Metals and Oily Wastes

Subcategories that discharge MP&M process wastewater below a specified flow rate (one and

two million gallons per year, respectively). The Agency expects that many facilities that only

perform repair and maintenance activities (e.g., auto repair shops, light aircraft maintenance) will

be excluded as most will fit into the applicability of the either the General Metals or Oily Waste

Subcategories and have process wastewater discharges below the subcategory-specific flow

cutoffs. EPA is considering a higher flow cutoff (three million gallons per year) for the Oily

Wastes Subcategory for the final regulation, and it solicits comment on appropriate flow cutoff

levels for all subcategories in the preamble.

EPA is proposing to cover MP&M process wastewater at mixed-use facilities (i.e.,

any municipal, private, U.S. military or federal facility which contains both industrial and

commercial/administrative buildings at which one or more industrial sites conduct MP&M

operations within the facility’s boundaries). The Agency is not proposing to cover wastewater

from non-metal repair, maintenance or manufacturing operations at mixed use facilities such as

wastewater from residential housing, schools, churches, recreational parks, shopping centers, gas

stations, utility plants, and hospitals. Therefore, EPA is proposing to allow wastewater generated

at different sites within a mixed use facility to be considered as separate discharges for the

purpose of applying the appropriate low flow cutoff (when applicable). 

EPA may divide a point source category (e.g., MP&M) into groupings called

“subcategories” to provide a method for addressing variations between products, raw materials,

processes, and other factors which result in distinctly different effluent characteristics. Regulation

of a category by using formal subcategories provides that each subcategory has a uniform set of

effluent limitations which take into account technological achievability and economic impacts

unique to that subcategory. One result of grouping similar facilities into subcategories is the

increased likelihood that the regulations are practicable, and it diminishes the need to address

variations between facilities through a variance process. The CWA requires EPA, in developing

effluent limitations guidelines and pretreatment standards, to consider a number of different

subcategorization factors. (See Section 6.0 for a list of the factors considered for the proposed

MP&M rule and a detailed discussion of subcategorization).

As a result of the subcategorization analysis, EPA identified 8 distinct

subcategories: General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Oily

Wastes, Printed Wiring Boards, Railroad Line Maintenance, Shipbuilding Dry Docks, and Steel

Forming and Finishing.
1.0 - Summary and Scope of the Regulation

1-9

In the 1995 proposal, EPA proposed concentration-based limits for a portion of the

MP&M Point Source Category with the requirement that control authorities (e.g., POTWs)

implement them as mass-based limits. The Agency did not finalize that proposal and, instead, has

proposed this regulation covering the entire MP&M Point Source Category. EPA proposed

requiring this conversion to mass-based limits because the Agency believed that it was necessary

to ensure the use of water conservation and pollution prevention practices similar to those that

were part of EPA’s selected option (60 FR 28230). EPA received comments on the

administrative burden on POTWs associated with implementation of mass-based limits, largely

due to the fact that most MP&M facilities do not collect production information on a

wastestream-by-wastestream basis. EPA is again proposing concentration-based limits (for all

but one subcategory--Steel Forming & Finishing); however, the Agency is no longer requiring

control authorities (e.g., POTWs) or permit writers to implement the limits on a mass basis. 

Instead EPA authorizes control authorities and permit writers to decide when it is most

appropriate to implement mass-based limits. EPA believes that this approach will reduce

implementation burden on POTWs and will result in increased use of water conservation practices

at the facilities where POTWs and permit writers think it is most needed. 

The proposed limitations are presented in Section 14.0 for each subcategory, and

Section 15.0 provides guidance to permit writers on the conversion of concentration-based limits

to mass-based limits.
2.0 - Background

2-1

2.0 BACKGROUND

This section presents background information supporting the development of

effluent limitations guidelines and standards for the Metal Products and Machinery (MP&M) Point

Source Category. Section 2.1 presents the legal authority to regulate the MP&M industry. Section

2.2 discusses the Clean Water Act, Pollution Prevention Act, Regulatory Flexibility Act (as

amended by the Small Business Regulatory Enforcement Fairness Act of 1996), and prior

regulation of the MP&M industry.

2.1 Legal Authority

EPA is proposing this regulation under the authorities of Sections 301, 304, 306,

307, 308, 402 and 501 of the Clean Water Act, 33 U.S.C. Sections 1311, 1314, 1316, 1317,

1318, 1342 and 1361 and under authority of the Pollution Prevention Act of 1990 (PPA), 42

U.S.C. 13101 et seq., Pub L. 101-508, November 5, 1990.

2.2 Regulatory Background

2.2.1 Clean Water Act

Congress adopted the Clean Water Act (CWA) to "restore and maintain the

chemical, physical, and biological integrity of the nation's waters" (Section 101(a), 33

U.S.C.1251(a)). EPA accomplishes this goal in part by restricting the types and amounts of

pollutants discharged from various industrial, commercial, and public sources of wastewater. 

Direct dischargers must comply with effluent limitations in National Pollutant Discharge

Elimination System ("NPDES") permits; indirect dischargers must comply with pretreatment

standards for pollutants which may pass through or interfere with POTW operations. EPA

establishes these limitations and standards by regulation for categories of industrial dischargers

and bases them on the degree of control that can be achieved using various levels of pollution

control technology. These guidelines and standards are summarized briefly below. 

1. Best Practicable Control Technology Currently Available (BPT)

(Section 304(b)(1) of the CWA).

BPT effluent limitations guidelines are applicable to direct dischargers

(i.e., sites that discharge wastewater to surface water). BPT effluent

limitations guidelines are generally based on the average of the best existing

performance by facilities of various sizes, ages, unit processes or other

common characteristics within the category or subcategory for control of

conventional, priority, and non-conventional pollutants.

In establishing BPT effluent limitations guidelines, EPA first considers the

total cost of achieving effluent pollutant reductions in relation to the effluent

pollutant reduction benefits. The agency also considers the age of

equipment and facilities involved, the processes employed, process
2.0 - Background

2-2

changes required, engineering aspects of the control technologies, nonwater quality environmental impacts (including energy requirements), and

other factors as the Agency deems appropriate. The Agency considers the

category- or subcategory-wide cost of applying the technology in relation to

the effluent pollutant reduction benefits. Where existing performance is

uniformly inadequate, EPA may require higher levels of control than

currently in place in an industrial category if the Agency determines that the

technology can be practically applied.

2. Best Available Technology Economically Achievable (BAT) 

(Sections 304(b)(2)(B) of the CWA).

BAT effluent limitations guidelines are applicable to direct discharging

sites. In general, BAT effluent limitations guidelines represent the best

existing economically achievable performance of plants in the industrial

subcategory or category. The CWA establishes BAT as the principal

national means of controlling the direct discharge of priority pollutants and

nonconventional pollutants to waters of the United States. The factors

considered in assessing BAT include the cost of achieving BAT effluent

reductions, the age of equipment and facilities involved, the processes

employed, engineering aspects of the control technology, potential process

changes, non-water quality environmental impacts (including energy

requirements), and such factors as the Administrator deems appropriate. 

The Agency retains considerable discretion in assigning the weight to be

accorded to these factors. An additional statutory factor considered in

setting BAT is economic achievability. Generally, EPA determines the

economic achievability on the basis of the total cost to the industrial

subcategory and the overall effect of the rule on the industry’s financial

health. As with BPT, where existing performance is uniformly inadequate,

EPA may base BAT upon technology transferred from a different

subcategory within an industry or from another industrial category. In

addition, BAT may include process changes or internal controls, even when

these technologies are not common industry practice. 

3. Best Conventional Pollutant Control Technology (BCT) 

(Section 304(b)(4) of the CWA).

The 1977 Act included Section 301(b)(2)(E), which established BCT for

discharges of conventional pollutants from existing industrial point sources. 

BCT effluent limitations guidelines are applicable to direct discharging

sites. Section 304(a)(4) designated the following as conventional

pollutants: biochemical oxygen demand (BOD5), total suspended solids

(TSS), fecal coliform, pH, and any additional pollutants defined by the

Administrator as conventional. The Administrator designated oil and

grease as an additional conventional pollutant on July 30, 1979 (44 FR

44501).
2.0 - Background

2-3

BCT is not an additional limitation, but replaces BAT for the control of

conventional pollutants. In addition to other factors specified in Section

304(b)(4)(B), the CWA requires that EPA establish BCT limitations after

consideration of a two- part "cost-reasonableness" test. EPA explained its

methodology for the development of BCT limitations in 1986 (51 FR

24974, July 9, 1986).

4. New Source Performance Standards (NSPS) 

(Section 306 of the CWA).

NSPS are applicable to new direct discharging sites and are based on the

best available demonstrated treatment technology. New facilities have the

opportunity to install the best and most efficient production processes and

wastewater treatment technologies. As a result, NSPS should represent the

greatest degree of effluent reduction attainable through the application of the

best available demonstrated control technology for all pollutants (i.e.,

conventional, nonconventional, and priority pollutants). In establishing

NSPS, the CWA directs EPA to take into consideration the cost of

achieving the effluent pollutant reduction and any non-water quality

environmental impacts (including energy requirements).

5. Pretreatment Standards for Existing Sources (PSES) 

(Section 307(b) of the CWA).

PSES are applicable to indirect discharging sites (i.e., sites that discharge

to a publicly owned treatment works (POTW)). The CWA requires PSES

for pollutants that pass through, interfere with, or are otherwise

incompatible with POTW treatment processes or sludge disposal methods. 

The CWA specifies that pretreatment standards are to be technology-based

and analogous to the BAT effluent limitations guidelines.

The General Pretreatment Regulations, which set forth the framework for

implementing categorical pretreatment standards, are found at 40 CFR Part

403. Those regulations contain a definition of pass-through that addresses

local rather than national instances of pass-through and establish

pretreatment standards that apply to all non-domestic dischargers (52 FR

1586, January 14, 1987).

6. Pretreatment Standards for New Sources (PSNS)

(Section 307(b) of the CWA).

PSNS are applicable to new indirect discharging sites. Like PSES, PSNS

are designed to prevent the discharges of pollutants that pass through,

interfere with, or are otherwise incompatible with the operation of POTWs. 

PSNS are to be issued at the same time as NSPS. New indirect dischargers

have the opportunity to incorporate into their plants the best available
2.0 - Background

2-4

demonstrated technologies. The Agency considers the same factors in

promulgating PSNS that it considers in promulgating NSPS.

The following table summarizes these regulatory levels of control and the pollutants controlled.

Table 2-1

Summary of Regulatory Levels of Control

Type of Sites Regulated BPT BAT BCT NSPS PSES PSNS

Existing Direct Dischargers X X X

New Direct Dischargers X

Existing Indirect Dischargers X

New Indirect Dischargers X

Pollutants Regulated BPT BAT BCT NSPS PSES PSNS

Priority Toxic Pollutants X X X X X

Nonconventional Pollutants X X X X X

Conventional Pollutants X X X

Source: Clean Water Act.

2.2.2 Section 304(m) Requirements

Section 304(m) of the Clean Water Act (33 U.S.C. 1314(m)), added by the Water

Quality Act of 1987, requires EPA to establish schedules for (1) reviewing and revising existing

effluent limitations guidelines and standards (“effluent guidelines”), and (2) promulgating new

effluent guidelines. On January 2, 1990, EPA published an Effluent Guidelines Plan (55 FR 80),

in which it established schedules for developing new and revised effluent guidelines for several

industrial categories. In this notice, the Agency identified the Metal Products and Machinery

(formerly referred to as Machinery Manufacturing and Rebuilding) Point Source Category as

requiring effluent guidelines, and identified an estimated schedule for regulatory action.

The Natural Resources Defense Council, Inc. (NRDC) and Public Citizen, Inc.

challenged the Effluent Guidelines Plan in a suit filed in U.S. District Court for the District of

Columbia (NRDC et al. v. Reilly, Civ. No. 89-2980). The plaintiffs charged that EPA’s plan did

not meet the requirements of Section 304(m). A Consent Decree in this litigation was entered by

the Court on January 31, 1992. The terms of the Consent Decree are reflected in the Effluent

Guidelines Plan published on September 8, 1992 (57 FR 41000). As a result of this decree, EPA

established a plan to propose effluent guidelines for the MP&M Point Source Category. As

discussed further in Section 2.2.5, EPA initially divided the industry into two phases based on

industrial sector. The 1992 Effluent Guidelines Plan scheduled EPA to propose the MP&M Phase

I Category by November 1994, and take final action by May 1996. EPA filed a motion with the
2.0 - Background

2-5

court on September 28, 1994, and the court granted an extension for proposal and promulgation of

the final regulation.

On May 30, 1995, EPA published the MP&M Phase I proposal (60 FR 28210). 

EPA received a large number of public comments on the Phase I proposal requesting that the

Agency combine all MP&M industrial sectors into one effluent guideline (see Section 2.2.5). 

Based on these comments and after negotiations with NRDC, EPA filed an unopposed motion in

the U.S. District Court for the District of Columbia to modify the Consent Decree to merge the two

phases of the MP&M effluent guideline and to modify the dates for proposal and final action (61

FR 35042; July 3,1996). The court approved the motion, and the modified dates for the combined

MP&M regulation are October 2000 for proposal and December 2002 for final action (62 FR

8726; February 26,1997).

2.2.3 Pollution Prevention Act

The Pollution Prevention Act of 1990 (42 U.S.C. 13101 et seq., Pub.L. 101-508,

November 5, 1990), makes pollution prevention the national policy of the United States. This act

identifies an environmental management hierarchy in which pollution “should be prevented or

reduced whenever feasible; pollution that cannot be prevented or recycled should be reused in an

environmentally safe manner whenever feasible; pollution that cannot be prevented or recycled

should be treated in an environmentally safe manner whenever feasible; and disposal or release

into the environment should be employed only as a last resort...” (Sec. 6602; 42 U.S.C. 13103). 

According to the Pollution Prevention Act, source reduction reduces the generation

and release of hazardous substances, pollutants, wastes, contaminants, or residuals at the source,

usually within a process. The term source reduction “includes equipment or technology

modifications, process or procedure modifications, reformulation or redesign of products,

substitution of raw materials, and improvements in housekeeping, maintenance, training, or

inventory control. The term source reduction does not include any practice which alters the

physical, chemical, or biological characteristics or the volume of a hazardous substance, pollutant,

or contaminant through a process or activity which itself is not integral to or necessary for the

production of a product or the providing of a service.” In effect, source reduction means reducing

the amount of a pollutant that enters a waste stream or that is otherwise released into the

environment prior to out-of-process recycling, treatment, or disposal. The Pollution Prevention

Act directs the Agency to, among other things, “review regulations of the Agency prior and

subsequent to their proposal to determine their effect on source reduction” (Sec. 6604; 42 U.S.C.

13103). 

2.2.4 Regulatory Flexibility Act (RFA) as Amended by the Small Business 

Regulatory Enforcement Fairness Act of 1996 (SBREFA)

Under the Regulatory Flexibility Act (RFA) [5 U.S. C. 601 et seq., as amended by

the Small Business Regulatory Enforcement Fairness Act (SBREFA)], EPA generally is required

to conduct a regulatory flexibility analysis describing the impact of a proposed rule on small

entities as part of the rulemaking. EPA conducted an initial regulatory flexibility analysis (IRFA)

that examines the impact of the proposed rule on small entities, along with regulatory alternatives
2.0 - Background

2-6

that could reduce that impact. The IRFA is available for review in the MP&M Administrative

Record (as chapter 10 in the Economic, Environmental and Benefits Analysis). Under section

605(b) of the RFA, if EPA certifies that a rule will not have a significant economic impact on a

substantial number of small entities, EPA is not required to prepare a regulatory flexibility

analysis. A regulatory flexibility analysis addresses:

C The need for, objectives of, and legal basis for a rule.

C A description of, and where feasible, an estimate of the number of small

entities to which a rule would apply.

C The projected reporting, recordkeeping, and other compliance requirements

of a rule, including an estimate of the classes of small entities that would be

subject to a rule and the types of professional skills necessary for

preparation of the report or record.

C An identification, where practicable, of all relevant federal rules that may

duplicate, overlap, or conflict with a rule.

C A description of any significant regulatory alternatives to a rule that

accomplish the stated objectives of applicable statutes and that minimize

any significant economic impact of a rule on small entities. Consistent with

the stated objectives of the CWA, the analysis discusses significant

alternatives such as:

– Establishing differing compliance or reporting requirements or

timetables that take into account the resources available to small

entities.

– Clarifying, consolidating, or simplifying of compliance and

reporting requirements under the rule for such small entities.

– Using performance rather than design standards.

– Excluding from coverage of a rule, or any part thereof, such small

entities. Based on the regulatory flexibility analysis and other

factors, EPA considered an exclusion to eliminate disproportionate

impacts on small businesses, which reduced the number of small

businesses that would be affected by a rule.

Pursuant to the RFA as amended by SBREFA, EPA also conducted outreach to

small entities and convened a Small Business Advocacy Review Panel to obtain advice and

recommendations of representatives of the small entities that potentially would be subject to the

rule’s requirements. The Panel comprised representatives from three federal agencies: EPA, the

Small Business Administration, and the Office of Management and Budget. The Panel reviewed

materials EPA prepared in connection with the IRFA, and collected the advice and
2.0 - Background

2-7

recommendations of small entity representatives. For this proposed rule, the small entity

representatives included nine small MP&M facility owner/operators, one small municipality, and

the following six trade associations representing different sectors of the industry: National

Association of Metal Finishers (NAMF)/Association of Electroplaters and Surface Finishers

(AESF)/MP&M Coalition; the Association Connecting Electronics Industries (also known as IPC);

Porcelain Enamel Institute; American Association of Shortline Railroads (ASLRA); Electronics

Industry Association (EIA); and the American Wire Producers Association (AWPA). The Panel

provided background information and analysis to the small entity representatives and conducted

meetings with the representatives. The Panel asked the small entity representatives to submit

written comment on the MP&M rulemaking in relation to the elements of the IRFA. The Panel

carefully considered these comments when developing their recommendations. The Panel

prepared a report (available in the MP&M Administrative Record) that summarizes their outreach

to small entities and the comments submitted by the small entity representatives. The Panel’s

report also presented their findings on issues related to the elements of an IRFA and

recommendations regarding the rulemaking.

2.2.5 Regulatory History of the Metals Industry

EPA has promulgated effluent limitations guidelines and standards for 13 metals

industries. These regulations cover metal manufacturing, metal forming, and component finishing,

as summarized below.

Table 2-2

Summary of Metals Industry Effluent Guidelines

Coverage Area Title CFR Reference

Metal and Metal Alloy

Manufacturing

Iron and Steel Manufacturinga

Nonferrous Metals Manufacturing

Ferroalloy Manufacturing

40 CFR 420

40 CFR 421

40 CFR 424

Metal Forming Iron and Steel Manufacturinga

Metal Molding and Casting

Aluminum Forming

Copper Forming

Nonferrous Metals Forming and Metal Powders

40 CFR 420

40 CFR 464

40 CFR 467

40 CFR 468

40 CFR 471

Component Finishing Electroplating

Iron and Steel Manufacturinga

Metal Finishing

Battery Manufacturing

Coil Coating

Porcelain Enameling

Electrical and Electronic Component Manufacturing

40 CFR 413

40 CFR 420

40 CFR 433

40 CFR 461

40 CFR 465

40 CFR 466

40 CFR 469

Source: Code of Federal Regulations, Part 40.

aThe Iron and Steel Manufacturing category includes metal manufacturing, metal forming, and component

finishing.
2.0 - Background

2-8

In 1986, the Agency reviewed coverage of these 13 regulations and identified a

significant number of metals processing facilities discharging wastewater that these regulations did

not cover. Based on this review, EPA performed a detailed analysis of these unregulated sites and

identified the discharge of significant amounts of pollutants. This analysis resulted in the

formation of the Machinery Manufacturing and Rebuilding (MM&R) Point Source Category. In

1989, the Agency published a Preliminary Data Summary (PDS) for the MM&R industry, which is

located in the MP&M Public Record. Based on information contained in the PDS, EPA divided

the MM&R category into two phases by major industrial groups or sectors. The Agency

announced its schedule for the development of effluent guidelines for two separate MM&R phases

in EPA’s January 2, 1990 Effluent Guidelines Plan (55 FR 80). One of the primary reasons for

dividing the category into two phases was the large number of facilities (over 900,000) identified

in the PDS as potentially included in the MM&R Point Source Category. On May 7, 1992, EPA

changed the category name to Metal Products and Machinery (MP&M) to clarify the coverage of

the category (57 FR 19748). Many questionnaire respondents found the MM&R label confusing

and interpreted the category to apply only to machinery sites. The Agency believes that the

MP&M title more accurately describes the coverage of the category.

The MP&M Point Source Category includes sites that generate wastewater while

processing metal parts, metal products, and machinery. The category covers process wastewater

generated during manufacturing, assembly, rebuilding, repair, or maintenance of metal parts,

products or machines for use in the following industrial sectors:

C Aerospace;

C Aircraft;

C Bus and Truck;

C Electronic Equipment;

C Hardware;

C Household Equipment;

C Instruments;

Job Shops;

C Mobile Industrial Equipment;

C Motor Vehicles;

C Office Machines;

C Ordnance;

C Precious Metals and Jewelry;

C Printed Wiring Boards;

C Railroad;

C Ships and Boats;

C Stationary Industrial Equipment; and

C Miscellaneous Metal Products.

EPA proposed effluent limitations guidelines, pretreatment standards, and new

source performance standards for the seven MP&M Phase I industrial sectors on May 30, 1995

(60 FR 28210). These seven industrial sectors included aerospace, aircraft, electronic equipment,

hardware, mobile industrial equipment, ordnance, and stationary industrial equipment. EPA
2.0 - Background

2-9

received over 4,000 pages of public comment on the Phase I proposal. One area where

commenters from all stakeholder groups (i.e, industry, environmental groups, regulators) were in

agreement was that EPA should not divide the industry into two separate regulations. Commenters

raised concerns regarding the regulation of similar facilities with different compliance schedules

and potentially different limitations solely based on whether they were in a Phase I or Phase II

MP&M industrial sector. Furthermore, many facilities performed work in multiple sectors. In

such cases, permit writers and control authorities (e.g., POTWs) would need to decide which

MP&M rule (Phase I or II) applied to a facility. 

Based on these comments, EPA proposed merging the two phases into one rule (61

FR 35042; July 3, 1996). In 1997, EPA obtained approval from the U.S. District Court for the

District of Columbia to combine MP&M Phases I and II into a single regulation for the 18 MP&M

industrial sectors and to extend the effluent guidelines schedule (62 FR 8726; February 26, 1997). 

Extension of the schedule allowed EPA to use POTW survey data to develop more precise

estimates of administrative burden and allowed more extensive stakeholder involvement for data

collection. Under the 304(m) decree as amended, the final action on the MP&M rule is to be taken

by December 2002.
3.0 - Data Collection Activities

3-1

3.0 DATA COLLECTION ACTIVITIES

This section summarizes the Agency’s data collection activities for the MP&M

rulemaking effort. Section 3.1 summarizes the 1989 and 1996 MP&M industry questionnaires

including their purpose, recipient selection process, types of information collected, and uses of

data, Sections 3.2 and 3.3 summarize the site visit and field sampling programs, respectively,

conducted at MP&M sites. Sections 3.4, 3.5, and 3.6 discuss other data sources.

3.1 Industry Questionnaires

EPA distributed two screener and six detailed questionnaires (surveys) as part of

the data collection effort for the MP&M Point Source Category. As discussed in Section 2.0, EPA

initially divided the MP&M Point Source Category into two phases by major industrial sectors. 

The surveys distributed for the seven Phase I industrial sectors requested data reflecting 1989

operations, and the surveys distributed for the 11 Phase II industrial sectors requested data

reflecting 1996 operations. The table below lists the industry surveys and the distribution dates. 

Sections 3.1.1 and 3.1.2 discuss these questionnaire efforts.

Distribution of the MP&M Industry Surveys

Type of Survey Survey Name Distribution Date

Screener 1989 Screener Survey

1996 Screener Survey

1996 Benefits Screener

8/90

12/96

10/98

Detailed 1989 Detailed Survey

1996 Long Survey

1996 Short Survey

1996 Municipality Survey

1996 POTW Survey

1996 Federal Survey

1/91

6/97

9/97

6/97

11/97

4/98

3.1.1 The 1989 Industry Surveys

EPA distributed a screener and a detailed survey for the initial MP&M proposed

regulation to manufacturing, rebuilding, and/or maintenance facilities engaged in the following

seven industrial sectors: 

C Aerospace;

C Aircraft;

C Electronic Equipment;

C Hardware;

C Mobile Industrial Equipment;
3.0 - Data Collection Activities

3-2

C Ordnance; and

C Stationary Industrial Equipment.

The survey instructions and appendices provide descriptions of the industrial

sectors. The 1989 screener and detailed surveys are discussed below. EPA fully describes the

recipient selection, stratification schemes, and the type and potential use of the information

requested in the Information Collection Request (ICR) for the 1989 screener and detailed metal

products and machinery industry surveys. The ICR can be found in the MP&M Administrative

Record.

3.1.1.1 1989 Screener Survey

In August and September 1990, EPA mailed 8,342 screener surveys [also referred

to as the Mini Data Collection Portfolio (MDCP)] to sites believed to be engaged in MP&M

manufacturing, rebuilding, or maintenance activities in one of the seven industrial sectors listed

above. Mailout of the screener was the preliminary step in an extensive data-gathering effort for

these seven MP&M sectors. The purpose of the screener was to identify sites to receive the more

detailed survey and to make a preliminary assessment of these seven MP&M sectors. 

1989 Screener Recipient Selection and Distribution

The Agency sent the screener to randomly selected MP&M sites engaged in

manufacturing, rebuilding, or maintenance operations in the seven industrial sectors. EPA

identified potential recipients using Standard Industrial Classification (SIC) codes. To examine

trends and similarities in manufacturing across the MP&M industrial sectors, EPA also sent

screener surveys to some facilities performing manufacturing in the following eight industrial

sectors:

C Bus and Truck;

C Household Equipment;

C Instruments;

C Motor Vehicles;

C Office Machines;

C Precious and Nonprecious Metals;

C Railroad; and

C Ships and Boats.

The Agency did not send the screener to sites whose SIC codes indicated that they were engaged in

only MP&M rebuilding or maintenance (not manufacturing) operations in the eight industrial

sectors.

The Agency identified more than 190 SIC codes applicable to the seven MP&M

sectors listed in Section 3.1.1. Within each sector, EPA identified between one and 40 SIC codes. 

EPA calculated the number of sites to receive the screener within each SIC code by a coefficient

of variation (CV) minimization procedure, described in the Statistical Summary for the Metal
3.0 - Data Collection Activities

3-3

Products & Machinery Industry Surveys. Based on the number of sites selected within each SIC

code, the Agency purchased a list of randomly selected names and addresses from the Dun &

Bradstreet database for each SIC code. This list included twice the number of sites specified by

the CV minimization procedure for each SIC code. 

EPA deleted sites from the Dun & Bradstreet list for the following reasons: sites

had SIC codes that were inconsistent with company names; sites were corporate headquarters

without manufacturing, rebuilding, or maintenance operations; or sites had insufficient mailing

addresses. EPA then randomly selected 30 to 60 sites within each SIC code and assigned each

site a randomly selected identification number. EPA assigned each site identification number a

corresponding barcode to track the distribution and processing of the screeners. 

EPA established a toll-free helpline from August through October of 1990 to assist

screener recipients in completing the survey. This helpline received approximately 900 calls from

screener recipients. Additional information about the screener mailing (e.g., a copy of the

screener, specific mailing and processing procedures, non-CBI screener responses, follow-up

letters, and notes from helpline telephone conversations) is discussed in the following sections and

is contained in the MP&M Public Record.

1989 Screener Mailout Results

EPA initially mailed 8,000 screener surveys in August 1990. Based on the number

of surveys returned undelivered, EPA mailed an additional 342 in September 1990. In addition,

EPA received 22 unsolicited responses to the survey. Of the 8,364 potential respondents to the

screener, including those who provided unsolicited responses, 7,846 received the screener. 

Screeners for the remaining 518 were returned to EPA as undeliverable. EPA assumed these sites

to be out of business. Of the total potential respondents, 84 percent (6,981) returned the screener

to EPA. A blank copy of the screener form and nonconfidential portions of the completed

screeners are contained in the MP&M Public Record. Table 3-1 and Figure 3-1 summarize the

mailout results for the 1989 and 1996 survey efforts. 

Information Collected

The Agency requested the following site-specific information in the 1989 screener:

C Name and address of facility;

C Contact person;

C Parent company;

C Sectors in which the site manufactures, rebuilds, or maintains machines or

metal components;
3.0 - Data Collection Activities

3-4

Table 3-1

1989 and 1996 MP&M Survey Mailout Results

Survey Type Mailed

Returned

Undelivered

Returned

(%)

Not

Returned

(%)

Respondents Engaged

in MP&M Operations

(%)

Respondents Not

Engaged in MP&M

Operations

(%)

1989 Screener Survey 8,342 518 6,981a (84) 865 (11) 3,598 (52) 3,373 (48)

1989 Detailed Survey 1,020 0 998b (98) 22 (X) 792 (79) 199 (20)

1996 Screener Survey 5,325 579 4248 (80) 497 (10) 2,424 (57) 1,824 (12)

1996 Benefits Screener 1750 155 1392 (80) 161 (10) 1354 (97) 38(3)

1996 Long Detailed Survey 353 1 311 (88) 41 (12) 297 c (95) 8 (3)

1996 Short Detailed Survey 101 1 83 (82) 17 (17) 75 (90) 8 (10)

1996 Municipality Detailed Survey 150 3 135 (90) 12 (8) 71 (53) 64 (47)

1996 POTW Detailed Survey 150 2 147 (98) 1 (1) 144 (98) 3 (2)

1996 Federal Detailed Survey -- -- 51 (--) -- 44 (86) 7 (14)

a

Includes 22 unsolicited responses.

bSeven of the 1989 detailed surveys were returned too late to be incorporated into the detailed survey database.

c

Includes long survey respondents that discharge <1 mgy.

-- Not applicable to the survey.

Source: 1989 and 1996 Survey Tracking Systems.
3.0 - Data Collection Activities

3-5

52%

84%

79% 98%

57%

80%

97%

80%

95%

88%

90%

82%

53%

90%

98%

98%

86%

NA

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Percentage

1989 Screener 

1989 Detailed

1996 Screener

1996 Benefits Screener

1996 Long Detailed

1996 Short Detailed

1996 Municipality Detailed

1996 POTW Detailed

1996 Federal Detailed

Survey Type

Surveys Returned

Respondents Engaged in MP&M 

Operations

* NA - The number of federal surveys distributed is not certain, and the percentage of returned surveys cannot be calculated.

Figure 3-1. Percentage of 1989 and 1996 MP&M Surveys Returned and 

Percentage of Survey Respondents Engaged in MP&M Unit Operations
3.0 - Data Collection Activities

3-6

C SIC codes corresponding to products at the site;

C Number of employees;

C Annual revenues;

C Unit operations performed at the site;

C Whether there is process water use and/or wastewater discharge for each

unit operation performed at the site; and

C Base metal(s) on which each unit operation is performed.

The Agency used a computerized database system to store and analyze data received from the

screeners. The database dictionary and all nonconfidential screener surveys are located in the

MP&M Public Record. 

EPA determined the number of sites engaged in MP&M operations by responses to

the screener. As shown in Table 3-1, approximately 52 percent of the 1989 screener survey

respondents reported that their sites were engaged in MP&M operations and approximately 48

percent reported no MP&M operations at their sites. The status of 10 of the sites could not be

determined because they returned incomplete screeners and did not respond to follow-up efforts. 

The Agency contacted a statistically representative sample of the nonrespondent

sites (i.e., sites that did not return the screener) and sites reporting “not engaged” in MP&M

operations to determine whether their responses were due to confusion over the scope of the

MP&M industry. Based on the results of this follow-up, EPA adjusted the survey weights for

misclassification and response. The methodology for calculating the adjustment factors is

provided in Chapter 4 of the Statistical Summary for the Metal Products and Machinery Industry

Surveys, Part I which is located in the MP&M Administrative Record.

1989 Screener Data Entry, Engineering Coding, and Analysis

EPA reviewed all of the screener surveys prior to data entry. As part of this effort,

the Agency reviewed all documentation provided by the site, corrected errors and deficiencies,

and coded the information for data entry. In some cases, these revisions required telephone

contact with site personnel. The Agency contacted more than 1,100 screener recipients to resolve

survey deficiencies and code information for data entry. Following preliminary review, EPA

entered the scannable data (i.e., responses to multiple-choice, Mark SenseTM questions) into the

database using a ScantronTM reader. EPA scanned each form twice and compared the information

using a computer program as a quality control (QC) check. The Agency performed double-key

entry of nonscannable data, resolved any inconsistencies, and converted the data to database files.

Based on the screener mailout results, EPA developed an MP&M industry profile

for the seven sectors. The screener database report provides estimates of the national population

for sites in these MP&M sectors with regard to water use characteristics, size, location, sector,
3.0 - Data Collection Activities

3-7

unit operations, and metal types. The Statistical Summary for the Metal Products & Machinery

Industry Surveys discusses the sample size determination and statistical procedures for developing

national estimates for the industry.

3.1.1.2 1989 Detailed Survey

Based on responses to the 1989 screener, EPA sent a more detailed survey to a

select group of water-using MP&M sites. This survey, also referred to as the data collection

portfolio (DCP), was designed to collect detailed 1989 technical and financial information. EPA

used this information to characterize MP&M sites from the seven industrial sectors, develop

pollutant loadings and reductions, and develop compliance cost estimates, as discussed later in

this document. 

EPA mailed 896 detailed surveys in January 1991. Based on the number of

detailed surveys returned undelivered, EPA mailed an additional 124 detailed surveys in January

and February 1991, for a total of 1,020 detailed surveys mailed. A blank copy of the 1989

detailed survey and copies of the nonconfidential portions of the completed detailed surveys are

located in the MP&M Public Record.

1989 Detailed Survey Recipient Selection and Distribution

EPA selected 1,020 detailed survey recipients from the following three groups of

sites: 

C Water-discharging 1989 screener respondents (860 sites);

C Water-using 1989 screener respondents that did not discharge process

water (74 sites); and

C Water-discharging sites from key MP&M companies that did not receive the

1989 screener (86 sites).

The methods used to select sites within each group are described below.

The Agency mailed the 1989 detailed survey to all 860 water-discharging screener

respondents. EPA’s intent in collecting detailed data from all 860 sites was to characterize the

potential variations in unit operations performed and water use practices among water-discharging

sites in these seven MP&M industrial sectors.

The Agency mailed the 1989 detailed survey to a probability sample of 50 screener

respondents that reported using but not discharging process water. EPA selected these sites to

provide information on water-use practices at sites that use but do not discharge process water,

and to determine if “zero-discharge” practices used at those sites could be used at other MP&M

sites. In addition to the 50 probability sample sites, EPA also mailed the 1989 detailed survey to

an additional 24 screener respondents that reported using but not discharging process water. The
3.0 - Data Collection Activities

3-8

Agency selected these sites because they performed unit operations that were not expected to be

sufficiently characterized by detailed surveys mailed to other sites. The unit operations that EPA

expected at each of the 24 sites are listed in the MP&M Public Record. 

EPA mailed the 1989 detailed survey to 86 sites that did not receive the 1989

screener. The Agency identified these sites to represent key companies in the MP&M industry that

EPA did not select as 1989 detailed survey recipients based on the screener mailout. EPA

identified key companies from Dun & Bradstreet company lists, the Thomas Register, Fortune

Magazine’s list of the top 500 U.S. companies, and MP&M site visits at companies with annual

revenues of $50 million or more that EPA believed to be leading companies in their particular

MP&M sector. The Agency contacted each of the key companies to identify sites within the

company that were engaged in MP&M operations and used process water to perform MP&M

operations. Records of these follow-up telephone calls are located in the MP&M Public Record. 

EPA did not use these 86 surveys for developing the national estimates because the Agency did not

randomly select these facilities. 

EPA operated a toll-free telephone helpline from January until July 1991 to assist

recipients in completing the 1989 detailed survey. The helpline received approximately 1,400

calls from detailed survey recipients. Callers to the 1989 detailed survey helpline typically

requested the following: 

C Assistance with the technical sections of the detailed survey (e.g., technical

clarification of unit operation definitions);

C Additional time to complete the survey;

C Assistance with the financial sections of the detailed survey (these calls

were referred to a separate economics helpline); or

C Clarification of the applicability of the survey (i.e., did the survey apply to

the site?). 

Records for nonconfidential telephone calls to the helpline and to EPA personnel are located in the

MP&M Public Record.

1989 Detailed Survey Mailout Results

Table 3-1, on page 3-4, summarizes the results of the detailed survey mailout. Of

the 1,020 sites that received the detailed survey, 998 responded to the survey and 22 did not. Of

the sites that responded, EPA did not include 199 sites in the detailed survey database for one of

the following reasons:

C The site was out of business;

C The site did not use process water;
3.0 - Data Collection Activities

3-9

C The site was not engaged in MP&M operations; or

C Process information at the site was Department of Defense or Department of

Energy classified information. 

Specific reasons for not using data from these sites are located in the MP&M Public Record.

Upon review of the detailed surveys submitted by these sites, EPA determined 87

sites to be in the other 11 industrial sectors rather than the seven sectors identified in Section

3.1.1. Because the scope of the detailed survey mailout effort included only sites from the seven

industrial sectors listed in Section 3.1.1, EPA did not include these 87 sites in the detailed survey

database. 

Information Collected

This section describes the information collected in each part of the 1989 detailed

survey and the reasons for collecting this information. The detailed survey instructions and the

Information Collection Request (ICR) for this project contain further details on the types of and

potential uses for information collected. These documents are located in the MP&M

Administrative Record.

The Agency designed the 1989 detailed survey to collect information necessary to

develop effluent guidelines and standards for the MP&M industry. EPA divided the detailed

survey into the following parts:

C Part I - General Information;

C Part II - Process Information;

C Part III - Water Supply;

C Part IV - Wastewater Treatment and Discharge;

C Part V - Process and Hazardous Wastes; and

C Part VI - Financial and Economic Information. 

Part I (questions 1 through 13) requested information necessary to identify the site,

to characterize the site by certain variables, and to confirm that the site was engaged in MP&M

operations. This information included: site name, address, contact person, number of employees,

facility age, average energy usage, discharge permit status, and MP&M activity (manufacturing,

rebuilding, or maintenance). 

Part II (questions 14 through 21) requested detailed information on MP&M

products, production levels, unit operations, activity, water use for unit operations, wastewater

discharge from unit operations, miscellaneous wastewater sources, waste minimization practices

(e.g., pollution prevention), and air pollution control for unit operations. EPA requested the site to

provide detailed technical information (e.g., water balance, chemical additives, metal type

processed, disposition of wastewater) for each MP&M unit operation and air pollution control
3.0 - Data Collection Activities

3-10

device using process water. This section also requested information on unique and/or auxiliary

MP&M operations. EPA used this information to evaluate raw waste characteristics, water use

and discharge practices, and sources of pollutants for each MP&M unit operation. 

Part III (question 22) requested information on the water supply for the site. EPA

requested the site to specify the source water origin, average intake flow, average intake operating

hours, and the percentage of water used for MP&M operations. EPA used this information to

evaluate overall water use for the site. 

Part IV (questions 23 through 33) requested detailed information on MP&M

influent and effluent wastewater treatment streams and wastewater treatment operations. The

information requested included: the origin of each stream contributing to the site’s overall

wastewater discharge; a block diagram of the wastewater treatment system; detailed technical

information (e.g., wastewater stream flow rates, treatment chemical additives, system capacity,

disposition of treatment sludge) for each wastewater treatment operation; self-monitoring data; and

capital and operating cost data. EPA collected this information to evaluate treatment in place at

MP&M sites, to develop and design a cost model and to assess the long-term variability of MP&M

effluent streams.

Part V (question 34) requested detailed information on the types, amounts, and

composition of wastewater and solid/hazardous wastes generated during production or waste

treatment, and the costs of solid waste disposal. EPA collected this information to evaluate the

types and amounts of wastes currently discharged, the amount of waste that is contract hauled off

site, and the cost of contract-hauling wastes. 

Part VI requested detailed financial and economic information from the site and the

company owning the site. The Economic, Environmental, and Benefits Analysis document for the

proposed rule, which is located in the MP&M Administrative Record, presents information from

this part.

1989 Detailed Survey Review, Coding, and Data Entry

The Agency completed a detailed engineering review of the detailed surveys,

including coding responses to questions from Parts I through V of the detailed surveys to facilitate

entry of technical data into a database. The MP&M DCP Database Dictionary identifies all

database codes developed for this effort and the database dictionary for Section VI of the detailed

survey are located in the MP&M Administrative Record.

The Agency followed up with telephone calls to all respondents who: (1) did not

provide information on operations (manufacturing, rebuilding, or maintenance) or sectors; (2) did

not provide metal type or unit operation descriptions for each water-using unit operation; or (3)

did not provide descriptions for each wastewater treatment operation. EPA also made follow-up

calls to clarify incomplete or contradictory technical or economic information. EPA confirmed all

information obtained from follow-up calls by sending a letter to the site. 
3.0 - Data Collection Activities

3-11

EPA developed a database to store all technical data provided in the detailed

surveys. After engineering review and coding, the Agency entered data from the detailed surveys

into the database using a double key-entry and verification procedure. EPA coded and entered

data from 792 detailed survey respondents determined to be engaged in MP&M activities into the

detailed survey database. The MP&M DCP Database Dictionary presents the database structure

and defines each field in the detailed survey database and the codes that describe data in these

fields. 

1989 Detailed Survey Data Analysis

The Statistical Summary for the Metal Products & Machinery Industry Surveys

provides estimates of the national population of MP&M water-discharging sites with regard to

size, location, sector, unit operations, metal types, discharge flows, and production-normalized

flows. The report discusses the statistical procedures for developing national estimates for the

industry, and is located in the MP&M Administrative Record.

3.1.2 The 1996 Industry Surveys

Between 1996 and 1998, EPA distributed one screener and five detailed surveys. 

The five detailed surveys included the long, short, municipality, federal, and publicly owned

treatment works (POTW) surveys. The Agency distributed the 1996 surveys to commercial and

government (federal, state, and local) facilities that manufacture, rebuild, or maintain metal

products or parts to be used in one of the following 11 MP&M industrial sectors:

C Bus and Truck;

C Household Equipment;

C Instruments;

C Job Shops;

C Motor Vehicles;

C Office Machines;

C Precious Metals and Jewelry;

C Printed Wire Boards;

C Railroad;

C Ships and Boats; and

C Miscellaneous Metal Products.

The job shop sector includes facilities that manufacture, rebuild, or maintain metal products or

parts but do not own 50 percent or more of the items they process. EPA distributed the POTW

detailed survey to POTWs to assess the impact of the MP&M regulation on permitting entities. The

1996 screener and detailed surveys are discussed below. Recipient selection, stratification

schemes, and the type and potential use of the information requested are described in more detail

in the ICR for the 1996 screener and detailed metal products machinery industry surveys which is

located in the MP&M Administrative Record.
3.0 - Data Collection Activities

3-12

3.1.2.1 1996 Screener Surveys

In December 1996 and February 1997, EPA distributed 5,325 screener surveys to

sites believed to be engaged in MP&M manufacturing, rebuilding, or maintenance activities in one

of 11 MP&M industrial sectors listed above. The purpose of the screener surveys was to identify

sites to receive the more detailed survey and to make a preliminary assessment of the MP&M

industry for the 11 industrial sectors listed in Section 3.1.2. EPA sent an additional 1,750

screeners to facilities located in Ohio (a state with a high concentration of MP&M facilities) as

part of the benefits study. The Agency used these screeners to collect data to analyze

environmental benefits.

1996 Screener Recipient Selection and Distribution

As discussed above, EPA sent the 1996 screener survey to 5,325 randomly

selected MP&M sites (includes replacement sites). The Agency selected potential recipients from

the Dun & Bradstreet database based on the industrial sector (using the SIC code), activity (i.e.,

manufacturing, maintenance, or rebuilding), size as measured by number of employees, and

wastewater discharge flow rate.

The Agency identified more than 126 SIC codes applicable to the 11 MP&M

sectors. Within each sector, EPA identified between 1 and 26 SIC codes. EPA calculated the

number of sites to receive the 1996 screener within each SIC code by a coefficient of variation

(CV) minimization procedure described in the Statistical Summary for the Metal Products &

Machinery Industry Surveys. Based on the number of sites selected within each SIC code, the

Agency obtained a list of randomly selected names and addresses from Dun & Bradstreet. This

list included twice the number of sites specified by the CV minimization procedure for each SIC

code. EPA randomly selected the initial list of sites from the Dun & Bradstreet database for each

SIC code. 

EPA reviewed the potential sites and deleted sites for the following reasons:

C The site was a corporate headquarters without manufacturing, rebuilding, or

maintenance operations;

C The site received a 1989 screener or detailed survey;

C The site was a duplicate of a miscellaneous facility in the list of potential

MP&M sites.

C The site had an SIC code which was inconsistent with company name; or

C The site had an insufficient mailing address.

EPA established a toll-free telephone helpline and an electronic mail address to

assist screener recipients in completing the survey. EPA received helpline calls and electronic
3.0 - Data Collection Activities

3-13

mail inquiries from more than 600 screener recipients. Nonconfidential notes from helpline and

review follow-up calls are located in the MP&M Public Record.

1996 Screener Mailout Results

EPA initially mailed 4,900 surveys in December 1996. The Agency distributed an

additional 425 surveys to replace surveys that were returned undelivered. EPA assumed the

undeliverable sites to be out of business. Of the 5,325 surveys mailed, 80 percent (4,248) of the

recipients returned completed surveys to EPA. A blank copy of the 1996 screener and

nonconfidential portions of the completed screeners are located in the MP&M Public Record. 

Table 3-1 and Figure 3-1, on pages 3-4 and 3-5, summarize the MP&M survey mailout results.

The Agency contacted a statistically representative sample of nonrespondent sites

to determine whether these sites were engaged in MP&M operations and discharged process

wastewater. Only 24 percent of the nonrespondents contacted were engaged in MP&M operations,

and approximately half of these facilities did not discharge process wastewater. 

Information Collected

The Agency requested the following site-specific information in the screener:

C Name and address of facility;

C Contact person;

C Whether process water is used at the site;

C Destination of process wastewater discharged;

C Volume of process wastewater discharged;

C Number of employees;

C Annual revenue;

C Sectors in which the site manufactures, rebuilds, or maintains machines or

metal components; and

C Unit operations performed at the site and whether there is water use and/or

wastewater discharge for each unit operation performed at the site.

The Agency used a computerized database system to store and analyze data

received from the 1996 screeners. Nonconfidential portions of the screener surveys and the

database dictionary are located in the MP&M Administrative Record.
3.0 - Data Collection Activities

3-14

1996 Screener Data Review and Data Entry

EPA reviewed the 1996 screener survey for accuracy and consistency and

formatted the information for data entry. The Agency contacted approximately 1,800 screener

respondents to resolve deficient and inconsistent information prior to data entry. Following

review, EPA double key-entered and compared the data from the formatted screeners, using a

computer program, as a quality control check. The Agency then reviewed the database files for

deficiencies and inconsistencies, and resolved all issues for the final survey database.

1996 Benefits Screener Survey

For an environmental benefits study, EPA sent the 1996 screener survey to 1,750

(including replacement sites) randomly selected sites in Ohio, a state with a large number of

MP&M sites. EPA used the data for the environmental benefit analyses. The selection criteria

and sampling frame for the benefits screener recipients are described in more detail in memoranda

located in the MP&M Administrative Record.

The Agency initially mailed the benefits screener to 1,600 facilities in October

1998. EPA mailed an additional 150 facilities the screener in February 1999 to replace surveys

that were returned undelivered. The Agency assumed the undeliverable surveys to be out of

business. Of the 1,750 surveys mailed, 80 percent (1,392) of the recipients returned completed

screeners to EPA. A blank copy of the 1996 benefits screener and nonconfidential portions of the

completed benefits screeners are located in the MP&M Public Record. Table 3-1 and Figure 3-1,

on pages 3-4 and 3-5, summarize MP&M mailout results.

EPA established a toll-free telephone helpline and an electronic mail address to

assist screener recipients in completing the survey. EPA received helpline calls and electronic

mail inquiries from more than 900 benefits screener recipients. Nonconfidential notes from

helpline and review follow-up calls are located in the MP&M Public Record.

The Agency followed the same review, data entry, and database development

procedures used for the original 1996 screener survey. The benefits screener database is

discussed in the Economic, Environmental, and Benefits Analysis of the Proposed Metal Products

& Machinery Rule. EPA contacted more than 400 screener respondents to resolve deficient and

inconsistent information prior to data entry.

3.1.2.2 1996 Long Detailed Survey

EPA distributed the long detailed surveys in June 1997 to 353 MP&M wastewaterdischarging industrial facilities. EPA designed this survey to gather detailed technical and

economic information required to develop the MP&M effluent limitations guidelines and

standards. The long survey is discussed below.
3.0 - Data Collection Activities

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1996 Long Survey Recipient Selection and Distribution

In June 1997, EPA sent the long survey to all 353 1996 screener respondents who

indicated they performed operations in one of the 11 MP&M industrial sectors listed in Section

3.1.2 and discharged one million or more gallons of MP&M process wastewater annually. EPA

established a toll-free telephone helpline and an electronic mail address to assist long survey

recipients in completing the survey. EPA received helpline calls and electronic mail inquiries

from approximately 200 long survey recipients. Nonconfidential notes from helpline and review

follow-up calls are located in the MP&M Public Record.

1996 Long Survey Mailout Results

Of the 353 surveys mailed, 88 percent (311) of the recipients returned completed

surveys to EPA. One survey was returned as undelivered and EPA assumed the facility to be out

of business. A blank copy of the 1996 long survey and nonconfidential portions of the completed

long surveys are located in the MP&M Public Record. Table 3-1 and Figure 3-1, on pages 3-4

and 3-5, summarize the MP&M survey mailout results.

Information Collected

This section describes the information collected in each section of the 1996 long

survey and the reason EPA collected the information. Further details on the types of information

collected and the potential uses of the information are contained in the ICR for this project and in

the survey instructions which are located in the MP&M Administrative Record. 

EPA divided the long detailed survey into the following sections:

C Section I: General Site Information;

C Section II: General Process Information;

C Section III: Specific Process Information;

C Section IV: Economic Information; and

C Section V: Voluntary Supplemental Information.

Table 3-2 summarizes the information requested in the 1996 long, short, federal, and municipality

detailed surveys by question number. EPA designed the long, short, municipality, and federal

surveys to collect similar detailed process information from different audiences, as discussed

below for each survey.
3.0 - Data Collection Activities

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Table 3-2

Summary of 1996 Detailed Survey Information by Question Number

Survey Question Number

Type of Information Requested

Long and

Federal Short Municipality

Section I

1

Section I

1

Part II

1 Industrial sector activities

Section II

2-5

Section II

2-5 2-5 Site location and facility contact

6,7 6, 7 5, 6 Number of employees and age of site

8,9 8, 9 7, 8 Discharge status and destination

10 10 9 Permits under Miscellaneous categorical effluent guidelines

--- 11-12 10-11 Types of end-of-pipe wastewater treatment units

11 13 12 Metal types processed

12 15 13 5 major products (quantity and sector)

13 16 14 Unit operations: water use and associated rinses

Section III

14-15 --- --- General water use and costs

16 --- --- Production process diagram

17-23 --- --- Detailed description of wet unit operations performed

24-29

Section II

17 16 In-process pollution prevention technologies or practices

30 --- --- Wastewater treatment (WWT) diagram

31-41 --- --- Detailed design and operating parameters of WWT units

42 --- --- WWT costs by treatment unit

43-44

Section II

14 15 Wastewater sampling and analysis conducted

45 --- --- Contract haul and disposal costs

--- --- --- Facility comments page

Section IV

1-9

Section IV

1-8

Part I

1-3 Financial and economic data

Section V

1

Section V

1 --- Parent firm name and contact, number of Miscellaneous MP&M

facilities

2 2 --- Number of employees for Miscellaneous facility(ies)

3 3 --- MP&M sector and activity 

2, 4 2, 4 --- Discharge status and destination

5 5 --- Unit operations: water use and discharge status

--- Question is not applicable to this survey.
3.0 - Data Collection Activities

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Section I requested information to determine if the facility was engaged in MP&M

operations. Question 1 requested the site to identify the MP&M industrial sector and type of

activity (manufacturing, rebuilding, or maintenance) performed.

Section II requested information to identify the site location and contact person,

number of employees, facility age, process wastewater discharge status and destination, and 

wastewater discharge permits and permitting authority. This section also requested general 

information about metal types processed, MP&M products and production levels, water use for

unit operations, and wastewater discharge from unit operations. EPA used the process information

to evaluate water use and discharge practices, and sources of pollutants for each MP&M unit

operation.

Section III requested detailed information on MP&M wet unit operations, pollution

prevention practices, wastewater treatment technologies, costs for water use and wastewater

treatment systems, and wastewater/sludge disposal costs. EPA also requested the site to provide

block diagrams of the production process and the wastewater treatment system. The unit operation

information requested included: metal types processed, production rate, operating schedule,

chemical additives, volume and destination of process wastewater and rinse waters, in-process

pollution prevention technologies, and in-process flow control technologies. The information

requested for each wastewater treatment unit included: operating flow rate, design capacity,

operating time, chemical additives, and unit operations discharging to each treatment unit. In

addition, EPA requested the site to provide the type of MP&M wastewater sampling data

collected. EPA used these data to characterize the industry, to perform subcategorization analyses,

to identify best management practices, to evaluate performance of the treatment technology for

inclusion in the regulatory options, and to develop regulatory compliance cost estimates. 

Section IV requested detailed financial and economic information about the site or

the company owning the site. Information from this section is presented in the Economic,

Environmental, and Benefits Analysis of the Proposed Metal Products & Machinery Rule, which is

located in the MP&M Administrative Record.

Section V requested supplemental information on Miscellaneous MP&M facilities

owned by the company. EPA included this voluntary section to measure the combined impact of

proposed MP&M effluent guidelines on companies with multiple MP&M facilities that discharge

process wastewater. This section requested the same information collected in the 1996 MP&M

screener survey. Responses to questions in this section provided the size, industrial sector,

revenue, unit operations, and water usage of the company’s Miscellaneous MP&M facilities. 

1996 Long Survey Data Review and Data Entry

EPA completed a detailed engineering review of Sections I through III of the

detailed survey to evaluate the accuracy of technical information provided by the respondents. 

During the engineering review, EPA coded responses to facilitate entry of technical data into the

long survey database. The MP&M 1996 Long Survey Database Dictionary identifies the database

codes developed for this project, and is located in the MP&M Administrative Record. EPA
3.0 - Data Collection Activities

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contacted approximately 240 long survey respondents, by telephone and letter, to clarify

incomplete or inconsistent technical information prior to data entry.

The Agency developed a database for the technical information provided by survey

respondents. After engineering review and coding, EPA entered data from 297 long surveys into

the database using a double key-entry and verification procedure. The MP&M 1996 Long Survey

Database Dictionary presents the database structure and defines each field in the files for the long

survey database. EPA did not include data from 14 long survey respondents in the database for the

following reasons:

C The site was out of business;

C The site did not use process water;

C The site was not engaged in MP&M operations; or

C The site provided insufficient data and the survey was returned too late to

enter into the database.

3.1.2.3 1996 Short Detailed Survey

EPA distributed the short surveys in September 1997 to 101 MP&M wastewaterdischarging industrial facilities. EPA designed this survey to gather technical and economic

information required to develop the MP&M effluent limitations guidelines and standards. The

short survey is discussed below.

1996 Short Survey Recipient Selection and Distribution

EPA initially sent 100 short surveys in September 1997 and mailed one additional

survey to a site to replace a short survey that was returned undelivered; EPA assumed the

undeliverable site to be out of business. The Agency sent the short surveys to randomly selected

1996 screener respondents who performed operations in one of the 11 MP&M industrial sectors

identified in Section 3.1.2 and indicated they discharged less than one million gallons of MP&M

process wastewater annually. The selection criteria and sampling frame for short survey

recipients are described in more detail in the Statistical Summary for the Metal Products &

Machinery Industry Surveys.

EPA established a toll-free telephone helpline and an electronic mail address to

assist short survey recipients in completing the survey. EPA received helpline calls and electronic

mail inquiries from approximately 20 short survey recipients. Nonconfidential notes from helpline

and review follow-up calls are located in the MP&M Public Record.
3.0 - Data Collection Activities

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1996 Short Survey Mailout Results

Of the 101 surveys mailed, 82 percent (83 surveys) of the recipients returned

completed surveys to EPA. A blank copy of the 1996 short survey and nonconfidential portions of

the completed short surveys are located in the MP&M Public Record. Table 3-1 and Figure 3-1,

on pages 3-4 and 3-5, summarize the MP&M survey mailout results.

Information Collected

The information collected in the 1996 short survey included the identical general

site and process information and economic information collected in Sections I, II, IV, and V of the

long detailed survey (see Section 3.1.2.2). To minimize the burden on facilities discharging less

than one million gallons of process wastewater, EPA did not require these facilities to provide the

detailed information on MP&M unit operations or treatment technologies that EPA requested in

Section III of the long survey. The ICR for this project and the survey instructions have further

details on the types of information collected and the potential uses of the information.

EPA divided the short survey into the following sections:

C Section I: General Site Information;

C Section II: General Process Information;

C Section IV: Economic Information; and

C Section V: Voluntary Supplemental Information.

Table 3-2, on page 3-16, summarizes the 1996 short survey information by question number. 

1996 Short Survey Data Review and Data Entry

EPA completed a detailed engineering review of Sections I and II of the short

survey to evaluate the accuracy of technical information provided by the respondents. During the

engineering review, EPA coded responses to facilitate entry of technical data into the short survey

database. The MP&M 1996 Short Survey Database Dictionary identifies the database codes

developed for this project and is located in the MP&M Administrative Record. EPA contacted

more than 60 short survey respondents, by telephone and letter, to clarify incomplete or

inconsistent technical information prior to data entry.

The Agency developed a database for the technical information provided by survey

respondents. After engineering review and coding, EPA entered data for 75 short surveys into the

database using a double key-entry and verification procedure. The MP&M 1996 Short Survey

Database Dictionary presents the database structure and defines each field in the files for the short

survey database. EPA did not include data from eight short survey respondents in the database for

the following reasons:

C The site was out of business;

C The site did not use process water; or
3.0 - Data Collection Activities

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C The site was not engaged in MP&M operations.

3.1.2.4 1996 Municipality Detailed Survey

EPA distributed the municipality surveys in June 1997 to 150 city and county

facilities that might operate MP&M facilities. EPA designed this survey to measure the impact of

this rule on municipalities and Miscellaneous government entities that perform maintenance and

rebuilding operations on MP&M products (i.e., bus and truck, automobiles, etc.). 

Recipient Selection and Distribution

 The Agency sent the municipality survey to 150 city and county facilities randomly

selected from the Municipality Year Book-1995 based on population and geographic location. 

EPA allocated sixty percent of the sample to municipalities and 40 percent to counties. The 60/40

distribution was approximately proportional to their aggregate populations in the frame. The

Agency divided the municipality sample and the county sample into three size groupings as

measured by population. For municipalities, the population groupings were: less than 10,000

residents, 10,000 - 50,000 residents, and 50,000 or more residents. For counties, the population

groupings were: less than 50,000 residents, 50,000-150,000 residents, and 150,000 or more

residents. The geographic stratification conformed to the Census definitions of Northeast, North

Central, South, Pacific, and Mountain states.

EPA established a toll-free telephone helpline and an electronic mail address to

assist municipality survey recipients in completing the survey. EPA received helpline calls and

electronic mail inquiries from more than 50 municipality survey recipients. Notes from helpline

and review follow-up calls are located in the MP&M Administrative Record.

1996 Municipality Survey Mailout Results

EPA distributed 150 municipality surveys in June 1997. Three surveys were

returned undelivered. Of the 150 surveys mailed, 90 percent (135) of the recipients returned

completed surveys to EPA. A blank copy of the 1996 municipality survey and nonconfidential

portions of the completed municipality surveys are located in the MP&M Public Record. Table 3-

1 and Figure 3-1, on pages 3-4 and 3-5, summarize the MP&M survey mailout results.

Information Collected

The 1996 municipality survey collected economic information for the entire

municipality and site-specific process information for each MP&M site operated by the

municipality. The ICR for this project and the survey instructions contain further details on the

types of information collected and the potential uses of the information and are located in the

MP&M Administrative Record.
3.0 - Data Collection Activities

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EPA divided the municipality detailed survey into the following parts:

C Part I: Economic and Financial Information; and

C Part II: General Site-Specific Process Information.

Table 3-2, on page 3-16, summarizes the 1996 municipality survey information by question

number. 

Part I requested information to provide the site location and contact person, number

of employees, detailed financial and economic information about the entire municipality, and

information necessary to determine if the municipality owned and operated MP&M sites in any of

the MP&M industrial sectors. Information from this section is presented in the Economic,

Environmental, and Benefits Analysis of the Proposed Metal Products & Machinery Rule, which is

located in the MP&M Administrative Record.

Part II requested site-specific process information for each MP&M site owned and

operated by the municipality. Question 1 requested the site to identify the MP&M industrial sector

and type of activity (manufacturing, rebuilding, or maintenance) performed. The remaining

questions were identical to Section II of the short detailed survey and requested facility age,

process wastewater discharge status and destination, wastewater discharge permits and permitting

authority, general information about metal types processed, MP&M products and production

levels, water use for unit operations, and wastewater discharge from unit operations. The Agency

used the process information to evaluate water use and discharge practices, and sources of

pollutants for each MP&M unit operation.

1996 Municipality Survey Data Review and Data Entry

EPA completed a detailed engineering review of Part II of the municipality survey

to evaluate the accuracy of technical information provided by the respondents. During the

engineering review, the Agency coded responses to facilitate entry of technical data into the

municipality survey database. The MP&M 1996 Municipality Survey Database Dictionary

identifies the database codes developed for this project, and is located in the MP&M

Administrative Record. EPA contacted more than 50 municipality survey respondents by

telephone to clarify incomplete or inconsistent technical information prior to data entry. 

The Agency developed a database for the technical information provided by survey

respondents. After engineering review and coding, EPA entered data from 209 municipality

facilities into the database using a double key-entry and verification procedure. This number is

greater than the number of respondents because some municipalities had more than one site

engaged in MP&M operations. The MP&M 1996 Municipality Survey Database Dictionary

presents the database structure and defines each field in the files for the municipality survey

database.
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3.1.2.5 1996 Federal Facilities Detailed Survey

In April 1998, EPA distributed the federal facilities detailed survey to the

following seven federal agencies: 

C Department of Energy;

C Department of Defense;

C National Aeronautics and Space Administration (NASA);

C Department of Transportation ( including the United States Coast Guard);

C Department of Interior;

C Department of Agriculture; and

C United States Postal Service.

EPA designed this survey to assess the impact of the MP&M effluent limitations guidelines and

standards on federal agencies that operate MP&M facilities.

Recipient Selection and Distribution

There was no specific sampling frame for the federal survey. EPA distributed the

survey to federal agencies likely to perform industrial operations on metal products or machines. 

EPA requested representatives of seven federal agencies to voluntarily distribute copies of the

survey to sites they believed performed MP&M operations. The selection criteria for federal

survey recipients are described in more detail in the ICR for the 1996 MP&M industry surveys. 

Because the sample was not randomly selected, EPA did not use data from these surveys to

develop national estimates.

EPA established a toll-free telephone helpline and an electronic mail address to

assist federal survey recipients in completing the survey. EPA received helpline calls and

electronic mail inquiries from approximately 20 federal survey recipients. Nonconfidential notes

from helpline and review follow-up calls are located in the MP&M Public Record.

1996 Federal Survey Distribution Results

EPA distributed the federal surveys to seven federal agencies and requested that

they forward copies to any of their sites that performed MP&M operations. The Agency received

51 completed federal surveys. Of the 51 returned surveys, 39 were Department of Defense

facilities and 12 were NASA facilities. A blank copy of the 1996 federal survey and

nonconfidential portions of the completed federal surveys are located in the MP&M Public

Record.

Information Collected

The information collected in the 1996 federal survey was identical to the long

survey. The federal survey included the same five sections and questions discussed in Section

3.1.2.2. The ICR for this project and the survey instructions contain further details on the types of
3.0 - Data Collection Activities

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information collected and the potential uses of the information . Table 3-2, on page 3-22,

summarizes the 1996 federal detailed survey information by question number. 

Data Review and Data Entry

EPA completed a detailed engineering review of Sections I through III of the

federal detailed survey to evaluate the accuracy of technical information provided by the

respondents. During the engineering review, the Agency coded responses to facilitate entry of

technical data into the federal survey database. The MP&M 1996 Federal Survey Database

Dictionary identifies the database codes developed for this project and is located in the MP&M

Administrative Record. 

The Agency developed a database for the technical information provided by survey

respondents. After engineering review and coding, EPA entered data from 44 federal surveys into

the database using a double key-entry and verification procedure. The Agency did not include data

from seven federal survey responses in the database because the sites did not use MP&M process

water. The MP&M 1996 Federal Survey Database Dictionary presents the database structure and

defines each field in the files for the federal survey database.

3.1.2.6 1997 Iron and Steel Industry Short Survey Data

As part of its effort to review and revise effluent limitations guidelines and

standards for the iron and steel industry, EPA distributed the iron and steel industry short survey to

402 iron and steel facilities in November 1998. Following field sampling of iron and steel sites

and review of the completed industry surveys, EPA decided that some iron and steel operations

would be covered more appropriately by the MP&M rule because they were more like MP&M

operations. These operations are steel forming and surface treatment processes and include the

following:

C Acid Cleaning/Pickling;

C Alkaline Cleaning;

C Annealing;

C Conversion Coating (e.g., passivation, surface activation/fluxing)

C Electrolytic Cleaning

C Electroplating

C Cold Forming (e.g., wire, bar, and rod drawing, pipe and tube forming)

C Hot Dip Coating;

C Lube (lime, Borax, etc.)

C Painting

C Salt Bath Descaling

C Shot Blasting; and

C Wet Air Pollution Control. 

The wastewater characteristics and flows for these operations are similar to those seen in the

MP&M industry, and less like the wastewater characteristics and flows associated with
3.0 - Data Collection Activities

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the large, continuous flat-rolled products (e.g., sheet, strip, and plate) and the hot-forming

operations at steel manufacturing facilities. 

Based on EPA’s decision regarding these operations, the Agency transferred 154

iron and steel surveys to the MP&M project. Of the 154 surveys transferred, 47 sites discharge

process wastewater, 64 do not discharge process wastewater, and 43 sites discharge storm water

only. The Agency coded and entered process and wastewater treatment information from 47 iron

and steel surveys into the MP&M costing input database. The sites included in the costing effort

were sites discharging process wastewater. The 107 iron and steel zero discharge and

stormwater-only sites were not included in the costing effort. A blank copy of the 1997 iron and

steel short survey and nonconfidential portions of the 47 completed iron and steel surveys are

located in the MP&M Public Record.

3.1.2.7 1996 Publicly Owned Treatment Works (POTW) Detailed Survey

EPA distributed the POTW survey to 150 sites in November 1997. The Agency

designed this survey to estimate benefits associated with implementation of the MP&M regulations

and to estimate possible costs and burden that POTWs might incur in writing and maintaining

MP&M permits or other control mechanisms. 

Recipient Selection and Distribution

The Agency sent the POTW survey to 150 POTWs with flow rates greater than 0.50

million gallons per day. EPA randomly selected the recipients from the 1992 Needs Survey

Review, Update, and Query System Database. EPA divided the POTW sample into two strata by

daily flow rates: 0.50 to 2.50 million gallons, and 2.50 million gallons or more. The selection

criteria and sampling frame for POTW survey recipients are described in more detail in the ICR

for the 1996 surveys.

EPA established a toll-free telephone helpline and an electronic mail address to

assist POTW survey recipients in completing the survey. EPA received helpline calls and

electronic mail inquiries from approximately 50 POTW survey respondents. Nonconfidential

notes from helpline and review follow-up calls are located in the MP&M Administrative Record.

1996 POTW Survey Mailout Results

EPA distributed 150 POTW surveys in November 1997. Two surveys were

returned undelivered. Of the 150 surveys mailed, 98 percent (147) of the recipients returned

completed surveys to EPA. A blank copy of the 1996 POTW survey and nonconfidential portions

of the completed POTW surveys are located in the MP&M Public Record. Table 3-1 and Figure

3-1, on pages 3-4 and 3-5, summarize the MP&M survey mailout results.
3.0 - Data Collection Activities

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Information Collected

The POTW survey requested data required to estimate benefits associated with

implementation of the MP&M regulations and to estimate possible costs and burden that POTWs

might incur in writing and maintaining MP&M permits or other control mechanisms. The ICR for

this project and the survey instructions contain further details on the types of information collected

and the potential uses of the information. EPA divided the POTW survey into the following parts:

C Part I: Introduction and Basic Information;

C Part II: Administrative Permitting Costs; and

C Part III: Sewage Sludge Use or Disposal Costs.

Part I requested site location and contact information, and the total volume of

wastewater treated at the site. EPA used the wastewater flow information to characterize the size

of the POTW.

Part II requested the number of industrial permits written, the cost to write the

permits, the permitting fee structure, the percentage of industrial dischargers covered by National

Categorical Standards (i.e., effluent guidelines), and the percentage of permits requiring expensive

administrative activities. EPA used this information to estimate administrative burden and costs.

Part III requested information on the use or disposal of sewage sludge generated by

the POTW. EPA required only POTWs that received discharges from an MP&M facility to

complete Part III. The sewage sludge information requested included the amount generated, use or

disposal method, metal levels, use or disposal costs, and the percentage of total metal loadings at

the POTW from MP&M facilities. The Agency used this information to assess the potential

changes in sludge handling resulting from the MP&M rule and to estimate economic benefits to the

POTW related to sludge disposal and reduction in upsets/interference.

Data Review and Data Entry

EPA performed a detailed review of Parts I through III of the POTW detailed

survey to evaluate the accuracy of information provided by the respondents. During review, the

Agency coded responses to facilitate entry of data into the POTW detailed survey database. The

database dictionary for the POTW survey identifies the database codes developed for this project,

and is located in the MP&M Administrative Record. EPA contacted more than 95 POTW survey

respondents by telephone to clarify incomplete or inconsistent information prior to data entry.

The Agency developed a database for the information provided by survey

respondents. After review and coding, EPA entered data from 147 POTW surveys into the

database using a double key-entry and verification procedure. The database dictionary presents

the database structure and defines each field in the files for the POTW survey database.
3.0 - Data Collection Activities

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3.2 Site Visits

The Agency visited 201 MP&M sites between 1986 and 1999 to collect

information about MP&M unit operations, water use practices, pollution prevention and treatment

technologies, and waste disposal methods, and to evaluate sites for potential inclusion in the

MP&M sampling program (described in Section 3.3). In general, the Agency visited sites to

encompass the range of sectors, unit operations, and wastewater treatment technologies within the

MP&M industry (discussed in Section 3.2.1). Table 3-3 lists the number of sites visited within

each MP&M sector. The total number of site visits presented in this table exceeds 201 because

EPA classified some sites in multiple sectors. Figure 3-2 presents the number of MP&M sites

visited and sampled by industrial sector.

Table 3-3 

Number of Sites Visited Within Each MP&M Sector

Industrial Sectors

Total

Number of

Sites Visited Industrial Sectors

Total

Number of

Sites Visited

Aerospace

Aircraft

Bus and Truck

Electronic Equipment

Hardware

Household Equipment

Instrument

Job Shops

Mobile Industrial Equipment

13

32

8

22

15

4

4

20

7

Motor Vehicle

Office Machines

Ordnance

Precious Metals and Jewelry

Printed Wire Boards

Railroad

Ships and Boats

Stationary Industrial Equipment

Miscellaneous Metal Products

20

5

15

2

9

10

7

14

0

Source: MP&M Site Visits.

3.2.1 Criteria for Site Selection

The Agency based site selection on information contained in the MP&M screener

and detailed surveys. The Agency also contacted regional EPA personnel, state environmental

agency personnel, and local pretreatment coordinators to identify MP&M sites believed to be

operating in-process source reduction and recycling technologies and/or well-operated end-ofpipe wastewater treatment technologies.

The Agency used the following four general criteria to select sites that

encompassed the range of sectors and unit operations within the MP&M industry.

1. The site performed MP&M unit operations in one of the industrial sectors. 

To assess the variation of unit operations and water use practices across

sectors, the Agency visited sites in each of the MP&M sectors.
3.0 - Data Collection Activities

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13

2

32 9

8

4

22

4

15 4

4

2

4

2

20

8

NA

7

2

20

9

5

2

15 3

2 (both)

9

3

10

4

7

3

14 4

0 5 10 15 20 25 30 35

Number of Sites

Aerospace

Aircraft

Bus and Truck

Electronic Equipment

Hardware

Household Equipment

Instruments

Job Shop Metal Finishing

Miscellaneous Metal Products

Mobile Industrial Equipment

Motor Vehicles

Office Machines

Ordnance

Precious Metals and Jewelry

Printed Wire Boards

Railroad

Ships and Boats

Stationary Industrial Equipment

Industrial Sector

Number of Sites Sampled

Number of Sites Visited

Figure 3-2. Number of MP&M Sites Visited and Sampled by Industrial Sector
3.0 - Data Collection Activities

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2. The site performed MP&M unit operations that needed to be characterized

for development of the regulation.

3. The site had water use practices that were believed to be representative of

the best sites within an industrial sector.

4. The site operated in-process source reduction, recycling, or end-of-pipe

treatment technologies EPA was evaluating in developing the MP&M

technology options. 

The Agency also attempted to visit sites of various sizes. EPA visited sites with

wastewater flows ranging from less than 200 gpd to more than 1,000,000 gpd.

Site-specific selection criteria are discussed in site visit reports (SVRs) prepared

for each site visited by EPA. The SVRs are located in the MP&M Administrative Record.

3.2.2 Information Collected

During the site visits, EPA collected the following types of information:

C Unit operations performed at the site and the types of metals processed

through these operations;

C Purpose of unit operations performed and purpose for any process water

and chemical additions used by the unit operations;

C Types and disposition of wastewater generated at the site;

C Types of in-process source reduction and recycling technologies performed

at the site;

C Cross-media impacts of in-process source reduction and recycling

technologies;

C Types of end-of-pipe treatment technologies performed at the site; and

C Logistical information required for sampling.

This information is documented in the SVRs for each site. Non-confidential SVRs can be found in

the MP&M Public Record.

3.3 Wastewater and Solid Waste Sampling

The Agency conducted sampling episodes at 72 sites between 1986 and 1999 to

obtain data on the characteristics of MP&M wastewater and solid wastes. In addition, EPA
3.0 - Data Collection Activities

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performed sampling episodes to assess the following: the loading of pollutants to surface waters

and POTWs from MP&M sites; the effectiveness of technologies designed to reduce and remove

pollutants from MP&M wastewater; and the variation of MP&M wastewater characteristics across

unit operations, metal types processed in each unit operation, and sectors. Table 3-4 indicates the

number of sites sampled within each MP&M sector. The number of sampled sites presented in the

table does not equal 72 because EPA conducted multiple sampling episodes at some sites, and

EPA classified some sites in multiple sectors. Figure 3-2 on page 3-27 presents the number of

sites visited and sampled by industrial sector.

Table 3-4

Number of Sites Sampled Within Each MP&M Sector

Industrial Sectors

Total Number

of Sites

Sampled Industrial Sectors

Total Number

of Sites

Sampled

Aerospace

Aircraft

Bus and Truck

Electronic Equipment

Hardware

Household Equipment

Instruments

Job Shops

Mobile Industrial Equipment

2

9

4

4

4

2

2

8

2

Motor Vehicle

Office Machines

Ordnance

Precious Metals and Jewelry

Printed Wiring Boards

Railroad

Ships and Boats

Stationary Industrial Equipment

Miscellaneous Metal Products

9

2

3

2

3

4

3

4

0

Source: MP&M Sampling Episodes.

3.3.1 Criteria for Site Selection

The Agency used information collected during MP&M site visits to identify

candidate sites for sampling. The Agency used the following general criteria to select sites for

sampling:

C The site performed MP&M unit operations EPA was evaluating for

development of the MP&M regulation;

C The site processed metals through MP&M unit operations for which the

metal type/unit operation combination needed to be characterized for the

sampling database;

C The site performed in-process source reduction, recycling, or end-of-pipe

treatment technologies that EPA was evaluating for technology option

development; and
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C The site performed unit operations in a sector that EPA was evaluating for

development of the MP&M regulation.

The Agency also attempted to sample at sites of various sizes. EPA sampled at sites with

wastewater flows ranging from less than 200 gpd to more than 1,000,000 gpd.

After EPA selected a site for sampling, the Agency prepared a detailed sampling

and analysis plan (SAP), based on the information contained in the SVR and follow-up

correspondence with the site. EPA prepared the SAPs to ensure collection of samples that would

be representative of the sampled waste streams. The SAPs contained the following types of

information: site-specific selection criteria for sampling; information about site operations;

sampling point locations and sample collection, preservation, and transportation procedures; site

contacts; and sampling schedules.

3.3.2 Information Collected

In addition to wastewater and solid waste samples, the Agency collected the

following types of information during each sampling episode:

C Dates and times of sample collection;

C Flow data corresponding to each sample;

C Production data corresponding to each sample of wastewater from MP&M

unit operations;

C Design and operating parameters for source reduction, recycling, and

treatment technologies characterized during sampling; 

C Information about site operations that had changed since the site visit or that

were not included in the SVR; and

C Temperature and pH of the sampled waste streams.

EPA documented all data collected during sampling episodes in the sampling

episode report (SER) for each sampled site. Nonconfidential SERs are located in the MP&M

Public Record. Many of the SERs also contain preliminary technical analyses of treatment system

performance (where applicable) as compared to treatment performance data collected for previous

metals industry regulatory development efforts. 

3.3.3 Sample Collection and Analysis

The Agency collected, preserved, and transported all samples according to EPA

protocols as specified in EPA’s Sampling and Analysis Procedures for Screening of Industrial
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Effluents for Priority Pollutants (1) and the MP&M Quality Assurance Project Plan (QAPP). 

These documents are located in the MP&M Administrative Record.

In general, EPA collected composite samples from wastewater streams with

compositions that the Agency expected to vary over the course of a production period (e.g.,

overflowing rinse waters, wastewater from continuous recycling and treatment systems). The

Agency collected grab samples from unit operation baths or rinses that the facility did not

continuously discharge and the Agency did not expect to vary over the course of a production

period. EPA also collected composite samples of wastewater treatment sludge at 11 facilities. 

EPA collected the required types of quality control samples as described in the MP&M QAPP,

such as blanks and duplicate samples, to verify the precision and accuracy of sample analyses. 

The Agency shipped samples via overnight air transportation to EPA-approved

laboratories, where the samples were analyzed for metal and organic pollutants and additional

parameters (including several water quality parameters). EPA analyzed metal pollutants using

EPA Method 1620 (2), volatile organic pollutants using EPA Method 1624 (3), and semivolatile

organic pollutants using EPA Method 1625 (4). Tables 3-5 and 3-6 list the metal and organic

pollutants, respectively, analyzed using these methods. Table 3-5 also lists additional metal

pollutants that EPA analyzed in the MP&M sampling program, but, as specified by EPA Method

1620, were not subject to the rigorous quality assurance/quality control procedures established by

the QAPP. The Agency used these metals analyses for screening purposes and did not select the

metals for regulation in this rulemaking (see Section 7.0). EPA analyzed additional parameters,

including several water quality parameters, using analytical methods contained in EPA’s Methods

for Chemical Analysis of Water and Wastes (5). Table 3-7 lists these parameters, along with the

method and technique used to analyze for each parameter. Method descriptions are included in the

MP&M QAPP. The specific parameters measured in each sample are listed in the SER for each

sampling episode. 

Quality control measures used in performing all analyses complied with the

guidelines specified in the analytical methods and in the MP&M QAPP. EPA reviewed all

analytical data to ensure that these measures were followed and that the resulting data were within

the QAPP-specified acceptance criteria for accuracy and precision.

As discussed previously, upon receipt and review of the analytical data for each

site, EPA prepared an SER to document the data collected during sampling, the analytical results,

and the technical analyses of the results. The SAPs and correspondence with site personnel are

included as appendices to the SERs. 
3.0 - Data Collection Activities

3-32

Table 3-5

Metal Constituents Measured Under the MP&M Sampling Program

(EPA Method 1620)

Metal Constituents

ALUMINUM

ANTIMONY

ARSENIC

BARIUM

BERYLLIUM

BORON

CADMIUM

CALCIUM

CHROMIUM

COBALT

COPPER

IRON

LEAD

MAGNESIUM

MANGANESE

MERCURY

MOLYBDENUM

NICKEL

SELENIUM

SILVER

SODIUM

THALLIUM

TIN

TITANIUM

VANADIUM

YTTRIUM

ZINC

Additional Metal Constituentsa Not Subject to Rigorous QA/QC Procedures Per Method 1620

BISMUTH

CERIUM

DYSPROSIUM

ERBIUM

EUROPIUM

GADOLINIUM

GALLIUM

GERMANIUM

GOLD

HAFNIUM

HOLMIUM

INDIUM

IODINE

IRIDIUM

LANTHANUM

LITHIUM

LUTETIUM

NEODYMIUM

NIOBIUM

OSMIUM

PALLADIUM

PHOSPHORUS

PLATINUM

POTASSIUM

PRASEODYMIUM

RHENIUM

RHODIUM

RUTHENIUM

SAMARIUM

SCANDIUM

SILICON

STRONTIUM

SULFUR

TANTALUM

TELLURIUM

TERBIUM

THORIUM

THULIUM

TUNGSTEN

URANIUM

YTTERBIUM

ZIRCONIUM

aAnalyses for these metals were used for screening purposes, and the metals were not selected for regulation in

this rulemaking.

Source: EPA Method 1620. 
3.0 - Data Collection Activities

3-33

Table 3-6

Organic Constituents Measured Under the MP&M Sampling Program

(EPA Methods 1624 and 1625)

Volatile Organic Constituents (EPA Method 1624)

ACRYLONITRILE

BENZENE

BROMODICHLOROMETHANE

BROMOMETHANE

CARBON DISULFIDE

CHLOROACETONITRILE

CHLOROBENZENE

CHLOROETHANE

CHLOROFORM

CHLOROMETHANE

CIS-1,3-DICHLOROPROPENE

CROTONALDEHYDE

DIBROMOCHLOROMETHANE

DIBROMOMETHANE

DIETHYL ETHER

ETHYL CYANIDE

ETHYL METHACRYLATE

ETHYLBENZENE

IODOMETHANE

ISOBUTYL ALCOHOL

M-XYLENE

METHYL METHACRYLATE

METHYLENE CHLORIDE

O+P-XYLENE

TETRACHLOROETHENE

TETRACHLOROMETHANE

TOLUENE

TRANS-1,2-DICHLOROETHENE

TRANS-1,3-DICHLOROPROPENE

TRANS-1,4-DICHLORO-2-BUTENE

TRIBROMOMETHANE

TRICHLOROETHENE

TRICHLOROFLUOROMETHANE

VINYL ACETATE

VINYL CHLORIDE

1,1-DICHLOROETHANE

1,1-DICHLOROETHENE

1,1,1-TRICHLOROETHANE

1,1,1,2-TETRACHLOROETHANE

1,1,2-TRICHLOROETHANE

1,1,2,2-TETRACHLOROETHANE

1,2-DIBROMOETHANE

1,2-DICHLOROETHANE

1,2-DICHLOROPROPANE

1,2,3-TRICHLOROPROPANE

1,3-BUTADIENE, 2-CHLORO

1,3-DICHLOROPROPANE

1,4-DIOXANE

2-BUTANONE

2-CHLOROETHYL VINYL ETHER

2-HEXANONE

2-PROPANONE

2-PROPEN-1-OL

2-PROPENAL

2-PROPENENITRILE, 2-METHYL3-CHLOROPROPENE

4-METHYL-2-PENTANONE

Semivolatile Organic Constituents (EPA Method 1625)

ACENAPHTHENE

ACENAPHTHYLENE

ACETOPHENONE

ALPHA-TERPINEOL

ANILINE

ANILINE, 2,4,5-TRIMETHYLANTHRACENE

ARAMITE

BENZANTHRONE

BENZENETHIOL

BENZO(A)ANTHRACENE

BENZO(A)PYRENE

BENZO(B)FLUORANTHENE

BENZO(GHI)PERYLENE

BENZO(K)FLUORANTHENE

BENZOIC ACID

BENZONITRILE, 3,5-DIBROMO-4-HYDROXYBENZYL ALCOHOL

BETA-NAPHTHYLAMINE

BIPHENYL
Table 3-6 (Continued)

3.0 - Data Collection Activities

Semivolatile Organic Constituents (EPA Method 1625)

3-34

BENZIDINE

BIS(2-CHLOROETHOXY)METHANE

BIS(2-CHLOROETHYL) ETHER

BIS(2-CHLOROISOPROPYL) ETHER

BIS(2-ETHYLHEXYL) PHTHALATE

BUTYL BENZYL PHTHALATE

CARBAZOLE 

CHRYSENE

CIODRIN

CROTOXYPHOS

DI-N-BUTYL PHTHALATE

DI-N-OCTYL PHTHALATE

DI-N-PROPYLNITROSAMINE

DIBENZO(A,H)ANTHRACENE

DIBENZOFURAN

DIBENZOTHIOPHENE

DIETHYL PHTHALATE

DIMETHYL PHTHALATE

DIMETHYL SULFONE

DIPHENYL ETHER

DIPHENYLAMINE

DIPHENYLDISULFIDE

ETHANE, PENTACHLOROETHYL METHANESULFONATE

ETHYLENETHIOUREA

FLUORANTHENE

FLUORENE

HEXACHLOROBENZENE

HEXACHLOROBUTADIENE

HEXACHLOROCYCLOPENTADIENE

HEXACHLOROETHANE

HEXACHLOROPROPENE

HEXANOIC ACID

INDENO(1,2,3-CD)PYRENE

ISOPHORONE

ISOSAFROLE

LONGIFOLENE

MALACHITE GREEN

MESTRANOL

METHAPYRILENE

METHYL METHANESULFONATE

N-DECANE

N-DOCOSANE

N-DODECANE

STYRENE

THIANAPHTHENE

THIOACETAMIDE

THIOXANTHE-9-ONE

TOLUENE, 2,4-DIAMINOBIPHENYL, 4-NITRO

 N-EICOSANE

N-HEXACOSANE

N-HEXADECANE

N-NITROSODI-N-BUTYLAMINE

N-NITROSODIETHYLAMINE

N-NITROSODIMETHYLAMINE

N-NITROSODIPHENYLAMINE

N-NITROSOMETHYLETHYLAMINE

N-NITROSOMETHYLPHENYLAMINE

N-NITROSOMORPHOLINE

N-NITROSOPIPERIDINE

N-OCTACOSANE

N-OCTADECANE

N-TETRACOSANE

N-TETRADECANE

N-TRIACONTANE

N,N-DIMETHYLFORMAMIDE

NAPHTHALENE

NITROBENZENE

O-ANISIDINE

O-CRESOL

O-TOLUIDINE

O-TOLUIDINE, 5-CHLOROP-CHLOROANILINE

P-CRESOL

P-CYMENE

P-DIMETHYLAMINOAZOBENZENE

P-NITROANILINE

PENTACHLOROBENZENE

PENTACHLOROPHENOL

PENTAMETHYLBENZENE

PERYLENE

PHENACETIN

PHENANTHRENE

PHENOL

PHENOL, 2-METHYL-4,6-DINITROPHENOTHIAZINE

PRONAMIDE

PYRENE

PYRIDINE

RESORCINOL

SAFROLE

SQUALENE

2-NITROANILINE

2-NITROPHENOL

2-PHENYLNAPHTHALENE

2-PICOLINE

2,3-BENZOFLUORENE
Table 3-6 (Continued)

3.0 - Data Collection Activities

Semivolatile Organic Constituents (EPA Method 1625)

3-35

1-BROMO-2-CHLOROBENZENE

1-BROMO-3-CHLOROBENZENE

1-CHLORO-3-NITROBENZENE

1-METHYLFLUORENE

1-METHYLPHENANTHRENE

1-NAPHTHYLAMINE

1-PHENYLNAPHTHALENE

1,2-DIBROMO-3-CHLOROPROPANE

1,2-DICHLOROBENZENE

1,2-DIPHENYLHYDRAZINE

1,2,3-TRICHLOROBENZENE

1,2,3-TRIMETHOXYBENZENE

1,2,4-TRICHLOROBENZENE

1,2,4,5-TETRACHLOROBENZENE

1,2:3,4-DIEPOXYBUTANE

1,3-DICHLORO-2-PROPANOL

1,3-DICHLOROBENZENE

1,3,5-TRITHIANE

1,4-DICHLOROBENZENE

1,4-DINITROBENZENE

1,4-NAPHTHOQUINONE

1,5-NAPHTHALENEDIAMINE

2-(METHYLTHIO)BENZOTHIAZOLE

2-CHLORONAPHTHALENE

2-CHLOROPHENOL

2-ISOPROPYLNAPHTHALENE

2-METHYLBENZOTHIOAZOLE

2-METHYLNAPHTHALENE

2,3,4,6-TETRACHLOROPHENOL

2,3,6-TRICHLOROPHENOL

2,4 -DICHLOROPHENOL

2,4-DIMETHYLPHENOL

2,4-DINITROPHENOL

2,4-DINITROTOLUENE

 2,4,5-TRICHLOROPHENOL

2,4,6-TRICHLOROPHENOL

2,6-DI-TERT-BUTYL-P-BENZOQUINONE

2,6-DICHLORO-4-NITROANILINE

2,6-DICHLOROPHENOL

2,6-DINITROTOLUENE

3-METHYLCHOLANTHRENE

3-NITROANILINE

3,3'-DICHLOROBENZIDINE

3,3'-DIMETHOXYBENZIDINE

3,6-DIMETHYLPHENANTHRENE

4-AMINOBIPHENYL

4-BROMOPHENYL PHENYL ETHER

4-CHLORO-2-NITROANILINE

4-CHLORO-3-METHYLPHENOL

4-CHLOROPHENYL PHENYL ETHER

4-NITROPHENOL

4,4'-METHYLENEBIS(2-CHLOROANILINE)

4,5-METHYLENE PHENANTHRENE

5-NITRO-O-TOLUIDINE

7,12-DIMETHYLBENZ(A)ANTHRACENE

Source: EPA Methods 1624 and 1625.
3.0 - Data Collection Activities

3-36

Table 3-7

Additional Parameters Measured Under the MP&M Sampling Program

Parameter EPA Method

Acidity 305.1

Alkalinity 310.1

Ammonia as Nitrogen 350.1

BOD 5-Day (Carbonaceous) 405.1

Chemical Oxygen Demand (COD) 410.1

410.2

Chloride 325.3

Cyanide, Total 335.2

Cyanide, Amenable 335.1

Fluoride 340.2

Nitrogen, Total Kjeldahl 351.2

Oil and Grease 413.2

Oil and Grease (as HEM) 1664

pH 150.1

Phenolics, Total Recoverable 420.2

Phosphorus, Total 365.4

Sulfate 375.4

Sulfide, Total 376.1, 376.2

Total Dissolved Solids (TDS) 160.1

Total Organic Carbon (TOC) 415.1

Total Petroleum Hydrocarbons (as SGT-HEM) 1664

Total Suspended Solids (TSS) 160.2

Ziram 630.1

Source: EPA Methods for Chemical Analysis of Water and Wastes.
3.0 - Data Collection Activities

3-37

3.4 Other Sampling Data

Extension of the MP&M effluent guidelines schedule, as discussed in Section 2.2,

allowed more stakeholder involvement for data collection. The Association of American

Railroads (AAR), the Hampton Roads Sanitation District (HRSD), and the Los Angeles County

Sanitation Districts (LACSD) proposed potential sampling sites to the Agency, and EPA visited

these sites to identify candidates for sampling. After conducting site visits, EPA selected five sites

for sampling episodes. 

EPA selected the five sites to characterize end-of-pipe treatment technologies in

metal finishing and aircraft parts job shops and the railroad and shipbuilding industrial sectors. 

The site sampled by AAR performs railroad line maintenance and uses dissolved air flotation

(DAF) to treat MP&M process wastewater. The site sampled by HRSD manufactures ships and

boats and uses DAF, chemical precipitation, and cyanide destruction to treat process wastewater. 

The three sites sampled by LACSD were two metal finishing job shops and one aircraft parts

manufacturing job shop. EPA selected the LACSD sites to provide data for cyanide treatment and

also conducted effluent variability sampling at one of the metal finishing job shops.

EPA prepared detailed SAPs based on the information collected during the five

site visits, and AAR, HRSD and LACSD collected the wastewater samples. EPA also prepared

the sampling episode reports. In addition to the wastewater samples, sampling personnel obtained

the collection date and time, sample flow data, treatment unit design and operating parameters, and

temperature and pH of the sampled waste streams. All data collected during sampling episodes

are documented in the SER for each sampled site which are located in the MP&M Administrative

Record. The SERs also contain preliminary technical analyses of treatment system performance

(where applicable) as compared to treatment performance data collected for previous metals

industry regulatory development efforts. EPA combined these data with data collected from the

MP&M sampling program.

EPA collected, preserved, and transported all samples according to EPA protocols

as specified in EPA’s Sampling and Analysis Procedures for Screening of Industrial Effluents for

Priority Pollutants and the MP&M QAPP. Shipping and analysis of the samples were similar to

that discussed in Section 3.3 with the exception that some samples were shipped directly to

internal sanitation district laboratories for analysis. Pollutant parameters and analytical methods

were agreed upon by EPA, AAR, HRSD, and LACSD and were treated as equivalent to the EPA

MP&M sampling program.

3.5 Other Industry-Supplied Data

EPA evaluated other industry data in developing the MP&M effluent guidelines. 

The data sources reviewed included public comments to the 1995 MP&M Phase I proposed rule,

the Metal Finishing F006 Benchmark Study (8), data supporting the Final Rule for the F006

Accumulation Time Extension (65 FR 12377, March 8, 2000), data provided by the Aluminum

Anodizing Council (AAC), the American Wire Producers Association (AWPA), and the

Aerospace Association. EPA also reviewed data from storm water pollution prevention plans
3.0 - Data Collection Activities

3-38

provided by several shipbuilding sites, dry dock data from a shipbuilding site, and data from

periodic compliance monitoring reports/discharge monitoring reports for 14 sites that were part of

the Agency’s wastewater sampling program. Data submitted with the MP&M Phase I comments

did not include the quality control data required to verify the accuracy of sample analyses and,

therefore, EPA did not use the data. 

3.6 Other Data Sources

In developing the MP&M effluent guidelines, EPA evaluated the following existing

data sources:

1. EPA Engineering and Analysis Division (EAD) databases from

development of effluent guidelines for Miscellaneous metals industries;

2. The Office of Research and Development (ORD) National Risk

Management and Research Laboratory (NRMRL) treatability database;

3. The Fate of Priority Pollutants in Publicly Owned Treatment Works (50

POTW Study) database;

4. The Domestic Sewage Study; and

5. The Toxics Release Inventory (TRI) database.

These data sources and their uses for the development of the MP&M effluent guidelines are

discussed below.

3.6.1 EPA/EAD Databases

As discussed in Section 2.0, EPA has promulgated effluent guidelines for 13

metals industries. In developing these past effluent guidelines, EPA collected wastewater samples

to characterize the unit operations and treatment systems at sites in these industries. MP&M sites

operate many of the same or similar sampled unit operations and treatment systems; therefore, EPA

evaluated these data for transfer to the MP&M effluent guidelines development effort.

For the MP&M pollutant loading and wastewater characterization efforts, EPA

reviewed the data collected for unit operations performed at both MP&M sites and at sites in the

other metals industries. EPA reviewed the Technical Development Documents (TDDs), sampling

episode reports, and supporting rulemaking record materials for the other metals industries to

identify available data. EPA used these data for the preliminary assessment of the MP&M

industry, but did not use these data for the MP&M pollutant loadings because EPA obtained

sufficient data from the MP&M sampling program to characterize the MP&M unit operations.

For the MP&M technology effectiveness assessment effort, EPA reviewed

sampling data collected to characterize treatment systems for the development of effluent
3.0 - Data Collection Activities

3-39

guidelines for Miscellaneous metals industries. For several previous effluent guidelines, EPA

used treatment data from metals industries to develop the Combined Metals Database (CMDB),

which served as the basis for developing limits for these industries. EPA also developed a

separate database used as the basis for limits for the Metal Finishing category. EPA used the

CMDB and Metal Finishing data as a guide in identifying well-designed and well-operated

MP&M treatment systems. EPA did not use these data in developing the MP&M technology

effectiveness concentrations, since the Agency collected sufficient data from MP&M sites to

develop technology effectiveness concentrations.

3.6.2 Fate of Priority Pollutants in Publicly Owned Treatment Works Database

In September 1982, EPA published the Fate of Priority Pollutants in Publicly

Owned Treatment Works (6), referred to as the 50 POTW Study. The purpose of this study was to

generate, compile, and report data on the occurrence and fate of the 129 priority pollutants in 50

POTWs. The report presents all of the data collected, the results of preliminary evaluations of

these data, and the results of calculations to determine the following:

C The quantity of priority pollutants in the influent to POTWs;

C The quantity of priority pollutants discharged from the POTWs;

C The quantity of priority pollutants in the effluent from intermediate process

streams; and

C The quantity of priority pollutants in the POTW sludge streams.

EPA used the data from this study as one of the ways to assess removal by POTWs of MP&M

pollutants of concern. To provide consistency for data analysis and establishment of removal

efficiencies, EPA reviewed the 50-POTW Study and standardized the reported minimum levels of

quantitation (MLs) for use in the MP&M proposed rule. EPA’s review of the 50-POTW Study is

described in more detail in Section 7.3.1, in the appendices to Section 7, and in memoranda

located in Section 6.4 of the MP&M Public Record.

3.6.3 National Risk Management Research Laboratory (NRMRL) Treatability

Database

EPA’s Office of Research and Development (ORD) developed the NRMRL

(formerly RREL) treatability database to provide data on the removal and destruction of chemicals

in various types of media, including water, soil, debris, sludge, and sediment. This database

contains treatability data from POTWs as well as industrial facilities for various pollutants. The

database includes physical and chemical data for each pollutant, the types of treatment used to treat

the specific pollutants, the types of wastewater treated, the size of the POTW or industrial plant,

and the treatment concentrations achieved. EPA used the NRMRL database to estimate pollutant

reductions achieved by POTWs for MP&M pollutants of concern that were not found in the 50-

POTW database. The Agency used these prcent removal estimates in calculating the pollutant
3.0 - Data Collection Activities

3-40

loads removed by indirect dishcarging MP&M facilities. Because the 50-POTW database

contained sufficient data, EPA did not use these percent removal estimates in the pass-through

analysis. EPA used only treatment technologies representative of typical POTW secondary

treatment operations (i.e., activated sludge, activated sludge with filtration, aerated lagoons). The

Agency further edited these files to include information pertaining only to domestic or industrial

wastewater. The Agency used these percent removal estimates in calculating the pollutant loads

removed by indirect discharging MP&M facilities. Because the 50-POTW database contained

sufficient data, EPA did not use these percent removal estimates in the pass-through analysis. EPA

used pilot-scale and full-scale data, and eliminated bench-scale data and data from less reliable

references.

3.6.4 The Domestic Sewage Study

In February 1986, EPA issued the Report to Congress on the Discharge of

Hazardous Wastes to Publicly Owned Treatment Works (7), referred to as the Domestic Sewage

Study (DSS). This report, which was based in part on the 50 POTW Study, revealed a significant

number of sites discharging pollutants to POTWs. These pollutants are a threat to the treatment

capability of the POTW. These pollutants were not regulated by national effluent regulations. 

Some of the major sites identified were in the metals industries, particularly one called equipment

manufacturing and assembly. This industry included sites that manufacture such products as office

machines, household appliances, scientific equipment, and industrial machine tools and equipment. 

The DSS estimated that this category discharges 7,715 metric tons per year of priority hazardous

organic pollutants, which are presently unregulated. Data on priority hazardous metals discharges

were unavailable for this category. Further review of the DSS revealed Miscellaneous categories

that were related to metals industries, namely the motor vehicle category, which includes servicing

of new and used cars and engine and parts rebuilding, and the transportation services category,

which includes railroad operations, truck service and repair, and aircraft servicing and repair. 

EPA used the information in the DSS in developing the 1989 Preliminary Data Summary (PDS) for

the MP&M category.

3.6.5 Toxics Release Inventory (TRI) Database

The TRI database contains specific toxic chemical release and transfer information

from manufacturing facilities throughout the United States. This database was established under

the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA), which Congress

passed to promote planning for chemical emergencies and to provide information to the public

about the presence and release of toxic and hazardous chemicals. Each year, manufacturing

facilities meeting certain activity thresholds must report the estimated releases and transfers of

listed toxic chemicals to EPA and to the state or tribal entity in whose jurisdiction the facility is

located. The TRI list includes more than 300 chemicals in 20 chemical categories.

EPA considered using the TRI database in developing the MP&M effluent

guidelines. However, EPA did not use TRI data on wastewater discharges from MP&M sites

because sufficient data were not available for effluent guidelines development. For example, in

developing the MP&M effluent guidelines, EPA uses wastewater influent concentrations to
3.0 - Data Collection Activities

3-41

characterize a facility’s wastewater and to calculate treatment efficiency (i.e., percent removal

across the treatment system). The TRI database does not provide concentrations for the influent to

a facility’s treatment system. EPA also did not use the data on wastewater discharge because

many MP&M sites do not meet the reporting thresholds for the TRI database.

3.7 References

1. U.S. Environmental Protection Agency. Sampling and Analysis Procedures for

Screening of Industrial Effluents for Priority Pollutants, April 1977.

2. U.S. Environmental Protection Agency. Method 1620 Draft - Metals by

Inductively Coupled Plasma Atomic Emission Spectroscopy and Atomic

Absorption Spectroscopy, September 1989.

3. U.S. Environmental Protection Agency. Method 1624 Revision C - Volatile

Organic Compounds by Isotope Dilution GCMS, June 1989.

4. U.S. Environmental Protection Agency. Method 1625 Revision C - Semivolatile

Organic Compounds by Isotope Dilution GCMS, June 1989.

5. U.S. Environmental Protection Agency. Methods for Chemical Analysis of Water

and Wastes, EPA-600/4-79-020, Washington, DC, March 1979.

6. U.S. Environmental Protection Agency. Fate of Priority Pollutants in Publicly

Owned Treatment Works, EPA 440/1-82/303, Washington, DC, September, 1982.

7. U.S. Environmental Protection Agency. Report to Congress on the Discharge of

Hazardous Wastes to Publicly Owned Treatment Works, EPA 530-SW-86-004,

Washington, DC, February 1986.

8. U.S. Environmental Protection Agency. Metal Finishing F006 Benchmark Study, 

Washington, DC, September 1998.
4.0 - Industry Description

4-1

4.0 INDUSTRY DESCRIPTION

As discussed in Section 3.0, the MP&M Point Source Category covers sites that

perform manufacturing, rebuilding, or maintenance activities while processing metal parts,

machinery, or metal products. The category includes 18 industrial sectors: aerospace, aircraft,

bus and truck, electronic equipment, hardware, household equipment, instruments, job shops,

miscellaneous metal products, mobile industrial equipment, motor vehicle, office machines,

ordnance, precious metals and jewelry, printed wiring boards, railroad, ships and boats, and

stationary industrial equipment.

This section describes the MP&M industry. Section 4.1 presents an overview of

the industry; Section 4.2 provides a general discussion of unit operations performed, metal types

processed, and volumes of wastewater discharged; Section 4.3 discusses trends in the industry;

and Section 4.4 lists the references used for Section 4.

4.1 Overview of the Industry

This section discusses the MP&M industry, including the number and size of

MP&M sites, the geographic distribution of these sites, the number of wastewater discharging

sites, and the number of non-wastewater-discharging sites.

4.1.1 Number and Size of MP&M Sites

Based on the MP&M survey database, there are approximately 89,000 MP&M

sites in the United States. Based on detailed survey results, approximately 63,000 MP&M sites

discharge process wastewater. The remaining 26,000 sites fall into one of three categories: zero

dischargers, non-water-users, or contract haulers.

MP&M wastewater-discharging sites range in size from sites with less than 10

employees to sites with tens of thousands of employees, and with wastewater discharge flow

rates of less than 100 gallons per year to more than 100 million gallons per year. The following 

figure summarizes the estimated number of wastewater-discharging MP&M sites by number of

employees and estimated total discharge flow. This shows that approximately 92 percent of

MP&M sites have 500 or fewer employees and approximately 78 percent have 100 or fewer

employees. 

As shown in Figure 4-1 the number of employees at a site does not necessarily

correspond with the discharge flow at the site. [This is demonstrated by the fact that sites with

greater than 500 employees account for only 38 percent of the total industry flow.] Section 4.1.3

presents additional information on the estimated number of MP&M sites by discharge flow

range.
4.0 - Industry Description

4-2

31%

1%

40%

5%

7%

5%

14%

50%

6% 6%

2%

26%

<1%

6%

<1% (both)

0

10

20

30

40

50

60

Percentage

<=10 11-50 51-100 101-500 501-1,000 1,001-5,000 5,001-10,000 >10,000

Number of Employees

Estimated MP&M Wastewater-Discharging Sites

Estimated MP&M Discharge Flow

Source: MP&M Survey Database.

Note: There are 62,749 wastewater-discharging MP&M sites. Total MP&M wastewater flow is

122 billion gallons per year. 

Figure 4-1. MP&M Wastewater-Discharging Sites by Number of Employees

and Estimated Total Discharge Flow

4.1.2 Geographic Distribution

MP&M wastewater-discharging facilities are located throughout the United

States. EPA received survey data from all 10 EPA regions and from 48 states. MP&M facilities

are mostly concentrated in industrialized areas, with the highest concentration of facilities in

California, Pennsylvania, and Illinois. The following map shows the estimated number of

MP&M facilities located in each EPA region.
4.0 - Industry Description

4-3

Figure 4-2. Estimated Number of MP&M Facilities by EPA Region

4.1.3 Wastewater-Discharging Sites

The MP&M category includes 18 industrial sectors. Table 4-1 summarizes the

number of MP&M wastewater-discharging sites by sector. Because some sites perform

operations in more than one sector, the sum of wastewater-discharging sites by sector exceeds the

total number of wastewater-discharging sites identified in the survey. As indicated in Table 4-1,

the railroad sector has the smallest number of wastewater-discharging sites (97) and the job

shops sector has the largest number of wastewater-discharging sites (33,683). 
4.0 - Industry Description

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Table 4-1

MP&M Wastewater-Discharging Sites by Sector

Sector

Estimated Number of Sites That Discharge

Process Waste Watera

Aerospace 312

Aircraft 1,356

Bus and Truck 1,861

Electronic Equipment 2,289

Hardware 6,275

Household Equipment 2,003

Instruments 3,208

Iron and Steel c153

Job Shop b33,683

Miscellaneous Metal Products 3,030

Mobile Industrial Equipment 879

Motor Vehicle 1,506

Municipality c4,342

Office Machine 249

Ordnance 403

Precious Metals and Jewelry 307

Printed Circuit Boards 617

Railroad 97

Ships and Boats 273

Stationary Industrial Equipment 6,217

Source: MP&M Survey Database.

a Because some sites perform operations in more than one sector, the sum of sites by sector exceeds the total number

of sites that discharge water (62,749).

b The Job Shop Sector includes any MP&M facility that owns < 50% of the products they work on (annual area

basis). This includes metal finishing job shops, but also may include other job shops such as painting or assembly

job shops.

c Technical surveys for these sites did not include sector information therefore they were listed separately for this

table.

In addition to description by sector, MP&M operations can also be described by

two types of activities: manufacturing and rebuilding/maintenance. For the purpose of the

MP&M regulation, EPA defines these activities below:

C Manufacturing is the series of unit operations necessary to produce metal

products, and is generally performed in a production environment.

C Rebuilding/maintenance is the series of unit operations necessary to

disassemble used metal products into components, replace the

components or subassemblies or restore them to original function, and
4.0 - Industry Description

4-5

5%

19%

27%

75%

68%

6%

0

10

20

30

40

50

60

70

80

Percentage

Manufacturing and

Rebuilding/Maintenance

Manufacturing Only Rebuilding/Maintenance Only

Activity

Estimated MP&M WastewaterDischarging Sites

Estimated MP&M Discharge Flow 

Source: MP&M Survey Database.

Note: There are 62,749 wastewater-discharging MP&M sites. Total wastewater flow is 122 

billion gallons per year.

Figure 4-3. MP&M Wastewater-Discharging Sites and

Total Discharge Flow by Activity

reassemble the metal products. These operations are intended to keep

metal products in operating condition and can be performed in either a

production or a non-production environment.

Figure 4-3 summarizes the estimated number of MP&M wastewater-discharging

sites and baseline (i.e., current) total discharge flow by activity. The largest number of sites

(42,733) perform rebuilding/maintenance only and account for the smallest amount (6 percent) of

the total estimated discharge flow for the industry. The smallest number of sites (3,239) perform

both manufacturing and rebuilding/maintenance activities but represent 19 percent of the total

estimated discharge flow for the industry.

MP&M sites include direct dischargers, indirect dischargers, and those that are

both direct and indirect dischargers. A direct discharger is a site that discharges wastewater to a

surface water (e.g., river, lake, ocean). An indirect discharger is a site that discharges wastewater

to a publicly owned treatment works (POTW). For the purposes of the MP&M regulation, EPA

considers sites discharging exclusively to privately owned treatment works to be zero dischargers
4.0 - Industry Description

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1%

10%

7% 7%

92%

83%

0

10

20

30

40

50

60

70

80

90

100

Percentage

Direct and Indirect Direct Indirect

Discharge Destination

Estimated MP&M Wastewater-Discharging Sites

Estimated MP&M Discharge Flow 

Source: MP&M Survey Database.

Note: There are 62,749 wastewater-discharging MP&M sites. Total MP&M wastewater flow is 

122 billion gallons per year. 

Figure 4-4. MP&M Wastewater-Discharging Sites and

Total Discharge Flow by Discharge Status

that contract haul their wastewater to centralized waste treatment facilities. Figure 4-4

summarizes the number of MP&M wastewater-discharging sites and baseline total discharge

flow by discharge status. This figure shows that the majority of MP&M discharging facilities are

indirect dischargers.

Wastewater discharge flows from MP&M sites range from less than 100 gallons

per year to greater than 100 million gallons per year. Figure 4-5 summarizes the wastewater

discharge flow ranges for MP&M sites. As this figure shows, sites discharging more than one

million gallons per year (approximately 10 percent of the total sites) account for approximately

97 percent of the total wastewater discharge from the industry. In contrast, sites discharging less

than 100,000 gallons per year (approximately 72% of the total sites) account for less than 1% of

the overall wastewater discharge flow for the industry. 
4.0 - Industry Description

4-7

2%

<1%

20%

<1%

23%

<1%

27%

<1%

18%

3%

7%

14%

3%

35%

<1%

48%

0

5

10

15

20

25

30

35

40

45

50

Percentage

0-100 101-1,000 1,001-10,000 10,001-

100,000

100,001-

1,000,000

1,000,001-

10,000,000

10,000,001-

100,000,000

>100,000,000

Discharge Flow Range (GPY)

Estimated MP&M Wastewater-Discharging Sites

Estimated MP&M Discharge Flow

Source: MP&M Survey Database.

Note: There are 62,749 wastewater-discharging MP&M sites. Total MP&M wastewater flow is 

122 billion gallons per year. 

Figure 4-5. MP&M Wastewater-Discharging Sites by Total Discharge Flow

4.1.4 Non-Wastewater-Discharging Sites

Based on the results of the survey, approximately 26,000 MP&M sites do not use

process water (dry sites) or use but do not discharge process water. Based on information from

the MP&M detailed surveys, site visits, and technical literature, these sites achieve zero discharge

of process wastewater in one of the following ways:

C Contract haul all process wastewater generated on site;

C Discharge process wastewater to either on-site septic systems or deep-well

injection systems;

C Perform end-of-pipe treatment and reuse all process wastewater generated

on site;
4.0 - Industry Description

4-8

C Perform either in-process or end-of-pipe evaporation to eliminate

wastewater discharges; or

C Perform in-process recirculation and recycling to eliminate wastewater

discharges.

As discussed in Section 3.0, EPA mailed surveys to 50 statistically selected sites

that were using but not discharging process water. Based on those survey responses, five of these

sites contract hauled all wastewater generated on site, eight actually discharged process

wastewater, 18 had no process wastewater discharges, and 19 were not engaged in MP&M. EPA

mailed an additional 24 surveys, selected for technical reasons, to sites which reported not

discharging process water on their screener questionnaire. Of these, 14 actually discharged

process wastewater, two had no process wastewater discharges, and eight were not engaged in

MP&M activities. 

In addition to the 20 sites discussed above that do not discharge process

wastewater, 205 of the 1996 screener survey respondents reported eliminating wastewater

discharge by in-process or end-of-pipe evaporation, end-of-pipe treatment and reuse, in-process

recirculation and recycling, or other unspecified means. Figure 4-6 shows the number of sites

using each type of zero discharge method. Note that Figure 4-6 provides actual number of survey

respondents and not national estimates. EPA discusses the methods used by the 225 sites that

have eliminated wastewater discharges below.
4.0 - Industry Description

4-9

In-P rocess or End-O fP ip e Eva p o ratio n

41%

End- O f-P ip e 

T reatm ent and R euse

8 %

In-P rocess 

R ecirculation and

R ecy c lin g

23%

O ther

16%

U nkno w n M ethods

12%

Note: There are 225 survey sites which have eliminated wastewater discharge.

Figure 4-6. Number of Screener Survey Respondents

Utilizing Each Zero Discharge Method

In-Process or End-Of-Pipe Evaporation. Ninety-one screener survey

respondents reported discharging wastewater to either evaporators, on-site ponds, or lagoons for

evaporation of process wastewater. These sites typically performed less than 20 wastewaterdischarging unit operations. None of these sites reported recovering the process wastewater. 

Sludge from the evaporation units was reported as being contract hauled for off-site disposal. 

End-Of-Pipe Treatment and Reuse. Nineteen screener survey respondents

reported eliminating wastewater discharge through end-of-pipe treatment and reuse of all

wastewater generated on site. These sites typically performed less than 13 wastewaterdischarging unit operations on site. As discussed in Sections 9.0 and 14.0, EPA considered endof-pipe ion exchange with reuse of all wastewater generated in developing the MP&M effluent

guidelines, but determined that the technology was not appropriate for national effluent

guidelines for this industry because its effectiveness and potential metals recovery advantages

were generally limited to specific sites and specific metal types and not to the industry as a

whole. 
4.0 - Industry Description

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In-Process Recirculation and Recycling. Fifty screener survey respondents

reported eliminating wastewater discharge through in-process recirculation and recycling. Most

of these sites perform fewer than 10 wastewater-generating unit operations; five sites perform

between 10 and 20 wastewater-generating unit operations. Several sites perform heat treating

operations, in which a stagnant water quench is used and not discharged. Some sites perform

surface finishing operations (e.g., alkaline cleaning and chemical conversion coating) in stagnant

baths and do not discharge wastewater. Make-up water is added for evaporation. Based on the

data from MP&M sites, only sites with few unit operations are typically able to achieve zero

discharge solely through in-process recirculation and recycling.

Other. Thirty-seven screener survey respondents reported eliminating

wastewater discharge through a variety of other methods including land application and septic

systems.

EPA's Underground Injection Control (UIC) Program, authorized by the Safe

Drinking Water Act, regulates shallow on-site systems and deep wells that discharge fluids or

wastewater into the subsurface and thus may endanger underground sources of drinking water. If

a facility disposes any wastewater (other than solely sanitary waste) into a shallow disposal

system (e.g., septic system or a floor drain connected to a dry well) that well is covered by the

UIC program. If you think you have a UIC disposal well on your facility, you should contact

your State UIC Program authority to determine your compliance status.

EPA published the Class V Rule in the Federal Register on December 7, 1999 (64

FR 68545), which affected facilities using on-site systems to dispose waste associated with motor

vehicle service and repair in state-designated groundwater protection areas. The EPA is

scheduled to develop additional requirements for other Class V wells that receive endangering

waste. Contact your State UIC Program for more information on these developing regulations.

4.2 General Discussion of MP&M Processes

This section presents a general discussion of MP&M processes, including the

different categories of unit operations, descriptions of the unit operations performed, metal types

processed, and wastewater discharge volumes generated.

4.2.1 Types of Unit Operations Performed

MP&M sites perform a wide variety of process unit operations on metal parts,

products, and machines. The MP&M regulatory development effort initially focused on 45 unit

operations (and their associated rinses) performed at MP&M sites, plus wet air pollution control

operations. EPA describes these 46 unit operations in detail in Section 4.2.2. During the

regulatory development effort, EPA identified additional unit operations performed at MP&M

sites. Section 4.2.2 also lists these additional unit operations.
4.0 - Industry Description

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Each of the MP&M unit operations can be listed under one of the following

types: 

C Metal shaping operations;

C Surface preparation operations;

C Metal deposition operations;

C Organic deposition operations;

C Surface finishing operations;

C Assembly operations;

C Drydock operations; 

C Specialized printed wiring board operations; and

C Unit operations performed at Steel Forming and Finishing sites.

Metal shaping operations are mechanical operations that alter the form of raw

materials into intermediate and final products. Surface preparation operations are chemical and

mechanical operations that remove unwanted materials from or alter the chemical or physical

properties of the surface prior to subsequent MP&M operations. Metal deposition operations

apply a metal coating to the part surface by chemical or physical means. Organic deposition

operations apply an organic material to the part by chemical or physical means. Sites may

perform metal and organic deposition operations to protect the surface from wear or corrosion,

modify the electrical properties of the surface, or alter the appearance of the surface. Surface

finishing operations protect and seal the surface of the treated part from wear or corrosion by

chemical means. Sites may use some surface finishing operations to alter the appearance of the

part surface. Assembly operations are performed throughout the manufacturing, rebuilding, or

maintenance process. Drydock operations are those MP&M unit operations performed at ship

and boat facilities within drydocks or similar structures and incorporate many of the previously

described types of MP&M operations. Specialized printed wiring board operations are those

specific to the manufacture or rebuilding/maintenance of wiring boards (such as Carbon Black

Deposition, Solder Flux Cleaning, and Photo Image Developing). Additional unit operations

performed at Steel Forming and Finishing sites are defined in Section 14.1.5. Table 4-2 lists

example MP&M unit operations common to each type of operation described above. 
4.0 - Industry Description

4-12

Table 4-2

MP&M Unit Operations Listed by Type

Type of Unit Operation

Example Unit

Operations Performed

Metal Shaping Machining, Grinding, Deformation

Surface Preparation Alkaline Cleaning, Acid Treatment

Metal Deposition Electroplating, Vapor Deposition

Organic Deposition Painting

Surface Finishing Chemical Conversion Coating

Assembly Testing (e.g. leak testing), Assembly

Specialized Printed Wiring Board Solder Leveling, Photo Resist Applications

Unit operations performed at Steel Forming and

Finishing sites

Mechanical Descaling, Hot Dip Coating

At a given MP&M site, the specific unit operations performed and the sequence

of operations depend on many factors, including the activity (i.e., manufacturing, rebuilding/ 

maintenance), industrial sector, and type of product processed. As a result, MP&M sites perform

many different combinations and sequences of unit operations. For example, MP&M sites that

repair, rebuild or maintain products often conduct preliminary operations that may not be

performed at manufacturing facilities (e.g. disassembly, cleaning, or degreasing to remove dirt

and oil accumulated during use of the product). In general, however, MP&M products are

processed in the following order:

C The raw material (e.g., bar stock, wire, rod, sheet stock, plates) undergoes

some type of metal shaping process, such as impact or pressure

deformation, machining, or grinding. In these operations, the raw

material is shaped into intermediate forms for further processing or into

final forms for assembly and shipment to the customer. Sites typically

clean and degrease the parts between some of the shaping operations to

remove lubricants, coolants, and metal fines. Sites may also perform heat

treating operations between shaping operations to alter the physical

characteristics of the part. 

C After shaping, the part typically undergoes some type of surface

preparation operation, such as alkaline cleaning, acid pickling, or barrel

finishing. The specific operation used depends on the subsequent unit

operations to be performed and the final use of the products. For

example, prior to electroplating, parts typically undergo acid pickling (i.e.,

acid cleaning) to prepare the surface of the part for electroplating. Before

assembly, parts typically undergo alkaline cleaning or barrel finishing. 
4.0 - Industry Description

4-13

Parts undergo surface preparation operations at various stages of the

production process. Additional cleaning and degreasing steps precede

metal deposition, organic deposition, surface finishing, and assembly

operations. 

C Metal and organic deposition operations typically follow shaping and

surface preparation operations, and precede surface finishing and final

assembly operations. Electroplating operations typically follow alkaline

and acid treatment operations, while painting operations typically follow

phosphate conversion coating and alkaline treatment operations. 

C Surface finishing operations are typically performed after shaping and

surface preparation operations. Some surface finishing operations are

performed after metal deposition operations. For example, chromate

conversion coating typically follows acid cleaning, although this operation

is sometimes performed as a sealant operation after electroplating (e.g.

chemical conversion coating of cadmium plated parts). Some surface

finishing operations are also performed prior to organic coating

operations. For example, phosphate conversion coating frequently

precedes painting to enhance the paint adhesion. 

C Disassembly operations may be performed as the first step in the

rebuilding process. Assembly operations, on the other hand, are

performed at many steps of the manufacturing and rebuilding process. 

Assembly operations prepare the final product. Assembly may also

involve some final shaping (e.g., drilling and grinding) and surface

preparation (e.g., alkaline cleaning). Final assembly operations are

generally the last operations performed prior to shipment to the customer. 

Some MP&M sites conduct all of these types of operations in manufacturing or

rebuilding products, while others may perform only some types. For example, a site in the

hardware sector may start with bar stock and manufacture a final hardware product, performing

machining, cleaning, electroplating, conversion coating, painting, degreasing, and assembly

operations. Another hardware site may focus on painting the parts, and only perform cleaning

and painting operations. A third hardware site may only shape the parts, and perform only

machining, cleaning, and degreasing operations. 

4.2.2 MP&M Unit Operations and Rinses

This section describes each of the 46 MP&M unit operations listed in Table 4-3

and the wastewater generated from each operation and associated rinse. The following

descriptions are included for informational purposes and are not meant to supersede regulatory

definitions (e.g., definitions for unit operations that are part of the proposed rule are defined in

Section 14 in the applicable subcategory section).
4.0 - Industry Description

4-14

Table 4-3

Typical Unit Operations Performed at MP&M Sites

Unit Operation Name

1. Abrasive Blasting

2. Abrasive Jet Machining

3. Acid Treatment with Chromium

4. Acid Treatment without Chromium

5. Alkaline Cleaning for Oil Removal

6. Alkaline Treatment with Cyanide

7. Alkaline Treatment without Cyanide

8. Anodizing with Chromium

9. Anodizing without Chromium

10. Aqueous Degreasing

11. Assembly/Disassembly

12. Barrel Finishing

13. Burnishing

14. Chemical Conversion Coating without

Chromium

15. Chemical Milling

16. Chromate Conversion Coating

17. Corrosion Preventive Coating

18. Electrical Discharge Machining

19. Electrochemical Machining

20. Electroless Plating

21. Electrolytic Cleaning

22. Electroplating with Chromium

23. Electroplating with Cyanide

24. Electroplating without Chromium or Cyanide

25. Electropolishing

26. Floor Cleaning

27. Grinding

28. Heat Treating

29. Impact Deformation

30. Machining

31. Metal Spraying

32. Painting - Spray or Brush

33. Painting - Immersion

34. Plasma Arc Machining

35. Polishing

36. Pressure Deformation

37. Salt Bath Descaling

38. Soldering/Brazing

39. Solvent Degreasing

40. Stripping (paint)

41. Stripping (metallic coating)

42. Testing

43. Thermal Cutting

44. Washing Finished Products

45. Welding

46. Wet Air Pollution Control

Source: MP&M Survey database.

1 Abrasive Blasting involves removing surface films from a workpiece by using

abrasive directed at high velocity against the workpiece. Abrasive blasting

includes bead, grit, shot, and sand blasting, and may be performed either dry or

with water. The primary applications of wet abrasive blasting include: removing

burrs on precision parts; producing satin or matte finishes; removing fine tool

marks; and removing light mill scale, surface oxide, or welding scale. Wet

blasting can be used to finish fragile items such as electronic components. Also,

some aluminum parts are wet blasted to achieve a fine-grained matte finish for

decorative purposes. With abrasive blasting operations, the water and abrasive are

typically reused until the particle size diminishes due to impacting and fracture.

2 Abrasive Jet Machining includes removing stock material from a workpiece by a

high-speed stream of abrasive particles carried by a liquid or gas from a nozzle. 

Abrasive jet machining is used for deburring, drilling, and cutting thin sections of

metal or composite material. Unlike abrasive blasting, this process operates at
4.0 - Industry Description

4-15

pressures of thousands of pounds per square inch. The liquid streams are typically

alkaline or emulsified oil solutions, although water can also be used.

3 Acid Treatment With Chromium is a general term used to describe any

application of an acid solution containing chromium to a metal surface. Acid

cleaning, chemical etching, and pickling are types of acid treatment. 

Chromic acid is used occasionally for cleaning cast iron, stainless steel, cadmium

and aluminum, and bright dipping of copper and copper alloys. Also, chromic

acid solutions can be used as final steps in acid cleaning phosphate conversion

coating systems.

For chemical conversion coatings formulated with chromic acid, see unit

operation 16.

Wastewater generated from acid treatment includes spent solutions and rinse

waters. Spent solutions are typically batch discharged and treated or disposed of

off site. Most acid treatment operations are followed by a water rinse to remove

residual acid.

4 Acid Treatment Without Chromium is a general term used to describe any

application of an acid solution, not containing chromium, to a metal surface. Acid

cleaning, chemical etching, and pickling are types of acid treatment.

Wastewater generated from acid treatment includes spent solutions and rinse

waters. Spent solutions are typically batch discharged and treated or disposed of

off site. Most acid treatment operations are followed by a water rinse to remove

residual acid.

5 Alkaline Cleaning for Oil Removal is a general term for the application of an

alkaline cleaning agent to a metal part to remove oil and grease during the

manufacture, maintenance, or rebuilding of a metal product.

This unit operation does not include the washing of finished products after routine

use (see unit operation 44), or the application of an alkaline cleaning agent to

remove nonoily contaminants such as dirt and scale (see unit operations 6 and 7). 

Wastewater generated from this operation includes spent cleaning solutions and

rinse waters.

C Alkaline cleaning is performed to remove foreign contaminants from

parts. This process is commonly applied prior to finishing operations,

such as electroplating. 
4.0 - Industry Description

4-16

C Emulsion cleaning is an alkaline treatment (typically performed in the pH

range of 7 to 9) that uses either complex chemical enzymes or common

organic solvents (e.g., kerosene, mineral oil, glycols, and benzene)

dispersed in water with the aid of an emulsifying agent. Depending on the

solvent used, cleaning is performed at temperatures from room

temperature to 82EC (180EF). The process is often used as a replacement

for vapor degreasing.

6 Alkaline Treatment With Cyanide is a general term used to describe the

application of an alkaline solution containing cyanide to a metal surface to clean

it.

Wastewater generated from alkaline treatment includes spent solutions and rinse

waters. Alkaline treatment solutions become contaminated during use from the

introduction of soils and/or dissolution of the base metal, and they are typically

batch discharged for treatment or disposal. Alkaline treatment operations are

typically followed by a water rinse that is discharged to treatment. EPA does not

consider the washing of finished products after routine use to be part of this unit

operation, but instead classifies this as unit operation 44, washing of finished

products. 

7 Alkaline Treatment Without Cyanide is a general term used to describe the

application of an alkaline solution, not containing cyanide, to a metal surface to

clean the metal surface or prepare the metal surface for further surface finishing. 

Alkaline treatment includes alkaline cleaning and emulsion cleaning as described

under unit operation 5.

8 Anodizing With Chromium involves producing a protective oxide film on

aluminum, magnesium, or other light metal, usually by passing an electric current

through an electrolyte bath in which the metal is immersed. Anodizing may be

followed by a sealant operation.

Chromic acid anodic coatings have a relatively thick boundary layer and are more

protective than sulfuric acid coatings. For these reasons, chromic acid is

sometimes used when the part cannot be completely rinsed. These oxide coatings

provide corrosion protection, decorative surfaces, a base for painting and other

coating processes, and special electrical and mechanical properties.

Wastewater generated from anodizing includes spent anodizing solutions,

sealants, and rinse waters. Because of the anodic nature of the process, anodizing

solutions become contaminated with the base metal being processed. These

solutions eventually reach an intolerable concentration of dissolved metal and

require treatment or disposal. Rinse water following anodizing, coloring, and

sealing steps is typically discharged to treatment.
4.0 - Industry Description

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9 Anodizing Without Chromium involves producing of a protective oxide film on

aluminum, magnesium, or other light metal, usually by passing an electric current

through an electrolyte bath in which the metal is immersed. Phosphoric acid,

sulfuric acid, and boric acid, are all types of anodizing. Anodizing may also

include sealant baths. These oxide coatings provide corrosion protection,

decorative surfaces, a base for painting and other coating processes, and special

electrical and mechanical properties.

Wastewater generated from anodizing includes spent anodizing solutions,

sealants, and rinse waters. Because of the anodic nature of the process, anodizing

solutions become contaminated with the base metal being processed. These

solutions eventually reach an intolerable concentration of dissolved metal and

require treatment or disposal. Rinse water following anodizing, coloring, and

sealing steps typically discharged to treatment.

10 Aqueous Degreasing involves cleaning metal parts using aqueous-based cleaning

chemicals primarily to remove residual oils and greases from a part. Residual oils

can be from previous operations (e.g., machine coolants), oil from product use in

a dirty environment, or oil coatings intended to inhibit corrosion. Wastewater

generated by this operation includes spent cleaning solutions and rinse waters.

11 Assembly/Disassembly involves fitting together previously manufactured or

rebuilt parts or components into a complete metal product or machine or taking a

complete metal product or machine apart. Assembly/disassembly operations are

typically dry; however, special circumstances can require water for cooling or

buoyancy. Also, rinsing may be necessary under some conditions.

12 Barrel Finishing (i.e., tumbling, mass finishing) involves polishing or deburring

a workpiece using a rotating or vibrating container and abrasive media or other

polishing materials to achieve a desired surface appearance. Parts to be finished

are placed in a rotating barrel or vibrating unit with an abrasive media (e.g.,

ceramic chips, pebbles), water, and chemical additives (e.g., alkaline detergents). 

As the barrel rotates, the upper layer of the part slides toward the lower side of the

barrel, causing the abrading or polishing. Similar results can also be

accomplished in a vibrating unit, where the entire contents of the container are in

constant motion, or in a centrifugal unit, which compacts the load of media and

parts as the unit spins and generates up to 50 times the force of gravity. Spindle

finishing is a similar process, where parts to be finished are mounted on fixtures

and exposed to a rapidly moving abrasive slurry.

Wastewater generated by barrel finishing includes spent process solutions and

rinses. Following the finishing process, the contents of the barrel are unloaded. 

Process wastewater is either discharged continuously during the process,
4.0 - Industry Description

4-18

discharged after finishing, or collected and reused. The parts are sometimes given

a final rinse to remove particles of abrasive media from part surfaces.

13 Burnishing involves finish sizing or smooth finishing a workpiece (previously

machined or ground) by displacing, rather than removing, minute surface

irregularities with smooth point or line-contact, fixed or rotating tools. Lubricants

or soap solutions can be used to cool tools used in burnishing operations. 

Wastewater is generated from burnishing operations through process solution

discharges and rinsing.

14 Chemical Conversion Coating without Chromium is the process of applying a

protective coating on the surface of a metal without using chromium. Such

coatings include metal phosphates, metal coloring, passivation, or other coatings. 

These coatings are applied to a base metal or previously deposited metal to

increase corrosion protection and lubricity, prepare the surface for additional

coatings, or formulate a special surface appearance. This unit operation includes

sealant operations using additives other than chromium.

C Phosphate conversion coatings are applied for one or more of the

following reasons: to provide a base for paints and other organic coatings;

to condition surfaces for cold forming operations by providing a base for

drawing compounds and lubricants; to impart corrosion resistance to the

metal surface; or to provide a suitable base for corrosion-resistant oils or

waxes. Phosphate conversion coatings are formed by immersing a metal

part in a dilute solution of phosphoric acid, phosphate salts, and other

reagents.

C Metal coloring by chemical conversion coating produces a large group of

decorative finishes. Metal coloring includes the formation of oxide

conversion coatings. In this operation, the metal surface is converted into

an oxide or similar metallic compound, giving the part the desired color. 

The most common colored finishes are used on copper, steel, zinc, and

cadmium.

C Passivation forms a protective film on metals, particularly stainless steel,

by immersing parts in an acid solution. Stainless steel is passivated to

dissolve embedded iron particles and to form a thin oxide film on the

surface of the metal.

Wastewater generated by chemical conversion coating operations includes spent

process solutions and rinses (i.e., both the chemical conversion coating solutions

and post-treatment sealant solutions). These solutions are commonly discharged

to treatment when contaminated with the base metal or other impurities. Rinsing
4.0 - Industry Description

4-19

normally follows each process step, except after some sealants, which dry on the

part surface.

15 Chemical Milling (or Chemical Machining) involves removing metal from a

workpiece by controlled chemical attack, or etching, to produce desired shapes

and dimensions. In chemical machining, a masking agent is typically applied to

cover a portion of the part's surface; the exposed (unmasked) surface is then

treated with the chemical machining solution.

Wastewater generated by chemical machining operations includes spent process

solutions and rinses. Process solutions are commonly discharged after becoming

contaminated with the base metal. Rinsing normally follows chemical machining.

16 Chromate Conversion Coating (or chromating) involves forming a conversion

coating (protective coating) on a metal by immersing or spraying the metal with a

hexavalent chromium compound solution to produce a hexavalent and/or trivalent

chromium compound coating. This is also known as chromate treatment, and is

most often applied to aluminum, zinc, cadmium or magnesium surfaces. Sealant

operations using chromium are also included in this unit operation.

Chromate solutions include two types: (1) those that deposit substantial chromate

films on the substrate metal and are complete treatments themselves, and (2) those

that seal or supplement oxide, phosphate, or other types of protective coatings.

Wastewater generated by chromate conversion coating operations includes spent

process solutions (i.e., both the chromate conversion coating solutions and posttreatment sealant solutions) and rinses. These solutions are commonly discharged

to treatment when contaminated with the base metal or other impurities. Also,

chromium-based solutions, which are typically formulated with hexavalent

chromium, lose operating strength when the hexavalent chromium reduces to

trivalent chromium during use. Rinsing normally follows each process step,

except after some sealants, which dry on the surface of the part.

17 Corrosion Preventive Coating involves applying removable oily or organic

solutions to protect metal surfaces against corrosive environments. Corrosion

preventive coatings include, but are not limited to: petrolatum compounds, oils,

hard dry-film compounds, solvent-cutback petroleum-based compounds,

emulsions, water-displacing polar compounds, and fingerprint removers and

neutralizers. Corrosion preventive coating does not include electroplating or

chemical conversion coating (including phosphate conversion coating) operations.

Many corrosion preventive materials are also formulated to function as lubricants

or as a base for paint. Typical applications include: assembled machinery or

equipment in standby storage; finished parts in stock or spare parts for
4.0 - Industry Description

4-20

replacement; tools such as drills, taps, dies, and gauges; and mill products such as

sheet, strip, rod and bar.

Wastewater generated from corrosion preventive coating operations includes

spent process solutions and rinses. Process solutions are discharged when they

become contaminated with impurities or are depleted of constituents. Corrosion

preventive coatings do not typically require an associated rinse, but parts are

sometimes rinsed to remove the coating before further processing.

18 Electrical Discharge Machining involves removing metals by a rapid spark

discharge between different polarity electrodes, one the workpiece and the other

the tool, separated by a small gap. The gap may be filled with air or a dielectric

fluid. This operation is used primarily to cut tool alloys, hard nonferrous alloys,

and other hard-to-machine materials. Most electrical discharge machining

processes are operated dry. In some cases, water is used in the process, which

generates wastewater of water-based dielectric fluids.

19 Electrochemical Machining is a process in which the workpiece becomes the

anode and a shaped cathode is the cutting tool. By pumping electrolyte between

the electrodes and applying a potential, metal is rapidly but selectively dissolved

from the workpiece. Wastewater generated by electrochemical machining

includes spent electrolytes and rinses.

20 Electroless Plating involves deposition of a metallic coating by a controlled

chemical reduction that is catalyzed by the substitute material being deposited

without using an electrical current. The metal to be plated onto a part is typically

held in solution at high concentrations by the use of a chelating agent. This

operation plates all areas of the part to a uniform thickness regardless of the

configuration of the part. Also, an electroless-plated surface is dense and virtually

nonporous. Copper and nickel electroless plating are the most common.

Sealant operations (i.e., other than hot water dips) performed following this

operation are considered separate unit operations if they include any additives.

Wastewater generated from electroless plating operations includes spent process

solutions and rinses. This wastewater contain chelated metals, which require

separate preliminary treatment to break the metal chelates prior to conventional

chemical precipitation. Rinsing follows most electroless plating processes to

remove residual plating solution and prevent contamination of subsequent process

baths. 

21 Electrolytic Cleaning involves removing soil, scale, or surface oxides from a

workpiece by electrolysis. The workpiece is one of the electrodes and the
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electrolyte is usually alkaline. Electrolytic alkaline cleaning and electrolytic acid

cleaning are the two types of electrolytic cleaning. They are described below.

C Electrolytic alkaline cleaning produces a cleaner surface than

nonelectrolytic methods of alkaline cleaning. This method uses strong

agitation, gas evolution in the solution, and oxidation-reduction reactions

that occur during electrolysis. In addition, dirt particles become

electrically charged and are repelled from the part surface.

C Electrolytic acid cleaning is sometimes used as a final cleaning before

electroplating. Sulfuric acid is most frequently used as the electrolyte. As

with electrolytic alkaline cleaning, the mechanical scrubbing effect from

the evolution of gas enhances the effectiveness of the process.

Wastewater generated from electrolytic cleaning operations includes spent process

solutions and rinses. Electrolytic cleaning solutions become contaminated during

use due to the base metal dissolving and the introduction of contaminants. The

solution is typically batch discharged for treatment or disposal after it weakens. 

Following electrolytic cleaning, rinsing is used to remove residual cleaner and

prevent the contamination of subsequent process baths.

22 Electroplating with Chromium involves producing a chromium metal coating

on a surface by electrodeposition. Electroplating provides corrosion protection,

wear or erosion resistance, lubricity, electrical conductivity, or decoration.

In electroplating, metal ions in acid, alkaline, or neutral solutions are reduced on

the cathodic surfaces of the parts being plated. Metal salts or oxides are typically

added to replenish solutions. Chromium trioxide is often added as a source of

chromium.

In addition to water and the metal being deposited, electroplating solutions often

contain agents that form complexes with the metal being deposited, stabilizers to

prevent hydrolysis, buffers for pH control, catalysts to assist in deposition,

chemical aids to dissolve anodes, and miscellaneous ingredients that modify the

process to attain specific properties. Sealant operations (i.e., other than hot water

dips) performed after this operation are considered separate unit operations if they

include any additives.

Wastewater generated from electroplating operations includes spent process

solutions and rinses. Electroplating solutions occasionally become contaminated

during use due to the base metal dissolving and/or the introduction of other

contaminants. As this happens, the performance of the electroplating solutions

diminishes. Spent concentrated solutions are typically treated for contaminant

removal and reused, processed in a wastewater treatment system, or sent off site
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for disposal. Rinse waters, including some drag-out rinse tank solutions, are

typically treated on site.

23 Electroplating with Cyanide involves producing metal coatings on a surface by

electrodeposition, using cyanide. Electroplating provides corrosion protection,

wear or erosion resistance, lubricity, electrical conductivity, or decoration.

In electroplating, metal ions in acid, alkaline, or neutral solutions are reduced on

the cathodic surfaces of the parts being plated. The metal ions in solution are

typically replenished by dissolving metal from anodes contained in inert wire or

metal baskets. Sealant operations performed after this operation are considered

separate unit operations if they include any additives (i.e., any sealant operations

other than hot water dips).

In addition to water and the metal being deposited, electroplating solutions often

contain agents that form complexes with the metal being deposited, stabilizers to

prevent hydrolysis, buffers for pH control, catalysts to assist in deposition,

chemical aids for dissolving anodes, and miscellaneous ingredients that modify

the process to attain specific properties. Cyanide, usually in the form of sodium

or potassium cyanide, is frequently used as a complexing agent for zinc, cadmium,

copper, and precious metal baths.

Wastewater generated from electroplating operations includes spent process

solutions and rinses. Electroplating solutions occasionally become contaminated

during use due to dissolution of the base metal and/or the introduction of other

contaminants. As this happens, the performance of the electroplating solutions

diminishes. Spent concentrated solutions are typically treated for contaminant

removal and reused, processed in a wastewater treatment system, or sent off site

for disposal. Rinse waters, including some drag-out rinse tank solutions, are

typically treated on site.

24 Electroplating without Chromium or Cyanide involves the production of metal

coatings on a surface by electrodeposition, without the use of chromium or

cyanide. Commonly electroplated metals include nickel, copper, tin/lead, gold,

and zinc. Electroplating is performed to provide corrosion protection, wear or

erosion resistance, lubricity, electrical conductivity, or decoration.

In electroplating, metal ions in acid, alkaline, or neutral solutions are reduced on

the cathodic surfaces of the parts being plated. The metal ions in solution are

typically replenished by dissolving metal from anodes contained in inert wire or

metal baskets. Sealant operations performed after this operation are considered

separate unit operations if they include any additives (i.e., any sealant operations

other than hot water dips).
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In addition to water and the metal being deposited, electroplating solutions often

contain agents that form complexes with the metal being deposited, stabilizers to

prevent hydrolysis, buffers for pH control, catalysts to assist in deposition,

chemical aids for dissolving anodes, and miscellaneous ingredients that modify

the process to attain specific properties.

Wastewater generated from electroplating operations includes spent process

solutions and rinses. Electroplating solutions occasionally become contaminated

during use due to dissolution of the base metal and/or the introduction of other

contaminants. As this happens, the performance of the electroplating solutions

diminishes. Spent concentrated solutions are typically treated for contaminant

removal and reused, processed in a wastewater treatment system, or sent off site

for disposal. Rinse waters, including some drag-out rinse tank solutions, are

typically treated on site.

25 Electropolishing involves producing a highly polished surface on a workpiece

using reversed electrodeposition in which the anode (workpiece) releases some

metal ions into the electrolyte to reduce surface roughness. When current is

applied, a polarized film forms on the metal surface, through which metal ions

diffuse. In this process, areas of surface roughness on parts serve as high-current

density areas and are dissolved at rates greater than the smoother portions of the

metal surface.

Metals are electropolished to improve appearance, reflectivity, and corrosion

resistance. Base metals processed by electropolishing include aluminum, copper,

zinc, low-alloy steel, and stainless steel. Common electrolytes include sodium

hydroxide and combinations of sulfuric acid, phosphoric acid, and chromic acid.

Wastewater generated from electropolishing operations includes spent process

solutions and rinses. Eventually, the concentration of dissolved metals increases

beyond tolerable levels and the process becomes ineffective. Typically, a portion

of the bath is decanted and some fresh chemicals are added, or the entire solution

is discharged to treatment and replaced with fresh chemicals. Rinsing can involve

several steps and can include hot immersion or spray rinses.

26 Floor Cleaning (in process area) removes dirt, debris, process solution spills,

etc., from process area floors. Floors can be cleaned using wet or dry methods,

such as vacuuming, mopping, dry sweeping, and hose rinsing. Nonprocess area

floor cleaning in offices and other areas is not included in this unit operation.

27 Grinding involves removing stock from a workpiece by using abrasive grains

held by a rigid or semirigid binder. Grinding shapes or deburrs the workpiece.
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The grinding tool is usually a disk (the basic shape of grinding wheels), but can

also be a cylinder, ring, cup, stick, strip, or belt. The most commonly used

abrasives are aluminum oxide, silicon carbide, and diamond. The process may

use a grinding fluid to cool the part and remove debris or metal fines.

Wastewater generated from grinding operations includes spent coolants and

rinses. Metal-working fluids become spent for a number of reasons, including

increased biological activity (i.e., the fluids become rancid) or decomposition of

the coolant additives. Rinse waters are typically assimilated into the working

fluid or treated on site.

28 Heat Treating involves modifying the physical properties of a workpiece by

applying controlled heating and cooling cycles. This operation includes tempering, carburizing, cyaniding, nitriding, annealing, aging, normalizing, austenitizing,

austempering, siliconizing, martempering, and malleablizing. Parts are heated in

furnaces or molten salt baths, and then may be cooled by quenching in aqueous

solutions (e.g., brine solutions), neat oils (pure oils with little or no impurities), or

oil/water emulsions. Heat treating is typically a dry operation. It is considered a

wet operation if aqueous quenching solutions are used. Wastewater can be

generated from spent quench water and rinses.

29 Impact Deformation involves applying impact force to a workpiece to

permanently deform or shape it. Impact deformation may include mechanical

operations such as hammer forging, shot peening, peening, coining, high-energyrate forming, heading, or stamping.

Impact deformation operations use natural and synthetic oils, light greases, and

pigmented lubricants. Pigmented lubricants include whiting, lithapone, mica, zinc

oxide, molybdenum disulfide, bentonite, flour, graphite, white lead, and soap-like

materials.

These operations are typically dry, but wastewater can be generated from lubricant

discharge and from rinsing operations associated with the process.

30 Machining involves removing stock from a workpiece (as chips) by forcing a

cutting tool against the workpiece. This definition includes machining operations

such as turning, milling, drilling, boring, tapping, planing, broaching, sawing,

cutoff, shaving, shearing, threading, reaming, shaping, slotting, hobbing, and

chamfering. Machining operations use various types of metal working fluids, the

choice of which depends on the type of machining being performed and the

preference of the machine shop. The fluids can be categorized into four groups: 

straight oil (neat oils), synthetic, semisynthetic, and water-soluble oil.
4.0 - Industry Description

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Machining operations generate wastewater from working fluid or rinse water

discharge. Metal working fluids are periodically discarded because of reduced

performance or development of a rancid odor. After machining, parts are

sometimes rinsed to remove coolant and metal chips. The coolant reservoir is

sometimes rinsed, and the rinse water is added to the working fluid.

31 Metal Spraying (including water curtain) involves applying a metallic coating

to a workpiece by projecting molten or semimolten metal particles onto a

substrate. Coatings can be sprayed from rod or wire stock or from powdered

material. The process involves feeding the material (e.g., wire) into a flame where

it is melted. The molten stock is then stripped from the end of the wire and

atomized by a high-velocity stream of compressed air or other gas, which propels

the material onto a prepared substrate or part.

Metal spraying coatings are used in a wide range of special applications,

including: insulating layers in applications such as induction heating coils;

electromagnetic interference shielding; thermal barriers for rocket engines;

nuclear moderators; films for hot isostatic pressing; and dimensional restoration

of worn parts.

Metal spraying is sometimes performed in front of a “water curtain” (a circulated

water stream used to trap overspray) or a dry filter exhaust hood that captures the

overspray and fumes. With water curtain systems, water is recirculated from a

sump or tank. Wastewater is generated when the sump or tank is periodically

discharged. Metal spraying is not typically followed by rinsing.

32 Painting-Spray or Brush (including water curtains) involves applying an

organic coating to a workpiece. The application of coatings such as paint,

varnish, lacquer, shellac and plastics uses processes such as spraying, brushing,

roll coating, lithographing, powder coating, and wiping.

Water is used in painting operations as a solvent (water-borne formulations) for

rinsing, for cleanup, and for water-wash (or curtain) type spray booths. Paint

spray booths typically use most of the water in this unit operation. Spray booths

capture overspray (i.e., paint that misses the product during application), and

control the introduction of contaminants to the workplace and environment.

33 Painting-Immersion (including electrophoretic, “e-coat”) involves applying an

organic coating to a workpiece using technology-based processes such

autophoretic and electrophoretic painting, described below.

C Autophoretic Painting is the application by nonelectrophoresis of an

organic paint film when a workpiece is immersed in a suitable aqueous

bath.
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C Electrophoretic Painting is coating a workpiece by making it either

anodic or cathodic in a bath that is generally an aqueous emulsion of the

organic coating material.

C Other Immersion Painting includes all other types of immersion painting

such as dip painting.

Water is used in immersion paint operations as a carrier for paint particles and to

rinse the part. Aqueous painting solutions and rinses are typically treated through

an ultrafiltration system. The concentrate is returned to the painting solution, and

the permeate is reused as rinse water. Sites typically discharge a bleed stream to

treatment. The painting solution and rinses are periodically batch-discharged to

treatment. 

34 Plasma Arc Machining involves material removal or shaping of a workpiece by a

high-velocity jet of high-temperature, ionized gas. In plasma arc machining, a gas

(nitrogen, argon, or hydrogen) is passed through an electric arc, causing the gas to

become ionized, and heated to temperatures exceeding 16,650EC (30,000EF). The

relatively narrow plasma jet melts and displaces the material in its path. Because

plasma machining does not depend on a chemical reaction between the gas and

the part, and because plasma temperatures are extremely high, the process can be

used on almost any metal, including those that are resistant to oxygen-fuel gas

cutting. The method is used mainly for profile cutting of stainless steel and

aluminum alloys.

Although plasma arc machining is typically a dry process, water is used for water

injection plasma arc torches. In these cases, a constricted swirling flow of water

surrounds the cutting arc. This operation may also be performed immersed in a

water bath. In both cases, the water is used to stabilize the arc, to cool the part,

and to contain smoke and fumes.

35 Polishing involves removing stock from a workpiece by the action of loose or

loosely held abrasive grains carried to the workpiece by a flexible support. 

Usually, the amount of stock removed in a polishing operation is only incidental

to achieving a desired surface finish or appearance. Buffing is included in the

polishing unit operation. It is usually performed using a revolving cloth or sisal

buffing wheel, which is coated with a suitable compound. Liquid buffing

compounds are used extensively for large-volume production on semiautomated

or automated buffing equipment. Polishing operations are typically dry, although

some operations are performed with liquid compounds or associated rinses.

36 Pressure Deformation involves applying force (other than impact force) to

permanently deform or shape a workpiece. Pressure deformation operations may
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include operations such as rolling, drawing, bending, embossing, sizing,

extruding, squeezing, spinning, necking, forming, crimping or flaring.

Natural and synthetic oils, light greases, and pigmented lubricants are used in

pressure deformation operations. Pigmented lubricants include whiting,

lithapone, mica, zinc oxide, molybdenum disulfide, bentonite, flour, graphite,

white lead, and soap-like materials.

Pressure deformation is typically dry, but wastewater is sometimes generated from

the discharge of lubricants or from rinsing operations associated with the process.

37 Salt Bath Descaling involves removing surface oxides or scale from a workpiece

by immersion of the workpiece in a molten salt bath or hot salt solution. Salt bath

descaling solutions can contain molten salts, caustic soda, sodium hydride, and

chemical additives. Molten salt baths are used in a salt bath-water quench-acid

dip sequence to remove oxides from stainless steel and other corrosion-resistant

alloys. In this process, the part is typically immersed in the molten salt, quenched

with water, and then dipped in acid. Oxidizing, reducing, or electrolytic salt baths

can be used depending upon the oxide to be removed. Wastewater generated from

salt bath descaling operations includes spent process solutions, quenches, and

rinses.

38 Soldering involves joining metals by inserting a thin (capillary thickness) layer of

nonferrous filler metal into the space between them. Bonding results from the

intimate contact produced by the metallic bond formed between the substrate

metal and the solder alloy. The term soldering is used where the melting temperature of the filler is below 425EC (800EF). Some soldering operations use a

solder flux, which is an aqueous or nonaqueous material used to dissolve, remove,

or prevent the formation of surface oxides on the part.

Except for the use of aqueous fluxes, soldering is typically a dry operation;

however, a quench or rinse sometimes follows soldering to cool the part or

remove excess flux or other foreign material from its surface. Recent

developments in soldering technology have focused on fluxless solders and fluxes

that can be cleaned off with water.

39 Solvent Degreasing removes oils and grease from the surface of a part by using

organic solvents, including aliphatic petroleum (e.g., kerosene, naphtha),

aromatics (e.g., benzene, toluene), oxygenated hydrocarbons (e.g., ketones,

alcohol, ether), and halogenated hydrocarbons (e.g., 1,1,1-trichloroethane,

trichloroethylene, methylene chloride).

Solvent cleaning can be accomplished in either the liquid or vapor phase. Solvent

vapor degreasing is normally quicker than solvent liquid degreasing. However,
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ultrasonic vibration is sometimes used with liquid solvents to decrease the

required immersion time with complex shapes. Solvent cleaning is often used as

a precleaning operation prior to alkaline cleaning, as a final cleaning of precision

parts, or as a surface preparation for some painting operations. Solvent

degreasing operations are typically not followed by rinsing, although rinsing is

performed in some cases.

40 Stripping (paint) involves removal of a paint (or other organic) coating from a

metal basis material. Stripping is commonly performed as part of the

manufacturing process to recover parts that have been improperly coated or as a

part of maintenance and rebuilding to restore parts to a usable condition.

Organic coatings (including paint) are stripped using thermal, mechanical, and

chemical means. Thermal methods include burn-off ovens, fluidized beds of

sand, and molten salt baths. Mechanical methods include scraping and abrasive

blasting (see unit operation 1). Chemical paint strippers include alkali solutions,

acid solutions, and solvents (e.g., methylene chloride).

Wastewater generated from organic coating stripping operations includes process

solutions (limited mostly to chemical paint strippers and rinses).

41 Stripping (metallic coating) involves removing a metallic coating from a metal

basis material. Stripping is commonly performed as part of the manufacturing

process to recover parts that have been improperly coated or as a part of

maintenance and rebuilding to restore parts to a usable condition.

Metallic coating stripping most often uses chemical baths, although mechanical

means (e.g., grinding, abrasive blasting) are also used. Chemical stripping is

frequently performed as an aqueous electrolytic process.

Wastewater generated from metallic coating stripping operations includes process

solutions and rinses. Stripping solutions become contaminated due to dissolution

of the base metal. Typically, the entire solution is discharged to treatment. 

Rinsing is used to remove the corrosive film remaining on the parts.

42 Testing involves application of thermal, electrical, mechanical, hydraulic, or other

energy to determine the suitability or functionality of a part, assembly or complete

unit. Testing may also include the application of surface penetrant dyes to detect

surface imperfections. Other types of tests frequently performed, which are

typically dry but may generate wastewater under certain circumstances, include

electrical testing, performance testing, X-ray testing, and ultrasonic testing. 

Testing is usually performed to replicate some aspect of the working environment. 

Wastewater generated from testing operations includes spent process solutions

and rinses.
4.0 - Industry Description

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43 Thermal Cutting involves cutting, slotting or piercing a workpiece using an oxyacetylene oxygen lance, electric arc cutting tool, or laser. Thermal cutting is

typically a dry process, except for the use of contact cooling waters and rinses.

44 Washing (finished products) involves the cleaning of finished metal products

after use or storage. This includes the use of fresh water or water containing a

mild cleaning solution. This unit operation applies only to the finished products

that do not require maintenance or rebuilding.

45 Welding involves joining two or more pieces of material by applying heat,

pressure, or both, with or without filler material, to produce a metallurgical bond

through fusion or recrystallization across the interface. Included in this definition

are gas welding, resistance welding, arc welding, cold welding, electron beam

welding, and laser beam welding. Welding is typically a dry process, except for

the occasional use of contact cooling waters or rinses.

46 Wet Air Pollution Control involves the use of water to remove chemicals,

fumes, or dusts that are entrained in air streams exhausted from process tanks or

production areas. Most frequently, wet air pollution control devices are applied to

electroplating, cleaning, and coating processes. A common type of wet air

pollution control is the wet packed scrubber consisting of a spray chamber that is

filled with packing material. Water is continuously sprayed onto the packing and

the air stream is pulled through the packing by a fan. Contaminants in the air

stream are absorbed by the water droplets and the air is released to the

atmosphere. A single scrubber often serves numerous process tanks; however, the

air streams are typically segregated by source into chromium, cyanide, and

acid/alkaline sources.

Table 4-4 lists the less common unit operations identified from MP&M detailed

surveys. Descriptions of these unit operations are contained in the public record for this

rulemaking. Wastewater discharge flow from these operations represents less than 3 percent of

the industry flow. Descriptions of unit operations applicable to the Steel Forming and Finishing

Subcategory are listed in Section 14.1.5.
4.0 - Industry Description

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Table 4-4

Additional Water-Using Unit Operations Performed at MP&M Sites

Unit Operation Name a

Number of

Facilities

Performing

Unit Operation Unit Operation Name a

Number of

Facilities

Performing

Unit Operation

Acid Pickling Neutralization 35 Mechanical Plating 127

Adhesive Bonding 101 Multiple Unit Operation Rinse 462

Bilge Water 13 Phosphor Deposition 7

Calibration 33 Photo Image Developing 688

Carbon Black Deposition 73 Photo Imaging 7

Chromium Drag-out Reduction 6 Photo Resist Applications 20

Cyanide Rinsing 13 Solder Flux Cleaning 248

Dry Dock/Stormwater 21 Solder Fusing 144

Galvanizing/Hot Dip Coating 93 Steam Cleaning 22

Hot Dip Coating 63 Thermal Infusion 37

Kerfing 15 Vacuum Impregnation 51

Laundering 75 Water Shedder 12

Source: MP&M Survey database.

a EPA identified these unit operations based on responses to the 1989 and 1996 detailed survey mailouts.

4.2.3 Metal Types Processed

MP&M sites perform unit operations on a variety of metal types. Survey results

identified 29 different metal types that are processed at MP&M sites. Of these, iron, aluminum,

and copper are the base metals most frequently processed. Nickel, tin, lead, gold, and zinc are

frequently processed as metals electroplated onto base metals. 

Many MP&M sites also process more than one metal type on site. Figure 4-7

shows the percent of wastewater-discharging sites by number of metal types processed. As

shown in Figure 4-7, more than half of the wastewater-discharging MP&M sites process more

than one metal type on site. 
4.0 - Industry Description

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Z e ro M eta l T ypes

15%

One Me ta l T yp e

Two M eta l T ypes 32%

37%

T h ree Me t a l T ypes

8 %

F o u r M e t a l T ypes

2 %

F ive o r M o re Me t a l T ypes

6 %

Source: MP&M Survey Database.

Note: There are 62,749 wastewater - discharging MP&M sites. Zero metal types represent sites

discharging process water only from floor cleaning of the metals processing area.

Figure 4-7. Number of MP&M Wastewater-Discharging Sites

by Number of Metal Types Processed

4.2.4 Wastewater Discharge Volumes Generated

Process wastewater is used in many of the unit operations listed in Section 4.2.2. 

Some operations may be performed with and without water (wet or dry) depending on the

purpose of the operation, raw materials, and final product use. For example, some machining

operations (e.g., drilling) can often be performed without a coolant, while other machining

operations (e.g., milling) typically require a coolant. Process wastewater may be recirculated,

recycled or reused by one of the zero-wastewater-discharge methods described in Section 4.1.4,

however, process wastewater is generally discharged to treatment or disposal. 

Based on survey results, the most commonly performed wet unit operations are

floor cleaning and acid treatment. Survey results also show the most commonly performed unit

operations are not the ones generating the largest volumes of wastewater. Of the wastewater

discharged, 79 percent is generated from associated rinses, with chemical conversion coating

rinsing, acid treatment rinsing, and alkaline treatment rinsing generating the most wastewater. 

Table 4-5 summarizes which operations are typically performed without water, the number of

MP&M sites that discharge process wastewater from each unit operation, and the total industry

discharge flow from each unit operation.
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Table 4-5

Number of MP&M Sites Discharging Process Wastewater

by Unit Operation and Flowa

Survey Unit

Operation

Number Unit Operation Description

Typically

Performed

Dry

Estimated Number of

MP&M Sites

Discharging

Wastewater from Unit

Operation

Total Estimated Industry

Discharge Flow from Unit

Operationb

(gpy)

1 Abrasive Blasting T 609 38,778,160

1R. Abrasive Blasting Rinse 667 305,528,295

2 Abrasive Jet Machining T 1,072 39,977,953

3 Acid Treatment With Chromium 351 4,086,562

3R. Acid Treatment With Chromium

Rinse

429 364,766,772

4 Acid Treatment Without

Chromium

5,690 416,840,116

4R. Acid Treatment Without

Chromium Rinse

6,574 17,754,706,129

5 Alkaline Cleaning for Oil Removal 6,253 1,401,562,927

5R. Alkaline Cleaning for Oil Removal

Rinse

4,400 8,625,499,609

6 Alkaline Treatment With Cyanide 204 4,729,476

6R. Alkaline Treatment With Cyanide

Rinse

252 74,087,698

7 Alkaline Treatment Without

Cyanide

5,667 556,356,897

7R. Alkaline Treatment Without

Cyanide Rinse

4,185 7,906,960,561

8 Anodizing With Chromium 183 398,976

8R. Anodizing With Chromium Rinse 194 205,226,036

9 Anodizing Without Chromium 577 12,858,977

9R. Anodizing Without Chromium

Rinse

678 4,120,542,720

10 Aqueous Degreasing 19,148 637,940,485

10R. Aqueous Degreasing Rinse 13,718 631,789,542

11 Assembly/Disassembly T 960 62,328,594

11R. Assembly/Disassembly Rinse 836 2,086,711

12 Barrel Finishing 6,639 1,481,495,528

12R. Barrel Finishing Rinse 2,820 596,393,341

13 Burnishing 2,311 137,710,275

13R. Burnishing Rinse 1,447 333,474,479
Table 4-5 (Continued)

4.0 - Industry Description

Survey Unit

Operation

Number Unit Operation Description

Typically

Performed

Dry

Estimated Number of

MP&M Sites

Discharging

Wastewater from Unit

Operation

Total Estimated Industry

Discharge Flow from Unit

Operationb

(gpy)

4-33

14 Chemical Conversion Coating

Without Chromium

4,387 1,231,117,839

14R. Chemical Conversion Coating

Without Chromium Rinse

4,815 25,297,218,112

15 Chemical Milling 726 43,500,663

15R. Chemical Milling Rinse 1,258 1,095,828,156

16 Chromate Conversion Coating 1,900 73,476,786

16R. Chromate Conversion Coating

Rinse

2,115 2,146,579,879

17 Corrosion Preventive Coating T 924 69,973,819

17R. Corrosion Preventive Coating

Rinse

463 686,365,140

18 Electrical Discharge Machining 729 1,714,162

18R Electrical Discharge Machining

Rinse

279 3,368,478

19 Electrochemical Machining 189 349,183,003

19R. Electrochemical Machining Rinse 165 43,572,599

20 Electroless Plating 1,256 18,175,581

20R. Electroless Plating Rinse 1,646 665,900,951

21 Electrolytic Cleaning 2,405 83,645,332

21R. Electrolytic Cleaning Rinse 2,771 3,346,961,012

22 Electroplating With Chromium 557 30,135,241

22R. Electroplating With Chromium

Rinse

825 1,543,347,451

23 Electroplating With Cyanide 731 87,597,962

23R. Electroplating With Cyanide Rinse 3,185 856,518,170

24 Electroplating Without Chromium

or Cyanide

1,866 54,401,114

24R. Electroplating Without Chromium

or Cyanide Rinse

4,258 3,791,840,777

25 Electropolishing 255 4,485,954

25R. Electropolishing Rinse 253 312,554,885

26 Floor Cleaning 33,326 3,559,210,563

26R. Floor Cleaning Rinse 1,618 46,759,620

27 Grinding 2,193 202,036,389

27R. Grinding Rinse 217 2,831,300,319

28 Heat Treating T 789 196,798,353

28R. Heat Treating Rinse 612 1,804,100,965
4.0 - Industry Description

Survey Unit

Operation

Number Unit Operation Description

Typically

Performed

Dry

Estimated Number of

MP&M Sites

Discharging

Wastewater from Unit

Operation

Total Estimated Industry

Discharge Flow from Unit

Operationb

(gpy)

4-34

29 Impact Deformation T 196 46,225,701

29R. Impact Deformation Rinse 75 8,976,240

30 Machining 3,156 735,611,690

30R. Machining Rinse 297 76,349,552

31 Metal Spraying T 52 186,019

32 Painting - Spray or Brush 1,117 1,349,687,217

32R. Painting - Spray or Brush Rinse 178 1,632,505,169

33 Painting - Immersion 271 237,430,089

33R. Painting - Immersion Rinse 211 165,435,138

34 Plasma Arc Machining T 458 11,893,377

35 Polishing T 540 96,480,600

35R. Polishing Rinse 491 1,687,785,986

36 Pressure Deformation T 287 268,653,304

36R. Pressure Deformation Rinse 92 1,105,233,854

37 Salt Bath Descaling 48 62,902

37R. Salt Bath Descaling Rinse 67 56,171,145

38 Soldering/Brazing T 663 425,693,444

38R. Soldering/Brazing Rinse 1,966 264,719,840

39 Solvent Degreasingc T 106 327,960

39R. Solvent Degreasing Rinse 433 36,576,913

40 Stripping (Paint) 1,089 82,557,395

40R. Stripping (Paint) Rinse 1,573 796,054,566

41 Stripping (Metallic Coating) 1,081 7,415,225

41R. Stripping (Metallic Coating) Rinse 1,447 1,266,477,035

42 Testing 2,351 4,183,822,841

42R. Testing Rinse 591 138,207,480

43 Thermal Cutting 124 104,662,316

43R. Thermal Cutting Rinse 3 28

44 Washing Finished Products 16,862 2,563,540,125

44R. Washing Finished Products Rinse 2,798 703,810,287

45 Welding T 530 1,180,762,371

45R. Welding Rinse 194 61,351,089

46 Wet Air Pollution Control 2,290 3,332,852,389

Source: MP&M Survey Database

a

 MP&M Survey information was used to generate these estimated industry flows and site counts.

b

 These totals do not include sites generating process wastewater that is contract hauled off site or not discharged.

c

 Solvent degreasing operations reported as using process water are included under alkaline treatment (see unit

operation #5).
4.0 - Industry Description

4-35

4.3 Trends in the Industry

For the development of the MP&M rule, EPA collected data from the MP&M

industry for over 10 years, including detailed surveys in 1990 and 1996. Survey data and

industry site visits and sampling have shown numerous changes in the industry between 1990 and

1996. A greater number of facilities now have some type of wastewater treatment system in

place. Survey data show a 30 percent industry increase in treatment systems between 1990 and

1996. Many sites have also begun to implement advanced treatment systems that include

ultrafiltration for increased organics removal and microfiltration units to improve clarification. 

The MP&M survey database indicates that (in 1990) 260 of the facilities with wastewater

treatment in place are currently using membrane filtration. By 1996, that number increased to

700. In addition, sites are moving toward greater implementation of pollution prevention and

water reduction, including progression to zero discharge when possible. Fifty-three percent

currently have in-process pollution prevention or water use reduction practices in place, and over

27 percent of discharging sites report having wet unit operations with zero discharge. 

Improvements in treatment controls are allowing for more automated process controls. This

leads to more consistent wastewater treatment. Advances in wastewater treatment chemicals are

also improving treatment efficiencies. 

4.4 References

1. Cubberly, William H. (ed.). Tool and Manufacturing Engineers Handbook, Desk

Edition, Society of Manufacturing Engineers, Dearborne, MI, 1989. 

2. Detrisac, M. Arthur. "Treatable Cleaners," Metal Finishing. September 1991. 

3. U.S. Environmental Protection Agency. Development Document for Effluent

Limitations Guidelines and Standards for the Metal Finishing Point Source

Category. EPA 440/1-83/091, June 1983. 

4. Mohler, J.B. "Alkaline Cleaning for Electroplating," Metal Finishing. September

1984. 

5. Wood, William G. (Coordinator). The New Metals Handbook, Vol. 5. Surface

Cleaning, Finishing, and Coating. American Society for Metals, May 1990.

6. Lowenheim, Frederick A. Electroplating Fundamentals of Surface Finishing,

McGraw-Hill Book Company, New York, NY, 1978.

7. Murphy, Michael (ed.). Metal Finishing Guidebook and Directory Issue '93,

Metal Finishing. January 1993.
5.0 - Wastewater Characteristics

5-1

5.0 WASTEWATER CHARACTERISTICS

This section summarizes the characteristics of wastewater generated from MP&M

unit operations and raw wastewater entering wastewater treatment systems at MP&M facilities. 

EPA classified wastewater generated from MP&M unit operations into the following types based

on composition and treatment requirements:

C Hexavalent chromium-bearing wastewater;

C Cyanide-bearing wastewater;

C Oil- and organic pollutant-bearing wastewater;

C Chelated metal-bearing wastewater; and

C General metal-bearing wastewater.

Sections 5.1 through 5.5 summarize the unit operations generating each type of

wastewater and the analytical data obtained from sampled MP&M unit operations and wastewater

treatment influent streams. For each pollutant analyzed, EPA lists the number of samples analyzed,

the number of times EPA detected the pollutant, and the minimum, maximum, mean, and median

detected concentrations. EPA obtained analytical data for unit operations and wastewater

treatment systems from the MP&M sampling program. EPA obtained additional analytical data

from sampling conducted by sanitation districts and MP&M industry trade associations. Sections

3.1, 3.4, and 3.5 describe the MP&M sampling program and sampling episodes conducted by

sanitation districts and MP&M industry trade associations. All data presented in this section have

undergone complete analytical QA/QC. 

During the MP&M sampling program, EPA collected 444 wastewater samples

representing 50 distinct unit operations and rinses. These samples, which characterize unit

operations that comprise approximately 90 percent of the total MP&M process wastewater

discharge flow, are discussed in this section. The MP&M surveys identified an additional 20 unit

operations and 24 rinses, accounting for approximately 10 percent of MP&M process wastewater

discharge flow. EPA transferred data to these operations and rinses from the sampling data, based

on process characteristics, as discussed in Section 12.1.2. 

Unit operation-specific analytical data for the operations sampled during the

MP&M sampling program are contained in the administrative record for this rulemaking.

5.1 Hexavalent Chromium-Bearing Wastewater

Hexavalent chromium-bearing wastewater contains elevated concentrations of

hexavalent chromium along with other metals such as aluminum or iron. The wastewater is

generally acidic. Sections 5.1.1 and 5.1.2 discuss hexavalent chromium-bearing wastewater

generated from MP&M unit operations and as influent to chromium-reduction wastewater

treatment units, respectively. 
5.0 - Wastewater Characteristics

5-2

5.1.1 Unit Operations Generating Hexavalent Chromium-Bearing Wastewater

Table 5-1 summarizes the unit operations and associated rinses that generate

hexavalent chromium-bearing wastewater and the number of samples collected of each.

Table 5-1 

Number of Process and Rinse Samples for Unit Operations That Generate

Hexavalent Chromium-Bearing Wastewater

Unit Operation

No. of Process

Samples

No. of Rinse

Samples

 Acid Treatment with Chromium 1 3

 Anodizing with Chromium 3 7

 Chromate Conversion Coating 15 21

 Electroplating with Chromium 4 14

 Wet Air Pollution Control for Chromium-Bearing Operations 6 NA

Source: MP&M surveys and MP&M site visits.

NA - Not applicable. No associated rinse.

Hexavalent chromium is present in wastewater as a component of the process bath

(e.g., chromic acid anodizing, chromate conversion coating, chromium electroplating). MP&M

facilities install wet air pollution control devices to control air emissions of the chromium process

bath constituents. Total and hexavalent chromium concentrations in process baths average 24,022

mg/L and 10 mg/L, respectively. In the associated rinses, the maximum concentration for total and

hexavalent chromium from EPA’s sampling was 17,300 mg/L and 21.2 mg/L, respectively. 

Table 5-2 summarizes the MP&M analytical data for total and hexavalent chromium in wastewater

from unit operations and associated rinses that generate total and hexavalent chromium-bearing

wastewater. Based on the process chemistry of the unit operations (e.g., chromium is present in

the hexavalent form in a chromic acid solution), the Agency believes that some chromium present

in this wastewater is in the hexavalent form. For the purposes of estimating compliance costs, the

Agency assumed that all chromium in this wastewater is in the hexavalent form. EPA made this

assumption to provide a conservative assessment of the costs associated with chromium reduction

treatment. (See Section 11 for a discussion on EPA’s Design and Cost Model).
5.0 - Wastewater Characteristics

5-3

Table 5-2

Summary of Analytical Data for Chromium From Unit Operations and Rinses

Generating Chromium-Bearing Wastewater

Source of

Pollutant

Chromium

Form

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

Unit

Operations

Total 29 29 0.045 139,000 24,022 2,410

Hexavalent 2 1 10 10 10 10

Rinses

Total 45 45 0.22 17,300 1,229 19.3

Hexavalent 6 6 2.1 21.2 10.3 8

Source: MP&M sampling program.

5.1.2 Chromium-Bearing Raw Wastewater Characteristics

Typically, MP&M facilities segregate hexavalent chromium-bearing wastewater

generated from the unit operations listed in Table 5-1 and treat it in a chromium reduction unit

before commingling with other process wastewater for further treatment. Section 8.2.1 describes

chromium reduction technologies used in the MP&M industry. This segregated wastestream

requires preliminary treatment to reduce hexavalent chromium to trivalent chromium since

hexavalent chromium is not effectively treated in chemical precipitation systems. Table 5-3

summarizes the analytical data for hexavalent chromium and total chromium in the raw influent to

chromium reduction units. (See Section 10.0 for a discussion on achievable effluent

concentrations of chromium following chromium reduction and chemical precipitation).

Table 5-3

Summary of Analytical Data for Chromium in Chromium-Bearing Raw

Wastewater at Influent to Hexavalent Chromium Treatment 

Form of Chromium

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Total Chromium 51 51 2.41 432 57.8 19.5

 Hexavalent Chromium 21 18 0.027 20 6.70 4.0

Source: MP&M sampling program.
5.0 - Wastewater Characteristics

5-4

5.2 Cyanide-Bearing Wastewater

Cyanide-bearing wastewater contains elevated concentrations of cyanide along

with other metals such as copper, cadmium, or zinc. High concentrations of cyanide are typically

found in electroplating baths. Cyanide may be analyzed as total cyanide (i.e., all forms included),

amenable cyanide (i.e., cyanide present in forms amenable to treatment using alkaline

chlorination), or weak-acid-dissociable cyanide (i.e., cyanide that dissociates in a weak acid). 

For the purposes of sizing and costing alkaline chlorination systems, EPA made the conservative

assumption that all detected total cyanide was present in a form amenable to alkaline chlorination. 

Sections 5.2.1 and 5.2.2 discuss cyanide-bearing wastewater generated from MP&M unit

operations and as influent to cyanide treatment units, respectively. 

5.2.1 Unit Operations Generating Cyanide-Bearing Wastewater

Table 5-4 summarizes the unit operations and associated rinses that generate

cyanide-bearing wastewater and the number of samples collected of each.

Table 5-4

Number of Process and Rinse Samples for Unit Operations

That Generate Cyanide-Bearing Wastewater

Unit Operation 

No. of Process

Samples No. of Rinse Samples

Alkaline Treatment with Cyanide 2 4

Electroplating with Cyanide 8

a

23

Wet Air Pollution Control for Cyanide-Bearing Operations 3 NA

Source: MP&M surveys and MP&M site visits.

NA - Not applicable. No associated rinse.

a

 Does not include one sample from a gold-cyanide electroplating bath that was only analyzed for metals.

Cyanide is present as a component of electroplating and cleaning baths and in wet

air pollution control wastewater for cyanide-bearing unit operations. Table 5-5 summarizes the

analytical data for total and amenable cyanide collected during the MP&M sampling program from

individual unit operations and their associated rinses that generate cyanide-bearing wastewater. 

Cyanide electroplating baths and rinses also contain several metal pollutants (typically cadmium,

copper, or silver) depending on the type of metal being electroplated.
5.0 - Wastewater Characteristics

5-5

Table 5-5

Summary of Analytical Data for Cyanide from Unit Operations and Rinses

Generating Cyanide-Bearing Wastewater

Source of

Pollutant

Cyanide

Form

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

Unit

Operations

Total 13 13 0.12 100,000 18,964 9,370

Amenable 0 NA NA NA NA NA

Rinses

Total 24 24 0.054 51,000 5,663 12

Amenable 1 1 0.34 0.34 0.34 0.34

Source: MP&M sampling program.

NA - Not applicable. No samples were analyzed for amenable cyanide.

5.2.2 Cyanide-Bearing Raw Wastewater Characteristics 

Typically, MP&M facilities segregate cyanide-bearing wastewater generated from

the unit operations listed in Table 5-4 and treat it in a cyanide destruction unit before commingling

with other process wastewater for further treatment. This preliminary treatment prevents cyanide

complexes from forming in the commingled wastewater. These complexes decrease the

effectiveness of chemical precipitation. Section 8.2.3 discusses cyanide treatment technologies. 

Table 5-6 summarizes the analytical data for cyanide in the influent to cyanide treatment units. 

(See Section 10.0 for a discussion of achievable effluent concentrations of cyanide following

cyanide destruction.)

Table 5-6

Summary of Analytical Data for Cyanide in Cyanide-Bearing Raw

Wastewater at Influent to Cyanide Treatment

Source of

Pollutant

No. of Samples

Analyzed No. of Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Total Cyanide 91 88 0.024 1,110 45.4 3.89

 Amenable Cyanide 65 59 0.01 394 35.8 2.21

Source: MP&M sampling program.
5.0 - Wastewater Characteristics

5-6

5.3 Oil-Bearing and Organic Pollutant-Bearing Wastewater

Oil-bearing wastewater contains elevated concentrations of oil. This wastewater

may need additional treatment for the removal of toxic organics. Oil-bearing wastewater is

classified as either free oils or oil/water emulsions. Sections 5.3.1 and 5.3.2 discuss wastewater

bearing oil and organic pollutants generated from MP&M unit operations and as influent to oily

wastewater treatment units, respectively.

5.3.1 Unit Operations Generating Oil-Bearing and/or Organic Pollutant-Bearing

Wastewater

Table 5-7 summarizes the unit operations and associated rinses that generate

oil-bearing wastewater and the number of samples collected of each.
5.0 - Wastewater Characteristics

5-7

Table 5-7

Number of Process and Rinse Samples For Unit Operations That Generate

Oil-Bearing and/or Organic Pollutant-Bearing Wastewater

Unit Operation No. of Process Samples No. of Rinse Samples

 Alkaline Cleaning for Oil Removal 30 30

 Aqueous Degreasing 12 6

 Barrel Finishing 10 0

 Bilge Water 1 0

 Corrosion Preventive Coating 5 3

 Dry Dock 4 0

 Electrical Discharge Machining 1 0

 Electrolytic Cleaning 7 14

 Floor Cleaning 6 0

 Grinding 5 0

 Heat Treating 3 7

 Impact Deformation 1 0

 Machining 16 0

 Painting - Spray or Brush 6 0

 Painting - Immersion 1 2

 Steam Cleaning 8 0

 Solder Flux Cleaning 3 0

 Solder Fusing 0 3

 Testing 7 2

 Thermal Cutting 2 0

 Washing Finished Products 4 3

 Source: MP&M surveys and MP&M site visits.

Tables 5-8 and 5-9 summarize the analytical data collected during the MP&M

sampling program from individual unit operations that generate oil-bearing wastewater and their

associated rinses, respectively. MP&M facilities typically use oil/water emulsions as coolants

and lubricants in machining, grinding, and deformation operations. Oil is also present as a

contaminant in wastewater from cleaning operations. The maximum concentration of oil and

grease in wastewater sampled by EPA from these unit operations was 36,850 mg/L (from an

alkaline cleaning bath), while the maximum concentration of oil and grease in the wastewater from

the rinses associated with these unit operations was 9,195 mg/L. 

As shown in Tables 5-8 and 5-9, the oil-bearing wastewater also contains

numerous organic pollutants. These pollutants are either components of the oil/water emulsions or

contaminants in the cleaning solutions. The maximum organic pollutant concentration found in
5.0 - Wastewater Characteristics

5-8

EPA samples was 19,813 mg/L of benzoic acid from a testing unit operation. The maximum

organic pollutant concentration in the rinses was 160 mg/L for n-tetradecane from a testing rinse

operation. Tables 5-8 and 5-9 show that these unit operations also contain conventional, nonconventional, and metal pollutants.

A major source of organic pollutants at MP&M facilities is solvent degreasing. 

Solvent degreasing operations use organic solvents such as trichloroethylene or mineral spirits,

and do not use water. Therefore, for the purposes of the MP&M effluent guidelines, EPA did not

consider waste from solvent degreasing a regulated wastewater. In rare situations, EPA identified

rinses following solvent degreasing. EPA classified these rinses as MP&M wastewater. The

Agency classified cleaning operations that use an emulsion of water and solvents as emulsion

cleaning (a subset of alkaline cleaning) and considered these waste streams as MP&M regulated

wastewater.

Table 5-8

Analytical Data for Unit Operations Generating Oil-Bearing and/or

Organic-Bearing Wastewater

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,1,1-Trichloroethane 72 1 0.011 0.011 0.011 0.011

 1,1,2,2-Tetrachloroethane 70 1 0.011 0.011 0.011 0.011

 1,1,2-Trichloroethane 72 1 0.012 0.012 0.012 0.012

 1,2-Dichlorobenzene 72 1 0.638 0.638 0.638 0.638

 2,4,6-Trichlorophenol 72 1 0.014 0.014 0.014 0.014

 2,4-Dimethylphenol 71 4 0.016 0.064 0.051 0.062

 4-Chloro-3-Methylphenol 72 11 0.011 91.1 18.2 0.587

 4-Nitrophenol 70 1 0.424 0.424 0.424 0.424

 Acrolein 72 1 0.161 0.161 0.161 0.161

 Acrylonitrile 72 1 0.061 0.061 0.061 0.061

 Anthracene 72 1 0.193 0.193 0.193 0.193

 Benzene 72 2 0.014 0.044 0.03 0.029

 Bis(2-ethylhexyl) Phthalate 72 21 0.012 143 7.44 0.085

 Bromodichloromethane 72 3 0.012 0.072 0.032 0.012

 Butyl Benzyl Phthalate 72 1 0.066 0.066 0.066 0.066

 Chlorobenzene 72 2 0.028 0.058 0.043 0.043

 Chloroethane 72 1 8.34 8.34 8.34 8.34

 Chloroform 72 5 0.010 0.019 0.014 0.013
Table 5-8 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-9

Priority Organic Pollutants (continued)

 Chloromethane 72 1 0.069 0.069 0.069 0.069

 Di-n-butyl Phthalate 72 4 0.012 0.070 0.038 0.035

 Di-n-octyl Phthalate 72 1 0.020 0.020 0.020 0.020

 Dibromochloromethane 72 2 0.010 0.011 0.011 0.011

 Dimethyl Phthalate 72 2 0.021 2.000 1.010 1.010

 Ethylbenzene 72 5 0.028 2.91 0.773 0.191

 Fluoranthene 72 4 0.029 0.243 0.132 0.129

 Fluorene 72 2 0.010 0.021 0.015 0.015

 Methylene Chloride 72 3 0.028 6.76 2.27 0.030

 n-nitrosodiphenylamine 72 1 0.025 0.025 0.025 0.025

 Naphthalene 72 5 0.019 1.839 0.413 0.081

 Phenanthrene 72 4 0.101 5.50 1.47 0.143

 Phenol 72 21 0.012 8.84 1.05 0.05

 Tetrachloroethene 72 2 0.015 0.02 0.02 0.018

 Toluene 72 7 0.029 0.653 0.162 0.103

 Trichloroethene 72 8 0.019 0.042 0.024 0.021

 Priority Metal Pollutants

 Antimony 131 40 0.004 0.804 0.124 0.040

 Arsenic 132 57 0.001 1.65 0.100 0.021

 Beryllium 132 21 0.000 0.025 0.004 0.002

 Cadmium 132 71 0.002 12.1 1.12 0.097

 Chromium 132 104 0.007 255 5.43 0.136

 Copper 132 123 0.006 190 6.58 0.660

 Cyanide 10 7 0.004 0.232 0.078 0.059

 Lead 132 78 0.006 1,450 29.9 0.538

 Mercury 132 28 0.000 0.017 0.001 0.000

 Nickel 132 94 0.013 80.9 2.24 0.164

 Selenium 131 37 0.001 1.57 0.099 0.021

 Silver 132 39 0.003 2.12 0.175 0.016

 Thallium 131 20 0.001 0.113 0.021 0.018

 Zinc 132 121 0.008 1,160 37.2 1.39

 Conventional Pollutants

 BOD 5-day (Carbonaceous) 64 56 3 64,900 3,207 645

 Oil And Grease 63 59 2.4 570,000 28,592 790
Table 5-8 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-10

Conventional Pollutants (continued)

 Oil and Grease (as HEM) 66 50 7.75 36,850 2,351 211

 pH 69 69 3.44 13.9 8.85 8.24

 Total Suspended Solids 132 127 4 43,580 1,940 185

 Nonconventional Organic Pollutants

 1,4-Dioxane 72 2 0.077 1.00 0.539 0.539

 1-Methylfluorene 72 3 0.014 2.60 0.912 0.123

 1-Methylphenanthrene 72 3 0.122 5.65 1.97 0.147

 2-(Methylthio)Benzothiazole 72 1 0.028 0.028 0.028 0.028

 2-Butanone 72 13 0.057 38.3 3.70 0.101

 2-Hexanone 72 3 0.124 0.505 0.263 0.161

 2-Isopropylnaphthalene 72 1 7.34 7.34 7.34 7.34

 2-Methylnaphthalene 72 9 0.011 3.14 0.511 0.236

 2-Picoline 72 1 0.072 0.072 0.072 0.072

 2-Propanone 72 40 0.060 11.9 0.966 0.220

 3,6-Dimethylphenanthrene 72 1 8.50 8.5 8.50 8.50

 4-Methyl-2-Pentanone 72 10 0.124 159 22.6 0.457

 Acetophenone 72 1 0.566 0.566 0.566 0.566

 Alpha-terpineol 71 12 0.012 14.1 2.69 1.780

 Benzoic Acid 72 13 0.071 19,813 1,525 0.287

 Benzyl Alcohol 72 3 0.023 0.208 0.108 0.094

 Biphenyl 72 2 0.014 0.038 0.026 0.026

 Cis-1,3-dichloropropene 72 1 0.012 0.012 0.012 0.012

 Diphenyl Ether 72 1 0.013 0.013 0.013 0.013

 Diphenylamine 72 2 0.024 0.026 0.025 0.025

 Hexanoic Acid 72 24 0.019 1,490 66.3 0.903

 Isobutyl Alcohol 72 3 0.012 1.31 0.446 0.018

 m+p xylene 47 2 0.013 0.352 0.183 0.183

 m-xylene 25 3 0.153 5.06 2.45 2.13

 n,n-dimethylformamide 72 5 0.028 0.665 0.265 0.036

 n-decane 72 9 0.017 1.33 0.462 0.132

 n-docosane 72 23 0.013 141 7.98 0.164

 n-dodecane 72 24 0.011 36.8 3.60 0.419

 n-eicosane 72 29 0.012 14.1 1.40 0.190

 n-hexacosane 72 20 0.011 109 7.43 0.099
Table 5-8 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-11

Nonconventional Organic Pollutants (continued)

 n-hexadecane 72 28 0.015 95.3 6.64 0.444

 n-octacosane 72 8 0.035 61.1 10.4 0.524

 n-octadecane 72 28 0.01 264 13.1 0.198

 n-tetracosane 72 17 0.011 116 9.34 0.267

 n-tetradecane 72 29 0.011 48.5 6.48 0.674

 n-triacontane 72 12 0.012 31.9 3.78 0.433

 o+p xylene 25 3 0.063 2.01 1.19 1.48

 o-xylene 47 6 0.010 0.201 0.044 0.013

 p-cresol 72 6 0.010 4.31 0.74 0.029

 p-cymene 72 2 0.021 0.1 0.04 0.036

 Styrene 72 1 1.184 1.18 1.18 1.18

 Toluene, 2,4-diamino- 72 1 101 101 101 101

 Trichlorofluoromethane 72 1 0.106 0.106 0.106 0.106

 Tripropyleneglycol Methyl Ether 72 5 1.93 5,254 1,462 413

 Nonconventional Metal Pollutants

 Aluminum 132 113 0.039 414 22.3 1.83

 Barium 132 114 0.001 31.4 1.88 0.108

 Bismuth 1 1 0.058 0.058 0.058 0.058

 Boron 132 113 0.059 2,290 87.1 1.27

 Calcium 132 128 0.274 981 63.9 38.75

 Cobalt 132 54 0.005 1.26 0.131 0.037

 Gold 6 2 0.081 1.66 0.871 0.871

 Iridium 1 1 0.596 0.596 0.596 0.596

 Iron 132 126 0.016 2,790 50.2 6.10

 Lutetium 1 1 0.007 0.007 0.007 0.007

 Magnesium 132 121 0.088 213 24.6 10.5

 Manganese 132 122 0.002 24.1 1.36 0.271

 Molybdenum 132 87 0.003 774 11.7 0.095

 Neodymium 1 1 0.020 0.020 0.020 0.020

 Niobium 1 1 0.104 0.104 0.104 0.104

 Potassium 1 1 0.574 0.574 0.574 0.574

 Silicon 1 1 19.9 19.9 19.9 19.9

 Sodium 132 128 1.61 68,700 3,847 299

 Strontium 1 1 8.02 8.0186 8.02 8.02
Table 5-8 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-12

 Nonconventional Metal Pollutants (continued)

 Sulfur 1 1 0.636 0.636 0.636 0.636

 Tantalum 1 1 0.134 0.134 0.134 0.134

 Tin 132 61 0.004 852 15.7 0.101

 Titanium 132 86 0.001 30.0 0.658 0.045

 Tungsten 1 1 0.175 0.175 0.175 0.175

 Vanadium 132 51 0.005 0.482 0.072 0.023

 Ytterbium 1 1 0.006 0.006 0.006 0.01

 Yttrium 132 37 0.001 0.900 0.045 0.008

 Other Nonconventional Pollutants

 Acidity 51 17 1.00 250,000 14,818 9.00

 Ammonia As Nitrogen 43 36 0.160 1,600 71.8 2.54

 Chemical Oxygen Demand (COD) 107 103 22.4 366,000 27,871 4,930

 Chloride 52 49 2.00 48,000 1,604 180

 Fluoride 59 56 0.130 35.0 3.92 1.35

 Hexavalent Chromium 63 13 0.016 1.70 0.207 0.055

 Sulfate 66 54 1.50 46,000 2,483 272.23

 Total Alkalinity 53 52 51.5 92,000 13,989 2,000

 Total Dissolved Solids 128 128 33.5 411,420 23,538 4,500

 Total Kjeldahl Nitrogen 44 41 0.200 580 68.9 37.0

 Total Organic Carbon (TOC) 67 63 4.26 118,000 7,184 471

 Total Petroleum Hydrocarbons (As SGT- 

 HEM) 65 42 6.00 6,230 481 52.5

 Total Phosphorus 35 34 0.065 7,170 291 18.85

 Total Recoverable Phenolics 105 87 0.005 33.8 1.67 0.197

 Total Sulfide 9 5 1.00 11.0 4.40 2.00

Source: MP&M sampling program.
5.0 - Wastewater Characteristics

5-13

Table 5-9

Analytical Data for Rinses Generating Oil-Bearing and/or

Organic-Bearing Wastewater

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,1,1-Trichloroethane 40 1 0.023 0.023 0.023 0.023

 1,1-Dichloroethane 40 1 0.039 0.039 0.039 0.039

 2,6-Dinitrotoluene 40 1 0.616 0.616 0.616 0.616

 4-Chloro-3-Methylphenol 40 2 0.023 0.050 0.037 0.037

 Bis(2-Ethylhexyl) Phthalate 40 10 0.011 1.15 0.336 0.187

 Bromodichloromethane 40 4 0.010 0.014 0.011 0.010

 Chloroform 40 11 0.010 0.035 0.017 0.012

 Di-n-butyl Phthalate 40 4 0.014 0.019 0.017 0.017

 Ethylbenzene 40 3 0.021 0.039 0.029 0.028

 Methylene Chloride 40 1 0.016 0.016 0.016 0.016

 n-nitrosodi-n-propylamine 40 1 0.132 0.132 0.132 0.132

 Naphthalene 40 3 0.021 2.01 0.892 0.643

 Phenanthrene 40 1 0.527 0.527 0.527 0.527

 Phenol 40 5 0.011 8.28 1.67 0.024

 Toluene 40 2 0.011 0.045 0.028 0.028

 Trichloroethene 40 6 0.011 0.022 0.02 0.02

 Priority Metal Pollutants

 Antimony 69 18 0.0028 0.256 0.047 0.032

 Arsenic 70 15 0.0013 0.303 0.037 0.008

 Beryllium 70 5 0.0011 0.005 0.002 0.002

 Cadmium 70 22 0.002 11.9 0.618 0.052

 Chromium 70 41 0.009 104 2.88 0.159

 Copper 70 59 0.008 14.7 0.958 0.144

 Cyanide 2 2 0.010 1.45 0.730 0.730

 Lead 70 23 0.031 6.89 1.17 0.495

 Mercury 70 11 0.00005 0.001 0.0003 0.0002

 Nickel 70 38 0.008 10.3 0.744 0.105

 Selenium 69 5 0.001 0.232 0.082 0.031

 Silver 70 16 0.004 0.081 0.022 0.010

 Thallium 69 5 0.002 0.036 0.014 0.006

 Zinc 70 53 0.009 46.7 2.28 0.134
Table 5-9 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-14

 Conventional Pollutants

 BOD 5-day (Carbonaceous) 38 34 4.00 12,900 1,209 179

 Oil And Grease 23 16 1.35 2,700 440 41.5

 Oil And Grease (As HEM) 38 27 5.00 9,195 472 42

 pH 38 38 2.40 13.2 9.24 9.31

 Total Suspended Solids 70 56 4.00 2,560 178 64.2

 Nonconventional Organic Pollutants

 1,4-Dioxane 40 1 0.196 0.196 0.196 0.196

 1-Methylfluorene 40 1 0.129 0.129 0.129 0.129

 1-Methylphenanthrene 40 1 1.02 1.02 1.02 1.02

 2-Butanone 40 3 0.074 0.126 0.093 0.078

 2-Isopropylnaphthalene 40 1 1.57 1.57 1.57 1.57

 2-Methylnaphthalene 40 1 1.10 1.10 1.10 1.10

 2-Propanone 40 14 0.055 3.10 0.444 0.197

 3,6-Dimethylphenanthrene 40 1 0.811 0.811 0.811 0.811

 4-Methyl-2-Pentanone 40 2 0.190 17.4 8.80 8.80

 Alpha-Terpineol 39 2 65.3 67.3 66.3 66.3

 Benzoic Acid 40 6 0.108 6.61 1.76 1.05

 Benzyl Alcohol 40 2 2.73 24.8 13.8 13.8

 Hexanoic Acid 40 15 0.015 28.4 2.40 0.536

 m+p xylene 25 1 0.104 0.10 0.104 0.104

 m-xylene 15 2 0.036 0.08 0.056 0.056

 n,n-dimethylformamide 40 1 0.011 0.011 0.011 0.011

 n-decane 40 1 5.01 5.01 5.01 5.01

 n-docosane 40 7 0.018 6.47 1.07 0.030

 n-dodecane 40 6 1.77 53.3 15.3 7.24

 n-eicosane 40 13 0.011 2.4 0.490 0.172

 n-hexacosane 40 8 0.011 1.46 0.443 0.250

 n-hexadecane 40 10 0.011 52.7 11.0 0.755

 n-octacosane 40 4 0.041 1.37 0.624 0.540

 n-octadecane 40 10 0.018 4.03 0.952 0.159

 n-tetracosane 40 10 0.012 17.0 1.87 0.094

 n-tetradecane 40 6 0.221 160 53.3 3.12

 n-triacontane 40 4 0.030 0.477 0.217 0.180

 o-cresoL 40 1 0.012 0.012 0.012 0.012

 o-xylene 25 1 0.056 0.056 0.056 0.056

 p-cymene 40 1 0.190 0.190 0.190 0.190

 Phenothiazine 40 1 0.582 0.582 0.582 0.582
Table 5-9 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-15

 Nonconventional Organic Pollutants (continued)

 Trichlorofluoromethane 40 1 0.036 0.036 0.036 0.036

 Tripropyleneglycol Methyl Ether 40 3 0.413 4.18 2.43 2.71

 Nonconventional Metal Pollutants

 Aluminum 70 36 0.031 19.7 2.72 0.823

 Barium 70 58 0.001 1.61 0.181 0.044

 Boron 70 48 0.019 838 28.0 0.195

 Calcium 70 66 0.940 175 34.8 22.8

 Cobalt 70 11 0.007 0.546 0.102 0.024

 Gold 4 2 0.056 0.086 0.071 0.071

 Iron 70 53 0.034 453 18.1 0.275

 Magnesium 70 65 0.137 37.3 9.69 8.00

 Manganese 70 51 0.002 8.63 0.394 0.040

 Molybdenum 70 36 0.006 187 5.34 0.023

 Palladium 3 1 0.054 0.054 0.054 0.054

 Sodium 70 68 1.63 19,100 603 87.2

 Tin 70 25 0.006 10.9 1.18 0.056

 Titanium 70 23 0.002 1.53 0.259 0.040

 Vanadium 70 19 0.003 0.182 0.030 0.023

 Yttrium 70 7 0.002 0.020 0.008 0.007

 Other Nonconventional Pollutants

 Acidity 19 8 2.00 120 26.5 16.0

 Ammonia as Nitrogen 13 8 0.02 0.920 0.439 0.43

 Chemical Oxygen Demand (COD) 47 44 5.20 32,700 2,561 347

 Chloride 19 19 3.00 64,500 3,435 22.0

 Fluoride 19 19 0.11 135 7.80 0.710

 Hexavalent Chromium 38 12 0.011 0.069 0.025 0.022

 Sulfate 26 22 6.60 780 122 29.0

 Total Alkalinity 19 18 24 3,800 518 195

 Total Dissolved Solids 70 69 26 120,000 3,563 708

 Total Kjeldahl Nitrogen 10 7 0.36 149 23 1.68

 Total Organic Carbon (TOC) 38 35 2.66 10,100 867 120

 Total Petroleum Hydrocarbons (As SGT- 37 19 5.00 7,367 455 28.0

 Total Phosphorus 7 7 0.06 11.0 4.1 2.16

 Total Recoverable Phenolics 48 37 0.0056 2.78 0.233 0.070

 Total Sulfide 1 1 12.0 12.0 12.0 12.0

Source: MP&M sampling program.
5.0 - Wastewater Characteristics

5-16

5.3.2 Oil-Bearing and Organic Pollutant-Bearing Raw Wastewater Characteristics

Wastewater containing oil and organic pollutants generated from the unit operations

listed in Table 5-7 generally requires treatment to separate oil from the wastewater. If the oils are

free or floating, then the oil and water can be separated using physical means such as oil skimming

or ultrafiltration. If the oil is emulsified, techniques such as chemical emulsion breaking may be

required before physical separation. Oil/water separation technologies also remove organic

pollutants that are more soluble in oil than in water. Sections 8.2.5 and 8.3.2 discuss oil-water

separation technologies used in the MP&M industry. Table 5-10 summarizes the characteristics of

raw wastewater influent to oily wastewater treatment systems. (See Section 10.0 for a discussion

on achievable effluent concentrations of oil and grease and organics following oil/water

separation and chemical precipitation.) 

Table 5-10

Analytical Data for Oil-Bearing and Organic Pollutant-Bearing Raw

Wastewater Streams at Influent to Oil/Water Separation

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,1,1-Trichloroethane 82 5 0.006 0.022 0.013 0.013

 1,2-Dichlorobenzene 82 1 0.638 0.638 0.638 0.638

 2,4-Dimethylphenol 81 2 0.017 0.270 0.144 0.144

 2-Nitrophenol 82 1 0.025 0.025 0.025 0.025

 4-Chloro-3-Methylphenol 82 18 0.247 3,834 706 101

 Acenaphthene 82 5 0.006 1.82 0.396 0.025

 Acrolein 77 1 0.168 0.168 0.168 0.168

 Anthracene 82 1 0.007 0.007 0.007 0.007

 Benzene 82 2 0.007 0.012 0.010 0.010

 Bis(2-Ethylhexyl) Phthalate 81 62 0.007 216 6.66 0.157

 Butyl Benzyl Phthalate 81 7 0.024 2.73 0.440 0.065

 Carbon Tetrachloride

 (Tetrachloromethane) 82 3 0.011 0.046 0.025 0.017

 Chloroform 82 6 0.010 0.038 0.019 0.016

 Chloromethane 82 1 0.736 0.736 0.736 0.736

 Di-n-butyl Phthalate 81 8 0.011 0.193 0.087 0.080

 Di-n-octyl Phthalate 82 10 0.010 19.7 2.37 0.332

 Ethylbenzene 82 18 0.010 0.260 0.077 0.036
Table 5-10 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-17

 Priority Organic Pollutants (continued)

 Fluorene 82 6 0.010 9.93 1.71 0.067

 n-Nitrosodiphenylamine 82 5 0.025 2.59 1.34 1.69

 Naphthalene 82 15 0.011 8.91 1.04 0.046

 Phenanthrene 82 17 0.012 5.30 0.486 0.033

 Phenol 81 31 0.018 27.1 1.31 0.138

 Pyrene 81 2 0.031 1.01 0.521 0.521

 Tetrachloroethene 82 1 0.006 0.006 0.006 0.006

 Toluene 82 21 0.006 1.35 0.199 0.033

 Priority Metal Pollutants

 Antimony 86 33 0.002 0.105 0.022 0.017

 Arsenic 86 38 0.002 0.534 0.036 0.006

 Beryllium 86 20 0.0002 0.187 0.036 0.002

 Cadmium 86 62 0.002 12.1 0.805 0.030

 Chromium 86 74 0.003 15.9 0.726 0.071

 Copper 86 86 0.027 232 23.0 0.408

 Lead 86 70 0.006 210 17.1 0.239

 Mercury 86 26 0.0001 0.003 0.0009 0.0004

 Nickel 86 71 0.012 18.4 0.913 0.155

 Selenium 86 13 0.001 0.124 0.028 0.011

 Silver 86 18 0.004 2.8 0.272 0.022

 Thallium 86 6 0.001 0.068 0.012 0.001

 Zinc 86 84 0.145 664 26.0 1.66

 Conventional Pollutants

 BOD 5-Day (Carbonaceous) 75 69 4 21,300 2,745 675

 Oil And Grease 86 84 8.33 261,500 12,149 872

 Total Suspended Solids 86 84 6 100,000 3,712 260

 Nonconventional Organic Pollutants

 1,4-Dioxane 77 2 0.080 0.105 0.093 0.093

 1-Methylfluorene 77 10 0.010 1.72 0.223 0.020

 1-Methylphenanthrene 77 9 0.015 1.23 0.243 0.027

 1-Naphthylamine 77 1 0.034 0.034 0.034 0.034

 2-(Methylthio)Benzothiazole 77 3 0.012 0.023 0.017 0.015

 2-Butanone 77 9 0.130 0.483 0.287 0.256

 2-Hexanone 77 2 0.505 0.512 0.509 0.509
Table 5-10 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-18

Nonconventional Organic Pollutants (continued)

 2-Isopropylnaphthalene 77 2 0.421 3.49 1.96 1.96

 2-Methylnaphthalene 77 17 0.029 13.0 1.17 0.132

 2-Propanone 77 62 0.060 28.8 4.48 0.858

 3,6-Dimethylphenanthrene 77 5 0.013 1.28 0.583 0.371

 4-Methyl-2-Pentanone 77 10 0.073 6.72 0.835 0.153

 Acetophenone 77 3 0.014 0.092 0.051 0.047

 Alpha-Terpineol 77 32 0.011 189 19.9 1.59

 Aniline 77 1 0.014 0.014 0.014 0.014

 Benzoic Acid 77 4 0.108 0.522 0.288 0.261

 Benzyl Alcohol 77 11 0.011 10.8 1.08 0.141

 Biphenyl 77 10 0.014 1.54 0.220 0.054

 Carbazole 77 1 0.035 0.035 0.035 0.035

 Carbon Disulfide 77 5 0.045 0.466 0.312 0.369

 Dibenzofuran 77 1 0.014 0.014 0.014 0.014

 Dibenzothiophene 76 3 0.015 1.293 0.452 0.048

 Diphenylamine 77 5 0.034 1.99 1.24 1.66

 Hexanoic Acid 77 31 0.011 31.9 4.61 0.508

 m+p-Xylene 39 11 0.023 0.457 0.169 0.139

 m-Xylene 38 6 0.018 0.312 0.071 0.024

 n,n-Dimethylformamide 77 2 0.014 0.023 0.019 0.019

 n-Decane 77 32 0.013 27.7 2.94 0.086

 n-Docosane 77 43 0.011 79.7 2.87 0.119

 n-Dodecane 77 47 0.017 207 23.2 0.919

 n-Eicosane 76 52 0.010 109 6.67 0.220

 n-Hexacosane 77 32 0.014 217 9.09 0.169

 n-Hexadecane 77 58 0.012 145 8.60 0.362

 n-Nitrosomorpholine 77 2 0.012 0.135 0.074 0.074

 n-Octacosane 77 8 0.075 70.7 16.1 6.17

 n-Octadecane 77 59 0.011 162 6.43 0.273

 n-Tetracosane 76 32 0.021 56.8 3.32 0.248

 n-Tetradecane 77 61 0.011 243 15.7 0.277

 n-Triacontane 76 10 0.016 25.6 5.60 1.55

 o+p-Xylene 38 6 0.011 0.030 0.021 0.021

 o-Cresol 77 1 0.047 0.047 0.047 0.047
Table 5-10 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-19

Nonconventional Organic Pollutants (continued)

 o-Xylene 39 14 0.012 0.130 0.065 0.071

 p-Cresol 77 10 0.018 1.09 0.297 0.056

p-Cymene 77 10 0.015 14.6 1.54 0.079

 Pentamethylbenzene 77 1 1.24 1.24 1.24 1.24

 Pyridine 77 15 0.014 3.42 1.02 0.063

 Safrole 77 1 0.065 0.065 0.065 0.065

 Tripropyleneglycol Methyl Ether 77 11 0.447 1,550 386 30.1

 Nonconventional Metal Pollutants

 Aluminum 86 76 0.076 134 14.3 3.58

 Barium 86 85 0.019 32 2.06 0.186

 Boron 86 85 0.191 686 37.6 6.39

 Calcium 86 85 1.66 2,200 170 41.3

 Cobalt 86 41 0.008 1.22 0.212 0.102

 Gold 1 1 2.81 2.81 2.81 2.81

 Iron 86 84 0.604 940 52.7 11.0

 Magnesium 86 84 0.180 255 38.3 11.9

 Manganese 86 84 0.031 29 1.90 0.373

 Molybdenum 86 66 0.003 40.3 1.50 0.098

 Sodium 86 85 27.1 2,030 442 210

 Tin 86 55 0.003 85.2 3.22 0.058

 Titanium 86 64 0.003 1.80 0.194 0.079

 Vanadium 86 43 0.004 0.482 0.060 0.025

 Yttrium 86 24 0.001 1.00 0.091 0.013

 Other Nonconventional Pollutants

 Ammonia as Nitrogen 11 11 0.290 160 44.5 24.4

 Chemical Oxygen

 Demand (COD) 85 85 30 213,000 24,961 5,750

 Chloride 7 7 22 450 110 37.0

 Fluoride 12 12 0.500 17 2.94 0.975

 Hexavalent Chromium 71 14 0.010 1.74 0.195 0.021

 Sulfate 35 34 16 176,000 15,585 430

 Total Alkalinity 6 6 180 4,900 1,498 210

 Total Dissolved Solids 82 82 272 88,800 9,930 2,600

 Total Kjeldahl Nitrogen 11 11 0.840 1,500 302 8.86
Table 5-10 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-20

 Other Nonconventional Pollutants (continued)

 Total Organic Carbon (TOC) 70 68 7.66 106,000 7,028 1,230

 Total Petroleum Hydrocarbon 

(As SGT-HEM) 74 68 5.07 25,431 2,213 511

 Total Phosphorus 20 20 0.160 240 38.2 17.0

 Total Recoverable Phenolics 84 81 0.005 1,360 59.3 0.220

 Total Sulfide 23 20 3.00 18.0 7.85 7.00

Source: MP&M sampling program.

5.4 Chelated Metal-Bearing Wastewater

Chelated metal-bearing wastewater contains elevated concentrations of metals,

typically copper or nickel. Sections 5.4.1 and 5.4.2 discuss chelated metal-bearing wastewater

generated from MP&M unit operations and as influent to chelation-breaking wastewater treatment

units, respectively.

5.4.1 Unit Operations Generating Chelated Metal-Bearing Wastewater

Electroless plating operations and rinses are the most common MP&M operations

that generate chelated metal-bearing wastewater. Some cleaning operations also generate chelated

metal-bearing wastewater. MP&M facilities use chelating agents in these unit operations to

prevent metals from precipitating out of solution in the process bath. 

During the MP&M sampling program, EPA collected samples of electroless nickel

plating solutions and rinses that generate chelated metal-bearing wastewater. The maximum

concentration of nickel detected in wastewater from the unit operations was 7,530 mg/L, while the

maximum concentration of nickel in the wastewater from rinses was 378 mg/L. Other metals

typically plated using electroless plating include copper, gold, palladium, and cobalt. EPA

expects the concentrations of the plated metals in these solutions and associated rinses to be

similar to the concentrations measured for nickel during the MP&M sampling program. 

5.4.2 Chelation-Breaking Raw Wastewater Characteristics

Typical chemical precipitation and sedimentation treatment units do not effectively

remove chelated metals; therefore, chelated metal-bearing wastewater typically requires

segregation and preliminary treatment to break down the metal chelates before commingling with

other metal-bearing waste streams for further treatment. If facilities do not segregate these streams

from other metal-bearing waste streams, the chelated metal will not be efficiently removed. EPA

detected copper concentrations ranging from 570 mg/L to 700 mg/L in influent samples from
5.0 - Wastewater Characteristics

5-21

preliminary treatment systems for electroless copper operations. EPA detected nickel at

concentrations ranging from 0.149 mg/L to 480 mg/L in influent samples from preliminary

treatment systems for electroless nickel operations. (See Section 10.0 for a discussion on

achievable effluent concentrations of these chelated metals following chelation breaking/removal

and chemical precipitation.)

Preliminary treatment may consist of chemical reduction using reducing agents such

as sodium borohydride, hydrazine, dithiocarbamate (measured analytically as ziram) or sodium

hydrosulfite; high-pH precipitation using calcium hydroxide or ferrous sulfate; or filtering the

chelated metals out of solution. Section 8.2.4 describes typical metal chelation-bearing

wastewater treatment technologies used in the MP&M industry. 

5.5 General Metal-Bearing Wastewater

All MP&M unit operations can generate metal-bearing wastewater, including those

wastewater streams described in the previous sections. Sections 5.5.1 and 5.5.2 discuss metalbearing wastewater not previously discussed that is generated from MP&M unit operations and

treated in chemical precipitation systems, respectively.

5.5.1 Unit Operations Generating General Metal-Bearing Wastewater

Table 5-11 summarizes the unit operations and associated rinses that generate

general metal-bearing wastewater and the number of samples collected of each.
5.0 - Wastewater Characteristics

5-22

Table 5-11

Number of Process and Rinse Samples From Unit Operations That Generate

General Metal-Bearing Wastewater

Unit Operation No. of Process Samples No. of Rinse Samples

 Abrasive Blasting 3 3

 Abrasive Jet Machining 1 0

 Acid Treatment without Chromium 26 57

 Adhesive Bonding 1 0

 Alkaline Treatment without Cyanide 12 34

 Anodizing without Chromium 4 4

 Carbon Black Deposition 1 0

 Chemical Milling 5 12

 Chemical Conversion Coating without Chromium 19 42

 Electrochemical Machining 1 2

 Electroless Plating 6 15

 Electroplating without Chromium or Cyanide 18 41

 Electropolishing 1 1

 Multiple Unit Operation Rinse 1 0

 Photo Image Developing 5 11

 Photo Resist Applications 1 3

 Plasma Arc Machining 1 0

 Salt Bath Descaling 1 3

 Stripping (paint) 10 16

 Stripping (metallic coating) 8 8

 Welding 0 1

 Wet Air Pollution Control (includes Acid/Alkaline

 and Fumes and Dust)

16 NA

Source: MP&M surveys and MP&M site visits.

NA - Not Applicable. No associated rinse.

Tables 5-12 and 5-13 summarize the analytical data collected during the MP&M

sampling program for wastewater from unit operations and associated rinses, respectively, that

generate general metal-bearing wastewater. As shown in these tables, the priority metal pollutants

most commonly detected in samples of this wastewater were copper, zinc, chromium, nickel, and

lead. Nonconventional metal pollutants frequently detected include iron, magnesium, boron,

barium, manganese, and aluminum. Metal pollutants are typically present in unit operation process

baths that apply or remove metal, such as electroplating or stripping process baths. EPA detected

metal concentrations of up to 383,000 mg/L in unit operation process baths and up to 85,300 mg/L

in unit operation rinses. This wastewater also typically contained oil and grease, total suspended

solids, and low concentrations of organic pollutants.
5.0 - Wastewater Characteristics

5-23

Table 5-12

Analytical Data from Unit Operations Generating

General Metal-Bearing Wastewater

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,2,4-Trichlorobenzene 57 1 0.109 0.109 0.109 0.109

 2,4-Dimethylphenol 54 3 0.049 0.167 0.091 0.056

 2,4-Dinitrophenol 50 4 0.065 335 83.7 0.123

 2,4-Dinitrotoluene 57 1 23.4 23.4 23.4 23.4

 2,6-Dinitrotoluene 57 2 0.605 6.98 3.79 3.79

 2-Nitrophenol 56 4 0.034 2.15 0.574 0.059

 4,6-Dinitro-o-Cresol 53 3 0.037 0.065 0.047 0.039

 4-Nitrophenol 54 4 0.101 14.1 3.63 0.153

 Acrolein 57 1 0.591 0.591 0.591 0.591

 Benzene 57 4 0.015 0.225 0.069 0.019

 Bis(2-Ethylhexyl) Phthalate 57 15 0.012 18.2 2.54 0.326

 Bromodichloromethane 57 2 0.017 0.017 0.017 0.017

 Chlorobenzene 57 4 0.011 1.56 0.402 0.018

 Chloroform 57 6 0.012 0.218 0.050 0.017

 Chloromethane 57 1 0.101 0.101 0.101 0.101

 Di-n-butyl Phthalate 57 1 0.105 0.105 0.105 0.105

 Di-n-octyl Phthalate 57 2 0.639 1.42 1.03 1.03

 Dibromochloromethane 57 2 0.013 0.015 0.014 0.014

 Ethylbenzene 57 3 0.020 0.030 0.024 0.021

 Fluorene 57 1 0.016 0.016 0.016 0.016

 Methylene Chloride 57 4 0.010 0.173 0.062 0.033

 n-Nitrosodi-n-Propylamine 56 1 0.841 0.841 0.841 0.841

 n-Nitrosodimethylamine 57 1 6.67 6.67 6.67 6.67

 Naphthalene 57 3 0.024 0.208 0.103 0.077

 Nitrobenzene 57 1 0.119 0.119 0.119 0.119

 Phenanthrene 57 1 0.037 0.037 0.037 0.037

 Phenol 57 8 0.020 1,044 136 0.538

 Pyrene 57 1 0.016 0.016 0.016 0.016

 Toluene 57 2 0.014 0.047 0.031 0.031

 Trichloroethene 56 8 0.010 2.29 0.310 0.024
5.0 - Wastewater Characteristics

Table 5-12 (Continued)

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-24

 Priority Metal Pollutants

 Antimony 147 66 0.002 3.56 0.326 0.066

 Arsenic 147 65 0.001 16.4 0.843 0.057

 Beryllium 147 38 0.0005 3.87 0.300 0.034

 Cadmium 147 74 0.002 57,100 900 0.148

 Chromium 147 115 0.007 108,000 1,951 1.57

 Copper 147 135 0.007 141,000 2,552 4.26

 Cyanide 8 7 0.027 4.30 0.751 0.143

 Lead 147 79 0.010 7,150 178 2.48

 Mercury 147 31 0.000 0.032 0.003 0.0008

 Nickel 147 111 0.007 84,623 2,837 3.18

 Selenium 147 36 0.001 8.00 0.551 0.036

 Silver 147 50 0.004 14.4 0.572 0.097

 Thallium 147 21 0.001 2.83 0.196 0.021

 Zinc 146 133 0.005 53,200 1,121 2.84

 Conventional Pollutants

 BOD 5-Day (Carbonaceous) 49 34 4.29 60,400 6,596 1,625

 Oil And Grease 79 54 0.315 260 19.4 4.70

 Oil And Grease (As HEM) 51 23 6.39 1,140 208 82.0

 pH 56 56 0.010 14.4 7.50 8.53

 Total Suspended Solids 143 124 5.00 110,000 1,742 115

 Nonconventional Organic Pollutants

 1,2:3,4-Diepoxybutane 57 1 0.251 0.251 0.251 0.251

 1,4-Dinitrobenzene 57 2 1.07 2.96 2.02 2.02

 1,4-Dioxane 57 4 0.304 2.80 1.10 0.643

 1-Bromo-2-Chlorobenzene 57 5 0.012 0.978 0.317 0.057

 1-Bromo-3-Chlorobenzene 57 4 0.031 0.490 0.193 0.126

 1-Methylfluorene 57 1 0.035 0.035 0.035 0.035

 1-Methylphenanthrene 57 1 0.027 0.027 0.027 0.027

 2-Butanone 57 15 0.070 26.1 3.84 1.05

 2-Hexanone 57 1 5.02 5.02 5.02 5.02

 2-Methylnaphthalene 57 2 0.067 0.220 0.143 0.143

 2-Propanone 57 32 0.052 250 10.4 0.465

 3,6-Dimethylphenanthrene 57 1 0.013 0.013 0.013 0.013

 4-Methyl-2-Pentanone 57 8 0.052 2.78 0.565 0.128 
5.0 - Wastewater Characteristics

Table 5-12 (Continued)

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-25

 Nonconventional Organic Pollutants (continued)

 Alpha-Terpineol 56 1 1.40 1.40 1.40 1.40

 Aniline 57 6 0.015 3.27 0.728 0.225

 Benzoic Acid 57 11 0.051 8,098 754 1.109

 Benzyl Alcohol 57 4 0.012 0.393 0.195 0.189

 Carbon Disulfide 57 1 0.053 0.053 0.053 0.053

 Dibenzofuran 57 1 0.140 0.140 0.140 0.140

 Dibenzothiophene 57 1 0.011 0.011 0.011 0.011

 Diphenylamine 57 1 0.032 0.032 0.032 0.032

 Hexanoic Acid 57 6 0.012 31.5 9.08 5.02

 Isobutyl Alcohol 57 1 0.012 0.012 0.012 0.012

 m+p Xylene 42 1 0.059 0.059 0.059 0.059

 m-Xylene 15 2 0.018 0.020 0.019 0.019

 Methyl Methacrylate 57 5 0.012 0.797 0.471 0.586

 n,n-Dimethylformamide 57 2 0.032 0.123 0.078 0.078

 n-Decane 57 3 0.083 3.51 1.32 0.360

 n-Docosane 57 2 0.021 0.051 0.036 0.036

 n-Dodecane 57 2 0.024 1.27 0.648 0.648

 n-Eicosane 57 2 0.020 0.956 0.488 0.488

 n-Hexadecane 57 1 0.200 0.200 0.200 0.200

 n-Nitrosomethylphenylamine 57 1 1.36 1.36 1.36 1.36

 n-Nitrosomorpholine 57 1 0.040 0.040 0.040 0.040

 n-Octadecane 57 1 0.132 0.132 0.132 0.132

 n-Tetracosane 57 1 0.055 0.055 0.055 0.055

 n-Tetradecane 57 2 0.044 0.114 0.079 0.079

 o+p Xylene 15 2 0.010 0.910 0.460 0.460

 o-Cresol 57 3 0.023 0.195 0.085 0.039

 o-Toluidine 57 1 0.030 0.030 0.030 0.030

 o-Xylene 42 1 0.048 0.048 0.048 0.048

 p-Cresol 57 8 0.011 2.69 0.493 0.153

 p-Nitroaniline 57 2 0.051 26.1 13.1 13.1

 Resorcinol 57 2 1.24 4.12 2.68 2.68

 Tripropyleneglycol Methyl Ether 57 7 0.245 100 33.5 20.1

 Nonconventional Metal Pollutants

 Aluminum 147 116 0.027 34,900 1,283 3.84
Table 5-12 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-26

 Nonconventional Metal Pollutants (continued)

 Barium 147 122 0.001 259 3.60 0.088

 Boron 147 122 0.017 17800 561 0.858

 Calcium 147 143 0.146 1,936 78.3 23.9

 Cobalt 147 79 0.003 4700 67.3 0.530

 Gold 1 1 0.392 0.392 0.392 0.392

 Iron 147 135 0.008 374,000 5,892 3.66

 Magnesium 147 124 0.085 960 66.8 14.6

 Manganese 147 119 0.001 20,600 265 0.319

 Molybdenum 147 89 0.006 197 5.38 0.205

 Sodium 147 145 1.25 383,000 16,367 534.0

 Tin 147 71 0.006 22,670 1,090 1.88

 Titanium 147 97 0.002 13,250 223 0.177

 Vanadium 147 71 0.004 1,495 25.5 0.062

 Yttrium 147 30 0.001 2.11 0.171 0.038

 Other Nonconventional Pollutants

 Acidity 74 45 2.00 600,000 106,486 39,600

 Ammonia As Nitrogen 70 52 0.145 43,000 2,269 16.0

 Chemical Oxygen Demand

 (COD) 82 77 6.90 600,000 32,696 4,700

 Chloride 79 62 1.00 328,300 14,478 80.0

 Fluoride 79 66 0.140 55,500 1,653 3.50

 Hexavalent Chromium 52 9 0.008 0.430 0.090 0.025

 Sulfate 107 90 2.40 755,000 35,877 275

 Total Alkalinity 74 48 2.00 890,000 75,352 435

 Total Dissolved Solids 143 141 87 1,000,000 114,066 23,900

 Total Kjeldahl Nitrogen 61 52 0.480 40,000 3,158 53.8

 Total Organic Carbon (TOC) 50 49 3.70 54,000 10,076 1,380

 Total Petroleum Hydrocarbons

 (As SGT-HEM) 51 9 8.88 352 90.2 25.2

 Total Phosphorus 34 25 0.020 11,000 809 7.50

 Total Recoverable Phenolics 73 53 0.006 135 5.48 0.140

 Total Sulfide 2 1 3.00 3.00 3.00 3.00

Source: MP&M sampling program.
5.0 - Wastewater Characteristics

5-27

Table 5-13

Analytical Data from Rinses Generating

General Metal-Bearing Wastewater

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,2-Diphenylhydrazine 113 1 0.096 0.096 0.096 0.096

 1,4-Dichlorobenzene 113 1 0.013 0.013 0.013 0.013

 Bis(2-Ethylhexyl) Phthalate 113 7 0.011 0.281 0.106 0.053

 Bromodichloromethane 113 29 0.010 0.030 0.018 0.018

 Chloroform 113 62 0.010 0.081 0.025 0.022

 Chloromethane 113 2 0.051 0.102 0.076 0.076

 Di-n-butyl Phthalate 113 4 0.157 0.190 0.176 0.178

 Di-n-octyl Phthalate 113 1 0.013 0.013 0.013 0.013

 Dibromochloromethane 113 24 0.010 0.026 0.016 0.016

 Diethyl Phthalate 113 1 0.049 0.049 0.049 0.049

 Methylene Chloride 113 1 0.011 0.011 0.011 0.011

 Phenol 112 9 0.010 2.00 0.264 0.022

 Trichloroethene 113 6 0.010 0.021 0.016 0.017

 Priority Metal Pollutants

 Antimony 253 41 0.002 0.116 0.026 0.009

 Arsenic 253 65 0.001 0.312 0.019 0.009

 Beryllium 253 18 0.001 0.059 0.010 0.002

 Cadmium 253 58 0.002 8,053 139 0.009

 Chromium 253 144 0.005 21.8 1.06 0.102

 Copper 253 227 0.003 560 16.2 0.201

 Cyanide 14 11 0.020 135 28.3 0.830

 Lead 253 64 0.002 56.6 1.72 0.099

 Mercury 253 23 0.000 0.004 0.001 0.00048

 Nickel 253 162 0.005 2,620 45.1 0.136

 Selenium 253 39 0.001 0.072 0.011 0.003

 Silver 253 49 0.005 7.20 0.325 0.012

 Thallium 253 20 0.001 0.039 0.007 0.002

 Zinc 253 188 0.002 13,700 127 0.142

 Conventional Pollutants

 BOD 5-day (Carbonaceous) 112 50 1.07 873 83.0 11.6
Table 5-13 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-28

 Conventional Pollutants (continued)

 Oil And Grease 86 59 0.295 91.0 9.36 3.80

 Oil And Grease (As HEM) 117 28 6.23 800 58.3 10.9

 pH 122 122 0.25 13.3 6.69 6.84

 Total Suspended Solids 250 157 2.00 6,920 141 20.0

 Nonconventional Organic Pollutants

 1,4-Dioxane 113 2 0.132 2.02 1.08 1.08

 2-Butanone 113 12 0.066 0.550 0.195 0.124

 2-Propanone 113 8 0.052 11.5 1.59 0.071

 Benzoic Acid 113 4 0.126 4.31 1.63 1.05

 Benzyl Alcohol 113 2 0.014 0.014 0.014 0.014

 Carbon Disulfide 113 2 0.062 0.354 0.208 0.208

 Dibenzofuran 113 1 0.010 0.010 0.010 0.010

 Hexanoic Acid 113 3 0.013 0.332 0.147 0.096

 n,n-dimethylformamide 113 5 0.025 0.115 0.045 0.028

 n-decane 113 1 0.012 0.012 0.012 0.012

 n-docosane 113 1 0.012 0.012 0.012 0.012

 n-nitrosopiperidine 113 1 0.020 0.020 0.020 0.020

 o-anisidine 113 1 0.025 0.025 0.025 0.025

 p-cresol 113 6 0.014 0.063 0.038 0.040

 Pentamethylbenzene 113 1 0.036 0.036 0.036 0.036

 Safrole 113 1 0.085 0.085 0.085 0.085

 Thianaphthene 113 1 0.010 0.010 0.010 0.010

 Toluene, 2,4-Diamino- 113 1 6.56 6.56 6.56 6.56

 Tripropyleneglycol Methyl Ether 113 1 8.48 8.48 8.48 8.48

 Nonconventional Metal Pollutants

 Aluminum 253 182 0.022 321 5.85 0.214

 Barium 253 208 0.0007 2.90 0.065 0.036

 Boron 253 187 0.012 363 5.34 0.193

 Calcium 253 245 0.033 361 32.9 23.9

 Cobalt 253 53 0.003 11.0 0.744 0.032

 Iron 253 193 0.003 2,810 40.1 0.323 

 Magnesium 253 229 0.078 130 10.4 8.59

 Manganese 253 163 0.001 135 3.33 0.027

 Molybdenum 253 68 0.003 13.4 0.414 0.022
Table 5-13 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-29

 Nonconventional Metal Pollutants (continued)

 Sodium 253 249 0.277 85,300 1,179 63.3

 Tin 253 73 0.005 6,070 103 0.067

 Titanium 253 90 0.002 18.1 0.879 0.014

 Vanadium 253 31 0.004 1.10 0.142 0.016

 Yttrium 253 15 0.001 0.870 0.066 0.003

 Other Nonconventional Pollutants

 Acidity 77 50 1.00 90,100 3,397 115

 Amenable Cyanide 5 5 0.830 135 60.7 61.5

 Ammonia as Nitrogen 104 51 0.100 729 29.9 2.39

 Chemical Oxygen Demand (COD) 140 113 5.20 73,000 1,041 49.0

 Chloride 84 83 1.20 20,000 452 30.0

 Fluoride 85 71 0.180 60.0 3.58 1.00

 Hexavalent Chromium 117 22 0.011 0.590 0.054 0.020

 Sulfate 149 143 2.33 28,400 534 58.8

 Total Alkalinity 75 57 8.00 8,600 507 72.0

 Total Dissolved Solids 250 250 20.0 260,000 3,799 629

 Total Kjeldahl Nitrogen 102 56 0.10 6,720 151 8.07

 Total Organic Carbon (TOC) 112 101 1.16 5,800 195 10.7

 Total Petroleum Hydrocarbons

 (As SGT-HEM) 117 13 5.25 316 43.3 9.52

 Total Phosphorus 36 26 0.026 720 54.0 6.65

 Total Recoverable Phenolics 132 53 0.005 2.85 0.083 0.012

 Weak-acid Dissociable Cyanide 3 3 52.9 140 108 131

Source: MP&M sampling data.

5.5.2 General Metal-Bearing Raw Wastewater Characteristics

Typically, MP&M facilities with well-designed treatment systems segregate their

waste streams by type and treat them in preliminary treatment units designed to treat the particular

characteristic as discussed in Sections 5.1 through 5.4. After preliminary treatment, MP&M

facilities typically commingle the wastewater with general process wastewater generated from the

unit operations described in Section 5.5.1 and treat it in an end-of-pipe treatment system. 

Generally, the end-of-pipe treatment consists of chemical precipitation and sedimentation. Where

high concentrations of metals are present in the wastewater, facilities may employ preliminary

batch chemical precipitation and sedimentation to ensure that the high concentrations will not
5.0 - Wastewater Characteristics

5-30

cause a process upset to the end-of-pipe treatment system. Section 8.2.2 discusses metal-bearing

wastewater treatment technologies used in the MP&M industry. Table 5-14 summarizes the data

obtained from sampling the influent to end-of-pipe chemical precipitation systems. (See Section

10.0 for a discussion of achievable effluent concentrations following chemical precipitation.)
5.0 - Wastewater Characteristics

5-31

Table 5-14

Analytical Data for General Metal-Bearing Treatment 

Influent Wastewater Streams

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

 Priority Organic Pollutants

 1,1,1-Trichloroethane 137 6 0.019 0.084 0.053 0.053

 1,1,2,2-Tetrachloroethane 137 1 12.1 12.1 12.1 12.1

 1,1-Dichloroethene 137 2 0.011 0.748 0.379 0.379

 4-Chloro-3-Methylphenol 136 9 0.011 1.14 0.183 0.076

 Anthracene 137 1 0.104 0.104 0.104 0.104

 Benzene 137 1 0.025 0.025 0.025 0.025

 Bis(2-Chloroethyl) Ether 137 1 0.016 0.016 0.016 0.016

 Bis(2-Ethylhexyl) Phthalate 137 20 0.008 0.298 0.051 0.014

 Bromodichloromethane 137 14 0.011 0.143 0.026 0.016

 Butyl Benzyl Phthalate 137 2 0.009 0.010 0.009 0.009

 Chloroform 137 63 0.010 0.824 0.102 0.032

 Chloromethane 137 1 0.011 0.011 0.011 0.011

 Di-n-butyl Phthalate 137 3 0.007 0.066 0.044 0.058

 Di-n-octyl Phthalate 137 1 0.012 0.012 0.012 0.012

 Dibromochloromethane 137 6 0.014 0.065 0.024 0.016

 Diethyl Phthalate 134 1 0.038 0.038 0.038 0.038

 Ethylbenzene 137 5 0.006 0.335 0.074 0.010

 Fluorene 137 1 0.045 0.045 0.045 0.045

 Methylene Chloride 137 10 0.008 0.172 0.043 0.023

 Naphthalene 137 3 0.012 0.054 0.035 0.038

 Phenanthrene 137 3 0.041 0.112 0.071 0.060

 Phenol 139 19 0.016 0.634 0.099 0.029

 Tetrachloroethene 137 8 0.015 1.11 0.306 0.081

 Toluene 137 6 0.009 2.77 0.533 0.019

 Trichloroethene 137 3 0.019 0.023 0.021 0.021

 Priority Metal Pollutants

 Antimony 219 77 0.002 1.13 0.062 0.019

 Arsenic 223 88 0.001 0.530 0.026 0.009

 Beryllium 223 62 0.0002 3.23 0.235 0.004

 Cadmium 223 113 0.001 323 6.26 0.065
Table 5-14 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-32

 Priority Metal Pollutants (continued)

 Chromium 223 213 0.012 1,350 15.1 1.27

 Copper 223 221 0.013 344 16.3 1.08

 Lead 223 149 0.002 159 3.44 0.176

 Mercury 221 48 0.00003 0.012 0.0009 0.0003

 Nickel 223 215 0.012 2,101 30.5 1.52

 Selenium 219 35 0.001 0.090 0.019 0.007

 Silver 223 134 0.005 4.23 0.401 0.046

 Thallium 219 24 0.001 0.112 0.011 0.002

 Zinc 223 212 0.009 1,540 17.8 0.945

 Conventional Pollutants

 BOD 5-Day (Carbonaceous) 133 86 2.40 609 64.4 26.0

 Oil And Grease (as HEM) 205 133 0.570 32,000 507 11.9

 Total Suspended Solids 222 202 4.00 8,920 569 96.8

 Nonconventional Organic Pollutants

 1 4-Dioxane 132 2 0.033 0.118 0.0755 0.0755

 1-Methylfluorene 132 2 0.111 0.189 0.150 0.150

 1-Methylphenanthrene 132 2 0.092 0.181 0.136 0.136

 2-Butanone 132 8 0.056 2.45 0.481 0.079

 2-Methylnaphthalene 132 2 0.076 0.205 0.140 0.140

 2-Propanone 132 74 0.051 16.7 0.952 0.151

 3,6-Dimethylphenanthrene 132 2 0.019 0.062 0.041 0.041

 4-Methyl-2-Pentanone 132 10 0.120 1.36 0.308 0.181 

 Acetophenone 132 1 0.073 0.073 0.073 0.073

 Alpha-Terpineol 132 5 0.013 0.087 0.051 0.054

 Aniline 132 1 0.013 0.013 0.013 0.013

 Benzoic Acid 132 45 0.053 46.8 1.38 0.224

 Benzyl Alcohol 132 8 0.011 0.145 0.039 0.015

 Beta-Naphthylamine 130 1 0.104 0.104 0.104 0.104

 Biphenyl 132 1 0.011 0.011 0.011 0.011

 Carbon Disulfide 132 10 0.016 3.92 0.505 0.058

 Dibenzothiophene 132 2 0.015 0.025 0.020 0.020

 Diphenylamine 132 1 0.033 0.033 0.033 0.033

 Hexanoic Acid 132 21 0.010 0.461 0.056 0.017

 m-xylene 71 1 0.016 0.016 0.016 0.016
Table 5-14 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-33

 Nonconventional Organic Pollutants (continued)

 Methyl Methacrylate 132 1 0.019 0.019 0.019 0.019

 n,n-dimethylformamide 132 8 0.012 0.581 0.093 0.016

 n-decane 132 1 0.031 0.031 0.031 0.031

 n-docosane 132 2 0.013 0.026 0.019 0.019

 n-dodecane 132 7 0.044 0.772 0.243 0.088

 n-eicosane 132 9 0.014 0.181 0.043 0.020

 n-hexacosane 132 6 0.022 0.037 0.033 0.034

 n-hexadecane 132 13 0.010 0.631 0.127 0.061

 n-nitrosomethylethylamine 132 2 0.019 0.023 0.021 0.021

 n-nitrosomorpholine 132 2 0.011 0.028 0.020 0.020

 n-octacosane 132 2 0.035 0.036 0.036 0.036

 n-octadecane 132 19 0.011 0.493 0.090 0.027

 n-tetracosane 132 4 0.012 0.021 0.017 0.018

 n-tetradecane 132 10 0.017 1.01 0.227 0.104

 n-triacontane 132 2 0.015 0.031 0.023 0.023

 o+p-xylene 71 3 0.013 0.023 0.017 0.014

 o-toluidine 132 1 0.013 0.013 0.013 0.013

 p-chloroaniline 132 1 0.098 0.098 0.098 0.098

 p-cresol 132 10 0.013 0.030 0.019 0.017

 p-cymene 132 3 0.015 0.054 0.030 0.020 

 Styrene 132 5 0.013 0.188 0.057 0.025

 Trichlorofluoromethane 137 7 0.025 0.109 0.042 0.032

 Tripropyleneglycol Methyl Ether 132 23 0.064 5.21 1.83 1.05

 Nonconventional Metal Pollutants

 Aluminum 223 212 0.055 571 11.1 2.85

 Barium 223 198 0.010 9.91 0.201 0.069

 Boron 212 198 0.057 206 4.14 0.746

 Calcium 223 223 4.77 832 74.1 37.8

 Cobalt 223 95 0.002 25.8 0.924 0.021

 Gold 20 10 0.013 0.150 0.056 0.038

 Iron 223 223 0.061 3,880 102 4.96

 Magnesium 223 218 0.349 3,360 88.7 10.3

 Manganese 223 222 0.004 47.3 1.47 0.2315

 Molybdenum 223 149 0.003 3.06 0.253 0.039
Table 5-14 (Continued)

5.0 - Wastewater Characteristics

Pollutant Parameter

No. of

Samples

Analyzed

No. of

Detects

Concentrations (mg/L)

Minimum Maximum Mean Median

5-34

 Nonconventional Metal Pollutants (continued)

 Palladium 10 8 0.053 0.229 0.114 0.085

 Sodium 223 223 20.1 9,600 471 216

 Tin 212 137 0.004 75.3 4.85 0.189

 Titanium 212 155 0.002 76.4 1.85 0.052

 Vanadium 223 58 0.0016 1.19 0.067 0.014

 Yttrium 212 57 0.00084 0.085 0.010 0.003

 Other Nonconventional Pollutants

 Acidity 73 54 7.00 24,770 1,862 140

 Amenable Cyanide 7 5 0.012 0.129 0.085 0.092

 Ammonia As Nitrogen 91 88 0.040 320 19.3 2.56

 Chemical Oxygen Demand (COD) 205 196 1.50 13,000 541 122

 Chloride 80 77 4.50 9,500 410 140

 Fluoride 80 79 0.130 100 4.49 1.55

 Hexavalent Chromium 133 50 0.010 21.0 0.771 0.060

Sulfate 136 130 18.0 19,000 586 268

 Total Alkalinity 74 47 2.39 510 126 96.0

 Total Dissolved Solids 222 222 19.0 34,000 2,426 1,030

 Total Kjeldahl Nitrogen 85 82 0.110 160 14.9 6.69

 Total Organic Carbon (TOC) 128 99 3.57 394 59.9 32.3

 Total Petroleum Hydrocarbon (As SGT-HEM) 133 49 5.00 93.0 21.2 10.3

 Total Phosphorus 86 84 0.020 525 30.3 5.2

 Total Recoverable Phenolics 189 110 0.006 13.0 0.387 0.047

 Total Sulfide 28 2 2.00 4.00 3.00 3.00

Source: MP&M sampling program.
6.0 - Industry Subcategorization

6-1

6.0 INDUSTRY SUBCATEGORIZATION 

This section discusses the subcategorization of the MP&M Point Source Category. 

Section 6.1 discusses the methodology and factors considered when determining the subcategories and

Section 6.2 describes facilities in each subcategory.

6.1 Methodology and Factors Considered for Basis of Subcategorization

To provide a method for addressing variations between products, raw materials

processed, and other factors that result in distinctly different effluent characteristics, EPA divided the

MP&M Point Source Category into groupings called “subcategories.” Each subcategory has a uniform

set of effluent limitations that take into account technological achievability and economic impacts unique

to that subcategory. The Clean Water Act (CWA) requires EPA, in developing effluent limitations

guidelines and pretreatment standards, to consider a number of different subcategorization factors. The

statute also authorizes EPA to take into account other factors the Agency deems appropriate. EPA

considered the following factors in its evaluation of potential MP&M subcategories: 

C Unit operation;

C Activity;

C Raw materials;

C Products;

C Size of site;

C Geographic location;

C Facility age;

C Nature of the waste generated;

C Economic impacts;

C Treatment costs;

C Total energy requirements;

C Air pollution control methods;

C Solid waste generation and disposal; and

C Publicly Owned Treatment Works (POTW) burden.

As a result, EPA has determined that a basis exists for dividing the MP&M category

into the following subcategories for the proposed rule, as shown in Table 6-1.
6.0 - Industry Subcategorization

6-2

Table 6-1

 Proposed Subcategories

Facilities that Generate Metal-Bearing Wastewater

(With or Without Oil-Bearing Wastewater)

Facilities that Generate Only Oil-Bearing

Wastewater

General Metals Oily Wastes

Metal Finishing Job Shops Railroad Line Maintenance

Non-Chromium Anodizing Shipbuilding Dry Dock

Printed Wiring Board

Steel Forming and Finishing

6.1.1 Factors Contributing to Subcategorization

EPA found two basic types of waste streams in the industry: 1) wastewater with high

metals content (metal-bearing), and 2) wastewater with low concentration of metals, and high oil and

grease content (oil-bearing). The type of wastewater a facility generates is directly related to the unit

operations it performs. For example, unit operations such as machining, grinding, aqueous degreasing,

and impact or pressure deformation tend to generate a wastewater with high oil and grease (and

associated organic pollutants) loadings but relatively lower concentrations of metal pollutants. Other

unit operations such as electroplating, conversion coating, chemical etching and milling, and anodizing

generate higher metals loadings with moderate or low oil and grease concentrations or generate

wastewater containing both metals and oil and grease.

Although many facilities generate both metal- and oil-bearing wastewater, a large

number of facilities, typically machine shops and maintenance and repair facilities, only generate oilbearing wastewater. Since the wastewater at these facilities primarily contains oil and grease and other

organic constituents, these facilities use treatment technologies that focus on oil removal only and do not

include the chemical precipitation step needed to treat metal-bearing wastewater. These treatment

technologies generally include ultrafiltration, or chemical emulsion breaking followed by either gravity

flotation, coalescing plate oil/water separators, or dissolved air flotation (DAF). Therefore, EPA first

divided the industry on the basis of unit operations performed and the nature of the wastewater

generated, resulting in the following two groups: (1) metal-bearing with or without oily and organic

constituents group; and (2) oil-bearing only group. EPA then performed an analysis to identify any

significant differences in the subcategorization factors within the two basic groups. Section 6.2.6

identifies the unit operations that EPA believes to generate only oil-bearing wastewater to generate

metal-bearing wastewater. EPA considers MP&M facilities that perform MP&M unit operations other

than those mentioned in Section 6.2.6 to generate metal-bearing wastewater.
6.0 - Industry Subcategorization

6-3

Metal-Bearing Wastewater (With or Without Oil-Bearing Wastewater)

When looking at facilities generating metal-bearing wastewater (with or without oilbearing wastewater), EPA identified five groups of facilities that could potentially be subcategorized by

dominant product, raw materials used, and/or nature of the waste generated. In two groups, EPA also

considered economic impacts as a factor in subcategorization because of the reduced ability of these

facilities to afford treatment costs. Within the group of facilities with metal bearing wastewater EPA

also identified one group where the number of facilities not currently covered by an existing effluent

guidelines regulation was large enough to present an unacceptable burden to POTWs. 

Based on the currently available data, EPA divided the metal-bearing (with or without

oil-bearing wastewater) MP&M facilities into the following subcategories: non-chromium anodizing

facilities; metal finishing job shops; printed wiring board facilities; steel forming and finishing facilities;

and general metals facilities. EPA describes its rationale for subcategorizing each of these groups

below (see Section 6.2 for additional detailed discussion and applicability). 

The non-chromium anodizers differ from other MP&M facilities in that all of their

products are primarily of one metal type, anodized aluminum, and most importantly, they do not use

chromic acid, dichromate sealants, or other process solutions containing significant concentrations of

chromium in their anodizing process. Based on EPA’s limited data for these facilities, the Agency

expects that these facilities have very low levels of metals (with the exception of aluminum) or toxic

organic pollutants in their wastewater discharges. EPA determined that other MP&M facilities had

much greater concentrations of a wider variety of metals. Table 6-2 illustrates this point by providing

the percentage of facilities using multiple metal types by subcategory.
6.0 - Industry Subcategorization

6-4

Table 6-2

Percentage of Facilities Using Multiple Metal Types by Subcategory

Proposed Subcategory Number of Metal Types Processed

0 1 2 3 4 5-

10

>10

Shipbuilding Dry Docks 0 0 25 50 0 25 0

General Metals 0 51 23 13 4 10 0

Steel Forming and Finishing 0 55 25 14 3 3 0

Metal Finishing Job Shop 0 7 24 23 4 41 1

Non-Chromium Anodizer 0 76 24 0 0 0 0

Oily Wastes 32 13 53 1 <1 0 0

Printed Wiring Boards 0 1 0 49 9 40 1

Railroad Line Maintenance <1 98 1 <1 0 0 0

 Source: MP&M Survey Database

In addition, non-chromium anodizing facilities require much larger wastewater treatment

systems than other metal-bearing MP&M facilities to remove the large amounts of aluminum and low

levels of alloy metals generated in their wastewater. The need for larger treatment systems results in

higher costs and large economic impacts for this proposed subcategory. EPA found that as many as 60

percent of the non-chromium anodizers could close as a result of complying with the regulatory options

considered.

Therefore, based on the difference in raw materials used, product produced, nature of

the waste generated (i.e., low levels of pollutants discharged), treatment costs, and projected economic

impacts, EPA concluded that a basis exists for subcategorizing the non-chromium anodizing facilities in

the MP&M industry. 

EPA investigated whether to subcategorize the metal finishing and electroplating job

shops covered currently by the metal finishing (40 CFR 433) and electroplating (40 CFR 413) effluent

guidelines. Although these facilities have metal types that require the same treatment technologies as

many other metal-bearing facilities, EPA determined that they can be different due to the variability of

their raw materials and products as well as the slightly higher economic impacts incurred as compared

to other MP&M facilities. As discussed in Section 6.2, this subcategory includes only those facilities

that perform the six operations defining the applicability of the metal finishing and electroplating effluent

guidelines and that are “job shops” as defined in the metal finishing effluent guidelines (i.e., they own less

than 50 percent of the products processed on site on an annual area basis). 
6.0 - Industry Subcategorization

6-5

Because these facilities are job shops and work on a contract basis, they cannot always

predict the type of plating or other finishing operations required. In addition, because these facilities

work on a large variety of metal types from various customers, their wastewater characteristics can

vary from week to week (or even day to day). Table 6-2 demonstrates the variety of metal types

processed at metal finishing job shops as compared to the rest of the industry. (Note that shipbuilding

dry docks and printed wiring board facilities also process a wide variety of metal types. EPA also

chose to subcategorize these groups for reasons discussed below.) EPA performed sampling to

specifically identify the variability in the wastewater generated at metal finishing job shops, and found

that the variability factors calculated solely on the analytical wastewater sampling data from metal

finishing and electroplating job shops are higher for most pollutant parameters than those calculated for

similar metal-bearing subcategories (e.g., General Metals) (see Section 10.1 for a discussion of EPA’s

job shop variability wastewater sampling and Section 10.3 for a discussion on determining limits and

variability factors). In addition, EPA found that up to 10 percent of the indirect discharging metal

finishing job shops could close as a result of compliance with the proposed regulation. Therefore, EPA

concluded that it has an appropriate basis for subcategorizing metal finishing and electroplating job

shops.

EPA determined that there is a basis for subcategorizing the printed wiring board

facilities based on raw materials, unit operations performed, primary product, and nature of the waste

generated. First, as shown in Table 6-3, these facilities process a more consistent mix of metal types

(primarily copper, tin, and lead) than other metal-bearing wastewater generating MP&M facilities. 

EPA concluded that this consistent mix of metal types enables printed wiring board facilities to tailor

their treatment technology and incorporate more of the advanced pollution prevention and recovery

technologies (e.g., ion exchange). 
6.0 - Industry Subcategorization

6-6

Table 6-3

Percentage of MP&M Facilities by Subcategory Using Each Metal Type

Metal

Subcategory

Shipbuilding

Dry Docks

General

Metals

 Steel

Forming 

and 

Finishing

Metal

Finishing

Job Shop

NonChromium

Anodizer

Oily

Wastes

Printed

Wiring

Boards

Railroad

Line

Maintenance

Aluminum 25 38 3 60 88 46 6 1

Beryllium 0 0 0 1 0 0 0 0

Cadmium 25 1 3 11 0 0 0 0

Chromium 50 6 11 27 0 1 3 0

Cobalt 0 3 3 0 0 1 1 0

Copper 75 28 10 53 0 12 99 6

Gold 0 4 0 14 0 0 82 0

Indium 0 0 0 0 0 0 0 0

Iron 100 82 100 87 36 86 11 100

Lead 0 4 1 9 0 1 94 6

Magnesium 0 2 0 5 0 2 0 0

Manganese 0 0 0 0 0 0 2 0

Molybdenum 25 0 0 0 0 0 6 0

Nickel 75 13 5 53 0 6 82 0

Palladium 0 1 0 0 0 0 7 0

Platinum 0 0 0 1 0 0 0 0

Rhodium 0 0 0 6 0 0 1 0

Ruthenium 0 0 0 0 0 0 1 0

Selenium 0 0 0 0 0 0 0 0

Silver 25 2 0 16 0 0 11 0

Tantalum 0 1 0 0 0 0 0 0

Tin 0 11 5 30 0 0 97 0

Titanium 0 3 3 3 0 1 0 0

Tungsten 0 1 0 0 0 1 0 0

Yttrium 0 0 0 1 0 0 8 0

Zinc 25 14 30 54 0 1 3 0

Zirconium 0 0 0 0 0 0 0 0

Source: MP&M Survey Database
6.0 - Industry Subcategorization

6-7

Printed wiring board facilities generally work with copper-clad laminate material,

allowing them to target copper for removal in their wastewater treatment systems or recover the copper

using in-process ion exchange. Second, these facilities apply, develop, and strip photo resist - a set of

unit operations that is unique to this subcategory. This process produces a higher concentration of a

more consistent group of organic constituents than other facilities in the metal-bearing group. Finally,

the nature of the wastewater generated at these facilities may also be different because these facilities

perform more lead-bearing operations (e.g., lead/tin electroplating, wave soldering) than other MP&M

facilities.

Steel forming and finishing is another proposed subcategory under the metal- bearing

group of MP&M facilities. These facilities perform both cold forming and finishing operations on steel

at stand-alone facilities as well as at steel manufacturing facilities. EPA formerly covered these facilities

under the 1982 Iron and Steel Manufacturing effluent guidelines (40 CFR Part 420). Typical

operations include: acid pickling, annealing, conversion coating (e.g., zinc phosphate, copper sulfate),

hot dip coating and/or electroplating of steel wire or rod, heat treatment, welding, drawing, patenting,

and oil tempering. EPA concluded that the basis for subcategorization is the difference in the raw

material and primary product at these facilities. Facilities in this subcategory primarily process steel

and, for the most part, produce uniformly shaped products such as wire, rod, bar, pipe, and tube. In

addition, this is the only subcategory for which EPA is proposing to cover forming operations under the

MP&M regulations. Effluent guidelines specific to forming operations exist for all other common metal

types (e.g., Aluminum Forming (40 CFR Part 467); Copper Forming (40 CFR Part 468); and

Nonferrous Metals Forming & Metal Powders (40 CFR Part 471)). 

After subcategorizing non-chromium anodizing facilities, metal finishing job shops,

printed wiring board facilities, and steel forming and finishing facilities, EPA is proposing to group the

remaining metal-bearing wastewater generating MP&M facilities into a subcategory entitled “General

Metals.” This subcategory would be a “catch-all” for metal-bearing wastewater generating facilities that

do not fall into any of the previous subcategories. For example, wastewater generated from most

manufacturing operations and heavy rebuilding operations (e.g., aircraft, aerospace, auto, bus/truck,

railroad) would be regulated under the proposed General Metals subcategory. Whereas all facilities in

the other four metal-bearing subcategories are currently covered by existing effluent guidelines, only 16

percent of General Metals facilities are covered by 433/413 (with another 10 percent having some

waste streams covered by other metals, effluent guidelines). This means that over 25,000 MP&M

facilities in this subcategory would require new permits (i.e. control mechanisms). EPA recognizes that

this would create a very large burden on POTWs. Therefore, in determining a proposed option for the

General Metals Subcategory, EPA considered the POTW permitting burden associated with proposing

pretreatment standards for over 25,000 facilities (See Section 14.0).

Oil-Bearing Only Group

When evaluating facilities with only oil-bearing wastewater for potential further

subcategorization, EPA identified two types of facilities that were different from the other facilities in
6.0 - Industry Subcategorization

6-8

that group based on size, location, and dominant product or activity. The first type of facility is railroad

line maintenance facilities, and the second performs MP&M operations in shipbuilding dry docks or

similar structures (see Section 6.2.7 and 6.2.8, respectively, for detailed descriptions of these proposed

subcategories). 

Railroad line maintenance facilities perform outdoor light maintenance and cleaning of

railroad cars, engines, and wheel trucks. EPA concluded that there is a basis to subcategorize railroad

line maintenance facilities due to their outdoor location, unit operations performed, and low level of

pollutant loadings discharged to the environment. Unit operations typically performed at railroad line

maintenance facilities include: abrasive blasting, alkaline cleaning for oil removal, aqueous degreasing,

assembly/disassembly, floor cleaning, washing finished products, welding, and collection of storm

water. EPA notes that this proposed subcategory does not include railroad manufacturing facilities or

railroad overhaul/rebuilding facilities. 

The second type of facility is dry docks (and similar structures such as graving docks,

building ways, lift barges, and marine railways): large, outdoor areas, exposed to precipitation, where

shipyards perform final assembly, maintenance, rebuilding, and repair work on large ships and boats. 

EPA believes that a basis exists to subcategorize shipbuilding dry docks and similar structures due to

their size, outdoor location, low level of pollutant loadings discharged to the environment, and the fact

this wastewater is unique to the shipbuilding industry. This proposed subcategory does not include

other MP&M operations that occur at shipyards (e.g., shore-side operations). 

The facilities that generate only oil-bearing wastewater but are not dry docks or

railroad line maintenance facilities fall into the Oily Wastes Subcategory. These facilities discharge only

oil-bearing wastewater and perform only one or more of the unit operations listed in Table 6-4 below.

Table 6-4

Unit Operations Performed by Oily Wastes Facilities

Alkaline Cleaning for Oil Removal Machining

Aqueous Degreasing Pressure Deformation

Corrosion Preventive Coating Solvent Degreasing

Floor Cleaning Testing (e.g., Hydrostatic, Dye Penetrant, Ultrasonic, Magnetic Flux)

Grinding Painting

Heat Treating Steam Cleaning

Impact Deformation Laundering
6.0 - Industry Subcategorization

6-9

Therefore, EPA divided the facilities in the MP&M industry that generate only oilbearing wastewater into the following three subcategories: (1) railroad line maintenance facilities; and

(2) shipbuilding dry docks (and similar structures); (3) oily waste facilities. Following further analysis,

EPA decided not to propose pretreatment standards for indirect dischargers in the railroad line

maintenance and shipbuilding dry dock subcategories and proposed a low flow cutoff of 2 million

gallons per year for indirect dischargers in the Oily Wastes Subcategory. (see Section 14.8 for a

discussion pertaining to pretreatment standards).

6.1.2 Factors That are not a Basis for MP&M Subcategorization

EPA examined the other factors listed earlier in this section for possible basis of

subcategorization. The Agency determined that there is no basis for subcategorizing the MP&M

industry based on the following factors: geographic location, age of facilities, total energy requirements,

air pollution control methods, and solid waste generation and disposal. These factors are discussed

below. In addition, EPA also considered subcategorizing the MP&M industry according to the 18

industrial sectors listed in Section 2.2.5. As discussed in Section 6.1.1, and further discussed below,

EPA determined that subcategorization based on sectors was appropriate for only one sector (printed

wiring board), and for portions of three other sectors (railroad, ships and boats, and job shops). 

Geographic Location

MP&M sites are located throughout the United States. Sites are not limited to any one

geographical location, but approximately half are located east of the Mississippi, with additional

concentrations of sites in Texas, Colorado, and California. EPA did not subcategorize based on

geographic location because location does not affect the ability of sites to comply with the MP&M rule. 

Geographic location may impact costs if additional land is required to install treatment

systems, since the cost of the land will vary depending on whether the site is located in an urban or rural

location. However, the treatment systems used to treat MP&M wastewater typically do not have large

land requirements, as demonstrated by the fact that many MP&M sites are located in urban settings. 

Water availability is another function of geographical location. Limited water supply

encourages efficient use of water. The Agency encourages installing water recycle and reuse practices. 

The proposed treatment options for all subcategories include pollution prevention and water

conservation because these practices tend to reduce treatment costs and improve pollutant removals. 

Facility Age

The percentage of water-discharging facilities by the decade in which they were built is

shown in Figure 6-1. This information is based upon responses to MP&M surveys that reported the

date the facility was built.
6.0 - Industry Subcategorization

6-10

Before 1920

2%

1920s

1%

1930s

3%

1940s

3%

1950s

19%

1960s

7%

1970s

31%

1980s

30%

1990s

4%

Source: MP&M Survey Database.

Note: MP&M surveys were mailed in 1991 and 1996. There are 62,749 wastewater-discharging MP&M sites.

Figure 6-1. Percentage of Wastewater-Discharging Facilities by Decade Built

Most sites have been built since 1970. Although the survey respondents reported a

wide range of ages, these sites must be continually modernized to remain competitive. Most of the sites

EPA visited during the MP&M site visit program had recently modernized some area of their site. 

Modernizing production processes and air pollution control equipment results in generation of similar

wastes among all sites of various ages. Therefore, EPA did not select facility age as a basis for

subcategorization.

Total Energy Requirements

EPA did not select total energy requirements as a basis for subcategorization because

EPA does not expect energy requirements to vary widely on a production normalized basis. The

subcategorization scheme that EPA is proposing should account for any variations in energy

requirements (e.g., differences in treatment system energy requirements for metal-bearing streams

versus oily waste streams). The estimated impacts of this regulation on energy consumption in the
6.0 - Industry Subcategorization

6-11

United States is an energy increase of approximately 0.01 percent (see Section 13.0). EPA estimated

the energy requirements associated with each MP&M technology option and considered these in

estimating compliance costs (see Section 11.0). 

Air Pollution Control Methods

Many sites control air emissions using wet air pollution control units that affect the

wastewater flow rate from the site. However, based on data collected during the MP&M sampling

program, wastewater generated by these devices does not affect the effectiveness of technologies used

to control MP&M wastewater pollutant loadings. EPA considers wet air pollution control units

additional unit operations within the MP&M category, but not as a basis of subcategorizing the

category. 

Industrial Sectors

EPA considered subcategorizing the MP&M category by industrial sector (e.g.,

aerospace, aircraft, bus and truck, electronic equipment, hardware, household equipment, instruments,

job shops, mobile industrial equipment, motor vehicles, office machines, ordnance, precious metals and

jewelry, printed wiring boards, railroad, ships and boats, stationary industrial equipment, and

miscellaneous metal products). Sectors are broadly defined and not only include manufacturing and

repair facilities within the sector (e.g., shipbuilding facilities in the ship and boat sector), but also include

facilities that produce products that are used within the sector (e.g., a facility that manufactures

hydraulic pumps used on ships is also in the ship and boat sector). The Agency determined that

subcategorization based solely on industrial sector would require much more detailed subcategorization

scheme than the approach proposed (see below). Adopting a subcategorization scheme based on

industrial sector would complicate the implementation of the limitations and standards because permit

writers might be required to develop facility-specific limitations across multiple subcategories.

The Agency determined that wastewater characteristics, unit operations, and raw

materials used to produce products within a given sector are not always the same from site to site, and

they are not always different from sector to sector. Within each sector, sites can perform a variety of

unit operations on a variety of raw materials. For example, a site in the aerospace sector may primarily

machine aluminum missile components and not perform any surface treatment other than alkaline

cleaning. Another site in that sector may electroplate iron parts for missiles and perform little or no

machining. Wastewater characteristics from these sites may differ because of the different unit

operations performed and different raw materials used. 

Based on the analytical data collected for this rule, EPA has not found a statistically

significant difference in industrial wastewater discharge among industrial sectors when performing similar

unit operations for cadmium, chromium, copper, cyanide, lead, manganese, molybdenum, nickel, oil &

grease, silver, tin, TSS, and zinc. (The analytical data are available in the public record for this

rulemaking.) For example, a facility that performs electroplating in the process of manufacturing office
6.0 - Industry Subcategorization

6-12

machines produces metal-bearing wastewater with similar chemical characteristics as a facility that

performs electroplating in the process of manufacturing a part for a bus. Similarly, a facility that

performs repair and maintenance on a airplane engine produces oil-bearing wastewater that has similar

chemical characteristics to a facility that performs repair and maintenance on construction machinery.

Most MP&M unit operations are not unique to a particular sector and are performed

across all sectors. For example, all sectors may perform several of the major wastewater-generating

unit operations (e.g., alkaline treatment, acid treatment, machining, electroplating). And, for the most

part, the unit operations that are rarely performed (e.g., abrasive jet machining) are not performed in all

sectors, but are also not limited to a single sector. Therefore, a facility in any one of the 18 industrial

sectors can generate metal-bearing or oil-bearing wastewater (or a combination of both) depending on

what unit operations the facility performs. 

In addition, two facilities that may be part of the same sector may generate wastewater

with vastly different chemical characteristics and thus require different types of treatment. For example,

an automobile manufacturer and an automobile repair facility are both part of the motor vehicle sector. 

However, the automobile manufacturer may perform unit operations that generate metal-bearing and

oil-bearing wastewater (aqueous degreasing, electroplating, chemical conversion coating, etc.) while the

automobile repair facility may perform unit operations that only generate oil-bearing wastewater

(machining, aqueous degreasing, impact deformation, painting, etc.). 

Due to the numerous MP&M facilities that could fall under the scope of multiple

sectors, EPA determined that a regulation based on MP&M industrial sector would create a variety of

implementation issues for State and local regulators as well as for those multiple-sector facilities. 

Therefore, as mentioned above, EPA is not proposing to use industrial sector to subcategorize the

industry. 

After dividing facilities in the MP&M industry according to the unit operations

performed (metal-bearing or oil-bearing operations), EPA concluded that raw wastewater has similar

treatability across all of the MP&M sectors. Therefore, a facility that performs electroplating in the

process of manufacturing office machines produces metal-bearing wastewater with similar chemical

characteristics as a facility that performs electroplating in the process of manufacturing a part for a bus. 

Similarly, a facility that performs repair and maintenance on an airplane engine produces oil-bearing

wastewater that has similar chemical characteristics to a facility that performs repair and maintenance on

construction machinery. 

Solid Waste Generation and Disposal

Physical and chemical characteristics of solid waste generated by the MP&M category

are determined by the raw materials, unit operations, and types of air pollution control in use. 

Therefore, this factor does not provide a primary basis for subcategorization. The subcategorization

scheme that EPA is proposing should account for any variations in solid waste generated or disposed. 
6.0 - Industry Subcategorization

6-13

EPA considered the amount of sludge generated as a result of the MP&M technology options, and

included disposal of these sludges in the compliance cost estimates (see Section 11.0) and non-water

quality impact assessments (see Section 13.0). 

6.2 General Description of Facilities in Each Subcategory

Below is a general description of the types of facilities that fall within each of the

proposed subcategories. Sections 11.0 and 12.0 present information on compliance costs and

pollutant reductions associated with the MP&M proposed rule for each subcategory

6.2.1 General Metals Subcategory

As discussed above in Section 6.1, EPA has created the General Metals Subcategory

as a “catch-all” for MP&M facilities that discharge metal-bearing wastewater (with or without oilbearing wastewater) that do not fit the applicability of the Metal Finishing Job Shops, Non-Chromium

Anodizing, Printed Wiring Board, or Steel Forming and Finishing Subcategories. Therefore, the

General Metals Subcategory may include facilities from 17 of the 18 MP&M industrial sectors (i.e., all

except the printed wiring board sector). This subcategory also includes general metals facilities that are

owned and operated by states and municipalities. General metals facilities typically perform

manufacturing or heavy rebuilding of metal products, parts, or machines. Facilities that perform metal

finishing or electroplating operations on site, but do not meet the definition of a job shop (i.e., captive

shops), would fit in the General Metals Subcategory.

EPA estimates that there are approximately 26,000 indirect dischargers and 3,800

direct dischargers that could be covered by this Subcategory. EPA currently regulates 26 percent of

the facilities in this subcategory by existing effluent guidelines. The Agency estimates that, based on

responses to its questionnaires, the Metal Finishing (40 CFR 433) and Electroplating (40 CFR 413)

effluent guidelines cover approximately 16 percent of these facilities, and other metal related effluent

guidelines (such as those discussed in Section 1.2.7. cover a portion of the wastewater discharges at an

additional 10 percent of these facilities. 

EPA is proposing to exclude from the MP&M regulations indirect dischargers that

would fall into the General Metals Subcategory when they discharge less than or equal to 1 million

gallons per year (MGY) of MP&M process wastewater to the POTW (see Section 14.0 for EPA’s

discussion of flow cutoffs). Approximately 23,000 indirect dischargers in the General Metals

Subcategory discharge less than 1 MGY. If EPA did not exclude these facilities, the number of permits

that POTWs would issue would double, greatly increasing their burden. Facilities discharging less than

1 MGY to a POTW, however, are still subject to other applicable pretreatment standards, including

those established under 40 CFR Parts 413 and 433.
6.0 - Industry Subcategorization

6-14

6.2.2 Metal Finishing Job Shops Subcategory

Facilities in the Metal Finishing Job Shops Subcategory must meet the following criteria:

(1) perform one or more of the following 6 operations: electroplating, electroless plating, anodizing,

coating (chromating, phosphating, passivation, and coloring), chemical etching and milling, and printed

circuit board manufacture and (2) own not more than 50 percent (on an annual area basis) of the

materials undergoing metal finishing. EPA is proposing to include printed wiring board job shops in this

subcategory based on the unique economics of job shop operation. 

The Agency estimates that there are approximately 1,500 indirect dischargers and 15

direct dischargers in the proposed Metal Finishing Job Shops Subcategory. EPA currently regulates all

facilities in this subcategory under the existing Metal Finishing or Electroplating effluent guidelines and

standards. EPA is proposing to cover all of these facilities under MP&M. Therefore, facilities subject

to the Metal Finishing Job Shops Subcategory will no longer be covered by the effluent guidelines and

standards in 40 CFR 413 or 40 CFR 433. 

EPA has identified approximately 30,000 facilities that meet the definition of job shop

but do not perform one or more of the six metal finishing operations as defined in 40 CFR 433. EPA

does not consider such job shops to be part of the Metal Finishing Job Shops Subcategory. These

other job shops typically perform assembly, painting, and machining on a contract basis and are likely

to fall in the General Metals or Oily Waste Subcategories. 

6.2.3 Non-Chromium Anodizing Subcategory

Facilities covered under the Non-Chromium Anodizing Subcategory must perform

aluminum anodizing without using chromic acid or dichromate sealants. Anodizing is a surface

conversion operation used to alter the properties of aluminum for better corrosion resistance and heat

transfer. Generally, non-chromium anodizing facilities perform sulfuric acid anodizing; however,

facilities can use other acids, such as oxalic acid, for aluminum anodizing. EPA will cover anodizers that

use chromic acid or dichromate in the General Metals Subcategory or, if they operate as a job shop, in

the Metal Finishing Job Shops Subcategory.

EPA estimates that there are approximately 190 indirect dischargers and, to date, has

not identified any direct dischargers in the Non-Chromium Anodizing Subcategory. The wastewater

generated at non-chromium anodizing facilities contains very low levels of metals (with the exception of

aluminum) and toxic organic pollutants. In addition, EPA determined that compliance with one of the

regulatory options that EPA considered proposing would cause 60 percent of the indirect dischargers in

this subcategory to close. For the reasons discussed in detail in Section 14.0, EPA is proposing to

exclude wastewater from indirect discharging non-chromium anodizing facilities from the MP&M

categorical pretreatment standards. Such facilities will still need to comply with the Metal Finishing (40

CFR 433) pretreatment standards for their non-chromium anodizing wastewater and the general

pretreatment standards at 40 CFR Part 403. 
6.0 - Industry Subcategorization

6-15

Some facilities that could potentially fall into the Non-Chromium Anodizing

Subcategory may also perform other metal surface finishing operations. If these facilities commingle

their wastewater from their non-chromium anodizing operations with wastewater from other surface

finishing operations (e.g., chromic acid anodizing, electroplating, chemical conversion coating) for

treatment, they will not be covered by the Non-Chromium Anodizing Subcategory. Instead, the

General Metals or Metal Finishing Job Shop Subcategories would apply. However, for facilities that

discharge their non-chromium anodizing wastewater separately from their other surface finishing

wastewater, control authorities (e.g., POTWs) and permit writers would apply the appropriate limits to

each discharge. 

6.2.4 Printed Wiring Board Subcategory

The Printed Wiring Board Subcategory will cover wastewater discharges from the

manufacture, maintenance, and repair of printed wiring boards (i.e., circuit boards). This subcategory

does not include job shops that manufacture, maintain, or repair printed wiring boards; EPA is covering

these facilities under the Metal Finishing Job Shops Subcategory, as discussed in Section 6.3.2. EPA

currently regulates all facilities in this subcategory by the existing Metal Finishing or Electroplating

effluent guidelines and standards, but will cover all of these facilities under MP&M. Therefore, facilities

subject to the Printed Wiring Board Subcategory will no longer be covered by the effluent limitations

guidelines and standards in 40 CFR 413 or 40 CFR 433. Printed wiring board facilities perform unique

operations, including applying, developing and stripping of photo resist, lead/tin soldering, and wave

soldering. EPA estimates that there are approximately 620 indirect dischargers and 11 direct

dischargers in the proposed Printed Wiring Board Subcategory. 

6.2.5 Steel Forming and Finishing

Although many facilities may perform MP&M operations with steel, EPA has

established the Steel Forming and Finishing Subcategory for facilities that perform MP&M operations

(listed in Section 4.4) and/or cold forming operations on steel wire, rod, bar, pipe, or tube. This

subcategory does not include facilities that perform those operations on other base materials. In a

separate notice, EPA has proposed to revise the Iron and Steel Manufacturing effluent guidelines. The

proposed revisions to the Iron and Steel regulations exclude those facilities that EPA has determined to

be appropriately regulated by the MP&M rule. EPA based this decision on the information gathered

during the data collection effort for the revision to the Iron and Steel Manufacturing regulations. 

The MP&M Steel Forming and Finishing Subcategory does not cover wastewater

generated from any hot steel forming operations, or from cold forming, electroplating, or continuous hot

dip coating of steel sheet, strip, or plates. As mentioned above, the proposed Iron and Steel

Manufacturing effluent guidelines will cover wastewater from such operations.
6.0 - Industry Subcategorization

6-16

There are approximately 110 indirect dischargers and 43 direct dischargers in the Steel

Forming and Finishing Subcategory. All facilities in this subcategory have permits or other control

mechanisms under the existing Iron and Steel Manufacturing regulation (40 CFR 420). 

EPA is proposing to cover wastewater from these steel forming and finishing

operations, regardless of whether they occur at a stand-alone facility or at a steel manufacturing facility. 

When a steel manufacturing facility performs these MP&M steel forming and finishing operations and

commingles the wastewater for treatment with wastewater from other non-MP&M unit operations,

control authorities and permit writers will need to set limits that account for both the MP&M and the

Iron and Steel regulations. EPA refers to this approach as the combined waste stream formula or the

building block approach. For facilities that choose to discharge their MP&M steel forming and finishing

wastewater separate from their iron and steel wastewater, control authorities and permit writers will

apply the appropriate limits to each discharge.

6.2.6 Oily Wastes Subcategory

EPA has created the Oily Wastes Subcategory as a “catch-all” for MP&M facilities

that discharge only oil-bearing wastewater and that do not fit the applicability of the other MP&M

subcategories. EPA is defining the applicability of this subcategory by the presence of specific unit

operations. Facilities in the Oily Wastes Subcategory must not fit the applicability of the Railroad Line

Maintenance or Shipbuilding Dry Dock Subcategories and must only discharge wastewater from one or

more of the following MP&M unit operations: alkaline cleaning for oil removal, aqueous degreasing,

corrosion preventive coating, floor cleaning, grinding, heat treating, impact deformation, machining,

pressure deformation, solvent degreasing, testing (e.g., hydrostatic, dye penetrant, ultrasonic, magnetic

flux), painting, steam cleaning, and laundering. Facilities in this subcategory are predominantly machine

shops or maintenance and repair shops. EPA has defined “corrosion preventive coating” as the

application of removable oily or organic solutions to protect metal surfaces against corrosive

environments. Corrosion preventive coatings include, but are not limited to: petroleum compounds,

oils, hard dry-film compounds, solvent-cutback petroleum-based compounds, emulsions, waterdisplacing polar compounds, and fingerprint removers and neutralizers. Corrosion preventive coating

does not include electroplating, painting, and chemical conversion coating (including phosphate

conversion coating) operations. Based on EPA’s analytical database for this proposal, EPA believes

that wastewater generated from phosphate conversion coating operations contains high levels of zinc

and manganese.

If a facility discharges wastewater from any of the operations listed above but also

discharges wastewater from other MP&M operations (listed in Section 4.4), it does not meet the

criteria of the Oily Wastes Subcategory. EPA has determined that other MP&M unit operations

generate metal-bearing wastewater or combination metal- and oil-bearing wastewater and require

different treatment technologies (e.g., chemical precipitation). EPA included wastewater from floor

cleaning and testing operations in the Oily Wastes Subcategory after confirming through a review of the
6.0 - Industry Subcategorization

6-17

analytical data that there is little or no metals content in these two streams. This subcategory also

includes municipal and state-owned facilities performing only the listed operations.

Like the General Metals Subcategory, the Oily Wastes Subcategory may include 

facilities from 17 of the 18 MP&M industrial sectors (i.e., all except the printed wiring board sector). 

EPA estimates that there are approximately 28,500 indirect dischargers and 900 direct

dischargers in the Oily Wastes Subcategory. EPA has concluded that less than 1 percent of the

MP&M process wastewater discharged from these facilities in this subcategory is covered by existing

effluent guidelines.

In an effort to relieve administrative burden on POTWs that will implement the MP&M

regulation, EPA is proposing to exclude from the MP&M regulations indirect dischargers that would fall

into the Oily Wastes Subcategory when they discharge less than or equal to 2 MGY of MP&M

process wastewater to the POTW. (See Section 14.0 for a discussion of the low-flow exclusion for

indirect dischargers in the Oily Waste Subcategory.)

6.2.7 Railroad Line Maintenance Subcategory

EPA has developed the Railroad Line Maintenance Subcategory to cover facilities that

perform routine cleaning and light maintenance (mostly consisting of parts replacement) on railroad

engines, cars, car-wheel trucks, and similar parts or machines. More specifically, these facilities

discharge wastewater from only those MP&M unit operations that EPA defines as oily operations (see

Section 6.2.6, above), storm water clean-up (which is not covered by the proposed regulation), and/or

washing of final products. EPA considers “washing of final product” an MP&M “oily” operation for

this subcategory. The Agency reviewed the analytical wastewater sampling data for this waste stream

at railroad line maintenance facilities and determined that there is little or no metal content. However,

for other primarily oily subcategories (oily wastes and shipbuilding dry docks), EPA does not consider

this unit operation an MP&M “oily” operation. Railroad line maintenance facilities are similar to

facilities in the Oily Wastes Subcategory in that they produce oil-bearing wastewater and do not

perform MP&M operations that generate wastewater that requires metals removal treatment

technology. This subcategory does not include railroad manufacturing facilities or railroad overhaul or

heavy maintenance facilities. 

EPA estimates that there are approximately 800 indirect dischargers and 35 direct

dischargers in the Railroad Line Maintenance Subcategory. The wastewater generated at railroad line

maintenance facilities contains very low levels of metals and toxic organic pollutants. EPA is proposing

to exclude wastewater from indirect discharging railroad line maintenance facilities from the MP&M

regulations. (See Section 14.0 for a discussion on the rationale for this exclusion). However, EPA is

proposing to regulate conventional pollutants for direct dischargers in this subcategory. 
6.0 - Industry Subcategorization

6-18

6.2.8 Shipbuilding Dry Dock Subcategory

EPA has created the Shipbuilding Dry Dock Subcategory to specifically cover MP&M

process wastewater generated in or on dry docks and similar structures such as graving docks, building

ways, marine railways, and lift barges at shipbuilding facilities (or shipyards). Shipbuilding facilities use

these structures to maintain, repair, or rebuild existing ships, or perform the final assembly and launching

of new ships (including barges). Shipbuilders use these structures to reach surfaces and parts that

would otherwise be under water. Since dry docks and similar structures include sumps or containment

systems, shipyards can control the discharge of pollutants to surface water. Typical MP&M operations

that occur in dry docks and similar structures include abrasive blasting, hydro blasting, painting,

welding, corrosion preventive coating, floor cleaning, aqueous degreasing, and testing (e.g., hydrostatic

testing). Not all of these unit operations generate wastewater. EPA will also cover wastewater

generated when a shipyard cleans a ship’s hull in a dry dock (or similar structure) to remove marine life

(e.g., barnacles) only in preparation for performing MP&M operations. 

This subcategory will cover only process wastewater generated and discharged from

MP&M operations inside and outside ships (including bilge water) that occur in or on dry docks or

similar structures. The Agency is not including MP&M process wastewater that is generated at other

locations at the shipyard (“on-shore” operations) in this subcategory. EPA expects that wastewater

from these “on-shore” shipbuilding operations (e.g., electroplating, plasma arc cutting) will fall under

either the General Metals or Oily Wastes Subcategories. Also, EPA is not including wastewater

generated onboard ships when they are afloat (i.e., not in dry docks or similar structures). For U.S.

military ships, EPA is in the process of establishing standards under the Uniform National Discharge

Standards (UNDS) pursuant to Section 312(n) of the CWA (See 64 F.R. 25125; May 10, 1999) to

regulate discharges of wastewater generated onboard these ships when they are in U.S. waters and are

afloat (e.g., at a shipyard’s dock).

In addition to MP&M wastewater, EPA identified three other types of water streams in

or on dry docks and similar structures: flooding water, dry dock ballast water, and storm water. 

Flooding water enters and exits the dry dock or similar structure prior to performing any MP&M

operations. For example, in a graving dock, the gates are opened, allowing flooding water in and ships

to float inside the chamber. Then the flooding water is drained, leaving the ship’s exterior exposed so

shipyard employees can repair and maintain the ship’s hull. Dry dock ballast water serves a similar

purpose. It is used to lower (or sink) a floating dry dock so that a ship can float over it. Then the dry

dock ballast water is pumped out, raising the dry dock with the ship on top. Flooding water and dry

dock ballast water do not come into contact with MP&M operations. Finally, since these structures

are located outdoors and are exposed to the elements, storm water may fall in or on the dry dock or

similar structures. 

EPA is proposing to exclude all three of these water streams from the MP&M rule. 

EPA has determined that storm water at these facilities is covered by EPA’s recent Storm Water MultiSector General permit, similar general permits issued by authorized states, and individual storm water
6.0 - Industry Subcategorization

6-19

permits. In general, storm water permits at shipyards include best management practices (BMPS) that

are designed to prevent the contamination of storm water. For example, these practices include

sweeping of areas after completion of abrasive blasting or painting.

EPA estimates that there are six indirect dischargers and six direct dischargers in the

Shipbuilding Dry Dock Subcategory. Many shipbuilders operate multiple dry docks (or similar

structures); this is the number of estimated facilities (not dry docks) that discharge MP&M process

wastewater from dry docks or similar structures. Many shipyards perform only dry MP&M unit

operations in their dry docks (and similar structures) or do not discharge wastewater generated in dry

docks (and similar structures) from MP&M unit operations. Many shipyards prefer to handle this

wastewater as hazardous, and contract haul it offsite due to the possible presence of copper (used as

antifoulant) in paint chips from abrasive blasting operations. EPA has determined that shipyards

currently discharging MP&M wastewater from dry docks have oil/water separation technology in

place, such as dissolved air flotation (DAF).

The wastewater discharged from dry docks and similar structures contains very low

levels of metals and toxic organic pollutants. EPA is proposing to exclude wastewater from indirect

discharging dry docks and similar structures at shipbuilding facilities from the MP&M rule. (See

Section 14.0 for a discussion on the rationale for this exclusion). However, EPA is proposing to

regulate conventional pollutants for direct dischargers in this subcategory.
7.0 - Selection of Pollutant Parameters

7-1

7.0 SELECTION OF POLLUTANT PARAMETERS

EPA conducted a study of MP&M wastewater to determine the presence of priority,

conventional, and nonconventional pollutant parameters. The Agency defines priority pollutant

parameters in Section 307(a)(1) of the CWA. In Table 7-1, EPA lists the 126 specific priority

pollutants listed in 40 CFR Part 423, Appendix A. Section 301(b)(2) of the CWA requires EPA to

regulate priority pollutants if EPA determines them to be present at significant concentrations. 

Section 304(a)(4) of the CWA defines conventional pollutant parameters to be biochemical oxygen

demand, total suspended solids, oil and grease, pH, and fecal coliform. These pollutant parameters are

subject to regulation as specified in Sections 304(a)(4), 304(b)(1)(a), 301(b)(2)(e), and 306 of the

CWA. Nonconventional pollutant parameters are those that are neither priority nor conventional

pollutant parameters. These include nonconventional metal pollutants, nonconventional organic

pollutants, and other nonconventional pollutant parameters. Sections 301(b)(2)(f) and 301(g) of the

CWA give EPA the authority to regulate nonconventional pollutant parameters, as appropriate, based

on technical and economic considerations. 
7.0 - Selection of Pollutant Parameters

7-2

Table 7-1

Priority Pollutant Lista

 1 Acenaphthene

 2 Acrolein

 3 Acrylonitrile

 4 Benzene

 5 Benzidine

 6 Carbon Tetrachloride (Tetrachloromethane)

 7 Chlorobenzene

 8 1,2,4-Trichlorobenzene

 9 Hexachlorobenzene

10 1,2-Dichloroethane

11 1,1,1-Trichloroethane

12 Hexachloroethane

13 1,1-Dichloroethane

14 1,1,2-Trichloroethane

15 1,1,2,2-Tetrachloroethane

16 Chloroethane

17 Removed

18 Bis(2-chloroethyl) Ether

19 2-Chloroethyl Vinyl Ether (mixed)

20 2-Chloronaphthalene

21 2,4,6-Trichlorophenol

22 Parachlorometa Cresol (4-Chloro-3-Methylphenol)

23 Chloroform (Trichloromethane)

24 2-Chlorophenol

25 1,2-Dichlorobenzene

26 1,3-Dichlorobenzene

27 1,4-Dichlorobenzene

28 3,3'-Dichlorobenzidine

29 1,1-Dichloroethylene

30 1,2-Trans-Dichloroethylene

31 2,4-Dichlorophenol

32 1,2-Dichloropropane

33 1,3-Dichloropropylene (Trans-1,3-Dichloropropene)

34 2,4-Dimethylphenol

35 2,4-Dinitrotoluene

36 2,6-Dinitrotoluene

37 1,2-Diphenylhydrazine

38 Ethylbenzene

39 Fluoranthene

40 4-Chlorophenyl Phenyl Ether

41 4-Bromophenyl Phenyl Ether

42 Bis(2-Chloroisopropyl) Ether

43 Bis(2-Chloroethoxy) Methane

44 Methylene Chloride (Dichloromethane)

45 Methyl Chloride (Chloromethane)

46 Methyl Bromide (Bromomethane)

47 Bromoform (Tribromomethane)

48 Dichlorobromomethane (Bromodichloromethane)

49 Removed

50 Removed

51 Chlorodibromomethane (Dibromochloromethane)

52 Hexachlorobutadiene

53 Hexachlorocyclopentadiene

54 Isophorone

55 Naphthalene

56 Nitrobenzene

57 2-Nitrophenol

58 4-Nitrophenol

59 2,4-Dinitrophenol

60 4,6-Dinitro-o-Cresol (Phenol, 2-methyl-4,6-dinitro)

61 N-Nitrosodimethylamine

62 N-Nitrosodiphenylamine

63 N-Nitrosodi-n-propylamine (Di-n-propylnitrosamine)

64 Pentachlorophenol

65 Phenol

 66 Bis(2-ethylhexyl) Phthalate

 67 Butyl Benzyl Phthalate

 68 Di-n-butyl Phthalate

 69 Di-n-octyl Phthalate

 70 Diethyl Phthalate

 71 Dimethyl Phthalate

 72 Benzo(a)anthracene (1,2-Benzanthracene)

 73 Benzo(a)pyrene (3,4-Benzopyrene)

 74 Benzo(b)fluoranthene (3,4-Benzo fluoranthene)

 75 Benzo(k)fluoranthene (11,12-Benzofluoranthene)

 76 Chrysene

 77 Acenaphthylene

 78 Anthracene

 79 Benzo(ghi)perylene (1,12-Benzoperylene)

 80 Fluorene

 81 Phenanthrene

 82 Dibenzo(a,h)anthracene (1,2,5,6-Dibenzanthracene)

 83 Indeno(1,2,3-cd)pyrene (2,3-o-Phenylenepyrene)

 84 Pyrene

 85 Tetrachloroethylene (Tetrachloroethene)

 86 Toluene

 87 Trichloroethylene (Trichloroethene)

 88 Vinyl Chloride (Chloroethylene)

 89 Aldrin

 90 Dieldrin

 91 Chlordane (Technical Mixture & Metabolites)

 92 4,4'-DDT (p,p'-DDT)

 93 4,4'-DDE (p,p'-DDX)

 94 4,4'-DDD (p,p'-TDE)

 95 Alpha-endosulfan

 96 Beta-endosulfan

 97 Endosulfan Sulfate

 98 Endrin

 99 Endrin Aldehyde

100 Heptachlor

101 Heptachlor Epoxide

102 Alpha-BHC

103 Beta-BHC

104 Gamma-BHC (Lindane)

105 Delta-BHC

106 PCB-1242 (Arochlor 1242)

107 PCB-1254 (Arochlor 1254)

108 PCB-1221 (Arochlor 1221)

109 PCB-1232 (Arochlor 1232)

110 PCB-1248 (Arochlor 1248)

111 PCB-1260 (Arochlor 1260)

112 PCB-1016 (Arochlor 1016)

113 Toxaphene

114 Antimony (total)

115 Arsenic (total)

116 Asbestos (fibrous)

117 Beryllium (total)

118 Cadmium (total)

119 Chromium (total)

120 Copper (total)

121 Cyanide (total)

122 Lead (total)

123 Mercury (total)

124 Nickel (total)

125 Selenium (total)

126 Silver (total)

127 Thallium (total)

128 Zinc (total)

129 2,3,7,8-Tetrachloro-dibenzo-p-Dioxin (TCDD)

Source: 40 CFR Part 423, Appendix A.

aPriority pollutants are numbered 1 through 129 but include 126 pollutants since EPA removed three pollutants from

the list (Numbers 17, 49, and 50).
7.0 - Selection of Pollutant Parameters

7-3

EPA considered 302 metal and organic pollutant parameters listed in The 1990

Industrial Technology Division List of Analytes (1) for potential regulation under the MP&M proposed

rule. The Agency also considered 22 conventional and other nonconventional pollutant parameters for

potential regulation under the MP&M proposal. These 327 pollutant parameters of which the Agency

measured in the MP&M sampling program are identified in Section 3.0.

The Agency did not consider fecal coliform, a conventional pollutant parameter, for

regulation under the MP&M rule; therefore, it is not included in the 327 pollutant parameters discussed

above. The presence of fecal coliform bacteria, a microorganism that resides in the intestinal tract of

humans and other warm-blooded animals, indicates that wastewater has been contaminated with feces

from humans or other warm-blooded animals. EPA does not expect fecal coliform to be present in

process wastewater from MP&M sites because sanitary wastewater is discharged separately from

process wastewater. 

Section 7.1 discusses the criteria used to identify pollutant parameters of concern (i.e.,

considered for regulation) under the MP&M proposed rule. Sections 7.2 and 7.3 present the criteria

used to select pollutant parameters for regulation for direct and indirect dischargers, respectively. 

Section 7.4 lists the references used in this chapter.

7.1 Identification of Pollutant Parameters of Concern

EPA analyzed for the 327 pollutant parameters discussed above in over 1,932 samples

of wastewater collected during the MP&M sampling program described in Section 3.0. Of these

samples, EPA collected 727 from unit operation wastewater, 693 from influent-to-treatment

wastewater, and 684 from effluent-from-treatment wastewater. The Agency notes that a number of

these samples fit into more than one category: EPA classified 20 unit operations as influents-totreatment and 152 influents-to-treatment for one technology as effluents-from-treatment for a second

technology. EPA reduced the list of 324 pollutants to 132 pollutants (referred to as pollutants of

concern or POCs) for further consideration by retaining only those pollutants that met the following

criteria: 

C EPA detected the pollutant parameter in at least three samples collected during

the MP&M sampling program.

C The average concentration of the pollutant parameter in samples of wastewater

from MP&M unit operations and influents-to-treatment was at least five times

the minimum level (ML) or the average concentration of effluent-from-treatment

wastewater samples exceeded five times the minimum level. EPA describes the

ML as “the lowest level at which the entire analytical system must give a

recognizable signal and an acceptable calibration point for the analyte” (2).
7.0 - Selection of Pollutant Parameters

7-4

C EPA analyzed the pollutant parameter in a quantitative manner following the

appropriate quality assurance/quality control (QA/QC) procedures. To meet

this criteria, the Agency excluded wastewater analyses performed solely for

certain semi-quantitative “screening” purposes. EPA performed these semiquantitative analyses only in unusual cases (e.g. to qualitatively screen for the

presence of a rare metal such as osmium). 

For the first criterion, EPA used data from the unit operation, influent-to-treatment, and

effluent-from-treatment wastewater samples to determine the total number of detected samples for each

pollutant parameter. EPA calculated the average pollutant concentrations from the unit operation and

influent-to-treatment wastewater samples to determine if the data met the second criterion. Separately,

EPA also included effluent-from-treatment wastewater pollutant concentrations in this assessment, and

the following pollutants passed the second criterion: 1,1-dichloroethene, chloroform, diphenyl ether,

isophorone, n-nitrosopiperidine, and trichlorofluoromethane. Because these pollutants have

concentrations exceeding five times the ML in the effluent streams, EPA considered them pollutants of

concern. Of the 324 pollutant parameters initially considered by the Agency for potential regulation

under MP&M, EPA excluded 192 as pollutant parameters of concern for the following reasons:

C EPA did not detect one hundred and thirteen (113) pollutant parameters in

samples collected during the MP&M sampling program. Table 7-2 lists these

pollutant parameters. 

C EPA detected fifty (50) in less than three samples collected during the MP&M

sampling program. Table 7-3 lists these pollutant parameters. 

C EPA detected thirty (30) pollutant parameters at average concentrations that

were less than five times the ML in unit operations and influent-to-treatment or

did not have a detection limit (acidity, total alkalinity, and pH). Table 7-4 lists

these pollutant parameters. 

C EPA did not analyze five of the remaining pollutants (strontium, potassium,

sulfur, silicon, and phosphorus) in a quantitative manner. Rather, EPA

performed analyses for these pollutants using semi-quantitative methods for

“screening” purposes to determine if these analytes were present. Therefore,

the Agency did not subject these analytes to the QA/QC procedures required

by analytical method 1620. Based on the screening results, the Agency

performed a full quantitative analysis for gold, palladium, platinum, and

rhodium. 
7.0 - Selection of Pollutant Parameters

7-5

Table 7-2

Pollutant Parameters Not Detected in Any Samples Collected During the

MP&M Sampling Program

Priority Pollutant Parameters

 1,2-Dichloropropane Benzo(K)Fluoranthene

 1,3-Dichlorobenzene Bis(2-Chloroisopropyl) Ether

 2-Chloroethylvinyl Ether Chrysene

 3,3'-Dichlorobenzidine Dibenzo(A,H)Anthracene

 4-Bromophenyl Phenyl Ether Hexachlorobenzene

 4-Chlorophenylphenyl Ether Hexachlorobutadiene

 Acenaphthylene Hexachlorocyclopentadiene 

 Benzidine Hexachloroethane

 Benzo(A)Anthracene Indeno(1,2,3-Cd)Pyrene

 Benzo(A)Pyrene Pentachlorophenol

 Benzo(B)Fluoranthene Trans-1,2-Dichloroethene

 Benzo(Ghi)Perylene Trans-1,3-Dichloropropene

Nonconventional Organic Pollutant Parameters

 1,2,3-Trichlorobenzene Aniline, 2,4,5-Trimethyl-

 1,2,3-Trichloropropane Aramite

 1,2,3-Trimethoxybenzene Benzanthrone

 1,2,4,5-Tetrachlorobenzene Benzenethiol

 1,2-Dibromo-3-Chloropropane Biphenyl, 4-Nitro

 1,2-Dibromoethane Chloroacetonitrile

 1,3-Butadiene, 2-Chloro Crotonaldehyde

 1,3-Dichloro-2-Propanol Crotoxyphos

 1,3-Dichloropropane Diethyl Ether

 1,5-Naphthalenediamine Dimethyl Sulfone

 1-Chloro-3-Nitrobenzene Diphenyldisulfide

 1-Phenylnaphthalene Ethyl Cyanide

 2,3,4,6-Tetrachlorophenol Ethyl Methacrylate

 2,3,6-Trichlorophenol Ethyl Methanesulfonate

 2,3-Benzofluorene Hexachloropropene

 2,3-Dichloroaniline Iodomethane

 2,3-Dichloronitrobenzene Isosafrole

 2,4,5-Trichlorophenol Longifolene

 2,6-Dichloro-4-Nitroaniline Malachite Green

 2,6-Dichlorophenol Mestranol

 2-Methylbenzothioazole Methapyrilene

 2-Nitroaniline Methyl Methanesulfonate

 2-Phenylnaphthalene n-Nitrosodiethylamine
Table 7-2 (Continued)

7.0 - Selection of Pollutant Parameters

7-6

Nonconventional Organic Pollutant Parameters (continued)

 2-Propen-1-Ol o-Toluidine, 5-Chloro-

 2-Propenenitrile, 2-Methyl- p-Dimethylaminoazobenzene

 3,3'-Dimethoxybenzidine Pentachlorobenzene

 3,5-Dibromo 4-Hydroxybenzonitrile Pentachloroethane

 3-Chloropropene Perylene

 3-Methylcholanthrene Phenacetin

 3-Nitroaniline Pronamide

 4,4'-Methylenebis(2-Chloroaniline) Squalene

 4,5-Methylene Phenanthrene Thioacetamide

 4-Chloro-2-Nitroaniline Trans-1,4-Dichloro-2-Butene

 5-Nitro-O-Toluidine Triphenylene

 7,12-Dimethylbenz(A)Anthracene Vinyl Acetate

Nonconventional Metal Pollutant Parameters

 Cerium Praseodymium

 Erbium Rhenium

 Europium Samarium

 Gadolinium Scandium

 Gallium Tellurium

 Germanium Terbium

 Holmium Thorium

 Indium Thulium

 Iodine Uranium

 Lanthanum

Source: MP&M sampling data.
7.0 - Selection of Pollutant Parameters

7-7

Table 7-3

Pollutant Parameters Detected in Less Than Three Samples Collected

During the MP&M Sampling Program

Priority Pollutant Parameters

 1,1,2,2-Tetrachloroethane 2-Chloronaphthalene

 1,1,2-Trichloroethane 2-Chlorophenol

 1,2,4-Trichlorobenzene Acrylonitrile

 1,2-Dichlorobenzene Bis(2-Chloroethoxy)Methane

 1,2-Dichloroethane Bis(2-Chloroethyl) Ether

 1,2-Diphenylhydrazine Bromomethane

 1,4-Dichlorobenzene Nitrobenzene

 2,4-Dichlorophenol n-Nitrosodi-n-Propylamine

 2,4-Dinitrotoluene Vinyl Chloride

Nonconventional Organic Pollutant Parameters

 1,1,1,2-Tetrachloroethane Ethylenethiourea

 1,2:3,4-Diepoxybutane n-Nitrosodi-n-Butylamine

 1,3,5-Trithiane n-Nitrosomethylphenylamine

 1,4-Dinitrobenzene o-Anisidine

 1,4-Naphthoquinone p-Chloroaniline

 1-Naphthylamine Pentamethylbenzene

 2,6-Di-Tert-Butyl-P-Benzoquinone Phenothiazine

 2-Picoline p-Nitroaniline

 4-Aminobiphenyl Resorcinol

 Beta-Naphthylamine Safrole

 Carbazole Thianaphthene

 Cis-1,3-Dichloropropene Thioxanthe-9-One

 Dibromomethane Toluene, 2,4-DiaminoNonconventional Metal Pollutant Parameters

 Dysprosium Rhodium

 Hafnium Ruthenium

 Neodymium Zirconium

Source: MP&M sampling data.
7.0 - Selection of Pollutant Parameters

7-8

Table 7-4

Pollutant Parameters Detected at Average Concentrations of Less Than

Five Times the Minimum Level During the MP&M Sampling Program

Priority Pollutant Parameters

 2,4,6-Trichlorophenol Chloroform

 4,6-Dinitro-o-Cresol Chloromethane

 Benzene Dibromochloromethane

 Bromodichloromethane Diethyl Phthalate

 Carbon Tetrachloride (Tetrachloromethane) Tribromomethane

Nonconventional Organic Pollutant Parameters

 2-(Methylthio)Benzothiazole n-Nitrosopiperidine

 Diphenyl Ether o-Toluidine

 n-Nitrosomethylethylamine Trichlorofluoromethane

 n-Nitrosomorpholine

Nonconventional Metal Pollutant Parameters

 Bismuth Osmium

 Iridium Palladium

 Lithium Tantalum

 Lutetium Tungsten

 Niobium Ytterbium

Source: MP&M sampling data.

After excluding these pollutants, EPA defines the 132 remaining pollutants as pollutant

parameters of concern (POCs). These include 48 priority pollutant parameters (34 priority organic

pollutants, 13 priority metal pollutants, and cyanide), 3 conventional pollutant parameters, and 81

nonconventional pollutant parameters (50 organic pollutants, 15 metal pollutants, and 16 other

nonconventional pollutants). These pollutant parameters, along with the number of times EPA analyzed

and detected each pollutant parameter in the influent or in unit operations and the corresponding

average concentration (excluding nondetected pollutants), are shown in Table 7-5.
7.0 - Selection of Pollutant Parameters

7-9

Table 7-5

Pollutant Parameters Selected for Further

Consideration Under the MP&M Proposed Rule

Pollutant Parameter

No. of Times

Analyzed for All

Samples

No. of Times

Detected for All

Samples

Average Concentration

in Samples from Unit

Operations and

Treatment Influents

(mg/L)

 Priority Organic Pollutants

 1,1,1-Trichloroethane 1043 28 0.327

 1,1-Dichloroethane 1043 7 0.091

 1,1-Dichloroethylene 1043 3 0.418

 2,4-Dimethylphenol 994 31 0.078

 2,4-Dinitrophenol 946 4 83.7

 2,6-Dinitrotoluene 1029 3 2.73

 2-Nitrophenol 1021 9 0.394

 4-Chloro-m-cresol 1003 95 260

 4-Nitrophenol 969 5 2.99

 Acenaphthene 1029 6 0.332

 Acrolein 1003 5 0.307

 Anthracene 1029 4 0.117

 Bis(2-Ethylhexyl) Phthalate 1028 211 4.15

 Benzyl Butyl Phthalate 1026 16 1.08

 Chlorobenzene 1043 7 0.282

 Chloroethane 1043 4 4.22

 Chloroform 1043 331 0.049

 Di-N-Butyl Phthalate 1026 41 0.352

 Di-N-Octyl Phthalate 1028 18 1.58

 Dimethyl Phthalate 994 3 0.739

 Ethylbenzene 1043 61 0.165

 Fluoranthene 1028 4 0.132

 Fluorene 1029 18 0.956

 Isophorone 996 3 0*

 Methylene Chloride 1043 52 0.403

 n-Nitrosodimethylamine 996 3 3.68

 N-Nitrosodiphenylamine 1029 15 1.14

 Naphthalene 1029 71 0.638

 Phenanthrene 1029 45 0.500

 Phenol 1021 244 10.1

 Pyrene 1028 5 0.219 
Table 7-5 (Continued)

7.0 - Selection of Pollutant Parameters

Pollutant Parameter

No. of Times

Analyzed for All

Samples

No. of Times

Detected for All

Samples

Average Concentration

in Samples from Unit

Operations and

Treatment Influents

(mg/L)

7-10

 Tetrachloroethene 1043 23 0.210

 Priority Organic Pollutants (continued)

 Toluene 1043 83 0.230

 Trichloroethylene 1042 40 0.092

 Priority Metal Pollutants

 Antimony 1956 606 6.12

 Arsenic 1972 627 0.178

 Beryllium 1972 301 0.147

 Cadmium 1972 873 244

 Chromium 1972 1480 1,029

 Copper 1972 1752 495

 Cyanide 406 327 2,072

 Lead 1972 911 30.0

 Mercury 1970 321 0.0014

 Nickel 1972 1518 356

 Selenium 1956 317 0.137

 Silver 1972 698 0.531

 Thallium 1956 206 0.065

 Zinc 1971 1691 188

 Conventional Pollutants

 BOD 5-Day (Carbonaceous) 1005 757 2,015

 Oil And Grease (As HEM) 1028 554 2,308

 Total Suspended Solids 1959 1563 1,007

 Nonconventional Organic Pollutants

 1,4-Dioxane 1003 33 0.854

 1-Bromo-2-Chlorobenzene 989 8 0.233

 1-Bromo-3-Chlorobenzene 989 6 0.135

 1-Methylfluorene 989 24 0.347

 1-Methylphenanthrene 989 29 0.581

 2-Butanone 1003 160 1.59

 2-Hexanone 1003 7 1.26

 2-Isopropylnaphthalene 989 6 3.21

 2-Methylnaphthalene 989 61 0.775

 2-Propanone 1003 593 3.14

 3,6-Dimethylphenanthrene 989 13 1.24

 4-Methyl-2-Pentanone 1003 91 5.19

 Acetophenone 989 10 0.159
Table 7-5 (Continued)

7.0 - Selection of Pollutant Parameters

Pollutant Parameter

No. of Times

Analyzed for All

Samples

No. of Times

Detected for All

Samples

Average Concentration

in Samples from Unit

Operations and

Treatment Influents

(mg/L)

7-11

 Alpha-Terpineol 978 133 13.6

 Nonconventional Organic Pollutants (continued)

 Aniline 989 19 0.684

 Benzoic Acid 989 202 277

 Benzyl Alcohol 989 61 1.23

 Biphenyl 989 23 0.174

 Carbon Disulfide 1003 63 0.408

 Dibenzofuran 989 4 0.055

 Dibenzothiophene 988 6 0.240

 Diphenyl Ether 989 5 0.047

 Diphenylamine 989 14 0.704

 Hexanoic Acid 989 237 15.2

 Isobutyl Alcohol 1003 19 0.167

 m+p Xylene 595 31 0.159

 m-Xylene 408 21 0.498

 Methyl Methacrylate 1003 6 0.396

 n,n-Dimethylformamide 989 63 0.193

 n-Decane 989 67 2.10

 n-Docosane 989 108 3.47

 n-Dodecane 989 125 13.8

 n-Eicosane 988 156 3.30

 n-Hexacosane 989 95 5.84

 n-Hexadecane 989 168 6.27

 n-Nitrosopiperidine 989 4 0.020

 n-Octacosane 989 40 7.45

 n-Octadecane 989 174 5.74

 n-Tetracosane 988 90 4.13

 n-Tetradecane 989 158 12.7

 n-Triacontane 988 55 2.69

 o+p Xylene 408 30 0.256

 o-Cresol 989 16 0.067

 o-Xylene 595 40 0.058

 p-Cresol 989 82 0.293

 p-Cymene 989 21 0.988

 Pyridine 989 37 0.920

 Styrene 989 9 0.261

 Trichlorofluoromethane 1043 12 0.049
Table 7-5 (Continued)

7.0 - Selection of Pollutant Parameters

Pollutant Parameter

No. of Times

Analyzed for All

Samples

No. of Times

Detected for All

Samples

Average Concentration

in Samples from Unit

Operations and

Treatment Influents

(mg/L)

7-12

 Tripropyleneglycol Methyl Ether 989 141 190

 Nonconventional Metal Pollutants

 Aluminum 1972 1520 166

 Barium 1972 1651 1.75

 Boron 1913 1645 85.0

 Calcium 1972 1929 68.4

 Cobalt 1972 640 12.8

 Gold 161 104 16.2

 Iron 1972 1743 777

 Magnesium 1972 1803 53.8

 Manganese 1972 1620 43.4

 Molybdenum 1972 1091 2.97

 Sodium 1972 1953 3,384

 Tin 1912 850 153

 Titanium 1913 949 32.6

 Vanadium 1972 504 5.31

 Yttrium 1913 306 0.061

 Other Nonconventional Pollutants

 Amenable Cyanide 160 128 44.3

 Ammonia As Nitrogen 689 569 385

 Chemical Oxygen Demand (COD) 1461 1343 11,289

 Chloride 677 631 5,526

 Fluoride 688 618 301

 Hexavalent Chromium 1074 268 1.78

 Sulfate 1171 1086 7,046

 Total Dissolved Solids 1953 1948 21,883

 Total Kjeldahl Nitrogen 661 572 606

 Total Organic Carbon (TOC) 997 838 3,385

 Total Petroleum Hydrocarbons (As SGT-HEM) 1016 350 841

 Total Phosphorus 500 452 170

 Total Recoverable Phenolics 1357 871 11.7

 Total Sulfide 215 80 6.50

 Weak-Acid Dissociable Cyanide 72 62 19.4

 Ziram 31 22 1.41

Source: MP&M sampling data.
7.0 - Selection of Pollutant Parameters

7-13

7.2 Pollutants Proposed to be Regulated for Direct Dischargers

EPA developed the list of pollutants to be regulated for each of the MP&M

subcategories from the pollutants of concern list discussed above. As a first step in the selection of

regulated pollutants, the Agency grouped the MP&M subcategories (discussed in Section 6) according

to whether the facilities in the subcategory generated wastewater with high metals content (metalbearing) or wastewater with low concentration of metals and high oil and grease content (oil-bearing). 

EPA determined that the following subcategories generate metal-bearing wastewater: General Metals,

Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Board, and Steel Forming and

Finishing. For the remainder of the subcategories (Oily Wastes, Railroad Line Maintenance, and

Shipbuilding Dry Docks), the Agency determined that they generate oil-bearing wastewater. For both

of these groups, the Agency analyzed the concentrations and prevalence of the pollutants of concern

from unit operations, unit operation rinses, and influent to treatment systems in order to determine which

POCs EPA could eliminate from its list of pollutants considered for regulation. The tables in Section 5

summarize the data that EPA considered in determining the pollutants selected for regulation. 

EPA considered the following factors in determining which POCs should be eliminated

from the potential list of regulated pollutants:

C The pollutant is controlled through the regulation of other pollutants.

C The pollutant is present in only trace amounts in the subcategory and/or is not

likely to cause toxic effects.

C The pollutant may serve as a treatment chemical.

C The pollutant is not controlled by the selected BPT/BAT technology.

7.2.1 Regulated Pollutant Analysis for Direct Dischargers in the Metal-Bearing

Subcategories

As mentioned in Section 7.2, EPA determined that the following subcategories generate

metal-bearing wastewater: General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing,

Printed Wiring Board, and Steel Forming and Finishing. This section describes EPA’s proposed

regulated pollutant selection criteria for direct dischargers in the metal-bearing subcategories. 

EPA did not select the 42 pollutants of concern present in Table 7-6 because they are

controlled through the regulation of other pollutants in the metal-bearing subcategories.
7.0 - Selection of Pollutant Parameters

7-14

Table 7-6

Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Controlled Through the Regulation of

Other Pollutants

Conventional Pollutant

 BOD5

Other Nonconventional Pollutant

COD Total Recoverable Phenolics

 Hexavalent Chromium Weak-Acid Dissociable Cyanide

 Total Petroleum Hydrocarbons (as SGT-HEM)

Nonconventional Organic Pollutants

 1,4-Dioxane n-Decane

 1-Bromo-2-Chlorobenzene n-Docosane

 1-Bromo-3-Chlorobenzene n-Dodecane

 2-Butanone n-Eicosane

 2-Hexanone n-Hexacosane

 2-Propanone n-Nitrosopiperidine

 4-Methyl-2-Pentanone n-Octacosane

 Acetophenone n-Octadecane

 Alpha-Terpineol n-Tetracosane

 Benzyl Alcohol n-Triacontane

 Diphenyl Ether o+p Xylene

 Diphenylamine o-Cresol

 Hexanoic Acid o-Xylene

 Isobutyl Alcohol p-Cresol

 m+p Xylene Pyridine

 m-Xylene Styrene

 Methyl Methacrylate Trichlorofluoromethane

 n,n-Dimethylformamide Tripropylenenglycol Methyl Ether

BOD5 and COD are methods for measuring the oxygen demand of wastewater. EPA

is proposing a limit for Total Organic Carbon (TOC), an alternate method that measures all oxidizable

organic material in a waste stream, including some organic chemicals not oxidized (and, therefore not

detected) in the BOD5 and COD tests. EPA chose TOC as an indicator parameter because of its

ability to measure all types of organic pollutants and because it found TOC to be the best general

indicator parameter for measuring the sum of organic compounds in an MP&M waste stream. EPA is

not proposing a limit for hexavalent chromium because it has selected total chromium for regulation. 

Weak-acid dissociable cyanide will be controlled through the regulation of total cyanide (or amenable
7.0 - Selection of Pollutant Parameters

7-15

cyanide). EPA did not propose a limit for Total Petroleum Hydrocarbons (TPH) (as SGT-HEM)

because it believes that the regulation of oil and grease (O&G) and EPA’s proposed organics control

options will control the discharge of TPH (as SGT-HEM). The parameter Total Recoverable

Phenolics will be controlled through the regulation of the Total Organics Parameter (TOP) which

includes compounds such as phenol. EPA also believes that the list of 36 nonconventional organic

compounds listed in the table above will be controlled through the regulation of TOP. The organic

parameters that comprise the TOP are explained in more detail later in this section. 

EPA determined that it was not necessary to propose limits for the 12 metals listed in

Table 7-7 because it detected these metals at low levels in its sampling of MP&M wastewater. As

shown in Table 5-14, the median concentration at the influent to treatment for all of these metals was

less than 0.1 mg/L. EPA also decided not to propose a limit for fluoride because the Agency did not

detect fluoride at concentrations that would cause toxic effects. As shown in Table 5-14, the median

concentration of fluoride at the influent to treatment was 1.55 mg/L. This value is below EPA’s primary

drinking water standard for fluoride (the maximum contaminant level (MCL)) which is 4 mg/L. 

Table 7-7

Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Present in Only Trace Amounts and/or

Are Not Likely to Cause Toxic Effects

Priority Metals

 Antimony Mercury

 Arsenic Selenium

 Beryllium Thallium

Nonconventional Metals

 Barium Titanium

 Cobalt Vanadium

 Gold Yttrium

Other Nonconventional Pollutant

 Fluoride

EPA did not select the 8 pollutants of concern presented in Table 7-8 for proposed

regulation in the metal-bearing subcategories because they may be used as treatment chemicals in the

MP&M industry.
7.0 - Selection of Pollutant Parameters

7-16

Table 7-8

Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They May Serve as Treatment Chemicals in the

MP&M Industry

Nonconventional Metals

 Aluminum Magnesium

 Calcium Sodium

 Iron

Other Nonconventional Pollutants

 Sulfate Ziram

 Chloride

EPA eliminated the nonconventional metals listed in Table 7-8 plus sulfate and chloride

from consideration because regulation of these pollutants could interfere with their beneficial use as

wastewater treatment additives. In the case of ziram, EPA detected this pollutant at MP&M facilities

that use sodium dimethyldithiocarbamate (DTC) as a reducing and precipitating agent in the treatment

of complexed or chelated metals. For the MP&M proposal, EPA based the estimated costs and

pollutant removals associated with the treatment of chelated or complexed metals on the use of DTC. 

When DTC is used appropriately, it may effectively enhance the removal of some difficult to treat

pollutants without impacting the environment or POTW operations. However, DTC is toxic to aquatic

life and to activated sludge and thus can upset POTW operations. DTC can combine to form, or break

down to, a number of other toxic chemicals, including thiram and ziram (both EPA registered

fungicides) and other thiurams, other dithiocarbamates, carbon disulfide, and dimethylamine. Ziram is

known to be toxic to aquatic life at the following levels: LC 50 less than 10 ug/L (parts per billion) for

several varieties of bluegill and trout; LC 50 between 10 and 100 ug/L in other studies (see AQUIRE

database at http://www.epa.gov/medecotx/quicksearch.htm). EPA solicits comment in the proposal on

the use of DTC for the treatment of chelated wastewater and its potential harmful effects on the

environment and on POTW operations. As explained in the proposed rule, the Agency is particularly

interested in receiving data and information on alternative treatments for wastewater containing chelated

or complexed metals.

EPA did not select the 5 pollutants of concern presented in Table 7-9 for proposed

regulation in the metal-bearing subcategories because they are not controlled by the selected BPT/BAT

technology. EPA’s analytical data showed that the proposed BPT/BAT treatment option did not

effectively remove the low levels of ammonia as nitrogen or the low levels of Total Kjeldahl Nitrogen

present in MP&M wastewater. As shown in Table 5-14, the median ammonia concentration at the

influent to treatment was only 2.56 mg/L and treatment systems sampled by EPA achieved on average

less than 20 percent removal. Similarly, the proposed BPT/BAT treatment systems sampled by EPA
7.0 - Selection of Pollutant Parameters

7-17

did not demonstrate effective removal of boron, total phosphorous, or Total Dissolved Solids and only

demonstrated incidental removal of boron. 

Table 7-9

Pollutants Not Selected for Proposed Regulation for the Metal-Bearing

Subcategories Because They Are Not Controlled by the Selected BPT/BAT

Technology 

Other Nonconventional Pollutants

 Ammonia as Nitrogen Total Kjeldahl Nitrogen

 Total Dissolved Solids Total Phosphorous

Nonconventional Metal Pollutant

 Boron

EPA considered proposing limits for all of the priority and nonconventional organic

pollutants listed in Table 7-10; however, due to the variety of organic pollutants used across MP&M

facilities, EPA determined that it would be burdensome to facilities and permit writers/control authorities

have to determine which limits to apply to a facility. Instead, EPA is proposing an approach similar to

the one used in the Metal Finishing Effluent Guidelines (40 CFR Part 433). EPA developed a list of

organic pollutants, called the Total Organics Parameter (TOP), using the list of organic priority

pollutants and other nonconventional organic pollutants that met EPA's pollutant of concern criteria for

this rule. Of the nonconventional organic chemicals on the MP&M pollutant of concern list, EPA

included only those that were removed in appreciable quantities by the selected technology option

(based on toxic weighted pound-equivalents) in two or more subcategories. The TOP list is comprised

of all of the priority and nonconventional organic pollutants listed in Table 7-10. 
7.0 - Selection of Pollutant Parameters

7-18

Table 7-10

64 Remaining Pollutants Considered for Proposed Regulation for the MetalBearing Subcategories

Priority Metals

 Cadmium Lead

 Chromium Nickel

 Copper Silver

 Cyanide Zinc

Nonconventional Metals

 Manganese Tin

 Molybdenum

Conventional Pollutants

 Oil and Grease (as HEM) Total Suspended Solids

Other Nonconventional Pollutants

 Amenable Cyanide Total Sulfide

 Total Organic Carbon

Priority Organic Pollutants

 1,1,1-Trichloroethane Di-n-Butyl Phthalate

 1,1-Dichloroethane Di-n-Octyl Phthalate

 1,1-Dichloroethylene Dimethyl Phthalate

 2,4-Dimethylphenol Ethylbenzene

 2,4-Dinitrophenol Fluoranthene

 2,6-Dinitrotoluene Fluorene

 2-Nitrophenol Isophorone

 4-Chloro-m-cresol Methylene Chloride

 4-Nitrophenol n-Nitrosodimethylamine

 Acenaphthene n-Nitrosodiphenylamine

 Acrolein Naphthalene

 Anthracene Phenanthrene

 Benzyl Butyl Phthalate Phenol

 Bis(2-Ethylhexyl) Phthalate Pyrene

 Chlorobenzene Tetrachloroethene

 Chloroethane Toluene

 Chloroform Trichloroethylene

 1-Methylfluorene Biphenyl

 1-Methylphenanthrene Carbon Disulfide

 2-Isopropylnaphthalene Dibenzofuran

 2-Methylnaphthalene Dibenzothiophene
Table 7-10 (Continued)

7.0 - Selection of Pollutant Parameters

7-19

Nonconventional Organic Pollutants

 3,6-Dimethylphenanthrene n-Hexadecane

 Aniline n-Tetradecane

 Benzoic Acid p-Cymene

EPA has derived the numerical limit for TOP based on the contribution of each of the

organic pollutants listed in Table 7-10 using the data collected during sampling and determined the

limitation using the same statistical methodology used for other limits developed for this proposal (see

Table 10-7 for the list of TOP pollutants). In any case where the data for these pollutants indicated a

level below the minimum level (ML) (i.e., below quantitation), EPA used the ML for the specific

pollutant in the summation of the TOP limit. Facilities will only have to monitor for those TOP

chemicals that are reasonably present (see Section 15.2.6 for a discussion on monitoring waivers). 

Note that the TOP limit shall not be adjusted for those pollutants that are not reasonably present. In the

proposal, EPA solicits comment on this methodology. 

As discussed above, EPA is also proposing to allow the use of an indicator parameter

to measure the presence of organic pollutants in MP&M process wastewater. Facilities can monitor

for the organic pollutants specified in the TOP list to demonstrate compliance with the TOP limit or they

can monitor for Total Organic Carbon (TOC) and meet the TOC limit. 

Finally, EPA is proposing a third alternative to reduce monitoring burden – the use of an

organic pollutant management plan. The organic pollutant management plan would need to specify the

following, to the satisfaction of the permitting authority or control authority:

C The toxic and non-conventional organic constituents used at the facility;

C The disposal method used; 

C The procedures in place for ensuring that organic pollutants do not routinely

spill or leak into the wastewater or that minimize the amount of organic

pollutants used in the process; 

C The procedures in place to manage the oxidation reduction potential (ORP)

during cyanide destruction to control the formation of chlorinated organic

byproducts; and

C The procedures to prevent the over dosage of dithiocarbamates when treating

chelated wastewater. 
7.0 - Selection of Pollutant Parameters

7-20

Facilities choosing to develop an organic pollutant management plan would need to

certify that the procedures described in the plan are being implemented at the facility. Section 15.2.6

explains the organic management plan in greater detail. 

In order to determine the pollutants proposed for regulation for each of the metalbearing subcategories, EPA considered each of the remaining pollutants in Table 7-10 on a

subcategory-by-subcategory basis. That is, after eliminating the pollutants listed in Tables 7-6 through

7-9 by analyzing all of the data for the metal-bearing subcategories combined, EPA then considered

only data from each individual subcategory in order to determine the proposed regulated pollutants for

each subcategory. 

7.2.1.1 General Metals Subcategory 

For the direct dischargers in the General Metals subcategory, EPA proposed

regulations for all of the pollutants listed in Table 7-10. For the organic parameters listed in Table 7-9,

facilities in this subcategory may choose from the following three options in order to comply with the

regulation: comply with the limit for TOC; comply with the limit for TOP; or implement an organic

pollutant management plan. Section 14 lists the effluent limitations for direct dischargers in the General

Metals subcategory.

7.2.1.2 Metal Finishing Job Shops Subcategory

For the direct dischargers in the Metal Finishing Job Shops subcategory, EPA

proposed regulations for all of the pollutants listed in Table 7-10. For the organic parameters listed in

Table 7-10, facilities in this subcategory may choose from the following three options in order to

comply with the regulation: comply with the limit for TOC; comply with the limit for TOP; or implement

an organic pollutant management plan. Section 14 lists the effluent limitations for direct dischargers in

the Metal Finishing Job Shops subcategory.

7.2.1.3 Non-Chromium Anodizing Subcategory

For the direct dischargers in the Non-Chromium Anodizing subcategory, EPA

proposed regulations for TSS, O&G, aluminum, manganese, nickel, and zinc. Although EPA had

eliminated aluminum from consideration for regulation for the metal-bearing subcategories because of its

use as a treatment chemical, EPA decided to propose limits for aluminum for direct dischargers in this

subcategory because of the large amount of aluminum discharged by non-chromium anodizing facilities. 

(See Section 6.6.3 for a description of the Non-Chromium Anodizing subcategory.) EPA also

determined that unit operations performed at non-chromium anodizing facilities may generate

wastewater containing significant quantities of manganese, nickel, and zinc and is proposing effluent

limitations for these three metals. The Agency did not identify a large number of organic pollutants in

wastewater from non-chromium anodizing operations and therefore did not propose a TOC or TOP

limit for these dischargers. It did, however, propose a limit for O&G to control the discharge of this
7.0 - Selection of Pollutant Parameters

7-21

pollutant into surface water. Section 14 lists the effluent limitations for direct dischargers in the NonChromium Anodizing subcategory.

7.2.1.4 Printed Wiring Board Subcategory

For the direct dischargers in the Printed Wiring Board subcategory, EPA is proposing

regulations for all of the pollutants listed in Table 7-10 except cadmium, molybdenum and silver. These

three metals were not found at significant concentrations at facilities in the this subcategory. For the

organic parameters listed in Table 7-10, facilities in the Printed Wiring Board subcategory may choose

from the following three options in order to comply with the regulation: comply with the limit for TOC;

comply with the limit for TOP; or implement an organic pollutant management plan. Section 14 lists the

effluent limitations for direct dischargers in the Printed Wiring Board subcategory.

7.2.1.5 Steel Forming and Finishing Subcategory

For the direct dischargers in the Steel Forming and Finishing subcategory, EPA

proposed regulations for all of the pollutants listed in Table 7-10. For the organic parameters listed in

Table 7-10, facilities in this subcategory may choose from the following three options in order to

comply with the regulation: comply with the limit for TOC; comply with the limit for TOP; or implement

an organic pollutant management plan. Section 14 lists the effluent limitations for direct dischargers in

the Steel Forming and Finishing subcategory.

7.2.2 Regulated Pollutant Analysis for Direct Dischargers in the Oil-Bearing

Subcategories

As mentioned in Section 7.2, EPA determined that the following subcategories generate

oil-bearing wastewater: Oily Wastes, Railroad Line Maintenance, and Shipbuilding Dry Docks. This

section describes EPA’s proposed regulated pollutant selection criteria for direct dischargers in the oilbearing subcategories. 

EPA did not select the 39 pollutants of concern presented in Table 7-11 that are

controlled through the regulation of other pollutants in the oil-bearing subcategories.
7.0 - Selection of Pollutant Parameters

7-22

Table 7-11

Pollutants Not Selected for Proposed Regulation for the Oil-Bearing

Subcategories Because They Are Controlled Through the Regulation of

Other Pollutants

Other Nonconventional Pollutants

 COD Total Recoverable Phenolics

 Total Petroleum Hydrocarbons (as SGT-HEM)

Nonconventional Organic Pollutants

 1,4-Dioxane n-Decane

 1-Bromo-2-Chlorobenzene n-Docosane

 1-Bromo-3-Chlorobenzene n-Dodecane

 2-Butanone n-Eicosane

 2-Hexanone n-Hexacosane

 2-Propanone n-Nitrosopiperidine

 4-Methyl-2-Pentanone n-Octacosane

 Acetophenone n-Octadecane

 Alpha-Terpineol n-Tetracosane

 Benzyl Alcohol n-Triacontane

 Diphenyl Ether o+p Xylene

 Diphenylamine o-Cresol

 Hexanoic Acid o-Xylene

 Isobutyl Alcohol p-Cresol

 m+p Xylene Pyridine

 m-Xylene Styrene

 Methyl Methacrylate Trichlorofluoromethane

 n,n-Dimethylformamide Tripropylenenglycol Methyl Ether
7.0 - Selection of Pollutant Parameters

7-23

COD is a method for measuring the oxygen demand of wastewater. For the oilbearing subcategories, EPA did not select COD for proposed regulation, but instead is proposing

alternative parameters for measuring the oxygen demand of a wastewater. For the Oily Wastes

subcategory, EPA is proposing a limit for Total Organic Carbon (TOC), an alternate method that

measures all oxidizable organic material in a waste stream, including some organic chemicals not

oxidized (and, therefore not detected) in the COD test. EPA chose TOC as an indicator parameter

because of its ability to measure all types of organic pollutants and is found to be the best general

indicator parameter for measuring the sum of organic compounds in an MP&M waste stream. For the

Railroad Line Maintenance subcategory, EPA is proposing limitations for BOD5 rather than COD, and

for the Shipbuilding Dry Dock subcategory it has determined that the regulation of only O&G was

necessary to control the removal of organic constituents. 

EPA did not propose a limit for Total Petroleum Hydrocarbons (TPH) (as SGT-HEM)

because it believes that the regulation of O&G (as HEM) and EPA’s proposed organics control options

will control the discharge of TPH (as SGT-HEM). The parameter Total Recoverable Phenolics will be

controlled through the regulation of the Total Organics Parameter (TOP) which includes compounds

such as phenol. EPA also believes that the list of 36 nonconventional organic compounds listed in

Table 7-11 will be controlled through the regulation of TOP. The organic parameters that comprise the

TOP are explained in more detail later in this section. 

Table 7-12 presents 28 pollutants of concerns that are present in only trace amounts in

the oil-bearing subcategories and/or are not likely to cause toxic effects. EPA determined that it was

not necessary to propose limits for these metals listed because it detected these metals at low levels in

its sampling of oil-bearing wastewater. As shown in Table 5-10, the average concentration at the

influent to treatment for each of these metals is less than 0.1 mg/L. 

Table 7-12

Pollutants Not Selected for Proposed Regulation for the Oil-Bearing

Subcategories Because They Are Present in Only Trace Amounts and/or

Are Not Likely to Cause Toxic Effects

Priority Metals

 Antimony Cyanide

 Arsenic Mercury

 Beryllium Nickel

 Cadmium Selenium

 Chromium Silver

 Copper Thallium
Table 7-12 (Continued)

7.0 - Selection of Pollutant Parameters

7-24

Nonconventional Metals

 Cobalt Titanium

 Gold Vanadium

 Molybdenum Yttrium

 Tin

Nonconventional Organic

 Carbon Disulfide

Other Nonconventional Pollutants

 Amenable Cyanide Total Dissolved Solids

 Ammonia as Nitrogen Total Kjeldahl Nitrogen

 Fluoride Weak-Acid Dissociable Cyanide

 Hexavalent Chromium Ziram

EPA did not select the 7 pollutants of concern presented in Table 7-13 for proposed

regulation in the oil-bearing subcategories because they may be used as treatment chemicals in the

MP&M industry.

Table 7-13

Pollutants Not Selected for Proposed Regulation for the Oil-Bearing

Subcategories Because They May Serve as Treatment Chemicals in the

MP&M Industry

Nonconventional Metals

 Aluminum Magnesium

 Calcium Sodium

 Iron

Other Nonconventional Pollutants

 Chloride Sulfate

EPA did not select the 6 pollutants of concern presented in Table 7-14 for proposed

regulation in the oil-bearing subcategories because they are not controlled by the selected BPT/BAT

technology.
7.0 - Selection of Pollutant Parameters

7-25

Table 7-14

Pollutants Not Selected for Proposed Regulation for the Oil-Bearing

Subcategories Because They Are Not Controlled by the

Selected BPT/BAT Technology

Priority Metal Pollutants

 Lead Zinc

Nonconventional Metal Pollutants

 Barium Manganese

 Boron

Other Nonconventional Pollutant

 Total Phosphorous

In order to determine the pollutants proposed for regulation for each of the oil-bearing

subcategories, EPA considered each of the remaining pollutants in Table 7-15 on a subcategory-bysubcategory basis. That is, after eliminating the pollutants listed in Tables 7-11 through 7-14 by

analyzing all of the data for the oil-bearing subcategories combined, EPA then considered only data

from each individual subcategory in order to determine the proposed regulated pollutants for each

subcategory. 

Table 7-15

49 Remaining Pollutants Considered for Proposed Regulation

for the Oil-Bearing Subcategories 

Conventional Pollutants

 BOD5 Total Suspended Solids

 Oil and Grease

Other Nonconventional Pollutants

 Total Organic Carbon Total Sulfide

Priority Organic Pollutants

 1,1,1-Trichloroethane Di-n-Butyl Phthalate

 1,1-Dichloroethane Di-n-Octyl Phthalate

 1,1-Dichloroethylene Dimethyl Phthalate

 2,4-Dimethylphenol Ethylbenzene

 2,4-Dinitrophenol Fluoranthene
Table 7-15 (Continued)

7.0 - Selection of Pollutant Parameters

7-26

 2,6-Dinitrotoluene Fluorene

 2-Nitrophenol Isophorone

 4-Chloro-m-cresol Methylene Chloride

Priority Organic Pollutants (continued)

 4-Nitrophenol n-Nitrosodimethylamine

 Acenaphthene n-Nitrosodiphenylamine

 Acrolein Naphthalene

 Anthracene Phenanthrene

 Benzyl Butyl Phthalate Phenol

 Bis(2-Ethylhexyl) Phthalate Pyrene

 Chlorobenzene Tetrachloroethene

 Chloroethane Toluene

 Chloroform Trichloroethylene

Nonconventional Organic Pollutants

 1-Methylfluorene Biphenyl

 1-Methylphenanthrene Carbon Disulfide

 2-Isopropylnaphthalene Dibenzofuran

 2-Methylnaphthalene Dibenzothiophene

 3,6-Dimethylphenanthrene n-Hexadecane

 Aniline n-Tetradecane

 Benzoic Acid p-Cymene

7.2.2.1 Oily Wastes Subcategory

For the direct dischargers in the Oily Wastes subcategory, EPA is proposing effluent

limitations for all of the pollutants listed in Table 7-15 except for BOD5. EPA is proposing an effluent

limitation for O&G and TOC for this subcategory and therefore determined that BOD5 would be

controlled by the regulation of these parameters. For the organic parameters listed in Table 7-14,

facilities in the Oily Wastes subcategory may choose from the following three options in order to

comply with the regulation: comply with the limit for TOC; comply with the limit for TOP; or implement

an organic pollutant management plan. Section 14 lists the effluent limitations for direct dischargers in

the Oily Wastes subcategory.
7.0 - Selection of Pollutant Parameters

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7.2.2.2 Railroad Line Maintenance Subcategory

For the direct dischargers in the Railroad Line Maintenance subcategory, EPA is

proposing effluent limitations for all of the pollutants listed in Table 7-15 except for TOC, total sulfide,

and all of the priority and nonconventional pollutants (represented as TOP). EPA is proposing effluent

limitations for O&G and BOD5 for this subcategory and therefore determined that TOC and the priority

and nonconventional organic pollutants would be controlled by the regulation of these parameters. EPA

is not proposing an effluent limit for total sulfide in this subcategory because of the small quantity of this

pollutant removed by proposed technology. EPA estimates that the regulation of total sulfide for the

Railroad Line Maintenance subcategory would result in the removal of 7.3 lbs/year or less than 0.2

lbs/facility. Section 14 lists the effluent limitations for the direct dischargers in the Railroad Line

Maintenance subcategory.

7.2.2.3 Shipbuilding Dry Dock Subcategory

For the direct dischargers in the Shipbuilding Dry Dock subcategory, EPA is proposing

effluent limitations for all of the pollutants listed in Table 7-15 except for BOD5, TOC, total sulfide, and

all of the priority and nonconventional pollutants (represented as TOP). EPA is proposing effluent

limitations for O&G for this subcategory and therefore determined that BOD5, TOC, and the priority

and nonconventional organic pollutants would be controlled by the regulation of O&G. EPA is not

proposing an effluent limit for total sulfide in this subcategory because of the small quantity of this

pollutant removed by the proposed technology. Many of the facilities in this subcategory already have

treatment in place, and therefore, the MP&m rule achieves very little additional removal of total sulfide. 

EPA estimates that the regulation of total sulfide for the Shipbuilding Dry Dock subcategory would

result in the removal of less than 1 lb/yr. Section 14 lists the effluent limitations for the direct

dischargers in the Shipbuilding Dry Dock subcategory.

 

7.3 Pollutants Proposed to be Regulated for Indirect Dischargers

For indirect dischargers, before proposing national technology-based pretreatment

standards, EPA examines whether the pollutants discharged by an industry “pass through” POTWs to

waters of the U.S. or interfere with POTW operation or sludge disposal practices. Section 307(b) of

the CWA requires EPA to promulgate pretreatment standards for existing sources (PSES) and new

sources (PSNS). The Agency establishes pretreatment standards to ensure removal of pollutants that

pass through or interfere with POTWs. EPA evaluated POTW pass-through for the MP&M pollutant

parameters of concern listed in Tables 7-10 and 7-15. 

Sections 7.3.2 and 7.3.3 discuss the results of the pass-through analysis for exiting and

new sources, respectively.
7.0 - Selection of Pollutant Parameters

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7.3.1 Pass-through Analysis for Indirect Dischargers

Generally, to determine if pollutants pass through POTWs, EPA compares the

percentage of the pollutant removed by well-operated POTWs achieving secondary treatment with the

percentage of the pollutant removed by direct discharging industrial facilities applying BAT for that

pollutant. The Agency determines that a pollutant “passes through” the POTW when the average

percentage removed by POTWs nationwide is less than the percentage removed by direct discharging

industrial facilities applying the BAT technology basis. In this manner, EPA can ensure that the

combined treatment at indirect discharging facilities and POTWs is at least equivalent to that obtained

through treatment by a direct discharger using BAT technology.

EPA compares removals for two reasons: (1) to ensure that wastewater treatment

performance for indirect dischargers is equivalent to that for direct dischargers, and (2) to recognize

and take into account the treatment capability and performance of the POTW in regulating the

discharge of pollutants from indirect dischargers. Rather than compare the mass or concentration of

pollutants discharged by POTWs with the mass or concentration of pollutants discharged by BAT

facilities, EPA compares the percentage of the pollutants removed by BAT facilities to the POTW

removals. EPA takes this approach because a comparison of the mass or concentration of pollutants in

POTW effluents with pollutants in BAT facility effluents would not take into account the mass of

pollutants discharged to the POTW from other industrial and non-industrial sources, nor the dilution of

the pollutants in the POTW to lower concentrations from the addition of large amounts of other

industrial and non-industrial water.

EPA conducted the pass through removal comparison on the priority and

nonconventional metal pollutants regulated under BAT for each subcategory. The Agency did not

perform this assessment for the regulated conventional pollutants, namely BOD5, TSS, and O&G, since

the conventional pollutants are generally not regulated under PSES and PSNS. EPA also did not

perform the pass through analysis for the priority and nonconventional organic pollutants that comprise

the TOP nor did it perform the analysis for TOC. Since EPA is proposing limitations for TOP and

TOC as part of an organic indicator option for direct dischargers, the Agency also decided that it was

appropriate to propose the same organic indicator alternatives for indirect dischargers. Similarly, the

Agency did not perform the pass-through analysis for amenable cyanide. EPA is proposing a limit for

direct dischargers for amenable cyanide as an alternative to total cyanide as a way to provide

monitoring flexibility. The Agency decided that it was appropriate to propose the same cyanide

monitoring alternatives for indirect dischargers as those proposed for directs, and therefore, it did not

perform the pass-through analysis for amenable cyanide.

The primary source of the POTW percent removal data is the “Fate of Priority

Pollutants in Publicly Owned Treatment Works” (EPA 440/1-82/303, September 1982), commonly

referred to as the “50-POTW Study.” This study presents data on the performance of 50 welloperated POTWs that employ secondary biological treatment in removing pollutants. Each sample was

analyzed for three conventional, 16 non-conventional, and 126 priority toxic pollutants. EPA used
7.0 - Selection of Pollutant Parameters

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percent removals data from the 50-POTW Study for all of the pollutants for which EPA applied the

pass-through analysis (i.e., those pollutants proposed for regulation at BAT).

In using the 50-POTW Study data to estimate percent removals, EPA has established

data editing criteria for determining pollutant percent removals. Some of the editing criteria are based

on differences between POTW and industry BAT treatment system influent concentrations. For many

toxic pollutants, POTW influent concentrations were much lower than those of BAT treatment systems. 

For many pollutants, particularly organic pollutants, the effluent concentrations from both POTW and

BAT treatment systems were below the level that could be found or measured. As noted in the 50-

POTW Study, analytical laboratories reported pollutant concentrations below the analytical threshold

level, qualitatively, as “not detected” or “trace,” and reported a measured value above this level. 

Subsequent rulemaking studies such as the 1987 OCPSF study used the analytical method nominal

minimum level (ML) established in 40 CFR Part 136 for laboratory data reported below the analytical

threshold level. Use of the nominal ML may overestimate the effluent concentration and underestimate

the percent removal.

At the time of the 50-POTW sampling program, which spanned approximately 2.5

years (July 1978 to November 1980), EPA collected samples at selected POTWs across the U.S. 

The samples were subsequently analyzed by either EPA or EPA-contract laboratories using test

procedures (analytical methods) specified by the Agency or in use at the laboratories. Laboratories

typically reported the analytical method used along with the test results. However, for those cases in

which the laboratory specified no analytical method, EPA was able to identify the method based on the

nature of the results and knowledge of the methods available at the time.

Each laboratory reported results for the pollutants for which it tested. If the laboratory

found a pollutant to be present, the laboratory reported a result. If the laboratory found the pollutant

not to be present, the laboratory reported either that the pollutant was "not detected" or a value with a

“less than” sign (<) indicating that the pollutant was below that value. The value reported along with the

“less than” sign was the lowest level to which the laboratory believed it could reliably measure. EPA

subsequently established these lower levels as the MLs of quantitation. In some instances, different

laboratories reported different (sample-specific) MLs for the same pollutant using the same analytical

method. 

Because of the variety of reporting protocols among the 50-POTW Study laboratories

(pages 27 to 30, 50-POTW Study), EPA reviewed the percent removal calculations used in the passthrough analysis for previous industry studies, including those performed when developing effluent

guidelines for Organic Chemicals, Plastics, and Synthetic Fibers (OCPSF) Manufacturing, Centralized

Waste Treatment (CWT), and Commercial Hazardous Waste Combustors. EPA found that, for 12

parameters, different analytical MLs were reported for different rulemaking studies (10 of the 21

metals, cyanide, and one of the 41 organics).
7.0 - Selection of Pollutant Parameters

7-30

To provide consistency for data analysis and establishment of removal efficiencies, EPA

reviewed the 50-POTW Study, standardized the reported MLs for use in the final rules for CWT and

Transportation Equipment Cleaning Industries and for this proposed rule and the Iron and Steel

proposed rule. A more detailed discussion of the methodology used and the results of the ML

evaluation are contained in the MP&M public record.

Because the data collected for evaluating POTW percent removals included both

effluent and influent levels that were close to the analytical detection levels, EPA devised hierarchal data

editing criteria to exclude data with low influent concentration levels, thereby minimizing the possibility

that low POTW removals might simply reflect low influent concentrations instead of being a true

measure of treatment effectiveness.

EPA has generally used hierarchic data editing criteria for the pollutants in the 50-

POTW Study. For the MP&M proposal, as in previous rulemakings, EPA used the following editing

criteria:

1) Delete both influent and effluent data on a given date if either datum has a notation

of analytical interference;

2) Substitute a pollutant-specific analytical “minimum level” for values “reported as “not

detected,” “trace,” “less than [followed by a number],” or a number” less than the

analytical minimum level established by the reporting laboratory;

3) Delete pollutants that have fewer than three pairs of data points (influent/effluent);

4) Delete pollutant influent and corresponding effluent values if the average pollutant

influent level is less than 10 times the pollutant minimum level; and

5) If none of the average pollutant influent concentrations exceeded 10 times the ML,

then delete average influent values less than 20 :g/l or twice the ML (2XML) along

with the corresponding average effluent values.

EPA then calculates each POTW percent removal for each pollutant based on its

average influent and its average effluent values. The national POTW percent removal used for each

pollutant in the pass-through test is the median value of all the POTW pollutant specific percent

removals.

The rationale for retaining POTW data using the “10xML” editing criterion is based on

the BAT organic pollutant treatment performance editing criteria initially developed for the 1987

OCPSF regulation (52 FR 42522, 42545-48; November 5, 1987). BAT treatment system designs in

the OCPSF industry typically achieved at least 90 percent removal of toxic pollutants. Since most of

the OCPSF effluent data from BAT biological treatment systems had values of “not detected,” the

average influent concentration for a compound had to be at least 10 times the analytical minimum level
7.0 - Selection of Pollutant Parameters

7-31

for the difference to be meaningful (demonstration of at least 90 percent removal) and qualify effluent

concentrations for calculation of effluent limits.

EPA is evaluating several issues related to its traditional methodology for determining

POTW performance and explains these issues in detail in Appendix A to this Section. 

7.3.2 Pass-through Analysis Results for Existing Sources

 For each of the MP&M subcategories, EPA calculated the percentage of a pollutant

removed by BAT treatment systems using the median percent removal achieved by BAT facilities that it

used for determining effluent limitations for direct dischargers. To determine pass-through, it compared

this median percent removal for BAT facilities to the median percent removal determined from the 50-

POTW database. Table 7-16 presents the results of the pass-through analysis for the metal-bearing

wastewater subcategories.

Table 7-16

Pass-Through Analysis Results for Existing Sources for Metal-Bearing

Wastewater Subcategories

Pollutant

Median BAT Percent Removal by Subcategory Median

POTW

Percent

General Metals Removal (c)

Metal Finishing

Job Shops

NonChromium

Anodizing

Printed Wiring

Boards

Steel Forming

and Finishing

(b)

 Amenable Cyanide (a) 99.6 99.6 NA 99.6 99.6 57.4

 Cadmium 92.2 98.8 NA NA 92.2 90.1

 Chromium 99 96.7 NA 99.0 (b) 99 80.3

 Copper 95.8 95.9 NA 96.3 95.8 84.2

 Cyanide (a) 99.1 99.1 NA 99.1 99.1 70.4

 Lead 99.4 99.6 NA 99.4 (b) 99.4 77.5

 Manganese 96.9 98.8 96.9 (b) 57.7 96.9 35.5

 Molybdenum 64.7 64.7 (b) NA NA 64.7 18.9

 Nickel 96.3 93.7 96.3 (b) 89.3 96.3 51.4

 Silver 94.8 96.5 NA NA 94.8 88.3

 Tin 98.8 97.8 NA 98.1 98.8 42.6

 Zinc 98 97.1 98.0 (b) 98.0 (b) 98 79.1

(a) EPA determined BAT percent removals for Total Cyanide using data from all subcategories. 

(b) EPA transferred BAT percent removal from General Metals Subcategory. 

(c) All POTW percent removals determined from 50-POTW Study.

NA = Pollutant not proposed for BAT regulation for the specific subcategory therefore pass through analysis does

not apply. 
7.0 - Selection of Pollutant Parameters

7-32

EPA compared the BAT percent removals and the POTW percent removals shown in

Table 7-16 and determined that all of these pollutants pass through POTWs. In addition to the

pollutants listed in Table 7-16, EPA is proposing pretreatment standards for Total Sulfide for the

General Metals, Metal Finishing Job Shops, Printed Wiring Board, and Steel Forming and Finishing

subcategories. The Agency is proposing a limitation for total sulfide based on potential POTW

interference or upset associated with discharges of this pollutant from MP&M facilities (i.e., through

corrosion of pipes from formatting sulfuric acid or hazardous conditions to POTW employees from

generation of hydrogen sulfide gas). EPA is also proposing pretreatment standards for TOC and TOP

as part of a compliance alternative for organic pollutant discharges. See Section 15.2.6 for a discussion

of the proposed monitoring alternatives for organic pollutants. Section 14 lists the pretreatment

standards for the pollutants proposed for regulation for indirect dischargers in each of the

subcategories.

For the three subcategories that generate primarily oil-bearing wastewater (Oily

Wastes, Railroad Line Maintenance, and Shipbuilding Dry Dock), EPA is only establishing

pretreatment standards for the Oily Wastes subcategory. For the reasons discussed in detail in Section

14, EPA is not proposing pretreatment standards for the Railroad Line Maintenance nor the

Shipbuilding Dry Dock subcategories. For the Oily Wastes subcategory, EPA is proposing

pretreatment standards for TOP, TOC and total sulfide. The Agency is proposing a limitation for total

sulfide based on potential POTW interference or upset associated with discharges of this pollutant from

MP&M facilities. EPA is also proposing pretreatment standards for TOC and TOP as part of a

compliance alternative for organic pollutant discharges. See Section 15.2.6 for a discussion of the

proposed monitoring alternatives for organic pollutants. Section 14 lists the pretreatment standards for

the pollutants proposed for regulation for indirect dischargers in the Oily Wastes subcategory. 

7.3.3 Pass-through Analysis Results for New Sources

 For each of the MP&M subcategories, EPA calculated the percentage of a pollutant

removed by NSPS treatment systems using the median percent removal achieved by NSPS facilities

that it used for determining effluent limitations for new direct dischargers. To determine pass-through, it

compared this median percent removal for NSPS facilities to the median percent removal determined

from the 50-POTW database. Table 7-17 presents the results of the pass-through analysis for the

metal-bearing wastewater subcategories:
7.0 - Selection of Pollutant Parameters

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Table 7-17

Pass-Through Analysis Results for New Sources for Metal-Bearing

Wastewater Subcategories

Pollutant

Median NSPS Percent Removal by Subcategory

Median POTW

Percent

General Metals Removal(c)

Metal

Finishing Job

Shops

NonChromium

Anodizing (d)

Printed

Wiring Boards

Steel Forming

and Finishing

(d)

 Cadmium 99.8 99.8 (d) NA NA 99.8 90.1

 Chromium 99.4 99.4 (d) NA 99.4 (d) 99.4 80.3

 Copper 97.8 97.8 (d) NA 100 97.8 84.2

 Cyanide (a) 99.1 99.1 NA 99.1 99.1 70.4

 Lead 99.4 (b) 99.4 (b) NA 99.1 99.4 77.5

 Manganese 96.3 96.3 (d) 96.9 (b) 96.3 (d) 96.3 35.5

 Molybdenum 64.7 (b) 64.7 (b) NA NA 64.7 18.9

 Nickel 97.6 97.6 (d) 96.3 (b) 97.6 (d) 97.6 51.4

 Silver 99.4 99.4 (d) NA NA 99.4 88.3

 Tin 98.5 98.5 (d) NA 98.9 98.5 42.6

 Zinc 99.8 99.8 (d) 98.0 (b) 99.8 (d) 99.8 79.1

(a) EPA determined NSPS percent removals for Total Cyanide using data from all subcategories. 

(b) EPA transferred BAT percent removal from General Metals Subcategory. 

(c) All POTW percent removals determined from 50-POTW Study.

(d) EPA transferred NSPS percent removals from General Metals subcategory.

NA = Pollutant not proposed for NSPS regulation for the specific subcategory therefore pass through analysis does

not apply. 

EPA compared the NSPS percent removals and the POTW percent removals shown

in Table 7-17 and determined that all of these pollutants pass through POTWs. In addition to the

pollutants listed in Table 7-17, EPA is proposing pretreatment standards for new sources for Total

Sulfide for the General Metals, Metal Finishing Job Shops, Printed Wiring Board, and Steel Forming

and Finishing subcategories. The Agency is proposing a limitation for total sulfide based on potential

POTW interference or upset associated with discharges of this pollutant from MP&M facilities (i.e.,

through corrosion of pipes from formation of sulfuric acid or hazardous conditions to POTW employees

from generation of hydrogen sulfide gas). EPA is also proposing pretreatment standards for new

sources for TOC and TOP as part of a compliance alternative for organic pollutant discharges. See

Section 15.2.6 for a discussion of the proposed monitoring alternatives for organic pollutants. Section
7.0 - Selection of Pollutant Parameters

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14 lists the pretreatment standards for new sources for the pollutants proposed for regulation for

indirect dischargers in each of the subcategories.

For the reasons described in Section 14, EPA is proposing pretreatment standards for

new sources (PSNS) for the Oily Wastes subcategory equivalent to those proposed for existing

sources. In addition, the Agency also explains in Section 14 its rationale for not proposing PSNS for

the Railroad Line Maintenance and the Shipbuilding Dry Docks subcategories.

7.4 References

1. U.S. Environmental Protection Agency. The 1990 Industrial Technology Division List

of Analytes. Washington, DC, May 1990.

2. U.S. Environmental Protection Agency. Development Document for the Centralized

Waste Treatment Industry, December 1998.

3. U.S. Environmental Protection Agency. Fate of Priority Pollutants in Publicly Owned

Treatment Works, EPA-440/1-82/303. Washington DC, September 1982. 
7.0 - Selection of Pollutant Parameters

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Appendix A

Proposed Revisions to the Methodology Used to Determine

POTW Performance for Toxic and Non-Conventional Pollutants

For the MP&M proposal, EPA used its traditional methodology to determine POTW

performance (percent removal) for toxic and non-conventional pollutants. POTW performance is a

component of the pass-through methodology used to identify the pollutants to be regulated for PSES

and PSNS. It is also a component of the analysis to determine net pollutant reductions (for both total

pounds and toxic pound-equivalents) for various indirect discharge technology options. However, as

discussed in more detail below, EPA is considering revisions to its traditional methodology for

determining POTW performance (percent removals) for toxic and non-conventional pollutants. In the

traditional methodology, the pertinent data selection editing criteria used to determine POTW percent

removals were based on the editing criteria used for industry data to calculate BAT limitations. 

However, since POTWs are designed to treat conventional pollutants, not toxic pollutants, the revised

editing criteria would more accurately reflect the incidental removals of toxic pollutants in POTWs.

Background

Unlike direct dischargers whose wastewater will receive no further treatment once it

leaves the facility, indirect dischargers send their wastewater streams to POTWs for further treatment. 

However, POTWs typically install secondary biological treatment systems which are designed to

control conventional pollutants [biochemical oxygen demand (BOD), total suspended solids (TSS), oil

& grease (O&G), pH, and fecal coliform] -- the principal parameters for characterizing domestic

sewage. With the exception of nutrient control for ammonia and phosphorus, POTWs usually do not

install specific technology (advanced or tertiary treatment) to control toxic and non-conventional 

pollutants, although incidental removals in secondary biological treatment systems may be significant for

some toxic pollutants. Instead, the Clean Water Act envisions that, through implementation of

pretreatment programs and industrial compliance with categorical pretreatment standards, toxic and

non-conventional pollutants in municipal effluents will be controlled adequately.

Therefore, for indirect dischargers, before proposing national technology-based

pretreatment standards, EPA examines whether the pollutants discharged by an industry “pass through”

POTWs to waters of the U.S. or interfere with POTW operation or sludge disposal practices. 

Generally, to determine if pollutants pass through POTWs, EPA compares the percentage of the

pollutant removed by well-operated POTWs achieving secondary treatment with the percentage of the

pollutant removed by direct discharging industrial facilities applying BAT for that pollutant. A pollutant

is determined to “pass through” the POTW when the average percentage removed by POTWs

nationwide is less than the percentage removed by direct discharging industrial facilities applying the

BAT technology basis. In this manner, EPA can ensure that the combined treatment at indirect
7.0 - Selection of Pollutant Parameters

7-36

discharging facilities and POTWs is at least equivalent to that obtained through treatment by a direct

discharger using BAT technology.

For specific pollutants, such as volatile organic compounds, EPA may use other means

to determine pass-through. These evaluations may include chemical and physical properties (e.g.,

Henry’s Law constants, octanol/water partition coefficients, and water solubility constants) and

empirical data to estimate amounts of volatilization, biodegradation, and/or partitioning to the residue

solids phase.

Traditional Methodology for Determination of POTW Percent Removals

The primary source of the POTW data is the “Fate of Priority Pollutants in Publicly

Owned Treatment Works” (EPA 440/1-82/303, September 1982), commonly referred to as the “50-

POTW Study.” At most of these POTWs, EPA collected a minimum of 6 days of 24-hour composite

influent and effluent wastewater samples. EPA analyzed each sample for the conventional pollutants

(excluding fecal coliform), selected non-conventional pollutants, and the 126 priority pollutants. The

conventional pollutants, listed at 40 CFR 401.16, are BOD5,TSS, O&G, pH, and fecal coliform. The

selected non-conventional pollutants included chemical oxygen demand, total organic carbon, total

phenols, ammonia nitrogen, iron, aluminum, and magnesium, among several others. The priority

pollutants consist of the 126 compounds (listed in Appendix A of 40 CFR Part 423) that are a subset

of the 65 toxic pollutants and classes of pollutants referred to in Section 307(a) of the Clean Water Act

and listed at 40 CFR 401.15. A total of 102 of the 126 priority toxic pollutants were detected at least

once in POTW influents (page 1, 50-POTW Study). 

In using the 50-POTW Study data to estimate percent removals, EPA established data

editing criteria for determining pollutant percent removals. Some of the editing criteria are based on

differences between POTW and industry BAT treatment system influent concentrations. For many

pollutants, POTW influent concentrations were much lower than those of BAT treatment systems. For

many pollutants, particularly organic pollutants, the effluent concentrations from both POTW and BAT

treatment systems, were below the level that could be found or measured. As noted in the 1982 50-

POTW Study, analytical laboratories reported pollutant concentrations below the analytical minimum

level , qualitatively, as “not detected” or “trace,” and reported a measured value above this level (pages

27 to 30). Subsequent rulemaking studies such as the 1987 OCPSF study used the analytical method 

“minimum level” (ML) established in 40 CFR Part 136 for laboratory data reported below the

analytical threshold level. Use of the ML may overestimate the effluent concentration and

underestimate the percent removal. (If the actual effluent concentration is less than the ML, then the

calculated percent removal based on the actual value would be higher.) Because the data collected for

evaluating POTW percent removals included both effluent and influent levels that were close to the

analytical MLs, EPA devised hierarchal data editing criteria to exclude data with low influent

concentration levels, thereby minimizing the possibility that low POTW removals might simply reflect

low influent concentrations instead of being a true measure of treatment effectiveness.
7.0 - Selection of Pollutant Parameters

1

 These 50-POTW Study data editing criteria may vary among effluent guideline development studies. 

2

 Of the 57 regulated organic pollutants, limits for 34 (60 percent) were based on long-term averages of “not

detected” or the analytical minimum level (“Development Document for Effluent Limitations Guidelines and

Standards for the Organic Chemicals, Plastics, and Synthetic Fibers Point source Category” – the “OCPSF DD,” 

(EPA 440/1-87/009), October 1987, Vol. I, pages VII-208 to VII-210). 

7-37

EPA has generally used the following hierarchic data editing criteria1 for the pollutants in

the 50-POTW Study:

1) Delete both influent and effluent data on a given date if either datum has a notation of

analytical interference,

2) Substitute a pollutant-specific analytical “minimum level” for values reported as “not

detected”, “trace”, “less than [followed by a number]”, or a number less than the

analytical minimum level established by the reporting laboratory,

3) Delete pollutants that have fewer than three pairs of data points (influent/effluent),

4) Delete pollutant influent and corresponding effluent values if the average pollutant

influent level is less than 10 times the pollutant ML, and

5) If none of the average pollutant influent concentrations exceeded 10xML, then delete

average influent values less than 20 :g/l or twice the minimum level (2xML) along with

the corresponding average effluent values.

EPA then calculated each POTW percent removal for each pollutant based on its

average influent and its average effluent values. The POTW percent removal used for each pollutant in

the pass-through test was the median value of all the POTW pollutant specific percent removals.

The rationale for retaining POTW data using the “10 times the pollutant minimum level”

editing criterion was based on the BAT organic pollutant treatment performance editing criteria initially

developed for the 1987 organic chemicals, plastics, and synthetic fibers (OCPSF) regulation (40 CFR

Part 414; 52 FR 42522 at 42545 to 48). BAT treatment system designs in the OCPSF industry

typically achieved at least 90 percent removal of toxic pollutants. Since most of the OCPSF effluent

data from BAT biological treatment systems had values of “not detected,”2 the average influent

concentration for a compound had to be at least 10 times the analytical ML for the difference to be

meaningful (demonstration of at least 90 percent removal) and qualify effluent concentrations for

calculation of effluent limits (“OCPSF DD,” Vol. I, page VII-183).
7.0 - Selection of Pollutant Parameters

7-38

Review of the 50-POTW Study Analytical Laboratory Reporting Practices and Standardization

of Minimum Level Values 

At the time of the 50-POTW sampling program which spanned approximately 2 1⁄2

years (July 1978 to November 1980), EPA collected samples at selected POTWs across the U.S. 

The samples were subsequently analyzed by either EPA or EPA-contract laboratories using test

procedures (analytical methods) specified by the Agency or in use at the laboratories. Laboratories

typically reported the analytical method used along with the test results. However, for those cases in

which the laboratory specified no analytical method, EPA was able to specify the method based on the

nature of the results and knowledge of the methods available at the time. 

To provide consistency for data analysis and establishment of removal efficiencies, EPA

reviewed the 50-POTW Study, standardized the reported MLs for use in the CWT final rule and the

MP&M proposal. EPA standardized the MLs based on information about the analytical methods used,

laboratory capabilities at the time the testing was conducted (1978 to 1980), MLs that had been

achievable historically, and consultation with Agency experts in the field of analytical chemistry. The

standardized MLs are used in this reassessment.

Reassessment of the Pass-Through Methodology and Revised Editing Criteria

The Agency has reevaluated several aspects of the 50-POTW Study data base editing

process and is considering changes to the editing criteria. Several minor editing criteria changes that

EPA is considering for use in the final MP&M pretreatment standard including those related to the

presence of analytical interferences, missing data, reported greater-than values, and reported less-than

values higher than the MLs are described in Appendix B, “Revised Data Conventions for the 50-

POTW Study Analytical Data.” To compare the proposed changes to the traditional editing criteria

used for the MP&M proposal, additions to the criteria are highlighted as “(New)” and revisions to

existing criteria are highlighted as “(Revised).”

The principal editing criterion of the pass-through analysis used for the MP&M

proposal -- using available performance data representing average influent concentrations 10 times the

analytical ML. This is also the primary editing criteria for ensuring that promulgated effluent limitations

guidelines and standards are based only on the performance of BAT wastewater treatment systems

with meaningful influent concentrations of pollutants. This editing criterion ensures that BAT data would

demonstrate at least 90 percent removal of toxic pollutants. EPA selected this criterion for the POTW

data for similar reasons. However, after reconsidering the design differences between industrial BAT

treatment and POTW treatment systems as well as the differences in toxic pollutant influent

concentrations, EPA believes that the “10xML” editing criterion is too restrictive for the purpose of

analyzing POTW data, especially where effluent values are above the ML.
7.0 - Selection of Pollutant Parameters

3

 The 1996 Clean Water Needs Survey found that of the 13,992 discharging POTWs, 1.3 percent reported less than

secondary treatment, 67.1 percent reported secondary treatment, and the remaining 31.6 percent reported better than

secondary treatment (www.epa.gov/owm/uc.htm at Appendix C).

4

 Hydraulic residence times for the conventional and tapered aeration activated sludge processes range from 4 to 8

hours; for the step aeration and contact stabilization processes, from 3 to 6 hours; for the modified and high-rate

aeration processes, from 0.5 to 3 hours; and for the extended aeration process, from 18 to 36 hours (1992 WEF

Manual of Practice No. 8, page 627, Vol. I). 

5

 Typical POTW unit operations include preliminary treatment (screening and grit removal), primary treatment

(sedimentation, sludge collection, and odor control), and secondary treatment (biological treatment with secondary

clarification). POTW unit operations associated with advanced or tertiary treatment include nutrient controls

(phosphorus and nitrogen [including ammonia] removal processes), multi-media filtration, and activated carbon (1992

WEF Manual of Practice No. 8, pages 389, 447, 517, and 675, Vol. I and pages 895 and 1013, Vol. II). 

6

 Based on 31 OCPSF biological treatment systems with residence times ranging from 4.5 to 1,008 hours

(“Development Document for Effluent Limitations Guidelines and Standards for the Organic Chemicals, Plastics, and

Synthetic Fibers Point source Category,” (EPA 440/1-87/009), October 1987, Vol. II, page VIII-45 and “Supplement to

the Development Document for Effluent Limitations Guidelines and Standards for the Organic Chemicals, Plastics,

and Synthetic Fibers Point source Category,” (EPA 821-R-93-007), May 1993, pages III-20 to 23).

7-39

The majority of discharging POTWs (67 percent) have installed secondary biological

treatment systems3 designed to treat conventional pollutants characteristic of domestic sewage

(primarily BOD5 and TSS). Most POTWs with secondary treatment have installed a variation of the

activated sludge biological process with typical wastewater hydraulic residence times ranging from 4 to

8 hours for the most prevalent process designs.4 Very few secondary POTWs install unit operations

specifically designed to remove toxic and non-conventional pollutants.5

In contrast, depending on raw waste characteristics, industrial treatment systems are

often designed to remove toxic pollutants using a wide variety of in-plant wastewater treatment unit

operations with or without end-of-pipe secondary biological treatment systems and sometimes followed

by tertiary controls. For example, plants in the MP&M, electroplating, iron and steel, OCPSF,

inorganic chemicals, landfills, commercial hazardous waste combustor, centralized waste treatment and

other industries may use in-process or end-of-pipe chemical precipitation for metals control, alkaline

chlorination for cyanide control, steam or air stripping for volatile organic pollutant control, and

activated carbon or biological treatment for control of a wide variety of organic pollutants. For plants in

the OCPSF industry with end-of-pipe secondary biological treatment systems, the median and average

wastewater hydraulic residence times are 48 and 118 hours, respectively.6 Most of the pollutantspecific treatment unit operations listed above are not used to treat POTW wastewater because of the

relatively low influent toxic pollutant concentrations. POTW toxic pollutant influent concentrations are

often orders of magnitude lower than industrial raw waste concentrations.

Because of these design and toxic pollutant influent concentration differences, the

POTW data editing criteria should reflect typical incidental removals of toxic pollutants in secondary

biological treatment systems designed and operated to control municipal sewerage. In general, due to
7.0 - Selection of Pollutant Parameters

7-40

dilution in municipal sewer collection systems, POTW influent concentrations of toxic pollutants are

lower than the influent concentrations of industrial treatment systems. In those cases where both

industrial and municipal treatment systems reduce the effluent pollutant concentration to the analytical

ML, the relative performance – percent removal -- is primarily a function of the influent concentrations. 

This was the principal reason for initially using the “10xML” influent editing criterion for retaining

POTW average performance data – to avoid the bias of calculating artificially low median percent

removals (median of POTW average performance). However, this editing criterion, when applied to

the 50-POTW Study data, overestimates POTW incidental removals for many toxic pollutants. In the

50-POTW Study data base, there are many cases where POTW average influent concentrations are

less than the “10xML” editing criterion and the average effluent data are above the ML. These cases

should be included in the calculation of national POTW performance (median of POTW average

percent removals) because they accurately reflect the incidental removals of the toxic pollutants in

treatment systems primarily designed for the control of conventional pollutants. For example, for many

POTWs in the study, average metal pollutant influent concentrations less than “10xML” are paired with

average effluent concentrations where each data point is measured above the analytical ML. Because

of these pairings, EPA can accurately calculate the incidental removals of toxic pollutants characteristic

of POTW designs and the characteristically low POTW toxic pollutant influent concentrations. EPA

believes it is reasonable to include these percent removal calculations in its pass-through analysis.

Furthermore, one of the observations and conclusions in the 50-POTW Study was that

for many pollutants, “as influent concentrations increased effluent concentrations also increased. This

implies that the removal rates for the priority pollutants are relatively constant and a fixed percentage of

incremental loadings of these pollutants will be removed by secondary treatment.” Therefore, except

for highly biodegradable compounds, for typical POTW secondary biological treatment designs without

specific unit operations for toxic pollutant control, one would not necessarily expect the percent

removals of toxic pollutants to increase (above incidental removal levels) as influent concentrations

increased.

Assessment of Editing Criteria for 50-POTW Performance by Treatment Technology

EPA is also considering incorporating POTW treatment system and BOD5/TSS

performance editing criteria into the methodology for determining POTW performance (percent

removal) for toxic and non-conventional pollutants.

A major goal of the 50-POTW study was to obtain toxic priority pollutant data from

representative types of secondary treatment facilities that would exist after completion of EPA’s

Construction Grants program. The 50 POTWs selected for sampling are representative of biological

treatment processes – 35 activated sludge, 8 trickling filter, 4 activated sludge with parallel trickling

filter, 1 rotating biological contactor, 1 aerated lagoon, and 1 lagoon system. Eight of these POTWs

include post-secondary or tertiary treatment (4 filtration and 4 lagoon systems). 
7.0 - Selection of Pollutant Parameters

7

 For most organic pollutants, the ML is 10 μg/l (several have MLs of 20 and 50 μg/l). For mercury, silver, cadmium,

zinc, copper, nickel, lead, and barium, the respective MLs are 0.2, 2, 5, 20, 25, 40, 50, and 200 μg/l.

7-41

The 50-POTW Study and subsequent assessments of POTW performance (including

the assessment for the MP&M proposal) used combined end-of-pipe data for all 50 POTWs. The

analyses did not assess potential differences in toxic pollutant reductions among the various types of

secondary systems, between secondary and tertiary systems, and among different levels of BOD5 and

TSS control (the principal design basis for POTW treatment systems).

After publication of the 50-POTW Study, EPA promulgated its Secondary Treatment

Regulation (40 CFR Part 133) to provide information on the level of effluent quality attainable through

the application of secondary or equivalent treatment. Secondary treatment generally refers to activated

sludge biological processes and treatment equivalent to secondary treatment refers to trickling filters or

waste stabilization ponds. The secondary treatment performance criteria for both BOD5 and TSS are

30-day and 7-day averages not exceeding 30 mg/l and 45 mg/l, respectively. The BOD5 and TSS

criteria for equivalent secondary treatment for both BOD5 and TSS are 30-day and 7-day averages not

exceeding 45 mg/l and 65 mg/l, respectively. These definitions and treatment levels provide the basis

for the technology and BOD5/TSS performance edits being proposed for use in the final rule.

The revised analyses under consideration include separating the data collected for the 4

parallel activated sludge and trickling filter systems and, for 2 of the tertiary systems, including the

secondary activated sludge sampling data. This expands the performance data base to 56 POTW

treatment trains – 41 activated sludge, 12 trickling filter, 1 rotating biological contactor, 1 aerated

lagoon, and 1 lagoon system. Again, 8 of these treatment trains include secondary or tertiary treatment

(4 filtration and 4 lagoon systems). Based on the definitions in 40 CFR Part 133, the POTW treatment

trains consist of 47 secondary or equivalent systems, 1 rotating biological contactor, and 8 postsecondary or tertiary systems. The Agency is considering a variety of POTW treatment train and

BOD5/TSS performance editing criteria to determine if these factors significantly affect the incidental

removals of toxic and non-conventional pollutants in POTWs. For example, among other alternatives,

EPA is considering editing criteria that would retain only those secondary or equivalent treatment trains

and the rotating biological contactor treatment train that meet the BOD5/TSS 7-day average

performance criteria. EPA is considering this alternative because it accounts for the fact that only 6

days of data were collected at each POTW.

Revised Editing Criteria for Determining POTW Performance

Based on these concerns, EPA is considering revising the POTW toxic and nonconventional pollutant performance (percent removal) editing criteria. Given the range of analytical

MLs7 and their influence on calculated percent removals as well as the range of in-place POTW

treatment technology, EPA is considering several editing alternatives including:
7.0 - Selection of Pollutant Parameters

7-42

 Alternative A – For POTW treatment trains that meet the 7-day conventional pollutant

performance criteria for BOD5 (45 mg/l or lower) and TSS (45 mg/l or lower) using

secondary activated sludge biological treatment or its equivalent:

 1. If all effluent values are equal to the ML and the ML is less than or equal to 20 μg/l,

retain the pollutant performance (percent removal) if the pollutant influent average is at

least ten times the nominal minimum level (10xML). 

2. If all effluent values are equal to the ML and the ML is greater than 20 mg/1, retain

the pollutant performance (percent removal) if the pollutant influent average is at least

ten times one-half the nominal minimum level [10 x (0.5xML) or 5 x ML].

3. If the effluent average is greater than the ML, retain the pollutant performance

(percent removal) regardless of the pollutant influent average. 

4. The national POTW/pollutant percent removal is the median of the retained values

from 1, 2, and 3 above.

Alternative B -- The same as Alternative A for items Al, A2, and A4 with the following

modification to item A3: If the effluent average is greater than the ML, retain the

pollutant performance (percent removal) if the pollutant influent average is at least two

times the nominal minimum level (2xML). Based on the analyses conducted to date,

this is the Agency’s preferred alternative.

Alternative C – Retain all toxic pollutant data for POTW treatment trains that meet the

7-day conventional pollutant performance criteria for BOD5 (45 mg/l or lower) and

TSS (45 mg/l or lower) using secondary activated sludge biological treatment or its

equivalent.

Alternative D -- The same as Alternative B with the following modifications: (a) Retain

POTW treatment trains with secondary biological treatment (as designated by treatment

flag “S”), only if both the effluent BOD5 and TSS average concentrations are less than

or equal to 45 mg/l. (b) Retain POTW treatment trains with equivalent to secondary

biological treatment (as designated by treatment flag “E”), only if both the effluent

BOD5 and TSS average concentrations are less than or equal to 65 mg/l. 

Alternative E -- The same as Alternative D with the following modification: 

substitute 0.5XML for all data points set equal to the analytical ML.

Table A-1 lists the national POTW percent removals for several pollutants, determined

by using the traditional methodology for the proposal (Column 2), Alternative A (Column 3),

Alternative B (Column 4), Alternative C (Column 5), Alternative D (Column 6), and Alternative E
7.0 - Selection of Pollutant Parameters

7-43

(Column 7). For the proposal, EPA has used the traditional methodology to estimate POTW percent

removals, and, therefore, whether these pollutants “pass through” for purposes of selecting pollutants

for regulation by PSES and PSNS. EPA solicits comments on its pass-through methodology, including

the revised editing criteria discussed above as well as for other alternatives.

Assessment of the Use of Analytical Minimum Levels

Since some commenters have concerns that EPA’s use of the ML for reported effluent

data of <ML underestimates actual percent removal, EPA tried to determine the extent of this situation

and possible effects on estimating POTW percent removals for the pass through analysis. The

assessment below indicates that the proportion of POTW not-detected effluent toxic pollutant data

varies from pollutant to pollutant and from POTW to POTW. 

To help characterize the effect of substituting the analytical ML for not-detected data,

the Agency assigned each POTW/pollutant data set to one of three groups based on the proportion of

not-detected effluent values, as follows:

1. All ND -- when all of the effluent data points were not detected or assigned the ML

value for the pollutant, 

2. All NC (non-censored) – when all of the effluent data points were measured

concentrations above the ML for the pollutant, and 

3. Mix (NC & ND) – when the effluent data points were a mixture of not-detect and

measured values.

For those cases where all of the effluent data were non-censored, the calculated

percent removal reflects POTW incidental removals with the most accuracy. For those cases where all

the effluent data were not detected, the calculated percent removal reflects POTW incidental removals

with the least accuracy. In those cases where the effluent data is a mixture of not detected and noncensored data, the calculated percent removals are probably more accurate than “All ND” but less

accurate than “All NC”. Table A-2 provides pollutant-by-pollutant tabulations for the number of

POTWs retained by the Alternative D data conventions with counts of the POTWs effluent data sets

that fall into each category.

 For the 21 metal pollutants retained by the Alternative D data conventions, about 97

percent of the 347 POTW/metal pollutant effluent data sets in the table are comprised of all NC (66

percent) and a mixture of NC & ND (31 percent) values. For ammonia and cyanide, 100 percent of

the 65 data sets are comprised of all NC (99.5 percent) and a mixture of NC & ND (0.5 percent)

values.
7.0 - Selection of Pollutant Parameters

7-44

The 28 organic pollutants retained by the Alternative D data conventions were divided

into low, medium, and high Henry’s Law Constant groups. For the six organics with low Henry’s Law

Constants (10-3 to 10-8), about 81 percent of the 38 POTW/organic pollutant effluent data sets in the

table are comprised of all NC (18 percent) and a mixture of NC & ND (63 percent) values. For the

nine organics with medium Henry’s Law Constants (10-1 to 10-3), about 83 percent of the 36

POTW/organic pollutant effluent data sets in the table are comprised of all NC (25 percent) and a

mixture of NC & ND (58 percent) values. For the 13 organics with high Henry’s Law Constants

(2x102 to 10-1), about 83 percent of the 73 POTW/organic pollutant effluent data sets in the table are

comprised of all NC (19 percent) and a mixture of NC & ND (64 percent) values. 

The Agency concludes that POTW performance for metals, ammonia, cyanide, and

organic pollutants is not significantly affected by the bias of effluent data being less than the MLs.
7.0 - Selection of Pollutant Parameters

7-45

Table A-1 – Comparison of 50-POTW Study Removal Estimation Alternatives (Median Percent

Removals)

Pollutant

Parameter

Traditional

Method

 %

Alternative

A

%

Alternative

 B

 %

Alternative

C

 %

Alternative

D

%

Alternative

E

%

Analytical

ML

μg/l

Ammonia 39 40 40 40 39 39 10

Cyanide 70 65 66 60 65 65 20

Antimony 67 47 57 10 57 57 20

Cadmium 90 86 89 37 89 89 5

Chromium 80 76 77 76 76 77 10

Copper 84 80 80 80 79 80 25

Iron 82 82 82 82 80 82 100

Lead 77 48 57 55 57 69 50

Manganese 36 24 24 24 23 23 15

Mercury 90 63 63 60 61 73 0.2

Nickel 51 28 29 32 29 29 40

Silver 88 67 69 69 67 73 2

Tin 43 20 41 39 41 47 30

Zinc 79 77 77 77 76 76 20

Naphthalene 95 95 95 39 95 97 10

Phenol 95 95 96 70 96 97 10
7.0 - Selection of Pollutant Parameters

7-46

Table A-2 - Number of POTWs Retained by Alternative D Data

Conventions

Analyte CAS No.

Total

Number

POTWs

Effluent “All

NC”

Effluent Mix

(NCand ND)

Effluent

“All ND”

Class=Metals, Tech Group=E or S

Aluminum 7429905 31 11 16 4

Antimony 7440360 1 1 0 0

Boron 7440428 6 4 2 0

Cadmium 7440439 6 2 4 0

Calcium 7440702 36 35 1 0

Chromium 7440473 34 23 11 0

Cobalt 7440484 1 0 1 0

Copper 7440508 34 13 17 4

Iron 7439896 43 34 9 0

Lead 7439921 7 2 4 1

Magnesium 7439954 22 22 0 0

Manganese 7439965 40 38 2 0

Mercury 7439976 15 4 11 0

Molybdenum 7439987 2 1 1 0

Nickel 7440020 14 9 5 0

Silver 7440224 17 5 12 0

Sodium 7440235 21 21 0 0

Tin 7440315 3 1 2 0

Titanium 7440326 10 1 9 0

Vanadium 7440622 2 2 0 0

Yttrium 7440655 2 0 2 0

Total 73 14 47 12
Table A-2 (Continued) 7.0 - Selection of Pollutant Parameters

Analyte CAS No.

Total

Number

POTWs

Effluent “All

NC”

Effluent Mix

(NC and ND)

Effluent

“All ND”

7-47

Class=Nonconventional, Tech Group=E or S

Ammonia as N 7664417 35 35 0 0

Total Cyanide 57125 30 27 3 0

Total 65 62 3 0

Class=Organics_LOW, Tech Group=E or S

Bis(2-

ethylhexyl)phthalate

117817 25 6 19 0

Butyl benzyl phthalate 85687 1 0 0 1

Di-n-butyl phthalate 84742 2 0 2 0

Di-n-octyl phthalate 117840 2 0 2 0

Fluoranthene 206440 1 0 1 0

Phenol 108952 7 1 0 6

Total 38 7 24 7

Class=Organics_MED, Tech Group=E or S

Acenaphthene 83329 2 0 1 1

Anthracene 120127 2 0 1 1

Methylene chloride 75092 22 7 15 0

Naphthalene 91203 1 0 0 1

Phenanthrene 85018 2 0 1 1

1,2-Dichlorobenzene 95501 2 0 1 1

1,2-Dichloroethane 107062 2 2 0 0

1,2-Dichloropropane 78875 1 0 0 1

1,2,4-Trichlorobenzene 120821 2 0 2 0

Total 36 9 21 6
Table A-2 (Continued) 7.0 - Selection of Pollutant Parameters

Analyte CAS No.

Total

Number

POTWs

Effluent “All

NC”

Effluent Mix

(NC and ND)

Effluent

“All ND”

7-48

Class=Organics_HIGH, Tech Group=E or S

Benzene 71432 5 0 2 3

Chlorobenzene 108907 1 0 0 1

Chloroform 67663 5 2 3 0

Chloromethane 74873 2 0 2 0

Dichlorodifluoromethane 75718 1 1 0 0

Ethylbenzene 100414 5 0 5 0

Tetrachloroethene 127184 15 4 9 2

Tetrachloromethane 56235 1 1 0 0

Toluene 108883 11 0 9 2

Trans-1,2-Dichloroethene 156605 2 0 2 0

Trichlorethene 79016 10 4 4 2

Vinyl chloride 75014 1 0 1 0

1,1,1,-Trichloroethane 71556 14 2 10 2

Total 347 229 109 9

Source: U.S. EPA, 50-POTW Study, 1982.

Tech Group E = POTWs that achieve effluent BOD5/TSS concentrations less than or equal to 65 mg/l. 

Tech Group S = POTWs that achieve effluent BOD5/TSS concentrations less than or equal to 45 mg/l.

Class Organics_LOW = Organics with Henry’s Law Constant between 10-8 and 10-3. 

Class Organics_MED = Organics with Henry’s Law Constant between 10-3 and 10-1.

Class Organics_HIGH = Organics with Henry’s Law Constant between 10-1 and 1x102.
7.0 - Selection of Pollutant Parameters

7-49

Appendix B

Revised Data Conventions

for the “50-POTW Study” Analytical Data

1. (New) Applied an alpha-numeric naming convention to identify parallel treatment trains

within a POTW. The naming convention is composed of the POTW’s number and a

suffix. For example, POTW 10 has two parallel treatment trains. The applied

convention designates these trains as 10A and 10B. Records associated with treatment

train “A” in POTW 10 all carry the designation 10A. If a POTW has only one

treatment train, then, with one exception, all records for the POTW are identified by the

POTW number. No suffix is applied. In the case of POTW 56, a sampling point is

designated after primary clarification (56A) and after tertiary filtration (56B). Samples

were not collected after the secondary activated sludge treatment unit. The traditional

data conventions – used for the MP&M proposal -- averaged all of the respective

influent and effluent values for parallel treatment systems.

2. (New) Added treatment technology codes and technology flags. Treatment Technology

codes include “AS” for activated sludge, “TF” for trickling filter, “RBC” for rotating

biological contactor, lagoon, and primary clarifier. Some POTWs use a combination of

treatments such as AS + tertiary oxidation ponds. When treatment technologies are

used in combination, the combination is identified. Technology flags are: “P” for

primary treatment; “S” for secondary biological treatment; “E” for equivalent to

secondary biological treatment; and “T” for secondary biological or equivalent

treatment systems with tertiary treatment unit operations.

3. This placeholder ensures consistency between the computer output headings and these

data conventions. (The numbered statements correspond to preliminary drafts of the

revised data conventions. Some data conventions contained in earlier drafts were

mistaken or misplaced in sequence and EPA removed these conventions from

subsequent drafts. However, EPA retained the assigned number sequence because of

reference to these numbers in the computer listings. Thus, this number is effectively

blank.)

4. Converted the units of measure for each pollutant to a common metric.

5. (Revised) Deleted individual data points for a pollutant if supporting records indicated

that one of the following conditions was met (corresponding to key codes 4, 5, 6, and 8

described at the end of this appendix):
7.0 - Selection of Pollutant Parameters

7-50

a. Analytical interference prevented the determination of the presence or

quantification of the pollutant (key code = 4),

b. Analytical interference was indicated, but the pollutant concentration was not

recorded above the concentration reported (key code = 5), 

c. No chemical analysis was conducted or the result of the chemical analysis was

not reported (key code = 6), and

d. The pollutant was qualitatively present but not quantified or confirmed (key

code = 8).

e. (Revised) Deleted the record results from a “right censored” qualitative

method. These records are identified as “greater-than (>) X” where “X” is a

method specific value. This indicator signifies that the recorded measure is the

lower bound of the amount of the pollutant in the sample. The traditional data

conventions – used for the MP&M proposal -- reported “>values” as the

value. (If calculations are based on influent “>values,” then the percent

removals would be lower than they should be. If calculations are based on

effluent “>values,” then the percent removals would be higher than they should

be.)

The revised data conventions delete pollutant concentration data points on an individual

basis, not in pairs. For example, if the influent data point meets one of the previously

identified conditions, it is deleted. Its paired effluent data point is not deleted unless it

too meets one of the conditions. The traditional data conventions deleted data in daily

pairs. 

6. Incorporated the standardized analytical “minimum level” (ML) values for each record.

These values were assigned based on a determination of the analytical method

employed and the precision and accuracy of the 1978 to 1980 analytical methods used

to measure the pollutant.

7. (Revised) Deleted records reported as “< values” that are greater than the ML. This

may occur when samples are diluted to reduce analytical matrix interference. If a

pollutant is not detected in the diluted sample, the resulting ML is multiplied by the

dilution factor. (For data reported as “< values,” this rule initially set the value to the

ML for calculation purposes without considering if the value is greater than the ML. 

For influent value substitutions, the traditional editing rule decreases calculated

performance. For effluent value substitutions, it increases calculated performance.)
7.0 - Selection of Pollutant Parameters

7-51

8. Set equal to the pollutant analytical ML, any remaining pollutant values reported as

non-detect (key codes 1, 3, 1nd 7):

a. Less than the concentration listed (key code = 1),

b. Detected, but not quantified at lower than the concentration listed (key code =

3), and

c. “Not-detected” (key code = 7),

9. For detected or non-censored (NC) values reported as less than the ML, set the value

equal to the ML and report the value as a non-detect.

10. (New) If the pollutant ML is GREATER THAN 20, substituted 0.5xML for influent

and effluent samples if all effluent values are equal to the ML and the value was a nondetect. The following pollutants are excluded from this convention: BOD5

, COD,

O&G, TDS, TOC, Total Solids, and TSS.

11. Retain pollutant data for a POTW if there are at least three (3) influent concentration

values reported and at least one of the reported influent values is measured above the

ML for the pollutant.

12. This placeholder ensures consistency between the computer output headings and these

data conventions. (The numbered statements correspond to preliminary drafts of the

revised data conventions. Some data conventions contained in earlier drafts were

mistaken or misplaced in sequence and EPA removed these conventions from

subsequent drafts. However, EPA retained the assigned number sequence because of

reference to these numbers in the computer listings. Thus, this number is effectively

blank.)

13. (New) Retain POTW treatment trains with secondary biological treatment or

equivalent (as designated by treatment flags “S” or “E”, only if both the effluent BOD5

and TSS average concentrations are less than or equal to 45 mg/l.

14. (Revised) Retain non-negative percent removals that are greater than zero for a given

pollutant where the percent removal = (100)(ave influent - ave effluent)/ave influent.

The traditional data conventions retained zero percent removals. (The medians of these

intermediate values are referred to as Alternative C.)

15. Identify three (overlapping) subsets of POTWs based on the average influent

concentration: 
7.0 - Selection of Pollutant Parameters

7-52

a. (i.) If all effluent values are equal to the ML and the ML is greater than 20 ppb,

retain the pollutant performance (percent removal) if the pollutant influent

average is at least ten times one-half the nominal minimum level [10x( 0.5xML)

= 5xML].

(ii) If all effluent values are equal to the ML and the ML is less than or equal to

20 ppb, retain the pollutant performance (percent removal) if the pollutant

influent average is at least ten times the nominal minimum level (10 x ML). 

b. If the effluent average is greater than the ML, retain the pollutant performance

(percent removal) regardless of the pollutant influent average. 

16. The national POTW/pollutant percent removal is the median of the retained values from

15A and 15B above. (This is referred to as Alternative A.)

17. Modify 15B: If the effluent average is greater than the ML, retain the pollutant

performance (percent removal) if the pollutant influent average is at least two times the

nominal minimum level (2xML).

18. Modify 16: The national POTW/pollutant percent removal is the median of the retained

values from 15A and 17 above. (This is referred to as Alternative B.)

 19. Modify 13: (a) Retain POTW treatment trains with secondary biological treatment (as

designated by treatment flag “S”), only if both the effluent BOD5 and TSS average

concentrations are less than or equal to 45 mg/l. (b) Retain POTW treatment trains

with equivalent to secondary biological treatment (as designated by treatment flag “E”),

only if both the effluent BOD5 and TSS average concentrations are less than or equal to

65 mg/l. (c) The national POTW/pollutant percent removal is the median of the

retained values from 15A and 17 above. (This is referred to as Alternative D.)

 20. Modify 19: Substitute 0.5xML for all data points set equal to the analytical ML. (This

is referred to as Alternative E.) 
7.0 - Selection of Pollutant Parameters

7-53

Description of the Key Codes (See pages 29 & 30, 50-POTW Study) used to qualify analytical results

in the 50-POTW Data Set. 

CODE CONCENTRATION MEANING OF CODE

0 any detected at this concentration

1 any less than this concentration

2 any detected at greater than (>) this

concentration

3 any detected, but not quantified at lower

than this concentration

4 0 analytical interference prevented

determination of the presence or

prevented quantification of the analyte

4 any value >0 analytical interference was present, but

concentration was estimated as this

concentration

5 any analytical interference was present, but

the analyte was not detected above this

concentration 

6 0 no analysis was run or reported

7 0 or blank reported as "not detected"

8 0 analyte was detected, but could not be

quantified

8 any value >0 a pesticide was detected by GC-ECD

at this concentration, but GC-MS did

not confirm the presence of the analyte
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-1

8.0 POLLUTION PREVENTION PRACTICES AND WASTEWATER

TREATMENT TECHNOLOGIES

This section presents an overview of pollution prevention practices and

wastewater treatment technologies in the MP&M industry. Section 8.1 describes pollution

prevention practices, Section 8.2 describes technologies used for the preliminary treatment of

waste streams, and Section 8.3 describes end-of-pipe wastewater treatment and sludge

dewatering technologies. This section discusses the most prevalent technologies in place at

MP&M facilities, including all the technologies used as a basis for the MP&M effluent

guidelines. However, additional technologies may be applicable for some MP&M facilities,

depending on the waste streams generated. Additionally, not all technologies discussed in this

section are applicable to all MP&M sites; the technology applicability is driven by the processes

performed and waste streams generated on site.

8.1 Pollution Prevention Practices

Pollution prevention practices reduce the generation or discharge of pollutants and

therefore potentially reduce treatment or disposal costs. Typical pollution prevention practices

include reducing water use, extending the life of process bath constituents, or adding recycling or

reuse technologies. This section divides pollution prevention practices into three categories. 

Section 8.1.1 discusses flow reduction practices, Section 8.1.2 discusses in-process pollution

prevention technologies, and Section 8.1.3 describes additional methods of pollution prevention.

8.1.1 Flow Reduction Practices

Flow reduction practices are applied to process baths or rinses to reduce the

amount of wastewater discharged. Flow reduction practices consist of optimizing rinse tank

design and configuration and installing flow reduction technologies such as flow restrictors or

timers. The following sections discuss flow reduction practices in greater detail.

8.1.1.1 Rinse Tank Design and Innovative Configurations

Rinsing follows many MP&M unit operations to remove dirt, oil, or chemicals

(i.e., drag-out) remaining on parts or racks from a previous unit operation. Rinsing improves the

quality of the surface finishing process and prevents the contamination of subsequent process

baths. Rinse tank design and rinsing configuration are important factors influencing water usage. 

The key objectives of optimal rinse tank design are to quickly remove drag-out from the part and

to disperse the drag-out throughout the rinse tank.

The MP&M industry uses various rinsing configurations. The use of single

overflow rinse tanks following each process tank is the most inefficient use of rinse water. 

Multiple rinse tanks connected in series (i.e., cascade rinsing) reduce the water needs of a given

rinsing operation by one or more orders of magnitude (i.e., less water is needed to achieve the

same rinsing criterion). Spray rinsing can also be used to reduce water use requirements, but the
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Figure 8-1. Countercurrent Cascade Rinsing

achievable percent reduction of water use is usually less than for countercurrent cascade rinses. 

A description of some of the common rinse types is provided below.

Cascade rinsing

Cascade rinsing is a method of reusing rinse water. Rinse water from one rinsing

operation is plumbed to another, less critical rinsing operation before being discharged to

treatment. Some rinse waters acquire chemical properties, such as low pH, that make them

desirable for reuse in other rinse systems. For example, an acid treatment rinse may be plumbed

to an alkaline treatment rinse, providing both drag-out removal and neutralization. 

Countercurrent Cascade Rinsing

Countercurrent cascade rinsing refers to a series of consecutive rinse tanks which

are plumbed to cause water to flow from one tank to another in the direction opposite of the work

flow. Fresh water flows into the rinse tank located farthest from the process tank and overflows,

in turn, to the rinse tanks closer to the process tank. This technique is termed countercurrent

rinsing, because the work piece and the rinse water move in opposite directions. Over time, the

first rinse becomes contaminated with drag-out and reaches a stable concentration which is lower

than the process solution. The second rinse stabilizes at a lower concentration, which enables

less rinse water to be used than if only one rinse tank were in place. Increasing the number of

countercurrent cascade rinse tanks (three-stage, four-stage, etc.), reduces the amount of water

needed to adequately remove the process solution. Figure 8-1 shows the application of

countercurrent cascade rinsing. 
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 (8-1)

The rinse rate needed to adequately dilute drag-out depends on the concentration

of process chemicals in the drag-out, the concentration of chemicals that can be tolerated in the

final rinse tank before poor rinse results are obtained, and the number of countercurrent cascade

rinse tanks. These factors are expressed in the following equation (2):

where:

Vr = the flow through each rinse stage, gal/min;

Co = the concentration of the contaminant(s) in the initial process bath,

mg/L;

Cf = the tolerable concentration of the contaminant(s) in the final rinse

to give acceptable product cleanliness, mg/L;

n = the number of rinse stages used; and

VD = the drag-out carried into each rinse stage, expressed as a flow,

gal/min.

This mathematical rinsing model is based on complete rinsing (i.e., removal of all

contaminants from the part/fixture) and complete mixing (i.e., homogeneous rinse water). Under

these conditions, each additional rinse stage can reduce rinse water use by 90 percent. These

conditions are not achieved unless there is sufficient residence time and agitation in each rinse

tank. For less efficient rinse systems, each added rinse stage reduces rinse water use by 50 to 75

percent.

Countercurrent cascade rinsing systems have higher capital costs than overflow

rinses and require more space to accommodate the additional rinse tanks. Also, when

countercurrent cascade rinsing is used, the low flow rate through the rinse tanks may not provide

the needed agitation for drag-out removal. In such cases, air or mechanical agitation may be

added to increase rinsing efficiency. 

Drag-out Rinsing

A drag-out rinse is a stagnant rinse, initially filled with fresh water, positioned

immediately after the process tank. Parts are rinsed in drag-out tanks directly after exiting the

process bath. The drag-out rinse collects the majority of the drag-out from the process tank, thus

preventing it from entering the subsequent flowing rinses and therefore reducing pollutant

loadings in those rinses. Gradually, the concentration of process chemicals in the drag-out tank

rises. In the most efficient configuration, a drag-out tank follows a heated process tank that has a

moderate to high evaporation rate. A portion of the fluid in the drag-out tank returns the process
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tank to replace the evaporative loss. The level of fluid in the drag-out tank is maintained by

adding fresh water. Electrolytic recovery of dissolved metals from drag-out tanks is also

common.

Spray Rinsing

For certain part configurations, spray rinsing uses considerably less water than

immersion rinsing. Spray rinsing can be performed in a countercurrent cascade configuration,

further reducing water use. Spray rinsing can enhance draining over a process bath by diluting

and lowering the viscosity of the process fluid film clinging to the parts. 

8.1.1.2 Additional Rinse Design Elements

In addition to rinse configuration, other modifications can be made to the process

line to reduce drag-out of process bath chemicals. For example, air knives and drip tanks reduce

the pollutant loading and amount of rinsewater requiring treatment. Other aspects of good rinse

tank design include positioning the water inlet and discharge points of the tank at opposite

locations in the tank to avoid short-circuiting, using air agitation for better mixing, using a flow

distributor, and using the minimum tank size possible (5). EPA describes several additional rinse

design elements in more detail below.

Air Knives

Air knives are usually installed over a process tank or drip shield and are designed

to remove drag-out by blowing it off the surface of parts and racks. Drag-out is routed back to

the process tank. Air knives are most effective with flat parts and cannot be used to dry surfaces

that passivate or stain due to oxidation. 

Drip Shields

Drip shields are installed between process tanks and rinse tanks to recover process

fluid dripping from racks and barrels that would otherwise fall into rinse tanks or onto the floor. 

Often, drip shields are an inclined piece of polypropylene or other material which is inert to the

metal finishing process. 

Drip Tanks

Drip tanks are similar to drag-out tanks except they are not filled with water. 

Parts exiting a process bath are held over the drip tank and the process fluid that drips from the

parts is collected in the tank. When enough fluid is collected in the drip tank, the fluid is

returned to the process tank. 
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Long Dwell Time

Automatic lines can be programmed to include optimum drip times. Long dwell

times over the process tank reduce the volume of drag-out reaching the rinsing system. On

manual lines, racks can be hung on bars over process baths to allow time to drip. Barrels can be

rotated over the process bath to enhance drainage. Increases in drip time may be unsuitable for

surfaces that can be oxidized or stained by exposure to air.

8.1.1.3 Rinse Water Use Control

Facilities can reduce water use by coordinating and closely monitoring rinse water

requirements (e.g., rinse water use is optimized based on drag-out rates so that the rinse criterion

is consistently achieved). Matching water use to rinse water requirements optimizes the quantity

of rinse water used for a given work load and tank arrangement (5). Inadequate control of wateruse negates the benefits of using multiple rinse tanks or employing other water conservation

practices and results in a high water usage. 

Many sites use some form of rinse water control. The four most common

methods are flow restrictors (these can be used with other methods to regulate the rate at which

water is dispensed), manual control (i.e., turning water valves on and off as needed), conductivity

controls, and timer rinse controls. These are discussed below.

Flow Restrictors

A flow restrictor prevents the flow in a pipe from exceeding a predetermined flow

rate. Flow restrictors are commonly installed on a rinse tank’s water inlet. These devices contain

an elastomer washer which flexes under pressure to maintain a constant water flow regardless of

pressure. Flow restrictors can maintain a wide range of flow rates, from less than 0.1 gal/min to

more than 10 gal/min. As a stand-alone device, a flow restrictor provides a constant water flow. 

As such, for intermittent rinsing operations, a flow restrictor does not coordinate the rinse flow

with drag-out introduction. Precise control with intermittent operations typically requires a

combination of flow restrictors and rinse timers. However, for continuous rinsing (e.g.,

continuous electroplating machines), flow restrictors may be adequate for good water use control. 

Conductivity Meters

Conductivity probes measure the conductivity of water in a rinse tank to regulate

the flow of fresh rinse water into the rinse system. Conductivity controllers consist of a

controller, a meter with adjustable set points, a probe that is placed in the rinse tank, and a

solenoid valve. As parts are rinsed, dissolved solids enter the water in the rinse tank, raising the

conductivity of the water. When conductivity reaches a set point where the bath can no longer

provide effective rinsing, the solenoid valve opens to allow make-up water to enter the tank. 

When the conductivity falls below the set point, the valve closes to discontinue the make-up

water flow.
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In theory, conductivity control of rinse flow is a precise method of maintaining

optimum rinsing conditions in intermittently used rinse operations. In practice, conductivity

controllers work best with deionized rinse water. Incoming water conductivity may vary day-today and season-to-season, which forces frequent set point adjustments. In addition, suspended

solids and nonionic contaminants (e.g., oil) can cause inadequate rinsing and are not detected by

the conductivity probe.

Rinse Timers

Rinse timers are electronic devices that control a solenoid valve. The timer

usually consists of a button that, when pressed, opens the valve for a predetermined length of

time, usually from 1 to 99 minutes. After the time period has expired, the valve is automatically

closed. The timer may be activated either manually by the operator or automatically by the

action of racks or hoists. Automatic rinse timers are generally preferred for intermittent rinses

since they eliminate operator error. Rinse timers installed in conjunction with flow restrictors

can provide precise control when the incoming water pressure may rise and fall. Rinse timers are

less effective in continuous or nearly continuous rinse operations (e.g., continuous electroplating

machines).

8.1.1.4 Pollution Prevention for Process Baths

Facilities can also implement pollution prevention technologies for process baths

to reduce the pollutant loadings and therefore the amount of rinse water required. EPA gives

several examples of pollution prevention technologies for process baths below.

Temperature

Temperature and viscosity are inversely related; therefore, operating at the highest

possible bath temperature will lower viscosity and reduce drag-out.

Lower Concentration

Operating at the lowest possible concentration reduces the mass of chemicals in a

given volume of drag-out. Also, viscosity and concentration are directly related; therefore, lower

process bath concentration will result in lower viscosity and less drag-out volume. Contaminants

and other process bath impurities should be minimized, if possible.

Wetting Agents

Wetting agents or surfactants may be added to some process baths to reduce

viscosity and surface tension, thereby significantly reducing drag-out.
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8.1.2 In-Process Pollution Prevention Technologies

This section describes in-process pollution prevention technologies used in the

MP&M industry. Not all technologies discussed in this section are applicable to all MP&M

sites. The pollution prevention practices that are included in the MP&M technology options are

listed in Section 9.0. 

In-process pollution prevention technologies can be applied to process baths or

rinses. Process baths become contaminated with impurities that affect their performance. The

sources of process bath contamination include: (1) breakdown of process chemicals; (2) buildup

of byproducts (e.g., carbonates); (3) contamination from impurities in make-up water, chemicals,

or anodes; (4) corrosion of parts, racks, tanks, heating coils, etc.; (5) drag-in of chemicals; (6)

errors in bath additions; and (7) airborne particles entering the tank. If not properly maintained,

process baths eventually become unusable and require disposal. Regeneration and maintenance

techniques help keep baths in good operating condition, thereby extending the useful lives of

process solutions. Use of these technologies reduces the pollutant loading to the wastewater

treatment system, which in turn reduces wastewater treatment chemical purchases and sludge

disposal costs.

This section describes the following technologies:

C Activated carbon adsorption;

C Carbonate freezing;

C Centrifugation and pasteurization of machining coolants;

C Centrifugation and recycling of painting water curtains;

C Electrodialysis;

C Electrolytic recovery;

C Evaporation;

C Filtration;

C Ion exchange; and

C Reverse osmosis.

8.1.2.1 Activated Carbon Adsorption

Activated carbon adsorption of electroplating baths is a common method of

removing organic contaminants. Process solution flows through a filter where the carbon

adsorbs organic impurities that result from the presence of oils or cleaners from the breakdown of

bath constituents. Carbon adsorption can be used on either a continuous or batch basis,

depending on the site’s preference. Carbon treatment is most commonly applied to nickel,

copper, zinc, and cadmium electroplating but can also be used to recycle paint curtain

wastewater.
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8.1.2.2 Carbonate “Freezing”

Carbonate “freezing” removes excessive carbonate buildup by forming carbonate

salt crystals at a low temperature. This process is most often applied to electroplating baths

formulated with sodium cyanide. Carbonates build up in the process bath by the breakdown of

cyanide (especially at high temperatures) and the adsorption of carbon dioxide from the air. An

excessive carbonate concentration reduces the quality of many metal finishing operations.

Carbonate “freezing” takes advantage of the low solubility of carbonate salts in the sodium

cyanide bath. The method lowers the bath temperature to approximately 26°F (-3°C), at which

point hydrated salt (Na2CO3•10H2O) crystallizes out of solution. The crystallized carbonate can

be removed by decanting the fluid into another tank or by filtration.

8.1.2.3 Centrifugation and Pasteurization of Machining Coolants

Most machining coolants consist of water-soluble oil in water. The water-soluble

coolant is typically pumped through a sump, over the machining tool and part during machining,

and back to the sump. Over a period of time, coolant becomes ineffective, or spent, for one or

more of the following reasons:

C The concentration of suspended solids in the coolant begins to inhibit

performance; 

C Nonemulsified, or “tramp”, oil collects on the surface of the coolant;

C The coolant becomes rancid due to microbial growth; or

C Coolant additives are consumed by drag out and organic breakdown, thus

reducing corrosion prevention and lubrication properties.

Machining coolant can be recycled using a centrifugal separator and

pasteurization unit. Centrifugation removes the solids from the coolant to extend its usable life. 

The separator is a rotating chamber that uses centrifugal force to push the coolant through a mesh

chamber, leaving behind the contaminants. Sludge is scraped from the centrifuge and collected

in a sludge hopper. Some high speed centrifuges can also perform liquid - liquid separation for

the removal of tramp oils. The coolant is pasteurized after separation to kill the microorganisms

that cause bacterial growth. Bacterial growth can also be controlled by addition of a biocide.

Figure 8-2 shows a diagram of a typical machine coolant recycling system.
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Figure 8-2. Machine Coolant Recyclying System

Centrifugal separators are very reliable and require only routine maintenance, such

as periodic cleaning and removal of accumulated solids. Flow rate is the primary operating

factor to control. The sludge generated from this technology is commonly classified as a

hazardous waste, based on the metal type processed and the amount of metal that dissolves into

the coolant. The sludge is typically contract hauled for treatment and disposal.

Coolant recycling is most effective when sites minimize the number of different

coolants used on site and use a centralized coolant recycling system. However, some sites may

not be able to use a single recycling system because of multiple coolant types required by product

or customer specifications. In this case, sites may need to purchase dedicated coolant recycling

systems for each type of coolant used. 

Centrifugation and pasteurization can be used along with oil skimming and

biocide addition to reduce coolant discharge and pollutant generation at the source. Oil

skimming using a vertical belt system removes large amounts of tramp hydraulic oils floating on

the surface of the machine coolant. Oil skimming and biocide addition can further extend the

life of water-soluble coolant, thereby reducing the amount of coolant and wastewater requiring

treatment and disposal, and minimizing the amount of fresh coolant purchased. 

8.1.2.4 Centrifugation and Recycling of Painting Water Curtains

Water curtains are a continuous flow of water behind the part being spray painted

in a paint booth. The water traps paint overspray and is continuously recirculated in the paint

curtain until the solids content in the wastewater necessitates either in-process treatment and

recycling or discharge. Centrifugal separators remove the solids and recycle the water curtain,

eliminating the need for discharge. In this system, wastewater is pumped to a holding tank, then

through the centrifugal separator, which separates the solids from the wastewater (see section
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Figure 8-3. Centrifugation and Recycling of Painting Water Curtains

8.1.2.3). Solids are contract hauled for off-site disposal, while the treated wastewater is returned

to the paint booth. Detactifiers may be added before centrifugation to increase the solid

separation efficiency.

Centrifugation of the paint curtain proceeds until all wastewater is treated and

only sludge remains in the sump. The sludge in the water curtain sump must be removed either

manually, with a sludge pump, or by a vacuum truck. After the sludge has been removed and the

wastewater has been treated through the centrifuge, the wastewater from the holding tank is

pumped back into the water curtain sump. Make-up water is added to compensate for

evaporation. Using this procedure, the paint curtain water can be continuously recycled. Figure

8-3 shows a flow diagram of a typical paint curtain centrifugation and recycling system. 

Wastewater from painting water curtains commonly contains organic pollutants as

well as certain metals. Eliminating the discharge of wastewater from painting water curtains may

eliminate the need for an end-of-pipe treatment step for organic pollutants at certain sites. Also,

if a site generates only painting wastewater and continuously recycles the wastewater, the site

would not need end-of-pipe wastewater treatment. 

As discussed in Section 8.1.2.3, centrifugal separators are very reliable and

require only routine maintenance. Flow rate is the primary operating factor to control. One

disadvantage of this technology is that it may not be economically feasible for sites generating

only a small amount of paint curtain wastewater. Sites that have multiple sumps can use portable

centrifuges.
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Figure 8-4. Electrodialysis Cell

The sludge generated from painting water curtains is commonly classified as a

hazardous waste, based on the type of paint used, and is typically contract hauled for treatment

and disposal.

8.1.2.5 Electrodialysis

Electrodialysis is a membrane technology used to remove impurities from process

solutions. A direct current is applied across a series of alternating anion and cation exchange

membranes to remove dissolved metal salts and other ionic constituents from solutions.

An electrodialysis unit consists of a rectifier and a membrane stack. The rectifier

converts alternating current to direct current. The stack consists of alternating anion- and cationspecific membranes which form compartments. As the feed stream enters the unit, ions move

across the electrodialysis membranes, forming a concentrated stream and a deionized stream.

When the compartments are filled, a direct current is applied across each membrane in the stack. 

Cations traverse one cation-specific membrane in the direction of the cathode and are trapped in

that concentrate compartment by the next membrane, which is anion-specific. Anions from the

neighboring compartment traverse the anion-specific membrane in the direction of the anode,

joining the cations, and are likewise trapped in the concentrate compartment by the next cationspecific membrane. In this way, the feed stream is depleted of ions, and anions and cations are

trapped in each concentrate compartment. Electrodialysis is typically used to remove metal ions

from electroplating wastewater. Figure 8-4 shows a diagram of an electrodialysis cell.

8.1.2.6 Electrolytic Recovery

Electrolytic recovery is an electrochemical process used to recover metals from

many types of process solutions and rinses, such as electroplating rinse waters and baths. 
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Electrolytic recovery removes metal ions from a waste stream by processing the stream in an

electrolytic cell, which consists of a closely spaced anode and cathode. Commercial equipment

consists of one or more cells, a transfer pump, and a rectifier. Current is applied across the cell

and metal cations are deposited on the cathodes. The waste stream is usually recirculated

through the cell from a separate tank, such as a drag-out recovery rinse. 

Electrolytic recovery is typically applied to solutions containing either nickel,

copper, precious metals, or cadmium. Chromium cannot be electrolytically recovered because it

exists primarily in anionic forms such as dichromate. Aluminum is also a poor candidate for

electrolytic recovery. Drag-out recovery rinses and ion-exchange regenerant are solutions that

are commonly processed using electrolytic recovery. Some solutions require pH adjustment prior

to electrolytic recovery. Acidic, metal-rich, cation regenerant is an excellent candidate stream for

electrolytic recovery and is often electrolytically recovered without pH adjustment. In some

cases, when the target metal concentration is reached, the waste stream may be reused as cation

regenerant.

The capacity of electrolytic recovery equipment depends on the total cathode area

and the maximum rated output of the rectifier. Commercial units are available with a cathode

area ranging from 1 ft2 to 100 ft2 or larger, and an output of 10 to 1,000 amperes or more. 

Theoretical electrolytic recovery rates are determined by Faraday’s law which states the amount

of chemical change produced by an electric current is proportional to the quantity of electricity

used. Theoretical recovery rates range from 1.09 grams/amp-hour for nickel to 7.35 grams/amphour for monovalent gold. Actual rates are usually much lower and depend on the metal

concentration in the waste stream. At concentrations under 100 mg/L, electrolytic recovery rates

may be below 10 percent of the theoretical maximum.

Various types of cathodes are used in electrolytic recovery units, depending

mainly on the concentration of metal in the waste stream. Cathodes are often classified by their

surface area. Flat-plate cathodes have the lowest surface area and are used only for recovering

metal from metal-rich waste streams (usually 1,000 to 20,000 mg/L of metal). Reticulate

cathodes, which have a metallized woven fiber design, have a surface area ten times greater than

their apparent area. These cathodes are effective over a wide range of metal concentrations but

are typically used where the dissolved metal concentration is below 100 mg/L. Carbon and

graphite cathodes have the highest surface area per unit of apparent area. Their use is usually

restricted to metal concentrations below 1,000 mg/L. 

Dissolved metals in electrolytes can be recovered to low levels (<5 mg/L) using

reticulate or carbon cathodes. In practice, however, the target concentration for most applications

is 50 to 250 mg/L or higher because of the time and energy required to achieve concentrations

less than 100 mg/L. With flat-plate cathodes, the target concentration is usually above 500 mg/L,

because plating efficiency drops as concentration falls. Plating time required to lower the

concentration of a pollutant from 100 to 10 mg/L can be several times longer than that required

to lower the concentration from 10,000 mg/L to 100 mg/L. Also, unit energy costs (measured in

dollars per pound of metal recovered) increase substantially at lower metal concentrations.
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Labor requirements are relatively low for electrolytic recovery. Units recovering

metal from drag-out recovery tanks may only require occasional cleaning and maintenance. 

Units treating batch discharges from ion-exchange units require more labor due to the higher

metal content of the solution and the resultant increase in cathode loading frequency. Energy

costs for this technology can be high, and, in some cases, exceed the recovery value of the metal. 

Energy requirements depend on several factors, including required voltage, rectifier efficiency,

and current efficiency. In addition, from an energy standpoint, electrolytic recovery removes

metals from concentrated solutions more efficiently than from dilute solutions. Electrode

replacement costs may be significant for units using disposable cathodes, especially for high

metal recovery rates. However, if electrodes are constructed properly, cathodes and anodes may

last more than five years for most applications. 

Numerous vendors offer electrolytic recovery technology. The technology is

applicable to a wide range of processes, drag-out rinses, and ion-exchange regenerants due to the

diversity of materials and configurations available for anodes and cathodes. Electrolytic recovery

is not applicable to flowing rinses due to the lower metal concentrations and the extended time

required for metal recovery. In most cases, this technology cannot cost-effectively remove

dissolved metals to concentrations required for discharge to POTWs or surface waters.

8.1.2.7 Evaporation

Evaporation is a common chemical recovery technology. There are two basic

types of evaporators: atmospheric and vacuum. Atmospheric evaporators are more prevalent

and are relatively inexpensive to purchase and easy to operate. Vacuum evaporators are

mechanically more sophisticated and are more energy-efficient. Vacuum evaporators are

typically used when evaporation rates greater than 50 to 70 gallons per hour are required. There

are two typical methods of in-process evaporation and reuse: 1) evaporate the water and then

condense the water for reuse in baths and rinses, and 2) evaporate the water and reuse the

concentrate (i.e., the process solution that remains after water is evaporated) in process baths. 

Reusing the condensate is more common.

8.1.2.8 Filtration

Filtration removes suspended solids from surface finishing solutions. Suspended

solids in surface finishing solutions may cause roughness and burning of deposits. Filtration uses

various types of equipment, the most common of which are cartridge filters, precoat

diatomaceous earth filters, sand, and multimedia filters. Cartridge filters are available with either

in-tank or external configurations. The in-tank units are used mostly for small tanks and the

external units for larger tanks. Most cartridges are disposable; however, washable and reusable

filters are available, which further reduce waste generation. Precoat, sand, and multimedia filters

are used mostly for large tanks. The filter media used depends on the chemical composition of

the bath. All filtration systems are sized based on solids loading and the required flow rate.
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Figure 8-5. Membrane Filtration Unit

Membrane filtration can also be used to remove oils and metals from process

baths or rinses. Membrane filters can be used to recycle paint curtain or machine coolant

wastewater and are typically used to recover and recycle electrophoretic painting (“e-coat”)

solutions. Membrane filtration is a pressure-driven process used to separate solution components

based on molecular size and shape. Solvent and small solutes can pass through the membrane

while the membrane retains and collects larger compounds as a concentrated waste stream. The

cleaner permeate can be reused in the process. Figure 8-5 shows a typical membrane filtration

unit.
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Figure 8-6. Ion Exchange

8.1.2.9 Ion Exchange (in-process)

Ion exchange is a commonly used technology within the MP&M industry. In

addition to water recycling and chemical recovery applications, ion exchange is used to soften or

deionize raw water for process solutions. Figure 8-6 shows a typical ion exchange system.

Ion exchange is a reversible chemical reaction that exchanges ions in a feed

stream for ions of like charge on the surface of an ion-exchange resin. Resins are broadly

divided into cationic or anionic types. Typical cation resins exchange H+ for other cations, while

anion resins exchange OH- for other anions. 
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In practice, a feed stream passes through a column, which holds the resin. The

feed stream is usually either dilute rinse water (in-process ion exchange) or treated wastewater

(end-of-pipe ion exchange). Often, prior to ion-exchange treatment, the feed stream passes

through a cartridge filter and a carbon filter to remove suspended solids and organics that foul the

resin bed. The exchange process continues until the capacity of the resin is reached (i.e., an

exchange has occurred at all the resin sites). A regenerant solution is then passed through the

column. For cation resins, the regenerant is an acid, and the H+ ions replace the cations captured

from the feed stream. For anion resins, the regenerant is a base, and OH- ions replace the anions

captured from the feed stream. The metals concentration is much higher in the regenerant than in

the feed stream; therefore, the ion-exchange process not only separates the metals from the

wastestream but also results in a more concentrated wastestream.

Ion exchange is used for water recycling and/or metal recovery. For water

recycling, cation and anion columns are placed in series. The feed stream is deionized and the

product water is reused for rinsing. Often, closed-loop rinsing is achieved. The regenerant from

the cation column contains metal ions, which can be recovered in elemental form via electrolytic

recovery (see Section 8.1.2.6). The anion regenerant is typically discharged to wastewater

treatment. This type of ion exchange is used to recycle relatively dilute rinse streams. Generally,

the total dissolved solids (TDS) concentration of such streams must be below 500 mg/L to

maintain an efficient regeneration frequency. Reducing drag-out can enhance the efficiency of the

recovery process. Effluent TDS concentrations of 2 mg/L or less are typical.

When metal recovery is the only objective, a single or double cation column unit

containing selective resin is used. These resins attract divalent cations while allowing

monovalent cations to pass, a process usually called metal scavenging. This technology is

efficient if the metal ions being scavenged are the primary source of ions in the stream. Ion

exchange provides effective metals recovery even when the metal content of the stream is only a

small fraction of the TDS present in the stream, making scavenging suitable over a wider range

of TDS than water recycling. Scavenging also provides a highly concentrated regenerant,

particularly suitable for electrolytic recovery (see Section 8.1.2.6). Water recycling using this ion

exchange configuration is not possible since only some of the cations and none of the anions are

removed. Standard units typically achieve effluent metal concentrations of under 0.5 mg/L. 

Many process wastewaters are excellent candidates for ion exchange, including

the rinse water from plating processes of chromium, copper, cadmium, gold, lead, nickel, tin, tinlead, and zinc. Ion exchange resins are usually regenerated using inexpensive chemicals such as

sulfuric acid and sodium hydroxide. Gold-bearing resins are difficult to regenerate and

frequently require incineration to recover the gold content. Lead is also difficult to recover from

ion exchange resins. Methane sulfonic acid and fluoboric acid (usually not suitable for

electrolytic recovery) are effective regenerants for lead ion exchange but are very expensive. 

Cyanide rinse waters are amenable to ion exchange; cation resins are capable of breaking the

metal-cyanide complex and the cyanide is removed in the anion column. The metals in the

cation regenerant can be electrolytically recovered and the cyanide present in the anion

regenerant can be returned to the process or discharged to treatment.
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Ion-exchange equipment ranges from small, manual, single-column units to multicolumn, highly automated units. Two sets of columns are necessary for continuous treatment;

one set receives the wastewater flow while the other set is being regenerated. Thus, two-column

metal scavenging and four-column deionizing systems are common. Automatic systems direct

the wastewater flow and initiate regeneration with little or no operator involvement.

The labor requirements for ion exchange depend on the automation level of the

equipment. Manual systems can have significant labor costs associated with preparing,

transporting, and disposing of regenerants. Automatic systems require far less labor. Resins

need to be replaced periodically due to organic contamination, resin oxidation, and fouling from

suspended solids. This process can be hastened by misuse, accidents, or poor engineering. 

Equipment size is based on flow rate and concentration. Resin capacity varies but

often ranges from 1 to 2 lbs/ft3. Flow rates may range from 1 to 20 or more gpm. Columns are

typically sized to handle wastewater flow for at least a period of time equal to that required for

regeneration. Automatic systems are sized to provide continuous treatment. Regeneration

volume typically ranges from 2 to 4 resin bed volumes of dilute acid or caustic. Concentrations

of feed stream contaminants generally range from 10 to 20 g/L. 

8.1.2.10 Reverse Osmosis

Reverse osmosis is a membrane separation technology used by the MP&M

industry for chemical recovery. Dilute rinse water is pumped to the surface of the reverse

osmosis membrane at pressures of 400 to 1,000 pounds per square inch gauge (psig). The

membrane separates the feed stream into a reject stream and a permeate. The reject stream,

containing most of the dissolved solids in the feed stream, is deflected from the membrane while

the permeate passes through. Reverse osmosis membranes reject more than 99 percent of

multivalent ions and 90 to 96 percent of monovalent ions, in addition to organics and nonionic

dissolved solids. The permeate stream is usually of sufficient quality to be recycled as rinse

water, despite the small percentage of monovalent ions (commonly potassium, sodium and

chloride) that pass through the membrane. Reverse osmosis equipment is similar to the

equipment shown in Figure 8-5.

A sufficiently concentrated reject stream can be returned directly to the process

bath. The reject stream concentration can be increased if the stream is recycled through the unit

more than once or by increasing the feed pressure. In multiple-stage units containing more than

one membrane chamber, the reject stream from the first chamber is routed to the second, and so

on. The combined reject streams from multistage units may, in some cases, have high enough

concentrations to be returned directly to the bath. 

The capacity of reverse osmosis equipment is generally measured in flow volume,

and is determined by the membrane surface area and operating pressure. Generally, increasing

the surface area of the membrane increases the capacity. Operating at higher pressures increases
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the permeate flow volume per unit membrane area (also called the flux). Reject stream

concentration increases with pressure and decreases as flow volume increases. 

Facilities may need to prefilter and pretreat the feed stream to lengthen membrane

life or reduce the frequency of fouling; filtration to remove suspended solids is usually necessary. 

Adjusting pH may prevent precipitation as the feed stream is concentrated, but it may make the

concentrate unfit to return to the process bath.

Reverse osmosis is most applicable to electroplating rinse waters, including

electroplating of Watts nickel, bright nickel, brass cyanide, copper cyanide, and zinc cyanide.

This technology can treat TDS concentrations of up to 1,000 mg/L. Permeate TDS

concentrations of 250 mg/L or less are typical, and the dissolved solids are mostly common

monovalent ions, allowing the permeate stream to be reused in many rinsing operations. 

The maximum achievable reject stream concentration for basic reverse osmosis

equipment is approximately 20,000 mg/L TDS. Multipass and multistage units achieve

concentrations of 30,000 mg/L TDS or higher. If the reject stream is acceptable to return directly

to the process bath and the permeate is recycled as rinse water, a closed loop is created. 

However, returning the reject stream directly to the bath is uncommon because the concentration

is often too low. In cases where the reject stream concentration is not high enough to return it to

the bath, it can be concentrated with an evaporator, electrolytically recovered, or treated

conventionally (e.g., with chemical precipitation). When evaporators are used, however, reverse

osmosis loses its low-energy advantage over other in-process reuse and recovery technologies. 

When both technologies include an electrolytic recovery unit, reverse osmosis

often has a higher capital cost than ion exchange. As end-of-pipe treatment, reverse osmosis and

ion exchange both remove similar quantities of metals; however, reverse osmosis may allow for

more water recycling. During reverse osmosis, energy is consumed only by pumps. In most

cases, water is recycled; in some cases, a closed loop is possible. Compared to ion exchange,

reverse osmosis can treat somewhat higher feed stream concentrations. The concentration of

reverse osmosis reject streams are near or higher than that of ion-exchange regenerants. Both are

less effective in handling oxidizing chemistries or feed streams high in organics and total

suspended solids (TSS). Ion-exchange effluent generally has a lower TDS concentration than

reverse osmosis permeate and can be recycled in most rinses. 

For most applications, reverse osmosis membranes last for one to five years,

although they are susceptible to fouling from organics, suspended solids, or misuse. Reverse

osmosis units may have instrumentation that indicates the condition of the membrane by

measuring the flux. If the membrane fouls or clogs, the flux rate drops, indicating that the

membrane should be cleaned. Labor associated with operating reverse osmosis equipment is for

periodic membrane cleaning. Membrane and pump replacement are the primary maintenance

items. 
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8.1.3 Other Types of Pollution Prevention Practices

Many other types of pollution prevention practices are performed at MP&M

facilities including the following: training and supervision; production planning; process or

equipment modification; raw material and product substitution or elimination; loss prevention

and housekeeping; waste segregation and separation; and closed-loop recycling. EPA describes

each of these practices below. Some of these practices may be elements of an Environmental

Management System (EMS).

Training and Supervision. Training and supervision ensure that employees are

aware of, understand, and support the company’s pollution prevention goals. Effective training

programs translate these goals into practical information that enables employees to minimize

waste generation by properly and efficiently using tools, supplies, equipment, and materials.

Production Planning. Production planning can minimize the number of process

operation steps and eliminate unnecessary procedures (e.g., planning production can eliminate

additional cleaning steps between process operations).

Process or Equipment Modification. Sites can modify processes and equipment

to minimize the amount of waste generated (e.g., changing rack configuration to reduce dragout). 

Raw Material and Product Substitution or Elimination. Where possible, sites

should replace toxic or hazardous raw materials or products with other materials that produce

less waste and/or less toxic waste (e.g., replacing chromium-bearing solutions with

nonchromium-bearing and less toxic solutions, or consolidating types of cleaning solutions and

machining coolants).

Loss Prevention and Housekeeping. Loss prevention and housekeeping

includes performing preventive maintenance and managing equipment and materials to minimize

leaks, spills, evaporative losses, and other releases (e.g., inspecting the integrity of tanks on a

regular basis; using chemical analyses instead of elapsed time or number of parts processed as

the basis for disposal of a solution).

Waste Segregation and Separation. Sites should avoid mixing different types

of wastes or mixing hazardous wastes with nonhazardous wastes. Similarly, sites should not mix

recyclable materials with noncompatible materials or wastes. For example, MP&M facilities can

segregate scrap metal by metal type, separate cyanide-bearing wastewater for preliminary

treatment, and segregate coolants for recycling or treatment.

Closed-Loop Recycling. MP&M sites can recover and reuse some process

streams. For example, some sites can use ion exchange to recover metal from electroplating

rinse water, the rinsewater can be reused, and the regenerant solution can be used as solution

make-up. 
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8.2 Preliminary Treatment of Segregated Wastewater Streams

Preliminary treatment systems reduce pollutant loadings in segregated waste

streams prior to end-of-pipe treatment. Wastewater containing pollutants such as cyanide,

hexavalent chromium, oil and grease, or chelated metals inhibit the performance of end-of-pipe

treatment systems and require preliminary treatment. Proper segregation and treatment of these

streams is critical for the successful treatment of MP&M wastewater. Highly concentrated

metal-bearing wastewater may also be treated to reduce metal concentrations before end-of-pipe

treatment. This section describes the following wastewater streams that typically undergo

preliminary treatment at MP&M facilities:

C Chromium-bearing wastewater;

C Concentrated metal-bearing wastewater;

C Cyanide-bearing wastewater;

C Chelated metal-bearing wastewater; and 

C Oil-bearing wastewater.

8.2.1 Chromium-Bearing Wastewater

MP&M facilities generate hexavalent-chromium-bearing wastewater from acid

treatment, anodizing, conversion coating, and electroplating operations and rinses. Hexavalent

chromium exists in an ionic form and does not form a metal hydroxide; therefore, this

wastewater is not treated directly by chemical precipitation and sedimentation. The wastewater

requires preliminary chemical treatment to reduce the hexavalent chromium to trivalent

chromium. The trivalent chromium can then be removed by chemical precipitation and

sedimentation. The chemical reduction process is discussed below. Figure 8-7 presents a

process flow diagram of a continuous chromium reduction system.

Reduction is a chemical reaction in which electrons are transferred from one

chemical (the reducing agent) to the chemical being reduced. Sulfur dioxide, sodium bisulfite,

sodium metabisulfite, and ferrous sulfate form strong reducing agents in water. MP&M facilities

use these reducing agents to reduce hexavalent chromium to the trivalent form, which allows the

metal to be removed from solution by subsequent chemical precipitation. 

Sodium metabisulfite, sodium bisulfite, and sulfur dioxide are the most widely

used reducing agents at MP&M sites. Below is an equation showing the sulfur dioxide reaction

(reduction using other reagents is chemically similar):

(8-2)
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Figure 8-7. Chemical Reduction of Hexavalent Chromium

An operating pH of between 2 and 3 is normal for chromium reduction. At pH

levels above 5, the reduction rate is slow, and oxidizing agents such as dissolved oxygen and

ferric iron interfere with the reduction process by consuming the reducing agent.

Typically, the chemicals are retained in a reaction tank for 45 minutes. The tank

is equipped with pH and oxidation-reduction potential (ORP) controls. Sulfuric acid is added to

maintain a pH of approximately 2, and a reducing agent is metered to the reaction tank to

maintain the ORP at 250 to 300 millivolts. 

Chemical reduction of hexavalent chromium is a proven technology that is widely

used at MP&M sites. Operation at ambient conditions requires little energy, and the process is

well suited to automatic control. For high concentrations of chromium, treatment chemical costs

may be significant. 

Maintenance of chemical reduction systems consists of sludge removal, the

frequency of which depends on the concentration of contaminants. There may also be small

amounts of sludge generated due to minor shifts in the solubility of the contaminants (e.g., iron

hydroxides). This sludge can be removed by the sludge-handling equipment associated with the

chemical precipitation system.
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8.2.2 Concentrated Metal-Bearing Wastewater

Concentrated metal-bearing wastewater from spent process solutions can be

slowly metered to the end-of-pipe chemical precipitation system and commingled with other

facility wastewater or batch treated. Some facilities send concentrated metal-bearing wastewater

for off-site treatment rather than treating the wastewater on site. Batch treatment of concentrated

metal-bearing wastewater provides better control of the treatment system (e.g., the treatment

chemicals can be better tailored to the specific solution being treated), better treatment of

difficult-to-treat materials (e.g., photo resist-bearing wastewater), and potential recovery of

metals from the sludge. With batch treatment, effluent from the batch treatment tank is typically

discharged to the end-of-pipe treatment system for additional polishing. 

Batch chemical precipitation of concentrated metal-bearing wastewater typically

occurs in a single stirred tank, where a precipitating agent (e.g., sodium hydroxide, lime, sodium

sulfide) is added to create an insoluble metal hydroxide or sulfide complex. Following

precipitate formation, a polyelectrolyte is added to flocculate the metal hydroxide or metal

sulfide particles into larger clumps that will settle to the bottom of the reaction tank following

mixing. Clarified effluent from the batch tank is discharged to the end-of-pipe treatment system

and the settled sludge, typically containing only one type of metal, is transferred offsite for metals

recovery.

8.2.3 Cyanide-Bearing Wastewater

Plating and cleaning wastewater may contain significant amounts of cyanide,

which should be destroyed through preliminary treatment. In addition to its toxicity, cyanide

forms complexes with metals that prohibit subsequent removal in chemical precipitation systems.

Cyanide is typically destroyed using alkaline chlorination with sodium hypochlorite or chlorine

gas or by ozone oxidation. EPA describes these two processes below.

8.2.3.1 Alkaline Chlorination

Cyanide destruction through alkaline chlorination is widely used in industrial

wastewater treatment. Chlorine is typically used as either chlorine gas or sodium hypochlorite

(i.e., bleach). This process is shown by the following two-step chemical reaction:

(8-3)

(8-4)

Figure 8-8 presents a process flow diagram showing alkaline chlorination of cyanide.
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Figure 8-8. Cyanide Destruction Through Alkaline Chlorination

The alkaline chlorination process oxidizes cyanides to carbon dioxide and

nitrogen. The equipment often consists of an equalization tank followed by two continuous

reaction tanks, although the batch reaction can be conducted in a single tank. Each tank has an

electronic controller to monitor and maintain the required pH and ORP. To oxidize cyanides to

cyanates, chlorine or sodium hypochlorite is metered to the reaction tank as necessary to maintain

the ORP at 350 to 400 millivolts, and aqueous sodium hydroxide is added to maintain a pH of 10

to 11. In the second reaction tank, the ORP and the pH level are typically maintained at

600 millivolts and 8 to 9, respectively, to oxidize cyanate to carbon dioxide and nitrogen. Each

reaction tank has a chemical mixer designed to provide approximately one turnover per minute. 

The batch process is usually conducted by using two tanks, one to collect water over a specified

time period and one to treat an accumulated batch. If concentrated wastes are frequently

dumped, another tank may be required to equalize the flow to the treatment tank. When the

holding tank is full, the liquid is transferred to the reaction tank for treatment. 

Alkaline chlorination can be performed at ambient temperature, can be

automatically controlled at relatively low cost, and can achieve effluent concentrations of free

cyanide that are below the detection limit. Disadvantages include the need for careful pH

control, possible chemical interference in treating mixed wastes, and the potential hazard of

storing and handling chlorine gas (if sodium hypochlorite is not used). If organic compounds are

present, chlorinated organics may be generated. This technology is not effective in treating

metallocyanide complexes, such as ferrocyanide. 

8.2.3.2 Ozone Oxidation

A less common cyanide treatment method is ozone oxidation. Ozone, generated

as a gas, is bubbled through a wastewater solution containing free cyanide. Part of the ozone in
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the gas phase is transferred to the solution, where it reacts with cyanide, converting it to cyanate. 

Additional ozone reacts with the cyanate to convert it to nitrogen gas, ammonia, and bicarbonate,

as shown by the reaction below.

CN- + O3 -------> CNO- + O2(8-5)

3 CNO- + 2O3 + 2OH- + 2H2O -----------> 3HCO3

- + NH3

 + N2 + 2O2(8-6)

The reaction rate is limited by mass transfer of ozone to the liquid, the cyanide

concentration, and temperature. Literature data show that amenable cyanide in electroplating

wastewaters can be reduced to below detection using the oxidation process. Ozone is not

effective in treating metallocyanide complexes, such as ferrocyanide, unless ultraviolet light is

added to the reaction tank.

One advantage ozone has over chlorine is the type of residuals formed. Chlorine

oxidation of organic compounds has the potential to form trihalomethanes. Ozone oxidizes

organic compounds to form relatively less toxic, short-chain organic acids, ketones, and

aldehydes. Equipment required for ozone oxidation of cyanides includes an ozone generator, gas

diffusion system, a mixed reaction tank, and off-gas controls to prevent the release of unreacted

ozone.

The major disadvantage of the ozone oxidation process is the capital and

operating cost. Ozone must be manufactured on site and delivered directly to the reaction tank. 

Ozone generation equipment is expensive, and facilities must also purchase closed reaction tanks

and ozone off-gas treatment equipment.

8.2.4 Chelated Metal-Bearing Wastewater

Certain MP&M wastewater contains chelating agents that form metal complexes

and interfere with conventional chemical precipitation processes. This wastewater is often

associated with electroless plating, and requires specific treatment for the chelated metals. In

general, there are three methods of treating these wastewaters:

C Reduction to elemental metal;

C Precipitation as an insoluble compound; and

C Physical separation.

8.2.4.1 Reduction to Elemental Metal

Reduction to elemental metal can be done using one of two methods. One method

is electrolytic recovery (see Section 8.1.2.6), in which the dissolved metal is deposited on a

cathode for reclamation or disposal. The electric current provides the electrons to reduce the

metal ion to its elemental form. The reaction rate and achievable concentration for this
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Figure 8-9. Chemical Reduction / Precipitation of Chelated Metals

technology depend on the volume of wastewater per unit surface area of cathode. This method

typically does not lower metal concentrations enough for wastewater discharge. 

The second method uses a reducing agent to provide the electrons to reduce the

metal. Possible reducing agents for use in chelated wastewater streams include:

C Sodium borohydride;

C Hydrazine; and

C Sodium hydrosulfite.

Upon reduction, the metal forms a particulate in solution, which can then be

removed by conventional solids removal techniques. To be used effectively these reducing

agents sometimes require the use of other chemicals for pH adjustment. Figure 8-9 presents a

flow diagram showing this method of chemical reduction of chelated metals. 

8.2.4.2 Precipitation of an Insoluble Compound

The presence of chelating agents hinders the formation of hydroxides, making

hydroxide precipitation ineffective on chelated metal-bearing wastewaters. Other precipitation

methods that are less affected by chelating agents include sulfide precipitation, dithiocarbamate

(DTC) precipitation, and carbonate precipitation. Except for DTC precipitation, all of these

technologies are discussed in Section 8.3. DTC is added to solution in stoichiometric ratio to the

metals present. DTC is effective in treating chelated wastewater; however, DTC compounds are

also a class of pesticides and, if used incorrectly, may cause process upsets in the biological

treatment used at a POTW and can potentially be harmful to the environment (e.g., lead to fish
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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kills if DTC passes through the POTW and reaches surface waters). In addition to DTC’s

potential toxic effects when misused, another disadvantage is DTC precipitation generates large

amounts of sludge.

8.2.4.3 Physical Separation

Ion exchange and reverse osmosis can separate metals from solution. These

technologies are not affected by chelating agents in the wastewater, making them effective in

treating wastewater from electroless plating. These technologies are discussed in section 8.1.2.9

and 8.1.2.10, respectively.

8.2.5 Oil-Bearing Wastewater

Some MP&M wastewater (e.g., alkaline cleaning wastewater and water-based

metal-working fluids) contains significant amounts of oil and grease. This wastewater

sometimes requires preliminary treatment to remove oil and grease and organic pollutants. 

Oil/water separation includes the breaking of oil/water emulsions as well as the gravity

separation of oil. When only free oil (i.e., non-emulsified oil) is present, only oil skimming is

necessary for effective treatment. Techniques available to remove oil include chemical emulsion

breaking followed by oil/water separation or dissolved air flotation, oil skimming, and

ultrafiltration. EPA describes these technologies in more detail below.

8.2.5.1 Chemical Emulsion Breaking

Chemical emulsion breaking is used to break stable oil/water emulsions (oil

dispersed in water, stabilized by electrical charges and emulsifying agents). A stable emulsion

will not separate or break down without chemical and or physical treatment. Chemical emulsion

breaking is applicable to wastewater containing emulsified coolants and lubricants such as

machining and grinding coolants and impact and pressure deformation lubricants. This

technology is also applicable to cleaning solutions that contain emulsified oils. Figure 8-10

shows a flow diagram of a type of continuous chemical emulsion breaking system. 
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Figure 8-10. Continuous Chemical Emulsion Breaking Unit with Coalescing Plates

Treatment of spent oil/water emulsions involves adding chemicals to break the

emulsion followed by oil/water separation. The major equipment required for chemical emulsion

breaking includes reaction chambers with agitators, chemical storage tanks, chemical feed

systems, pumps, and piping. Factors to be considered for destroying emulsions are type of

chemicals, dosage and sequence of addition, pH, mixing, heating requirements, and retention

time.

Chemicals (e.g., polymers, alum, ferric chloride, and organic emulsion breakers)

break emulsions by neutralizing repulsive charges between particles, precipitating or salting out

emulsifying agents, or weakening the interfacial film between the oil and water so it is readily

broken. Reactive cations (e.g., H+, Al+3, Fe+3) and cationic polymers are particularly effective in

breaking dilute oil/water emulsions. Once the charges have been neutralized or the interfacial

film broken, the small oil droplets and suspended solids either adsorb on the surface of the floc

that is formed, or break out and float to the top. Different types of emulsion-breaking chemicals

are used for different types of oils. If more than one chemical is required, the sequence of adding

the chemicals can affect both breaking efficiency and chemical dosages.

Another important consideration in emulsion breaking is pH, especially if cationic

inorganic chemicals, such as alum, are used as coagulants. For example, a pH of between 2 and

4 keeps the aluminum ion in its most positive state where it most effectively neutralizes charges. 

After some of the oil is broken free and skimmed, raising the pH into the 6-to-8 range with lime
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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or caustic causes the aluminum to hydrolyze and precipitate as aluminum hydroxide. This floc

entraps or adsorbs destabilized oil droplets, which can then be separated from the water. 

Cationic polymers can break emulsions over a wider pH range and thus avoid acid corrosion and

the additional sludge generated from neutralization; however, this process usually requires

adding an inorganic flocculent to supplement the adsorptive properties of the polymer emulsion

breaker.

Mixing is important in effectively breaking oil/water emulsions because it

provides proper chemical feed and dispersion. Mixing also causes droplets to collide and break

the emulsion and promotes subsequent agglomeration into larger droplets. Heating also

improves chemical emulsion breaking by lowering the viscosity and increasing the apparent

specific gravity differential between oil and water. In addition, heating increases the frequency

of droplet collisions, which helps to rupture the interfacial film. 

Once an emulsion is broken, the oil floats to the surface of the water because of

the difference in specific gravities between the oil and the water. Solids usually form a layer

between the oil and water, since some solids become suspended in the oil. The longer the

retention time, the more complete the separation between the oil, solids, and water. Oils and

solids are typically skimmed from the surface of the water in a subsequent step after chemical

emulsion breaking. Often, other techniques, such as air flotation or rotational separation (e.g.,

centrifugation), are used to enhance separation after chemical emulsion breaking. 

The advantages of chemical emulsion breaking are the high removal efficiency

potential and the possibility of reclaiming the oily waste. Disadvantages include corrosion

problems associated with acid-alum systems, operator training requirements for batch treatment,

chemical sludges produced, and poor efficiency for low oil concentrations. 

Chemical emulsion breaking is a very reliable process. The main control

parameters are pH and temperature. Maintenance is required on pumps, mixers, instrumentation

and valves, and periodic cleaning of the treatment tank is required to remove any accumulated

solids. Energy use is typically limited to mixers and pumps, but can also include heating. Solid

wastes generated by chemical emulsion breaking include surface oil and oily sludge, which are

usually contract hauled for disposal by a licensed contractor. If the recovered oil contains a low

enough percentage of water, it may be burned for its fuel value or processed and reused.

8.2.5.2 Oil Skimming

Oil skimming is a physical separation technology that removes free or floating oil

from wastewater using the difference in specific gravity between oils and water. Common

separation devices include belts, rotating drums, disks, and weir oil skimmers and coalescers. 

These devices are not suited to remove emulsified oil, which requires chemical treatment,

membrane filtration, or other treatment. Figures 8-11a and 8-11b show flow diagrams of disc

and belt oil skimming units, respectively, that can be used for small systems or on process tanks. 

The oil removal system shown in Figure 8-10 is used for large systems.
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Figure 8-11a. Disc

Oil Skimming Unit 

To separate oil from process solutions, oil skimming devices are typically

mounted onto the side of a tank and operated on a continuous basis. The disk skimmer is a

vertically rotating disk that is partially submerged in the solution (see Figure 8-11a). The disk

continuously revolves between spring-loaded wiper blades that are located above the liquid

surface. The disk’s adhesive characteristics cause the floating oil to remain on the disk. As the

disk’s surface passes under the wiper blades, the oil is scraped off and diverted to a run-off spout

for collection. Belt (see figure 8-11b) and drum skimmers operate in a similar manner, with

either a continuous belt or drum rotating partially submerged in a tank. As the surface of the belt

or drum emerges from the liquid, the oil that adheres to the surface is scraped off (drum) or

squeezed off (belt) and diverted to a collection vessel. The oil is typically contract hauled for

disposal. 

Gravity separators use overflow and underflow weirs to skim a floating oil layer

from the surface of the wastewater. A weir allows the oil layer to flow over the weir into a

trough for disposal or reuse while most of the water flows underneath the weir. A diffusion

device, such as a vertical slot weir, helps create a uniform flow through the system and increase

oil removal efficiency. 

A skimmer’s removal efficiency depends on the composition of the waste stream

and the retention time of the water in the tank. Larger, more buoyant particles require less

retention time than smaller particles. The retention time necessary for phase separation and

subsequent skimming varies from 1 to 15 minutes, depending on the wastewater characteristics. 
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Figure 8-11b. 

Belt Oil Skimming Unit 

Gravity-type separators tend to be more effective for wastewater streams with

consistently large amounts of surface oil. Drum and belt type skimmers are more applicable to

waste streams containing smaller amounts of floating oil. A gravity separator in conjunction

with a drum-type skimmer effectively removes floating contaminants from nonemulsified oily

waste streams. 

Coalescers remove oil droplets too finely dispersed for conventional gravity

separation-skimming technology. Coalescing also reduces the residence times (and therefore

separator volumes) required to separate oil from some wastes. The basic principle of coalescence

involves the attraction of oil droplets to the coalescing medium (typically plates). The oil

droplets accumulate on the medium and then rise to the surface of the solution as they combine to

form larger particles. The most important requirements for coalescing media are attraction for oil

and large surface area. Coalescing media include polypropylene, ceramic, and glass.

Coalescing stages may be integrated with a wide variety of gravity oil separators,

and some systems may incorporate several coalescing stages. A preliminary oil skimming step

avoids overloading the coalescer.
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Oil separation not only removes oil but also removes organics that are more

soluble in oil than in water. Subsequent clarification removes organic solids directly and

probably removes dissolved organics by adsorption on inorganic solids. In MP&M operations,

sources of these organics are mainly process coolants and lubricants, additives to formulations of

cleaners, paint formulations, or leaching from plastic lines and other materials. 

8.2.5.3 Flotation of Oils or Solids

Air flotation combined with chemical emulsion breaking is an effective way of

treating oily wastewater containing low concentrations of metals. Flotation is used to separate oil

and grease from the wastewater, and small amounts of metal will be removed by entrainment or

adsorption. In dissolved air flotation (DAF), air is injected into a fluid under pressure. The

amount of air that can dissolve in a fluid increases with increasing pressure. When the pressure

is released, the air comes out of solution as bubbles, which attach to oil and grease molecules and

“float” the oil and grease to the surface. Induced-air flotation uses the same separation principles

as DAF systems but the gas is self-induced by a rotor-disperser mechanism.

Figure 8-12 shows a diagram of a DAF unit. A DAF system consists of a

pressurizing pump, air injection equipment, pressurizing tank, a pressure release valve, and a

flotation tank. DAF systems operate in two modes: full-flow pressurization and recycle

pressurization. In full-flow pressurization, all influent wastewater is pressurized and injected

with air. The wastewater then enters the flotation unit where the pressure is relieved and bubbles

form, causing the oil and grease to rise to the surface with the air bubbles. In recycle

pressurization, part of the clarified effluent is recycled back to the influent of the dissolved air

flotation unit, then pressurized and supersaturated with air. The recycled effluent then flows

through a pressure release valve into the flotation unit. Pressurizing only the recycle reduces the

amount of energy required to pressurize the entire influent. DAF is the most common method of

air flotation.
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Figure 8-12. Dissolved Air Flotation Unit

8.2.5.4 Ultrafiltration

Ultrafiltration is a membrane-based process used to separate solution components

based on molecular size and shape. Using an applied pressure difference across a membrane,

solvent and small solute species pass through the membrane and are collected as permeate while

the membrane retains larger compounds, which are recovered as concentrate. Figure 8-5 shows a

typical membrane filtration unit.

Ultrafiltration typically removes materials ranging from 0.002 to 0.2 microns or

molecular-weights from 500 to 300,000. It can be used for the treatment of oily wastewater. 

Prefiltration of the ultrafiltration influent removes large particles and free oil to prevent

membrane damage and fouling. Most ultrafiltration membranes are made of homogeneous

polymer or copolymer material. The transmembrane pressure required for ultrafiltration depends

on membrane pore size, and typically ranges between 15 to 200 psi. 

Ultrafiltration typically produces a concentrated oil phase that is 2 to 5 percent of

the influent volume. Oily concentrates are typically contract hauled or incinerated, and the

permeate (water phase) can either be treated further to remove water-soluble metals and organics,

or be discharged, depending on local and state requirements. 
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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An ultrafiltration system includes: pumps and feed vessels, piping or tubing,

monitoring and control units for temperature, pressure, and flow rate; process and cleaning tanks;

and membranes. Membranes are specifically designed to handle various waste stream

parameters, including temperature, pH, and chemical compatibility. Different types of

membranes can be purchased, including hollow fiber, tubular, flat plate, and spiral wound. The

type selected depends on the type of application. For example, tubular membranes are

commonly used to separate suspended solids, whereas spiral wound membranes are used to

separate oil from water. Ultrafiltration designed for oil removal is typically more expensive than

dissolved air flotation systems. In terms of maintenance, membranes must be cleaned

periodically to ensure effective treatment.

8.3 End-of-Pipe Wastewater and Sludge Treatment Technologies

This section describes end-of-pipe technologies that MP&M facilities can use for

wastewater and sludge treatment. Section 8.3.1 discusses metal removal technologies, Section

8.3.2 discusses oil removal technologies, Section 8.3.3 discusses polishing technologies, and

Section 8.3.4 discusses sludge-handling technologies.

8.3.1 Metals Removal

The most common end-of-pipe treatment technology used in the MP&M industry

to remove dissolved metals is chemical precipitation and flocculation followed by gravity

clarification. Microfiltration can be used in place of clarification. The types of equipment used

for chemical precipitation vary widely. Small batch operations can be performed in a single tank

that typically has a conical bottom to permit removal of settled solids. Continuous processes are

usually performed in a series of tanks, including an equalization tank, a rapid-mix tank for

dispersing the precipitating chemicals, and a slow-mix tank for adding coagulants and flocculants

and for floc formation. 

For continuous-flow systems, the first tank in the treatment train is typically the

equalization tank. In the chemical precipitation system, the flow equalization tank prevents

upsets in processing operations from exceeding the hydraulic design capacity of the treatment

system, improves chemical feed control, and provides an opportunity for wastewater

neutralization.

Commingled wastewater from the equalization tank enters the rapid mix tank,

where various types of precipitation chemicals are added to convert the soluble metals into

insoluble compounds. Following precipitation, the wastewater flows into a flocculation tank

where polyelectrolytes (polymers) are added, causing the precipitated solids to coagulate into

larger particles that can be removed by gravity settling or microfiltration.

Chemical precipitation is a highly reliable technology when proper monitoring

and control are used. The effectiveness of metal precipitation processes depends on the types of

equipment used and numerous operating factors, such as the characteristics of the raw
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-34

wastewater, types of treatment reagents used, and operating pH. In some cases, operational

factors need to be optimized to achieve sufficiently low effluent concentrations. Often, subtle

changes such as varying the pH, altering chemical dosage, or extending the process reaction time

may sufficiently improve its efficiency. In other cases, modifications to the treatment system are

necessary. For example, some raw wastewater contains chemicals that may interfere with the

precipitation of metals, which may require additional treatment reagents such as ferrous sulfate,

sodium hydrosulfate, aluminum sulfate, or calcium chloride. These chemicals may be added

prior to or during the precipitation process.

Chemical precipitation systems require routine maintenance for proper operation. 

Routine maintenance includes: calibrating instrumentation and cleaning probes; maintaining

chemical pumps and mixers (inspection, cleaning, lubrication, replacing seals and packing,

replacing check valves, cleaning strainers); and monitoring tanks and sumps (inspection,

cleaning, corrosion prevention). There are several basic methods of performing chemical

precipitation and flocculation and many variations of each method. The four most common

methods are described below. Figure 8-13 shows a typical continuous chemical precipitation

system.

Hydroxide Precipitation. Hydroxide precipitation is the most common method

of removing metals from MP&M wastewater. This process is typically performed in several

stages. In an initial tank, which is mechanically agitated, alkaline treatment reagents such as lime

(calcium hydroxide or hydrated lime), sodium hydroxide, or magnesium hydroxide are added to

the wastewater to precipitate metal ions as metal hydroxides. The reaction for precipitation of a

divalent metal using lime is shown in the following equation: 

(8-7)

The precipitation process is usually operated at a pH of between 8.5 and 10.0, depending on the

types of metals in the wastewater. The pH set point is selected by choosing the value at which

metals are most effectively removed. Figure 8-14 shows the effect of pH on hydroxide

precipitation. As shown in this figure, most metal hydroxides have an optimum pH (i.e., a

minimum solubility point) at which the metal is most effectively precipitated.
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Figure 8-13. Continuous Chemical Precipitation System with Lamella Clarifier
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Figure 8-14. Effect of pH on Hydroxide and Sulfide Precipitation
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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After precipitation, the metal hydroxide particles are very fine and resistant to

settling. To increase particle size and improve the settling characteristics of the metal

hydroxides, coagulating and flocculating agents are added, usually in a second tank, and slowly

mixed. Coagulating and flocculating agents include inorganic chemicals such as alum and

ferrous sulfate, and a highly diverse range of organic polyelectrolytes with varying characteristics

suitable for different wastewaters. The particles are then settled in a separate clarification tank

(e.g., a lamella clarifier), under quiescent conditions, using the difference in density between the

solid particles and the wastewater. The solids are removed from the bottom of the settling tank

or clarifier, then transferred to a thickener or other dewatering process (see Section 8.3.4). The

effluent is either further processed in a polishing unit or discharged.

Sulfide Precipitation. The sulfide precipitation process uses equipment similar 

to that used for hydroxide precipitation. The major difference between the two processes is the

treatment reagents used. Sulfide precipitation uses either soluble sulfides (e.g., hydrogen sulfide

or sodium sulfide) or insoluble sulfides (e.g., ferrous sulfide) in place of alkali reagents used in

hydroxide precipitation. The sulfide reagents precipitate dissolved metals as metal sulfides,

which often have lower solubility limits than metal hydroxides. Therefore, the sulfide

precipitation process can (for many metals) reduce the levels of residual dissolved metal in the

treated effluent (see Figure 8-14). The sulfide precipitation reaction is shown in the following

equation:

(8-8)

Unlike hydroxides, sulfide can precipitate most chelated metals and can remove hexavalent

chromium without first reducing the chromium to its trivalent state. 

The major disadvantages of sulfide precipitation as compared to hydroxide precipitation are

higher capital and operating costs and larger sludge generation rates due to the precipitation of

ferrous ions. Additional disadvantages of sulfide precipitation are the potential for toxic

hydrogen sulfide gas generation, the potential for excessive sulfide releases in the effluent, and

the generation of sulfide odors. 

Carbonate Precipitation. Carbonate precipitation typically uses sodium

carbonate (soda ash), sodium bicarbonate, or calcium carbonate to form insoluble metal

carbonates. The reaction is shown in the following equation: 

(8-9)

Carbonate precipitation is similar in operation to hydroxide precipitation, and is

typically performed to remove metals such as cadmium or lead. For these metals, carbonate

precipitation operates at a lower pH to achieve effluent concentrations similar to those achieved

by hydroxide precipitation. Carbonate precipitation and hydroxide precipitation are sometimes

performed in conjunction, which may improve the overall performance of certain systems.
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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Carbonate precipitation is less popular than hydroxide precipitation due to the

higher cost of treatment reagents and certain operational problems, such as the release of carbon

dioxide gas, which can result in foaming and/or floating sludge. Also, since many metal

carbonates are more soluble than sulfides or hydroxides, this process is not effective for all

metals. 

Sodium Borohydride Precipitation. Sodium borohydride precipitation uses

sodium borohydride as a reducing agent to precipitate metals from solution as insoluble

elemental metals. This reaction is shown in the following equations:

(8-10)

(8-11)

This process is similar in operation to hydroxide precipitation. Borohydride

precipitation is usually performed in a pH range of 8 to 11 to efficiently utilize borohydride. The

optimum pH is determined by testing borohydride usage, reaction time, and effluent quality.

Sodium borohydride precipitation effectively removes lead, mercury, nickel,

copper, cadmium, and precious metals, such as gold, silver, and platinum, from wastewater. This

process has also been reported to reduce sludge generation by 50 percent over traditional

precipitation. However, sodium borohydride precipitation is much more expensive than other

precipitation methods.

8.3.1.1 Gravity Clarification for Solids Removal

Gravity sedimentation to remove precipitated metal hydroxides is the most

common method of clarification (solids removal) used in MP&M facilities. Typically, two types

of sedimentation devices are used: inclined-plate (e.g., lamella) clarifiers and circular clarifiers. 

Figure 8-15 shows a circular clarifier. The continuous chemical precipitation shown in Figure 8-

13 uses a lamella clarifier. Lamella clarifiers often provide superior clarification and are more

common at MP&M facilities due to the smaller area required when compared to circular

clarifiers. Lamella clarifiers typically require 65 to 80 percent of the area required for a circular

clarifier. Their design promotes laminar flow through the clarifier, even when the water

throughput is relatively high. Lamella clarifiers permit overflow rates at least two to four times

greater than conventional clarifiers. 
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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Figure 8-15. Clarifier
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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Lamella clarifiers contain inclined plates oriented at angles varying between 45

and 60 degrees from horizontal. As the water rises through the plates, the solids settle on the

lower side of the plate. The clarified effluent continues up through the plate, passes over a weir,

and is collected in an effluent holding tank. The solids collect on the lower side of the plate and

slide downward due to the inclination of the plate. The solids collect on the bottom of the

clarifier and are scraped into a sludge hopper before discharge to the thickener. 

Overflow rates for lamella clarifiers vary from 1,000 to 1,500 gpd/ft2 for metal

hydroxide sludges, assuming the flow is uniformly distributed through the plate settlers. Clarifier

inlets must be designed to distribute flow uniformly through the tank and plate settlers. In

addition, since solids can build up on plate surfaces, the clarifier should be cleaned periodically. 

Otherwise, solids may become dislodged from the plates, and degrade effluent quality, and

nonuniform buildup may adversely affect flow distribution through the plates. 

8.3.1.2 Microfiltration for Solids Removal

Microfiltration can be used as an alternative to conventional gravity clarification

after chemical precipitation. Microfiltration is a membrane-based process used to separate small

suspended particles based on size and shape. Using an applied pressure difference across a

membrane, water and small solute species pass through the membrane and are collected as

permeate while larger particles such as precipitated and flocculated metal hydroxides are retained

by the membrane and are recovered as concentrate. Microfiltration is similar to ultrafiltration

(Section 8.2.5.4) but has a larger pore size.

Microfiltration removes materials ranging from 0.1 to 1.0 microns (e.g., colloidal

particles, heavy metal particulates and their hydroxides). Most microfiltration membranes are

made of homogeneous polymer material. The transmembrane pressure required for

microfiltration typically ranges between 3 to 50 psi, depending on membrane pore size. 

Microfiltration produces a concentrated suspended solid slurry that is typically

discharged to dewatering equipment such as a sludge thickener and a filter press. The permeate

can either be treated further to adjust the pH or be discharged, depending on local and state

requirements. Figure 8-5 shows a typical membrane filtration system. 

The microfiltration system includes: pumps and feed vessels; piping or tubing;

monitoring and control units for temperature, pressure, and flow rate; process and cleaning tanks;

and membranes. Membranes are specifically designed to handle various waste stream

parameters, including temperature, pH, and chemical compatibility. Different types of

membranes can be purchased, including hollow fiber, tubular, flat plate, and spiral wound. The

configuration selected for a particular facility depends on the type of application. For example,

tubular membranes are commonly used to separate suspended solids, whereas spiral wound

membranes are used to separate oils from water. Microfiltration is more expensive than

conventional gravity clarification. Membranes must be periodically cleaned to prevent fouling

and ensure effective treatment.
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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8.3.2 Oil Removal

Operations such as machining and grinding, disassembly of oily equipment, and

cleaning can generate wastewater containing organic machining coolants, hydraulic oils, and

lubricating oils. In addition, shipbuilding facilities may commingle their oily bilge water with

other shore-side operations, resulting in a mixed oily wastewater. Data collected during MP&M

site visits, sampling episodes, and from the MP&M detailed surveys showed a variety of methods

to treat oily wastewater. The primary treatment technologies are emulsion breaking and gravity

flotation, emulsion breaking and dissolved air flotation, and ultrafiltration. EPA discussed these

technologies in the preliminary treatment section (see Section 8.2.5).

8.3.3 Polishing Technologies

Polishing systems remove small amounts of pollutants that may remain in the

effluent after treatment by technologies such as chemical precipitation and clarification and

ultrafiltration. These systems can also act as a temporary measure to prevent pollutant discharge

should the primary treatment technology fail due to a process upset or catastrophic event. The

following is a description of end-of-pipe polishing technologies that are applicable to MP&M

facilities.

8.3.3.1 Multimedia Filtration

Multimedia filtration systems are typically used to remove small amounts of

suspended solids (metal precipitates) entrained in effluent from gravity clarifiers. Multimedia

polishing filters are typically designed to remove 90 percent or greater of all filterable suspended

solids 20 microns or larger at a maximum influent concentration of 40 mg/L. Wastewater is

pumped from a holding tank through the filter. The principal design factor for the multimedia

filter is the hydraulic loading. Typical hydraulic loadings range between 4 and 5 gpm/ft2. 

Multimedia filters are cleaned by backwashing with clean water. Backwashing is timed to

prevent breakthrough of the suspended solids into the effluent. Figure 8-16 shows a diagram of a

multimedia filtration system.
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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Figure 8-16. Multimedia Filtration System

8.3.3.2 Activated Carbon Adsorption

Activated carbon adsorption removes dissolved organic compounds from

wastewater streams. For some MP&M facilities, carbon adsorption is used to polish effluent

from ultrafiltration systems treating oily wastewater. During adsorption, molecules of a

dissolved compound adhere to the surface of an adsorbent solid. Activated carbon is an excellent

adsorption medium due to its large internal surface area, generally high attraction to organic

pollutants, and hydrophobic nature (i.e., water will not occupy bonding sites and interfere with

the adsorption of pollutants). Pollutants in the wastewater bond on the activated carbon grains

until all the surface bonding sites are occupied. At that point, the carbon is considered to be

“spent.” Spent carbon requires regeneration, which results in reduced adsorption capacity

compared to fresh carbon. After several regenerations, the carbon is disposed. 

The carbon is placed in granular carbon system vessels, forming a “filter” bed.

Vessels are usually circular for pressure systems or rectangular for gravity flow systems. For

wastewater treatment, activated carbon is typically packed into one or more filter beds or

columns; a typical treatment system consists of multiple filter beds in series. Wastewater flows

through the filter beds and is allowed to come in contact with all portions of the activated carbon.

The activated carbon in the upper portion of the column is spent first (assuming flow is

downward), and progressively lower regions of the column are spent as the adsorption zone

moves down the unit. When pollutant concentrations at the bottom of the column begin to
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-43

increase above acceptable levels, the entire column is considered spent and must be regenerated

or removed.

8.3.3.3 Reverse Osmosis

Reverse osmosis is a membrane separation technology used by the MP&M

industry as an in-process step or as an end-of-pipe treatment. Section 8.2 discusses in-process

reverse osmosis. In an end-of-pipe application, reverse osmosis is typically performed to recycle

water and reduce discharge volume rather than recover chemicals. The effluent from a

conventional treatment system generally has a TDS concentration unacceptable for most rinsing

operations, and cannot be recycled. TDS concentrations can be reduced by reverse osmosis

membranes with or without some pretreatment, and the resulting effluent stream can be used for

most rinsing operations. 

8.3.3.4 Ion Exchange

Ion exchange is used for both in-process and end-of-pipe applications. Section

8.2 discusses in-process ion exchange. Ion exchange may also be used as an end-of-pipe final

polishing step, or to recycle water. This technology generally uses cation resins to remove metals

but sometimes both cation and anion columns are used. The regenerant from end-of-pipe ion

exchange is not usually amenable to metals recovery as it typically contains multiple metals at

low concentrations.

8.3.4 Sludge Handling

EPA discusses the following sludge-handling technologies in this section.

C Gravity thickening;

C Pressure filtration; 

C Sludge drying; and

C Vacuum filtration.

8.3.4.1 Gravity Thickening

Gravity thickening is a physical liquid-solid separation technology used to

dewater wastewater treatment sludge. Sludge is fed from a primary settling tank or clarifier to a

thickening tank, where gravity separates the supernatant (liquid) from the sludge, increasing the

sludge density. The supernatant is returned to the primary settling tank or the head of the

treatment system for further treatment. The thickened sludge that collects on the bottom of the

tank is pumped to additional dewatering equipment or contract hauled for disposal. Figure 8-17

shows a diagram of a gravity thickener. 

Gravity thickeners are generally used in facilities where the sludge is to be further

dewatered by a mechanical device, such as a filter press. Increasing the solids content in the
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

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Figure 8-17. Gravity Thickening

thickener substantially reduces capital and operating costs of the subsequent dewatering device

and also reduces the hauling cost. This process is potentially applicable to any MP&M site that

generates sludge. 

8.3.4.2 Pressure Filtration

The filter press is the most common type of pressure filtration used in the MP&M

industry for dewatering wastewater treatment sludges. A filter press consists of a series of

parallel plates pressed together by a hydraulic ram (older models may have a hand crank), with

cavities between the plates. Figure 8-18 shows a diagram of a plate-and-frame filter press. The

filter press plates are concave on each side to form cavities and are covered with a filter cloth. At

the start of a cycle, a hydraulic pump clamps the plates tightly together and a feed pump forces a

sludge slurry into the cavities of the plates. The liquid (filtrate) escapes through the filter cloth

and grooves molded into the plates and is forced by the pressure of the feed pump (typically

around 100 psi) to a discharge port. The solids are retained by the cloth and remain in the

cavities. This process continues until the cavities are packed with sludge solids. An air blowdown manifold is used on some units at the end of the filtration cycle to drain remaining liquid

from the system, further drying the sludge. The pressure is then released and the plates are

separated. The sludge solids or cake is loosened from the cavities and falls into a hopper or

drum. A plate filter press can produce a sludge cake with a dryness of approximately 25 to 40
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-45

Figure 8-18. Plate-and-Frame Filter Press

percent solids for metal hydroxides precipitated with sodium hydroxide, and 35 to 60 percent

solids for metal hydroxides precipitated with calcium hydroxide. The final solids content

depends on the length of the drying cycle. Filter presses are available in a very wide range of

capacities (0.6 ft3 to 20 ft3). A typical operating cycle is from 4 to 8 hours, depending on the

dewatering characteristics of the sludge. Units are usually sized based on one or two cycles per

day. 

8.3.4.3 Vacuum Filtration

Vacuum filtration is performed at some MP&M sites to reduce the water content

of sludge, increasing the solids content from approximately 5 percent to between 20 and

30 percent. These MP&M sites generally use cylindrical drum vacuum filters. The filters on

these drums are typically either made of natural or synthetic fibers or a wire-mesh fabric. The

drum is dipped into a vat of sludge and rotates slowly. A vacuum inside the drum draws sludge

to the filter. Water is drawn through the filter to a discharge port, and the dewatered sludge is

scraped from the filter. Because dewatering sludge with a vacuum filter is relatively expensive

per kilogram of water removed, the liquid sludge is frequently gravity-thickened prior to vacuum

filtration. Figure 8-19 shows a typical vacuum filter. Vacuum filters are frequently used both in
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-46

Figure 8-19. Rotary Vacuum Filter

municipal treatment plants and in a wide variety of industries. They are most commonly used in

larger facilities, which may have a thickener to double the solids content of clarifier sludge

before vacuum filtering. Often a precoat is used to inhibit filter binding. 

Maintenance of vacuum filters involves cleaning or replacing the filter media,

drainage grids, drainage piping, filter parts, and other parts. Since maintenance time may be as

high as 20 percent of total operating time, facilities may maintain one or more spare units. If this

technology is used intermittently, the facility may drain and wash the filter equipment each time

it is taken out of service. 
8.0 - Pollution Prevention Practices and Wastewater Treatment Technologies

8-47

8.3.4.4 Sludge Drying

Wastewater treatment sludges are often hauled long distances to disposal sites. 

The transportation and disposal costs depend mostly on the volume of sludge, which is directly

related to its water content. Therefore, many MP&M sites use sludge drying equipment

following dewatering or vacuum filtration to further reduce the volume of the sludge. The solids

content of the sludge dewatered on a filter press usually ranges from 25 to 60 percent. Drying

equipment can produce a waste material with a solids content of approximately 90 percent. 

There are several design variations for sludge drying equipment. A commonly

used system consists of an auger or conveyor system to move a thin layer of sludge through a

drying region and discharge it into a hopper. Various heat sources including electric, electric

infrared, steam, and gas are used for sludge drying. Some continuous units are designed such

that the sludge cake discharged from a filter press drops into the feed hopper of the unit, making

the overall dewatering process more automated. System capacities range from less than 1 ft3/hr

to more than 20 ft3/hr of feed. Sludge drying equipment requires an air exhaust system due to the

fumes generated during drying. 

8.4 References

1. U.S. Environmental Protection Agency. Facility Pollution Prevention Guide. 

EPA-600-92-088, Washington, DC. 1992.

2. U.S. Environmental Protection Agency. Development Document for Effluent

Limitations Guidelines and Standards for the Nonferrous Metals Forming and

Metal Powders Point Source Category. EPA 440-1-86-019, September, 1996.

3. Cherry, K.F. Plating Waste Treatment. Ann Arbor Sciences Publishers, Inc., Ann

Arbor, Michigan, 1982.

4. Freeman, H.M. Standard Handbook of Hazardous Waste Treatment and Disposal. 

McGraw Hill Book Company, New York, 1989.

5. Cushnie, George C., Pollution Prevention and Control Technology for Plating

Operations, National Center for Manufacturing Sciences, 1994.

6. Eckenfelder, W. Wesley. Industrial Water Pollution Control. McGrawHill, 2000.

7. Letterman, Raymond D., Water Quality and Treatment: A Handbook of

Community Water Supplies, Fifth Edition, Mc-Graw Hill, 1999.
9.0 - Technology Options

9-1

9.0 TECHNOLOGY OPTIONS

This section describes the technology options that EPA used in developing the Metal

Products and Machinery (MP&M) effluent limitations guidelines and standards. EPA developed these

options based on the technologies described in Section 8.0. Section 9.1 summarizes the methodology

EPA used to select the technologies included in the options. Section 9.2 describes the technology

options in detail. The Agency selected the technologies included in each option for

development of the MP&M effluent limitations guidelines and standards. EPA does not

require sites to implement these specific technologies to comply with the MP&M effluent

guidelines; sites can install any technology (or completely eliminate their discharge through

contract hauling or recycling as long as they achieve the final effluent limitations. EPA used

these technology options to estimate pollutant loadings and reductions (Section 12.0) and compliance

costs (Section 11.0) and to develop the MP&M effluent limitations guidelines and standards.

The MP&M technology options consist of groups of pollution prevention and

wastewater treatment technologies identified to reduce or eliminate the generation or discharge of

pollutants from MP&M sites. EPA identified these technologies from responses to the MP&M detailed

and screener surveys, MP&M site visits and sampling episodes, and technical literature (including case

studies and development documents for previously promulgated metals industry regulations).

9.1 Technology Evaluation Methods

MP&M sites generate wastewater containing oils, organic pollutants, cyanide,

hexavalent chromium, complexed metals, and dissolved metals. The MP&M industry uses many

different types of technologies to control and treat wastewater, including both in-process pollution

prevention technologies and end-of-pipe treatment and disposal technologies. To determine technology

options for each subcategory, EPA evaluated information collected from site visits, sampling episodes,

and MP&M screener and detailed surveys. EPA then grouped the most prevalent technologies

according to the type of wastewater which they treat (i.e., oily wastewater, metal-bearing wastewater,

cyanide-bearing wastewater, etc.). The Agency evaluated treatment efficiency in terms of percent

removal and final concentration (mg/L) from sampling episode data, discharge monitoring reports, and

periodic compliance reports.

EPA classified the technologies into one of the four tiers of the Environmental

Management Hierarchy (EMH) from EPA’s Facility Pollution Prevention Guide (1). This hierarchy

attempts to prioritize technologies in order of importance or benefit to the environment from source

reduction (highest priority) to disposal (lowest priority). Tables 9-1 through 9-3, presented at the end

of this section, provide data on the technologies considered for the MP&M options, grouped by their

EMH classification as follows: 

1. Table 9-1: Source reduction and pollution prevention technologies - EMH tier

1;
9.0 - Technology Options

9-2

2. Table 9-2: Recycling technologies - EMH tier 2; and

3. Table 9-3: End-of-pipe treatment and disposal technologies - EMH tiers 3 and

4.

The tables present the following for each technology: a brief technology description; the

number of sites visited by EPA using the technology; the number of survey respondents reporting using

the technology; the estimated number of sites in the MP&M industry currently using the technology; and

comments noting if EPA included the technology in the MP&M technology options (as discussed in

Section 9.2) and, where appropriate, reasons why EPA did not include the technology. Each of the

pollution prevention, recycling and treatment technologies are described in detail in Section 8.0. 

The demonstration of source reduction and some recycling technologies in the MP&M

industry was only quantifiable from the data collected in the MP&M 1996 detailed survey responses. 

However, as shown on these tables, EPA observed most of these technologies during visits to MP&M

sites. The most frequently observed and/or reported source reduction and recycling technologies were:

C Centrifugation of machining coolants;

C Centrifugation of painting water curtains;

C Conductivity probes;

C Countercurrent cascade rinsing;

C Drag-out rinsing;

C Electrolytic recovery;

C Flow restrictors;

C In-tank filtration;

C Ion exchange; and

C Regeneration of process baths.

In addition, many of the sites that EPA visited used plant maintenance and good

housekeeping practices that resulted in source reduction.

Table 9-3 presents some of the most common end-of-pipe treatment technologies in

the MP&M industry:

C Chelation breaking/precipitation to remove complexed metals;

C Chemical emulsion breaking followed by gravity separation for oil removal;

C Chemical emulsion breaking followed by dissolved air flotation (DAF) for oil

removal;

C Chemical precipitation and gravity settling for solids removal; 

C Chemical precipitation and microfiltration for solids removal;

C Chemical reduction of hexavalent chromium;

C Cyanide destruction through alkaline chlorination;
9.0 - Technology Options

9-3

C Gravity settling of wastewater (without chemical addition);

C Gravity thickening of sludge;

C Multimedia filtration (including sand filtration); 

C Neutralization (without solids removal);

C Pressure filtration of sludge; and

C Ultrafiltration for oil removal.

In addition, an estimated 31,000 of the 63,000 water-discharging MP&M sites

contract-haul some of their wastewater for off-site treatment and disposal. Many sites with treatment

technologies in place also contract-haul wastewater treatment sludges for off-site disposal.

9.2 Technology Options

EPA considered a technology to be demonstrated in the MP&M industry if the

technology effectively treated MP&M wastewater and if EPA observed the technology during at least

one MP&M site visit or at least one survey respondent reported using the technology. EPA evaluated

the performance of each technology using available analytical data from MP&M sampling episodes,

analytical data from previous effluent guidelines data collection efforts, and quantitative and qualitative

assessments from engineering site visits and literature.

EPA identified ten technology options for the MP&M industry subcategories. Table 9-

4 shows the options for each subcategory and the technologies used to establish effluent limitations and

standards. The following sections discuss the wastewater treatment technologies included in each

subcategory. Figures 9-1 through 9-6 present the technology trains for the options.

9.2.1 General Metals, Metal Finishing Job Shops, Printed Wiring Boards, Steel

Forming and Finishing, and Non-Chromium Anodizing Subcategories 

EPA evaluated four wastewater treatment technology options for the MP&M industry

subcategories whose unit operations primarily produce metal-bearing wastewater (but may also

produce some oily wastewater). Each of these options are discussed below.

Option 1

Option 1 includes segregation of wastewater streams, preliminary treatment steps as

necessary (including oil removal using oil water separation by chemical emulsion breaking), chemical

precipitation using either sodium hydroxide or lime, and sedimentation using a clarifier. Segregation of

wastewater and subsequent preliminary treatment allows for the most efficient, effective, and economic

means for removing pollutants in certain wastewater streams. These streams contain pollutants (e.g., oil

and grease, cyanide, hexavalent chromium, chelated metals, and organic solvents) that can inhibit the

performance of chemical precipitation and sedimentation treatment, while increasing the overall

treatment costs. For example, if a facility segregates its oil-bearing wastewater from its metal-bearing
9.0 - Technology Options

9-4

wastewater, then the facility can design an oil removal treatment technology based on only the oily

waste flow volume and not on the combined metal-bearing and oil-bearing wastewater flow, decreasing

the size of the overall treatment system. Treatment chemical costs are also reduced because of the

reduced volume. Preliminary treatment technologies for these types of wastewater streams are

described below. (See Section 5.0 for a more detailed description of each of these wastewater

streams).

C Oil-Bearing Wastewater. Alkaline cleaning wastewater and water-based

metal-working fluids (e.g., machining and grinding coolants) typically contain

significant amounts of oil and grease. These wastewater streams require

preliminary treatment to remove oil and grease and organic pollutants. 

Chemical emulsion breaking followed by gravity separation of oil and water

(oil/water separator or gravity flotation) effectively removes these pollutants. 

C Cyanide-Bearing Wastewater. The MP&M industry generates several

types of wastewater that may contain significant amounts of cyanide, such as

plating and cleaning wastewater. This wastewater requires preliminary

treatment to destroy the cyanide, typically performed using alkaline chlorination

with sodium hypochlorite or chlorine gas (3). 

C Hexavalent Chromium-Bearing Wastewater. The MP&M industry

generates several types of wastewater that contain hexavalent chromium,

usually generated by acid treatment, anodizing, conversion coating, and

electroplating. Because hexavalent chromium does not form an insoluble

hydroxide and is not treated by chemical precipitation and sedimentation, this

wastewater requires chemical reduction of the hexavalent chromium to trivalent

chromium. Trivalent chromium forms an insoluble hydroxide and is treated by

chemical precipitation and sedimentation. Sodium metabisulfite or gaseous

sulfur dioxide are typically used as reducing agents for hexavalent chromiumcontaining wastewater. 

C Chelated Metal-Bearing Wastewater. Electroless plating and some

cleaning operations generate water that contains significant amounts of chelated

metals. This wastewater requires chemical reduction to break the metal-chelate

bond or reduce the metal-chelate complex to an insoluble state so that it can be

removed during chemical precipitation. Sodium borohydride, dithiocarbamate,

hydrazine, and sodium hydrosulfite are used as reducing agents. 

C Organic Solvent-Bearing Wastewater. Option 1 also includes contracthauling of solvent degreasing wastewater. Based on the MP&M surveys and

site visits, most solvent degreasing operations which use organic solvents (e.g.,

1,1,1-trichloroethane, trichloroethene), are contract-hauled for off-site
9.0 - Technology Options

9-5

recycling. Some MP&M sites reported using organic solvent-water mixtures or

rinses following organic solvent degreasing. EPA found contract-hauling of this

wastewater to be the most common disposal method for these sites. 

After pretreatment of the segregated streams, chemical precipitation and gravity

clarification is used to remove total and dissolved metals. Chemical precipitation involves adjusting the

pH of the wastewater with alkaline chemicals such as lime (calcium hydroxide) or caustic (sodium

hydroxide) or acidic chemicals (such as sulfuric acid) to produce insoluble metal hydroxides. This step

is followed by a gravity settling process in a clarifier to remove the precipitated and flocculated metal

hydroxides by gravity settling (2). Segregation of wastewater streams, preliminary treatment, and final

chemical precipitation and gravity sedimentation is widely used throughout the metals industry and is

well documented as being effective in removing pollutants present in MP&M wastewater. 

Option 2

Option 2 builds on Option 1 by adding in-process pollution prevention, recycling, and

water conservation methods that allow for recovery and reuse of materials. These technologies can

reduce manufacturing costs by allowing materials to be used over a longer period before they need to

be disposed. Using these techniques or technologies along with water conservation also leads to the

generation of less pollution and results in more effective treatment of the wastewater that is generated. 

Specific Option 2 in-process pollution prevention, recycling and water conservation methods include:

C Countercurrent cascade rinsing for all flowing rinses;

C Centrifugation and recycling of painting water curtains; and

C Centrifugation and pasteurization to extend the life of water-soluble machining

coolants.

EPA observed these pollution prevention and water conservation technologies at

MP&M sites during site visits and sampling episodes. These technologies were also reported in the

MP&M surveys and documented in various literature sources (4,5).

Sites reducing their wastewater flow rates and increasing their influent pollutant

concentrations will more effectively treat the wastewater, reducing the mass of pollutants discharged in

the treated effluent. For example, a site that generates 2,600 gallons (10,000 liters) per day of raw

wastewater containing 10 mg/L of pollutants prior to treatment, implements water reduction and

recovery technologies that reduce the flow to 1,300 gallons (5,000 liters) per day and increase the

pollutant concentration to 20 mg/L prior to treatment. If the long-term average effluent concentration of

a pollutant was 0.1 mg/L, the site would discharge 1,000 mg/day of pollutant (10,000 L/day times 0.1

mg/L) prior to implementing flow reduction and recovery technologies, and 500 mg/day of pollutant

(5,000 L/day times 0.1 mg/L) after implementing the technologies. 
9.0 - Technology Options

9-6

EPA based the BPT, BCT and BAT proposed effluent limitations guidelines on Option

2 for existing direct dischargers in the General Metals, Metal Finishing Job Shops, Non-Chromium

Anodizing, Printed Wiring Board, and Steel Forming and Finishing Subcategories. EPA also based the

proposed pretreatment standards for existing sources (PSES) on Option 2 for the General Metals,

Metal Finishing Job Shops, Printed Wiring Boards, and Steel Forming and Finishing Subcategories. 

EPA did not propose PSES nor pretreatment standards for new sources (PSNS) for the NonChromium Anodizing Subcategory. EPA proposed new source performance standards (NSPS) for

new direct dischargers in the Non-Chromium Anodizing Subcategory based on Option 2.

Option 3

This option differs from Option 1 in that an ultrafilter replaces the chemical emulsion

breaking and oil/water separator for the removal of oil and grease, and a microfilter, rather than a

clarifier, follows chemical precipitation. Ultrafiltration is a separation technology that allows water and

small solute species to pass through a semi-porous membrane under pressure while emulsified oils are

retained by the membrane and recovered as concentrate (2). EPA determined through sampling

episodes that ultrafiltration systems are very effective for the removal of oil and grease at MP&M

facilities. Ultrafilters sampled by EPA achieved oil and grease removals of greater than 99 percent. 

The emulsion breaking and gravity flotation system described in Options 1 and 2 removed

approximately 96 percent of the oil and grease from the MP&M wastewater.

Microfiltration uses a pressure-driven membrane process to separate wastewater

constituents based on size and shape. Using an applied pressure difference across a membrane, solvent

and small solute species pass through the membrane and are collected as permeate. Larger

constituents such as flocculated metal hydroxide particles generated during chemical precipitation are

retained by the membrane and recovered as a concentrated solids slurry. EPA collected treatment

effectiveness data for solids removal after chemical precipitation through microfiltration. Well-operated

chemical precipitation and microfiltration systems sampled by EPA at MP&M facilities achieved an

average removal of 99.6 percent for targeted metals. Well-operated chemical precipitation and gravity

clarification systems sampled by EPA at MP&M facilities achieved an average removal of 96.7 percent

for targeted metals. 

Option 4

Option 4 includes technologies in Option 3 plus in-process flow control and pollution

prevention technologies described in Option 2, allowing for recovery and reuse of materials along with

water conservation. EPA based the NSPS and PSNS (new source) limitations and standards on

Option 4 for the General Metals, Metal Finishing Job Shops, Printed Wiring Boards, and Steel Forming

and Finishing Subcategories.
9.0 - Technology Options

9-7

9.2.2 Oily Wastes Subcategory

EPA evaluated four wastewater treatment options for the Oily Wastes Subcategory. 

EPA defines the Oily Wastes Subcategory as those facilities that only discharge wastewater from one

or more of the following unit operations: alkaline cleaning for oil removal, aqueous degreasing,

corrosion preventive coating, floor cleaning, grinding, heat treating, impact deformation, machining,

painting, pressure deformation, solvent degreasing, testing (e.g., hydrostatic, dye penetrant, ultrasonic,

magnetic flux), steam cleaning, and laundering. EPA is defining “corrosion preventive coating” as the

application of removable oily or organic solutions to protect metal surfaces against corrosive

environments. Corrosion preventive coatings include, but are not limited to: petrolatum compounds,

oils, hard dry-film compounds, solvent-cutback petroleum-based compounds, emulsions, waterdisplacing polar compounds, and fingerprint removers and neutralizers. Corrosion preventive coating

does not include electroplating or chemical conversion coating (including phosphate conversion coating)

operations. Technology options used to establish effluent limitations are discussed below.

Option 5

Effluent limitations for Option 5 are based on end-of-pipe chemical emulsion breaking

followed by gravity separation using an oil/water separator. EPA performed sampling episodes at

several facilities in the Oily Wastes Subcategory that employed chemical emulsion breaking followed by

gravity flotation and oil skimming. These systems typically achieved a 96 percent removal of oil and

grease. Breaking the oil/water emulsion requires the addition of treatment chemicals such as acid, alum,

and/or polymers to change the emulsified oils or cutting fluids from hydrophilic colloids to aggregated

hydrophobic particles. The aggregated oil particles, with a density less than water, can be removed by

gravity flotation in a coalescing plate oil/water separator. This treatment train is widely used throughout

the metals industry and is well documented as effectively removing machining coolants, emulsified

hydraulic oils, and organic pollutants present in oily MP&M wastewater. 

Option 6

Option 6 includes the technologies in Option 5 plus in-process flow control and

pollution prevention technologies, which allow for recovery and reuse of materials along with water

conservation. The specific Option 6 technologies include:

C Countercurrent cascade rinsing for all flowing rinses;

C Centrifugation and recycling of painting water curtains; and

C Centrifugation and pasteurization to extend the life of water-soluble machining

coolants.
9.0 - Technology Options

9-8

EPA based the BPT, BCT, BAT, PSES, NSPS and PSNS effluent limitations

guidelines and pretreatment standards on Option 6 for the Oily Wastes Subcategory.

Option 7

Option 7 is based on end-of-pipe ultrafiltration. Ultrafiltration is a process that allows

water and small solute species to pass through a membrane under pressure while emulsified oils are

retained by the membrane and recovered as concentrate (2). Ultrafiltration removes oil droplets

ranging from 0.002 to 0.2-microns and is expected to generate a concentrated oil phase that is 2 to 5

percent of the influent volume. Sampling episode data determined that, on average, ultrafilters will

remove greater than 99 percent of all oil and grease in the influent stream. Ultrafiltration is widely used

throughout the MP&M industry and is well documented as effectively treating machining coolants,

emulsified hydraulic oils, and organic pollutants present in oily MP&M wastewater. 

Option 8

Option 8 includes the Option 7 technology (ultrafiltration) plus the pollution prevention

and water conservation alternatives described in Option 6. Although EPA is not proposing Options 7

or 8, they were evaluated as potential options for the Oily Wastes, Shipbuilding Dry Dock, and

Railroad Line Maintenance Subcategories.

9.2.3 Shipbuilding Dry Dock and Railroad Line Maintenance Subcategories

EPA evaluated four wastewater treatment technology options for the Shipbuilding Dry

Docks and Railroad Line Maintenance Subcategories. For these subcategories, EPA considered

Options 7 and 8 in addition to the two technology options discussed below.

Option 9

Option 9 is based on end-of-pipe chemical emulsion breaking followed by DAF to

remove flocculated oils. Breaking the oil/water emulsions requires adding treatment chemicals such as

acid, alum and/or polymers to change the emulsified material from a hydrophilic colloidal dispersion to

aggregate hydrophobic particles. In the DAF tank, air bubbles created as a result of a rapid pressure

drop attach to the aggregated oil particles and pull them to the surface of the tank. A scraping

mechanism collects the oil and solids from the surface of the DAF tank. This treatment train is

demonstrated in both the shipbuilding dry dock and railroad line maintenance subcategories and is

effective for removing emulsified oils and suspended solids.

Option 10

Option 10 includes the end-of-pipe treatment technologies included in Option 9

(chemical emulsion breaking followed by DAF) plus in-process flow control and pollution prevention
9.0 - Technology Options

9-9

technologies, which allow for recovery and reuse of materials along with water conservation. The

specific Option 10 in-process technologies include:

C Countercurrent cascade rinsing for all flowing rinses;

C Centrifugation and recycling of painting water curtains; and

C Centrifugation and pasteurization to extend the life of water soluble machining

coolants.

EPA based the BPT, BCT, BAT and NSPS effluent limitations guidelines and

pretreatment standards for the Shipbuilding Dry Dock and Railroad Line Maintenance Subcategories

on Option 10. EPA did not propose pretreatment standards for new or existing sources in the

Shipbuilding Dry Dock and Railroad Line Maintenance Subcategories.

9.3 References

1. U.S. Environmental Protection Agency. Facility Pollution Prevention Guide. 

EPA/600/R-92/088, Washington, DC, 1992.

2. Freeman, H.M. Standard Handbook of Hazardous Waste Treatment and Disposal. 

McGraw Hill Publishing Company, New York, New York, 1989. 

3. Cherry, K.F. Plating Waste Treatment. Ann Arbor Sciences Publishers, Inc., Ann

Arbor, Michigan, 1982.

4. Freeman, H.M. Hazardous Waste Minimization. McGraw Hill Publishing Company,

New York, New York, 1990.

5. Cushnie, George C. Pollution Prevention and Control Technology for Plating

Operations. National Center for Manufacturing Sciences, 1994.
9.0 - Technology Options

9-10

Table 9-1

EMH Tier 1 - MP&M Source Reduction and Pollution Prevention Technologies

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesc

Estimated

Number of

MP&M Sites

Using the

Technologyc

Conductivity Probes Measure the conductivity of water in a rinse tank to

regulate the flow of fresh rinse water into the rinse system. 

A solenoid valve on the rinse system fresh water supply is

connected to the controller, which opens the valve when a

preset conductivity level is exceeded and closes the valve

when conductivity is below that level. 

38 29 320 This technology reduces the

amount of water necessary for

rinsing.

The MP&M cost model evaluates

the level of rinse flow control in

place prior to estimating costs for

countercurrent cascade rinsing. 

Countercurrent

Cascade Rinsing

Series of consecutive rinse tanks that are plumbed to

cause water to flow from one tank to another in the

direction opposite of the work flow. Water is introduced

into the last tank of the series, making it the cleanest, and

is discharged from the first tank, which has the highest

concentration of pollutants.

94 130 1569 This technology reduces the

amount of water necessary for

rinsing. This technology is

included in the technology options.

Drag-Out Rinsing Stagnant rinse, initially of fresh water, positioned

immediately after process tanks. The drag-out rinse

collects most of the drag-out from the process tank,

preventing it from entering the subsequent flowing rinses.

58 139 1737 This technology reduces the

amount of water necessary for

rinsing. The MP&M cost model

evaluates the level of rinse water

use prior to estimating costs for

countercurrent rinsing.

Flow Restrictors Prevent the flow in a pipe from exceeding a predetermined

volume. Flow restrictors can be used to limit the flow into

a rinse system. For continuously flowing rinses, a flow

restrictor controls the flow into the system, ensuring a

consistent, optimum flow rate.

45 127 1581 This technology reduces the

amount of water necessary for

rinsing. The MP&M cost model

evaluates the level of rinse flow

control in place prior to estimating

costs for countercurrent cascade

rinsing.
9-11

Table 9-1 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesc

Estimated

Number of

MP&M Sites

Using the

Technologyc

Spray Rinsing Spray water on parts above a process tank or drip/dragout tank; Uses considerably less water than immersion for

certain part configurations. This technology can also be

performed as countercurrent cascade rinsing with spray

rinses instead of overflow immersion rinses.

64 187 1767 Not applicable at all sites because

of part and process configurations;

not included in the technology

options. 

Centrifugation of

Painting Water

Curtains

Removes the heavier solids from the water curtain

allowing the water to be reused. The solids are collected

as a cake in the basket of the centrifuge. This technology 

can achieve closed-loop reuse of water curtains. 

3 1 12 Requires little maintenance, and has

been demonstrated to achieve

complete recycle with periodic

removal of sludge. This technology

is included in the technology

options. 

Filtration of Painting

Water Curtains

Removes solids by filtration (cloth, sand, diatomaceous

earth, etc.) followed by reuse. This technology can

achieve closed-loop reuse of water curtains.

2 3 20 Generates more waste than

centrifugation due to filter medium

disposal or sand filter backwash. 

This technology is not included in

the technology options. 

Settling of Painting

Water Curtains

Removes the heavier solids from the water curtains. This

technology can be used in conjunction with other removal

technologies to lessen the solids loading. 

5 5 23 Equivalent technology

(centrifugation) is included as part

of the technology options;

therefore, this technology is not

included in the technology options. 

Biocide Addition to

Lengthen Coolant Life

Can impede the growth of microorganisms that cause

rancidity. Machining coolant is often discarded as it

becomes rancid.

9 27 216 Equivalent technology

(pasteurization) is included as part

of the technology options;

therefore, this technology is not

included in the technology options. 
9-12

Table 9-1 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesc

Estimated

Number of

MP&M Sites

Using the

Technologyc

Centrifugation to

Lengthen Coolant Life

Removes the solids from the coolant to extend its usable

life. Some high-speed centrifuges can also perform liquidliquid separation to remove tramp oils and further extend

coolant life. 

18 10 78 This is a component of the coolant

recycling system included in the

technology options. 

Filtration to Lengthen

Coolant Life

Removes the solids from the coolant using filters such as

cloth, sand, carbon, etc. 

18 18 142 Equivalent technology is included

as part of the technology options;

therefore, this technology is not

included in the technology options.

Skimming of Tramp

Oils to Lengthen

Coolant Life

Extends the coolant life. Tramp oil buildup often makes

machining coolant unusable.

8 9 82 Equivalent technology (liquid-liquid

centrifugation) is included as part of

the technology options; therefore,

this technology is not included in

the technology options.

Pasteurization to

Lengthen Coolant Life

Kills the microorganisms that cause rancidity. Machining

coolant is often discarded as it becomes rancid. 

1 2 18 This is a component of the coolant

recycling system included in the

technology options. 

EMH - Environmental Management Hierarchy.

NA - Numerical data are not available.

Source: MP&M site visits, MP&M sampling episodes, MP&M surveys and technical literature.

a

Indicates the number of MP&M sites visited by EPA using the listed technology. EPA visited a total of 162 sites.

bNumber of survey sites based on data collected in 1996 only. The 1989 survey did not request this information. 

c

Indicates the estimated number of MP&M sites currently performing this technology based on the 1996 Detailed Survey Results. EPA estimates that the MP&M industry

includes 63,000 wastewater discharging sites. EPA estimated numbers in this column using statistical weighting factors for the 1996 MP&M Detailed survey respondents.
9.0 - Technology Options

9-13

Table 9-2

EMH Tier 2 - MP&M Recycling Technologies

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Evaporation with

Condensate

Recovery

Leaves a concentrated residue for disposal and condenses

the water vapor for reuse.

4 15 147 Energy-intensive. This technology

is not included in the technology

options. 

Ion Exchange Combined cation and anion exchange used to remove metal

salts from electroplating rinsewater. Effluent from the ion

exchange is returned to the electroplating rinse system. Ion

exchange regenerants are either discharged to the end-ofpipe chemical precipitation unit for metals removal, or

metals are recovered by electrowining.

29 33 437 Permeate contains moderate

dissolved solids concentrations and

may be reused in noncritical unit

operations. This technology is not

included in the technology options. 

While the technology may be

effective for individual sites EPA

cost estimates show that ion

exchange is not cost effective for

the industry as a whole.

Reverse Osmosis Forces wastewater through a membrane at high pressure,

leaving a concentrated stream of pollutants for disposal. 

Reverse osmosis may provide an effluent clean enough for

reuse.

2 1 3 Similar in application to end-of-pipe

ion exchange, but not as well

demonstrated. This technology is

not included in the technology

options.
9-14

Table 9-2 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Electrolytic Recovery

(Electrowinning)

Recovers dissolved metals from concentrated sources. For

rinses, electrolytic recovery is typically restricted to dragout rinses. Flowing rinses are generally too dilute for

efficient electrolytic recovery. This technology is effective

on the concentrated regenerant from ion exchange.

19 23 142 Works in conjunction with drag-out

rinsing and in-process ion exchange

to recover metals from wastewater. 

This technology is not included in

the technology options. 

EMH - Environmental Management Hierarchy.

NA - Numerical data are not available.

Source: MP&M site visits, MP&M sampling episodes, MP&M surveys and technical literature.

a

Indicates the number of MP&M sites visited by EPA using the listed technology. EPA visited a total of 162 sites.

bNumber of survey sites based on data collected in 1996 only. The 1989 survey did not request this information. 

c

Indicates the estimated number of MP&M sites currently performing this technology based on the 1996 Detailed Survey Results. EPA estimates that the MP&M industry

includes 63,000 wastewater discharging sites. EPA estimated numbers in this column using statistical weighting factors for the 1996 MP&M Detailed survey respondents.
9.0 - Technology Options

9-15

Table 9-3

EMH Tiers 3 and 4 - MP&M End-of-Pipe Treatment and Disposal Technologies

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Chemical Emulsion

Breaking Followed by

Gravity Oil/Water

Separation

Adds acids (typically sulfuric), polymer, and sometimes alum to

oil-bearing wastewater to break oil/water emulsions for

subsequent gravity separation.

11 56 958 This technology is included in the

technology options.

Chemical Reduction of

Hexavalent Chromium

Reduces hexavalent chromium to trivalent chromium using a

reducing agent such as sulfur dioxide, sodium bisulfite, or sodium

metabisulfite.

74 103 1,839 This technology is included in the

technology options.

Cyanide Destruction

Through Alkaline

Chlorination

Destroys cyanide by adding chlorine (usually sodium

hypochlorite or chlorine gas) to first oxidize cyanide to cyanate,

then cyanate to carbon dioxide and nitrogen gas.

52 53 1,136 This technology is included in the

technology options.

Chemical Emulsion

Breaking Followed by

DAF

Adds acids (typically sulfuric), polymer, and sometimes alum to

oil-bearing wastewater to break oil/water emulsions for

subsequent gravity separation. Removes oils and solids by

bubbling gas through the wastewater, bringing solids to the

surface for subsequent removal.

12 25 244 This technology is included and has

been costed in the technology options

for shipbuilding dry docks and railroad

line maintenance subcategories. 

Oil Skimming of Oily

Wastewater Streams

Removes free floating oil by gravity separation and mechanical

skimming. This technology does not remove emulsified oils.

38 89 2,087 Not as effective as chemical emulsion

breaking followed by gravity flotation

using an oil/water separator or DAF. 

This technology is not included in the

technology options.

Cyanide Oxidation by

Ozone

Ozone oxidizes cyanide to ammonia, carbon dioxide and oxygen. 0 1 4 The generation of ozone requires

expensive equipment and safety

controls. An equivalent technology

(cyanide destruction through alkaline

chlorination) is included in the

technology options. Therefore, this

technology is not included in the

technology options. 
9-16

Table 9-3 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Chelation Breaking/

Precipitation to Remove

Complexed Metals

Wastewater from electroless plating and some cleaning

operations contains chelated metals which cannot be removed by

chemical precipitation. Strong reducing agents such as

dithiocarbamate are added to break the metal-organic chelate

bond and precipitate the metal.

11 49 555 Used to treat electroless plating

wastewater prior to chemical

precipitation. This technology is

included and costed in the technology

options.

Ultrafiltration Generally used to remove emulsified or free-floating oils. This

technology also removes other solids. Uses a membrane of very

small pore size.

17 23 351 This technology is included in the

technology options for new sources.

Activated Carbon

Adsorption

Removes dissolved organic pollutants by filtration through

activated carbon. The dissolved organics are removed by the

process of adsorption. This technology requires preliminary

treatment to remove suspended solids and oil and grease. 

8 21 165 Applicable to wastewater containing

dilute concentrations of nonpolar

organic pollutants. MP&M treatment

influent streams typically do not

contain dilute concentrations of

nonpolar organic pollutants. This

technology is not included in the

technology options. 

Aerobic Biological

Treatment

Biochemically decomposes organic materials in the presence of

oxygen. The decomposition is performed by microorganisms.

1 4 130 Applicable to wastewater with high

concentrations of organic pollutants.

MP&M treatment influent streams

typically do not contain high

concentrations of organic pollutants. 

EPA visited one site that operated this

technology to treat nonprocess

wastewater. This technology is not

included in the technology options. 

Air Stripping Removes dissolved volatile organic pollutants by contacting the

organics in the wastewater with a continuous stream of air

bubbles. Volatile organic pollutants are transferred from the

wastewater to the air.

0 2 14 Applicable to wastewater containing

high concentrations of volatile organic

pollutants. MP&M treatment influent

streams typically do not contain high

concentrations of volatile organic

pollutants. This technology is not

included in the technology options. 
9-17

Table 9-3 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Neutralization Acidic or alkaline chemicals used to neutralize high or low pH

wastewater to within an acceptable range. Common acids

include sulfuric and hydrochloric. Common alkaline chemicals

include lime (calcium hydroxide) and sodium hydroxide.

51 233 3,713 Adjusts pH, but does not remove

suspended solids and dissolved metals. 

This technology is not included in the

technology options. 

Chemical Precipitation

and Gravity 

Sedimentation

Removes metals by precipitating insoluble compounds such as

hydroxides, sulfides, or carbonates. Precipitation as metal

hydroxides using lime (calcium hydroxide) or sodium hydroxide

is the most common. Precipitated and flocculated solids are

removed by gravity sedimentation in a clarifier.

117 203 2,981 This technology is included and costed

in the technology options. 

Chemical Precipitation

and Membrane Filtration

Removes metals by precipitating insoluble compounds such as

hydroxides, sulfides, or carbonates. Precipitation as metal

hydroxides using lime (calcium hydroxide) or sodium hydroxide

is the most common. Precipitated and flocculated solids are

removed by microfiltration through a porous membrane.

5 5 36 This technology is included and costed

in the new source technology options.

Atmospheric

Evaporation

Includes both natural solar evaporation and forced atmospheric

evaporation by which the evaporation rate is accelerated by

increased temperature, air flow, and surface area.

3 12 142 Usually occurs in ponds or lagoons

with large space requirements. Also,

atmospheric evaporators have

significant energy requirements as well

as possible cross-media impacts. This

technology is not included in the

technology options. 

Ion Exchange Polishing technique after metals precipitation to scavenge low

concentrations of residual metals (cations). Anions remain in

solution and are discharged. Concentrated metal containing

regenerants are typically returned to the metals precipitation

system.

13 39 251 Usually used in conjunction with

another end-of-pipe technology (e.g.,

following chemical precipitation). 

Based on analytical data collected

during the MP&M sampling program,

this technology does not provide

significant metal removals beyond

chemical precipitation and

sedimentation. This technology is not

included in the technology options. 
9-18

Table 9-3 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Multimedia Filtration Uses filter media of different grain size to remove solids from

wastewater. Larger particles are removed by the coarser media

and the smaller particles are removed by the finer media. Media

include garnet, sand, and anthracite coal. The filter is

periodically backwashed to remove solids.

11 16 354 Usually used in conjunction with

another end-of-pipe technology (e.g.,

following chemical precipitation). 

Based on analytical data collected

during the MP&M sampling program,

this technology does not provide

significant additional metal removals

beyond chemical precipitation and

sedimentation. EPA evaluated this

technology in the BCT technology

options. 

Sand Filtration Uses a sand filter to remove solids from wastewater. The filter

is periodically backwashed to remove solids.

37 41 830 Usually used in conjunction with

another end-of-pipe technology (e.g.,

following chemical precipitation). 

Based on analytical data collected

during the MP&M sampling program,

this technology does not provide

significant metal removals beyond

chemical precipitation and

sedimentation. This technology was

not included in the technology options. 

Gravity Settling Physically removes suspended particles by gravity. This

process does not include the addition of any chemicals.

7 46 1,679 Only settles suspended solids and does

not remove dissolved metals. This

technology is not included in the

technology options. 

Centrifugation of Sludge Uses centrifugal force to separate water from solids. 

Centrifugation dewaters sludges, reducing the volume and

creating a semisolid cake. Centrifugation of sludge can typically

achieve a sludge of 20-35% solids.

4 9 127 Energy intensive, and is therefore not

included in the technology options. 

Equivalent sludge dewatering

technologies (gravity thickening and

pressure filtration) are included and

costed in the technology options.
9-19

Table 9-3 (Continued)

9.0 - Technology Options

Technology Technology Description

Demonstration Status

Comments

Number

of Sites

Visiteda

Number

of

Survey

Sitesb

Estimated

Number of

MP&M Sites

Using the

Technologyc

Gravity Thickening of

Sludge

Physically separates solids and water by gravity. Water

separates from the sludge and is decanted from the top of the

mixture. Gravity thickening can typically thicken sludge to 5%

solids.

60 85 1,161 This technology is included and costed 

in the technology options. 

Pressure Filtration of

Sludge

Physically separates solids and water by pressure filtration. 

Most commonly performed in a plate-and-frame filter press

where the sludge builds up between the filter plates and water is

filtered through a cloth. Pressure filtration can produce a sludge

cake with greater than 40% solids.

113 189 3,106 This technology is included in the

technology options.

Sludge Drying Dries sludge by heating, which causes the water in the sludge to

evaporate. 

22 48 835 This technology is energy intensive, and

is therefore not included in the

technology options. Equivalent

technologies (gravity thickening and

pressure filtration) are included in the

technology options.

Vacuum Filtration of

Sludge

The MP&M cost model evaluates the level of rinse flow control

in place prior to estimating costs for countercurrent cascade

rinsing.

8 9 193 Energy intensive and typically does not

achieve as high a percent solids as

pressure filtration. This technology is

not included in the technology options. 

Equivalent sludge dewatering

technologies (gravity thickening and

pressure filtration) are included in the

technology options.

EMH - Environmental Management Hierarchy.

NA - Numerical data are not available.

Source: MP&M site visits, MP&M sampling episodes, MP&M surveys and technical literature.

a

Indicates the number of MP&M sites visited by EPA using the listed technology. EPA visited a total of 162 sites.

b

Indicates the number of model sites that reported using this technology. Based on 691 MP&M survey respondents.

c

Indicates the estimated number of MP&M sites currently performing this technology. EPA estimates that the MP&M industry includes 63,000 wastewater discharging sites. 

EPA estimated numbers in this column using statistical weighting factors for the MP&M survey respondents.
9-20

9.0 - Technology Options

Table 9-4

Technology Options by Subcategory

Treatment or Source Reduction

Technology

General Metals, Metal Finishing Job Shops,

Printed Wiring Boards, Steel Forming and

Finishing, and Non-Chromium Anodizing

Subcategories Oily Waste Subcategory

Shipbuilding Dry

Dock and Railroad

Line Maintenance

Subcategories

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6

Option

7

a

Option

8

a Option 9 Option 10

Chemical Precipitation T T T T

Gravity Clarification for Metal Hydroxide

Removal

T T

Microfiltration for Metal Hydroxide Removal T T

Emulsion Breaking and Gravity Separation for

Oil Removal

T T T T

Ultrafiltration for Oil Removal T T T T

Emulsion Breaking and DAF for Oil Removal T T

Alkaline Chlorination for Cyanide Removal T T T T

Hexavalent Chromium Reduction T T T T

Reduction/Precipitation of Chelated Metals T T T T

Contract Hauling of Organic Solvent-Bearing

Wastewater

T T T T T T T T T T

Countercurrent Cascade Rinsing T T T T T

Centrifugation and Recycling of Painting

Water Curtains

T T T T T

Centrifugation and Pasteurization to Extend

Life of Water Soluble Machining Coolants

T T T T T

 DAF: Dissolved air flotation

aEPA evaluated this option for Shipbuilding Dry Dock and Railroad Line Maintenance Subcategories along with Options 9 and 10.
9-21

9.0 - Technology Options

Figure 9-1. End-of-Pipe Treatment Train for Options 1 and 2 Considered for the Following Subcategories:

General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Boards, and Steel Forming and Finishing
9-22

9.0 - Technology Options

Figure 9-2. In-Process Water Use Reduction Technologies for Options 2 and 4 Considered for the Following Subcategories:

General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Boards,

and Steel Forming and Finishing
9-23

9.0 - Technology Options

Figure 9-3. End-of-Pipe Treatment Train for Options 3 and 4 Considered for the Following Subcategories:

General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Boards, and Steel Forming and Finishing
9-24

9.0 - Technology Options

Figure 9-4. End-of-Pipe Treatment Train for Options 5 and 6 

Considered for the Oily Wastes Subcategory
9-25

9.0 - Technology Options

Oil to Reclaim

Ultrafiltration

Wastewater

Discharge

Oily

Wastewater

Figure 9-5. End-of-Pipe Treatment Train for Option 7 and 8 

Considered for the Following Subcategories: Oily Wastes, 

Railroad Line Maintenance, Shipbuilding Dry Dock
9-26

9.0 - Technology Options

Oily

Wastewater

Acid Polymer

Chemical

Emulsion

Breaking

Oil to Reclaim

Dissolved

Air

Flotation

Wastewater

Discharge

Figure 9-6. End-of-Pipe Treatment Train for Options 9 and 10 Considered for the 

Railroad Line Maintenance and Shipbuilding Dry Dock Subcategories
10-1

10.0 LONG-TERM AVERAGES AND VARIABILITY FACTORS

This section summarizes the technology effectiveness evaluation and the longterm average (LTA) concentrations and variability factors calculated for the selected end-of-pipe

MP&M wastewater treatment technologies. These technologies are:

C Chemical precipitation and clarification (using sedimentation or

membrane filtration) with preliminary treatment, where applicable, for

treatment of regulated metals and suspended solids. Preliminary treatment

may include chromium reduction, batch chemical precipitation for

concentrated waste streams, and chemical reduction/precipitation of

chelated metals.

 

C Ultrafiltration for treatment of oil and grease and organic pollutants.

 

C Dissolved air flotation (DAF) for treatment of oil and grease and organic

pollutants.

 

C Chemical emulsion breaking and oil-water separation for treatment of oil

and grease and organic pollutants.

 

C Cyanide destruction with alkaline chlorination for treatment of cyanide.

Section 8.3 describes these technologies in detail, as well as the physical and

chemical principles underlying their operation. Section 3.3 describes EPA’s data-gathering

activities at MP&M sites that use each of these technologies.

This section describes the data sources used in the technology effectiveness

evaluation (Section 10.1); the data-editing procedures used in assessing the technologies (Section

10.2); and the LTA concentrations, variability factors, and limitations calculated from this

assessment (Sections 10.3 and 10.4).

EPA used the following methodology to estimate the daily maximum and monthly

average limitations for the regulated pollutants:

1. Identify the sampling episodes that match the technology option (Section

10.1).

2. Evaluate the data from each episode to identify data that demonstrate

effective treatment (Section 10.2).

 

3. Calculate the LTA for each sampling episode data set from the daily

effluent concentrations for each pollutant passing the technology

effectiveness evaluation. The episode-level LTA for each pollutant is the

arithmetic average of the daily concentration at each sampling episode. 

For samples where a pollutant was not detected, EPA used the sample

detection limit to calculate the LTA. The Agency defined the LTA for

each pollutant as the median of the episode-level LTAs (Section 10.3.4).
10.0 - Long-Term Averages and Variability Factors

10-2

 

4. Use the modified delta-lognormal model to estimate episode-level daily

and episode-level 4-day average variability factors (Section 10.3.1) for

those episode data sets that had at least four samples of a pollutant passing

the technology effectiveness evaluation, including at least two detected

values. 

 

5. Determine the daily variability factor and the 4-day average variability

factor. EPA defines the daily variability factor for a pollutant as the

average of the episode-level daily variability factors and defines the 4-day

average variability factor as the average of the episode-level 4-day average

variability factors (Section 10.3.5).

 

6. Calculate the daily and monthly average limitations by multiplying the

constituent LTA by the daily and 4-day constituent variability factors,

respectively (Section 10.3.7).

10.1 Sources of Technology Performance Data

EPA, industry, and local sanitation districts collected data from wastewater

treatment systems during separate sampling episode programs conducted at MP&M facilities. 

Sampling episode reports maintained in the administrative record for this rulemaking present the

data collected during each sampling episode. All sampling episodes were conducted using the

EPA sampling and chemical analysis protocols as described in Section 3.3. The following

subsections describe sampling programs conducted by EPA and other entities as well as industrysupplied monitoring data.

To determine the limits for each subcategory for each technology option, EPA

subdivided the data by subcategory and technology option. Section 7.0 discusses regulated

pollutants for MP&M subcategories. Table 10-1 lists the number of evaluated treatment systems

per subcategory.

10.1.1 EPA Sampling Program

EPA conducted 57 sampling episodes at MP&M sites ranging from one to five

days as discussed in Section 3.3. To assess possible influent and effluent variability caused by

variations in site operations, EPA conducted multiple sampling episodes at three of these sites. 

Data from these sampling episodes are stored in the LTA Database. Table 10-2 summarizes the

number of sampling episodes and data points in the LTA Database from EPA-conducted

sampling episodes.

For some sampling points on some days, EPA collected duplicate samples for

quality assurance checks, or multiple sample fractions to develop manual composite samples. 

EPA averaged the concentrations as described below for evaluating treatment performance and

calculating long-term averages and variability factors.
10.0 - Long-Term Averages and Variability Factors

10-3

 

C Duplicate samples. As discussed in Section 4.0, EPA collected duplicate

samples at many sampling points as a quality control measure. EPA

averaged the concentrations for the original and duplicate samples for each

parameter. For samples where a pollutant was not detected in a sample,

EPA used the sample detection limit to calculate the average.

 

C Multiple composite fractions. EPA collected multiple grab composite

samples for oil and grease and total petroleum hydrocarbons. For these

samples, EPA averaged the composite results over the sample day. When

a pollutant was not detected in a sample, EPA used the sample detection

limit to calculate the average.

10.1.2 Sampling Episodes Conducted by Industry and Local Sanitation Districts

Local sanitation districts and the industry conducted sampling episodes ranging

from three to five days as discussed in Section 3.3. To assess possible influent and effluent

variability caused by variations in site operations, sanitation districts conducted multiple

sampling episodes at two sites, one of which EPA also sampled. Data from these sampling

episodes are stored in the LTA Database. Table 10-3 summarizes the number of sampling

episodes and data points in the LTA Database associated with samples collected by industry and

local sanitation districts.

10.1.3 Industry-Supplied Effluent Monitoring Data

To augment data collected during sampling episodes, EPA requested effluent

monitoring data from sampled sites to further evaluate and refine variability factors. EPA

attempted to obtain effluent monitoring data that represented each regulated subcategory and

each technology option and used industry effluent data that met the following criteria: 

 

C Data were from a treatment system passing all criteria in the technologyeffectiveness evaluation (see Section 10.2).

 

C The site collected effluent monitoring data from a location comparable to

the one used by EPA during the sampling episode (e.g., the site did not

typically commingle the effluent with other waste streams, such as storm

water or sanitary waste, before the sampling point). As an exception, EPA

used a site's data even when the monitoring location followed pH

adjustment, since this treatment step would not change the concentrations

of regulated pollutants. 

 

C Wastewater treatment processes were comparable to those at the time of

the sampling episode (i.e., no changes were made to the system that could

change treatment effectiveness). If the wastewater treatment process had
10.0 - Long-Term Averages and Variability Factors

10-4

been modified, EPA requested data for a period when the treatment 

processes were similar to those at the time of the sampling episode.

 

C Wastewater treatment influent characteristics were comparable to those at

the time of the sampling episode (i.e., the site made no major

manufacturing process changes that would change the influent

characteristics). If changes had occurred subsequent to the sampling

episode, EPA requested data for a period when processes were similar to

those during the sampling episode.

EPA collected data during site visits and sampling episodes, from voluntary

submissions by sites, or by written request. The database contained additional effluent data from

14 sites. Table 10-4 summarizes supplementary effluent monitoring data obtained from sites. 

Because these data are not in a form that allows direct use for calculating limits or for

comparison to the proposed limits, EPA was not able to use these data in setting or evaluating the

compliance aspects of the proposed limits and standards. However, following proposal, EPA

will reformat and evaluate these long-term effluent monitoring data in relation to the proposed

limits.

10.2 Evaluation of Treatment Effectiveness

EPA reviewed MP&M sampling data to identify data from well-designed and

well-operated treatment systems to calculate the LTA concentrations and variability factors. 

During the review, EPA focused on data for pollutants processed and treated by the MP&M

industry. Figure 10-1 summarizes the technology effectiveness data-editing procedures discussed

in this section. As shown on this figure, the data editing process consisted of four major steps:

 

1. Identification of pollutants not present in the raw wastewater at sufficient

concentrations to evaluate treatment effectiveness;

 

2. Assessment of general performance of the treatment system;

 

3. Identification of process upsets that could affect treatment effectiveness

and sampling techniques that could affect data quality; and

 

4. Identification of wastewater treatment chemicals. 

 

EPA did not calculate LTAs for pollutants that were not MP&M pollutants of

concern (see Section 7.0). The LTA database contains 59,211 influent and effluent data points

for MP&M pollutants of concern associated with the MP&M end-of-pipe technology options. Of

these data points, 29,639 were influent data points. A data point is a concentration of a specific

constituent from a given sampling day at a sampled point.
10.0 - Long-Term Averages and Variability Factors

10-5

LTA DATABASE

Contains treatment influent and effluent analytical

data from 58 sites collected during 63 sampling episodes,

including flags identified in preceding steps.

Identification of pollutants in the wastewater at sufficient

concentrations to evaluate removal:

(1) Pollutant not detected in any (Flag=N) raw influent 

 samples to a treatment system.

(2) Pollutant not detected at an average concentration

 greater than 10 times the minimum level of detection 

 (Flag=C) in the raw influent wastewater samples to a 

 treatment system.

(3) Pollutant not detected in most (Flag=F) raw influent

 samples to a treatment system.

(4) Pollutants detected at low concentrations on all

 sampling days (Flag=LC) or all targeted pollutants

 detected at low concentration (Flag=LA) in the

 raw influent to a treatment system.

(5) Metal type not processed on site (Flag=1).

(6) Metal type not present in raw wastewater because

 of potential dilution from poor water-use practices

 (Flag=2).

Assessment of treatment system performance:

(1) Treatment unit initially included in analysis, but upon

 further research, technology was not an MP&M

 technology option (Flag=O).

(2) Treatment system not operated at proper pH for

 optimal removal of targeted metals (Flag=P).

(3) Poor removal of most targeted pollutants processed on

 site, poor removal of solids, and/or effluent 

 concentrations that did not reflect BPT/BAT level of 

 performance (Flag=A). 

Identification of process upsets on site during sampling 

(Flag=V).

Identification of wastewater treatment chemicals (Flag=G).

Figure 10-1. Summary of Technology Performance Data-Editing Procedures
10.0 - Long-Term Averages and Variability Factors

10-6

EPA flagged each data point failing an evaluation criterion and only included

unflagged effluent data points in the LTA and variability factor calculations. One pollutant at a

sampling point could have multiple flags, depending on the number of evaluation criteria it did

not meet. Where EPA conducted multiple episodes at one site, the Agency evaluated each

episode separately; therefore, EPA may have flagged a pollutant for a different reason for each

episode. Sections 10.2.1 through 10.2.4 describe the flags used in editing the database. Table

10-5 lists the number of effluent data points flagged for each technology option. The number of

flagged data points listed in this table reported only the initial flag for a pollutant. For example,

as shown in Table 10-5, EPA flagged 2,061 data points with a “N” flag. Of the remaining

unflagged points, the Agency flagged 453 with a “C” flag, then of the remaining unflagged data,

it flagged 10 with an F (see Figure 10-1 for a description of each flag).

Table 10-6A presents data from sampled facilities from all applicable

subcategories for total and amenable cyanide. Tables 10-6B through 10-6J present, for each

pollutant proposed for regulation and each subcategory, the daily effluent concentration for all

other data points that passed the data editing criteria. The Steel Forming and Finishing

Subcategory’s mass-based limits are based on the General Metals Subcategory concentration

limits; therefore, data for both subcategories are presented together on Table 10-6B through

10-6J. Tables 10-6B only list data from sampled facilities within each subcategory. In

developing the proposed effluent limitations and standards, EPA, in certain cases, transferred

LTAs and variability factors from other subcategories (see Tables 10-8B through 10-8K).

10.2.1 Identification of Pollutants Not Present in the Raw Wastewater at Sufficient

Concentrations to Evaluate Treatment Effectiveness

EPA evaluated the concentrations of pollutants of concern in the influent to each

treatment system to determine which pollutants were present at concentrations high enough to

assess the treatment effectiveness of the system. EPA flagged the influent and corresponding

effluent data points for all specific pollutants in a treatment system that met the following

criteria: 

1. EPA assigned a flag of “N” to a pollutant if EPA did not detect the

pollutant in any of the raw influent wastewater samples to a treatment

system during a sampling episode. 

2. EPA assigned a flag of “C” to a pollutant if EPA did not detect the

pollutant in the raw influent wastewater to a treatment system at an

average concentration of greater than 10 times the minimum level of

detection during the sampling episode. The minimum level is the lowest

concentration that can be reliably measured by an analytical method. EPA

calculated the average influent concentration using the sample detection

limit when the pollutant was not detected in the influent. 
10.0 - Long-Term Averages and Variability Factors

10-7

3. EPA assigned a flag of “F” to a pollutant if EPA detected the pollutant in

the raw influent to a treatment system at an average concentration greater

than 10 times the minimum level (see Step 2), but the Agency did not

detect the pollutant on most sampling days, and, when detected, EPA

detected it at a low concentration. EPA assigned this flag on a case-bycase basis for each pollutant. 

4. EPA assigned a flag of “LC” to a pollutant if EPA detected the pollutant in

the influent to a treatment system at an average concentration greater than

10 times the minimum level (see Step 2) but EPA did not detect the

pollutant on all sampling days at concentrations high enough to assess

treatment effectiveness. EPA assigned this flag on a case-by-case basis for

each pollutant.

5. EPA assigned a flag of “LA” on a case-by-case basis to all pollutants

associated with a treatment system if the concentrations of all the targeted

pollutants detected in the raw influent were not detected at high enough

concentrations to assess treatment effectiveness. EPA assigned this flag to

all effluent points associated with three episode-specific treatment units:

one ultrafiltration unit, one DAF unit, and one chemical precipitation with

microfiltration for clarification. 

6. If a sampled site did not process a raw material associated with a pollutant

(e.g., cadmium or cyanide) then EPA assigned all unflagged data points for

that pollutant a flag of “1.” EPA assigned this flag to specific pollutants at

effluent points associated with 14 chemical precipitation systems.

7. Because the proposed MP&M effluent limitations guidelines and standards

include water conservation practices and pollution prevention

technologies, EPA reviewed information obtained from sampled sites to

identify unit operations for which sites did not have water conservation

and pollution prevention technologies in place. EPA assigned a flag of “2”

to pollutants affected by poor water-use practices. If the poor water-use

practices only affected a specific pollutant (for example, a cadmium

electroplating line that did not have water conservation practices in place),

EPA assigned this flag only to the affected pollutant. 

EPA assigned this flag to specific metals in the effluent data for seven

chemical precipitation systems and cyanide effluent data for one cyanide

destruction system. EPA also assigned this flag to all effluent data points

for a chemical precipitation system sampled during two episodes because

sampling personnel discovered that overflow rinses from metal finishing

operations flowed to the treatment system when the site discontinued

production, thus diluting the influent stream to the treatment system.
10.0 - Long-Term Averages and Variability Factors

10-8

10.2.2 Assessment of General Treatment System Performance

EPA assessed the performance of each sampled treatment system to identify welldesigned and well-operated systems. For this assessment, EPA first identified MP&M unit

operations performed on site to determine which pollutants (e.g., metals, cyanide, and oil and

grease) the site generated. EPA focused on these pollutants to assess treatment systems because

sites design systems to treat the specific pollutants generated on site. In some cases, complete

data on the types of pollutants generated at a site were unavailable because EPA toured only a

portion of the site. In these cases, EPA reviewed the concentrations of pollutants in the raw

wastewater to identify pollutants generated on site. EPA then performed the following technical

analyses of the treatment systems to determine which data would be included in the LTA

concentrations and variability factors.

1. EPA identified treatment systems that included technologies that were not

a part of EPA's technology options. 

C EPA identified one chemical precipitation and sedimentation

system that included biological treatment and assigned an “O” flag

to all the effluent data associated with this treatment system.

C EPA identified a cyanide destruction system that added chlorine

gas for treatment and assigned an “O” flag to cyanide data for the

effluent associated with this treatment system. 

2. EPA identified chemical precipitation and cyanide destruction systems that

the site did not operate at the optimum pH for treatment of the targeted

pollutants. The optimum pH for removal of metals by a chemical

precipitation system varies with the combination of metals processed at a

site; therefore, EPA based its evaluation of each chemical precipitation

system on the site-specific metals processed or treated. 

C EPA assigned a flag of “P” to all effluent data associated with four

chemical precipitation and sedimentation systems identified as

operating outside pH ranges considered to be optimum for removal

of the site-specific targeted metals.

C EPA assigned flag of “P” to all amenable and total cyanide effluent

data associated with two cyanide destruction systems identified as

operating outside the optimum pH range for cyanide oxidation.

3. EPA identified treatment systems where the targeted pollutants present in

the influent did not decrease across the treatment system, the system had

poor removal efficiencies for targeted pollutants, or the effluent

concentrations for particular pollutants did not reflect BPT/BAT level of
10.0 - Long-Term Averages and Variability Factors

10-9

performance. Because pollutants targeted for removal depend on the

pollutants processed at a site and by the treatment technology, EPA

evaluated each treatment system separately, depending on the site

operations and treatment technology. 

Chemical precipitation and sedimentation systems remove metals by

sedimentation of metal hydroxides in the form of suspended solids; poor

removal of total suspended solids (TSS) typically indicates poor removal

of metals in these systems. Therefore, in addition to analyzing for poor

metals removal, EPA identified chemical precipitation systems that did not

have good TSS removal.

C Of the unflagged data, EPA identified four chemical precipitation

systems with poor removal of targeted metals and assigned an “A”

flag to all effluent data associated with these systems.

C EPA assigned an “A” flag to amenable and total cyanide effluent

data for one cyanide destruction unit identified with poor cyanide

removal.

C EPA identified two chemical precipitation systems at two indirect

discharging facilities where the average copper and total suspended

solids effluent concentrations were greater than the current BPT

regulations for these pollutants under 40 CFR 433; therefore,

treatment was not indicative of BPT/BAT for direct dischargers. 

EPA assigned an “A” flag for all copper and total suspended solids

data for these two sites.

C EPA identified two indirect discharging facilities where the

average total suspended solids effluent concentration in the

chemical precipitation system was greater than the current BPT

regulation for total suspended solids under 40 CFR 433; therefore,

treatment was not indicative of BPT/BAT for direct dischargers. 

EPA assigned an “A” flag to effluent data for total suspended

solids for these treatment systems.

C EPA identified four oily waste facilities that were indirect

dischargers and were not required by their publicly owned

treatment works (POTW) to control oil and grease to BPT levels. 

EPA assigned an “A” flag to the effluent data for oil and grease for

these four sites.
10.0 - Long-Term Averages and Variability Factors

10-10

10.2.3 Identification of Process Upsets That Could Affect Data Quality

EPA reviewed sampling episode reports and data for each sampling episode to

identify process upsets occurring on site that could impact treatment efficiency. In this review,

EPA also identified any sampling techniques that could affect the validity of analytical data. 

EPA assigned a flag of “V” to affected pollutants on the days that a system could have been

impacted by a process upset or sampling technique. For example, if a process upset or poor

sampling technique only occurred on one day, EPA assigned only the data for that day a “V” flag,

or if a process upset or poor sampling technique affected only specific pollutants, EPA assigned

only the affected pollutants a “V” flag. Because a treatment system may have been sampled

during multiple sampling episodes and EPA evaluated each episode separately, the Agency may

have flagged a system or pollutant with a “V” during one episode but not for another episode. 

Below are the results of this analysis.

C EPA identified a chemical precipitation system in which site personnel

used barrel finishing wastewater containing iron and aluminum as a

flocculation agent. During two sampling days, site personnel used a

different barrel finishing solution. On those days, the concentration of

metals in the effluent increased, indicating the new solution was not an

effective flocculation agent. EPA assigned a “V” flag to all effluent data 

associated with the two sampling days when the site used the new

solution.

C EPA identified a chemical precipitation system in which the effluent

concentrations of copper were elevated and copper removal efficiencies

were lower than other metals treated by the system. The concentration of

cyanide in the influent system was also elevated compared to cyanide

concentrations typically seen at other MP&M facilities. These data

indicated that the site discharged some copper-cyanide chelates to the

system, affecting the system’s ability to effectively precipitate copper. 

EPA sampled this unit during multiple sampling episodes, and it assigned

a “V” flag to all effluent data for copper during these sampling episodes. 

C EPA identified a chemical precipitation system where the effluent

concentrations of chromium were elevated compared to other metals

treated by the system. The site had a chromium reduction system that EPA

did not sample; however, based on data for hexavalent chromium in the

chemical precipitation system, EPA determined that the chromium

reduction system was not operating optimally during the sampling episode. 

EPA assigned a “V” flag to the chromium data for this chemical

precipitation system.

C EPA identified a chemical precipitation system where the effluent

concentrations of nickel were elevated compared to other metals treated.
10.0 - Long-Term Averages and Variability Factors

10-11

EPA sampled this system during two sampling episodes. The elevated

nickel concentrations indicated that the batch chelation-breaking system

for electroless nickel rinses may not have been operating optimally. The

site combined the electroless nickel treatment sludges with other

wastewater prior to chemical precipitation. The liquid fraction of the

sludge likely contained chelated nickel, which then entered the chemical

precipitation system and could not be efficiently precipitated. EPA

assigned a “V” flag to all nickel effluent data for this treatment unit for

two sampling episodes.

C EPA identified a cyanide destruction system where cyanide samples could

not be preserved until the end of the compositing period. Because some

degradation of cyanide may have occurred during this time, actual values

for cyanide may be higher than the measured value; therefore, EPA could

not accurately evaluate the data. EPA assigned a “V” flag to all cyanide

effluent data for this system during the sampling episode.

C EPA identified a cyanide destruction system where the concentration of

cyanide and metals in the effluent were very high and comparable to those

seen in the influent to treatment systems. The data indicate that the

effluent samples may have been collected at an incorrect location so the

data could not be evaluated for this sampling episode. EPA assigned a

“V” flag to all cyanide effluent data for this system during the sampling

episode.

C EPA identified a chemical oil-emulsion breaking system where site

personnel did not add oil-emulsion breaking polymer on one sampling day. 

On this day, the concentration of oil and grease, total petroleum

hydrocarbons, and total suspended solids was higher in the effluent than

on the other sampling days, indicating that omission of the polymer may

have affected treatment on that day. EPA assigned a “V” flag to oil and

grease, total petroleum hydrocarbons, and total suspended solids effluent

data for that sampling day.

C EPA identified an ultrafiltration system where the concentration of

chromium in the influent was significantly higher on one sampling day

than on the other days, and the concentration increased across the system. 

These data indicated that the site had an unintended discharge of

chromium to the treatment system on that day at concentrations that were

too high for the system to effectively treat. EPA assigned a “V” flag to the

chromium data for the effluent on this sampling day.
10.0 - Long-Term Averages and Variability Factors

10-12

10.2.4 Identification of Wastewater Treatment Chemicals

EPA identified wastewater treatment chemicals used in each of the sampled

treatment systems. EPA assigned a flag of “G” to the treatment chemicals if they did not have

removals comparable to other metals on site, indicating a well-designed and well-operated

system. EPA assigned this flag to 194 effluent data points. Treatment chemicals typically

flagged included sodium, magnesium, aluminum, iron, and calcium. EPA flagged total dissolved

solids along with specific treatment chemicals, because the total dissolved solids concentration

generally increases as a result of treatment chemical addition. 

10.3 Development of Long-Term Averages and Variability Factors

EPA used all unflagged data in the LTA Database to calculate the LTA

concentrations and variability factors that are the basis for the proposed effluent limitations and

standards. EPA calculated LTAs and variability factors from actual concentrations of

constituents measured in MP&M wastewater and treated by MP&M end-of-pipe technology

options (see Section 10.2). As described in Section 10.1, EPA sampling, industry trade

association sampling, and sanitation district sampling episodes at MP&M facilities provided the

data sets of daily effluent concentrations. The following sections discuss development of LTAs

and variability factors (VFs).

For each sampling episode, EPA calculated LTAs for all pollutants that had at

least one sample that passed the data editing review (Section 10.2). The Agency calculated the

LTA for each pollutant as the arithmetic average of the daily concentration values. For samples

where a pollutant was not detected in a sample, EPA used the sample detection limit to calculate

the LTA. EPA calculated the LTA for each pollutant for each subcategory by taking the median

value of the sampling episode LTAs for those episodes within each subcategory. EPA

transferred effluent data from one subcategory to another subcategory when sufficient data were

not available to calculate the limit for a specific pollutant within the original subcategory.

As discussed in Section 7.0, EPA is proposing a limitation for a Total Organics

Parameter (TOP). Table 10-7 lists the priority and nonconventional organics that are included as

part of this parameter. Section 10.4 presents EPA’s methodology for calculating the proposed

TOP limitations. Table 10-8A presents LTAs and VFs for total and amenable cyanide for all

options for the applicable subcategories. Tables 10-8B through 10-8K show LTAs and VFs for

each pollutant for each technology option in each subcategory. Tables 10-9A through 10-9J list

the LTAs, VFs, and limitations for each subcategory.

10.3.1 Derivation of the Proposed Limitations

The limitations and standards are the result of multiplying the LTAs by the

appropriate variability factors. The same basic procedures apply to the calculation of all

limitations and standards for this industry, regardless of whether the technology is BPT, BCT,

BAT, NSPS, PSES or PSNS.
10.0 - Long-Term Averages and Variability Factors

10-13

The limitations for pollutants for each option are provided as ‘daily maximums’

and ‘maximums for monthly averages.’ Definitions provided in 40 CFR 122.2 state that the daily

maximum limitation is the “highest allowable ‘daily discharge’” and the maximum for monthly

average limitation (also referred to as the “monthly average limitation”) is the “highest allowable

average of ‘daily discharges’ over a calendar month, calculated as the sum of all ‘daily

discharges’ measured during a calendar month divided by the number of ‘daily discharges’

measured during that month.” EPA defines daily discharges as the “‘discharge of a pollutant’

measured during a calendar day or any 24-hour period that reasonably represents the calendar day

for purposes of samplings.” 

EPA calculates the limitations based upon percentiles that reflect both the

variability within control of the facility and a level of performance consistent with the Clean

Water Act requirement that these effluent limitations be based on the “best” technologies. The

daily maximum limitation is an estimate of the 99th percentile of the distribution of the daily

measurements. The monthly average limitation is an estimate of the 95th percentile of the

distribution of the monthly averages of the daily measurements.

In establishing daily maximum limitations, EPA’s objective is to restrict the

discharges on a daily basis at a level that is achievable for a facility that targets its (well-operated

and well designed) treatment at the long-term average. EPA acknowledges that variability

around the long-term average results from normal operations. This variability means that

occasionally facilities may discharge at a level that is greater than the long-term average. This

variability also means that facilities may occasionally discharge at a level that is considerably

lower than the long-term average. To allow for these possibly higher daily discharges, EPA has

established the daily maximum limitation. A facility that discharges consistently at a level near

the daily maximum limitation would not be operating its treatment to achieve the long-term

average which is part of EPA’s objective in establishing the daily maximum limitations. 

In establishing monthly average limitations, EPA’s objective is to provide an

additional restriction that supports EPA’s objective of having facilities target their average

discharges to achieve the long-term average. The monthly average limitation requires continuous

dischargers to provide on-going control, on a monthly basis, that complements controls imposed

by the daily maximum limitation. To meet the monthly average limitation, a facility must

counterbalance a value near the daily maximum limitation with one or more values well below

the daily maximum limitation. To achieve compliance, these values must result in a monthly

average value at or below the monthly average limitation. 

In the first of two steps in estimating both types of limitations, EPA determines an

average performance level (the “long-term average” discussed in Section 10.3.4) that a facility

with well-designed and operated model technologies (which reflect the appropriate level of

control) is capable of achieving. This long-term average is calculated from the data from the

facilities using the model technologies for the option. EPA expects that all facilities subject to

the limitations will design and operate their treatment systems to achieve the long-term average
10.0 - Long-Term Averages and Variability Factors

10-14

performance level on a consistent basis because facilities with well-designed and operated model

technologies have demonstrated that this can be done. 

In the second step of developing a limitation, EPA determines an allowance for

the variation in pollutant concentrations when processed through extensive and well designed

treatment systems. This allowance for variance incorporates all components of variability

including treatment process sampling and analytical variability. This allowance is incorporated

into the limitations through the use of the variability factors (discussed in Section 10.3.5) which

are calculated from the data from the facilities using the model technologies. If a facility

operates its treatment system to meet the relevant long-term average, EPA expects the facility to

be able to meet the limitations. Variability factors assure that normal fluctuations in a facility’s

treatment are accounted for in the limitations. By accounting for these reasonable excursions

above the long-term average, EPA’s use of variability factors results in limitations that are

generally well above the actual long-term averages.

Tables 10-9A through 10-9J present the limitations.

10.3.2 Steps Used to Derive Concentration-Based Limitations

The derivation of the concentration-based daily and monthly maximum

limitations uses the pollutant-specific LTAs and respective VFs. The following steps are used to

derive the concentration-based limitations. 

Step 1: Calculate the facility-specific LTAs and 1-day and 4-day VFs for all facilities. 

Calculation of VFs is performed when the facility has four or more observations

with two or more distinct detected values.

Step 2: For each option in the subcategory, calculate the median of the facility-specific

LTAs and the mean of the facility-specific 1-day and 4-day VFs to provide

pollutant-specific LTAs and 1-day and 4-day VFs.

Step 3: Calculate the daily limitations for a pollutant using the product of the pollutantspecific LTA and the pollutant-specific 1-day VF. Calculate monthly average

limitations using the product of the pollutant-specific LTA and the pollutantspecific 4-day VF. 

10.3.3 Modified Delta-Lognormal Model

EPA selected the modified delta-lognormal distribution to model pollutant

effluent concentrations from the MP&M industry in developing the variability factors. A typical

effluent data set from a facility in this industry consists of a mixture of measured (detected) and

nondetected values. Within a data set, gaps between the values of detected measurements and

the sample-specific detection limits associated with nondetected measurements may indicate that

different pollutants were present in the different industrial wastes treated by a facility. 
10.0 - Long-Term Averages and Variability Factors

1Aitchison, J. and Brown, J.A.C. (1963) The Lognormal Distribution. Cambridge University Press, pages 87-99.

10-15

Nondetected measurements may indicate that the pollutant is not generated by a particular source

or industrial process. The modified delta-lognormal distribution is appropriate for such data sets

because it models the data as a mixture of measurements that follow a lognormal distribution and

nondetect measurements that occur with a certain probability. The generalized form of the model

also allows for the possibility that nondetect measurements occur at multiple sample- specific

detection limits. Because the data appear to fit the modified delta-lognormal model reasonably

well, EPA believes this model is an appropriate model for the MP&M industry data.

The modified delta-lognormal distribution is a modification of the ‘delta

distribution’ originally developed by Aitchison and Brown1. The resulting mixed distributional

model, which combines a continuous density portion with a discrete-valued spike at zero, is also

known as the delta-lognormal distribution. The delta in the name refers to the proportion of the

overall distribution contained in the discrete distributional spike at zero, that is, the proportion of

zero amounts. The remaining non-zero, non-censored (NC) values are grouped together and fit

to a lognormal distribution. 

EPA modified this delta-lognormal distribution to incorporate multiple detection

limits. In the modification of the delta portion, the single spike located at zero is replaced by a

discrete distribution made up of multiple spikes. Each spike in this modification is associated

with a distinct sample-specific detection limit associated with nondetected (ND) measurements

in the database. A lognormal density is used to represent the set of measured values. Figure 10-2

shows this modification of the delta-lognormal distribution. 

Figure 10-2. Modified Delta-Lognormal Model

In the modified model, * represents the proportion of NDs, but is divided into the sum of smaller

fractions, *i, each representing the proportion of NDs associated with a particular and distinct

detection limit. Thus it is written as
10.0 - Long-Term Averages and Variability Factors

10-16

(10-1)

(10-2)

(10-3)

(10-4)

(10-5)

If Di equals the value of the ith smallest distinct detection limit in the data set, and the random

variable XD represents a randomly chosen ND sample, then the discrete distribution portion of

the modified delta-lognormal model is mathematically expressed as

EPA uses the following formulas to calculate the mean and variance of this discrete distribution:

10.3.4 Estimation Under the Modified Delta-Lognormal Model

A wide variety of observed effluent data sets fit the modified model. The model

also handles multiple detection limits for NDs. The same basic framework is used even if there

are no ND values or censored data.

U is the modified delta lognormal random variable which combines the discrete

portion of the model with the continuous portion. The following equation expresses the

cumulative probability distribution of the modified delta-lognormal model, where Dk denotes the

largest distinct detection limit observed among the NDs and the first summation is taken over all

those values, Di, that are less than u.

Again combining the discrete and continuous portions of the modified model, the

expected value of the random variable U is derived as a weighted sum of the expected values of

the discrete and continuous lognormal portions of the distribution. This follows because the

modified delta-lognormal random variable U is expressed again as a combination of three other

independent variables, that is,

where this time XD represents a random ND from the discrete portion of the model, XC represents

a random detected measurement from the continuous lognormal portion, and Iu is an indicator
10.0 - Long-Term Averages and Variability Factors

10-17

(10-6)

(10-7)

variable signaling whether any particular random measurement is detected or not. Then the

expected value and variance of U have the form

where Di = detection limit for the ith smallest ND value

Dj = detection limit for the jth smallest ND value, where i < j

*i = proportion of NDs with detection limit = Di

*j = proportion of NDs with detection limit = Dj

* = proportion of all NDs

: = mean log concentrations of NC values

F = standard deviation of log NC values.

10.3.5 Estimation of LTAs and VFs (Data Groups)

To estimate facility-specific long-term averages (LTAs) and variability factors

(VFs), EPA divided the MP&M data sets into two groups based on their size (number of

samples) and the type of samples in the subset because the computations differ for each group. 

EPA defined the groups as follows:

Group 1: Less than 2 NC (detectable) samples or less than 4 total samples at

a facility. Specifically, Group 1 contains all data subsets with all

NDs or only one detect. Sample-specific detection limits are

substituted as the values associated with nondetected pollutants.

Group 2: Two or more NC (detectable) samples and 4 or more total samples.

Sample-specific detection limits are substituted as the values

associated with nondetected pollutants.

10.3.6 Estimation of LTAs

EPA first calculated facility-specific LTAs as the arithmetic average of the

samples using data from Groups 1 and 2. EPA then derived pollutant-specific LTAs from the
10.0 - Long-Term Averages and Variability Factors

10-18

(10-8)

(10-9)

facility-specific LTAs. Pollutant-specific LTAs provide one concentration for a specific

pollutant for all facilities within a subcategory and option. 

Within each subcategory and option combination, EPA calculated pollutantspecific LTAs as the median of the facility-specific LTAs for that pollutant. The median is the

midpoint of the values ordered (i.e., ranked) from smallest to largest. If there is an odd number

of values (with n=number of values), then the value of the (n+1)/2 ordered observation is the

median. If there is an even number of values, then the two values of the n/2 and [(n/2)+1]

ordered observations are arithmetically averaged to obtain the median value. 

10.3.7 Estimation of VFs

EPA developed 1-day and 4-day facility-specific VFs for all regulated pollutants

using Group 2 data only. EPA did not use Group 1 data to estimate VFs because the data were

insufficient for estimating variability using the modified delta-lognormal methodology. 

For Group 2, EPA calculated the parameters for the lognormal portion of the data

using maximum likelihood estimation in the log-domain. Upper percentiles and VFs are

calculated using these estimated parameters. Calculation of these VFs is described in Section

10.3.7.1 and 10.3.7.2.

10.3.7.1 Estimation of 1-day VFs

The 1-day facility-specific VFs are a function of the facility-specific LTA and the

99th percentile. The 99th percentile of each data subset is calculated using the modified deltalognormal methodology by first defining D0=0, *0=0, and Dk+1 = 4 as boundary conditions,

where Di equals the ith smallest detection limit, and *i is the associated proportion of NDs at the

i

th detection limit. A cumulative distribution function, p, for each data subset is computed as a

function ranging from 0 to 1. The general form for p, for a given value c, is

where
10.0 - Long-Term Averages and Variability Factors

10-19

(10-10)

(10-11)

(10-12)

(10-13)

and M is the standard normal cumulative distribution function. EPA calculated the estimated 99th

percentile of each data subset as follows:

1. k values of p at c=Dm, m=1,...k are computed and labeled pm.

2. The smallest value of m, such that pm $ 0.99, is determined and labeled as

pj. If no such m exists, steps 3 and 4 are skipped and step 5 is computed

instead.

3. p

*

 = pj - *j is computed.

4. If p* < 0.99, then P99 = Dj,

else if p* $ 0.99, then 

5. If no such m exists, such that pm $ 0.99 (m=1,...k), then 

The daily VF, VF1, is then calculated as

where 

A pollutant-specific 1-day VF is the mean of the facility-specific daily VFs for

that pollutant in the subcategory and option combination. 
10.0 - Long-Term Averages and Variability Factors

10-20

(10-14)

(10-15)

(10-16)

(10-17)

(10-18)

10.3.7.2 Estimation of 4-day VFs

EPA calculated a facility-specific VF for monthly averages based on the

distribution of 4-day averages. To calculate the 4-day facility-specific VF, EPA assumed that the

approximating distribution of â4, the sample mean for a random sample of four independent

concentration values, also is derived from this modified delta-lognormal distribution with the

same mean as the distribution of the concentration values. The mean of this distribution of 4-day

averages is

where E(X4)D denotes the mean of the discrete portion of the distribution of the average of four

independent concentration values (i.e., when all observations are not detected), and E(X4)C

denotes the mean of the continuous lognormal portion of the distribution. 

First, EPA assumed that the probability of nondetection (*) on each of the four

days is independent of that on the other days, and the nondetected values are therefore not

correlated; consequently, *4 = *

4

. Also, because 

then

and since E(â4) = E(U), then 

The expression for F

2

4

 is derived from the following relationship:

Because

then
10.0 - Long-Term Averages and Variability Factors

10-21

(10-19)

(10-20)

(10-21)

(10-22)

(10-23)

(10-24)

This further simplifies to

and furthermore,

Then, from (10-15) above,

and letting

Furthermore,
10.0 - Long-Term Averages and Variability Factors

10-22

(10-25)

(10-26)

Since Var(â4) = Var(U)/4, then, by rearranging terms,

Thus, estimates of :4 and F4 are derived by using estimates of *1,...*k (sample proportion of NDs

at observed detection limits D1,...Dk), : (maximum likelihood estimate (MLE) of logged values),

and F

2

 (MLE logvariance multiplied by to reflect estimation from sample) in the equations n

n − 1

above.

To find the estimated 95th percentile of the average of four observations, four

NDs, not all at the same detection limit, an average is generated that is not necessarily equal to

D1, D2,..., or Dk. Consequently, more than k discrete points exist in the distribution of the 4-day

averages. For example, the average of four NDs at k=2 detection limits are at the following

discrete points with the associated probabilities:

In general, when all four observations are not detected, and when k detection

limits exist, the multinomial distribution is used to determine associated probabilities; that is,

where ui is the number of nondetected measurements in the data set with the Di detection limit.

The number of possible discrete points, k*, for k=1,2,3,4, and 5 are given below:

k k

*

1 1

2 5

3 15

4 35

5 70
10.0 - Long-Term Averages and Variability Factors

10-23

(10-27)

To find the estimated 95th percentile of the distribution of the average of four

observations, the same basic steps (described in Section 10.3.7.1) as used for the 99th percentile

of the distribution of daily observations are followed, with the following changes:

1. Change P99 to P95, and 0.99 to 0.95.

2. Change Dm to Dm

*

, the weighted averages of the detection limits.

3. Change *i to *i

*

.

4. Change k to k*, the number of possible discrete points based on k detection

limits.

5. Change the estimates of *, :, and F to estimates of *

4

, :4, and F4,

respectively.

Then, the estimate of the 95th percentile 4-day facility-specific mean VF is:

A pollutant-specific 4-day VF is the mean of the facility-specific 4-day VFs for that pollutant in

the subcategory and option combination. 

10.4 Methodology for Development of TOP Long-Term Averages and Variability

Factors

EPA used the following steps to calculate the LTAs and VFs for the Total Organic

Parameter:

C Determine the LTA for each organic component;

C Sum the component LTAs;

C Multiply the total LTA by the mean VF across the individual organic

components; and

C Add the sum of nominal quantitation limits for top pollutants that are not

in the LTA database.

Table 10-7 lists the nominal quantitation values for all of the TOP pollutants and

indicates which TOP pollutants EPA had sufficient data for in its LTA database to calculate an

LTA. For those without data in the LTA database, EPA used the nominal quantitation limit in

calculating the TOP limits. See the Statistical Support Document for Proposed Effluent

Limitations Guidelines and Standards for the Metal Products and Machinery Industry for more

information on the statistical procedures used to develop the TOP limitations.
10.0 - Long-Term Averages and Variability Factors

10-24

Table 10-1

 Number of Evaluated Treatment Systems for Each Subcategory

MP&M End-of-Pipe Technology Option Number of Treatment Units

Cyanide destruction (applies to all subcategories where cyanide is a regulated

pollutant)

13

General Metals Subcategory

Chemical precipitation and clarification using sedimentation (Option 2) 29

Chemical precipitation and clarification using membrane filtration (Option 4) 4

Metal Finishing Job Shop Subcategory 

Chemical precipitation and clarification using sedimentation (Option 2) 6

Printed Wiring Boards Subcategory

Chemical precipitation and clarification using sedimentation (Option 2) 2

Chemical precipitation and clarification using membrane filtration (Option 4) 1

Shipbuilding Drydock Subcategory

DAF 3

Oily Wastes Subcategory

Chemical emulsion breaking and oil-water separation (Option 2) 5

Railroad Line Maintenance Subcategory

DAF (Option 2) 1

Nonchromium Anodizing Subcategory

Chemical precipitation and clarification using sedimentation (Option 2) 2

Source: MP&M LTA Database.
10.0 - Long-Term Averages and Variability Factors

10-25

Table 10-2

Influent and Effluent Data Points from EPA Sampling Episodes

MP&M End-of-Pipe

Technology Option Number of Sitesa

Number of

Sampling

Episodesa

Number of 

Treatment

Units

Number of

Data Pointsb

Chemical precipitation and

clarification using 

sedimentation 

39 42 42 62,892

Chemical precipitation and

clarification using membrane

filtration 

5 5 5 12,824

Ultrafiltration 15 15 16 28,150

DAF 2 3 2 4,872

Chemical emulsion breaking and

oil-water separation

5 5 5 11,926

Cyanide destruction 17 19 17 218

Total 53 57 87 120,882

aEPA conducted multiple sampling episodes at some sites and sampled multiple treatment units at some sites;

therefore, the total does not equal the sum of a column.

bThe database contains 137,823 influent and effluent data points from EPA sampling episodes. For cyanide

destruction, EPA included only data points for amenable and total cyanide in the LTA analysis (to calculate LTAs,

the Agency did not use 16,843 data points associated with analytes other than cyanide across cyanide destruction

treatment units). EPA used data points for organic, metal, conventional, and nonconventional pollutants in the LTA

analysis for treatment units other than cyanide destruction; however, it did not include cyanide (total and amenable)

in the analysis for these other treatment units (98 data points associated with cyanide data across treatment units not

designed for cyanide destruction were not evaluated).

Source: MP&M LTA Database.
10.0 - Long-Term Averages and Variability Factors

10-26

Table 10-3

Influent and Effluent Data Points from Industry and 

Local Sanitation District Sampling Episodes

MP&M End-of-Pipe Technology Option

Number of

Sitesa

Number of

Sampling

Episodesa

Number of 

Treatment

Units

Number of

Data

Pointsb

Chemical precipitation and clarification using

sedimentation

3 4 3 1,752

DAF 2 2 2 2,759

Cyanide destruction 4 5 4 83

Total 5 6 9 4,594

aSanitation districts conducted multiple episodes at some sites and sampled multiple treatment units at some sites;

therefore, the total does not equal the sum of a column.

bThe database contains 6,616 influent and effluent data points from industry and local sanitation district sampling. 

For cyanide destruction, EPA included only data points for amenable and total cyanide in the LTA analysis;

therefore, to calculate LTAs, it did not use 2,022 data points associated with analytes other than cyanide cross

cyanide destruction treatment units. EPA used data points for organic, metal, conventional, and nonconventional

pollutants in the LTA analysis for all treatment units other than cyanide destruction; however, it did not include

cyanide (total and amenable) in the analysis for these other treatment units.

Source: MP&M LTA Database.

Table 10-4

Industry-Supplied Effluent Monitoring Data

Treatment Type Number of Sites

Number of 

Treatment Units

Number of Effluent

Data Points

Chemical precipitation and clarification

using sedimentation 

5 5 2,505

Chemical precipitation and clarification

using membrane filtration 

3 3 708

Ultrafiltration 2 2 393

DAF for oily waste streams 2 2 439

Chemical oil-emulsion breaking 1 1 355

Cyanide destruction 3 3 109

Source: MP&M LTA Database.
10.0 - Long-Term Averages and Variability Factors

10-27

Table 10-5

Number of Effluent Data Points Flagged for Each MP&M Technology Option

MP&M End-of-Pipe

Technology Option

Number of 

Effluent Data

Points Evaluated a

Number of Flagged Effluent Data Points

Number of

Unflagged

Effluent Data

N C F LC LA 1 2 O P A V G Points

Chemical Precipitation with

Membrane Filtration

2,856 2,061 453 10 35 12 0 0 0 0 10 0 55 220

Chemical Precipitation with

Sedimentation

15,743 9,091 3,665 36 259 0 147 109 33 155 178 40 309 1,721

Cyanide Destruction 151 2 19 0 4 0 0 5 1 10 1 13 0 96

Ultrafiltration 6,442 3,828 1,044 8 163 35 0 0 0 0 0 1 0 1,363

Chemical Emulsion

Breaking and Oil/Water

Separation

2,626 1,492 519 25 51 0 0 8 0 0 14 3 47 475

DAF 1,754 1,013 444 6 25 10 0 0 0 0 0 0 29 227

Total 29,572 17,487 6,144 85 537 57 147 122 34 165 203 57 440 4,102

a

 EPA only evaluated data for pollutants of concern. Data for cyanide destruction units are for amenable and total cyanide only. Data points for treatment units (other than cyanide

destruction) are for priority metals and organics, nonconventional metals and organics, and conventional and nonconventional pollutant parameters, and exclude cyanide data. 

Section 7.0 lists the pollutants of concern.
10.0 - Long-Term Averages and Variability Factors

10-28

Table 10-6A

 MP&M Technology Effectiveness Concentrations for

 Total and Amenable Cyanide Destructiona

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration 

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Total Cyanide

4274 CBI CBI CBI CBI CBI 0.01 0.01 0.01 --- ---

4279 9.9 7.6 11.0 50.0 48.0 0.01 0.01 0.01 0.01 0.01

4384 CBI CBI CBI CBI CBI 0.99 0.69 0.76 0.94 0.46

4460A --- 21.1 --- --- --- --- 0.02 --- --- ---

4807 --- 0.077 47.8 4.25 0.094 0.021 0.028 0.047 0.020 0.020

4817 345 368 371 394 --- 0.58 0.81 0.20 0.61 0.02

4828 --- --- 8.64 17.9 2.99 0.062 0.180 0.092 0.076 0.049

4834 CBI CBI CBI CBI CBI 0.02 0.02 0.02 0.02 0.02

4847 0.024 2.3 0.026 0.01 3.22 --- 0.019 0.010 0.010 0.010

4891 CBI CBI CBI CBI CBI 0.056 0.110 0.044 0.071 0.160

4904 6.33 12.70 6.80 10.90 7.29 0.175 0.117 0.325 0.309 0.359

6048 7.38 9.72 6.59 5.14 10.40 0.17 0.30 0.19 0.17 0.20

6186 97.7 66.2 69.0 75.3 102.0 0.13 0.20 0.21 0.24 0.20

Amenable Cyanide

4807 --- 0.077 47.7 4.25 0.02 0.02 0.02 0.02 0.02 0.02

4817 345 368 371 394 --- 0.58 0.81 0.20 0.58 ---

4828 --- --- 8.62 17.40 2.91 0.035 0.160 0.063 0.038 0.024

4834 CBI CBI CBI CBI CBI 0.02 0.02 0.02 0.02 0.02

4847 0.01 2.21 0.03 0.01 3.15 --- 0.01 0.01 0.01 0.01

4904 6.33 12.50 6.53 10.30 4.43 0.162 0.073 0.143 0.134 0.082

6048 6.96 9.21 6.13 4.87 9.60 0.02 0.037 0.005 0.005 0.014

6186 97.4 65.7 68.5 74.8 102.0 0.049 0.022 0.017 0.110 0.110

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-29

Table 10-6B

MP&M Technology Effectiveness Concentrations for

General Metals and Steel Forming and Finishing Subcategories (Option 2)a,b

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Oil and Grease

4737 CBI CBI CBI CBI CBI 14.4 16.5 14.1 10.0 13.0

4871 114.0 53.1 39.9 92.0 37.4 6.02 6.22 6.17 6.12 6.15

Total Suspended Solids (TSS)

1197A 12 54 260 --- --- 28.0 20.0 32.0 --- ---

4011 CBI CBI CBI CBI CBI 28.0 30.0 22.0 --- ---

4079 CBI CBI CBI CBI CBI 9.0 5.0 5.0 --- ---

4277 320 20 11 13 16 14.0 14.0 17.0 10.0 17.0

4384 CBI CBI CBI CBI CBI 50.0 32.0 55.0 23.0 68.0

4415 --- 77.1 119.0 130.6 --- --- 1.0 1.0 1.0 —

4417 430 70 32 22 4 12.0 10.0 7.0 4.0 2.0

4438 410 --- --- 10 11 7.0 --- --- 8.0 5.0

4470 CBI CBI CBI CBI CBI 14.5 10.0 10.0 22.0 32.0

4737 CBI CBI CBI CBI CBI 20.0 14.5 35.0 12.5 38.0

4761 CBI CBI CBI CBI CBI 17.0 24.0 25.0 --- ---

4762 CBI CBI CBI CBI CBI 14.0 16.0 13.0 16.0 13.0

4807 172 150 144 124 124 6.0 16.0 7.5 8.0 4.0

4811 CBI CBI CBI CBI CBI 4.0 4.0 4.0 4.0 4.0

4817 46 14 66 108 61 8.0 4.0 21.0 18.0 8.0

4833 115 150 129 244 230 6.5 7.0 17.5 5.5 5.5

4834 CBI CBI CBI CBI CBI 4 14 4 44 7

4871 724 538 193 647 258 7 8 6 4 4

4904 6230 8080 8920 7520 6240 4.5 4.0 4.0 8.5 7.5

Manganese

4762 CBI CBI CBI CBI CBI 0.168 0.165 0.097 0.130 0.134

4807 0.446 0.358 0.469 1.60 1.31 0.030 0.047 0.040 0.071 0.061

4871 8.67 7.83 3.97 10.10 5.49 0.103 0.104 0.088 0.076 0.087

4904 3.53 6.11 5.20 5.69 4.33 0.0144 0.0209 0.0132 0.0079 0.0097
Table 10-6B (Continued)

10.0 - Long-Term Averages and Variability Factors

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

10-30

Molybdenum

4806 1.15 1.15 1.27 0.592 1.16 1.44 0.639 0.501 0.665 0.371

4904 0.634 1.28 1.39 1.5 0.942 0.028 0.034 0.036 0.031 0.027

Tin

4817 6.33 4.65 5.17 13.9 6.92 0.034 0.030 0.028 0.086 0.122

4834 CBI CBI CBI CBI CBI 0.59 0.57 0.72 1.37 0.82

Total Organic Carbon (TOC) (as indicator parameter)

4737 CBI CBI CBI CBI CBI 75 106 71 108 71

4761 CBI CBI CBI CBI CBI 52 46 51 --- ---

4762 CBI CBI CBI CBI CBI 172 180 147 182 172

4806 8.26 12.9 13.8 12.5 27.9 29.3 12.9 9.3 37.0 20.4

4807 20.2 26.3 17.4 17.3 24.1 16.2 23.6 27.4 10.2 8.91

4817 29.6 29.6 51.3 57.4 47.3 16.4 17.4 21.6 25.7 31.7

4833 26 41 73 10 22 10 12 34 10 10

4834 CBI CBI CBI CBI CBI 87.1 77.9 90.7 67.6 42

4871 174 102 149 206 124 117 87 117 91 101

4904 10 24 10 10 18 10 10 10 10 10

Cadmium

1197A --- 1.49 0.271 --- --- --- 0.08 0.06 --- ---

4277 18.9 3.42 0.903 2.93 5.27 0.230 0.202 0.0779 0.140 0.219

4415 --- 0.443 0.0358 0.0483 --- --- 0.005 0.005 0.005 ---

4460 0.068 0.347 0.141 --- --- 0.021 0.049 0.035 --- ---

6048 13.9 21.6 8.50 6.56 6.73 0.857 1.09 0.942 0.765 0.801

Chromium

1197A 28.7 1.4 0.027 --- --- 1.23 0.656 0.027 --- ---

4011 CBI CBI CBI CBI CBI 0.756 0.726 1.13 --- ---

4079 CBI CBI CBI CBI CBI 0.635 1.82 0.456 --- ---

4310 CBI CBI CBI CBI CBI 0.395 1.77 4.65 --- —

4330 CBI CBI CBI CBI CBI 0.066 0.131 0.043 0.050 0.043

4384 CBI CBI CBI CBI CBI 0.593 0.603 0.785 0.411 0.532

4415 --- 5.303 1.475 0.973 --- --- 0.015 0.020 0.112 ---

4417 5.10 3.31 3.56 2.77 1.57 0.0199 0.0133 0.0292 0.0098 0.0216
Table 10-6B (Continued)

10.0 - Long-Term Averages and Variability Factors

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

10-31

Chromium (continued)

4438 28.1 --- --- 17.4 19.3 0.099 --- --- 0.091 0.088

4460 4.24 8.8 3.06 --- --- 1.33 1.21 0.984 --- ---

4470 CBI CBI CBI CBI CBI 0.0825 0.0555 0.0686 0.1083 0.0716

4811 CBI CBI CBI CBI CBI 0.008 0.008 0.008 0.010 0.009

4817 2.73 2.55 2.15 0.33 1.64 0.0576 0.314 0.0805 0.0217 0.2715

4833 8.85 19.1 18.1 62.2 37.4 0.0369 0.0281 0.0675 0.0891 0.118

4847 8.32 8.07 28.7 10.0 102 0.380 0.201 0.194 0.190 0.543

4871 1.54 0.82 0.41 1.57 0.515 0.01 0.01 0.01 0.01 0.01

4904 7.7 12.1 15.6 14.8 11.0 0.017 0.012 0.011 0.022 0.012

Copper

4277 29.50 7.74 5.16 13.1 14.6 0.638 0.701 0.610 0.462 0.385

4737 CBI CBI CBI CBI CBI 0.507 0.235 0.022 0.040 0.073

4806 13.6 8.57 8.18 4.47 1.66 1.07 0.265 0.301 0.926 0.484

4807 29.5 27.7 23.0 22.4 23.5 1.31 1.43 1.36 0.71 0.426

4817 32.8 30.0 32.6 36.8 30.1 0.199 0.149 0.154 0.260 0.428

4833 0.402 1.48 2.91 3.70 2.63 0.110 0.127 0.098 0.131 0.175

4834 CBI CBI CBI CBI CBI 0.0519 0.0454 0.0477 0.0772 0.0796

4847 1.65 2.43 3.57 0.944 1.03 0.118 0.100 0.103 0.035 0.046

4904 157 251 251 273 224 0.037 0.040 0.031 0.049 0.073

Lead

1197A 0.20 0.223 159 --- --- 0.47 4.97 0.20 --- ---

4761 CBI CBI CBI CBI CBI 0.012 0.012 0.012 --- ---

4762 CBI CBI CBI CBI CBI 0.0248 0.0248 0.0248 0.0248 0.0248

4834 CBI CBI CBI CBI CBI 0.0256 0.016 0.0181 0.0186 0.0244

4871 1.47 1.95 1.04 1.80 1.12 0.0087 0.0130 0.011 0.0061 0.0083

Nickel

1197A 0.082 6.29 0.071 --- --- 0.209 1.390 1.390 --- ---

4277 27.4 2.705 1.05 3.54 6.38 0.173 0.180 0.161 0.180 0.197

4438 34.2 --- --- 32.4 31.7 0.378 --- --- 0.518 0.348

4470 CBI CBI CBI CBI CBI 0.339 0.229 0.143 0.222 0.224

4761 CBI CBI CBI CBI CBI 0.319 0.254 0.225 --- ---

4762 CBI CBI CBI CBI CBI 0.304 0.232 0.124 0.158 0.211

4807 6.56 5.73 6.67 6.90 5.95 0.287 0.354 0.319 0.220 0.138
Table 10-6B (Continued)

10.0 - Long-Term Averages and Variability Factors

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

10-32

4811 CBI CBI CBI CBI CBI 0.0160 0.057 0.063 0.018 0.037

Nickel (continued)

4817 0.209 0.329 0.721 0.944 1.38 0.0209 0.0284 0.0282 0.0472 0.0473

4833 0.507 0.651 0.724 0.864 5.02 0.192 0.016 0.016 0.016 0.016

4834 CBI CBI CBI CBI CBI 0.212 0.216 0.310 0.430 0.484

4847 0.639 0.918 2.64 1.52 0.43 0.043 0.031 0.027 0.061 0.110

4871 8.97 8.48 4.70 10.3 6.11 0.697 0.620 0.602 0.536 0.802

4904 6.60 11.4 10.8 12.4 8.99 0.026 0.026 0.026 0.026 0.026

6048 0.718 22.4 4.56 8.95 21.2 0.135 0.518 0.270 0.284 0.525

Silver

1197A 0.005 3.2 0.029 --- --- 0.559 0.430 0.029 --- ---

4277 4.230 0.138 0.0165 0.121 0.303 0.005 0.005 0.010 0.005 0.027

4807 0.999 1.670 1.010 0.683 0.923 0.0202 0.0472 0.0701 0.0006 0.0218

4817 0.910 0.793 1.040 0.946 0.548 0.0160 0.0782 0.051 0.0613 0.1025

Zinc

1197A --- 0.153 0.062 --- --- --- 0.041 0.020 --- ---

4277 3.48 1.335 0.925 0.801 2.64 0.0218 0.0469 0.0416 0.0126 0.0153

4415 --- 2.303 1.923 3.012 --- --- 0.070 0.058 0.541 ---

4417 142 66.1 45.9 4.55 19.9 0.15 0.213 0.173 0.0778 0.212

4470 CBI CBI CBI CBI CBI 1.596 0.98 1.35 1.18 1.792

4737 CBI CBI CBI CBI CBI 0.0655 0.0882 0.386 0.0557 0.0926

4761 CBI CBI CBI CBI CBI 0.136 0.140 0.2015 --- ---

4762 CBI CBI CBI CBI CBI 0.269 0.175 0.173 0.163 0.224

4807 4.13 3.97 4.19 3.56 3.02 0.137 0.165 0.194 0.097 0.051

4811 CBI CBI CBI CBI CBI 0.0521 0.0556 0.0629 0.0473 0.0468

4817 57.6 55.5 30.6 51.5 23.4 0.447 0.300 0.196 0.411 0.309

4871 32 25.7 13 34.9 17.5 0.203 0.215 0.139 0.126 0.141

4904 3.91 6.21 4.62 4.21 3.03 0.015 0.018 0.015 0.015 0.015

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

bThe Steel Forming and Finishing Subcategory has mass-based limits, which are being proposed based on the

General Metals Subcategory concentration-based limits. Section 14.0 provides the mass-based limits for the Steel

Forming and Finishing Subcategory and methodology for deriving the limits.

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-33

Table 10-6C

MP&M Technology Effectiveness Concentrations for

General Metals and Steel Forming and Finishing Subcategory (Option 4)a,b

Episode

Daily Influent Concentration 

(mg/L, ppm)

Daily Effluent Concentration 

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Cadmium

4882 3.59 4.52 3.82 3.18 1.27 0.0072 0.005 0.0056 0.0073 0.0102

Chromium

4807 0.71 0.164 0.51 0.412 1.24 0.085 0.0154 0.0368 0.0248 0.017

4854 CBI CBI CBI CBI CBI 0.0098 0.0119 0.0170 0.0142 0.017

4882 35.3 23.0 25.4 24.1 11.0 0.0159 0.0330 0.0867 0.0954 0.468

Copper

4807 17.2 9.71 26.6 20.7 89.8 0.127 0.0416 0.0418 0.0663 0.0929

4854 CBI CBI CBI CBI CBI 0.008 0.008 0.034 0.330 0.0394

4882 1.5 0.74 0.432 0.372 0.219 0.0660 0.0205 0.0168 0.0124 0.0126

Manganese

4807 4.78 1.16 4.19 1.51 5.95 0.117 0.132 0.162 0.171 0.067

Nickel

4807 29.0 5.06 12.3 6.94 30.9 1.58 0.48 0.55 0.54 0.60

4854 CBI CBI CBI CBI CBI 0.022 0.016 0.017 0.016 0.101

Silver

4807 3.13 1.79 3.39 1.92 2.48 0.0184 0.0006 0.0331 0.0252 0.0006

Tin

4807 0.394 1.74 2.17 0.60 1.29 0.0184 0.0184 0.0184 0.0184 0.0184

Zinc

4807 9.01 3.01 7.91 4.39 13.4 0.0576 0.0584 0.0398 0.0452 0.0002

4854 CBI CBI CBI CBI CBI 0.008 0.017 0.020 0.008 0.008

4882 34.8 44.6 37.8 32.7 14.0 0.028 0.029 0.067 0.046 0.011

Total Suspended Solids (TSS)

4807 3080 152 2380 380 2920 30.0 17.0 23.0 13.0 27.0

4882 33 61 76 --- 22 4.5 4.0 4.0 4.0 4.0

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

bThe Steel Forming and Finishing Subcategory has mass-based limits, which are being proposed based on the

General Metals Subcategory concentration-based limits. Section 14.0 provides the mass-based limits for the Steel

Forming and Finishing Subcategory and methodology for deriving the limits.

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-34

Table 10-6D

MP&M Technology Effectiveness Concentrations for

Metal Finishing Job Shops Subcategory (Option 2)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Total Suspended Solids (TSS)

4788 175.2 97.6 86.8 103.2 708.8 13.0 21.0 12.0 6.5 9.0

6178 250.5 534 170.5 --- --- 16 43 10 --- ---

6187 6266.5 6307.5 8532.5 --- --- 10.5 12.0 11.0 --- ---

Manganese

4278 CBI CBI CBI CBI CBI 0.181 0.166 0.115 0.172 ---

4279 2.176 1.033 1.236 0.620 5.713 0.035 0.093 0.076 0.007 0.195

6178 0.5005 1.6975 1.7425 --- --- 0.0127 0.0216 0.0167 --- ---

6187 9.4873 17.312 47.339 --- --- 0.0043 0.0036 0.0064 --- ---

Tin

4788 50.95 36.51 63.67 52.71 75.34 1.08 0.94 1.36 1.46 1.22

Total Organic Carbon (TOC) (as indicator parameter)

4788 36.4 37.0 57.6 39.6 46.4 48.0 42.0 68.5 50.5 43.0

Cadmium

4279 7.6391 2.6358 2.4367 1.4307 7.7302 0.0864 0.1756 0.2105 0.0222 0.1896

4788 1.3988 3.436 1.9368 2.1336 11.5484 0.0118 0.0427 0.0225 0.0105 0.0198

6178 2.9685 0.9908 1.6622 --- --- 0.041 0.035 0.029 --- ---

6187 63.935 117.034 322.825 --- --- 0.0286 0.0707 0.0661 --- ---

Chromium

4278 CBI CBI CBI CBI CBI 0.019 0.007 0.007 0.033 ---

4279 22.559 11.269 9.668 7.609 10.352 0.364 0.507 0.576 0.180 0.834

4788 5.568 8.062 13.198 11.907 10.887 0.336 0.188 0.475 0.236 0.05

4893 0.269 1.82 --- --- --- 0.126 0.382 --- --- ---

6178 1.084 1.82 4.365 --- --- 0.141 0.282 0.626 --- ---

6187 14.358 31.745 93.393 --- --- 0.169 0.478 0.396 --- ---

Copper

4278 CBI CBI CBI CBI CBI 0.035 0.329 0.087 0.061 ---

4279 3.663 1.8121 1.1632 0.9302 2.1929 0.0990 0.1235 0.1748 0.0344 0.0929

4883 0.998 1.160 1.06 0.645 1.04 0.176 0.596 0.358 0.407 0.304

4894 0.904 1.14 --- --- --- 0.463 0.253 --- --- ---
Table 10-6D (Continued)

10.0 - Long-Term Averages and Variability Factors

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

10-35

Copper (continued)

6178 5.74 23.875 17.0 --- --- 0.221 0.653 0.439 --- ---

6187 122.18 201.475 344.128 --- --- 0.420 0.208 0.277 --- ---

Lead

4788 8.314 8.074 9.726 11.084 16.168 0.165 0.127 0.152 0.244 0.196

6178 2.840 13.595 19.643 --- --- 0.035 0.070 0.055 --- ---

6187 36.585 72.053 74.443 --- --- 0.084 0.044 0.075 --- ---

Nickel

4278 CBI CBI CBI CBI CBI 0.318 0.157 0.317 0.596 ---

4279 7.141 3.847 2.619 3.537 13.153 0.477 0.481 0.363 0.058 0.527

4788 21.267 13.464 16.572 15.403 53.733 0.690 0.790 0.748 0.679 0.342

4883 2.05 0.786 3.36 1.99 0.605 0.315 0.205 0.534 0.465 0.182

4894 1.71 1.12 --- --- --- 0.305 0.233 --- --- ---

Silver

4788 0.3122 0.4425 0.1738 0.2374 1.4206 0.0296 0.0296 0.0068 0.005 0.0196

6178 0.2425 1.6425 2.0275 --- --- 0.035 0.010 1.080 --- ---

6187 0.9715 0.8013 1.146 --- --- 0.043 0.033 0.020 --- ---

Zinc

4278 CBI CBI CBI CBI CBI 0.022 0.027 0.011 0.011 ---

4279 93.67 40.33 34.26 44.99 100.47 1.23 3.53 2.06 0.263 2.87

4788 1.099 2.074 1.610 1.260 4.907 0.011 0.032 0.024 0.011 0.013

4883 0.996 1.13 0.837 1.10 0.592 0.177 0.269 0.230 0.322 0.164

4893 0.292 1.67 --- --- --- 0.087 0.352 --- --- ---

4894 0.532 1.40 --- --- --- 0.114 0.255 --- --- ---

6178 1.3842 0.813 0.9343 --- --- 0.0463 0.0169 0.0161 --- ---

6187 19.2285 69.7393 175.9742 --- --- 0.0177 0.0162 0.0221 --- —

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2). Section 14.0 provides the

mass-based limits for the Steel Forming and Finishing Subcategory and methodology for deriving the limits.

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-36

Table 10-6E

MP&M Technology Effectiveness Concentrations for

Nonchromium Anodizers Subcategory (Option 2)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Total Suspended Solids (TSS)

4856 CBI CBI CBI CBI CBI 7.0 6.0 6.0 8.0 11.0

4869 502 21 9 46 --- 4.0 12.0 10.0 52.0 4.0

Aluminum

4856 CBI CBI CBI CBI CBI 2.91 2.23 3.04 3.4 5.29

4869 132 14.8 16.1 8.24 --- 1.08 0.64 1.14 4.65 0.80

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.

Table 10-6F

MP&M Technology Effectiveness Concentrations for

Printed Wiring Boards Subcategory (Option 2)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Manganese

4866 0.385 0.574 0.860 1.940 1.070 0.212 0.235 0.289 0.666 0.641

Nickel

4866 2.5 0.499 0.325 0.449 0.279 0.121 0.148 0.091 0.107 0.090

4867 0.0388 0.029 2.30 0.372 0.505 0.017 0.016 0.126 0.019 0.067

Tin

4866 6.74 3.89 5.07 4.11 4.92 0.051 0.141 0.082 0.097 0.229

4867 3.26 5.13 2.65 1.61 1.71 0.025 0.093 0.016 0.014 0.039

Total Organic Carbon (TOC) (as indicator parameter)

4866 11.2 22.1 17.7 62.0 16.6 11.0 17.7 16.5 35.6 13.8

4867 87.6 152 116 86.3 108 70.7 86.1 99.7 84.4 88.4

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-37

Table 10-6G

MP&M Technology Effectiveness Concentrations for

Printed Wiring Boards Subcategory (Option 4)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Copper

4855 19.4 48.8 38.6 16.9 33.9 0.0018 0.0018 0.0018 0.0018 0.0081

Lead

4855 3.1 2.61 2.38 2.18 1.75 0.021 0.021 0.021 0.021 0.021

Tin

4855 6.94 5.77 4.48 4.35 2.97 0.0403 0.0718 0.0548 0.0549 0.0517

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.

Table 10-6H

MP&M Technology Effectiveness Concentrations for

 Oily Wastes Subcategory (Option 6)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Oil and Grease (as HEM)

4851 6883.8 16642 379.5 7569.7 334 14.9 18.3 15.4 14.2 12.1

4872 696.0 2182.5 502.0 --- --- 52.0 44.8 55.6 --- ---

4876 2030 2230 1760 1110 3440 25.6 24.7 105 54.7 188

4877 556.5 1937.5 996.7 544.3 469 24.0 63.75 14.75 21.25 15.0

Total Sulfide (as S)

4877 14.0 5.0 4.0 14.0 17.0 4.5 8.0 3.0 17.0 3.0

Total Suspended Solids (TSS)

4471 96 82 77 98 --- 100 40 36 6 ---

4851 1720 508 373 615 71 40 35 49 48 34

4872 244 242 165 --- --- 12.5 10.0 13.0 --- ---

4876 1670 833 1580 84 620 18 15 20 10 12

4877 90 275 162 303 241 17 62 26 14 21
Table 10-6H (Continued)

10.0 - Long-Term Averages and Variability Factors

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

10-38

Total Organic Carbon (TOC) (as indicator parameter)

4851 1520 517 280 216 232 202.0 254.5 299.5 480.0 240.0

4872 1340 963 797 --- --- 173.5 131 260 --- ---

Total Organic Carbon (TOC) (as indicator parameter) - (continued)

4876 928 1090 1690 1120 1650 493 313 1110 605 1270

4877 659 158 289 569 282 269 206.5 264 329 269

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.

Table 10-6I

MP&M Technology Effectiveness Concentrations for

Railroad Line Maintenance Subcategory (Option 10)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Biochemical Oxygen Demand (BOD) 5-Day (Carbonaceous)

6179 114 94 256 --- --- 4.5 5.0 6.0 --- ---

Oil and Grease (as HEM)

6179 255.5 250.7 268 --- --- 6.7 6.7 5.3 --- ---

Total Suspended Solids (TSS)

6179 122 155 339 --- --- 14.5 8.5 9.0 --- ---

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-39

Table 10-6J

MP&M Technology Effectiveness Concentrations for

Shipbuilding and Drydock Subcategory (Option 10)a

Episode

Daily Influent Concentration

(mg/L, ppm)

Daily Effluent Concentration

(mg/L, ppm)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 1 Day 2 Day 3 Day 4 Day 5

Oil and Grease (as HEM)

4891 CBI CBI CBI CBI CBI 5.6 5.5 8.3 5.3 6.3

4892 180.3 206.8 595.5 661.3 1823 9.3 8.5 12.0 11.7 17.2

Total Suspended Solids (TSS)

4805 1070 9 --- --- --- 38 21 --- --- —

4891 CBI CBI CBI CBI CBI 17 11 5 18 7

4892 39 47 50 88 221 37.5 41 44.5 50 102

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

--- No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-40

Table 10-7 

Calculation of Total Organics Parameter (TOP) Limit

Total Organics Parameter Pollutants 

that are also POCs CAS Number

Nominal

Quantitation

Limit (mg/L)

Pollutant has data in

the LTA database

for Option 2a

Acrolein

Benzoic acid 

Carbon disulfide

Dibenzofuran

Dibenzothiophene

Isophorone

n-Hexadecane

n-Tetradecane

107-02-8

65-85-0

75-15-0

132-64-9

132-65-0

78-59-1

544-76-3

929-59-4

0.05

0.05

0.01

0.01

0.01

0.01

0.01

0.01

x

x

x

x

x

Aniline 62-53-3 0.01

Chloroform (trichloromethane)

Methylene chloride (dichloromethane)

67-66-3

75-09-2

0.01

0.01

x

Chloroethane (ethyl chloride)

1,1-Dichloroethane

1,1,1-Trichloroethane 

(methylchloroform)

75-00-3

75-34-3

71-55-6

0.05

0.01

0.01

1,1-Dichloroethylene (vinylidene 

chloride)

Tetrachloroethylene (perchloroethylene)

Trichloroethylene

75-35-4

127-18-4

79-01-6

0.01

0.01

0.01

x

Biphenyl

p-Cymene

Ethylbenzene

Toluene

92-52-4

99-87-6

100-41-4

108-88-3

0.01

0.01

0.01

0.01

x

x

x

x

N-Nitrosodimethylamine

N-Nitrosodiphenylamine

62-75-9

86-30-6

0.05

0.02

Chlorobenzene 108-90-7 0.01

2,6-Dinitrotoluene 606-20-2 0.01

Phenol

4-Chloro-m-cresol (parachlorometacresol 

or 4-chloro-3- methylphenol)

2,4-Dinitrophenol

2,4-Dimethylphenol

2-Nitrophenol (o-nitrophenol)

4-Nitrophenol (p-nitrophenol)

108-95-2

59-50-7

51-28-5

105-67-9

88-75-5

100-02-7

0.01

0.01

0.05

0.01

0.02

0.05

x
Table 10-7 (Continued)

10.0 - Long-Term Averages and Variability Factors

Total Organics Parameter Pollutants 

that are also POCs CAS Number

Nominal

Quantitation

Limit (mg/L)

Pollutant has data in

the LTA database

for Option 2a

10-41

Acenaphthene

Anthracene

3,6-Dimethylphenanthrene 

Fluorene

Fluoranthene

2-Isopropylnaphthalene 

1-Methylfluorene 

2-Methylnaphthalene 

1-Methylphenanthrene 

Naphthalene

Phenanthrene

Pyrene

83-32-9

120-12-7

1576-67-6

86-73-7

206-44-0

2027-17-0

1730-37-6

91-57-6

832-69-9

91-20-3

85-01-8

129-00-0

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

x

x

x

x

x

x

x

x

x

x

Benzyl butyl phthalate

Dimethyl phthalate

Di-n-butyl phthalate

Di-n-octyl phthalate

Di(2-ethylhexyl) phthalate

85-68-7

131-11-3

84-74-2

117-84-0

117-81-7

0.01

0.01

0.01

0.01

0.01 x

Sum of nominal quantitation limits for

pollutants that are not in the LTA database

0.47

a

 x indicates that the pollutant has data in the LTA database for Option 2. 
10.0 - Long-Term Averages and Variability Factors

10-42

Table 10-8A

Episode-Level Long-Term Averages and Variability Factors for

 Total and Amenable Cyanide Destruction

(All Options for Applicable Subcategories)a

Regulated

Pollutant Subcategory Episode

Long-Term

Average

Concentration

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Total Cyanide General Metals 4274 0.01 --- ---

Metal Finishing

Job Shop

4279 0.01 --- ---

General Metals 4384 0.77 1.94 1.27

General Metals 4460A 0.02 --- ---

General Metals 4807 0.027 2.60 1.41

General Metals 4817 0.443 2.18 1.60

Metal Finishing

Job Shop

4828 0.092 2.80 1.48

General Metals 4834 0.02 --- ---

General Metals 4847 0.012 2.63 1.39

Shipbuilding

and Drydock

4891 0.088 2.92 1.51

General Metals 4904 0.257 2.74 1.47

General Metals 6048 0.207 1.66 1.20

Metal Finishing

Job Shop

6186 0.196 1.67 1.20

Amenable

Cyanide

General Metals 4807 0.02 --- ---

General Metals 4817 0.54 1.83 1.37

Metal Finishing

Job Shop

4828 0.064 4.20 1.79

General Metals 4834 0.020 --- ---

General Metals 4847 0.010 --- ---

General Metals 4904 0.119 2.14 1.33

General Metals 6048 0.016 3.70 1.76

Metal Finishing

Job Shop

6186 0.0618 5.12 1.99

aData used for limits for General Metals, Metal Finishing Job Shops, Printed Wiring Board, and Steel Forming and

Finishing Subcategories.
10.0 - Long-Term Averages and Variability Factors

10-43

Table 10-8B

Episode-Level Long-Term Averages and Variability Factors for

General Metals and Steel Forming and Finishing Subcategories (Option 2) a

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor

4-Day Variability

Factor

Manganese 4762 0.139 1.64 1.20

4807 0.050 2.08 1.31

4871 0.092 1.35 1.11

4904 0.013 2.22 1.35

Molybdenum 4806 0.723 2.84 1.49

4904 0.031 1.32 1.11

Tin 4817 0.060 3.85 1.72

4834 0.815 2.14 1.32

Total Organic Carbon (TOC)

(as indicator parameter)

4737 86.5 1.61 1.19

4761 49.7 --- ---

4762 170.6 1.22 1.07

4806 21.8 3.20 1.57

4807 17.3 2.80 1.48

4817 22.6 1.82 1.24

4833 15.2 5.15 1.95

4834 73.1 1.97 1.28

4871 102.6 1.37 1.12

4904 10.0 --- ---

Cadmium 1197A 0.0705 --- ---

4277 0.174 2.59 1.43

4415 0.0052 --- ---

4460 0.0349 --- ---

6048 0.891 1.37 1.12

Chromium 1197A 0.638 --- ---

4011 0.871 --- ---

4079 0.970 --- ---

4310 2.272 --- ---

4330 0.067 2.65 1.45

4384 0.585 1.68 1.21

4415 0.0488 --- ---
Table 10-8B (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor

4-Day Variability

Factor

10-44

Chromium (continued) 4417 0.0188 2.47 1.41

4438 0.093 --- ---

4460 1.175 --- ---

4470 0.0773 1.73 1.22

4811 0.0085 1.19 1.07

4817 0.0925 6.02 2.19

4833 0.0679 3.37 1.61

4847 0.301 2.73 1.46

4871 0.0101 --- ---

4904 0.0147 1.91 1.27

Copper 4277 0.559 1.73 1.22

4737 0.175 8.73 2.82

4806 0.609 3.58 1.66

4807 1.049 2.98 1.52

4817 0.238 2.50 1.41

4833 0.128 1.63 1.19

4834 0.060 1.81 1.24

4847 0.080 3.05 1.54

4904 0.046 2.03 1.30

Lead 1197A 1.88 --- ---

4761 0.012 --- ---

4762 0.025 --- ---

4834 0.020 1.55 1.18

4871 0.009 1.88 1.26

Nickel 1197A 0.557 --- ---

4277 0.178 1.18 1.06

4438 0.415 --- ---

4470 0.231 1.95 1.28

4761 0.266 --- ---

4762 0.206 2.11 1.32

4807 0.264 2.24 1.35

4811 0.047 1.93 1.36

4817 0.034 2.16 1.33

4833 0.051 --- ---

4834 0.330 2.26 1.35

4847 0.054 3.16 1.56

4871 0.652 1.41 1.13

4904 0.026 ---- ----

6048 0.346 3.15 1.56
Table 10-8B (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor

4-Day Variability

Factor

10-45

Silver 1197A 0.339 ---- ---

4277 0.010 5.89 2.13

4807 0.032 4.02 1.84

4817 0.062 4.08 1.76

Zinc 1197A 0.030 --- ---

4277 0.028 3.30 1.59

4415 0.223 --- ---

4417 0.165 2.41 1.39

4470 1.381 1.69 1.21

4737 0.137 4.45 1.84

4761 0.159 --- ---

4762 0.201 1.60 1.19

4807 0.129 3.00 1.53

4811 0.053 1.32 1.10

4817 0.333 2.02 1.29

4871 0.165 1.71 1.22

4904 0.016 --- —

Oil and Grease (as HEM) 4737 13.6 1.51 1.16

4871 6.1 --- ---

Total Suspended Solids (TSS) 1197A 26.7 --- ---

4011 26.7 --- ---

4079 6.3 --- ---

4277 14.4 1.62 1.19

4384 45.6 2.52 1.42

4415 1.0 --- ---

4417 7.0 3.11 1.60

4438 6.7 --- ----

4470 17.7 2.87 1.50

4737 24.0 2.84 1.49

4761 22.0 --- ---

4762 14.4 1.27 1.09

4807 8.3 2.67 1.47

4811 4.0 --- ---

4817 11.8 3.54 1.67
Table 10-8B (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor

4-Day Variability

Factor

10-46

Total Suspended Solids (TSS)

(continued)

4833 8.4 2.74 1.47

4834 14.6 7.06 2.40

4871 5.8 2.00 1.29

4904 5.7 2.33 1.37

Total Sulfides (as S)c4877 7.1 4.25 1.80

Total Cyanide (d) (d) (d) (d)

Amenable Cyanide (d) (d) (d) (d)

aThe Steel Forming and Finishing Subcategory has mass-based limits, which are being proposed based on the

General Metals Subcategory concentration-based limits. Section 14.0 provides the mass-based limits for the Steel

Forming and Finishing Subcategory and methodology for driving the limits.

bConcentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

cData transfer from Oily Wastes Subcategory.

dSee Table 10-8A, Total and Amenable Cyanide.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-47

Table 10-8C

Episode-Level Long-Term Averages and Variability Factors for

General Metals and Steel Forming and Finishing Subcategories (Option 4)a

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Cadmium 4882 0.007 1.81 1.25

Chromium 4807 0.036 3.95 1.74

4854 0.014 1.69 1.21

4882 0.140 8.61 2.80

Copper 4807 0.074 2.78 1.48

4854 0.084 10.79 3.16

4882 0.026 3.91 1.73

Manganese 4807 0.130 2.21 1.34

Nickel 4807 0.751 2.75 1.47

4854 0.034 6.80 2.33

Silver 4807 0.016 2.94 1.79

Tin 4807 0.018 --- ---

4855 --- 1.58c1.18c

Zinc 4807 0.040 1.87 1.49

4854 0.012 1.84 1.36

4882 0.036 2.70 1.52

Total Suspended Solids (TSS) 4807 22.0 2.10 1.31

4882 4.1 --- ---

Total Organic Carbon (TOC)

(as indicator parameter) d

4737 86.5 1.61 1.19

4761 49.7 --- ---

4762 170.6 1.22 1.07

4806 21.8 3.20 1.57

4807 17.3 2.80 1.48

4817 22.6 1.82 1.24

4833 15.2 5.15 1.95

4834 73.1 1.97 1.28

4871 102.6 1.37 1.12

4904 10.0 --- ---

Leadc4855 0.021 --- ---

Oil and Grease

(as HEM)d

4737 13.6 1.51 1.16

4871 6.136 --- ---

Molybdenumd4806 0.723 2.84 1.49
Table 10-8C (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationb

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

10-48

4904 0.031 1.32 1.11

Total Sulfidee4877 7.1 4.25 1.80

Amenable Cyanide (f) (f) (f) (f)

Total Cyanide (f) (f) (f) (f)

aThe Steel Forming and Finishing Subcategory has mass-based limits, which are being proposed based on the

General Metals Subcategory concentration-based limits. Section 14.0 provides the mass-based limits for the Steel

Forming and Finishing Subcategory and methodology for driving the limits.

bConcentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

cData transfer from Printed Wiring Board Subcategory Option 4.

dData transfer from General Metals Subcategory Option 2.

eData transfer from Oily Wastes Subcategory.

fSee Table 10-8A, Total and Amenable Cyanide.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-49

Table 10-8D

Episode-Level Long-Term Averages and Variability Factors for

Metal Finishing Job Shops Subcategory (Option 2)

Regulated Pollutant Episode

Long-Term

Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Manganese 4278 0.158 1.58 1.18

4279 0.081 8.27 2.71

6178 0.017 --- ---

6187 0.005 --- ---

Tin 4788 1.213 1.49 1.15

Total Organic Carbon (TOC)

(as indicator parameter)

4788 50.4 1.55 1.17

Cadmium 4279 0.137 5.75 2.13

4788 0.021 3.16 1.56

6178 0.035 --- ---

6187 0.055 --- ---

Chromium 4278 0.016 4.45 1.85

4279 0.492 3.25 1.58

4788 0.257 5.12 1.99

4893 0.254 --- ---

6178 0.350 --- ---

6187 0.348 --- ---

Copper 4278 0.128 5.79 2.14

4279 0.105 3.41 1.62

4883 0.368 2.56 1.42

4894 0.358 --- ---

6178 0.438 --- ---

6187 0.302 --- ---

Lead 4788 0.177 1.73 1.22

6178 0.053 --- ---

6187 0.068 --- ---

Silver 4788 0.0181 4.42 1.86

6178 0.3750 --- ---

6187 0.0323 --- ---
Table 10-8D (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term

Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

10-50

Zinc 4278 0.0178 1.82 1.35

4279 1.989 6.54 2.31

4788 0.018 2.76 1.47

4883 0.232 1.85 1.25

4893 0.220 --- ---

4894 0.185 --- ---

6178 0.026 --- ---

6187 0.019 --- ---

Molybdenumb4806 0.723 2.84 1.49

4904 0.031 1.32 1.11

Nickel 4278 0.070 4.36 1.83

4279 0.381 5.68 2.12

4788 0.650 2.09 1.31

4883 0.340 2.71 1.46

4894 0.269 --- ---

Total Organic Carbon (TOC)

(as indicator parameter)

4788 50.4 1.55 1.17

Total Sulfidec4877 7.1 4.25 1.80

Total Cyanide (d) (d) (d) (d)

Amenable Cyanide (d) (d) (d) (d)

a Concentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

b

 Data transfer from General Metals Subcategory Option 2.

c

 Data transfer from Oily Wastes Subcategory.

d See first table under Table 10-8A, Total and Amenable Cyanide.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-51

Table 10-8E

Episode-Level Long-Term Averages and Variability Factors for

Metal Finishing Job Shops (Option 4)

Regulated Pollutant Episode

Long-Term

Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Total Suspended Solidsb4807 22.0 2.10 1.31

4882 4.10 --- ---

Manganeseb4807 0.130 2.21 1.34

Tin 4807 (a) 0.018 --- ---

4855 (c) --- 1.58 1.18

Total Organic Carbon (TOC) (as

indicator parameter)

4788 50.4 1.55 1.17

Cadmium 4882 0.007 1.8 1.25

Chromiumb4807 0.036 3.95 1.74

4854 0.014 1.69 1.21

4882 0.140 8.61 2.80

Copperb4807 0.074 2.78 1.48

4854 0.084 10.79 3.16

4882 0.026 3.91 1.73

Leadd4855 0.021 --- ---

Silverb4807 0.016 2.94 1.79

Zincb4807 0.040 1.87 1.49

4854 0.012 1.84 1.36

4882 0.036 2.70 1.52

Oil and Grease (as HEM)c4737 13.6 1.51 1.16

4871 6.14 --- ---

Molybdenumc4806 0.031 2.84 1.49

4904 0.315 1.32 1.11

Nickelb4807 0.751 2.75 1.47

4854 0.034 6.80 2.33

Total Organic Carbon (TOC) (as

indicator parameter)

4788 50.4 1.55 1.17
Table 10-8E (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term

Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

10-52

Total Sulfide (e) 4877 7.1 4.25 1.80

Total Cyanide (f) (f) (f) (f)

Amenable Cyanide (f) (f) (f) (f)

a Concentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

b

 Data transfer from General Metals Subcategory Option 4.

c

 Data transfer from General Metals Subcategory Option 2.

d Data transfer from Printed Wiring Board Subcategory Option 4.

e Data transfer from Oily Wastes Subcategory.

f

 See Table 10-8A, Total and Amenable Cyanide.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-53

Table 10-8F

Episode-Level Long-Term Averages and Variability Factors for

Nonchromium Anodizing Subcategory (Option 2)

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Total Suspended Solids (TSS) 4856 7.6 1.74 1.22

4869 16.4 6.92 2.38

Aluminum 4856 3.374 1.98 1.29

4869 1.663 4.48 1.85

Manganeseb4762 0.139 1.64 1.20

4807 0.050 2.08 1.31

4871 0.092 1.35 1.11

4904 0.013 2.22 1.35

Nickelb1197A 0.557 --- ---

4277 0.178 1.18 1.06

4438 0.415 --- ---

4470 0.231 1.95 1.28

4761 0.266 --- ---

4762 0.206 2.11 1.32

4807 0.264 2.24 1.35

4811 0.047 1.93 1.36

4817 0.034 2.16 1.33

4833 0.051 --- ---

4834 0.330 2.26 1.35

4847 0.054 3.16 1.56

4871 0.652 1.41 1.13

4904 0.026 ---- ----

6048 0.346 3.15 1.56

Zincb1197A 0.030 --- ---

4277 0.028 3.30 1.59

4415 0.223 --- ---

4417 0.165 2.41 1.39

4470 1.380 1.69 1.21

4737 0.137 4.45 1.84

4761 0.159 --- ---

4762 0.201 1.60 1.19
Table 10-8F (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

10-54

Zinc (continued) 4807 0.129 3.00 1.53

4811 0.053 1.32 1.10

4817 0.333 2.02 1.29

4871 0.165 1.71 1.22

4904 0.016 --- ---

Oil and Grease (as HEM) b 4737 13.6 1.51 1.16

4871 6.13 --- ---

aConcentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

bData transfer from General Metals Subcategory Option2.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-55

Table 10-8G

Episode-Level Long-Term Averages and Variability Factors for

Printed Wiring Boards Subcategory (Option 2)

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Total Cyanide (b) (b) (b) (b)

Amenable Cyanide (b) (b) (b) (b)

Chromiumc1197A 0.638 --- ---

4011 0.871 --- ---

4079 0.970 --- ---

4310 2.272 --- ---

4330 0.067 2.65 1.45

4384 0.585 1.68 1.21

4415 0.0488 --- ---

4417 0.0188 2.47 1.41

4438 0.093 --- ---

4460 1.175 --- —

4470 0.0773 1.73 1.22

4811 0.0085 1.19 1.07

4817 0.0925 6.02 2.19

4833 0.0679 3.37 1.61

4847 0.301 2.73 1.46

4871 0.0101 --- ---

4904 0.0147 1.91 1.27

Copperc4277 0.559 1.73 1.22

4737 0.175 8.73 2.82

4806 0.609 3.58 1.66

4807 1.049 2.98 1.52

4817 0.238 2.50 1.41

4833 0.128 1.63 1.19

4834 0.060 1.81 1.24

4847 0.080 3.05 1.54

4904 0.046 2.03 1.30
Table 10-8G (Continued)

10.0 - Long-Term Averages and Variability Factors

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

10-56

Leadc1197A 1.88 --- ---

4761 0.012 --- ---

4762 0.025 --- ---

4834 0.020 1.55 1.18

4871 0.009 1.88 1.26

Manganese 4866 0.409 3.10 1.55

Nickel 4866 0.111 1.58 1.18

4867 0.049 5.81 2.15

Tin 4866 0.120 3.17 1.56

4867 0.037 4.69 1.90

Zincb1197A 0.030 --- ---

4277 0.028 3.30 1.59

4415 0.223 --- ---

4417 0.165 2.41 1.39

4470 1.381 1.69 1.21

4737 0.137 4.45 1.84

4761 0.159 --- ---

4762 0.201 1.60 1.19

4807 0.129 3.00 1.53

4811 0.053 1.32 1.10

4817 0.333 2.02 1.29

4871 0.165 1.71 1.22

4904 0.016 --- ---

Total Organic Carbon (TOC)

(as indicator parameter)

4866 19.0 2.53 1.42

4867 85.9 1.32 1.11

Total Sulfided4877 7.1 4.25 1.80

aConcentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to 

calculate the LTAs and variability factors.

b See Table 10-8A, Total and Amenable Cyanide.

c

 Data transfer from General Metals Subcategory Option 2.

d

 Data transfer from Oily Wastes Subcategory.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-57

Table 10-8H

Episode-Level Long-Term Averages and Variability Factors for

Printed Wiring Boards Subcategory (Option 4)

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Chromiumb4807 0.036 3.95 1.74

4854 0.014 1.69 1.21

4882 0.140 8.61 2.80

Copper 4855 0.003 --- ---

Lead 4855 0.021 --- ---

Manganeseb4807 0.130 2.21 1.34

Nickelb4807 0.751 2.75 1.47

4854 0.034 6.80 2.33

Oil and Grease (as HEM)b4737 13.6 1.51 1.16

4871 6.13 --- ---

Total Sulfided4877 7.1 4.25 1.80

Tin 4855 0.0547 1.58 1.18

Total Organic Carbon (TOC)

(as indicator parameter)e

4866 19.0 2.53 1.42

4867 85.9 1.32 1.11

Total Suspended Solids (TSS) b4807 22.0 2.10 1.31

4882 4.1 --- ---

Zincb4807 0.040 1.87 1.49

4854 0.012 1.84 1.36

4882 0.036 2.70 1.52

Amenable Cyanide (f) (f) (f) (f)

Total Cyanide (f) (f) (f) (f)

a Concentrations for pollutants not detected in a sample are reported at the detection limit. In these cases, the

detection limit was used to calculate the LTAs and variability factors.

b

 Data transfer from General Metals Subcategory Option 4.

c Data transfer from General Metals Subcategory Option 2.

d

 Data transfer from Oily Wastes Subcategory.

e

 Data transfer from Printed Wiring Board Subcategory Option 2.

f

 See Table 10-8A, Total and Amenable Cyanide.

--- Not calculated due to insufficient data.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-58

Table 10-8I

Episode-Level Long-Term Averages and Variability Factors for

 Oily Waste Subcategory (Option 6)

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Oil and Grease (as HEM) 4851 15.0 1.4 1.13

4877 18.8 1.72 1.22

Total Sulfide 4877 7.1 4.25 1.80

Total Organic Carbon (TOC)

(as indicator parameter)

4851 295 2.04 1.30

4872 188 --- ---

4876 758 3.26 1.58

4877 267 1.45 1.14

Total Suspended Solids (TSS) 4471 45.5 7.73 2.59

4851 41.2 1.47 1.15

4872 11.8 --- ---

4876 15.0 1.86 1.26

4877 19.5 1.80 1.24

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).
10.0 - Long-Term Averages and Variability Factors

10-59

Table 10-8J

Railroad Line Maintenance Subcategory (Option 10)

Regulated Pollutant Episode

Long-Term

Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

BOD 5-Day (Carbonaceous) 6179 5.17 --- ---

4891b--- 6.90 2.39

4892 b--- 6.03 2.19

Total Suspended Solids (TSS) 4891b--- 3.13 1.55

4892b--- 2.34 1.37

6179 10.7 --- ---

Oil and Grease (as HEM) 4892b--- 1.71 1.19

4891b--- 1.82 1.25

6179 6.22 --- ---

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

bData transfer from Shipbuilding Dry Dock Subcategory.

---No samples collected on this day.

CBI - Confidential Business Information.

Table 10-8K

Shipbuilding Dry Dock Subcategory (Option 10)

Regulated Pollutant Episode

Long-Term Average

Concentrationa

(mg/L, ppm)

1-Day Variability

Factor 

4-Day Variability

Factor

Oil and Grease (as HEM) 4891 6.2 1.71 1.19

4892 11.8 1.82 1.25

Total Suspended Solids (TSS) 4805 29.5 --- —

4891 11.6 3.13 1.55

4892 55.0 2.34 1.37

aPollutants not detected in an effluent sample are reported at the detection limit. In these cases, concentrations at

influent to treatment were determined to be at treatable concentrations (see Section 10.2).

---No samples collected on this day.

CBI - Confidential Business Information.
10.0 - Long-Term Averages and Variability Factors

10-60

Table 10-9A

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

General Metals Option 2

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

19 12 12 2.9 1.5 34 18

Oil and Grease

(as HEM)

2 1 9.9 1.6 1.2 15 12

Total Organic Carbon

(TOC) (as indicator

parameter)

10 8 37 2.4 1.4 87 50

Total Organics

Parameter (TOP)

42 12 2.3 3.9 1.8 9.0 4.3

Cadmium 5 2 0.08 2.0 1.3 0.14 0.09

Chromium 17 9 0.10 2.7 1.5 0.25 0.14

Copper 9 9 0.17 3.2 1.6 0.55 0.28

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.65 0.14 0.07

Lead 5 2 0.02 1.8 1.3 0.04 0.03

Manganese 4 4 0.07 1.9 1.3 0.13 0.09

Molybdenum 2 2 0.38 2.1 1.3 0.79 0.49

Nickel 15 10 0.24 2.2 1.4 0.50 0.31

Silver 4 3 0.05 4.7 2.0 0.22 0.09

Total Sulfide 1 1 7.1 4.3 1.80 31 13

Tin 2 2 0.44 3.0 1.6 1.4 0.67

Zinc 13 9 0.16 2.4 1.4 0.38 0.22
10.0 - Long-Term Averages and Variability Factors

10-61

Table 10-9B

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

General Metals Subcategory (Option 4)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

2 1 13 2.1 1.4 28 18

Oil and Grease (as

HEM)

2 1 9.9 1.6 1.2 15 12

Total Organic Carbon

(TOC) (as indicator

parameter)

10 8 37 2.4 1.4 87 50

Total Organics

Parameter

42 12 2.3 3.9 1.8 9.0 4.3

Cadmium 1 1 0.01 1.8 1.3 0.02 0.01

Chromium 3 3 0.04 4.8 2.0 0.17 0.07

Copper 3 3 0.08 5.9 2.2 0.44 0.16

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.7 0.14 0.07

Lead 1 --- 0.03 1.6 1.2 0.04 0.03

Manganese 1 1 0.13 2.3 1.4 0.29 0.18

Molybdenum 2 2 0.38 2.1 1.3 0.79 0.49

Nickel 2 2 0.40 4.7 1.9 1.88 0.75

Silver 1 1 0.02 3.0 1.8 0.05 0.03

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Tin 1 1 0.02 1.6 1.2 0.03 0.03

Zinc 3 3 0.04 2.2 1.5 0.08 0.06
10.0 - Long-Term Averages and Variability Factors

10-62

Table 10-9C

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Metal Finishing Job Shops Subcategory (Option 2)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA (mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids 

(TSS)

NA NA NA NA NA 60a31a

Oil and Grease

(as HEM) 

NA NA NA NA NA 52a26a

Total Organic Carbon

(as indicator parameter)

1 1 51 1.6 1.2 78 59

Total Organics

Parameter

42 12 2.3 3.9 1.8 9.0 4.3

Cadmium 4 2 0.05 4.5 1.9 0.21 0.09

Chromium 6 3 0.31 4.3 1.8 1.3 0.55

Copper 6 3 0.34 4.0 1.8 1.3 0.58

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.7 0.14 0.07

Lead 3 1 0.07 1.8 1.3 0.12 0.09

Manganese 4 2 0.05 5.0 2.0 0.25 0.10

Molybdenum 2 2 0.38 2.1 1.3 0.79 0.49

Nickel 5 4 0.39 3.7 1.7 1.5 0.64

Silver 3 1 0.04 4.5 1.9 0.15 0.06

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Tin 1 1 1.3 1.5 1.2 1.8 1.4

Zinc 8 4 0.11 3.3 1.6 0.35 0.17

a

 For existing sources, limits are transferred from 40 CFR 433 (Metal Finishing).

NA - Not applicable.
10.0 - Long-Term Averages and Variability Factors

10-63

Table 10-9D

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Metal Finishing Job Shops Subcategory (Option 4)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

2 1 13 2.1 1.4 28 18

Oil and Grease (as

HEM)

2 1 9.9 1.6 1.2 15 12

Total Organic Carbon

(TOC) (as indicator

parameter)

1 1 51 1.6 1.2 78 59

Total Organics

Parameter

42 12 2.3 3.9 1.8 9.0 4.3

Cadmium 1 1 0.01 1.8 1.3 0.02 0.01

Chromium 3 3 0.04 4.8 2.0 0.17 0.07

Copper 3 3 0.08 5.9 2.2 0.44 0.16

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.7 0.14 0.07

Lead 1 --- 0.03 1.6 1.2 0.04 0.03

Manganese 1 1 0.13 2.3 1.4 0.29 0.18

Molybdenum 2 2 0.38 2.1 1.3 0.79 0.49

Nickel 2 2 0.40 4.7 1.9 1.88 0.75

Silver 1 1 0.02 3.0 1.8 0.05 0.03

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Tin 1 1 0.02 1.6 1.2 0.03 0.03

Zinc 3 3 0.04 2.2 1.5 0.08 0.06
10.0 - Long-Term Averages and Variability Factors

10-64

Table 10-9E

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Non-Chromium Anodizing Subcategory (Option 2)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

2 2 12 4.4 1.8 52 a22 a

Oil and Grease (as

HEM)

2 1 9.9 1.6 12 15a12 a

Aluminum 2 2 2.6 3.3 1.6 8.2 4.0

Manganese 4 4 0.07 1.9 1.3 0.13 0.09

Nickel 15 10 0.24 2.2 1.4 0.50 0.31

Zinc 13 9 0.16 2.4 1.4 0.38 0.22

a

 As shown in Section 14.0 EPA transferred limits for TSS and oil and grease for existing sources from 40 CFR 433 (Metal Finishing). 

The limits for TSS and oil and grease shown in this table are being proposed for new sources.
10.0 - Long-Term Averages and Variability Factors

10-65

Table 10-9F

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Printed Wiring Boards (Option 2)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

NA NA NA NA NA 60 a31a

Oil and Grease (as

HEM)

NA NA NA NA NA 52 a26a

Total Organic Carbon

(TOC) (as indicator

parameter)

2 2 53 2.0 1.3 101 67

Total Organics

Parameter

42 12 2.3 3.9 1.8 9.0 4.3

Chromium 17 9 0.10 2.7 1.5 0.25 0.14

Copper 9 9 0.18 3.2 1.6 0.55 0.28

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.7 0.14 0.07

Lead 5 2 0.02 1.8 1.3 0.04 0.03

Manganese 1 1 0.41 3.1 1.6 1.3 0.64

Nickel 2 2 0.08 3.7 1.7 0.30 0.14

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Tin 2 2 0.08 4.0 1.8 0.31 0.14

Zinc 13 9 0.16 2.4 1.4 0.38 0.22

a

 For existing sources, limits are transfered from 40 CFR 433 (Metal Finishing).
10.0 - Long-Term Averages and Variability Factors

10-66

Table 10-9G

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Printed Wiring Boards (Option 4)

Regulated

Parameter

Number

of Sites

(LTA)

Number

of Sites

(VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variabilit

y Factor

4-Day

Variability

Factor

Maximum

Daily1

Maximum

Monthly

Avg.1

Total Suspended Solids (TSS) 2 1 13 2.1 1.4 28 18

Oil and Grease (as HEM) 2 1 9.9 1.6 1.2 15 12

Total Organic Carbon (TOC)

(as indicator parameter)

2 2 53 2.0 1.3 101 67

Total Organics Parameter

(TOP)

42 12 2.3 3.9 1.8 9.0 4.3

Chromium 3 3 0.4 4.8 2.0 0.17 0.07

Copper 1 0.01 1.6 1.2 0.01 0.01

Total Cyanide 13 9 0.09 2.4 1.4 0.21 0.13

Amenable Cyanide 8 5 0.04 3.4 1.7 0.14 0.07

Lead 1 0.03 1.6 1.2 0.04 0.03

Manganese 1 1 0.13 2.3 1.4 0.29 0.18

Nickel 2 2 0.40 4.7 1.9 1.88 0.75

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Tin 1 1 0.06 1.6 1.2 0.09 0.07

Zinc 3 3 0.04 2.2 1.5 0.08 0.06
10.0 - Long-Term Averages and Variability Factors

10-67

Table 10-9H

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Oily Wastes Subcategory (Option 6)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

5 4 20 3.3 1.6 63 31

Oil and Grease

(as HEM)

2 2 17 1.6 1.2 27 20

Total Organic Carbon

(TOC) (as indicator

parameter)

4 3 282 2.3 1.4 633 378

Total Organics

Parameter 

42 12 2.3 3.9 1.8 9.0 4.3

Total Sulfide 1 1 7.1 4.3 1.8 31 13

Table 10-9I

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Railroad Line Maintenance Subcategory (Option 10)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA

(mg/L,

ppm)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

5-Day Biochemical

Oxygen Demand

(BOD5)

1 2 5.2 6.5 2.3 34 12

Total Suspended Solids

(TSS)

1 2 11 2.8 1.5 30 16

Oil and Grease

(as HEM)

1 2 6.3 1.8 1.3 11 7.6
10.0 - Long-Term Averages and Variability Factors

10-68

Table 10-9J

Pollutant-Level Long-term Averages, Variability Factors and Limitations for

Shipbuilding Dry Docks Subcategory (Option 10)

Regulated

Parameter

Number of

Sites (LTA)

Number of

Sites (VF)

Median

LTA (mg/,

ppml)

1-Day

Variability

Factor

4-Day

Variability

Factor

Maximum

Daily

(mg/L,

ppm)

Maximum

Monthly

Avg.

(mg/L,

ppm)

Total Suspended Solids

(TSS)

3 2 30 2.8 1.5 81 44

Oil and Grease

(as HEM)

2 2 9.0 1.8 1.3 16 11

Source: MP&M LTA Database.
11.0 - Costs of Technology Bases for Regulations

11-1

11.0 COSTS OF TECHNOLOGY BASES FOR REGULATIONS

This section describes the methodology used to estimate the costs for

implementing each of the technology options under consideration for the MP&M Point Source

Category. Section 8.0 describes the technologies considered and Section 9.0 describes the

combination of these technologies into options for in-process source reduction and recycling and

end-of-pipe wastewater treatment. The cost estimates, together with the pollutant reduction

estimates described in Section 12.0, provide a basis for evaluating the options discussed in

Section 9.0. The cost estimates also provide a basis for determining the economic impact of the

regulation on the industry as discussed in the report titled Economic, Environmental, & Benefit

Analysis of the Proposed Metal Products & Machinery Rule (EEBA) (1). The EEBA is included

in the public record for this rulemaking.

EPA used the following approach to estimate compliance costs for the MP&M

industry.

C Select probability samples of MP&M industry sites to receive industry

surveys (see Section 3.0). EPA estimated costs of compliance for each

survey site (i.e., model site) based on factors such as unit operations,

wastewater characteristics, treatment currently in place, etc. (see Section

11.2).

C Analyze field sampling data for unit operations to determine the pollutant

concentrations of untreated wastewater in the industry (see Section 12.0).

C Identify candidate in-process source reduction and recycling and end-ofpipe wastewater treatment technologies, and group them into technology

options. The technology options serve as the basis of compliance cost and

pollutant loading calculations (see Section 9.0).

C Analyze field sampling data for wastewater treatment systems to

determine pollutant removal performance of the selected technologies (see

Section 10.0).

C Develop cost equations for capital and operating and maintenance (O&M)

costs for each of the technologies (see Section 11.4).

C Evaluate the current (baseline) treatment technology in place at each

model site (i.e., survey site) and estimate baseline pollutant loadings and

operating and maintenance costs using a computerized design and cost

model (the MP&M Design and Cost Model). 
11.0 - Costs of Technology Bases for Regulations

11-2

C Use the MP&M Design and Cost Model to estimate compliance costs

(presented in Section 11.2) and pollutant loadings (presented in Section

12.0) for each model site for each option.

C Use sample weights based on survey sample frame to estimate, for

national population, industry compliance costs and pollutant loadings.

C Estimate total annualized costs, cost effectiveness, and the economic

impact to the industry (presented in the EEBA) using output from the

MP&M Design and Cost Model.

EPA estimated industry-wide costs for 10 technology options by computing

compliance costs for technology trains at 890 model sites. The Agency used these model sites to

estimate costs for 63,000 water-discharging MP&M sites using statistically calculated industry

weighting factors (i.e., sample weights). Many of these 63,000 MP&M sites are indirect

dischargers with flows under the proposed low flow exclusions and are not included in the final

cost estimates of the proposed rule. Section 11.1 summarizes the results of the costing effort. 

Section 11.2 presents the methodology used to select and develop model sites. Section 11.3

presents the methodology for estimating costs, including descriptions of the components that

define capital and annual costs, sources of cost data, standardization of cost data, an overview of

the MP&M Design and Cost Model, and general assumptions used for costing. Section 11.4

describes the design and costing methodology for each in-process and end-of-pipe technology

used in the options. Tables are presented in the text and figures are located at the end of this

section. 

11.1 Summary of Costs

EPA identified several in-process and end-of-pipe technologies applicable to

MP&M wastewater (Section 8.0), and combined these into technology options (Section 9.0). 

Overall, EPA considered 10 technology options, although several options are only applicable to

certain MP&M subcategories. Based on the technologies included in each option and the

specific wastewater generated at the MP&M model sites (based on questionnaire responses),

EPA used the MP&M Design and Cost Model to estimate compliance costs for each model site

for each option. 

Table 11-1 presents annualized costs for both direct and indirect dischargers by

subcategory for all proposed options for existing sources (Options 2, 6, 10). Costs for options

that EPA did not propose are not presented in this section but are discussed in Section 14. EPA

notes that costs for options 1, 3, 5, 7, and 9 (those options without pollution prevention (P2) cost

more and remove fewer pollutants than the comparable technology with pollution prevention (see

Section 14). 

Cost estimates presented in Table 11-1 will not equate with those presented in the

EEBA because those costs include other system annual costs (e.g., taxes and amortization). In
11.0 - Costs of Technology Bases for Regulations

11-3

addition, EEBA cost estimates are presented in 1999 dollars (where costs in this section are in

1996 dollars), and the EEBA cost estimates do not include costs for facilities that are projected to

close in the baseline based on a site’s responses to EPA’s economic portion of industry

questionnaires, (i.e., based on a site’s responses to EPA’s economic portion of industry

questionnaires, EPA estimates these facilities will close, regardless of the MP&M effluent

guidelines, prior to the implementation of the MP&M guidelines).
11.0 - Costs of Technology Bases for Regulations

11-4

Table 11-1

MP&M Total Estimated Annualized Costs 

at the Proposed Options for Existing Sources

Subcategory

Proposed

Option

Number

Direct Dischargers Indirect Dischargers

Number of

Sites

Total Annualized Cost

(millions of 1996 dollars)

Number of

Sites

Flow

Cutoff

Total Annualized Cost

(millions of 1996

dollars)

General Metals 2 3,794 230 3,055 1 MGY 1,570

Metal Finishing Job Shop 2 15 1.3 1,514 None 178

Non-Chromium Anodizing 2 NA NA Not

Proposed

None Not Proposed

Printed Wiring Board 2 11 2.5 621 None 147

Steel Forming and Finishing 2 43 29.3 110 None 24

Oily Waste 6 911 11.2 226 2 MGY 10

Railroad Line Maintenance 10 34 1.18 Not

Proposed

None Not Proposed

Shipbuilding Dry Dock 10 6 2.15 Not

Proposed

None Not Proposed

All Categories: Annualized Costs 2/6/10 4,814 280 5,530 -------- 1,930

Source: MP&M Design and Cost Model.

NA - Not applicable, EPA’s data collection efforts have not identified any direct discharging non-chromium anodizing facilities.

Note: Cost estimates presented in this table will not equate with those presented in the EEBA. The cost estimates in the EEBA are presented in 1999 dollars and

do not include costs for facilities that are projected to close in the baseline.
11.0 - Costs of Technology Bases for Regulations

11-5

11.2 Model Site Development

The Agency used a model site approach to estimate costs for the 63,000 waterdischarging sites in the MP&M Point Source Category based on cost estimates for a statistically

sampled subset of sites. To account for the variability in processes and treatment systems in

place within the MP&M Point Source Category, EPA developed a model site from each survey

(see Section 3.0) that met the criteria described below.

11.2.1 Site Selection

EPA selected model sites from sites receiving industry surveys. Section 3.1

discuss data collection and survey activities. The Agency selected a site as a model site if it met

the following criteria:

C The site discharged wastewater (treated or untreated) to either a surface

water or publicly owned treatment works (POTW); and

C The site supplied sufficient technical data required to estimate compliance

costs and pollutant loadings reductions associated with the technology

options. 

Based on these criteria, EPA selected 890 survey respondents for model site

development. The Agency used statistically-determined survey weights to estimate the national

MP&M industry population of 63,000 sites. Development of the survey weights and the

statistical methodology used to characterize the industry are documented in the public record for

this rulemaking.

11.2.2 Wastewater Stream Parameters

Based on the information provided by the sites in their survey responses, followup letters, and phone calls, EPA classified each process wastewater stream at each site by the

type of unit operation (e.g., machining, electroplating, acid treatment) generating the wastewater. 

For each operation, EPA used survey data to obtain the following parameters: 

C Wastewater discharge flow rate. For each process wastewater stream,

sites reported the total wastewater discharge flow rate from the unit

operation. For sites that did not report wastewater discharge data, EPA

statistically imputed wastewater flow rates using other data provided in the

site’s survey or by using data for similar unit operations reported in other

surveys. The approach for this modeling is documented in the public

record for this rulemaking.

C Production rate. Sites reported production rates in either surface area

processed, mass of metal removed, or air flow rate. The production
11.0 - Costs of Technology Bases for Regulations

11-6

parameter used depended on the unit operation. EPA used surface area for

surface finishing or cleaning operations, mass of metal removed for metal

removal operations such as machining and grinding, and air flow rate for

air pollution control operations. For sites that did not report production

data, EPA statistically imputed production rates using other data provided

in the site’s survey or by using data for similar unit operations reported in

other surveys. The approach for this modeling is documented in the public

record for this rulemaking.

C Operating schedule. EPA used survey responses to estimate the

operating rate (hours per day (hpd) and days per year (dpy)) of each unit

operation when supplied by sites. For blank responses, EPA used the

following:

– The maximum hpd and dpy reported by the site for other unit

operations;

– The survey response for wastewater treatment system operating

schedule, if all hpd and dpy responses at the unit operation level

were blank; or

– 8 hpd and 250 dpy, if all unit operation operating rate survey

responses were blank and no wastewater treatment system

operating schedule was provided. 

C Discharge destination. EPA used survey responses to determine whether

each unit operation discharged process wastewater, and if so, whether the

wastewater was discharged to a surface water or POTW. EPA also

determined from the survey responses whether the wastewater was treated

on site prior to discharge. The MP&M Design and Cost Model did not

assign costs to wastewater that sites reported to be contract hauled off site,

deep-well injected, discharged to septic systems, not discharged, or reused

on site. For sites that did not report a discharge destination for some or all

operations, EPA modeled the destination based on other technical

information provided in the survey (e.g., types of discharge permits,

discharge destination of other unit operations, process flow diagrams).

11.2.3 Pollutant Concentrations

The Agency estimated the concentration of each pollutant in each model site’s

process wastewater stream using field sampling data for raw wastewater discharged from MP&M

 unit operations. Section 3.0 discusses the field sampling program. EPA used these data with

survey flow and production data to calculate the pollutant loadings. Section 12.0 discusses these

calculations in more detail as well as the calculations for estimating site specific pollutant
11.0 - Costs of Technology Bases for Regulations

11-7

removals. In addition, Section 10 provides information about the data used to estimate pollutant

concentrations in the effluent stream following treatment for the various technology options.

11.2.4 Technology in Place

The term “technology in place” refers to those technologies that the Agency

considered to be installed and operating at a model site at the time the facility completed the

detailed industry survey. EPA accounted for technology in place in the costing and pollutant

removal efforts to ensure that EPA accurately assessed the treatment costs associated with a

facility upgrading its treatment system (including P2) to meet the MP&M standards and the

current level of pollutant being discharged by facilities with treatment in place. 

Although both the 1989 and 1996 MP&M Detailed Surveys requested detailed

information on end-of-pipe treatment-in-place, only the 1996 MP&M Detailed Survey requested

information about a facility’s in-process pollution prevention technologies. For the 1996 MP&M

Detailed Surveys, EPA assigned pollution prevention technology in place based on information

contained in the responses to this survey. For other model sites, the Agency assumed in-process

pollution prevention technologies were in place for a particular unit operation if the model site’s

process wastewater stream had a production-normalized flow rate (PNF, volume of wastewater

per unit of production) below the median PNF calculated from the 1996 MP&M Detailed Survey

for processes incorporating that pollution prevention technology. For example, if a 1989 survey

site reported a machining wastewater stream with a PNF below the median PNF for

centrifugation and pasteurization of machining coolant, then the Agency assumed that the model

site had a machining coolant regeneration system in place. The median PNFs for each

technology are listed in Section 15 and documented in the public record for this rulemaking.

EPA used a similar method to give credit to sites using efficient rinse schemes. 

EPA used the following parameters to compute flow reductions and costs for incorporating

pollution prevention in rinse lines by converting the rinse to a two-stage countercurrent rinse. 

Additional information on the in-process pollution prevention and rinse flow reduction

methodology can be found in the public record for this rulemaking.

C Tank volume. Although tank volume is a design parameter for

countercurrent cascade rinsing, the Agency did not request this

information in the surveys. EPA used a linear relationship between tank

size and annual discharge flow rate to estimate the volume of the existing

tank and for the estimated volumes of additional rinse tank(s) that may

need to be installed in order to incorporate countercurrent cascade rinsing.

C Rinse code. EPA uses the rinse code parameter to compute a flow

reduction for conversion of the model site’s current rinse scheme to a twostage countercurrent rinse. The 1996 MP&M Detailed Surveys contained

specific information about each rinse. EPA used this information to

determine the median PNF for each of the five general rinse categories. 
11.0 - Costs of Technology Bases for Regulations

11-8

As documented in the public record for this rulemaking, EPA assigned

rinses from all surveys one of the five general rinse codes based on

specific rinse code information contained in the survey or the PNF for the

rinse stream. The Agency used these codes to estimate rinse flow

reduction costs for model sites that do not currently use countercurrent

rinsing.

C Equipment code. EPA determined the type of rinse equipment in place

and assigned an equipment code based on the detailed rinse information in

the 1996 surveys. For surveys that did not contain detailed information,

EPA used the model site’s PNF to assign an equipment code. 

EPA reviewed survey data for each model site to assess the types of preliminary

and end-of-pipe technologies in place at each site (e.g., chemical reduction of chromium, sludge

pressure filtration). EPA identified end-of-pipe technologies on site that, based on technical

considerations, it considered equivalent to technologies included in the technology options. For

example, the Agency considered vacuum filtration to be equivalent to pressure filtration for

sludge dewatering. EPA also identified technologies that it did not consider equivalent, and for

which it assigned no credit for technology in place. For example, EPA did not consider oil/water

separation equivalent to ultrafiltration in the technology options; however, it did consider

ultrafiltration to be treatment in place for treatment options specifying oil/water separation or

dissolved air flotation. EPA assumed that sites specifying only chemical precipitation also had a

clarifier. In addition, the Agency assumed sites with treatment systems in place have the

associated chemical feed systems in place. Site-specific assumptions regarding treatment

technologies in place at model sites are included in the administrative record for this rulemaking

(Technology in Place Documentation for MP&M Phase I/II Survey Respondents, DCN

16323/15799).

EPA used survey data for the following parameters to assess the capacity of the

end-of-pipe technologies in place at the model sites:

C Operating schedule. EPA used survey responses to estimate the

operating schedule (hours per day (hpd) and days per year (dpy)) for each

treatment unit when supplied by sites. For blank responses, EPA

determined the schedule using the following:

– The maximum hpd and dpy reported for the unit operations, if all

hpd and dpy responses for the treatment unit were blank; 

– The maximum hpd and dpy reported by the site for other unit

operations associated with other treatment units; or 

– 8 hpd and 250 dpy, if all hpd and dpy survey responses were blank

for unit operations and treatment units.
11.0 - Costs of Technology Bases for Regulations

11-9

. 

C Wastewater streams treated. EPA determined the unit operation

wastewater streams treated by each end-of-pipe technology in place using

the following:

– Survey process flow diagrams or responses to survey questions

regarding the destination of individual process wastewater streams,

and

– The logic used by the model for assigning streams to technologies 

if information provided in the survey was insufficient, (e.g., EPA

assumed that sites treated cyanide-bearing streams using cyanide

destruction if the site currently had it in place). This logic is

described in Section 11.3.

EPA used the baseline operating schedule and wastewater streams treated by the

technology to define the maximum operating capacity for each technology. The Agency

determined design capacity flow from the larger of the survey response flow (when available) or

the model design capacity flow as derived from the baseline flow. EPA assumed that each model

site with end-of-pipe treatment technologies in place operated their system at 78 percent of full

capacity (at baseline). The Agency estimated the operating capacity based on an average of

survey data (documentation is included in the public record for this rulemaking). Because a site

may need to increase its wastewater treatment capacity as a result of the process changes

associated with some of EPA’s technology options, Section 11.3.4 presents assumptions

regarding how the model accounted for baseline end-of-pipe technologies with insufficient

capacity.

11.3 Methodology for Estimating Costs

This section discusses the methodology for estimating costs, including the

components of cost (Section 11.3.1), the sources and standardization of cost data (Section

11.3.2), the MP&M Design and Cost Model (Section 11.3.3), and the general assumptions made

during the costing effort (Section 11.3.4).

11.3.1 Components of Cost

The components of the capital and annual costs and the terminology used in

developing these costs are presented below. 

Capital Costs

The capital costs consist of two major components: direct capital costs and

indirect capital costs. The direct capital costs include:
11.0 - Costs of Technology Bases for Regulations

11-10

C Purchased equipment cost, including ancillary equipment (e.g., piping,

valves, controllers);

C Delivery cost (based on the equipment weight and a shipping distance of

500 miles); and 

C Installation cost (including labor and site work).

EPA derived the direct components of the total capital cost separately for each

treatment unit or pollution prevention technology. When possible, EPA obtained costs for

various sizes of preassembled, skid-mounted treatment units from equipment vendors. If costs

for preassembled, skid-mounted treatment units were not available, EPA obtained catalog prices

for individual system components (e.g., pumps, tanks, feed systems) and summed these prices to

estimate the cost for the treatment unit.

Indirect capital costs consist of secondary containment, engineering, contingency,

and contractor fees. When combined with the direct capital costs, these form the total capital

investment. EPA estimates the indirect costs as percentages of the total direct capital cost, as

shown in Table 11-2.

Table 11-2

Components of Total Capital Investment

Item

Number

Item Cost

1 Equipment capital costs including required accessories,

installation, delivery, electrical and instrumentation, yard

piping, enclosure, pumping, and retrofit allowance

Direct capital cost

2 Engineering/administrative and legal 10% of item 1

3 Secondary containment/land costs 10% of item 1

4 Total plant cost Sum of items 1 through 3

5 Contingency 15% of item 4

6 Contractor’s fee 5% of item 4

7 Total capital investment Sum of items 4 through 6

Source: MP&M Design and Cost Model. 
11.0 - Costs of Technology Bases for Regulations

11-11

Annual Costs

As with capital costs, the annual costs have both a direct and an indirect

component. The equations used to calculate individual equipment direct annual costs include the

following.

C Raw material costs. Chemicals and other materials used in the treatment

processes (e.g., calcium hydroxide, sulfuric acid, sodium hypochlorite);

C Operating labor and material costs. The labor and materials directly

associated with operation of the process equipment;

C Maintenance labor and material costs. The labor and materials required

for repair and routine maintenance of the equipment; and

C Energy costs. Calculated based on total energy requirements (in kW-hrs).

Indirect annual costs include monitoring, taxes, insurance, and amortization. 

Monitoring is the periodic analysis of wastewater effluent samples to ensure that discharge

limitations are being met. Section 11.3.2 discusses assumptions regarding monitoring frequency.

The EEBA discusses taxes and amortization.

Total Annualized Costs

EPA calculated total annualized costs (TAC) from the capital and annual costs

generated by the MP&M Design and Cost Model. The Agency assumed a 7 percent discount rate

over an estimated 15-year equipment life.

11.3.2 Sources and Standardization of Cost Data

EPA obtained capital and annual cost data for the technologies that constitute

EPA’s technology options (see Section 9) from equipment vendors, literature, and from existing

MP&M sites. The Agency used specific data from the 1989 and 1996 MP&M Detailed Surveys

whenever possible; however, the required types of data were often either not collected or not

supplied by the sites. The major sources of equipment cost data were equipment vendors, while

the literature provided most of the annual cost information. 

Capital and annual cost data were standardized to 1996 dollars (the most current

year in which EPA collected survey data) based on the following:

C Capital Equipment. EPA adjusted capital costs obtained in 1998 dollars

to 1996 dollars using RSMeans Building Construction Historical Cost

Indexes (see Table 11-3). The values of this index for 1996 and 1998

were 110.2 and 114.4, respectively. EPA decreased capital equipment
11.0 - Costs of Technology Bases for Regulations

11-12

costs by 3.7 percent (110.2/114.4 × 100) to account for inflationary

changes between 1996 and 1998. 

C Chemicals. EPA used the Chemical Marketing Reporter from December,

1997 to obtain chemical prices. 

C Water and Sewer Costs. EPA based water and sewer use prices on data

collected through an EPA Internet search of various public utilities located

throughout the United States for years ranging from 1996 to 1999. EPA

adjusted rates to a 1996 basis using the RSMeans Building Construction

Historical Cost Indexes. The average water and sewer use charges were

$2.03 per 1,000 gallons and $2.25 per 1,000 gallons, respectively. 

C Energy. EPA determined electricity prices from the U.S. Department of

Energy’s Energy Information Administration. The average electrical cost

to industrial users from 1994 to 1996 was $0.047 per kW-hr. 

C Labor. EPA used labor rate of $29.67 per hour to convert the labor

requirements of each technology into annual costs. The Agency obtained

the base labor rate from the Monthly Labor Review, which is published by

the U.S. Bureau of Labor Statistics of the U.S. Department of Labor. 

Excluding the maximum and minimum values, EPA used the largest

remaining monthly value for 1997 for production labor in the fabricated

metals industry, $12.90 per hour, as a conservative estimate. The Agency

added 15 percent of the base labor rate for supervision and 100 percent for

overhead to obtain the labor rate of $29.67 per hour.

C Monitoring. EPA did not include the annual cost of wastewater analyses

because it assumed that no incremental monitoring costs would be

incurred at the technology options above a site’s current baseline

monitoring.

C Contract Hauling. EPA based contract-hauling costs on averaged data

from the 1996 MP&M Detailed and Screener Surveys as discussed in

Section 11.4.4. The Agency estimated costs for contract hauling of RCRA

hazardous metal hydroxide sludge from Pollution Prevention and Control

Technology for Plating Operations (3). The contract hauling costs for

various waste types are provided in Table 11-4. 
11.0 - Costs of Technology Bases for Regulations

11-13

Table 11-3

RSMeans Building Construction Historical Cost Indexes

Year Index

1989 92.1

1990 94.3

1991 96.8

1992 99.4

1993 101.7

1994 104.4

1995 107.6

1996 110.2

1997 112.8

1998 114.4

Reference: Historical Cost Indexes, RSMeans Building Construction Cost Data, 56th

Annual Edition, 1998, page 594. (2)

Table 11-4

Contract-Hauling Costs for Various Waste Types

Waste Type Cost ($/gallon)

RCRA hazardous non-hazardous paint sludge 3.70

RCRA hazardous metal hydroxide sludge (3) 1.95

RCRA non-hazardous oil 0.86

Solvent (paint and paint stripping waste) 2.85

Oily wastewater 1.33

General metal-bearing wastewater 2.00

Cyanide-bearing wastewater 5.64

Hexavalent chromium-bearing wastewater 3.51

Chelated metal-bearing wastewater 1.40

Source: 1996 MP&M Detailed and Screener Surveys.

11.3.3 MP&M Design and Cost Model

The Agency developed cost modules for the in-process source reduction and

recycling and end-of-pipe wastewater treatment technologies and practices included in the

technology options. Table 11-5 presents these technologies and practices. Specific details

regarding the design and costing of each technology and practice are described in Section 11.4. 
11.0 - Costs of Technology Bases for Regulations

11-14

Figure 11-1 shows the relationship between in-process and end-of-pipe technologies and

practices.

Table 11-5

 Wastewater Treatment Technologies and Source Reduction

 and Recycling Practices for Which EPA Developed Cost Modules 

In-Process Technologies and Practices End-Of-Pipe Technologies and Practices

Countercurrent cascade rinsing

Centrifugation and pasteurization of machining

coolants

Centrifugation of painting water curtains

Chemical reduction of hexavalent chromium

Cyanide destruction

Chemical reduction of chelated metals

Chemical emulsion breaking

Gravity oil/water separation

Dissolved air flotation

Gravity oil emulsion breaking (baseline only, see 

 Section 11.3.4)

Ultrafiltration for oil removal

Contract hauling of solvent degreasing wastewaters

Chemical precipitation

Gravity clarification for solids removal

Microfiltration for solids removal

Sludge thickening

Sludge pressure filtration

Multimedia filter (baseline only, see Section 11.3.4)

Source: MP&M surveys, MP&M site visits, technical literature. 

EPA developed a computerized design and cost model to estimate compliance

costs and pollutant loadings for the MP&M technology options, taking into account each site’s

treatment in place. The model was programmed with modules, which allowed the user to specify

various combinations of technologies and pollution prevention practices to be costed as required

by the technology options and as required by each model site’s wastewater stream characteristics. 

A baseline run estimated current annual costs (operating and maintenance) for each site and

assessed the current capacity of treatment equipment in place using the site’s specified treatment

equipment and the estimated wastewater flow requiring a particular type of treatment. For

estimating costs and pollutant loadings for each of the technology options, the model costed each

site by assigning a particular type of treatment unit to each wastestream generated by the site 

(see Table 11-6). EPA took into account current treatment in place and existing annual costs (for

chemical addition, etc.) from baseline when estimating costs associated with the proposed rule. 

EPA designated specifically which unit operations would feed each treatment unit (or pollution

prevention technology) based on the properties of that unit operation’s discharge stream (e.g.,

cyanide bearing wastewater feeds cyanide destruction, flowing rinses feed countercurrent cascade

rinsing). 

In the context of the MP&M cost program, “model” refers to the overall computer

program and “module” refers to a computer subroutine that generates costs and pollutant
11.0 - Costs of Technology Bases for Regulations

11-15

loadings for a specific in-process or end-of-pipe technology or practice (e.g., chemical

precipitation and sedimentation, contract hauling). EPA adapted some modules from cost

modules used for previous EPA rulemaking efforts for the metals industry, while it developed

others specifically for this rulemaking effort. 

Table 11-6

List of Unit Operations Feeding Each Treatment Unit

or In-Process Technology 

Treatment Unit / P2 Equipment Unit Operations Feeding Unita

Countercurrent cascade rinsing Acid treatment with chromium rinse

Acid treatment without chromium rinse

Alkaline cleaning for oil removal rinse

Alkaline treatment with cyanide rinse

Alkaline treatment without cyanide rinse

Anodizing with chromium rinse

Anodizing without chromium rinse

Aqueous degreasing rinse

Barrel finishing rinse

Chemical conversion coating without chromium rinse

Chemical milling rinse

Chromate conversion coating rinse

Corrosion preventive coating rinse

Electrochemical machining rinse

Electroless plating rinse

Electrolytic cleaning rinse

Electroplating with chromium rinse

Electroplating with cyanide rinse

Electroplating without chromium or cyanide rinse

Electropolishing rinse

Heat treating rinse

Salt bath descaling rinse

Solvent degreasing rinse

Stripping (paint) rinse

Stripping (metallic coating) rinse

Testing rinse

Washing finished products rinse

Carbon black deposition rinse
Table 11-6 (Continued)

11.0 - Costs of Technology Bases for Regulations

Treatment Unit / P2 Equipment Unit Operations Feeding Unita

11-16

Galvanizing/hot dip coating rinse

Mechanical plating rinse

Laundering rinse

Countercurrent cascade rinsing (cont.) Cyanide rinsing

Ultrasonic machining rinse

Phosphor deposition rinse

Centrifiguration and pasteurization of

machining coolant

Multiple unit operation rinse

Grinding

Machining

Centrifugation of painting water

curtains

Painting - spray or brush

Painting - immersion

Chemical emulsion breaking and

Oil/water separation 

OR

Dissolved air flotation 

OR 

Ultrafiltration system for oil removal

Alkaline cleaning for oil removal and rinse

Aqueous degreasing

Assembly/disassembly

Electrical discharge machining rinse

Electrolytic cleaning

Electroplating without chromium or cyanide

Floor cleaning and rinse

Grinding rinse

Heat treating

Impact deformation and rinse

Machining and rinse

Painting - spray or brush

Painting - immersion

Pressure deformation

Stripping (paint)

Stripping (metallic coating) rinse

Testing

Thermal cutting rinse

Washing finished products and rinse

Bilge water

Mechanical plating

Photo image developing

Photo imaging

Steam cleaning

Vacuum impregnation
Table 11-6 (Continued)

11.0 - Costs of Technology Bases for Regulations

Treatment Unit / P2 Equipment Unit Operations Feeding Unita

11-17

Laundering

Calibration

Centrifugation and pasteurization of machining coolant

Chemical reduction of hexavalent

chromium

Acid treatment with chromium and rinse

Anodizing with chromium and rinse

Chromate conversion coating and rinse

Electroplating with chromium and rinse

Stripping (paint)

Wet air pollution control - chromium

Chromium drag-out reduction and rinse

Chemical reduction of chelated metals Electroless plating and rinse

Cyanide destruction Alkaline treatment with cyanide and rinse

Electroplating with cyanide and rinse

Cyanide rinsing and rinse

Cyanide drag-out destruction and rinse

Wet air pollution control - cyanide

Solvent hauling Solvent degreasing

a Note - A unit operation can feed more than one treatment unit or in-process pollution prevention technology. EPA

assumed that the model sites commingled all MP&M wastewater generated for treatment by chemical precipitation,

except for wastewater from the Oily Wastes, the Shipbuilding Dry Dock and Railroad Line Maintenance

subcategories, and except for solvent-bearing wastewater which EPA costed for off-site disposal.

Figure 11-2 shows the logic used by the MP&M Design and Cost Model to apply

the in-process technologies and pollution prevention practices to each site. For streams at model

sites that EPA determined to not have technology in place (see Section 11.2.4), EPA applied flow

reductions for each in-process technology as summarized below:

C EPA estimated a 20 to 80 percent flow reduction achieved by converting

the current rinse scheme in place to countercurrent cascade rinsing. 

C EPA assumed centrifugation and pasteurization of machining coolants

reduced coolant use by 80 percent.

C EPA assumed centrifugation of painting water curtains achieved zero

discharge of wastewater through 100 percent reuse of the treated

wastewater in the painting booth (sludge removed from the centrifuge is

contract hauled). 
11.0 - Costs of Technology Bases for Regulations

11-18

For countercurrent cascade rinsing, EPA estimated costs for each individual rinse

stream at a site. EPA assumed that a site combined all wastewater from machining operations

prior to centrifugation and pasteurization of machining coolants and combined wastewater from

painting streams prior to paint curtain centrifugation.

Figure 11-3 presents the logic used by the MP&M Design and Cost Model to

apply the end-of-pipe treatment technologies and practices for the following subcategories:

General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Board,

and Steel Forming and Finishing. In developing costs, EPA assumed sites would segregate

wastewater streams from the unit operations and the in-process pollution prevention technologies

(when applicable) according to pollutant characteristics (chromium, cyanide, chelated metals, oil,

and solvent). Segregation of wastestreams provides for the most efficient and effective treatment

of wastes. Solvent-bearing wastewater streams were contract hauled for off-site disposal, while

the other segregated wastewater streams received preliminary treatment. EPA’s Design & Cost

Model combined the effluent from the preliminary treatment technologies with other wastewater

streams not requiring preliminary treatment then treated the combined wastewater by chemical

precipitation and sedimentation. The Cost Model sends the sludge from chemical precipitation

to thickening and pressure filtration prior to contract hauling for off-site disposal. Finally, the

Cost Model assumes a wastewater discharge from the chemical precipitation and sedimentation

system to either a surface water or POTW according to the model site’s current discharge

destination (see Section 11.3.4 for general discharge status assumptions for sites with multiple

discharge destinations).

Figure 11-4 presents the logic used by the MP&M Design and Cost Model to

apply the end-of-pipe treatment technologies and pollution prevention practices for the Oily

Wastes, Railroad Line Maintenance, and Shipbuilding Dry Dock subcategories. Each of these

subcategories generates wastewater that primarily contains oily constituents; therefore, EPA did

not include chemical precipitation and sedimentation following oil treatment in the Cost Model.

The model provided the following information, as applicable, for each technology

designed for a model site: 

C Total direct capital costs;

C Total direct annual costs;

C Electricity used and associated cost;

C Sludge generation and associated disposal costs;

C Waste oil generation and associated disposal costs;

C Water use reduction and associated cost credit;

C Chemical usage reduction and associated cost credit;

C Effluent flow rate; and

C Effluent pollutant concentrations. 

Section 11.4 provides specific information calculated by each technology module.
11.0 - Costs of Technology Bases for Regulations

11-19

11.3.4 General Assumptions Made During the Costing Effort

This section presents general assumptions that EPA applied throughout the

MP&M Design and Cost Model. Technology-specific assumptions are presented under the

appropriate technology descriptions in Section 11.4.

Calculation of Baseline Parameters

As discussed in Section 11.2.4, EPA determined the technologies in place,

including the operating schedules and the wastewater streams treated as specified in the MP&M

survey by the model site. Using this survey information, EPA modeled each site’s current costs

and pollutant loads, referred to as baseline values. EPA uses baseline values as the basis for

determining the incremental costs and loads associated with each technology option. Before

running the Cost Model for any of the technology options, EPA conducted a baseline run of the

model to determine the following:

C Baseline (survey year) operating and maintenance costs incurred by sites in

1996 dollars;

C Baseline non-water quality impacts such as electricity usage, sludge

generation, and waste oil generation;

C Baseline pollutant loadings; and 

C Capacity flow rate of each wastewater treatment technology in place.

Because the purpose of the baseline run was to simulate the current treatment

practices at each site, this run included technologies (e.g., batch emulsion breaking and gravity

flotation, multimedia filtration) that EPA did not include in the technology options. The baseline

run also reflected treatment combinations currently used by model sites that the Agency did not

use in the technology options (e.g., gravity oil/water separation followed by ultrafiltration, batch

emulsion breaking and gravity flotation followed by dissolved air flotation). As a conservative

estimate for estimating baseline pollutant loadings (loadings prior to compliance with these

proposed regulations), EPA assumed that all sites with treatment currently in place (including

those sites not currently covered by the Metal Finishing regulations) were currently meeting the

long-term average (LTA) concentrations (i.e., design concentrations) for the pollutants limited

under the Metal Finishing effluent guidelines (40 CFR Part 433) and were meeting the LTA

concentrations achieved by EPA’s sampled BAT facilities for other pollutants of concern (i.e.,

those pollutants not regulated under 40 CFR Part 433). For sites that did not report treatment in

place, EPA estimated baseline pollutant loadings on EPA’s unit operation-by-unit operation

sampling data for raw wastewater.

EPA subtracted the baseline values for operating and maintenance costs, nonwater quality impacts, and pollutant loadings from the corresponding values calculated from each
11.0 - Costs of Technology Bases for Regulations

11-20

technology option to determine the incremental impact in relation to the baseline for each

technology option.

End-of-Pipe Technology in Place

EPA designed the Cost Model to account for in-process and end-of-pipe operating

equipment already in place at the model sites. For end-of-pipe treatment technologies, EPA

reviewed information in the surveys to assess which of the treatment technologies included in

each option were in place at the sites. Some sites had no technologies in place, some had

incomplete treatment in place, and others had complete treatment in place. EPA also assessed

the design capacity flow for each treatment unit in place to determine whether each site had

sufficient capacity to treat all of its MP&M process wastewater. The Agency derived design

capacity flow from the larger of the site’s reported survey value or the site’s Cost Model design

capacity flow (as derived from the baseline flow), assuming baseline flow was 78 percent of

capacity (EPA based this assumption on the average value reported in surveys). For some

treatment options, EPA’s Cost Model selected treatment for a wastewater stream (see Table 11-

6) that differed from the treatment utilized by the site at baseline. This situation sometimes

required a treatment unit at a model site to treat additional wastewater streams at the EPA option.

In these situations, the treatment capacity of the technology in place at baseline may have been

insufficient. EPA made the following assumptions regarding capital costs and end-of-pipe

technology capacities:

C If the technology was not in place at the model site, then EPA assigned

capital costs to the site for a treatment unit of sufficient capacity;

C If the technology was in place at the model site with sufficient capacity to

treat all of the wastewater, then EPA assigned no capital costs; and

C If the technology was in place at the model site but with insufficient

capacity to treat all of the wastewater, then EPA assumed the site would

operate the existing system at full capacity and EPA assigned capital costs

to the site for an additional treatment unit to operate in parallel with the

existing unit to treat the additional flow.

Additionally, EPA assumed that some sedimentation and oil treatment systems

qualified as treatment in place for multiple options. For example, a microfiltration system for

solids removal would be considered treatment in place for either microfiltration or clarification

depending on the technology option, while a clarifier would only be considered treatment in

place for clarification. Table 11-7 lists the technologies that EPA considered treatment in place

for various options for both sedimentation and oil treatment.
11.0 - Costs of Technology Bases for Regulations

11-21

Table 11-7 

Sedimentation and Oil Treatment Technologies Considered 

Treatment in Place for Various Technology Options

Technology Specified by Option

Technologies Considered 

Treatment in Place

Microfiltration for solids removal Microfiltration 

Clarification Clarification or microfiltration

Ultrafiltration for oil removal Ultrafiltration

Dissolved air flotation Dissolved air flotation or ultrafiltration

Chemical emulsion breaking and gravity oil/water

separation.

Chemical emulsion breaking and gravity oil/water

separation, batch chemical emulsion breaking and

gravity flotation, dissolved air flotation, or

ultrafiltration

Contract Hauling in Lieu of Treatment

EPA assessed the cost of contract hauling wastewater for off-site treatment

compared to on-site treatment. Because many MP&M sites have flow rates lower than the

minimum design capacity of the treatment unit, EPA determined that it is often less expensive for

a model site to contract haul wastewater for off-site disposal rather than to treat it on site. To

assess contract hauling in lieu of treatment, EPA compared the costs of contract hauling the

wastewater with the costs of the treatment unit that would be used to treat it on site. If contract

hauling was less expensive than treating on site, EPA’s Cost Model assigned the site costs

associated with contract hauling the wastewater. EPA based this determination on individual

technologies and their influent flow rates rather than on the total site wastewater treatment

system. For example, for a particular site, it may be less expensive to contract haul cyanidebearing wastewater in lieu of treatment while still treating all other wastewater streams on site. 

The calculation for determining whether treatment on site was less expensive assumed an

equipment life expectancy of 15 years and an annual interest rate of 7 percent.

EPA compared the following technologies to contract hauling in lieu of treatment:

C Centrifugation and pasteurization of machining coolants;

C Centrifugation of painting water curtains (general metal-bearing waste and

paint sludge);

C Chemical reduction of hexavalent chromium;

C Cyanide destruction;

C Chemical reduction of chelated metals;

C Chemical emulsion breaking and gravity oil/water separation;

C Dissolved air flotation;
11.0 - Costs of Technology Bases for Regulations

11-22

C Ultrafiltration for oil removal;

C Chemical precipitation and sedimentation; and

C Sludge pressure filtration.

In the case of wastewater requiring chemical precipitation and sedimentation

treatment, EPA compared the costs of contract hauling the untreated end-of-pipe wastewater to

the cost of the entire treatment system, which includes chemical precipitation, sedimentation

(gravity clarification or microfiltration), sludge thickening, and pressure filtration.

Equipment Size Ranges

EPA developed equipment cost equations for each component of the treatment

technologies. The validity ranges represent the minimum and maximum sizes (e.g., flow rates,

volume capacities) for which EPA developed the equations. For wastewater streams requiring

equipment with a capacity below the minimum range of validity, the cost model designed the

equipment at the minimum size. For wastewater streams requiring equipment with a capacity

above the maximum range of validity, the cost model designed multiple units of equal capacity to

operate in parallel such that the equipment sizes were within the range of validity. 

Batch Schedules

EPA designed either batch or continuous systems, depending on each model site’s

operating schedule and discharge flow rate. For batch systems, EPA determined the batch

volume and operating schedule to minimize costs. If the volume of wastewater to be treated in a

single day was less than the capacity of the minimum batch system size based on vendor

information, then the Agency altered the site’s wastewater treatment operating schedule such that

the minimum system would be operated at capacity. For example, if the minimum cyanide

destruction system was 480 gallons per batch, and a site generated 80 gallons of cyanide-bearing

wastewater per day, then the Cost Model designed the cyanide destruction system to treat a 480-

gallon batch once every six days.

Dilute Influent Concentrations

In rare cases, high wastewater flow rates at some sites resulted in pollutant

concentrations below the long-term average technology effectiveness concentrations (discussed

in Section 10.0) even after EPA applied its in-process pollution prevention practices to reduce

the site’s flow. In these cases, the Cost Model did not design or provide costs for a technology at

the EPA option for that wastewater stream. When this situation occurred during the baseline run

of the model, the Cost Model assigned costs for technologies in place. 

Discharge Status

EPA classified a stream’s discharge status as direct, indirect, contract haul, reuse,

or zero discharge. Some model sites discharge their wastewater streams to multiple discharge
11.0 - Costs of Technology Bases for Regulations

11-23

destinations at baseline. Although the Cost Model allows segregated streams to be contract

hauled for off-site disposal, it assumes the model site combines the wastewater sent to treatment

prior to chemical precipitation and sedimentation. Therefore, EPA assigned a single discharge

status to each model site based on the following assumptions: 

C EPA considered a site with any combination of individual MP&M streams

with a direct discharging stream a direct discharging site; 

C EPA considered a site with any combination of individual MP&M

streams, except direct, with an indirect discharging stream an indirect

discharging site; and

C EPA considered a site with any combination of individual MP&M

streams, except direct and indirect, a zero discharger/contract-hauled site.

11.4 Design and Costs of Individual Technologies

This section discusses in detail the design and costing of the individual

technologies that comprise the technology options. Additional documentation is included in the

public record for this rulemaking. Table 11-8 presents capital and annual cost equations for the

specific equipment mentioned in each technology description below.

11.4.1 Countercurrent Cascade Rinsing

The Agency applied costs for countercurrent cascade rinses for flowing rinses at

the model sites (see Table 11-6). EPA gave treatment in place credit to facilities with

countercurrent cascade rinsing in place at baseline. The countercurrent cascade rinse module

applies a flow reduction to rinses and a cost associated with the conversion to a two-stage

countercurrent rinse. The Agency assigned flow reductions ranging from approximately 20

percent to 80 percent based on the site’s current PNF and type of rinsing equipment. EPA used

information from the 1996 MP&M Detailed Survey responses to determine the percentages of

flow reductions, as documented in the public record for this rulemaking. (See Section 15.2.4 for

more information on countercurrent cascade rinsing flow reduction as related to the site’s

existing rinse scheme).

EPA applied costs based on the site’s current rinse scheme. The module included

capital and annual costs for the following equipment when necessary.

C A second rinse tank with a volume equal to the volume of the existing

tank; 

C Transfer pumps and piping; and

C An air-agitation system.

EPA did not include additional operating and maintenance costs for

countercurrent cascade rinses because these would be the same as for the original rinse. Direct

annual costs for this module included energy costs and a credit for water-use reduction. EPA
11.0 - Costs of Technology Bases for Regulations

11-24

based the cost credit for water-use savings on the annual flow reduction for each countercurrent

cascade rinse system and an average source water charge (as determined in Section 11.3.2). 
11.0 - Costs of Technology Bases for Regulations

11-25

Table 11-8

MP&M Equipment Cost Equationsa

Equipment Equation Range of Validity

Countercurrent cascade

rinsing

A = [(0.0004*TANKVOL + 0.2243)]*DPY*HPD*0.047]

- [(Y-CCFLOW)*60*HPD*DPY*0.00203]

C = 6.047*TANKVOL + 3784.3 Tank, piping, and

pump

C = 0.5077*TANKVOL + 1077.8 Piping and pump

C = 8*29.67 Labor only

Machine coolant

regeneration system

(including holding tanks)

A = [18*0.047*DPY*HPD] + [(HPD/8)*DPY*29.67] + [(DPY/5)*29.67] +

[0.002*Y*60*HPD*DPY*1.95]+ [0.05*Y*60*HPD*DPY*0.86] -

[0.05*0.80*Y*60*HPD*DPY*9.03] - [0.95*0.8*Y*60*HPD*DPY*0.00203]

Y#14

C = 41,422 Y # 1

C = 110,205 1 < Y # 2

C = 142,831 2 < Y # 6

C = 164,009 6 < Y # 10

C = 191,331 10 < Y # 14

Paint curtain centrifuge A = [0.047*KW*HPD*DPY] + [(HPD/8)*DPY*29.67] + [(DPY/5)*29.67)]

+ [TSS*3.785/106*2.2/0.4*Y*60*HPD*DPY/8.5*3.7]

- [(Y*60*HPD*DPY) - (TSS*3.785/106*2.2/0.4*Y*60*HPD*DPY*0.6/8.34)]*0.00203

Y#53

C = 7,254 (kW = 0.4) Y # 8

C = 10,325 (kW = 1.5) 8 < Y # 13

C = 47,104 (kW = 2.2) 13 < Y # 26

C = 62,936 (kW=3.7) 26 < Y # 53
11-26

Table 11-8 (Continued)

11.0 - Costs of Technology Bases for Regulations

Equipment Equation Range of Validity

Feed system, aluminum

sulfate (alum)

A = [1.36*HPD*DPY*0.047] + [0.0006615*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y < 350

A = [1.49*HPD*DPY*0.047] + [0.0006615*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y $ 350

C = 9.7882*Y + 9,718.7

Feed system, calcium

chloride, continuous

A = [[(0.0061*Y)+1.1696]*HPD*DPY*0.047] + [0.00125*Y*60*HPD*DPY] +

[(HPD/8)*DPY*29.67] + [(DPY/5)*29.67]

Y # 350

C = 28.805*Y + 10,683

Feed system, calcium 

hydroxide (lime), continuous

A = [[(0.0006*Y)+1.2961]*HPD*DPY*0.047] + [0.000117*Y*60*HPD*DPY] +

[(HPD/8)*DPY*29.67] + [(DPY/5)*29.67]

Y # 350

C = 24.586*Y + 12,830

Feed system, ferric sulfate,

continuous

A = [[(0.0009*Y)+1.3313]*HPD*DPY*0.047] + [0.0000434*Y*60*HPD*DPY] +

[(HPD/8)*DPY*29.67] + [(DPY/5)*29.67]

Y # 350

C = 11.56*Y + 9,762.9

Feed system, polymer A = [0.2833*HPD*DPY*0.047] + [0.001*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y < 10

C = 3,686

A = [[(0.0034*Y)+1.4171]*HPD*DPY*0.047] + [0.001*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

 10 # Y # 4,000

C = 20.685*Y + 9,822

Feed system, sodium

hydroxide, continuous

(caustic)

A = [0.1864*HPD*DPY*0.047] + [0.0042*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y < 10

C = 5,120

A = [((0.0071*Y)+1.1584)*HPD*DPY*0.047] + [0.0042*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67]

+ [(DPY/5)*29.67]

 10 # Y # 4,000

C = 77.564*Y + 21,506
11-27

Table 11-8 (Continued)

11.0 - Costs of Technology Bases for Regulations

Equipment Equation Range of Validity

Feed system, sulfuric acid A = [0.0373*HPD*DPY*0.047] + [0.000222*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y < 10

C = 4,938

A = [[(0.0023*Y)+1.683]*HPD*DPY*0.047] + [0.000222*Y*60*HPD*DPY] +

[(HPD/8)*DPY*29.67] + [(DPY/5)*29.67]

10 # Y # 4,000

C = 56.416*Y + 17,769

Chemical emulsion breaking,

coalescent plate separator

(gravity oil/water separator)

[requires sulfuric acid, alum,

and polymer feed systems]

A = [(0.0512*Y+0.4524)*HPD*DPY*0.047] + [29.67*(HPD/8)*DPY] + [(DPY/5)*29.67] +

[3.664*Y*HPD*DPY]

Y # 860

C = 328.83*Y + 28,104

Dissolved air flotation

[requires lime, ferric sulfate,

and polymer feed systems]

See ultrafiltration for oil removal. Y < 4.42

A = [(0.0728*Y+3.072)*HPD*DPY*0.047] + [0.0045*Y*60*HPD*DPY] + [29.67*HPD*DPY] +

[(DPY/5)*29.67] + [0.86*0.0003*Y*60*HPD*DPY] + [0.86*0.071*Y*60*HPD*DPY]

 4.42 # Y # 350

C = 1,125.4*Y + 137,936

Ultrafiltration for oil

removal

A = [(0.71*Y+5.46)*HPD*DPY*0.047] + [0.4*Y+0.3] + [0.5*HPD*DPY*29.67] + [(DPY/5)*29.67] +

[65.78*Y+193.46] + [(27,123*Y/24*365*60)*0.86*60*HPD*DPY]

Y # 406

C = 3,596*Y + 235,146

Batch oil-emulsion breaking

with gravity flotation 

[requires sulfuric acid, alum,

and polymer feed systems]

See dissolved air flotation. Y < 100

A = [(0.65*Y+49.7)*HPD*DPY*0.047] + [HPD*DPY*29.67] + [(DPY/5)*29.67] +

[0.022*Y*60*HPD*DPY*0.86]

100 # Y # 300

C = 17,204*Y + 2,000,000

Chromium reduction system,

sodium metabisulfite

A = [2.4225*HPD*DPY*0.047] + [0.002608*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y # 410

C = 261.7*Y + 24,249
11-28

Table 11-8 (Continued)

11.0 - Costs of Technology Bases for Regulations

Equipment Equation Range of Validity

Alkaline chlorination with

hypochlorite feed system

(for cyanide destruction)

A = [4.845*HPD*DPY*0.047] + [0.012418*Y*HPD*DPY*60] + [0.125*HPD*DPY*29.67] +

[(DPY/5)*29.67]

1 # Y # 200

C = 30,137*Y0.1866

Chelation breaking with

dithiocarbamate treatment

A = [2.4225*HPD*DPY*0.047] + [0.000583*Y*60*HPD*DPY] + [(HPD/8)*DPY*29.67] +

[(DPY/5)*29.67]

Y # 45

C = 261.7*Y + 24,249

Chemical precipitation

[requires sulfuric acid,

caustic, and polymer feed

systems]

A = [0.932*HPD*DPY*0.047] + [(DPY/5)*29.67] + [(HPD/8)*DPY*29.67] Y < 5

C = 626.6*Y + 8,550

A = [((0.0571*Y)+0.0123)*HPD*DPY*0.047] + [(DPY/5)*29.67] + [(HPD/8)*DPY*29.67] 5 # Y # 4,000

C = 784.547*Y + 34,216

Clarifier, slant-plate

(lamella)

A = 2*(DPY/5)*29.67 Y < 2

C = 9,740 2 # Y < 10

C = 15,057 10 # Y # 4,000

C = 74.896*Y + 31,401

Filtration, multimedia A = [[(0.0504*Y)+1.0139]*HPD*DPY*0.047] + [(HPD/8)*DPY*29.67] + [(DPY/5)*29.67] Y # 4,000

C = 240.85*Y + 27,269

Microfiltration system for

metals removal

A = [(0.3*Y+6.3)*HPD*DPY*0.047] + [3.4*Y] + [0.5*HPD*DPY*29.67] + [(DPY/5)*29.67] +

[184.2*Y+155.2]

Y # 406

C = 1,728.3*Y + 69,337

Sludge thickening A = [0.246*HPD*DPY*0.047] + [2*(DPY/5)*29.67] Y < 42

C = 74.306*Y*60 + 3,746

A = [3.7*HPD*DPY*0.047] + [2*(DPY/5)*29.67] 42 # Y # 350

C = 35.265*Y + 66,106
11-29

Table 11-8 (Continued)

11.0 - Costs of Technology Bases for Regulations

Equipment Equation Range of Validity

Filter press, plate-and-frame A = [(60 + (30 * DPY * 2)) * NUM] + [FT3*DPY*7.48*1.95] CFT3 # 6

A = [(60 + (60 * DPY * 2)) * NUM] + [FT3*DPY*7.48*1.95] CFT3 # 12

A = [(60 + (90 * DPY * 2)) * NUM] + [FT3*DPY*7.48*1.95] CFT3 > 12

C = [1,658.8 * FT3] + 17,505 0.85 < FT3 # 76.5

Variable Definitions:

C = Direct capital costs (1996 dollars).

A = Direct annual costs (1996 dollars).

Y = Influent equipment flow (gallons per minute).

HPD = Operation hours per day.

DPY = Days of operation per year.

FT3 = Daily cake volume (FT3) from all presses.

TANKVOL = Volume of countercurrent rinsing tank (gallons).

CCFLOW = Flow rate after countercurrent rinsing is supplied (gallons per minute).

kW = Kilowatts.

CFT3 = Cake volume (FT3) per cycle per press (assume two cycles per day).

NUM = Number of filter presses.

TSS = Influent TSS concentration (mg/L).

aAll costs are calculated in 1996 dollars. 
11.0 - Costs of Technology Bases for Regulations

11-30

11.4.2 Centrifugation and Pasteurization of Machining Coolant 

EPA applied costs for centrifugation and pasteurization of machining coolant for

machining and grinding operations discharging water-soluble or emulsified coolant (listed in

Table 11-6). The treatment system used to estimate compliance costs consisted of a liquid-liquid

separation centrifuge for removal of solids and tramp oils and a pasteurization unit to reduce

microbial growth. The module added 50 percent excess capacity to each site’s system to account

for fluctuations in production. The Agency based capital and annual costs on packaged systems

of different capacities. Flow rates of greater than 14 gallons per minute required multiple

systems. The various size systems included the following equipment: 

C High-speed, liquid-liquid separation centrifuge;

C Pasteurization unit; and

C Holding tanks for large volume applications.

Direct annual costs included operating and maintenance labor and materials,

energy costs, sludge and waste oil disposal costs, and a cost credit for water- and coolant-use

reduction. EPA estimated maintenance labor at one hour per week and operating labor at one

hour per shift. 

Based on site visit and vendor information, EPA assumed that this technology can

reduce coolant discharge by 80 percent. The Agency based the amount of coolant and water

saved on the site recycling 80 percent of the coolant and discharging a 20 percent blowdown

stream to oil treatment. EPA assumed the coolant solution to be 95 percent water and 5 percent

coolant, based on site visit and vendor information. 

11.4.3 Centrifugation of Painting Water Curtains 

EPA applied costs for centrifugation of painting water curtains to painting water

curtain operations (listed in Table 11-6). The capital and annual costs include a centrifuge and a

holding tank large enough to hold flow for one hour. 

Direct annual costs included operating and maintenance labor and materials,

energy costs, sludge disposal costs, and a cost credit for water-use reduction. EPA estimated

maintenance labor at one hour per week and operating labor at one hour per shift. 

EPA assumed that the model site reused all water discharged from the

centrifugation system in painting operations, and the site contract hauled the sludge from the

system as a hazardous/nonhazardous sludge. EPA estimated contract hauling costs using the

average paint sludge hauling costs reported in the 1996 MP&M Detailed Surveys. Because

actual disposal costs will depend on site-specific conditions (e.g., paint type and spray-gun

cleaner requirements), EPA believes that the average cost for all paint sludge disposal reported in

the surveys, regardless of RCRA hazard classification, is a better estimate than using either the
11.0 - Costs of Technology Bases for Regulations

11-31

costs for RCRA hazardous or RCRA nonhazardous paint sludges. (See Table 11-4 for contract

hauling costs and Section 11.4.4 below for more detailed information.)

11.4.4 Contract Hauling

The Agency estimated costs for off-site treatment and disposal of various types of

wastes generated on site. These waste types include:

C Painting and paint stripping/solvent wastewater;

C Paint sludge;

C Wastewater containing oil and grease and organic pollutants;

C Waste oils/sludges;

C Chromium-bearing wastewater;

C Cyanide-bearing wastewater;

C Chelated metal-bearing wastewater;

C General metal-bearing wastewater; and

C Metal-bearing sludge.

Except for F006 hazardous waste, EPA estimated costs for off-site treatment and

disposal of each waste type in dollars per gallon of waste using averages of cost data provided in

the 1996 MP&M Detailed Surveys for contract hauling specific waste streams. The following

briefly summarizes how EPA applied these costs throughout the MP&M Design and Cost Model

(additional details are provided in the public record for this rulemaking);

C EPA estimated a cost of $2.85 per gallon for contract hauling painting and

paint stripping wastewater for off-site treatment and disposal based on the

cost for contract hauling solvent-bearing wastewater as reported in the

1996 MP&M Detailed Surveys.

C EPA estimated a cost of $3.70 per gallon for contract hauling paint sludge

generated by the painting water curtain centrifugation system for

landfilling as a hazardous/nonhazardous waste based on the values

reported in the 1996 MP&M Detailed Surveys. 

C EPA estimated a cost of $1.33 per gallon for contract hauling wastewater

bearing oil and grease or other organic pollutants for off-site treatment

based on the values reported in the 1996 MP&M Detailed Surveys. EPA

used this estimate for sites at which the Cost Model determined contract

hauling to be less expensive than treatment on site (machining coolant

centrifugation and pasteurization system, chemical emulsion breaking and

gravity oil/water separation, dissolved air flotation, or ultrafiltration for oil

removal).
11.0 - Costs of Technology Bases for Regulations

11-32

C EPA estimated a cost of $0.86 per gallon for contract hauling waste oil

generated by machining coolant centrifugation and pasteurization,

chemical emulsion breaking and gravity oil/water separation, dissolved air

flotation, and ultrafiltration for oil removal based on the values reported in

the 1996 MP&M Detailed Surveys. Dissolved air flotation also generated

a waste sludge hauling cost, which was approximated using the waste oil

cost.

C EPA estimated a cost of $3.51 per gallon for contract hauling hexavalent

chromium-bearing wastewater for off-site treatment based on the values

reported in the 1996 MP&M Detailed Surveys. EPA used this estimate for

sites at which the Cost Model determined contract hauling to be less

expensive than the chemical reduction of hexavalent chromium system.

C EPA estimated a cost of $5.64 per gallon for contract hauling cyanidebearing wastewater for off-site treatment based on the values reported in

the 1996 MP&M Detailed Surveys. EPA used this estimate for sites at

which the Cost Model determined contract hauling to be less expensive

than the cyanide destruction system.

C EPA estimated a cost of $1.40 per gallon for contract hauling chelated

metal-bearing wastewater for off-site treatment based on the values

reported in the 1996 MP&M Detailed Surveys. EPA used this estimate for

sites at which the Cost Model determined contract hauling to be less

expensive than the chemical reduction of chelated metals system.

C EPA estimated a cost of $2.00 per gallon for contract hauling metalbearing wastewater for off-site treatment based on the values reported in

the 1996 MP&M Detailed Surveys. EPA used this estimate for sites at

which the Cost Model determined contract hauling to be less expensive

than the chemical precipitation and sedimentation system and the sludge

pressure filtration system.

C EPA estimated a cost of $1.95 per gallon for contract hauling metalbearing sludge, generated by the sludge pressure filtration system and the

machining coolant centrifugation and pasteurization system, for landfilling

as an F006 hazardous waste based on the value reported in Pollution

Prevention and Control Technology for Plating Operations (3).

11.4.5 Feed Systems

EPA estimated costs for generic feed systems. Where data were available, EPA

incorporated treatment-specific feed systems and dosages into the treatment system costs. If this

information was unavailable, EPA used literature information or engineering judgement to select
11.0 - Costs of Technology Bases for Regulations

11-33

the dosages. The Agency used the following generic chemical dosages to estimate annual

operating and maintenance costs:

C Polymer feed system - 20 mg/L (3);

C Continuous sodium hydroxide feed system -1,685 mg/L (3);

C Continuous hydrated lime feed system - 376 mg/L (3);

C Continuous sulfuric acid feed system - 699 mg/L (3);

C Continuous ferric sulfate feed system - 74 mg/L (4);

C Continuous aluminum sulfate (alum) feed system - 648mg/L (4); and

C Continuous calcium chloride feed system - 830 mg/L (3).

The discussions for treatment systems that use these generic feed system costs

and/or dosages refer back to this section. Capital and annual costs from these feed systems were

not reported individually in Cost Model outputs but were summed into the overall treatment

system capital and annual costs. The capital and annual costs for the following equipment were

included:

C Raw material storage tank;

C Day storage tank with mixer;

C Chemical metering pumps;

C pH controller; and

C Supporting piping and valves.

EPA developed low-flow polymer, sodium hydroxide, and sulfuric acid feed

modules with lower fixed capital and energy costs for flow rates less than 600 gallons per hour. 

The alum feed system was given lower energy costs for systems below 350 gallons per hour. 

Direct annual costs included operating and maintenance labor, energy costs, and chemicals. The

polymer module also included an annual maintenance material cost that was 10 percent of the

capital cost.

11.4.6 Chemical Emulsion Breaking and Gravity Oil/Water Separation

EPA estimated costs for chemical emulsion breaking and gravity oil/water

separation systems to separate and remove oil and grease and organic pollutants. The Agency

assumed that Model sites commingled all oil-bearing wastewater streams prior to treatment. 

Table 11-6 lists these wastewater streams.

For chemical emulsion breaking systems, the module included capital and annual

costs for the following equipment: 

C Flow equalization tank;

C Two emulsion breaking tanks;

C Two mixers;

C Sulfuric acid feed system (see Section 11.4.5);
11.0 - Costs of Technology Bases for Regulations

11-34

C Polymer feed system (see Section 11.4.5);

C Alum feed system (see Section 11.4.5); and

C Wastewater pumps.

Emulsion breaking was followed by oil removal using a coalescent plate

separator. For oil removal systems, the module included capital and annual costs for the

following equipment:

C Feed pumps; and

C Oil/water separator.

Direct annual costs included operating and maintenance labor and materials,

energy costs, raw materials (e.g,. sulfuric acid, alum, polymer), and waste oil disposal costs. 

Waste oil was contract hauled for off-site reclamation. EPA adjusted effluent flow rates for

removal of waste oil, which it estimated to be 7.1 percent of the influent flow, based on MP&M

survey data. Depending on the subcategory, EPA assumed model sites discharged the effluent

from this system either to surface water or a POTW or to the chemical precipitation and

sedimentation system. The Cost Model estimated costs associated with achieving the long-term

average effluent concentrations of oil and grease and other pollutants removed by chemical

emulsion breaking and gravity oil/water separation (see Section 10.3).

11.4.7 Dissolved Air Flotation

For the shipbuilding and railroad line maintenance subcategories, EPA estimated

costs for dissolved air flotation systems to separate and remove oil and grease, suspended solids,

and organic pollutants. The Agency assumed that model sites commingled all oil-bearing

wastewater streams prior to treatment. Table 11-6 lists these wastewater streams.

The module included capital and annual costs for the following equipment: 

C Flow equalization tank;

C Feed pumps;

C Oil/water separator;

C Chemical treatment tank;

C Lime feed system (see Section 11.4.5);

C Ferric sulfate feed system (see Section 11.4.5);

C Polymer feed system (see Section 11.4.5);

C Dissolved air flotation system with pressure tank and programmable logic

controller (PLC);

C Oil storage tank; and

C Final pH adjustment tank.

Direct annual costs included operating and maintenance labor and materials,

energy costs, raw materials (e.g., hydrated lime, ferric sulfate, polymer), and waste oil and sludge
11.0 - Costs of Technology Bases for Regulations

11-35

disposal costs. EPA costed waste oil and sludge for contract hauling for off-site reclamation. 

Hydrated lime and ferric sulfate were added to the treatment flow, while the polymer volume was

considered negligible. EPA adjusted effluent flow rates for removal of waste oil and sludge,

which were respectively estimated as 7.1 percent and 0.03 percent of the influent flow, based on

the MP&M survey data. EPA assumed model sites discharged effluent from this system either to

surface water or a POTW. The Cost Model estimated costs associated with achieving long-term

average effluent concentrations of oil and grease, total suspended solids, and other pollutants

treated by dissolved air flotation (see Section 10.3). Because dissolved air flotation systems are

not typically used for flow rates less than 265 gallons per hour, EPA costed model sites with

flows less than 265 gph for ultrafiltration for oil removal.

11.4.8 Ultrafiltration System for Oil Removal

EPA estimated costs for ultrafiltration systems to separate and remove oil and

grease, suspended solids, and organic pollutants. The Agency assumed that model sites

commingled all oil-bearing wastewater streams prior to treatment. Table 11-6 lists these

wastewater streams.

The module included capital and annual costs for the following equipment: 

C Spiral-wound membrane filtration modules;

C Process and chemical tanks;

C Steel skid;

C Recirculation tank;

C Recirculation pump;

C Bag filter;

C Fix-mounted cleaning system;

C Sludge pump; and

C Electrical components (pH control/monitoring, temperature control, flow

meter, pressure gauges).

Flow rates greater than 406 gallons per minute required multiple systems. 

Direct annual costs included operating and maintenance labor and materials,

energy costs, cleaning chemicals, membrane replacement, and waste oil disposal costs. The Cost

Model assumed model sites contract hauled waste oil for off-site reclamation. Depending on the

subcategory, EPA assumed the model sites discharged the effluent from this system either to

surface water or a POTW or to the chemical precipitation and sedimentation system. EPA

adjusted effluent flow rates for removal of waste oil, which was estimated as 5.2 percent of the

influent flow, based on MP&M survey data. The Cost Model estimated costs associated with

achieving long-term average effluent concentrations of oil and grease, total suspended solids, and

other pollutants treated by ultrafiltration (see Section 10.3).
11.0 - Costs of Technology Bases for Regulations

11-36

11.4.9 Batch Oil Emulsion Breaking with Gravity Flotation

EPA estimated costs for batch oil emulsion breaking with gravity flotation

systems to separate and remove oil and grease, suspended solids, and organic pollutants. The

Agency assumed that model sites commingled all oil-bearing wastewater streams prior to

treatment.

Although this technology is not part of the MP&M technology options, EPA gave

treatment in place credit for chemical emulsion breaking and gravity oil/water separation to sites

with batch emulsion breaking with gravity flotation in place at baseline. The module included

capital and annual costs for the following equipment: 

C Polymer feed system (see Section 11.4.5);

C Sulfuric acid feed system (see Section 11.4.5);

C Alum feed system (see Section 11.4.5);

C Two mechanically cleaning bar screens;

C Three batch wastewater treatment tanks;

C Two segregated waste tanks;

C Three skim and saleable oil storage tanks;

C Two oil cooking tanks;

C Pumps;

C One air compressor;

C Six mixers (segregation, saleable oil, and oil cooker tanks); and

C Ancillary equipment (pipes and valves, heat trace, controls, and PLC).

Direct annual costs included operating and maintenance labor, energy costs, raw

materials (e.g., polymer, sulfuric acid, alum), and waste oil disposal costs. EPA assumed model

sites contract hauled waste oil for off-site reclamation. Sulfuric acid and alum were added to the

treatment flow, while the polymer volume was considered negligible. The effluent from this

system was discharged to the chemical precipitation and sedimentation system. EPA adjusted

effluent flow rates for removal of waste oil, which was estimated as 2.2 percent of the influent

flow, based on MP&M survey data. The Cost Model estimated costs associated with achieving

long-term average effluent concentrations of oil and grease, total suspended solids, and other

pollutants removed by this technology. For baseline, EPA used this technology for flow rates

greater than 6,000 gallons per hour, whereas EPA used dissolved air flotation for flow rates

between 265 and 6,000 gallons per hour and ultrafiltration for oil removal for flow rates less than

265 gallons per hour.

11.4.10 Chemical Reduction of Hexavalent Chromium

EPA estimated costs for batch and continuous systems to reduce hexavalent

chromium to trivalent chromium prior to chemical precipitation and sedimentation. The Agency

assumed that model sites commingled all chromium-bearing wastewater streams prior to
11.0 - Costs of Technology Bases for Regulations

11-37

treatment and that all chromium in the wastewater was in the hexavalent form. Table 11-6 lists

the chromium-bearing wastewater streams.

 The Agency estimated costs for batch treatment for flow rates less than or equal

to 600 gallons per day, and continuous systems for flow rates greater than 600 gallons per day. 

The module included capital and annual costs for the following equipment: 

C Fiberglass reaction tank;

C Mixer;

C Sulfuric acid feed system;

C Sodium metabisulfate feed system;

C Flow equalization tank;

C Effluent pump; and

C pH and Oxidation-Reduction Potential (ORP) meters.

Direct annual costs included operating and maintenance labor and materials,

energy costs, and raw materials (e.g., sulfuric acid, sodium metabisulfite). EPA based flow

dependent costs on the volume of wastewater from chromium-bearing unit operations through

the system, before treatment chemicals were added to the flow. EPA assumed model sites

discharged effluent from this system to the chemical precipitation and sedimentation system. 

Although hexavalent chromium does not have a long-term average effluent concentration from

chromium reduction systems (see Section 10.3), the Cost Model estimated costs associated with

reducing hexavalent chromium. EPA also assumed that all other pollutant concentrations

(including total chromium) remained unchanged in this treatment unit.

11.4.11 Cyanide Destruction

EPA estimated costs for batch and continuous alkaline chlorination systems to

destroy cyanide prior to chemical precipitation and sedimentation. The Agency assumed that

model sites commingled all cyanide-bearing wastewater streams prior to treatment. Table 11-6

lists these wastewater streams. EPA assumed that model sites did not send wastestreams that did

not contain cyanide to the cyanide destruction system.

The Agency estimated costs for batch treatment for flow rates less than or equal to

600 gallons per day, and continuous systems for flow rates greater than 600 gallons per day. The

cost model included capital and annual costs for the following equipment: 

C Two reaction tanks (batch treatment uses a single tank, with the second

tank operating as a batch-holding tank);

C Mixers;

C Sodium hydroxide feed system;

C Sulfuric acid feed system;

C Sodium hypochlorite feed system;

C Effluent pumps; and
11.0 - Costs of Technology Bases for Regulations

11-38

C pH and ORP meters.

Direct annual costs included operating and maintenance labor and materials,

energy costs, and raw materials (e.g., sodium hydroxide, sulfuric acid, sodium hypochlorite). 

EPA based flow dependent costs on the volume of wastewater from cyanide-bearing unit

operation through the system, before treatment chemicals were added to the flow. The Agency

assumed model sites discharged effluent from this system to the chemical precipitation and

sedimentation system. The Cost Model estimated costs associated with achieving the long-term

effluent concentrations of total and amenable cyanide from cyanide destruction systems. EPA

also assumed that all other pollutant concentrations remained unchanged in this treatment unit.

11.4.12 Chemical Reduction/Precipitation of Chelated Metals 

EPA estimated costs for batch and continuous chemical reduction/precipitation of

chelated metal systems to break and precipitate electroless plating complexes (e.g., copper or

nickel complexes) prior to chemical precipitation and sedimentation. The Agency assumed that

model sites commingled all chelated-metal-bearing wastewater streams prior to treatment. Table

11-6 lists the chelated-metal-bearing wastewater streams.

The Agency costed batch treatment for flow rates less than or equal to 600 gallons

per day, and continuous systems for flow rates greater than 600 gallons per day. The cost model

included capital and annual costs for the following equipment: 

C Fiberglass reaction tank;

C Mixer;

C Sulfuric acid feed system;

C Dithiocarbamate feed system;

C Flow equalization tank;

C Effluent pump; and

C pH and ORP meters.

Direct annual costs included operating and maintenance labor and materials,

energy costs, and raw materials (e.g., sulfuric acid, dithiocarbamate). EPA based flow dependent

costs on the volume of wastewater from chelated-metal-bearing unit operations through the

system, before treatment chemicals were added to the flow. The Agency assumed that model

sites discharged effluent from this system to the chemical precipitation and sedimentation

system. Based on analytical data for these systems, EPA assumed that concentrations of carbon

disulfide and dithiocarbamate increased across the system.

11.4.13 Chemical Precipitation

The Agency estimated costs for continuous chemical precipitation systems. EPA

costed low-flow systems for model sites with influent flow rates less than or equal to 300 gallons

per hour. EPA assumed that the model sites commingled all MP&M wastewater generated for
11.0 - Costs of Technology Bases for Regulations

11-39

treatment by this technology, except for wastewater from the Oily Wastes, the Shipbuilding Dry

Dock and the Railroad Line Maintenance subcategories, and except for solvent-bearing

wastewater which EPA costed for off-site disposal.

The module included capital and annual costs for the following equipment:

C Sulfuric acid feed system (see Section 11.4.5);

C Polymer feed system (see Section 11.4.5);

C Caustic feed system (see Section 11.4.5);

C Equalization tank;

C Rapid-mix tank for precipitation;

C Flocculation tank;

C Final pH-adjustment tank;

C System feed pumps; and 

C Rapid and flocculation mixers.

The module assumed that the total suspended solids leaving the chemical

precipitation system was equivalent to the sum of influent total suspended solids and the

dissolved solids that are converted to suspended solids. The approach for calculating suspended

solids from dissolved solids is documented in the public record for this rulemaking. Additional

flow from treatment chemical addition was considered negligible. EPA designed the Cost Model

to include recycled water from the sludge thickener and filter press. The Agency assumed that

model sites discharged effluent from this system to either clarification or microfiltration. Direct

annual costs included operating and maintenance labor, energy costs, and raw materials (e.g.,

sulfuric acid, polymer, caustic).

11.4.14 Slant-Plate Clarifier

The Agency estimated costs for slant-plate (lamella) clarifier systems. EPA

costed low-flow systems for model sites with influent flow rates less than or equal to 600 gallons

per hour. This system treated effluent from the chemical precipitation system. 

The module included capital and annual costs for the following equipment: 

C Slant-plate clarifier; and

C One-time 80-hour training cost for operators to meet MP&M clarifier

limits instead of the baseline 40 CFR Part 433 Metal Finishing effluent

guideline limits.

The Cost Model estimated costs associated with achieving long-term average

effluent concentrations for all pollutants treated by chemical precipitation with clarification (see

Section 10.3). EPA calculated the amount of sludge generated by this system using site-specific

influent pollutant concentration data for the commingled wastewater. The Agency assumed the

sludge to be 3 percent solids and costed for discharge to a sludge-thickening tank. EPA assumed
11.0 - Costs of Technology Bases for Regulations

11-40

that model sites discharge the effluent from this system to surface water or a POTW. Direct

annual costs included maintenance labor and materials. EPA considered operating labor as part

of chemical precipitation and accounted for pumps in the chemical precipitation and the sludgethickening modules.

11.4.15 Multimedia Filtration

The Agency estimated costs for a multimedia filter to continuously remove

filterable suspended solids. The system was designed as a polishing step for effluent from the

clarifier. Although EPA did not include this technology in the MP&M technology options, it

gave treatment in place credit to sites with multimedia filters in place.

The module included capital and annual costs for the following equipment: 

C Multimedia filter skid;

C Holding tank for clarifier effluent (clearwell); and

C Media filter feed pump.

EPA assumed pollutant concentrations in the effluent from these systems to be

equal to the clarifier long-term average concentrations except for total suspended solids, which

was reduced 35 percent across this system based on MP&M sampling data. The Agency

assumed filter backwash to be 1.2 percent of the influent flow to the chemical precipitation unit. 

EPA assumed model sites discharged filtrate from this system to surface water or a POTW. 

Direct annual costs included operating and maintenance labor and energy costs. EPA

incorporated waste disposal costs from solids into the filter press module at sites operating

multimedia filters.

11.4.16 Microfiltration for Solids Removal

The Agency estimated costs for continuous chemical precipitation systems

followed by microfiltration for solids separation. 

The module included capital and annual costs for the following equipment: 

C Tubular membrane filtration modules; 

C Carbon steel skid; 

C Recirculation tank; 

C Recirculation pump; 

C Air back pulse system; 

C Cleaning system; 

C Sludge pump; and 

C All associated instruments and controls.

Flow rates greater than 406 gallons per minute required multiple systems.
11.0 - Costs of Technology Bases for Regulations

11-41

The Cost Model estimated costs associated with achieving long-term average

effluent concentrations for all pollutants treated by chemical precipitation followed by

microfiltration systems (see Section 10.3). EPA calculated the amount of sludge generated by

this system using site-specific influent pollutant concentration data for the commingled

wastewater. The Agency assumed the sludge to be 3.2 percent solids and costed for discharge to

a sludge-thickening tank. EPA assumed model sites discharged the effluent from this system to

surface water or a POTW. Direct annual costs included operating and maintenance labor and

materials (e.g., replacement membranes, cleaning chemicals), and energy costs.

11.4.17 Sludge Thickening

The Agency estimated costs for sludge thickening by gravity settling for the

sludge discharged from the chemical precipitation and sedimentation system. EPA assumed the

sludge-thickening system to discharge 60 percent of influent flow as sludge, thus increasing the

solids content of the sludge from 3 percent to 5 percent for clarifier effluent and from 3.2 percent

to 5.3 percent for microfiltration effluent prior to further dewatering in the sludge pressure

filtration system. The module included capital and annual costs for the following equipment: 

C Sludge-thickening unit (package system); and

C Clarified water return pump.

EPA costed for model sites to discharge the sludge from this system to the sludge

pressure filtration system. The Agency assumed model sites returned the remaining 40 percent of

influent flow back to the chemical precipitation system as supernatant and it included this flow in

its design. Direct annual costs included operating and maintenance labor and energy costs.

11.4.18 Sludge Pressure Filtration

The Agency estimated costs for the number of plate-and-frame filter presses

needed to increase the solids content of the sludge from approximately 5 percent to 35 percent

prior to contract hauling for off-site disposal. The module included capital and annual costs for

the following equipment: 

C Recessed plate or plate-and-frame filter press; and

C Two double-diaphragm sludge pumps.

Direct annual costs included operating and maintenance labor and sludge disposal

costs. The Cost Model assumes model sites discharge the filtrate from this system to the

chemical precipitation and sedimentation system.
11.0 - Costs of Technology Bases for Regulations

11-42

11.5 References

1. U.S. Environmental Protection Agency. Economic, Environmental, & Benefits

Analysis of the Proposed Metal Products & Machinery Rule. EPA-821-B-00-008,

December 2000.

2. RSMeans Building Construction Cost Data, 56th Annual Edition, 1998, page 594. 

Historical Cost Indexes.

3. Cushnie, George C., CAI Engineering (prepared for NCMS/NAMF). Pollution

Prevention and Control Technology for Plating Operations.

4. U.S. Environmental Protection Agency. MP&M sampling data.
11.0 - Costs of Technology Bases for Regulations

11-43

Industrial process

wastewater streams

In-process

flow control

and pollution

prevention

End-of-pipe

treatment

Discharge to surface

water or POTW

Is the 

current option

being analyzed

2, 4, 6, 8,

or 10?*

Yes

No

* See Section 9 for descriptions of the 10 technology options.

Figure 11-1. Relationship Between In-Process and End-of-Pipe Technologies and Practices
11.0 - Costs of Technology Bases for Regulations

11-44

Individual

process wastewater

streams

Countercurrent

cascade rinse

Is this a

wastewater

rinse

stream?

Yes

Is this

rinse stream

applicable for

flow

reduction?

Discharge

to end-of-pipe

treatment

system

Does the

wastewater

contain paint or

machining

coolant?

No

Combine

machining

coolant

wastewater

streams

Centrifugation

and

pasteurization

of machining

coolants

Discharge

to end-of-pipe

treatment

system

No No

Combine

paint

curtain

wastewater

streams

Centrifugation

of

painting

water

curtains

Zero discharge

to end-of-pipe

treatment

system

Yes Yes

Figure 11-2. Components of Total Capital Investment
11.0 - Costs of Technology Bases for Regulations

11-45

Combine

chelated

metal-bearing

wastewater

Combine

solvent-bearing

wastewater

Combine

cyanidebearing

wastewater

Combine

chromiumbearing

wastewater

Wastewater streams from

individual processes or

in-process controls

Does the

wastewater

contain chromium,

cyanide, chelated

metal, oil, or 

solvent?

Chemical

reduction of

chelated metals

(sulfuric acid,

dithiocarbamate)

Cyanide

destruction

(sodium

hypochlorite,

caustic,

sulfuric acid)

Chemical

reduction of

hexavalent

chromium

(sulfuric acid, 

sodium

metabisulfate)

Combine all

wastewater

streams

Contract haul

for off-site 

treatment

and disposal

Combine

oil-bearing

wastewater

Chemical 

emulsion

breaking 

(polymer, alum, 

sulfuric acid)

Ultrafiltration

Gravity

oil/water

separation

Oil

reclaim/

disposal

Option 1 or 2 Option 3 or 4

Oily

waste

Chemical

precipitation

(sulfuric acid,

polymer,

caustic)

Option 1 or 2 Option 3 or 4

Gravity

clarification

Membrane

filtration

Discharge to

surface water

or POTW

Wastewater

Sludge

No

Sludge

thickening

Sludge

pressure

filtration

Contract haul

for off-site

disposal

Yes

Sludge

Sludge

Sludge

Supernatant

Filtrate

Figure 11-3. Logic Used to Apply End-of-Pipe Technologies and Practices for the Following

Subcategories: General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed

Wiring Board, and Steel Forming and Finishing
11.0 - Costs of Technology Bases for Regulations

11-46

Wastewater streams from

individual processes or

in-process controls

Chemical emulsion

breaking (polymer,

alum, sulfuric acid)

Ultrafiltration

What

subcategory

is the site

in?

Oily wastes

Railroad line maintenance

or shipbuilding dry dock

Is 

the option

5 or 6 or

7 or 8?*

Is the

option

7 or 8 or

9 or 10?*

Dissolved air

floatation (lime,

polymer, 

ferric sulfate)

Option 5 or 6 Option 9 or 10

Gravity

oil/water

separation

Oil

reclaim/

disposal

Oily waste

Sludge

Oily waste

Discharge to

surface water

or POTW

Option 7 or 8

Oil waste Wastewater

Wastewater Wastewater

* See Section 9 for descriptions of the 10 technology options.

Figure 11-4. Logic Used to Apply End-of-Pipe Technologies

and Practices for the Following Subcategories: Oily Waste,

Railroad Line Maintenance, and Shipbuilding Dry Dock
12.0 - Pollutant Loading and Reduction Estimates

12-1

12.0 POLLUTANT LOADING AND REDUCTION ESTIMATES

This section describes EPA's estimation of industry pollutant loadings and

pollutant reductions for each MP&M technology option described in Section 9.0. The Agency

estimated pollutant loadings and reductions from MP&M sites to evaluate loadings to surface

waters and publicly owned treatment works (POTWs), and to assess the effectiveness of each

MP&M technology option in reducing these loadings. An assessment of the water-quality

impacts and benefits associated with the reduced pollutant loadings from MP&M facilities as

estimated in this section is presented in the report “Economic, Environmental, and Benefits

Assessment of the Proposed MP&M Rule.” This report is located in the public record for this

proposal. 

In estimating the pollutant loadings, EPA assumed that all nondetected pollutants

of concern are present at the detection limit. EPA did not use the same assumptions in all cases

when calculating limits (see Section 10.0). Throughout this section, the terms “sampling point”

and “sample” are used as defined below:

Sampling Point. A sampling point is the physical location at which samples are

collected. Example sampling points include a wastewater treatment influent

stream, an electroplating bath, or a cleaning rinse.

Sample. A sample is the unique volume of wastewater collected for analysis at a

sampling point. A sample can include several different aliquots collected for

analysis of multiple parameters. Each sample represents a unique period of time. 

EPA typically collected multiple samples from sampling points that represented

flowing wastestreams (e.g., wastewater treatment systems, rinses).

Figure 12-1 summarizes the steps used to estimate the MP&M pollutant loadings

and reductions for each technology option. These steps are described in Sections 12.1 and 12.2. 

Section 12.1 describes the calculation of pollutant concentrations for each unit operation. 

Section 12.2. presents the results of the raw, baseline, and post-compliance pollutant loading and

reduction calculations for the industry.
12.0 - Pollutant Loading and Reduction Estimates

12-2
12.0 - Pollutant Loading and Reduction Estimates

12-3

12.1 Estimation of Unit Operation Pollutant Concentrations

EPA used data collected during the MP&M sampling program to estimate

pollutant concentrations in wastewater streams from each of the MP&M unit operations reported

by questionnaire respondents as generating wastewater. EPA developed these estimates for each

pollutant of concern (see Section 7.0). These data are included in Sampling Episode Reports

(SERs) in the administrative record for this rulemaking. To develop the unit operation

concentrations, EPA calculated pollutant concentrations for each sampling point (Section 12.1.1),

then calculated the pollutant concentrations for each unit operation (Section 12.1.2).

The first step in estimating pollutant concentrations for each unit operation was to

identify unit operations for which pollutant concentrations depend on metal type. This was

important when transferring concentrations across unit operations (Section 12.1.2). EPA

reviewed the unit operation descriptions and analytical data to identify those unit operations for

which pollutant concentrations would be most dependent on metal type processed. While most

MP&M unit operations are somewhat dependent on metal type processed, EPA identified two

operations (and their associated rinses) for which pollutant concentrations are heavily dependent

on metal type: electroplating and electroless plating. In both of these operations and associated

rinses, pollutant concentrations depend on the metal type being applied in the operation. For

example, chromium electroplating operations and rinses contain higher concentrations of

chromium than other metals, while electroless nickel plating operations and rinses contain higher

concentrations of nickel than other metals.

12.1.1 Calculate Pollutant Concentrations for Each Sampling Point

EPA developed a pollutant profile (i.e., concentrations for each pollutant of

concern) for each sampling point. EPA used the following approach to calculate pollutant

concentrations for each sampling point:

C Average duplicate sample concentrations. As discussed in Section 4.0,

EPA collected duplicate samples at many sampling points as a quality

control measure. EPA averaged the concentrations for the original and

duplicate samples.

C Average multiple sample concentrations for each sampling point. At

sampling points representing flowing wastewater streams (e.g., rinses),

EPA typically collected multiple samples over time. EPA collected these

samples to account for variability over time of the discharges from these

streams. EPA averaged the concentrations for the samples collected on

multiple days at the same sampling point. For example, if EPA collected

three one-day composite samples for acid treatment rinsing at the same

sampling point, it averaged the concentrations for each pollutant on each

of the three days to estimate the pollutant concentration for the sampling

point.
12.0 - Pollutant Loading and Reduction Estimates

12-4

12.1.2 Estimate Pollutant Concentrations for Each Unit Operation

EPA estimated pollutant concentrations for each unit operation reported in the

MP&M detailed surveys. For electroplating and electroless plating operations, EPA estimated

concentrations for each unit operation and metal type combination reported in the surveys. EPA

used the following steps to estimate the pollutant concentrations:

C Identify all unit operations reported in the detailed surveys. EPA queried

the MP&M detailed survey database to identify all unit operations reported

as discharging wastewater, as well as all unit operation and metal type

combinations (based on applied metal) for electroplating and electroless

plating. EPA considered unit operations performed at facilities in the

Non-chromium Anodizing subcategory to be unique from unit operations

performed in other subcategories because the non-chromium anodizing

process primarily aluminum and perform a limited subset of unit

operations, as described in Section 6.2.4. Therefore, EPA developed

unique pollutant concentrations for operations performed at Nonchromium Anodizing facilities.

C Estimate pollutant concentrations for each unit operation for which

sampling analytical data are available. EPA averaged the pollutant

concentrations for each unit operation and each unit operation and metal

type combination (for electroplating and electroless plating) across sites. 

For example, EPA averaged the site-level pollutant concentrations for all

acid cleaning operations.

C Transfer data to unit operations for which sampling data are not

available. The final step in estimating unit operation pollutant

concentrations consisted of transferring data to unit operations for which

EPA did not collect sampling data. EPA transferred pollutant

concentrations from unit operations expected to have similar wastewater

characteristics based on process considerations, including the following:

the purpose of the unit operation (e.g., metal removal, contaminant

removal); the purpose of the process water use (e.g., contact cooling water,

cleaning solution, rinsewater); and the wastewater flow per unit of

production as reported in the MP&M surveys. Supporting documentation

for all data transfers of unit operation pollutant concentrations is contained

in the administrative record for this rulemaking.

12.2 Calculation of Industry Pollutant Loadings and Reductions

EPA estimated the pollutant loadings for each pollutant of concern for each

wastewater discharging unit operation at each model site (model site development is described in

Section 11.2). EPA estimated industry-wide raw wastewater pollutant loadings, baseline
12.0 - Pollutant Loading and Reduction Estimates

12-5

pollutant loadings, and option-specific loadings for each MP&M technology option as described

in Sections 12.2.1 through 12.2.3. EPA subtracted the option-specific post-compliance pollutant

loading estimates from the baseline loadings to estimate pollutant reductions for each option.

12.2.1 Industry Raw Wastewater Pollutant Loadings

Industry raw wastewater pollutant loadings represent the industry pollutant

loadings before removal by treatment technologies currently in place at MP&M sites. EPA used

the following steps to estimate the raw wastewater loadings:

C Estimate site-specific raw wastewater pollutant loadings. For each

wastewater discharging unit operation at each model site, EPA multiplied

the unit operation concentrations by its wastewater flow rate (as reported

in the questionnaire) to obtain a mass loading. EPA then summed the

loadings for each pollutant across all unit operations performed at each

model site to develop a site-specific raw wastewater pollutant loading.

C Estimate industry-wide raw wastewater pollutant loadings. EPA

multiplied the site-specific raw wastewater pollutant loadings for each

pollutant of concern by the corresponding site-specific statistically derived

weighting factors discussed in the report “Statistical Summary for the

MP&M Industry Surveys.” EPA summed the weighted loadings across all

sites in each subcategory to develop subcategory-specific raw wastewater

pollutant loadings. EPA also summed the weighted loadings across all

sites to develop industry-wide raw wastewater pollutant loadings.

Tables 12-1 and 12-2 present the results of the estimation for industry raw

wastewater annual pollutant loadings by subcategory for direct and indirect dischargers,

respectively. 

12.2.2 Industry Baseline Pollutant Loadings

Industry baseline pollutant loadings represent the industry pollutant loadings after

accounting for pollutant removals by technologies already in place at MP&M sites. Section 11.0

describes the assessment of technology in place for each model site. EPA used the following

steps to estimate the baseline pollutant loadings:

C Estimate site-specific baseline pollutant loadings. EPA performed a

baseline run of the MP&M Design and Cost Model to estimate sitespecific baseline pollutant loadings for each model site. The baseline run

used the technologies in place at each site rather than the MP&M

technology options. EPA estimated the site-specific baseline loadings as

the pollutants being discharged after the application of the treatment

technologies currently in place at model sites.
12.0 - Pollutant Loading and Reduction Estimates

12-6

C Estimate industry-wide baseline pollutant loadings. EPA multiplied the

site-specific baseline pollutant loadings for each pollutant of concern by

the corresponding site-specific statistically-derived weighting factors

discussed in the report “Statistical Summary for the MP&M Industry

Surveys.” EPA summed the weighted loadings across all sites in each

subcategory to develop subcategory-specific baseline pollutant loadings.

EPA also summed the weighted loadings across all sites to develop

industry-wide baseline pollutant loadings.

Tables 12-1 and 12-2 present the results of the estimation for industry baseline

pollutant loadings by subcategory for direct and indirect dischargers, respectively. 

12.2.3 Option-Specific Industry Pollutant Loadings and Pollutant Reductions

Option-specific pollutant loadings (i.e., post-compliance pollutant loadings for

each technology option) represent the total industry pollutant loadings after the application of

each MP&M technology option. Option-specific pollutant reductions represent the total industry

pollutant removals for each technology option. EPA estimated option-specific loadings and

reductions as follows:

C Estimate site-specific, option-specific pollutant loadings. EPA used the

MP&M Design and Cost Model (see Section 11.0) to estimate pollutant

loadings for each site for each technology option.

C Estimate site-specific, option-specific pollutant removals. EPA estimated

the option-specific pollutant removals as the difference between the sitespecific baseline pollutant loadings and the option-specific pollutant

loadings. For indirect dischargers, EPA then reduced the site-specific,

option-specific pollutant removals by their corresponding POTW percent

removal (see Table 12-3) to account for treatment that will occur at the

POTW.

C Estimate industry-wide, option-specific pollutant loadings and removals.

For each option, EPA multiplied the site-specific pollutant loadings and

removals (accounting for POTW removals for indirect dischargers) for

each pollutant of concern by the corresponding site-specific statisticallyderived weighting factors discussed in the report “Statistical Summary for

the MP&M Industry Surveys.” EPA summed the weighted loadings and

removals across all sites in each subcategory to develop subcategoryspecific pollutant loadings and removals. EPA also summed the weighted

loadings and removals across all sites to develop industry-wide pollutant

loadings and reductions.
12.0 - Pollutant Loading and Reduction Estimates

12-7

Tables 12-2 and 12-3 present the estimated Selected Option pollutant loadings by

subcategory for direct and indirect dischargers, respectively. Tables 12-4 and 12-5 present the

estimated pollutant removals by the Selected Option for direct and indirect dischargers,

respectively. Tables 12-6 through 12-20 present the top pollutants removed (in toxic pound

equivalents) by the Selected Option by subcategory for direct and indirect dischargers.
12-8

12.0 - Pollutant Loading and Reduction Estimates

Table 12-1

Summary of Annual Pollutant Loadings for MP&M Direct Dischargers by Subcategory

Subcategory

Total

No. of

Sites

Industry Raw Wastewater Pollutant Loadings (a) Baseline Pollutant Loadings (b) Selected Option Pollutant Loadings (c)

(lbs-eq/yr)

(lbs/yr) 

(lbs-eq/yr)

(lbs/yr) 

(lbs-eq/yr)

(lbs/yr) 

Priority &

Nonconventional

Metals/

Organics(d)

TSS/Oil and

Grease

(as HEM)

Priority &

Nonconventional

Metals/

Organics(d)

TSS/Oil

and Grease

(as HEM)

Priority &

Nonconventional

Metals/

Organics(d)

TSS/Oil

and Grease

(as HEM)

General Metals 3,784 6,521,910 46,976,587 115,775,867 1,248,018 10,653,897 19,050,051 133,429 1,420,008 1,161,143

Metal Finishing

Job Shops 16 34,622 151,584 261,057 15,672 56,102 38,319 1,608 11,992 10,776

Non-Chromium

Anodizing (e) - - - - - - - - - -

Printed Wiring

Board 12 249,276 1,167,185 729,629 59,340 278,370 362,431 11,922 83,015 73,770

Steel Forming and

Finishing 43 3,327,437 23,205,748 11,374,652 124,972 941,572 1,276,363 208,877 630,756 38,891,453

Oily Wastes 912 81,407 1,639,048 12,343,318 21,060 730,372 1,378,666 22,535 661,310 356,912

Railroad Line

Maintenance (f) 34 2,145 187,605 990,500 1,128 55,611 70,158 1,267 179,157 16,021

Shipbuilding Dry

Dock 6 27,903 3,393,475 8,946,211 1,815 94,772 8,515,131 1,896 95,936 102,502

Source: MP&M pollutant loadings.

(a) These raw loads do not reflect treatment currently in place.

(b) These baseline loads reflect treatment currently in place.

(c) These loads reflect the load after the implementation of the MP&M technology basis for each subcategory.

(d) Does not include sodium, calcium, total dissolved solids, and potassium.

(e) EPA’s data collection efforts did not identify any direct discharging non-chromium anodizing facilities.

(f) The baseline and the Selected Option pollutant loadings for BOD5 for Railroad Line Maintenance is 59,814 and 57,150 lbs/yr, respectively.
12-9

12.0 - Pollutant Loading and Reduction Estimates

Table 12-2

Summary of Annual Pollutant Loadings for MP&M Indirect Dischargers by Subcategory(a)

Subcategory

Total

No. of

Sites

Industry Raw Wastewater Pollutant Loadings (b) Baseline Pollutant Loadings (c) Selected Option Pollutant Loadings (d,e)

(lbs-eq/yr)

(lbs/yr) 

(lbs-eq/yr)

(lbs/yr) 

(lbs-eq/yr)

(lbs/yr) 

Priority &

Nonconventional

Metals/ Organics

(f)

TSS/Oil and

Grease

(as HEM)

Priority &

Nonconventional

Metals/ Organics

(f)

TSS/Oil

and Grease

(as HEM)

Priority &

Nonconventional

Metals/ Organics

(f)

TSS/Oil and

Grease

(as HEM)

General Metals 26,195 116,275,842 555,129,426 737,700,419 23,804,767 155,478,167 398,844,708 1,241,465 11,732,601 11,082,451

Metal Finishing

Job Shops 1,515 20,417,884 38,428,372 15,780,889 5,598,845 12,741,874 10,406,023 118,988 1,015,185 813,455

Non-Chromium

Anodizing 191 122,359 869,757 1,718,224 117,647 808,018 1,473,802 NR NR NR

Printed Wiring

Board 621 5,732,973 21,773,732 26,175,775 2,727,103 9,103,518 20,019,186 149,959 1,226,487 941,657

Steel Forming and

Finishing 111 1,248,907 9,120,891 6,328,042 400,524 2,667,746 1,045,957 104,606 336,249 22,531,113

Oily Wastes 28,514 1,002,116 17,206,229 75,298,418 496,626 13,396,099 24,366,355 506,597 3,333,132 4,822,848

Railroad Line

Maintenance 799 3,794 40,084 10,463,731 1,712 14,759 71,136 NR NR NR

Shipbuilding Dry

Dock 6 397 38,542 13,482 257 25,984 5,356 NR NR NR

Source: MP&M pollutant loadings.

NR - Not regulated. EPA is not proposing to regulate these sites under the MP&M rule.

(a) These loads do not reflect removals by publicly owned treatment works (see Table 12-4 for incorporation of POTW removals).

(b) These raw loads do not reflect treatment currently in place.

(c) These baseline loads reflect treatment currently in place.

(d) These loads include only those for the regulated sites; this accounts for 3,056 General Metals facilities discharging greater than 1 MGY and 226 Oily Wastes

facilities discharging greater than 2 MGY.

(e) These loads reflect the load after the implementation of the MP&M technology basis for each subcategory.

(f) Does not include sodium, calcium, total dissolved solids, and potassium.
12.0 - Pollutant Loading and Reduction Estimates

12-10

Table 12-3 

Publicly Owned Treatment Works (POTW) Removal Percents For Each

MP&M Pollutants of Concern

Chemical Name

POTW

Removal

Percent Sourcea-c

1,1,1-Trichloroethane 90.45 a

1,1-Dichloroethane 70 a

1,1-Dichloroethene 77.51 c

1,4-Dioxane 45.8 b

1-Bromo-2-Chlorobenzene 77.32 c

1-Bromo-3-Chlorobenzene 77.32 c

1-Methylfluorene 84.55 b

1-Methylphenanthrene 84.55 b

2,4-Dimethylphenol 77.51 c

2,4-Dinitrophenol 77.51 c

2,6-Dinitrotoluene 77.51 c

2-Butanone 96.6 b

2-Hexanone 77.32 c

2-Isopropylnaphthalene 77.32 c

2-Methylnaphthalene 28 b

2-Nitrophenol 26.83 a

2-Propanone 83.75 b

3,6-Dimethylphenanthrene 84.55 b

4-Chloro-3-Methylphenol 63 b

4-Methyl-2-Pentanone 87.87 b

4-Nitrophenol 77.51 c

Acenaphthene 98.29 a

Acetophenone 95.34 b

Acrolein 77.51 c

Alpha-Terpineol 94.4 b

Aluminum 91.36 a

Amenable Cyanide 57.41 c

Ammonia As Nitrogen 38.94 a

Aniline 93.41 b
Table 12-3 (Continued)

12.0 - Pollutant Loading and Reduction Estimates

Chemical Name

POTW

Removal

Percent Sourcea-c

12-11

Anthracene 77.51 c

Antimony 66.78 a

Arsenic 65.77 a

Barium 15.98 a

Benzoic Acid 80.5 b

Benzyl Alcohol 78 b

Beryllium 71.66 c

Biphenyl 96.28 b

Bis(2-Ethylhexyl) Phthalate 59.78 a

Bod 5-Day (Carbonaceous) 89.12 a

Boron 30.42 a

Butyl Benzyl Phthalate 81.65 a

Cadmium 90.05 a

Calcium 8.54 a

Carbon Disulfide 84 b

Chemical Oxygen Demand (COD) 81.3 a

Chloride 57.41 c

Chlorobenzene 96.37 a

Chloroethane 77.51 c

Chloroform 73.44 a

Chromium 80.33 a

Cobalt 6.11 a

Copper 84.2 a

Cyanide 70.44 a

Di-N-Butyl Phthalate 84.66 a

Di-N-Octyl Phthalate 68.43 a

Dibenzofuran 77.32 c

Dibenzothiophene 84.68 b

Dimethyl Phthalate 77.51 c

Diphenyl Ether 77.32 c

Diphenylamine 77.32 c

Ethylbenzene 93.79 a
Table 12-3 (Continued)

12.0 - Pollutant Loading and Reduction Estimates

Chemical Name

POTW

Removal

Percent Sourcea-c

12-12

Fluoranthene 42.46 a

Fluorene 69.85 a

Fluoride 61.35

Gold 32.52 c

Hexanoic Acid 84 b

Hexavalent Chromium 57.41 c

Iron 81.99 a

Isobutyl Alcohol 28 b

Isophorone 77.51 c

Lead 77.45 a

M+P Xylene 77.32 c

M-Xylene 95.07 b

Magnesium 14.14 a

Manganese 35.51 a

Mercury 71.66 c

Methyl Methacrylate 99.96 b

Methylene Chloride 54.28 a

Molybdenum 18.93 a

N,N-Dimethylformamide 87 b

N-Decane 9 b

N-Docosane 88 b

N-Dodecane 95.05 b

N-Eicosane 92.4 b

N-Hexacosane 71.11 b

N-Hexadecane 71.11 b

N-Nitrosodimethylamine 77.51 c

N-Nitrosodiphenylamine 90.11 b

N-Nitrosopiperidine 77.32 c

N-Octacosane 71.11 b

N-Octadecane 71.11 b

N-Tetracosane 71.11 b

N-Tetradecane 71.11 b
Table 12-3 (Continued)

12.0 - Pollutant Loading and Reduction Estimates

Chemical Name

POTW

Removal

Percent Sourcea-c

12-13

N-Triacontane 77.32 c

Naphthalene 94.69 a

Nickel 51.44 a

O+P Xylene 65.4 b

O-Cresol 52.5 b

O-Xylene 77.32 c

Oil And Grease (As HEM) 86.08 a

P-Cresol 71.67 b

P-Cymene 99.79 b

Phenanthrene 94.89 a

Phenol 95.25 a

Phosphorus 32.52 c

Pyrene 83.9 b

Pyridine 95.4 b

Selenium 34.33 b

Silver 88.28 a

Sodium 2.69 a

Styrene 93.65 b

Sulfate 84.61 b

Tetrachloroethene 84.61 a

Thallium 71.66 c

Tin 42 a

Titanium 91.82 a

Toluene 96.18 a

Total Dissolved Solids 8 b

Total Kjeldahl Nitrogen 57.41 c

Total Organic Carbon (TOC) 70.28 a

Total Petroleum Hydrocarbons (As SGT-HEM) 57.41 c

Total Phosphorus 57.41 c

Total Recoverable Phenolics 57.41 c

Total Sulfide 57.41 c

Total Suspended Solids 89.55 a
Table 12-3 (Continued)

12.0 - Pollutant Loading and Reduction Estimates

Chemical Name

POTW

Removal

Percent Sourcea-c

12-14

Trichloroethene 77.51 c

Trichlorofluoromethane 77.32 c

Tripropyleneglycol Methyl Ether 52.4 b

Vanadium 9.51 a

Weak-Acid Dissociable Cyanide 57.41 c

Yttrium 32.52 c

Zinc 79.14 a

Note: See public record for further detail for the sources. 

a

 November 5, 1999 Updated 50-POTW Study. Influent Concentration 10xML, 5xML, then 20 ppb.

b

 RREL Database. Compiled for the CWT effluent guideline or the 1995 Phase I Proposal.

c

 Average POTW removals calculated by classification code from sources a and b. 
12-15

12.0 - Pollutant Loading and Reduction Estimates

Table 12-4

Summary of Annual Pollutant Reductions for MP&M Direct Dischargers by Subcategory (a,b)

Subcategory

Total No. of

Regulated

Sites

Baseline Pollutant Loadings Pollutant Removals by Selected Option

% Reduction from

lb-eq/yr lbs/yr (c) lb-eq/yr lbs/yr (c) Baseline (lb-eq/yr)

General Metals 3,795 1,248,018 29,703,949 1,123,797 27,224,783 90.0%

Metal Finishing Job Shops 16 15,672 94,422 14,377 71,766 91.7%

Non-Chromium Anodizer NA (d) - - - - -

Printed Wiring Board 12 59,340 640,801 48,366 485,395 81.5%

Steel Forming and Finishing 43 124,972 2,217,935 85,070 1,448,450 68.1%

Oily Wastes 912 21,060 2,109,039 9,899 1,441,671 47.0%

Railroad Line Maintenance 34 1,128 125,770 154 57,538 13.6%

Shipbuilding Dry Dock 6 1,815 8,609,903 111 8,453,293 6.1%

Source: MP&M pollutant loadings.

(a) Pollutant loadings and removal estimates presented in this table will not equate with those presented in the Cost-Effectiveness Analysis and the EEBA. The

estimates in those documents do not include pollutant loadings from facilities that are projected to close in the baseline.

(b) See Tables 12-6 through 12-12 for pollutant-specific removals by subcategory.

(c) Does not include sodium, calcium, total dissolved solids, chemical oxygen demand, and potassium.

(d) EPA’s data collection efforts did not identify any direct discharging non-chromium anodizing facilities.
12-16

12.0 - Pollutant Loading and Reduction Estimates

Table 12-5

Summary of Annual Pollutant Reductions for MP&M Indirect Dischargers by Subcategory (a,b)

Subcategory

Total No. of

Regulated

Sites

Baseline Pollutant Loadings Pollutant Removals by Selected Option (c)

% Reduction from

lb-eq/yr lbs/yr (d) lb-eq/yr lbs/yr (d) Baseline (lb-eq/yr)

General Metals 3,795 21,859,748 508,792,176 5,513,689 75,222,259 25.2%

Metal Finishing Job Shops 16 5,598,845 23,147,897 1,626,502 4,595,928 29.1%

Non-Chromium Anodizer NA (e) - - - - -

Printed Wiring Board 12 2,727,103 29,122,704 920,640 5,128,256 33.8%

Steel Forming and Finishing 43 400,524 3,713,703 115,624 731,264 28.9%

Oily Wastes 912 257,894 12,942,097 36,866 1,471,328 14.3%

Railroad Line Maintenance NA (4) - - - - -

Shipbuilding Dry Dock NA (4) - - - - -

Source: MP&M pollutant loadings.

(a) Pollutant loadings and removal estimates presented in this table will not equate with those presented in the Cost-Effectiveness Analysis and the EEBA. The

estimates in those documents do not include pollutant loadings from facilities that are projected to close in the baseline.

(b) See Tables 12-13 through 12-20 for pollutant-specific removals for each subcategory.

(c) These removals account for removals by publicly owned treatment works for each pollutant for the Selected Option.

(d) Does not include sodium, calcium, total dissolved solids, chemical oxygen demand and potassium.

(e) EPA is not proposing pretreatment standards for these subcategories.
12.0 - Pollutant Loading and Reduction Estimates

12-17

Table 12-6

Top Pollutants Removed by Proposed Option for

General Metals Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TOTAL SULFIDE 421,356 150,484

TIN 251,019 836,729

COPPER 242,366 384,707

CYANIDE 202,008 183,644

SILVER 119,080 7,442

BORON 82,034 455,746

LEAD 62,838 28,563

MOLYBDENUM 25,118 125,590

ALUMINUM 19,104 298,496

ZINC 15,234 324,130

ANTHRACENE 14,466 5,786

NICKEL 14,075 127,953

CHROMIUM 10,602 139,495

CADMIUM 10,317 3,968

HEXAVALENT CHROMIUM 8,309 16,293

MANGANESE 7,814 111,630

ANILINE 7,640 5,457

IRON 5,338 953,206

FLUORANTHENE 4,643 5,804

FLUORIDE 4,496 128,464

FLUORENE 4,051 5,787

BIS(2-ETHYLHEXYL) PHTHALATE 3,080 32,421

ACROLEIN 3,076 3,171

N-NITROSODIMETHYLAMINE 1,771 25,302

PHENANTHRENE 1,703 5,873

3,6-DIMETHYLPHENANTHRENE 1,596 5,910

CARBON DISULFIDE 1,482 529

DI-N-OCTYL PHTHALATE 1,272 5,781

DIBENZOFURAN 1,091 5,455
12.0 - Pollutant Loading and Reduction Estimates

Table 12-6 (Continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-18

BENZOIC ACID 997 3,019,908

SELENIUM 910 827

AMMONIA AS NITROGEN 817 326,833

2,6-DINITROTOLUENE 645 6,449

PYRENE 637 5,786

N-TETRADECANE 619 143,925

1-METHYLPHENANTHRENE 610 6,102

ARSENIC 543 155

Source: MP&M pollutant loadings.
12-19

12.0 - Pollutant Loading and Reduction Estimates

Table 12-7

Top Pollutants Removed by Proposed Option for Metal Finishing

Job Shops Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

CYANIDE 6,257 5,688

TIN 3,508 11,694

COPPER 2,496 3,962

TOTAL SULFIDE 2,133 762

NICKEL 585 5,316

BORON 356 1,976

CHROMIUM 246 3,239

LEAD 179 81

ANTHRACENE 157 63

ZINC 94 2,008

ANILINE 88 63

HEXAVALENT CHROMIUM 77 150

FLUORANTHENE 50 63

FLUORENE 44 63

ACROLEIN 39 40

SILVER 37 2

MOLYBDENUM 35 174

ALUMINUM 30 475

PHENANTHRENE 18 63

3,6-DIMETHYLPHENANTHRENE 17 64

IRON 17 3,038

DI-N-OCTYL PHTHALATE 14 63

DIBENZOFURAN 13 63

MANGANESE 11 154

CADMIUM 9 4

FLUORIDE 8 215

BIS(2-ETHYLHEXYL) PHTHALATE 7 74

N-NITROSODIMETHYLAMINE 7 100

PYRENE 7 63

AMMONIA AS NITROGEN 7 2,756
12.0 - Pollutant Loading and Reduction Estimates

Table 12-7 (Continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-20

2,6-DINITROTOLUENE 6 65

1-METHYLPHENANTHRENE 6 65

2-METHYLNAPHTHALENE 5 61

2-ISOPROPYLNAPHTHALENE 5 66

N-NITROSODIPHENYLAMINE 4 102

1-METHYLFLUORENE 3 62

DIBENZOTHIOPHENE 3 63

Source: MP&M pollutant loadings.
12.0 - Pollutant Loading and Reduction Estimates

12-21

Table 12-8

Top Pollutants Removed by Proposed Option for Printed

Wiring Board Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TIN 23,886 79,619

TOTAL SULFIDE 16,121 5,757

COPPER 14,562 23,114

CARBON DISULFIDE 3,311 1,183

NICKEL 2,155 19,593

CYANIDE 1,487 1,351

LEAD 1,013 460

BORON 623 3,460

ZINC 263 5,594

ALUMINUM 208 3,244

IRON 176 31,420

MOLYBDENUM 155 774

CHROMIUM 146 1,926

MANGANESE 76 1,083

SILVER 57 4

ACROLEIN 56 57

ANTHRACENE 43 17

AMMONIA AS NITROGEN 43 17,090

FLUORIDE 30 870

ARSENIC 26 7

ANILINE 24 17

FLUORANTHENE 14 17

FLUORENE 12 17

TITANIUM 10 335

COBALT 7 59

N-NITROSODIMETHYLAMINE 6 88

BENZOIC ACID 6 17,689

PHENANTHRENE 5 17

BIS(2-ETHYLHEXYL) PHTHALATE 5 50

3,6-DIMETHYLPHENANTHRENE 5 17

DI-N-OCTYL PHTHALATE 4 17

DIBENZOFURAN 3 17

1,1-DICHLOROETHENE 3 16

SULFATE 3 474,868

Source: MP&M pollutant loadings.
12-22

12.0 - Pollutant Loading and Reduction Estimates

Table 12-9

Top Pollutants Removed by Proposed Option for Steel Forming

and Finishing Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TOTAL SULFIDE 252,728 90,260

TIN 29,991 99,970

COPPER 23,848 37,854

BORON 11,125 61,804

LEAD 4,515 2,052

NICKEL 2,365 21,501

SILVER 2,209 138

ALUMINUM 1,899 29,672

CYANIDE 1,228 1,116

CHROMIUM 1,117 14,701

FLUORIDE 924 26,392

ACROLEIN 911 939

ANTHRACENE 864 346

ZINC 843 17,935

CARBON DISULFIDE 575 205

ANILINE 438 313

MOLYBDENUM 298 1,490

MANGANESE 293 4,193

FLUORANTHENE 273 342

ARSENIC 250 71

FLUORENE 239 342

VANADIUM 214 346

SELENIUM 172 156

AMMONIA AS NITROGEN 160 64,119

IRON 132 23,646

CHLORIDE 119 4,939,545

N-NITROSODIMETHYLAMINE 111 1,588

3,6-DIMETHYLPHENANTHRENE 107 398
12.0 - Pollutant Loading and Reduction Estimates

Table 12-9 (Continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-23

MERCURY 103 1

PHENANTHRENE 103 353

BIS(2-ETHYLHEXYL) PHTHALATE 94 984

DI-N-OCTYL PHTHALATE 75 341

DIBENZOFURAN 63 313

MAGNESIUM 59 67,510

HEXAVALENT CHROMIUM 51 100

2,6-DINITROTOLUENE 50 500

Source: MP&M pollutant loadings.
12-24

12.0 - Pollutant Loading and Reduction Estimates

Table 12-10

Top Pollutants Removed by Proposed Option for

Oily Wastes Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TOTAL SULFIDE 6,141 2,193

LEAD 1,973 897

BORON 1,556 8,643

COPPER 1,160 1,842

MOLYBDENUM 865 4,325

SILVER 823 51

CADMIUM 709 273

ANTHRACENE 646 258

ALUMINUM 312 4,870

ANILINE 288 206

FLUORANTHENE 207 259

IRON 196 34,979

FLUORENE 181 258

ZINC 170 3,607

PHENANTHRENE 77 266

ACROLEIN 64 66

3,6-DIMETHYLPHENANTHRENE 63 235

DI-N-OCTYL PHTHALATE 63 285

N-NITROSODIMETHYLAMINE 56 800

DIBENZOFURAN 41 206

NICKEL 36 325

BENZOIC ACID 36 108,125

BIS(2-ETHYLHEXYL) PHTHALATE 35 372

2,6-DINITROTOLUENE 29 289

PYRENE 28 258

TIN 21 71

ARSENIC 20 6

2-ISOPROPYLNAPHTHALENE 20 271

MAGNESIUM 18 20,363

FLUORIDE 17 487

N-NITROSODIPHENYLAMINE 17 421

2-METHYLNAPHTHALENE 16 202

CHROMIUM 16 207

1-METHYLPHENANTHRENE 13 127

MANGANESE 12 170

Source: MP&M pollutant loadings.
12-25

12.0 - Pollutant Loading and Reduction Estimates

Table 12-11

Top Pollutants Removed by Proposed Option for Railroad 

Line Maintenance Direct Dischargers

Pollutant Name Toxic Pound Equivalents

Removed (lb-eq/yr)

Pounds Removed (lb/yr)

BORON 87 485

LEAD 24 11

TOTAL SULFIDE 21 7.332

ALUMINUM 9.036 141

SILVER 7.803 0.488

TIN 5.876 20

CADMIUM 4.975 1.914

COPPER 4.541 7.208

IRON 1.746 312

ZINC 1.551 33

MANGANESE 1.396 20

ANTHRACENE 0.909 0.364

ANILINE 0.868 0.620

MOLYBDENUM 0.490 2.451

CHROMIUM 0.490 6.443

NICKEL 0.296 2.695

FLUORANTHENE 0.291 0.364

N-NITROSODIMETHYLAMINE 0.279 3.982

FLUORENE 0.255 0.364

TITANIUM 0.197 6.777

3,6-DIMETHYLPHENANTHRENE 0.181 0.672

2-METHYLNAPHTHALENE 0.128 1.598

DIBENZOFURAN 0.124 0.620

PHENANTHRENE 0.107 0.368

1-METHYLPHENANTHRENE 0.100 1.003

BIS(2-ETHYLHEXYL) PHTHALATE 0.082 0.860

VANADIUM 0.068 0.110

2-ISOPROPYLNAPHTHALENE 0.058 0.799

N-NITROSODIPHENYLAMINE 0.051 1.268

DI-N-OCTYL PHTHALATE 0.050 0.228

Source: MP&M pollutant loadings.
12-26

12.0 - Pollutant Loading and Reduction Estimates

Table 12-12

Top Pollutants Removed by Proposed Option for Shipbuilding Dry Dock

Direct Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

CHROMIUM 63 832

MANGANESE 36 515

NICKEL 7.71 70

MOLYBDENUM 3.53 17.64

BENZOIC ACID 0.235 712

1-METHYLPHENANTHRENE 0.041 0.409

Source: MP&M pollutant loadings.
12.0 - Pollutant Loading and Reduction Estimates

12-27

Table 12-13

Top Pollutants Removed by Proposed Option for

General Metals Indirect Dischargersa

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

COPPER 1,792,625 2,845,436

TOTAL SULFIDE 1,383,215 494,006

TIN 1,212,529 4,041,764

BORON 559,185 3,106,581

LEAD 527,231 239,651

NICKEL 315,515 2,868,315

CYANIDE 312,109 283,735

MOLYBDENUM 241,330 1,206,652

MANGANESE 229,618 3,280,260

FLUORIDE 126,412 3,611,778

VANADIUM 57,919 93,417

ZINC 44,761 952,356

CHROMIUM 42,165 554,801

ALUMINUM 40,314 629,903

IRON 34,230 6,112,555

SILVER 26,973 1,686

ANTHRACENE 11,743 4,697

CADMIUM 10,250 3,942

AMMONIA AS NITROGEN 10,126 4,050,566

FLUORANTHENE 9,817 12,271

ARSENIC 4,871 1,392

COBALT 4,444 40,402

FLUORENE 4,423 6,319

SELENIUM 4,179 3,800

HEXAVALENT CHROMIUM 3,380 6,628

ACROLEIN 2,665 2,748

TITANIUM 2,577 88,874

BIS(2-ETHYLHEXYL) PHTHALATE 2,531 26,643

BENZOIC ACID 2,180 6,607,285

ANILINE 1,792 1,280

MAGNESIUM 1,787 2,053,495

CARBON DISULFIDE 1,714 612
12.0 - Pollutant Loading and Reduction Estimates

Table 12-13 (continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-28

CHLORIDE 1,594 66,435,600

DI-N-OCTYL PHTHALATE 1,481 6,731

N-NITROSODIMETHYLAMINE 1,447 20,669

2-METHYLNAPHTHALENE 1,290 16,126

3,6-DIMETHYLPHENANTHRENE 954 3,532

THALLIUM 923 923

DIBENZOFURAN 872 4,358

2,6-DINITROTOLUENE 569 5,693

Source: MP&M pollutant loadings.

(a) The Proposed Option for General Metals indirect dischargers includes only those facilities that discharge greater

than 1 MGY of process wastewater.
12-29

12.0 - Pollutant Loading and Reduction Estimates

Table 12-14

Top Pollutants Removed by Proposed Option for Metal Finishing

Job Shops Indirect Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

CYANIDE 1,113,405 1,012,187

TIN 242,337 807,789

COPPER 148,476 235,676

TOTAL SULFIDE 122,061 43,593

BORON 44,719 248,436

NICKEL 25,840 234,910

LEAD 11,537 5,244

CHROMIUM 7,741 101,853

MANGANESE 7,186 102,654

FLUORIDE 5,055 144,432

SILVER 4,598 287

ZINC 4,149 88,282

CADMIUM 3,681 1,416

IRON 2,930 523,164

MOLYBDENUM 2,700 13,498

CARBON DISULFIDE 2,647 945

HEXAVALENT CHROMIUM 1,266 2,483

ALUMINUM 1,219 19,053

AMMONIA AS NITROGEN 964 385,723

VANADIUM 605 977

ANTHRACENE 440 176

FLUORANTHENE 360 450

ARSENIC 277 79

ACROLEIN 272 280

THALLIUM 185 185

FLUORENE 165 236

COBALT 164 1,488

CHLORIDE 150 6,256,880

SELENIUM 92 84

BIS(2-ETHYLHEXYL) PHTHALATE 81 851
12.0 - Pollutant Loading and Reduction Estimates

Table 12-14 (Continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-30

TITANIUM 78 2,676

ANILINE 71 51

MAGNESIUM 59 68,292

N-NITROSODIMETHYLAMINE 58 832

2-METHYLNAPHTHALENE 56 695

DI-N-OCTYL PHTHALATE 54 247

Source: MP&M pollutant loadings.
12-31

12.0 - Pollutant Loading and Reduction Estimates

Table 12-15

Top Pollutants Removed by Option 2 for Non-Chromium 

Anodizing Indirect Dischargersa

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

NICKEL 3,218 29,251

MANGANESE 2,393 34,185

BORON 1,917 10,652

TOTAL SULFIDE 1,028 367

ZINC 966 20,552

FLUORIDE 350 9,999

ALUMINUM 267 4,165

COPPER 71 112

CADMIUM 44 17

TIN 39 129

IRON 22 3,868

ANTHRACENE 15 6

FLUORANTHENE 12 15

CHROMIUM 9 122

MAGNESIUM 6 6,833

FLUORENE 5 8

ACROLEIN 5 5

Source: MP&M pollutant loadings.

(a) EPA is not proposing pretreatment standards for all indirect discharging facilities in the Non-Chromium

Anodizing subcategory. Therefore, the removals are presented only for informational purposes.
12-32

12.0 - Pollutant Loading and Reduction Estimates

Table 12-16

Top Pollutants Removed by Proposed Option for Printed

Wiring Board Indirect Dischargers

Pollutant Name

Toxic Pound Equivalents Removed

(lb-eq/yr) Pounds Removed (lb/yr)

TIN 468,973 1,563,245

TOTAL SULFIDE 257,025 91,795

CYANIDE 253,216 230,197

COPPER 104,235 165,453

NICKEL 39,774 361,578

LEAD 23,781 10,810

BORON 14,805 82,250

MANGANESE 4,067 58,107

CHROMIUM 2,374 31,243

ZINC 2,090 44,460

IRON 1,732 309,307

FLUORIDE 1,568 44,797

CARBON DISULFIDE 1,510 539

ALUMINUM 1,164 18,187

AMMONIA AS NITROGEN 1,065 425,901

SILVER 740 46

MOLYBDENUM 701 3,507

COBALT 247 2,247

ANTHRACENE 245 98

FLUORANTHENE 200 250

ACROLEIN 112 116

FLUORENE 92 131

VANADIUM 69 111

CADMIUM 66 25

SELENIUM 63 57

TITANIUM 48 1,664

ANILINE 40 28

CHLORIDE 36 1,515,053

N-NITROSODIMETHYLAMINE 34 489

DI-N-OCTYL PHTHALATE 30 137

HEXAVALENT CHROMIUM 26 52

BIS(2-ETHYLHEXYL) PHTHALATE 24 252

2-METHYLNAPHTHALENE 23 286

MAGNESIUM 21 24,041

Source: MP&M pollutant loadings.
12-33

12.0 - Pollutant Loading and Reduction Estimates

Table 12-17

Top Pollutants Removed by Proposed Option for Steel Forming

and Finishing Indirect Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TIN 68,545 228,482

TOTAL SULFIDE 53,018 18,935

COPPER 37,074 58,848

BORON 4,355 24,193

FLUORIDE 3,093 88,365

IRON 1,425 254,463

NICKEL 1,229 11,174

ZINC 522 11,104

AMMONIA AS NITROGEN 359 143,769

VANADIUM 295 476

CHROMIUM 290 3,812

ANTHRACENE 270 108

LEAD 257 117

MANGANESE 250 3,565

FLUORANTHENE 221 276

CYANIDE 199 181

CHLORIDE 160 6,684,396

MOLYBDENUM 118 591

FLUORENE 101 145

ALUMINUM 72 1,122

TITANIUM 42 1,436

DI-N-OCTYL PHTHALATE 33 152

ANILINE 28 20

ACROLEIN 28 29

SELENIUM 26 24

SILVER 25 2

ARSENIC 22 6

COBALT 21 187

BIS(2-ETHYLHEXYL) PHTHALATE 19 202

2-METHYLNAPHTHALENE 17 216
12.0 - Pollutant Loading and Reduction Estimates

Table 12-17 (Continued)

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

12-34

CADMIUM 16 6

MAGNESIUM 15 16,829

DIBENZOFURAN 14 69

3,6-DIMETHYLPHENANTHRENE 13 48

2,6-DINITROTOLUENE 11 111

N-NITROSODIMETHYLAMINE 11 158

.

Source: MP&M pollutant loadings.
12-35

12.0 - Pollutant Loading and Reduction Estimates

Table 12-18

Top Pollutants Removed by Proposed Option for 

Oily Wastes Indirect Dischargersa

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

TOTAL SULFIDE 40,158 14,342

MOLYBDENUM 35,485 177,425

BENZOIC ACID 366 1,108,465

LEAD 166 75

COPPER 137 217

ANTHRACENE 117 47

FLUORANTHENE 96 120

CADMIUM 93 36

SELENIUM 89 81

FLUORENE 44 63

ARSENIC 34 10

ZINC 33 710

NICKEL 26 236

IRON 25 4,411

BIS(2-ETHYLHEXYL) PHTHALATE 20 216

DI-N-OCTYL PHTHALATE 14 66

2-METHYLNAPHTHALENE 14 178

ANILINE 14 10

ACROLEIN 10 11

ALUMINUM 8 119

MAGNESIUM 7 7,949

3,6-DIMETHYLPHENANTHRENE 7 26

DIBENZOFURAN 7 33

CHROMIUM 6 82

N-NITROSODIMETHYLAMINE 6 86

2,6-DINITROTOLUENE 5 54

N-TETRADECANE 5 1,204

PYRENE 4 34

2-ISOPROPYLNAPHTHALENE 3 47

PHENANTHRENE 3 11

1-METHYLPHENANTHRENE 3 27

MANGANESE 2 30

Source: MP&M pollutant loadings.

(a) The Proposed Option for Oily Wastes indirect dischargers includes only those facilities that discharge greater

than 2 MGY of process wastewater. The pollutant removals on this table reflect those associated with the Selected

Option.
12-36

12.0 - Pollutant Loading and Reduction Estimates

Table 12-19

Top Pollutants Removed by Option 10 for Railroad

Line Maintenance Indirect Dischargers

Pollutant Name

Toxic Pound Equivalents

Removed (lb-eq/yr) Pounds Removed (lb/yr)

LEAD 2.67 1.21

MANGANESE 2.13 30.4

ANTHRACENE 2.13 0.85

FLUORANTHENE 1.74 2.18

TIN 1.39 4.62

COPPER 1.00 1.59

BORON 0.801 4.45

FLUORENE 0.798 1.14

FLUORIDE 0.527 15.1

CADMIUM 0.427 0.164

SILVER 0.299 0.019

SELENIUM 0.274 0.249

DI-N-OCTYL PHTHALATE 0.221 1.00

ALUMINUM 0.216 3.38

MERCURY 0.214 0.002

ANILINE 0.208 0.149

ZINC 0.192 4.09

MOLYBDENUM 0.190 0.950

VANADIUM 0.184 0.296

2-METHYLNAPHTHALENE 0.147 1.84

CARBON DISULFIDE 0.140 0.050

NICKEL 0.124 1.13

IRON 0.120 21.4

BIS(2-ETHYLHEXYL) PHTHALATE 0.115 1.21

ARSENIC 0.114 0.032

HEXAVALENT CHROMIUM 0.106 0.208

DIBENZOFURAN 0.102 0.512

3,6-DIMETHYLPHENANTHRENE 0.094 0.346

COBALT 0.086 0.780

2,6-DINITROTOLUENE 0.085 0.850

N-NITROSODIMETHYLAMINE 0.073 1.05

PYRENE 0.067 0.609

ACROLEIN 0.066 0.068

PHENANTHRENE 0.056 0.193

Source: MP&M pollutant loadings.
12-37

12.0 - Pollutant Loading and Reduction Estimates

Table 12-20

Top Pollutants Removed by Option 10 for Shipbuilding

Dry Dock Indirect Dischargers

Pollutant Name

Toxic Pound Equivalents Removed

(lb-eq/yr) Pounds Removed (lb/yr)

BORON 26.1 145

MOLYBDENUM 0.062 0.309

MANGANESE 0.030 0.426

Source: MP&M pollutant loadings.
13.0 Non-Water Quality Impacts

13-1

13.0 NON-WATER QUALITY IMPACTS

Sections 304(b) and 306 of the Clean Water Act require EPA to consider nonwater quality environmental impacts (including energy requirements) associated with effluent

limitations guidelines and standards. To comply with these requirements, EPA considered the

potential impact of the proposed MP&M rule on energy consumption, air emissions, and solid

waste generation. A discussion of the proposed technology options is given in Section 14 of this

document.

Considering energy use and environmental impacts across all media, the Agency

has determined that the impacts identified in this section are justified by the benefits associated

with compliance with the proposed limitations and standards. 

Section 13.1 discusses the energy requirements for implementing wastewater

treatment technologies at MP&M facilities. Section 13.2 presents the impact of the proposed

technologies on air emissions, and section 13.3 discusses the impact on wastewater treatment

sludge and waste oil generation. 

13.1 Energy Requirements

EPA estimates that compliance with this rule will result in a net increase in energy

consumption at MP&M facilities. Table 13-1 presents estimates of energy usage by technology

option.

Table 13-1

Energy Usage by Option

Option

Incremental

Energy Requireda

(106 kilowatt

hrs/yr)

Basic Technology (Options 1, 5, and 9) 181

Basic Technology with Water Conservation and Pollution Prevention (Options 2, 6, and 10) 208

Advanced Technology (Options 3 and 7) 1,747

Advanced Technology with Water Conservation and Pollution Prevention (Options 4 and 8) 1,736

Selected Option for Existing Sourcesb (Options 2, 6, and 10 with flow cutoffs) 116

Source: MP&M Design and Cost Model output.

a The amount of additional energy required (from baseline) if the technology option is implemented, summed for all

regulated facilities.

b

 The Selected Option for Existing Sources regulates fewer MP&M facilities than other options shown in the table

due to flow cutoffs (see Section 14).
13.0 Non-Water Quality Impacts

13-2

For the Basic Technology option, EPA found that options with pollution

prevention and water conservation practices (Options 2, 6, 10) may use slightly more additional

energy as compared to those without pollution prevention and water conservation (Options 1, 5,

9). This may be due to the number of facilities that have the Basic Technology option treatment

in place prior to the regulation (leading to a smaller incremental energy requirement) compared

to the number of facilities that have pollution prevention and water conservation in place prior to

the regulation (leading to a higher incremental energy requirement). Note that the reverse is true

for the Advanced Technology option. However, the Advanced Technology option (with or

without pollution prevention) consumes much more additional energy than the basic option.

The Advanced Technology options (3/7 and 4/8) include ultrafiltration and

microfiltration technologies which require significant amounts of energy in comparison to the

oil/water separators and clarifiers required for Basic Technology options (1/5/9 and 2/6/10). The

Selected Option for Existing Sources requires the least amount of additional energy consumption

because fewer MP&M facilities will be affected than other options shown in the table due to

proposed flow cutoffs. (See Section 14 for a discussion of flow cutoffs).

Approximately 3,123 billion kilowatt hours of electric power were generated in

the United States in 1997 (1). Additional energy requirements to implement EPA’s proposed

option correspond to approximately 0.01 percent of the national requirements. The increase in

energy requirements due to the implementation of MP&M technologies will in turn cause an air

emissions impact from the electric power generation facilities providing the additional energy. 

EPA expects the increase in air emissions to be minimal as it is proportional to the increase in

energy requirements, or approximately 0.01 percent. 

13.2 Air Emissions Impacts

The Agency believes that the in-process and end-of-pipe technologies included in

the technology options for this rule do not generate significant air emissions.

EPA is developing National Emission Standards for Hazardous Air Pollutants

(NESHAPs) under Section 112 of the Clean Air Act (CAA) to address air emissions of the

hazardous air pollutants (HAPs) listed in Title III of the CAA Amendments of 1990 (CAAA).

Below is a list of current and upcoming NESHAPs that may potentially affect HAP-emitting

activities at MP&M sites: 

C Chromium Emissions from Hard and Decorative Chromium Electroplating

and Chromium Anodizing Tanks - Proposed December 16, 1993 and

promulgated on January 25, 1995;

C Halogenated Solvent Cleaning - Proposed November 29, 1993 and

promulgated on December 2, 1994; 
13.0 Non-Water Quality Impacts

13-3

C Aerospace Manufacturing - Proposed June 6, 1994 and promulgated on

July 31, 1995; 

C Shipbuilding and Ship Repair (Surface Coating);

C Large Appliances (Surface Coating);

C Metal Furniture (Surface Coating);

C Automobile and Light-Duty Truck Manufacturing (Surface Coating); and

C Miscellaneous Metal Parts and Products (Surface Coating) - scheduled for

promulgation on November 15, 2000.

These NESHAPs define the maximum achievable control technology (MACT) for

emissions of HAPS. Like effluent guidelines, MACT standards are technology-based. The

CAAA set maximum control requirements on which MACT can be based for new and existing

sources.

Halogenated HAP solvents (e.g., methylene chloride, perchloroethylene,

trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, and chloroform) used for cleaning

in the MP&M industry can be a source of hazardous air emissions. EPA believes the proposed

MP&M rule will not affect the use of solvents containing halogenated hazardous air pollutants in

the MP&M industry. This rule neither requires nor discourages the use of aqueous cleaners in

lieu of halogenated hazardous air pollutant solvents. 

13.3 Solid Waste Generation

Solid waste generated at MP&M sites includes hazardous and nonhazardous

wastewater treatment sludge as well as waste oil removed in wastewater treatment. EPA

estimates that compliance with this proposed rule will result in a decrease in wastewater

treatment sludge and an increase in waste oil generated at MP&M facilities. Sections 13.3.1 and

13.3.2 discuss the impacts of the proposed rule on the generation of wastewater treatment sludge

and waste oil, respectively.

13.3.1 Wastewater Treatment Sludge

Based on EPA’s detailed questionnaires (see Section 3.0), the Agency estimates

that MP&M facilities generated 267 million gallons of wastewater treatment sludge in 1996. 

EPA estimates that implementing the proposed wastewater treatment technology options (which

incorporate water conservation and pollution prevention practices) will reduce sludge generation. 

Table 13-2 presents the amount of wastewater treatment sludge expected to be reduced as a result

of implementing each of the technology options. 
13.0 Non-Water Quality Impacts

13-4

Table 13-2

Wastewater Treatment Sludge by Option

Option

Reduction in

Sludge

Generateda

 (million

gal/yr)

Basic Technology (Options 1, 5, and 9) 62.9

Basic Technology with Water Conservation and Pollution Prevention (Options 2, 6, and 10) 63.6

Advanced Technology (Options 3 and 7) 62.8

Advanced Technology with Water Conservation and Pollution Prevention (Options 4 and 8) 62.9

Selected Option for Existing Sourcesb (Options 2, 6, and 10 with flow cutoffs) 61.1

Source: MP&M Design and Cost Model output

aReduction in the amount of sludge generated (from baseline) if the technology option is implemented, summed for

all regulated facilities.

bThe Selected Option for Existing Sources regulates fewer MP&M facilities than other options shown in the table

due to flow cutoffs (see Section 14).

As shown in Table 13-2, wastewater treatment sludge generation decreases with

implementation of the wastewater treatment technology options. These options include sludge

dewatering, which decreases sludge generation at sites that have chemical precipitation and

settling technologies without sludge dewatering in place at baseline. EPA did not estimate

sludge reduction at sites that already practice sludge dewatering. 

The water conservation and pollution prevention technologies result in a greater

sludge reduction. EPA expects these technologies to reduce sludge generation for the following

reasons:

C Water conservation technologies reduce the amount of source water used

and thus mass of metals in the source water entering the unit processes at a

site (e.g., calcium, sodium), which reduces the amount of sludge generated

during metals removal.

C Recycling of coolants and paint curtain wastewater reduces the mass of

metal pollutants in treatment system influent streams, which reduces the

amount of sludge generated during metals removal. 

C Bath maintenance practices, including good operational practices

regarding drag-out in plating processes, reduce the mass of metal

pollutants in treatment system influent streams, which in turn reduces the

amount of sludge generated during metals removal.
13.0 Non-Water Quality Impacts

13-5

EPA classifies many sludges generated at MP&M facilities as either listed or

characteristic hazardous wastes under the Resource Conservation and Recovery Act (RCRA) as

follows:

C EPA classifies the sludge resulting from electroplating operations as EPA

hazardous waste code F006 (40 CFR 261.31). If the facility mixes the

wastewater from these electroplating operations with other

nonelectroplating wastewater for treatment, EPA still considers all of the

sludge generated from the treatment of this commingled waste stream to

be a listed hazardous waste F006; or

C If the sludge or waste oil from wastewater treatment exceeds the standards

for the Toxicity Characteristic (i.e, is hazardous), or exhibits other RCRAdefined hazardous characteristics (e.g., reactive, corrosive, or flammable),

EPA considers it a characteristic hazardous waste (40 CFR 261.24).

EPA does not include chemical conversion coating, electroless plating, and

printed circuit board manufacturing under the F006 listing (51 FR 43351, December 2, 1986). If

the facility performs certain chemical conversion coating operations on aluminum, EPA

classifies the resulting sludge as EPA hazardous waste number F019.

State and local regulations may also define MP&M sludges as hazardous wastes. 

Facilities should check with the applicable authorized authority to determine if other regulations

apply.

Based on information collected during site visits and sampling episodes, the

Agency believes that some of the solid waste generated at MP&M facilities would not be

classified as hazardous. However, for the purpose of compliance cost estimation, the Agency

assumed that all solid waste generated as a result of implementing the proposed technology

options would be hazardous.

13.3.2 Waste Oil

Based on the Agency’s detailed questionnaire, EPA estimates that MP&M

facilities generated 805 million gallons of waste oil in 1996. Table 13-3 presents the amount of

additional waste oil expected to be removed as a result of implementing each of the technology

options.
13.0 Non-Water Quality Impacts

13-6

Table 13-3

Waste Oil Removed by Option

Option

Incremental

Waste Oil

Removeda

(million gal/yr)

Basic Technology (Options 1, 5, and 9) 1,350

Basic Technology with Water Conservation and Pollution Prevention (Options 2, 6, and 10) 944

Advanced Technology (Options 3 and 7) 597

Advanced Technology with Water Conservation and Pollution Prevention (Options 4 and 8) 585

Selected Option for Existing Sourcesb (Options 2, 6, and 10 with flow cutoffs) 841

Source: MP&M Design and Cost Model output.

aThe amount of additional oil removed (from baseline) if the technology option is implemented, summed for all

regulated facilities.

bThe Selected Option for Existing Sources regulates fewer MP&M facilities than other options shown in the table

due to flow cutoffs (see Section 14).

The removal of oil from MP&M wastewater prior to discharge to POTWs or

surface waters results in an increase in waste oil generation from baseline to the proposed

options. MP&M facilities usually either recycle waste oil on or off site, or contract haul it for

disposal as either a hazardous or nonhazardous waste. The increase in waste oil generation

reflects better removal of oil from the wastewater, and does not reflect an increase in overall oil 

use at MP&M facilities. For the purpose of compliance cost estimation, EPA assumed that all

waste oil was contract hauled for disposal; however, EPA expects that some of the waste oil can

be recycled either on or off site.

The decrease in waste oil removed from Options (1/5/9) to Options (2/6/10) is due

to the 80 percent reduction of coolant discharge using the recycling technology included in the

Options (2/6/10) technology trains. This system recovers and recycles oil-bearing machining

coolants at the source, reducing the generation of spent coolant and extending the useful life of

the coolant. The decrease in waste oil removed from Options (2/6/10) to the Selected Option for

Existing Sources is due to the decrease in the number of regulated MP&M facilities as a result of

the proposed flow cutoffs. (See Section 14 for discussion of flow cutoffs).

13.4 References

1. The Energy Information Administration. Electric Power Annual 1998 Volume 1,

Table A1, 1998.
14.0 - Effluent Limitations and Standards

14-1

14.0 EFFLUENT LIMITATIONS AND STANDARDS

This section presents the proposed MP&M effluent limitations guidelines and

standards for each regulatory level of control required by the Clean Water Act (CWA) and

discusses the technology options. Section 1.0 discusses these levels of control. The proposed

limitations and standards are based on the technologies included in Options 2, 4, 6 and 10, as

discussed in Section 9.0. Except for the Steel Forming and Finishing Subcategory, the proposed

MP&M effluent limitations guidelines and standards consist of concentration-based limitations

for all new and existing direct and indirect dischargers within the scope of the proposed rule. 

The proposed MP&M effluent limitations guidelines and standards for the Steel Forming and

Finishing Subcategory consist of mass-based limitations for all new and existing direct and

indirect dischargers. In this Section, EPA provides its rationale for proposing different levels for

the low flow exclusion for indirect dischargers in various subcategories. Direct dischargers are

sites that discharge wastewater to a surface water. Indirect dischargers are sites that discharge

wastewater to a publicly owned treatment works (POTW).

Sections 14.1 through 14. 7 discuss EPA’s rationale for selecting the proposed

option and summarizes the effluent limitations and standards for each of the regulatory levels of

control for each subcategory. The Statistical Support Document for the Proposed Effluent

Limitations Guidelines and Standards for the Metal Products & Machinery Industry [EPA-821-

B-00-006] contains detailed information on those facilities EPA used in calculating the proposed

BPT limitations and establishes the statistical methodology for developing numerical discharge

limitations. Section 10.0 of this document summarizes EPA’s methodology for calculating

effluent limits, Section 9.0 discusses in detail all of the MP&M technology options, and Sections

11.0 and 12.0 discuss costs and loads, respectively.

14.1 Best Practicable Control Technology Currently Available (BPT)

EPA defines BPT effluent limits for conventional, toxic (priority), and nonconventional pollutants for direct discharging facilities. In specifying BPT, EPA looks at a

number of factors. EPA first considers the cost of achieving effluent reductions in relation to the

effluent reduction benefits. The Agency also considers the age of the equipment and facilities,

the processes employed and any required process changes, engineering aspects of the control

technologies, non-water quality environmental impacts (including energy requirements), and

such other factors as the Agency deems appropriate (CWA 304(b)(1)(B)). Traditionally, EPA

establishes BPT effluent limitations based on the average of the best performances of facilities

within the industry of various ages, sizes, processes, or other common characteristics. Where

existing performance is uniformly inadequate, EPA may require higher levels of control than are

currently in place in an industrial category if the Agency determines that the technology can be

practically applied. See “A Legislative History of the Federal Water Pollution Control Act

Amendments of 1972,” U.S. Senate Committee of Public Works, Serial No. 93-1, January 1973,

p. 1468.
14.0 - Effluent Limitations and Standards

14-2

In addition, CWA Section 304(b)(1)(B) requires a cost-reasonableness assessment

for BPT limitations. In determining the BPT limits, EPA must consider the total cost of

treatment technologies in relation to the effluent reduction benefits achieved. This inquiry does

not limit EPA's broad discretion to adopt BPT limitations that are achievable with available

technology unless the required additional reductions are “wholly out of proportion to the costs of

achieving such marginal level of reduction.” See Legislative History, op. cit. p. 170. Moreover,

the inquiry does not require the Agency to quantify benefits in monetary terms. See, for

example, American Iron and Steel Institute v. EPA, 526 F. 2d 1027 (3rd Cir., 1975). For the

BPT cost-reasonableness assessment, EPA used the total pounds of chemical oxygen demand

(COD) removed for the General Metals, Metal Finishing Job Shops, Non-Chromium Anodizing,

Steel Forming and Finishing, Oily Wastes, and Railroad Line Maintenance subcategories because

this parameter best represented the pollutant removals without counting removals of individual

pollutants more than once. EPA used oil and grease for the cost-reasonableness assessment for

the Shipbuilding Dry Dock Subcategory because it best represented the pollutant removals for

this subcategory without counting removals of individual pollutants more than once.

In balancing costs against the benefits of effluent reduction, EPA considers the

volume and nature of expected discharges after application of BPT, the general environmental

effects of pollutants, and the cost and economic impacts of the required level of pollution control. 

In past effluent limitations guidelines and standards, BPT cost-reasonableness has ranged from

$0.94/lb removed to $34.34/lb removed in 1996 dollars. In developing guidelines, the CWA

does not require or permit consideration of water quality problems attributable to particular point

sources, or water quality improvements in particular bodies of water. Therefore, EPA did not

consider these factors in developing the proposed MP&M limitations. See Weyerhaeuser

Company v. Costle, 590 F. 2d 1011 (D.C. Cir. 1978).

Table 14-1 summarizes the pounds of pollutants removed for direct dischargers,

and Table 14-2 summarizes the costs, costs per pound removed, and economic impacts for direct

dischargers associated with each of the proposed options by subcategory. (See Section 14.4 for

summary tables for indirect dischargers.)

EPA notes that the pounds removed presented in Table 14-1 may differ from the

pounds removed presented in the Economic, Environmental, and Benefits Analysis of the

Proposed Metal Products & Machinery Rule [EPA-821-B-00-0058]. This document presents the

methodology employed to assess economic and environmental impacts of the proposed rule and

the results of the analysis. The difference in pounds removed occurs because the Agency does

not include facilities (or the associated pollutant loadings and removals) that closed at the

baseline (i.e., EPA predicted that these facilities would close prior to the implementation of the

MP&M rule) when performing certain economic analyses (e.g., cost-effectiveness). Table 14-1

estimates the annual pounds removed by the selected option for all of the direct discharging

facilities in EPA’s questionnaire database that discharged wastewater at the time EPA collected

the data. 
14.0 - Effluent Limitations and Standards

14-3

Table 14-1

Pounds of Pollutants Removed by the Proposed BPT Option for Direct Dischargers by Subcategory

Subcategory a

(Number of Facilities)

Selected

Option

 Total

Suspended

Solids 

(lbs

removed/yr)

Oil and

Grease

(lbs

removed/yr)

Chemical

Oxygen

Demand

(lbs

removed/yr) 

Priority and

Nonconventional

Metals

(lbs removed/yr) 

Priority and

Nonconventional

Organics 

(lbs removed/yr) 

Cyanide

(lbs

removed/yr) 

General Metals (3,794) Option 2 10.1 million 7.8 million 181 million 4 million 5 million 184,000

Metal Finishing Job Shops (15)b Option 2 13,000 14,400 232,000 34,000 4,600 5,700

Printed Wiring Boards (11)b Option 2 51,000 238,000 1.3 million 172,000 22,000 1,400

Steel Forming and Finishing (43) Option 2 884,000 101,000 4.5 million 387,000 76,000 1,100

Oily Wastes (911) Option 6 349,000 885,000 5.1 million 81,000 127,000 10

Railroad Line Maintenance (34) Option

10

9,000 47,400 59,000 1,000 78 0

Shipbuilding Dry Dock (6) Option

10

650 8.5 million 0 1,400 700 0

a

 EPA did not identify any direct discharging facilities in the Non-Chromium Anodizing Subcategory; therefore, there are no estimated removals. See Section

14.1.3.

bAlthough EPA is not revising limits for TSS and O&G for these two subcategories, removals are reported based on incidental removals for the proposed

MP&M Option 2 technology for BPT control of toxic and nonconventional pollutants.
14.0 - Effluent Limitations and Standards

14-4

Table 14-2

Annualized Costs and Economic Impacts of the Proposed BPT Option for 

Direct Dischargers by Subcategory

Subcategory a

(Number of

Facilities)

Selected

Option

Annualized Compliance

Costs for Selected Option

($1996) 

Economic Impacts

(Facility Closures) of

Selected Option

(Percentage of

Regulated

Subcategory)

BPT Cost per

Pound Removed b

(1996 $/pound

removed)

General Metals

(3,794)

Option 2 230 million 20 (<1%) 1.22

Metal Finishing

Job Shops (15)

Option 2 1.3 million 0 5.60

Printed Wiring

Boards (11)

Option 2 2.5 million 0 1.92

Steel Forming

and Finishing

(43)

Option 2 29.3 million 0 6.51

Oily Wastes

(911)

Option 6 11.2 million 0 2.18

Railroad Line

Maintenance

(34)

Option

10

1.18 million 0 20.00

Shipbuilding 

Dry Dock (6) 

Option 

10 

2.15 million 0 0.25

a

 EPA did not identify any direct discharging facilities in the Non-Chromium Anodizing Subcategory; therefore,

there are no estimated costs. See Section 14.1.3 for estimates based on a model facility.

b

 EPA based the pounds used in calculating the BPT cost reasonableness on the COD removals only (shown in

Table 14-1) for each subcategory, except for the use of oil and grease removals only (shown in Table 14-1) for the

Shipbuilding Dry Dock Subcategory. 
14.0 - Effluent Limitations and Standards

14-5

14.1.1 BPT Technology Selection for General Metals Subcategory

Section 6.2.1 describes the General Metals Subcategory. The Agency estimates

that there are approximately 3,800 direct discharging facilities in the General Metals

Subcategory. EPA estimates that the direct discharging facilities in the General Metals

Subcategory currently discharge substantial quantities of pollutants into the surface waters of the

United States, including 8.2 million pounds per year of oil and grease, 10.9 million pounds per

year of total suspended solids (TSS), 187 million pounds of COD, 5.2 million pounds per year of

priority and nonconventional metal pollutants, 5.2 million pounds of priority and

nonconventional organic pollutants, and 187,000 pounds per year of cyanide. As a result of the

quantity of pollutants currently discharged directly to the nation’s waters by General Metals

facilities, EPA determined that there was a need for BPT regulation for this subcategory.

Facilities in the General Metals Subcategory generally perform unit operations

such as cleaning, etching, electroplating, electroless plating, and conversion coating that produce

metal-bearing wastewater. In addition, some of these facilities also perform machining and

grinding, impact deformation, and surface preparation operations that generate oily wastewater. 

Therefore, EPA considered technology options 1 through 4 for this subcategory because

technologies included in these options treat both oily wastewater and metal-bearing wastewater. 

As explained above, EPA only discusses options 2 and 4 in detail in this section since these

options costed less and removed more pollutants than options 1 and 3, respectively. See Section

9.0 for a discussion of technology options. 

The Agency selected Option 2 as the basis for BPT regulation for the General

Metals Subcategory. EPA's decision to base BPT limitations on Option 2 treatment reflects

primarily two factors: (1) the degree of effluent reductions attainable, and (2) the total cost of the

proposed treatment technologies in relation to the effluent reductions achieved. EPA found no

basis for identifying different BPT limitations based on age, size, process, or other engineering

factors. Neither the age nor the size of a facility in the General Metals Subcategory will directly

affect the treatability of MP&M process wastewater. For facilities in this subcategory, the most

pertinent factors for establishing the limitations are costs of treatment and the level of effluent

reductions obtainable.

Tables 14-1 and 14-2 present the annual pollutant removals for direct dischargers

for Option 2 and the cost per pound removed using only the pounds of COD removed,

respectively. EPA estimates that implementation of Option 2 will cost $1.22 per pound of COD

removed (1996 dollars). The Agency has concluded that the costs of BPT Option 2 are

achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 2 represents the average of the best

performing facilities due to the prevalence of chemical precipitation followed by sedimentation

in this subcategory. Approximately 22 percent of the direct discharging facilities in the General

Metals Subcategory employ chemical precipitation followed by a clarifier (Option 2), while less

than 1 percent employ microfiltration after chemical precipitation (Option 4). 
14.0 - Effluent Limitations and Standards

14-6

Based on the available database, Option 4 only removes, on an annual basis, an

additional 66,000 pounds of TSS, 12,300 pounds of oil and grease, 15,000 pounds of priority

metals, and 880,000 pounds of nonconventional metals, while removing 324,000 pounds less

COD and 31,000 pounds less priority and nonconventional organic pollutants than Option 2. 

Although there is a large amount of additional removals of TSS and nonconventional metals for

Option 4 when considered across the entire population (3,800 facilities), the Agency determined

that these additional removals were not significant when considered on a per-facility basis. In

addition, Option 4's annualized cost is $52 million more than Option 2. EPA concluded that the

lack of significant additional pollutant removals per facility achieved by Option 4 (and the fact

that it removes less COD and organic pollutants) support the selection of Option 2 as the BPT

technology basis. Table 14-3 lists the proposed BPT limitations for existing point sources in the

General Metal Subcategory. EPA’s data editing procedures and statistical methodology for

calculating BPT limitations are explained in Section 10.0. 

Existing direct discharging facilities in the General Metals Subcategory must

achieve the following effluent limitations representing the application of BPT. Discharges must

remain within the pH range 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-7

Table 14-3

BPT/BAT Effluent Limitations for the General Metals Subcategory

Regulated Parameter

Maximum

Daily (mg/L (ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 34 18

2. Oil and Grease (as HEM) 15 12

3. Total Organic Carbon (TOC) (as indicator) 87 50

4. Total Organics Parameter (TOP) 9.0 4.3

5. Cadmium 0.14 0.09

6. Chromium 0.25 0.14

7. Copper 0.55 0.28

8. Total Cyanide 0.21 0.13

9. Amenable Cyanide 0.14 0.07

10. Lead 0.04 0.03

11. Manganese 0.13 0.09

12. Molybdenum 0.79 0.49

13. Nickel 0.50 0.31

14. Silver 0.22 0.09

15. Sulfide, Total 31 13

16. Tin 1.4 0.67

17. Zinc 0.38 0.22

As explained in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. 

14.1.2 BPT Technology Selection for Metal Finishing Job Shops Subcategory

Section 6.2.2 describes the Metal Finishing Job Shops Subcategory. The Agency

estimates that there are approximately 15 direct discharging facilities in the Metal Finishing Job

Shops Subcategory. EPA previously promulgated BPT and best available technology

economically achievable (BAT) limitations for all of the facilities in this subcategory at 40 CFR

Part 413 (Electroplating Pretreatment Standards) and at 40 CFR Part 433 (Metal Finishing

Effluent Limitations Guidelines and Pretreatment Standards). However, EPA developed the

existing regulations applicable to the facilities in the Metal Finishing Job Shops Subcategory

approximately 20 years ago, and since that time, advances in electroplating and metal finishing
14.0 - Effluent Limitations and Standards

14-8

processes, water conservation, pollution prevention, and wastewater treatment have occurred. 

EPA is proposing new BPT effluent limitations guidelines for this subcategory. 

EPA estimates that direct discharging facilities in the Metal Finishing Job Shops

Subcategory currently discharge substantial quantities of pollutants to the surface waters of the

United States, including 17,900 pounds per year of oil and grease, 20,500 pounds per year of

TSS, 287,400 pounds per year of COD, 44,000 pounds per year of priority and nonconventional

metal pollutants, 6,000 pounds per year of priority and nonconventional organic pollutants, and

6,000 pounds per year of cyanide. As a result of the quantity of pollutants currently discharged

directly to the nation’s waters by metal finishing job shop facilities, EPA determined that there is

a need for BPT regulation for this subcategory. 

Facilities in the Metal Finishing Job Shops Subcategory generally perform unit

operations such as cleaning, etching, electroplating, electroless plating, passivating, and

conversion coating that produce metal-bearing wastewater. In addition, some of these facilities

also perform machining and grinding, impact deformation, and surface preparation operations

that generate oily wastewater. Therefore, EPA considered technology options 1 through 4 for

this subcategory because technologies included in these options treat both oily wastewater as well

as metal-bearing wastewater. As explained above, EPA only discusses Options 2 and 4 in detail

in this section since these options costed less and removed more pollutants than Options 1 and 3,

respectively. 

The Agency selected Option 2 as the basis for BPT regulation for the Metal

Finishing Job Shops Subcategory. The new BPT limitations incorporate more stringent effluent

requirements for priority metals, nonconventional pollutants, cyanide, and organic pollutants (by

way of an indicator parameter) as compared to the limitations contained in 40 CFR 433.13. EPA

has included the conventional pollutants, TSS and oil and grease, in the new BPT regulation for

this subcategory at the same level as 40 CFR 433.13. EPA's decision to base BPT limitations on

Option 2 treatment reflects primarily two factors: (1) the degree of effluent reductions attainable

and (2) the total cost of the proposed treatment technologies in relation to the effluent reductions

achieved. No basis could be found for identifying different BPT limitations based on age, size,

process, or other engineering factors. Neither the age nor the size of a facility in the Metal

Finishing Job Shops Subcategory will directly affect the treatability of MP&M process

wastewater. For facilities in this subcategory, the most pertinent factors for establishing the

limitations are costs of treatment and the level of effluent reductions obtainable. EPA based its

decision not to revise the conventional pollutant limitations on the use of the alternate organics

control parameters (i.e., TOC or TOP) and the small additional removals of TSS obtainable after

the incidental removal due to control of the metals.

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 2; Table 14-2 presents the cost per pound removed using only the pounds of COD

removed. EPA estimates that implementation of Option 2 will cost $5.60 per pound of COD

removed (1996 dollars). The Agency has concluded that the costs of BPT Option 2 are

achievable and are reasonable as compared to the removals achieved by this option.
14.0 - Effluent Limitations and Standards

14-9

The technology proposed in Option 2 represents the average of the best

performing facilities due to the prevalence of chemical precipitation followed by sedimentation

in the subcategory. The Agency estimates that 100 percent of the direct discharging facilities in

the Metal Finishing Job Shops Subcategory employ chemical precipitation followed by a clarifier

(Option 2) while no facilities employ microfiltration after chemical precipitation (Option 4). 

Because no facilities in this subcategory employ microfiltration after chemical precipitation for

solids separation, the Agency concluded that Option 4 does not represent the average of the best

treatment. 

Based on the available data base, Option 4 only removes, on an annual basis, an

additional 6,900 pounds of priority and nonconventional metals, while removing 1,500 pounds

less COD, and 600 pounds less priority and nonconventional organic pollutants than Option 2. 

EPA concluded that the lack of significant overall additional pollutant removals achieved by

Option 4 (and the fact that it removes less COD and organic pollutants) support the selection of

Option 2 as the BPT technology basis. Table 14-4 lists the proposed BPT limitations for the

Metal Finishing Job Shops Subcategory.

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. In general, EPA calculated the new BPT limitations for

this subcategory using data from facilities in the Metal Finishing Job Shops Subcategory

employing Option 2 technology. As discussed above, EPA did not calculate new limitations for

TSS or oil and grease for this subcategory. Instead, EPA set them at the same level as in the

Metal Finishing effluent guidelines (40 CFR 433.13). For cyanide limitations, EPA used data

from all subcategories where cyanide destruction systems were sampled. If data was not

sufficient for developing BPT limitations for an individual pollutant in this subcategory, the

Agency transferred data from another subcategory. 

Existing direct discharging facilities in the Metal Finishing Job Shops

Subcategory must achieve the following effluent limitations representing the application of BPT. 

Discharges must remain within the pH range 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-10

Table 14-4

BPT/BAT Effluent Limitations for the

Metal Finishing Job Shops Subcategory

Regulated Parameter

Maximum

Daily (mg/L (ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 60 31

2. Oil and Grease (as HEM) 52 26

3. Total Organic Carbon (TOC) (as indicator) 78 59

4. Total Organics Parameter (TOP) 9.0 4.3

5. Cadmium 0.21 0.09

6. Chromium 1.3 0.55

7. Copper 1.3 0.57

8. Total Cyanide 0.21 0.13

9. Amenable Cyanide 0.14 0.07

10. Lead 0.12 0.09

11. Manganese 0.25 0.10

12. Molybdenum 0.79 0.49

13. Nickel 1.5 0.64

14. Silver 0.15 0.06

15. Sulfide, Total 31 13

16. Tin 1.8 1.4

17. Zinc 0.35 0.17

As explained in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. 

14.1.3 BPT Technology Selection for Non-Chromium Anodizing Subcategory

Section 6.2.3 describes the Non-Chromium Anodizing Subcategory. EPA’s

survey of the MP&M industry did not identify any non-chromium anodizing facilities

discharging directly to surface waters. All of the non-chromium anodizing facilities in EPA’s

data base are either indirect or zero dischargers. EPA consequently could not evaluate any

treatment systems in place at direct discharging non-chromium anodizing facilities for

establishing BPT limitations. Therefore, EPA relied on technology transfer based on information
14.0 - Effluent Limitations and Standards

14-11

and data from indirect discharging facilities in the Non-Chromium Anodizing Subcategory. The

Agency concluded that the technology in place at some indirect discharging non-chromium

anodizing facilities is appropriate to use as the basis for regulation of direct dischargers because

the pollutant profile of the wastewater generated at those facilities discharging directly would be

similar in character to that from indirect discharging non-chromium anodizing facilities and the

model technologies in place at indirect dischargers are effective in treating the conventional

pollutants that are generally not regulated in pretreatment standards. 

EPA previously promulgated BPT and BAT limitations for all of the facilities in

this subcategory at 40 CFR Part 433 (Metal Finishing Effluent Limitations Guidelines and

Pretreatment Standards). However, EPA developed the regulations applicable to this

subcategory approximately 20 years ago, and since that time, advances in anodizing processes,

water conservation, pollution prevention, and wastewater treatment have occurred. EPA is

proposing to set new BPT effluent limitations guidelines for this subcategory for metals, but is

not revising the limitations for conventional pollutants (TSS and oil and grease). EPA based its

decision not to revise the limitations for conventional pollutants on the small additional removals

attainable after the incidental removal due to control of the metals.

In addition, the current regulations in 40 CFR Part 433 require non-chromium

anodizing facilities to meet effluent limitations for seven metal pollutants. EPA’s data show that

these seven metals are present only in very small quantities in the current discharges at nonchromium anodizing facilities. Under the Metal Finishing effluent guidelines, EPA did not

establish a BPT limit for aluminum, the metal found in the largest quantity in non-chromium

anodizing facilities wastewater. The Agency has determined that direct discharging facilities in

the Non-Chromium Anodizing Subcategory should have a limit for aluminum and thus is

proposing to replace BPT in 40 CFR Part 433 with new MP&M effluent limitations that more

appropriately reflect the pollutants found in non-chromium anodizing wastewater. EPA notes

that the Agency expects a reduction in monitoring burden associated with this revision for direct

discharge non-chromium anodizing facilities. 

Facilities in the Non-Chromium Anodizing Subcategory generally perform unit

operations such as cleaning, etching, and anodizing of aluminum that produce metal-bearing

wastewater. The majority of the metal found in anodizing wastewater is aluminum. In addition,

some of these facilities also perform machining and grinding, impact deformation, and surface

preparation operations that generate oily wastewater. Therefore, EPA considered technology

options 1 through 4 for this subcategory because technologies included in these options treat both

oily wastewater as well as metal-bearing wastewater. As explained above, EPA only discusses

Options 2 and 4 in detail in this section since these options costed less and removed more

pollutants than Options 1 and 3, respectively.

The Agency selected Option 2 as the basis for BPT regulation for the NonChromium Anodizing Subcategory. Although EPA did not identify any existing non-chromium

anodizing facilities from the detailed survey, EPA estimated the cost of treatment and pollutant

removal for a median-sized direct discharging facility with a wastewater flow of 6.25 million
14.0 - Effluent Limitations and Standards

14-12

gallons per year, based on the characteristics of a similarly sized indirect discharging nonchromium anodizing facility. Because direct dischargers are more likely to have treatment in

place, EPA provided the model facility with treatment in place equivalent to Option 1. 

Therefore, at the model direct discharging non-chromium anodizing facility, EPA estimates that

implementation of Option 2 will cost $0.83 per pound of COD removed (1996 dollars), and has

found that cost to be reasonable. EPA estimates that Option 2 would remove 25,700 pounds of

pollutants per median-sized facility per year (including 9,200 pounds of TSS and 1,240 pounds

of aluminum as incidental removals based on the control of metals).

Additionally, because solids separation by microfiltration is not used by any nonchromium anodizing facilities, the Agency concluded that Option 4 does not represent BPT for

this subcategory. Table 14-5 lists the proposed BPT limitations for the Non-Chromium

Anodizing Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. Because EPA’s survey did not identify any direct

dischargers in the Non-Chromium Anodizing Subcategory, EPA used data from indirect

discharging facilities to develop the BPT limitations. The Agency identified two indirect

discharging facilities in this subcategory that achieved very good pollutant reductions (including,

on average, 96 percent reduction of aluminum and incidental removals of 95 percent for TSS). 

Therefore, EPA determined that the data from these facilities were appropriate for the

development of BPT limitations. If data was not sufficient for developing BPT limitations for an

individual pollutant in this subcategory, the Agency transferred data from another subcategory. 

In the case of TSS and oil and grease, EPA used the limitations in 40 CFR 433.13. The

Statistical Development Document contains detailed information on which facilities EPA used in

calculating the proposed BPT limitations.

Existing direct discharging facilities in the Non-Chromium Anodizing

Subcategory must achieve the following effluent limitations representing the application of BPT. 

Discharges must remain within the pH range 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-13

Table 14-5

BPT/BAT Effluent Limitations for the

Non-Chromium Anodizing Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 60 31

2. Oil and Grease (as HEM) 52 26

3. Aluminum 8.2 4.0

4. Manganese 0.13 0.09

5. Nickel 0.50 0.31

6. Zinc 0.38 0.22

14.1.4 BPT Technology Selection for Printed Wiring Board Subcategory

Section 6.2.4 describes the Printed Wiring Board Subcategory. The Agency

estimates there are approximately 11 direct discharging facilities in this subcategory. EPA has

previously promulgated BPT and BAT limitations for all of the facilities in this subcategory at 40

CFR Part 433 (Metal Finishing). However, EPA developed the regulations applicable to this

subcategory approximately 20 years ago, and since that time, advances in printed wiring board

manufacturing processes, water conservation practices, pollution prevention techniques, and

wastewater treatment have occurred. EPA is proposing to set new BPT effluent limitations

guidelines for this subcategory. 

EPA estimates that direct discharging facilities in the Printed Wiring Board

Subcategory currently discharge substantial quantities of pollutants to the surface waters of the

United States, including 262,000 pounds per year of oil and grease, 100,000 pounds per year of

TSS, 1.7 million pounds per year of COD, 242,000 pounds per year of priority and

nonconventional metal pollutants, 35,000 pounds per year of priority and nonconventional

organic pollutants, and 1,600 pounds per year of cyanide. As a result of the quantity of pollutant

currently discharged directly to the nation’s waters by printed wiring board facilities, EPA

determined that there is a need for BPT regulation for this subcategory. 

Facilities in the Printed Wiring Board Subcategory generally perform unit

operations such as cleaning, etching, masking, electroplating, electroless plating, applying,

developing and stripping of photoresist, and tin/lead soldering that produce metal-bearing and

organic-bearing wastewater. Therefore, EPA considered technology Options 1 through 4 for this

subcategory. As explained above, EPA only discusses Options 2 and 4 in detail in this document

since these options costed less and removed more pollutants than Options 1 and 3, respectively. 

Section 9.0 describes the technology options.
14.0 - Effluent Limitations and Standards

14-14

The Agency selected Option 2 as the basis for BPT regulation for the Printed

Wiring Board Subcategory. The new BPT limitations incorporate more stringent effluent

requirements for priority metals, nonconventional pollutants, cyanide, and organic pollutants (by

way of an indicator parameter) as compared to the limitations contained in 40 CFR 433.13. EPA

has included the conventional pollutants, TSS and oil and grease, in the new BPT regulation for

this subcategory at the same level as 40 CFR 433.13. Removals for these pollutants are

incidental removals based on the increased control of metals and organic pollutants (by way of an

indicator parameter) by the proposed BPT technology options. EPA's decision to base BPT

limitations on Option 2 treatment for priority metals, non conventional pollutants, cyanide and

organic pollutants reflects primarily two factors: (1) the degree of effluent reductions attainable

and (2) the total cost of the proposed treatment technologies in relation to the effluent reductions

achieved. No basis could be found for identifying different BPT limitations based on age, size,

process, or other engineering factors. Neither the age nor the size of a facility in the Printed

Wiring Board Subcategory will directly affect the treatability of MP&M process wastewater. For

facilities in this subcategory, the most pertinent factors for establishing the limitations are costs

of treatment and the level of effluent reductions obtainable.

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 2; Table 14-2 presents the cost per pound removed using only the pounds of COD

removed. EPA estimates that implementation of Option 2 will cost $1.92 per pound of COD

removed (1996 dollars). The Agency has concluded that the costs of BPT Option 2 are

achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 2 represents the average of the best

performing facilities due to the prevalence of chemical precipitation followed by sedimentation

in this subcategory. The Agency estimates that 100 percent of the direct discharging facilities in

the Printed Wiring Board Subcategory employ chemical precipitation and sedimentation

treatment (Option 2); however, the Agency did identify indirect dischargers in this subcategory

with Option 4 technology in place. In fact, EPA collected wastewater treatment samples at one

indirect discharging printed wiring board manufacturing facility that used Option 4 technology. 

Based on the available database, Option 4 only removes, on an annual basis, an

additional 48,000 pounds of priority and nonconventional metals, while removing 9,000 less

pounds of COD, and 250 less pounds of priority and nonconventional organic pollutants than

Option 2. In addition, Option 4's annualized cost is $2 million more than Option 2. EPA

concluded that the lack of significant overall additional pollutant removals achieved by Option 4

(and the fact that it removes less COD and organic pollutants) support the selection of Option 2

as the BPT technology basis. Table 14-6 lists the proposed BPT effluent limitations for the

Printed Wiring Board Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. In general, EPA calculated the new BPT limitations for

this subcategory using data from facilities in the Printed Wiring Board Subcategory employing

Option 2 technology. As discussed above, EPA did not calculate new limitations for TSS or oil
14.0 - Effluent Limitations and Standards

14-15

and grease for this subcategory. Instead, EPA set them at the same level as in the Metal

Finishing effluent guidelines (40 CFR 433.13). For cyanide limitations, EPA used data from all

subcategories where cyanide destruction systems were sampled. If data was not sufficient for

developing BPT limitations for an individual pollutant in this subcategory, the Agency

transferred data from another subcategory. 

Existing direct discharging facilities in the Printed Wiring Board Subcategory 

must achieve the following effluent limitations representing the application of BPT. Discharges

must remain within the pH range 6 to 9 and must not exceed the following.

Table 14-6

BPT/BAT Effluent Limitations for the Printed Wiring Board Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 60 31

2. Oil and Grease (as HEM) 52 26

3. Total Organic Carbon (TOC) (as indicator) 101 67

4. Total Organics Parameter (TOP) 9.0 4.3

Chromium 0.25 0.14

6. Copper 0.55 0.28

7. Total Cyanide 0.21 0.13

8. Amenable Cyanide 0.14 0.07

9. Lead 0.04 0.03

10. Manganese 1.3 0.64

11. Nickel 0.30 0.14

12. Sulfide, Total 31 13

13. Tin 0.31 0.14

14. Zinc 0.38 0.22

As explained in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either amenable

or total cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. 
14.0 - Effluent Limitations and Standards

14-16

14.1.5 BPT Technology Selection for Steel Forming and Finishing Subcategory

Section 6.2.5 describes the Steel Forming and Finishing Subcategory. The

Agency estimates there are approximately 43 direct discharging facilities in this subcategory. 

EPA previously promulgated BPT and BAT limitations for all of the facilities in this subcategory

at 40 CFR Part 420 (Iron and Steel Manufacturing Effluent Limitations Guidelines and

Pretreatment Standards). However, EPA developed the regulations applicable to this

subcategory approximately 20 years ago, and since that time, changes in the industry, particularly

in growth of the number of facilities conducting steel forming and finishing operations without

the presence of the typical steel manufacturing processes, and changes in water conservation

practices, pollution prevention techniques, and wastewater treatment have occurred. In addition,

the operations covered by the proposed rule are segments of the forming and finishing

subcategories in 40 CFR 420. The proposed MP&M subcategory is comprised of limitations

and standards based on specific forming and finishing operations only. In a separate notice, EPA

is proposing to revise other subcategories covered by the Iron and Steel Manufacturing effluent

guidelines.

EPA estimates that direct discharging facilities in the new Steel Forming and

Finishing Subcategory currently discharge substantial quantities of pollutants to the surface

waters of the United States, including 195,000 pounds per year of oil and grease, 1.08 million

pounds per year of TSS, 6 million pounds per year of COD, 771,000 pounds per year of priority

and nonconventional metal pollutants, 168,000 pounds per year of priority and nonconventional

organic pollutants, and 2,300 pounds per year of cyanide. As a result of the quantity of pollutant

currently discharged directly to the nation’s waters by steel forming and finishing facilities, EPA

determined that there is a need for BPT regulation for this subcategory. 

Facilities in the proposed MP&M Steel Forming and Finishing Subcategory

generally perform unit operations such as acid pickling, annealing, conversion coating (e.g., zinc

phosphate, copper sulfate), hot dip coating, electroplating, heat treatment, welding, and drawing

of steel bar, rod, and wire that produce metal-bearing and oil-bearing wastewater. Therefore,

EPA considered technology Options 1 through 4 for this subcategory. As explained above, EPA

only discusses Options 2 and 4 in detail in this section since these options costed less and

removed more pollutants than Options 1 and 3, respectively. 

The Agency is proposing Option 2 as the basis for the new BPT regulation for the

Steel Forming and Finishing Subcategory. EPA's decision to propose BPT limitations based on

Option 2 treatment reflects primarily two factors: (1) the degree of effluent reductions attainable

and (2) the total cost of the proposed treatment technologies in relation to the effluent reductions

achieved. No basis could be found for identifying different BPT limitations based on age, size,

process, or other engineering factors. Neither the age nor the size of a facility in the Steel

Forming and Finishing Subcategory will directly affect the treatability of MP&M process

wastewater. For facilities in this subcategory, the most pertinent factors for establishing the

limitations are costs of treatment and the level of effluent reductions obtainable.
14.0 - Effluent Limitations and Standards

14-17

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 2; Table 14-2 presents the cost per pound removed using only the pounds of COD

removed. EPA estimates that implementation of Option 2 will cost $6.51 per pound of COD

removed (1996 dollars). The Agency has concluded that the costs of BPT Option 2 are

achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 2 represents the average of the best

performing facilities due to the prevalence of chemical precipitation followed by sedimentation

in this subcategory. The Agency estimates that 64 percent of the direct discharging facilities in

this subcategory employ chemical precipitation followed by sedimentation (Option 2). Because

no facilities in this subcategory employ microfiltration after chemical precipitation for solids

separation, the Agency concluded that Option 4 does not represent BPT. Table 14-8 lists the

proposed BPT effluent limitations for the Steel Forming and Finishing Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. In general, EPA calculated BPT limitations for the

Steel Forming and Finishing Subcategory using data transferred from facilities employing Option

2 technology in the General Metals subcategory. However, EPA determined that mass-based

limitations (rather than concentration-based limitations developed for the General Metals

subcategory) are more appropriate for this subcategory. Facilities in this subcategory keep close

track of their production on a mass basis primarily because of their prior regulation under the

mass-based Iron and Steel Manufacturing effluent guidelines. Furthermore, EPA determined that

mass-based limitations are appropriate for this subcategory due to the uniform nature of the

products produced (wire, rod, bar, pipe, and tube). The uniform nature of the products produced

by this industry makes for an easier conversion from concentration-based to mass-based

limitations. One of the primary reasons that EPA is not requiring mass-based limitations for

other subcategories is the fact that most MP&M facilities do not collect production information

on a wastestream-by-wastestream basis, and therefore development of mass-based limitations

could create a significant burden for both the POTW and the MP&M facility. In the case of the

Steel Forming and Finishing subcategory, EPA is able to use the industry’s production

information to propose production-based limitations for the Steel Forming and Finishing

Subcategory.

In the proposal, EPA solicits paired treatment system influent and effluent data

from Steel Forming and Finishing facilities, so that limits may better reflect treatment at Steel

Forming and Finishing facilities. EPA also solicits comment on whether to allow concentrationbased limits for this subcategory and any rationale for doing so. For cyanide limitations, EPA

used data from all subcategories where cyanide destruction systems were sampled. The

Statistical Development Document contains detailed information on which facilities EPA used in

calculating the proposed BPT limitations.

EPA expresses the proposed effluent limitations guidelines and standards for

BPT, BAT, NSPS, PSES, and PSNS for the Steel Forming and Finishing Subcategory as mass

limitations in pounds/1,000 pounds of product. The Agency derived the mass limitations by
14.0 - Effluent Limitations and Standards

14-18

multiplying an effluent concentration (determined from the analysis of treatment system

performance) by an appropriate wastewater volume (“production-normalized flow”) determined

for each forming or finishing operation expressed in gallons/ton of product. EPA developed the

production normalized flows used to develop the limits in the proposed rule from survey

questionnaire responses from Steel Forming and Finishing facilities. The production-normalized

flows are listed in Table 14-7. 

Table 14-7

Production Normalized Flows (PNF) for Steel

Forming and Finishing

Unit Operation PNF (gallons/ton)

Acid Pickling 500

Alkaline Cleaning 500

Cold Forming 0

Continuous Annealing 25

Electroplating 1000

Hot Dip Coating 145

 Lubrication 12

Mechanical Descaling 2

Painting 65

Pressure Deformation 25

EPA defines the unit operations listed in Table 14-7 as follows.

(a) Acid pickling means the removal of scale and/or oxide from steel surfaces

using acid solutions. The mass-based limitations for acid pickling operations include wastewater

flow volumes from acid treatment with and without chromium, acid pickling neutralization,

annealing, alkaline cleaning, electrolytic sodium sulfate descaling, and salt bath descaling.

(b) Alkaline cleaning means the application of solutions containing caustic soda,

soda ash, alkaline silicates, or alkaline phosphates to a metal surface primarily for removing

mineral deposits, animal fats, and oils. The mass-based limitations for alkaline cleaning

operations include wastewater flow volumes from alkaline cleaning for oil removal, alkaline

treatment without cyanide, aqueous degreasing, and electrolytic cleaning operations. 

(c) Cold forming means operations conducted on unheated steel for purposes of

imparting desired mechanical properties and surface qualities (density, smoothness) to the steel. 

The mass-based limitations for cold forming operations are based on zero wastewater discharge. 

(d) Continuous Annealing means a heat treatment process in which steel is

exposed to an elevated temperature in a controlled atmosphere for an extended period of time
14.0 - Effluent Limitations and Standards

14-19

and then cooled. The mass-based limitations for continuous annealing operations include

wastewater flow volumes from heat treating operations.

(e) Electroplating means the application of metal coatings including, but not

limited to, chromium, copper, nickel, tin, zinc, and combinations thereof, on steel products using

an electro-chemical process. The mass-based limitations for electroplating operations includes

wastewater flow volumes from acid pickling, annealing, alkaline cleaning, electroplating without

chromium or cyanide, and electroless plating operations.

(f) Hot Dip Coating means the coating of pre-cleaned steel parts by immersion in

a molten metal bath. The mass-based limitations for hot dip coating operations includes

wastewater flow volumes from acid pickling, annealing, alkaline cleaning, chemical conversion

coating without chromium, chromate conversion coating, galvanizing, and hot dip coating

operations.

(g) Lubrication means the process of applying a substance to the surface of the

steel in order to reduce friction or corrosion. The mass-based limitations for lubrication

operations includes wastewater flow volumes from corrosion preventive coating operations as

defined in 438.61(b). 

(h) Mechanical Descaling means the process of removing scale by mechanical or

physical means from the surface of steel. The mass-based limitations for mechanical descaling

operations includes wastewater flow volumes from abrasive blasting, burnishing, grinding,

impact deformation, machining, and testing operations. 

(i) Painting means applying an organic coating to a steel bar, rod, wire, pipe, or

tube. The mass-based limitations for painting operations includes wastewater flow volumes from

spray or brush painting and immersion painting.

(j) Pressure Deformation means applying force (other than impact force) to

permanently deform or shape a steel bar, rod, wire, pipe, or tube. The mass-based limitations for

pressure deformation operations includes wastewater flow volumes from forging operations and

extrusion operations. 

EPA transferred the effluent concentrations used to develop the proposed Steel

Forming and Finishing Subcategory limitations and standards from those used for the General

Metals Subcategory because it did not collect analytical wastewater data from Steel Forming and

Finishing facilities that used the Option 2 treatment technology. EPA believes that the

wastewater characteristics of the General Metals Subcategory closely resemble those of the Steel

Forming and Finishing subcategory. EPA will conduct analytical wastewater sampling of welloperated chemical precipitation and clarification systems at Steel Forming and Finishing

facilities post-proposal. EPA intends on developing limitations and standards for this

subcategory for the final rule that would be based on the Steel Forming and Finishing facilities in

this subcategory. 

Permit writers and control authorities shall compute mass effluent limitations and

pretreatment requirements for each forming/finishing operation by multiplying the average daily

production rate (or other reasonable measure of production) by the respective effluent limitations

guidelines or standards listed in Table 14-8. In determining the production rate for the Steel
14.0 - Effluent Limitations and Standards

14-20

Forming and Finishing Subcategory, EPA is proposing to require permit writers and control

authorities to use the following protocols: 

(1) For similar, multiple production lines with process waters treated in the

same wastewater treatment system, the reasonable measure of production

shall be determined from the combined production of the similar

production lines during the same time period.

(2) For process wastewater treatment systems where wastewater from two or

more different production lines are commingled in the same wastewater

treatment system, the reasonable measure of production shall be

determined separately for each production line (or combination of similar

production lines) during the same time period.

Permit writers and control authorities shall not include production from unit

operations that do not generate or discharge process wastewater in the calculation of the

operating rate.

The mass effluent limitations or pretreatment requirements applicable at a given

NPDES or pretreatment compliance monitoring point shall be the sum of the mass effluent

limitations or pretreatment requirements for each regulated pollutant parameter within each

applicable forming/finishing operation with process wastewater discharging to that compliance

monitoring point.

Existing direct discharging facilities in the Steel Forming and Finishing

Subcategory must achieve the following effluent limitations representing the application of BPT. 

Discharges must remain within the pH range 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-21

Table 14-8

BPT/BAT Effluent Limitations for the Steel Forming

and Finishing Subcategory

Pollutant TSS O&G (as HEM)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0709 0.0369 0.0312 0.0239

(b) Alkaline Cleaning 0.0709 0.0369 0.0312 0.0239

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00355 0.00184 0.00156 0.00120

(e) Electroplating 0.142 0.0737 0.0623 0.0478

(f) Hot Dip Coating 0.0206 0.0107 0.00903 0.00693

(g) Lubrication 0.00170 0.000884 0.000748 0.000574

(h) Mechanical

Descaling

0.000284 0.000148 0.000125 0.0000956

(i) Painting 0.00922 0.00479 0.00405 0.00311

(j) Pressure

Deformation 

0.00355 0.00184 0.00156 0.00120

Pollutant TOC TOP

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.181 0.103 0.0188 0.00896

(b) Alkaline Cleaning 0.181 0.103 0.0188 0.00896

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00901 0.00514 0.000937 0.000448

(e) Electroplating 0.361 0.206 0.0375 0.0180

(f) Hot Dip Coating 0.0523 0.0300 0.00543 0.00260

(g) Lubrication 0.00433 0.00247 0.000450 0.000215
Table 14-8 (Continued)

14.0 - Effluent Limitations and Standards

14-22

(h) Mechanical

Descaling

0.000721 0.000411 0.0000750 0.0000359

(i) Painting 0.0235 0.0134 0.00244 0.00117

(j) Pressure

Deformation 

0.00901 0.00514 0.000937 0.000448

Pollutant Cadmium Chromium

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000292 0.000188 0.000509 0.000277

(b) Alkaline Cleaning 0.000292 0.000188 0.000509 0.000277

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000146 0.00000938 0.0000255 0.0000139

(e) Electroplating 0.000583 0.000376 0.00102 0.000553

(f) Hot Dip Coating 0.0000845 0.0000545 0.000148 0.0000801

(g) Lubrication 0.00000699 0.00000450 0.0000123 0.00000663

(h) Mechanical

Descaling

0.00000116 0.00000075 0.00000204 0.00000110

(i) Painting 0.0000379 0.0000244 0.0000662 0.0000359

(j) Pressure

Deformation 

0.0000146 0.00000938 0.0000255 0.0000139

Pollutant Copper Lead

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00114 0.000565 0.0000737 0.0000522

(b) Alkaline Cleaning 0.00114 0.000565 0.0000737 0.0000522

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000570 0.0000283 0.00000368 0.00000261

(e) Electroplating 0.00228 0.00113 0.000148 0.000105
Table 14-8 (Continued)

14.0 - Effluent Limitations and Standards

14-23

(f) Hot Dip Coating 0.000331 0.000164 0.0000214 0.0000152

(g) Lubrication 0.0000274 0.0000136 0.00000177 0.00000125

(h) Mechanical

Descaling

0.00000455 0.00000226 0.00000029 0.00000021

(i) Painting 0.000148 0.0000734 0.00000957 0.00000678

(j) Pressure

Deformation 

0.0000570 0.0000283 0.00000368 0.00000261

Pollutant Manganese Molybdenum

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000269 0.000183 0.00164 0.00103

(b) Alkaline Cleaning 0.000269 0.000183 0.00164 0.00103

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000135 0.00000914 0.0000820 0.0000511

(e) Electroplating 0.000537 0.000366 0.00328 0.00205

(f) Hot Dip Coating 0.0000779 0.0000531 0.000476 0.000297

(g) Lubrication 0.00000644 0.00000439 0.0000394 0.0000246

(h) Mechanical

Descaling

0.00000107 0.00000073 0.00000656 0.00000409

(i) Painting 0.0000350 0.0000238 0.000214 0.000133

(j) Pressure

Deformation 

0.0000135 0.00000914 0.0000820 0.0000511

Pollutant Nickel Silver

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00104 0.000642 0.000456 0.000187

(b) Alkaline Cleaning 0.00104 0.000642 0.000456 0.000187

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000520 0.0000321 0.0000228 0.00000934
Table 14-8 (Continued)

14.0 - Effluent Limitations and Standards

Pollutant Nickel Silver

14-24

(e) Electroplating 0.00208 0.00129 0.000912 0.000374

(f) Hot Dip Coating 0.000302 0.000186 0.000133 0.0000542

(g) Lubrication 0.0000250 0.0000154 0.0000110 0.00000448

(h) Mechanical

Descaling

0.00000415 0.00000257 0.00000182 0.00000075

(i) Painting 0.000135 0.0000834 0.0000593 0.0000243

(j) Pressure

Deformation 

0.0000520 0.0000321 0.0000228 0.00000934

Pollutant Sulfide (as S) Tin

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0630 0.0267 0.00274 0.00139

(b) Alkaline Cleaning 0.0630 0.0267 0.00274 0.00139

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00315 0.00134 0.000137 0.0000694

(e) Electroplating 0.126 0.0534 0.00547 0.00278

(f) Hot Dip Coating 0.0183 0.00774 0.000793 0.000403

(g) Lubrication 0.00151 0.000641 0.0000656 0.0000333

(h) Mechanical

Descaling

0.000252 0.000107 0.0000110 0.00000555

(i) Painting 0.00818 0.00347 0.000356 0.000181

(j) Pressure

Deformation 

0.00315 0.00134 0.000137 0.0000694

Pollutant Zinc

Forming/Finishing Operation

Maximum Daily (lbs/1000 lbs

of product)

Maximum Monthly Avg.

(lbs/1000 lbs of product)

(a) Acid Pickling 0.000793 0.000456

(b) Alkaline Cleaning 0.000793 0.000456

(c) Cold Forming 0 0
Table 14-8 (Continued)

14.0 - Effluent Limitations and Standards

14-25

(d) Continuous Annealing 0.0000397 0.0000228

(e) Electroplating 0.00159 0.000912

(f) Hot Dip Coating 0.000230 0.000133

(g) Lubrication 0.0000191 0.0000110

(h) Mechanical Descaling 0.00000317 0.00000182

(i) Painting 0.000103 0.0000593

(j) Pressure Deformation 0.0000397 0.0000228

Pollutant Cyanide (T) Cyanide (A)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Electroplating 0.000865 0.000513 0.000580 0.000282

As explained in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either amenable

or total cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. 

14.1.6 BPT Technology Selection for the Oily Wastes Subcategory

Section 6.2.6 describes the Oily Wastes Subcategory. EPA estimates that

approximately 900 MP&M direct discharging facilities in the Oily Wastes Subcategory currently

discharge substantial quantities of pollutants to the surface waters of the United States, including

965,000 pounds per year of oil and grease, 414,00 pounds per year of TSS, 6.4 million pounds

per year of COD, 595,000 pounds per year of priority and nonconventional metal pollutants, and

135,000 pounds per year of priority and nonconventional organic pollutants. As a result of the

quantity of pollutant currently discharged directly to the nation’s waters by oily waste facilities,

EPA determined that there is a need for BPT regulation for this subcategory. 

Facilities in the Oily Wastes Subcategory generally perform unit operations such

as alkaline cleaning and its associated rinses to remove oil and dirt from components, machining

and grinding that produce wastewater containing coolants and lubricants, and dye penetrant and

magnetic flux testing that produce mainly oil-bearing wastewater (Section 6.2.6 lists the unit

operations that define the applicability of this subcategory). Because of the oily nature of the

wastewater, EPA considered technology options 5 through 8 for this subcategory. Section 9.0
14.0 - Effluent Limitations and Standards

14-26

describes the technology options. (EPA did not consider oily wastewater treatment using

dissolved air flotation (DAF) (Options 9 and 10) because it was not widely used by facilities in

this subcategory. The Agency analyzed the DAF options for the Railroad Line Maintenance and

Shipbuilding Dry Dock Subcategories only.) As explained above, EPA only discusses Options 6

and 8 in this document in detail since these options costed less and removed more pollutants than

Options 5 and 7, respectively. 

The Agency selected Option 6, oil/water separation by chemical emulsion

breaking, gravity separation, and oil skimming, as the basis for the new BPT regulation for the

Oily Wastes Subcategory. EPA's decision to propose BPT limitations on Option 6 treatment

reflects primarily two factors: (1) the degree of effluent reductions attainable and (2) the total

cost of the proposed treatment technologies in relation to the effluent reductions achieved. No

basis could be found for identifying different BPT limitations based on age, size, process, or

other engineering factors. Neither the age nor the size of a facility in the Oily Wastes

Subcategory will directly affect the treatability of MP&M process wastewater. For facilities in

this subcategory, the most pertinent factors for establishing the limitations are costs of treatment

and the level of effluent reductions obtainable.

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 6; Table 14-2 presents the cost per pound removed using only the pounds of COD

removed. EPA estimates that implementation of Option 6 will cost $2.18 per pound of COD

removed (1996 dollars). The Agency has concluded that the costs of BPT Option 6 are

achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 6 represents the average of the best

performing facilities due to the prevalence of chemical emulsion breaking and oil skimming in

this subcategory. The Agency estimates that 11 percent of the direct discharging facilities in the

Oily Wastes Subcategory perform oil/water separation through chemical emulsion breaking

(Option 6) while only 4 percent employ ultrafiltration (Option 8).

Based on the available data base, Option 8 only removes, on an annual basis, an

additional 19,000 pounds of TSS, and 56,600 pounds of oil and grease, while removing 1.42

million less pounds of COD, 12,000 less pounds of priority and nonconventional metals, and

2,400 less pounds of priority and nonconventional organic pollutants than Option 6. In addition,

Option 8's annualized cost is $43 million more than Option 6. EPA concluded that the lack of

significant overall additional pollutant removals achieved by Option 8 do not justify its use as a

basis for BPT for this subcategory. Table 14-9 lists the proposed BPT effluent limitations for the

Oily Wastes Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. EPA calculated BPT limitations for this subcategory

using data from facilities in the Oily Wastes subcategory employing Option 6 technology. 
14.0 - Effluent Limitations and Standards

14-27

Existing direct discharging facilities in the Oily Wastes Subcategory must achieve

the following effluent limitations representing the application of BPT. Discharges must remain

within the pH range 6 to 9 and must not exceed the following.

Table 14-9

BPT/BAT Effluent Limitations for the Oily Wastes Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 63 31

2. Oil and Grease (as HEM) 27 20

3. Total Organic Carbon (TOC) (as indicator) 633 378

4. Total Organics Parameter (TOP) 9.0 4.3

5. Sulfide, Total 31 13

Upon agreement with the permitting authority, facilities must choose to monitor for TOP or

TOC, or implement a management plan for organic chemicals as specified in Section 15.2.7.

14.1.7 BPT Technology Selection for the Railroad Line Maintenance Subcategory

Section 6.2.7 describes the Railroad Line Maintenance Subcategory. The Agency

estimates that there are approximately 34 direct discharging facilities in this subcategory. EPA

determined that BPT limitations for this subcategory were necessary because of the oil and grease

and potential TSS loads that facilities in this subcategory generate. EPA estimates that direct

discharging facilities in the Railroad Line Maintenance Subcategory currently discharge

substantial quantities of pollutants to the surface waters of the United States, including 52,000

pounds per year of oil and grease, 170,000 pounds per year of COD, 18,000 pounds per year of

TSS, 54,000 pounds per year of priority and nonconventional metal pollutants, and 1,600 pounds

per year of priority and nonconventional organic pollutants. As a result of the quantity of

pollutant currently discharged directly to the nation’s waters by railroad line maintenance

facilities, EPA determined that there is a need for BPT regulation for this subcategory. 

Facilities in the Railroad Line Maintenance Subcategory generally perform unit

operations that produce mainly oil-bearing wastewater, such as alkaline cleaning and its

associated rinses to remove oil and dirt from components, and machining and grinding, which

use coolants and lubricants. Because of the oily nature of the wastewater, EPA considered

technology options 7 through 10 for this subcategory. Section 9.0 describes the technology

options. EPA did not consider oily wastewater treatment using oil/water separation through

emulsion breaking (Options 5 and 6) for this subcategory because a large number of railroad line

maintenance facilities currently use DAF (Options 9 and 10). As explained above, EPA only
14.0 - Effluent Limitations and Standards

14-28

discusses Options 8 and 10 in detail in this section since these options costed less and removed

more pollutants than Options 7 and 9, respectively. 

The Agency selected Option 10, oil/water separation by DAF, as the basis for the

new BPT regulation for the Railroad Line Maintenance Subcategory. EPA's decision to propose

BPT limitations based on Option 10 treatment reflects primarily two factors: (1) the degree of

effluent reductions attainable and (2) the total cost of the proposed treatment technologies in

relation to the effluent reductions achieved. No basis could be found for identifying different

BPT limitations based on age, size, process, or other engineering factors. Neither the age nor the

size of a facility in the Railroad Line Maintenance Subcategory will directly affect the treatability

of MP&M process wastewater. For facilities in this subcategory, the most pertinent factors for

establishing the limitations are costs of treatment and the level of effluent reductions obtainable.

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 10; Table 14-2 presents the cost per pound removed using only the pounds of oil and

grease removed. EPA estimates that implementation of Option 10 will cost $20.00 per pound of

COD removed (1996 dollars). The Agency has concluded that the costs of BPT Option 10 are

achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 10 represents the average of the best

performing facilities due to the prevalence of DAF in this subcategory. The Agency estimates

that 91 percent of the direct discharging facilities in the Railroad Line Maintenance Subcategory

employ DAF (Option 10), while no facilities employ ultrafiltration (Option 8). Because no

facilities in this subcategory employ ultrafiltration to remove oil and grease, the Agency

concluded that Option 8 does not represent BPT. Table 14-10 lists the proposed BPT effluent

limitations for the Railroad Line Maintenance Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. EPA calculated BPT limitations for this subcategory

using data from facilities in the Railroad Line Maintenance subcategory employing Option 10

technology. In cases where data from the Railroad Line Maintenance subcategory was not

sufficient for a particular pollutant, the Agency transferred effluent data from facilities in the

Shipbuilding Dry Dock subcategory in order to develop a proposed BPT limitation. 

Existing direct discharging facilities in the Railroad Line Maintenance

Subcategory must achieve the following effluent limitations representing the application of BPT. 

Discharges must remain within the pH range 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-29

Table 14-10

BPT Effluent Limitations for the Railroad Line Maintenance Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg.

(mg/L (ppm))

1. BOD5 34 12

2. Total Suspended Solids (TSS) 30 16

3. Oil and Grease (as HEM) 11 8

14.1.8 BPT Technology Selection for the Shipbuilding Dry Dock Subcategory

Section 6.2.8 describes the Shipbuilding Dry Dock Subcategory. The Agency

estimates there are six direct discharging facilities in this subcategory. The Agency notes that

many shipbuilders operate multiple dry docks (or similar structures) and that this is the number

of estimated facilities (not dry docks) that discharge MP&M process wastewater from dry docks

(and similar structures). EPA determined that BPT limitations for this subcategory were

necessary because of the oil and grease and potential TSS loads that facilities in this subcategory

generate. EPA estimates that direct discharging facilities in the Shipbuilding Dry Dock

Subcategory currently discharge substantial quantities of pollutants to the surface waters of the

United States, including 8.5 million pounds per year of oil and grease, 18,400 pounds per year of

TSS, 976,000 pounds per year of COD, 88,500 pounds per year of priority and nonconventional

metal pollutants, and 6,000 pounds per year of priority and nonconventional organic pollutants. 

As a result of the quantity of pollutants currently discharged directly to the nation’s waters by

shipbuilding dry dock facilities, EPA determined that there is a need for BPT regulation for this

subcategory. 

Facilities in the Shipbuilding Dry Dock Subcategory generally perform unit

operations that produce mainly oil-bearing wastewater, such as abrasive blasting, hydroblasting,

painting, welding, corrosion preventive coating, floor cleaning, aqueous degreasing, and testing

(e.g., hydrostatic testing). Because of the oily nature of the wastewater, EPA considered

technology options 7 through 10 for this subcategory. Section 9.0 describes the technology

options. EPA did not consider oily wastewater treatment using oil/water separation through

chemical emulsion breaking (Options 5 and 6) for this subcategory because all of the

shipbuilding dry dock facilities in EPA’s database currently use DAF (Options 9 and 10). As

explained above, EPA only discusses Options 8 and 10 in detail in this section since these

options costed less and removed more pollutants than Options 7 and 9, respectively.

 

The Agency selected Option 10, oil/water separation by DAF, as the basis for the

new BPT regulation for the Shipbuilding Dry Dock Subcategory. EPA's decision to propose

BPT limitations based on Option 10 treatment reflects primarily two factors: (1) the degree of
14.0 - Effluent Limitations and Standards

14-30

effluent reductions attainable and (2) the total cost of the proposed treatment technologies in

relation to the effluent reductions achieved. No basis could be found for identifying different

BPT limitations based on age, size, process, or other engineering factors. Neither the age nor the

size of a facility in the Shipbuilding Dry Dock Subcategory will directly affect the treatability of

MP&M process wastewater. For facilities in this subcategory, the most pertinent factors for

establishing the limitations are costs of treatment and the level of effluent reductions obtainable.

Table 14-1 presents the annual pollutant removals for direct dischargers for

Option 10; Table 14-2 presents the cost per pound removed using only the pounds of oil and

grease removed. EPA estimates that implementation of Option 10 will cost $0.25 per pound of

oil and grease removed (1996 dollars). The Agency has concluded that the costs of BPT Option

10 are achievable and are reasonable as compared to the removals achieved by this option.

The technology proposed in Option 10 represents the average of the best

performing facilities due to the prevalence of DAF in this subcategory. According to EPA’s

database, 100 percent of the direct discharging facilities in the Shipbuilding Dry Dock

Subcategory employ DAF (Option 10) while no facilities employ ultrafiltration (Option 8). 

Because no facilities in this subcategory employ ultrafiltration to remove oil and grease, the

Agency concluded that Option 8 does not represent best practicable control technology. Table

14-11 lists the proposed BPT effluent limitations for the Shipbuilding Dry Docks Subcategory. 

EPA’s data editing procedures and statistical methodology for calculating BPT

limitations are explained in Section 10.0. EPA calculated BPT limitations for this subcategory

using data from facilities in the Shipbuilding Dry Dock subcategory employing Option 10

technology. 

Existing direct discharging facilities in the Shipbuilding Dry Dock Subcategory

must achieve the following effluent limitations representing the application of BPT. Discharges

must remain within the pH range 6 to 9 and must not exceed the following.

Table 14-11

BPT Effluent Limitations for the Shipbuilding Dry Dock Subcategory

Regulated Parameter

Maximum

Daily1

Maximum

Monthly 

Avg.1

1. Total Suspended Solids (TSS) 81 44

2. Oil and Grease (as HEM) 16 11
14.0 - Effluent Limitations and Standards

14-31

14.2 Best Conventional Pollutant Control Technology (BCT)

The BCT methodology, promulgated in 1986 (51 FR 24974), discusses the

Agency's consideration of costs in establishing BCT effluent limitations guidelines. EPA

evaluates the reasonableness of BCT candidate technologies (those that are technologically

feasible) by applying a two-part cost test:

(1) The POTW test; and

(2) The industry cost-effectiveness test.

In the POTW test, EPA calculates the cost per pound of conventional pollutant

removed by industrial dischargers in upgrading from BPT to a BCT candidate technology and

then compares this cost to the cost per pound of conventional pollutant removed in upgrading

POTWs from secondary treatment. The upgrade cost to industry must be less than the POTW

benchmark of $0.25 per pound (in 1976 dollars).

In the industry cost-effectiveness test, the ratio of the incremental BPT to BCT

cost divided by the BPT cost for the industry must be less than 1.29 (i.e., the cost increase must

be less than 29 percent).

14.2.1 BCT Option for Metal-Bearing Wastewater

For the MP&M proposed rule, EPA considered whether or not to establish BCT

effluent limitations guidelines for MP&M sites that would attain incremental levels of effluent

reduction beyond BPT for TSS. The only technology option identified to attain further TSS

reduction is the addition of multimedia filtration to existing BPT systems. For the BCT option,

EPA considered adding multimedia filtration to the BPT technology option for the General

Metals, Metal Finishing Job Shops, Non-Chromium Anodizing, Printed Wiring Board, and Steel

Forming and Finishing Subcategories (i.e., the metal-bearing subcategories). 

EPA applied the BCT cost test to the use of multimedia filtration technology as a

means to reduce TSS loadings. EPA split the MP&M sites into three flow categories: less than

10,000 gallons per year (gpy)), 10,000 gpy and 1,000,000 gpy; and greater than 1,000,000 gpy. 

For each of these three flow categories, EPA chose a representative site for which EPA had

estimated the costs of installing the Option 2 technologies discussed under BPT (see Section 14.1

above). The Agency evaluated the costs of installing a polishing multimedia filter to remove an

estimated additional 35 percent of the TSS discharged after chemical precipitation and

clarification treatment. This estimated removal reflects the reduced TSS concentrations seen

when filters are used after chemical precipitation and sedimentation in the MP&M industry. The

cost per pound removed for facilities discharging greater than 1 million gallons per year

(1 MGY) was $13/lb of TSS (in 1976 dollars), the cost per pound removed for facilities

discharging between 10,000 and 1,000,000 gpy was $518/lb, and the cost per pound removed for

facilities discharging less than 10,000 gpy was $1,926/lb of TSS (in 1976 dollars). All of these

cases individually as well as combined exceed the $0.25/lb (in 1976 dollars) POTW cost test
14.0 - Effluent Limitations and Standards

14-32

value. Because these costs exceed the POTW benchmark, the first part of the cost test fails;

therefore, the second part of the test was unnecessary. As a result, EPA determined that

multimedia filtration does not pass the cost test for BCT regulations development. In light of the

above, EPA is proposing to set BCT limitations for the General Metals, Metal Finishing Job

Shops, Non-Chromium Anodizing, Printed Wiring Board, and Steel Forming and Finishing

Subcategories equivalent to BPT limitations for their respective subcategories.

14.2.2 BCT Option for Oil-Bearing Wastewater

For the MP&M proposed rule, EPA considered whether or not to establish BCT

effluent limitations guidelines for MP&M facilities that would attain incremental levels of

effluent reduction beyond BPT for oil and grease. EPA considered adding an ultrafilter to

existing BPT systems (oil/water separation by chemical emulsion breaking, gravity separation,

and oil skimming) as a viable technology option to attain further oil and grease reduction. EPA

considered this BCT option for the Oily Wastes, Railroad Line Maintenance, and Shipbuilding

Dry Dock Subcategories.

EPA applied the BCT cost test to the use of ultrafiltration technology as a means

to reduce oil and grease loadings. EPA split the MP&M sites into three flow categories: less than

10,000 gpy, 10,000 gpy to 1,000,000 gpy; and greater than 1,000,000 gpy. For each of these

three flow categories, EPA chose a representative site for which EPA had estimated the costs of

installing the Option 2 technologies discussed under BPT (See Section 14.1 above). The Agency

evaluated the costs of installing an ultrafilter to remove an estimated additional 36 percent of the

oil and grease discharged after oil/water separation by chemical emulsion breaking, gravity

separation, and oil skimming. This estimated removal reflects the reduced oil and grease

concentrations seen when ultrafilters are used after chemical emulsion breaking with oil

skimming in the MP&M industry. The cost per pound removed for facilities discharging greater

than 1 MGY was $238/lb of oil and grease (in 1976 dollars), the cost per pound removed for

facilities discharging between 10,000 and 1 MGY was $2,213/lb, and the cost per pound

removed for facilities discharging less than 10,000 gpy was $5,031/lb of oil and grease (in 1976

dollars). All of these cases individually as well as combined exceed the $0.25/lb (in 1976

dollars) POTW cost test value. Because these costs exceed the POTW benchmark, the first part

of the cost test fails; therefore, the second part of the test was unnecessary. Therefore, EPA

determined that ultrafiltration does not pass the cost test for BCT regulations development. In

light of the above, EPA is proposing to set BCT limitations for the Oily Wastes, Railroad Line

Maintenance and Shipbuilding Dry Dock Subcategories equivalent to BPT limitations for their

respective subcategories.

14.3 Best Available Technology Economically Achievable (BAT)

EPA considers the following factors in establishing the best available technology

economically achievable (BAT) level of control: the age of process equipment and facilities, the

processes employed, process changes, the engineering aspects of applying various types of

control techniques, the costs of applying the control technology, economic impacts imposed by
14.0 - Effluent Limitations and Standards

14-33

the regulation, non-water quality environmental impacts such as energy requirements, air

pollution, and solid waste generation, and other such factors as the Administrator deems

appropriate (section 304(b)(2)(B) of CWA). In general, the BAT technology level represents the

best existing economically achievable performance among plants with shared characteristics. In

making the determination about economic achievability, the Agency takes into consideration

factors such as plant closures and product line closures. Where existing wastewater treatment

performance is uniformly inadequate, BAT technology may be transferred from a different

subcategory or industrial category. BAT may also include process changes or internal plant

controls that are not common industry practice.

 EPA considered the same 10 technology options for BAT as discussed under

BPT. EPA did not include the application of filters, discussed under BCT, as a BAT option. 

Data collected during sampling at MP&M facilities demonstrated very little, if any, additional

removal of many metal pollutants resulting from the use of filters as compared to concentrations

of the same metals after the chemical precipitation and clarification treatment followed by gravity

settling. Thus, although filtration is demonstrated to be effective in achieving additional

removals of suspended solids and, as such, EPA considered it for the basis of BCT, multimedia

or sand filtration does not reflect the best available technology performance for priority and

nonconventional pollutants. 

For all of the MP&M subcategories (except the Railroad Line Maintenance and

Shipbuilding Dry Dock Subcategories), EPA is proposing BAT limitations equivalent to BPT. 

For the Railroad Line Maintenance and Shipbuilding Dry Dock subcategories, EPA is not

proposing BAT limitations. EPA briefly discusses the BAT selection for each of the

subcategories in Sections 14.3.1 through 14.3.8.

14.3.1 BAT Technology Selection for the General Metals Subcategory

EPA has not identified any more stringent economically achievable treatment

technology option that it considered to represent BAT level of control applicable to General

Metals Subcategory facilities. Therefore, the Agency is proposing to establish BAT equivalent to

BPT for toxic and nonconventional pollutants for the General Metals Subcategory. EPA

estimates that 20 facilities (less than 1 percent of the direct dischargers in this subcategory) will

close as a result of BAT based on Option 2. EPA found this option to be economically

achievable for the subcategory as a whole. Additionally, the Agency believes that Option 2

represents the “best available” technology as it achieves a high level of pollutant control, treating

all priority pollutants to very low levels, often at or near the analytical minimum level. 

EPA did evaluate BPT Option 4 as a basis for establishing BAT more stringent

than the BPT level of control being proposed. EPA estimates that the economic impact due to

the additional controls at Option 4 levels would result in 35 facility closures (<1 percent of the

direct dischargers in this subcategory). The Economic, Environmental, and Benefits Analysis of

the Proposed Metal Products & Machinery Rule [EPA-821-B-00-0058] discusses job losses. 

While EPA does not have a bright line for determining what level of impact is economically
14.0 - Effluent Limitations and Standards

14-34

achievable for the industry as a whole, EPA looked for a breakpoint that would mitigate adverse

economic impacts without greatly affecting the toxic pound-equivalents being removed under the

proposed rule. By selecting Option 2 as BAT, EPA was able to reduce facility closures by 43

percent, while only losing about 1.5 percent of the toxic pound equivalents that would be

removed under Option 4. Option 4 resulted in some level of improved pollutant reductions;

however, the amounts are not very large and the cost of implementing the level of control

associated with Option 4 is disproportionately high. Thus, EPA rejected Option 4 as a basis for

BAT for this subcategory. 

14.3.2 BAT Technology Selection for the Metal Finishing Job Shops Subcategory

The Agency proposes to establish BAT equivalent to BPT for toxic and

nonconventional pollutants for the Metal Finishing Job Shops Subcategory. EPA estimates that

no facilities will close as a result of BAT based on Option 2. Therefore, the Agency found this

option to be economically achievable. Additionally, the Agency believes that Option 2

represents the “best available” technology as it achieves a high level of pollutant control, treating

all priority pollutants to very low levels, often at or near the analytical minimum level. 

EPA did evaluate transferring technology reflected in BPT Option 4 as a basis for

establishing BAT more stringent than the BPT level of control being proposed. As was the case

for BAT based on Option 2, EPA estimates that no facilities will close as a result of BAT based

on Option 4. Therefore, EPA does consider Option 4 to be economically achievable for this

subcategory. However, EPA is not proposing to establish BAT limitations based on Option 4

because it determined that Option 2 achieves nearly equivalent reductions in pound-equivalents

for much less cost. By selecting Option 2 as the basis for BAT, EPA reduced annualized

compliance costs by $1.1 million (1996 dollars) while only losing 2 percent of the toxic poundequivalents that would be removed under Option 4. The Agency concluded that the additional

costs of Option 4 do not justify the lack of significant additional pollutant removals achieved for

direct dischargers in this subcategory. Therefore, EPA determined that Option 2 is the “best

available” technology economically achievable for the Metal Finishing Job Shops Subcategory. 

14.3.3 BAT Technology Selection for the Non-Chromium Anodizing Subcategory

The Agency proposes to establish BAT equivalent to BPT for toxic and

nonconventional pollutants for the Non-Chromium Anodizing Subcategory. As mentioned in

the BPT discussion, EPA’s survey of the MP&M industry did not identify any non-chromium

anodizing facilities discharging directly to surface waters. All of the non-chromium anodizing

facilities in EPA’s data base are either indirect or zero dischargers. EPA consequently could not

evaluate any treatment systems in place at direct discharging non-chromium anodizing facilities

for establishing BAT limitations. Therefore, EPA relied on information and data from indirect

discharging facilities in the Non-Chromium Anodizing Subcategory. Based on this analysis, the

Agency believes that Option 2 represents the “best available” technology as it achieves a high

level of pollutant control, treating all priority pollutants to very low levels, often at or near the

analytical minimum level. 
14.0 - Effluent Limitations and Standards

14-35

EPA evaluated transferring technology reflected in BPT Option 4 as a basis for

establishing BAT more stringent than the BPT level of control being proposed. However, EPA is

not proposing to establish BAT limitations based on Option 4 because it determined that Option

2 achieves nearly equivalent reductions in pound-equivalents for much less cost. EPA used a

facility with a flow of 6.25 MGY (the median discharge flow for indirect discharging facilities in

this subcategory) to model the costs and pollutant loads reduction for a direct discharging facility. 

Because direct dischargers are more likely to have treatment in place, EPA provided the model

facility with treatment in place equivalent to Option 1. Based on this model facility, EPA

estimated that annualized compliance costs per facility for Option 2 will be $41,000 (1996

dollars) less than Option 4, and Option 2 will remove only 83 pound-equivalents less than Option

4. The Agency concluded that the additional costs of Option 4 do not justify the additional

pollutant removals achieved for direct dischargers in this subcategory. Therefore, EPA

determined that Option 2 is the “best available” technology economically achievable for the NonChromium Anodizing Subcategory. 

14.3.4 BAT Technology Selection for the Printed Wiring Board Subcategory

The Agency proposes establishing BAT equivalent to BPT for toxic and

nonconventional pollutants for the Printed Wiring Board Subcategory. EPA estimates that no

facilities will close as a result of BAT based on Option 2. Therefore, the Agency found this

option to be economically achievable. Additionally, the Agency believes that Option 2

represents the “best available” technology as it achieves a high level of pollutant control, treating

all priority pollutants to very low levels, often at or near the analytical minimum level. 

EPA evaluated BPT Option 4 as a basis for establishing BAT more stringent than

the BPT level of control being proposed. As was the case for BAT based on Option 2, EPA

estimates that no facilities will close as a result of BAT based on Option 4. Therefore, EPA

considers Option 4 to be economically achievable for this subcategory. However, EPA is not

proposing to establish BAT limitations based on Option 4 because it determined that Option 2

achieves nearly equivalent reductions in pound-equivalents for much less cost. By selecting

Option 2 as the basis for BAT, EPA reduced annualized compliance costs by $2 million (1996

dollars) while only losing 3 percent of the toxic pound-equivalents that would be removed under

Option 4. The Agency concluded that the additional costs of Option 4 do not justify the lack of

significant additional pollutant removals achieved for direct dischargers in this subcategory.

Therefore, EPA determined that Option 2 is the “best available” technology economically

achievable for the Printed Wiring Board Subcategory. 

14.3.5 BAT Technology Selection for the Steel Forming and Finishing Subcategory

The Agency proposes establishing BAT equivalent to BPT for toxic and

nonconventional pollutants for the Steel Forming and Finishing Subcategory. EPA estimates that

no facilities will close as a result of BAT based on Option 2. Therefore, the Agency found this

option to be economically achievable. Additionally, the Agency believes that Option 2
14.0 - Effluent Limitations and Standards

14-36

represents the “best available” technology as it achieves a high level of pollutant control, treating

all priority pollutants to very low levels, often at or near the analytical minimum level. 

EPA evaluated transferring technology reflected in BPT Option 4 as a basis for

establishing BAT more stringent than the BPT level of control being proposed. EPA is not

proposing to establish BAT limitations based on Option 4 because it determined that Option 2

achieves nearly equivalent reductions in pound-equivalents for much less cost. By selecting

Option 2 as the basis for BAT, EPA reduced annualized compliance costs by $2.6 million (1996

dollars) while only losing 3 percent of the toxic pound-equivalents that would be removed under

Option 4. The Agency concluded that the additional costs of Option 4 do not justify the

insignificant additional pollutant removals achieved for direct dischargers in this subcategory.

14.3.6 BAT Technology Selection for the Oily Wastes Subcategory

EPA has not identified any more stringent economically achievable treatment

technology option that it considered to represent BAT level of control applicable to Oily Wastes

Subcategory facilities. Therefore, the Agency is proposing to establish BAT equivalent to BPT

for toxic and nonconventional pollutants for the Oily Wastes Subcategory. EPA estimates that

no facilities will close as a result of BAT based on Option 6. Additionally, the Agency believes

that Option 6 represents the “best available” technology as it achieves a high level of pollutant

control, treating all priority pollutants to very low levels, often at or near the analytical minimum

level. 

EPA evaluated BPT Option 8 (ultrafiltration) as a basis for establishing BAT

more stringent than the BPT level of control being proposed. As was the case for BAT based on

Option 6, EPA estimates that no facilities would close as a result of BAT based on Option 8. 

Therefore, EPA does consider Option 8 to be economically achievable for this subcategory. 

However, based on the available data base, EPA is not proposing to establish BAT limitations

based on Option 8 because it removes fewer pound-equivalents than Option 6. Therefore, the

Agency determined that Option 6 is the “best available” technology economically achievable for

the removal of priority pollutants from wastewater generated at Oily Wastes Subcategory

facilities. 

14.3.7 BAT Technology Selection for the Railroad Line Maintenance Subcategory

EPA is not proposing to establish BAT regulations for the Railroad Line

Maintenance Subcategory. The Agency concluded that the facilities in this subcategory

discharge very few pounds of toxic pollutants. EPA estimates that 34 railroad line maintenance

facilities discharge 1,100 pound-equivalents per year to surface waters, or about 32 poundequivalents per year per facility. The Agency based the loadings calculations on EPA sampling

data, which found very few priority toxic pollutants at treatable levels in raw wastewater. 

Therefore, nationally-applicable regulations are unnecessary at this time and direct dischargers

will remain subject to permit limitations for toxic and nonconventional pollutants established on

a case-by-case basis using best professional judgement.
14.0 - Effluent Limitations and Standards

14-37

14.3.8 BAT Technology Selection for the Shipbuilding Dry Dock Subcategory

EPA is not proposing to establish BAT regulations for the Shipbuilding Dry Dock

Subcategory because of the small number of facilities in this subcategory. EPA estimates there

are six shipbuilding facilities operating one or more dry docks in the U.S. that discharge directly

to surface waters. EPA determined that nationally applicable regulations are unnecessary at this

time because of the small number of facilities in this subcategory. The Agency believes that

limitations established on a case-by-case basis using best professional judgement can more

appropriately address individual toxic and nonconventional pollutants that may be present at

these six facilities.

 

14.4 Pretreatment Standards for Existing Sources (PSES)

Indirect dischargers in the MP&M industrial category, like the direct dischargers,

use raw materials that contain many priority pollutant and nonconventional metal pollutants. 

These indirect discharging facilities may discharge many of these pollutants to POTWs at

significant mass or concentration levels, or both. EPA estimates that indirect discharging

facilities annually discharge approximately 125 million pounds of priority and nonconventional

metals, and 47 million pounds of priority and nonconventional organic pollutants.

Unlike direct dischargers whose wastewater will receive no further treatment once

it leaves the facility, indirect dischargers send their wastewater to POTWs for further treatment

(unless there is a bypass, upset, or sewer overflow). EPA establishes pretreatment standards for

those BAT pollutants that pass through POTWs. Therefore, for indirect dischargers, before

proposing pretreatment standards, EPA examines whether the pollutants discharged by the

industry “pass through” POTWs to waters of the U.S. or interfere with POTW operations or

sludge disposal practices on a national basis. Generally, to determine if pollutants pass through

POTWs, EPA compares the percentage of the pollutant removed by well-operated POTWs

achieving secondary treatment with the percentage of the pollutant removed by facilities meeting

BAT effluent limitations. In this manner, EPA can ensure that the combined treatment at indirect

discharging facilities and POTWs is at least equivalent to that obtained through treatment by

direct dischargers.

This approach to the definition of pass-through satisfies two competing objectives

set by Congress: (1) that standards for indirect dischargers be equivalent to standards for direct

dischargers, and (2) that the treatment capability and performance of POTWs be recognized and

taken into account in regulating the discharge of pollutants from indirect dischargers. Rather

than compare the mass or concentration of pollutants discharged by POTWs with the mass or

concentration of pollutants discharged by BAT facilities, EPA compares the percentage of the

pollutants removed by BAT facilities to the POTW removals. EPA takes this approach because a

comparison of the mass or concentration of pollutants in POTW effluents with pollutants in BAT

facility effluents would not take into account the mass of pollutants discharged to the POTW

from other industrial and nonindustrial sources, nor the dilution of the pollutants in the POTW to
14.0 - Effluent Limitations and Standards

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lower concentrations from the addition of large amounts of other industrial and nonindustrial

water.

The primary source of the POTW percent removal data is the Fate of Priority

Pollutants in Publicly Owned Treatment Works (EPA 440/1-82/303, September 1982),

commonly referred to as the “50-POTW Study.” This study presents data on the performance of

50 well-operated POTWs that employ secondary biological treatment in removing pollutants. 

Each sample was analyzed for three conventional, 16 nonconventional, and 126 priority toxic

pollutants. 

Section 7.0 discusses the results of the POTW pass-through analysis for indirect

dischargers for each subcategory. The appendix to Section 7.0 discusses additional revisions that

the Agency is considering to the editing criteria applied to the 50-POTW database. 

14.4.1 Overview of Options and Low-Flow Exclusions 

Indirect discharging MP&M facilities generate wastewater with similar pollutant

characteristics to direct discharging facilities. Therefore, in evaluating technology options for

PSES, EPA considered the same 10 treatment technologies discussed previously for BPT and

BAT. However, as described below, along with the technology options, EPA also evaluated

“low flow” exclusions for indirect discharging facilities.

For each subcategory, EPA evaluated various low-flow exclusions (also referred

to as “flow cutoffs”) for indirect dischargers. The Agency considered several factors in

determining what flow level, if any, is appropriate for excluding facilities from compliance with

pretreatment standards. For several of the subcategories, EPA considered the local control

authorities’ increased burden associated with the development of new permits or other control

mechanisms for MP&M facilities. For some subcategories, the Agency considered flow

exclusions as a way to reduce economic impacts. The Economic, Environmental, and Benefits

Analysis of the Proposed Metal Products & Machinery Rule [EPA-821-B-00-0058] discusses job

losses. EPA also considered the amount of pollutants (in pound-equivalents) discharged per year

by the subcategory and by each of the facilities on an average annual basis in conjunction with

the costs of regulation, to identify an appropriate level for an exclusion. In cases where EPA

selected an option that also specifies a flow cutoff, it means that facilities with annual wastewater

flow below the cutoff would not be subject to the MP&M categorical pretreatment standards. 

These facilities would remain subject to the general pretreatment regulation at 40 CFR 403. 

Some of these options would require excluded facilities to remain covered by categorical

pretreatment standards under 40 CFR 413 (Electroplating) and 40 CFR 433 (Metal Finishing). In

addition, some indirect discharging facilities in the General Metals Subcategory that discharge

less than 1 MGY will remain covered by the pretreatment standards in 40 CFR 433. EPA is not

proposing pretreatment standards for the Non-Chromium Anodizing Subcategory. Therefore, all

indirect discharging facilities in this subcategory will remain subject to the applicable

pretreatment standards in 40 CFR 413 or 40 CFR 433. 
14.0 - Effluent Limitations and Standards

14-39

Table 14-12 summarizes the pounds of pollutants removed by the proposed

options for indirect dischargers in each subcategory, and Table 14-13 summarizes the costs and

economic impacts associated with the proposed options for indirect dischargers in each

subcategory with proposed standards. EPA is not proposing pretreatment standards for the NonChromium Anodizing, Railroad Line Maintenance, and Shipbuilding Dry Dock Subcategories for

the reasons described later in this section. (See Section 14.1 for summary tables for direct

dischargers). Section 10.0 describes EPA’s data editing procedures and statistical methodology

for calculating the proposed effluent limits.

Table 14-12

Annual Pounds of Pollutants Removed by the Proposed PSES Option for

Indirect Dischargers by Subcategory

Subcategory

(Number of Facilities)

Selected Option

(Flow Cutoff)

Priority and

Nonconventional

Metals

(lbs-removed/yr) 

Priority and

Nonconventional

Organics (lbsremoved/yr) Cyanide

(lbs-removed/yr) 

General Metals (3,055) Option 2

(1 MGY)

28.1 million 7.7 million 284,000

Metal Finishing Job Shops

(1,514)

Option 2 2.4 million 47,000 1 million

Printed Wiring Boards

(621)

Option 2 2.6 million 14,000 230,000

Steel Forming and

Finishing (110)

Option 2 617,000 16,000 181

Oily Waste (226) Option 6

(2 MGY)

191,000 1.1 million 0
14.0 - Effluent Limitations and Standards

14-40

Table 14-13

Annual Costs and Economic Impacts of the Proposed PSES Option for

Indirect Dischargers by Subcategory

Subcategory

(Number of Facilities)

Selected Option

(Flow Cutoff)

Annualized

Compliance Costs for

Selected Option

(1996 $) 

Economic Impacts

(Facility Closures) of

Selected Option

(Percentage of

Regulated

Subcategorya)

General Metals (3,055) Option 2

(1 MGY)

1.57 billion 24 (<1%)

Metal Finishing Job Shops

(1,514)

Option 2 178 million 128 (10%)

Printed Wiring Boards

(621)

Option 2 147 million 7 (1%)

Steel Forming and

Finishing (110)

Option 2 24 million 6 (6%)

Oily Waste (226) Option 6

(2 MGY)

10 million 14 (<1%)

a

 Baseline closures will not be regulated and, therefore, are not included when estimating the percentage of

regulatory closures (% regulatory closures = the regulatory closures/all facilities in subcategory excluding baseline

closures).

14.4.2 PSES for General Metals Subcategory

As discussed in Section 14.4, one of the factors that EPA uses to determine the

need for pretreatment standards is whether the pollutants discharged by an industry pass through

a POTW. The Agency only applied the pass-through analysis to pollutants that it selected for

regulation under BAT. For the General Metals Subcategory, EPA determined that 13 pollutants

pass through; therefore, EPA proposes pretreatment standards equivalent to BAT for these

pollutants. In addition, EPA is proposing a standard for total sulfide based on potential POTW

interference or upset associated with discharges of total sulfide from MP&M facilities. EPA is

also proposing standards for TOC and TOP as part of a compliance alternative for organic

pollutant discharges. (See Section 7 for a more detailed discussion of the pass-through analysis).

As discussed in Section 14.4.1, in the Agency's engineering assessment of the best

available technology for pretreatment of wastewater from the General Metals Subcategory, EPA

considered the same technology options for PSES as it did for BAT with the additional

consideration of a flow cutoff. The Agency selected BAT Option 2 with a 1 MGY flow cutoff

for PSES. EPA selected Option 2 for many of the same reasons it selected that option for BPT

and BAT (See Sections 14.1.1 and 14.3.1) and provides additional rationale below.
14.0 - Effluent Limitations and Standards

14-41

EPA determined that Option 2 represented the best available technology and that

Option 2 with a 1 MGY flow cutoff was economically achievable and greatly reduced the burden

on POTWs. This option results in 24 facility closures (less than 1 percent of the indirect

discharging General Metals Subcategory population). Additionally, the Agency believes that

Option 2 represents the “best available” technology as it achieves a high level of pollutant

control, treating all priority pollutants to very low levels, often at or near the analytical minimum

level. Approximately 15 percent of the indirect discharging facilities in the General Metals

Subcategory employ chemical precipitation followed by a sedimentation (Option 2) while 1

percent employ microfiltration after chemical precipitation (Option 4). 

EPA did evaluate Option 4 with a 1 MGY flow cutoff as a basis for establishing

PSES. EPA estimates that the economic impact due to the additional controls at Option 4 levels

would result in 92 facility closures (less than 1 percent of the indirect dischargers in this

subcategory). While EPA does not have a bright line for determining what level of impact is

economically achievable for the industry as a whole, EPA looked for a breakpoint that would

mitigate adverse economic impacts without greatly affecting the toxic pound-equivalents being

removed under the proposed rule. By selecting Option 2 as PSES, EPA was able to reduce

facility closures by more than two-thirds, while losing only a little over one percent of the toxic

pound-equivalents from control under Option 4. The Agency concluded that the additional

facility closures associated with Option 4 do not justify the insignificant additional pollutant

removals achieved for indirect dischargers in this subcategory.

Considering the large number of indirect dischargers in the General Metals

Subcategory that have the potential to be covered by this proposed regulation, an important issue

to the affected industry and to permit writers is the potentially enormous administrative burden

associated with issuing permits or other control mechanisms for all of these facilities. Therefore,

in developing this proposal, EPA has looked for means of reducing the administrative burden,

monitoring requirements, and reporting requirements. To meet this end, the Agency is proposing

a 1 MGY flow cutoff for the General Metals Subcategory. Under this proposed option, facilities

in the General Metals Subcategory that discharge greater than 1 MGY of MP&M process

wastewater would be subject to the proposed categorical pretreatment standards. Facilities in the

General Metals Subcategory that discharge 1 MGY or less would not be subject to MP&M PSES

requirements. However, some of the facilities in this subcategory discharging under 1 MGY are

currently covered by 40 CFR 433, Metal Finishing PSES or PSNS, and would remain subject to

those pretreatment standards and the general pretreatment standards at 40 CFR 403.

The Agency determined that the 1 MGY flow cutoff was appropriate for the

General Metals Subcategory based on several factors. First, and the most important factor, was

the overall size of the General Metals Subcategory. EPA estimates that there are over 26,000

indirect discharging facilities in the General Metals Subcategory, of which 74 percent are not

currently regulated by nationally established effluent guidelines. Establishing an MP&M

pretreatment standard for all 26,000 facilities would greatly increase the number of permits or

other control mechanisms for which local authorities are currently responsible (EPA estimates

that there are approximately 30,000 control mechanisms today). EPA concluded that this
14.0 - Effluent Limitations and Standards

14-42

increased permit burden was not reasonable and therefore explored potential flow cutoffs as a

way to reduce the impact on POTW permitting authorities. 

Second, EPA is proposing the 1 MGY flow cutoff for this subcategory based in

part on the small number of pound-equivalents that would be removed by facilities with annual

wastewater flows less than or equal to 1 MGY. EPA determined that 89 percent of the indirect

discharging facilities in the General Metals Subcategory discharge less than or equal to 1 MGY,

yet these facilities are responsible for less than 6 percent of the total pound-equivalents currently

discharged. If the Agency proposed pretreatment standards for facilities in the General Metals

Subcategory that discharged less than or equal to 1 MGY, it estimates average removals of only

22 pound-equivalents per facility per year for those facilities. EPA recently decided not to

promulgate pretreatment standards for two industrial categories, Industrial Laundries (64 FR

45072) and Landfills (65 FR 3008), based on low removals of toxic pound-equivalents by

facilities in those categories. In the Industrial Laundries rule, EPA decided not to promulgate

pretreatment standards based on 32 toxic pound-equivalents per facility per year, and, in the

landfills effluent guidelines, EPA decided not to promulgate pretreatment standards for

nonhazardous landfills based on the removal of only 14 toxic pound-equivalents per facility per

year. In both instances, the Agency considered that the small additional removals that would be

achieved through regulation did not warrant adoption of national categorical standards. 

The Agency concluded that regulation of facilities discharging only 22 poundequivalents per year was not justified by the additional permitting burden associated with these

facilities. Although this decision is based upon a subset of small facilities, and not an entire

subcategory as was done before, EPA believes this approach would allow control authorities to

focus their efforts on the facilities discharging the vast majority of the pollutants, rather than

dissipating their limited resources on sites contributing much less to the overall problem. EPA

acknowledges that this may create an economic advantage for the smaller facilities, and solicited

comment in the proposal on this exclusion.

EPA also closely evaluated Option 2 with a 2 MGY flow cutoff for the General

Metals Subcategory. The Agency is not proposing this option because it does not reduce the

number of facility closures (24) or significantly reduce the burden on control authorities. There

is also a significant number of pound-equivalents associated with facilities discharging between 1

and 2 MGY. EPA determined that only 3 percent more of the facilities in this subcategory

discharge between 1 and 2 MGY. This small number of facilities accounts for an additional 13

percent of the annual pollutant discharge load (in pound-equivalents). If EPA proposed Option 2

with a 2 MGY flow cutoff, the economic impacts would not be reduced. Based on these

considerations, EPA is not proposing the 2 MGY flow cutoff for the General Metals

Subcategory. EPA concluded that the 1 MGY flow cutoff was the most appropriate option in

terms of balancing POTW burden reduction with pollutant removals and mitigating economic

impacts. Table 14-12 shows the pounds of pollutants removed by the proposed option; Table 14-

13 summarizes the costs and economic impacts associated with the proposed option. Table 14-

14 lists the proposed PSES for the General Metals Subcategory. Where these General Metals

facilities discharge less than or equal to 1 MGY to a POTW, these proposed pretreatment
14.0 - Effluent Limitations and Standards

14-43

standards do not apply; however, facilities are still subject to other applicable pretreatment

standards, including those established under parts 413 and 433. Section 10.0 describes EPA’s

data editing procedures and statistical methodology for calculating the proposed effluent

limitations.

Except at facilities where the process wastewater introduced into a POTW does

not exceed 1 MGY, any existing indirect discharging facility in the General Metals Subcategory

must achieve the following pretreatment standards.

Table 14-14

PSES for the General Metals Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 87 50

2. Total Organics Parameter (TOP) 9.09.0 4.34.3

3. Cadmium 0.14 0.09

4. Chromium 0.25 0.14

5. Copper 0.55 0.28

6. Total Cyanide 0.21 0.13

7. Amenable Cyanide 0.14 0.07

8. Lead 0.04 0.03

9. Manganese 0.13 0.09

10. Molybdenum 0.79 0.49

11. Nickel 0.50 0.31

12. Silver 0.22 0.09

13. Sulfide, Total 31 13

14. Tin 1.4 0.67

15. Zinc 0.38 0.22

As discussed in Section 15.2.7, upon agreement with the permitting authority, 

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. A POTW has the option of imposing mass-based standards in place

of the concentration based standards. To convert to mass-based standards, multiply each

parameter’s concentration-based standard times the average daily flow of process wastewater

discharged by the source into the POTW. 
14.0 - Effluent Limitations and Standards

14-44

14.4.3 PSES for the Metal Finishing Job Shops Subcategory

As discussed in Section 14.4, one of the factors that EPA uses to determine the

need for pretreatment standards is whether the pollutants discharged by an industry pass through

a POTW. The Agency only applies the pass-through analysis to pollutants that it selected for

regulation under BAT. For the Metal Finishing Job Shops Subcategory, EPA determined that 12

pollutants pass through; therefore, EPA is proposing pretreatment standards equivalent to BAT

for these pollutants. In addition, EPA is proposing a standard for total sulfide based on potential

POTW interference or upset associated with discharges of total sulfide from MP&M facilities. 

EPA is also proposing standards for TOC and TOP as part of a compliance alternative for

organic pollutant discharges. (See Section 7 for a more detailed discussion of the pass-through

analysis).

As discussed in Section 14.4.1, in the Agency's engineering assessment of the best

available technology for pretreatment of wastewater from the Metal Finishing Job Shops

Subcategory, EPA considered the same technology options for PSES as it did for BAT with the

additional consideration of a flow cutoff. The Agency selected BAT Option 2 for PSES for many

of the same reasons it selected that option for BPT and BAT (See Section 14.1.2 and 14.3.2) and

provides additional rationale below. EPA is proposing that pretreatment standards based on

Option 2 be applied to all facilities (i.e., no flow exclusion) for the Metal Finishing Job Shops

Subcategory. 

The Agency estimates that 1,514 Metal Finishing Job Shops currently discharge

MP&M process wastewater to POTWs. The Agency projects that 128 of these facilities (10

percent of the indirect discharging facilities when baseline closures are taken into consideration)

might close as a result of the proposed option. EPA concluded that this level of impact was

economically achievable for the subcategory as a whole but, in an effort to minimize the impacts,

considered several flow exemptions and compliance alternatives. 

The Agency believes that Option 2 represents the “best available” technology as it

achieves a high level of pollutant control, treating all priority pollutants to very low levels, often

at or near the analytical minimum level. Approximately 55 percent of the indirect discharging

facilities in the Metal Finishing Job Shops Subcategory employ chemical precipitation followed

by a sedimentation (Option 2) while less than 1 percent employ microfiltration after chemical

precipitation (Option 4). 

EPA did evaluate Option 4 as a basis for establishing PSES. EPA estimates that

the economic impact due to the additional controls at Option 4 levels would result in 393 facility

closures (32 percent of the indirect discharging facilities in this subcategory). Thus, EPA

rejected Option 4 as not economically achievable. 

The Agency evaluated Option 2 with several levels of flow cutoffs, compliance

options, and various combinations of the two. EPA analyzed the cutoffs and alternative

compliance options in terms of reduction in economic impacts and quantity of toxic pound-
14.0 - Effluent Limitations and Standards

14-45

equivalents discharged to the environment. EPA did not consider the reduction in POTW burden

for this subcategory, unlike the General Metals Subcategory, because EPA has already

established PSES for all of the facilities in this subcategory under 40 CFR 413 and 40 CFR 433,

and local control authorities would not have to develop entirely new permits (or other control

mechanisms) for these facilities. 

EPA did consider alternatives. First, EPA analyzed a 1 MGY flow cutoff, which

would exclude 831 of the 1,514 estimated Metal Finishing Job Shops facilities (or 457 of the

1,231 facilities after baseline closures are removed from the analysis), and would reduce the

economic impacts for 23 of the 128 facilities EPA projected would close under Option 2. This

represents less than 2 percent of the 1,231 metal finishing jobs that operate in the baseline and 18

percent of the projected facility closures under Option 2. This means that there are still 105 of

the 128 facilities that EPA predicts to close with a 1 MGY flow cutoff. Further, EPA

determined that the proposed regulation would control an average of 135 pound-equivalents per

year from facilities discharging less than 1 MGY. This is higher than the level at which EPA has

previously determined that discharges are not significant enough to warrant national regulation. 

Facilities discharging less than 1 MGY are associated with removals under the proposed option

of about 61,000 pound-equivalents (or about 3 percent of the removals associated with the

proposed option) at an incremental cost-effectiveness of about $300 per pound-equivalent (1981

dollars). This is higher than has generally been associated with pretreatment standards in the

past, though not necessarily higher than has been associated with the smaller facilities regulated

with pretreatment standards in the past. This is to be expected since smaller facilities incur the

same level of costs for monitoring as larger facilities and are sometimes forced to purchase larger

capacity treatment units than they would need due to availability. Nonetheless, the Agency

concluded that the pollutant reductions associated with Option 2 were feasible and achievable

and the economic impacts were not substantially mitigated under the 1 MGY flow cutoff, so a 1

MGY flow cutoff is not being proposed for the Metal Finishing Job Shops Subcategory. 

Second, EPA considered an option with (a) MP&M pretreatment standards for

facilities discharging greater than 1 MGY and (b) a pollution prevention alternative for those

discharging less than 1 MGY. Under this option, EPA would exclude from the MP&M numeric

pretreatment standards based on Option 2 those metal finishing job shops discharging less than 1

MGY that choose to perform the pollution prevention and water conservation activities discussed

in the Appendix to this section (referred to as the “P2 alternative”). EPA would require the low

flow facilities to continue to meet the pretreatment standards codified at 40 CFR Part 433, which

remain unchanged by this proposed rule. All facilities discharging greater than 1 MGY (and

those facilities discharging less than 1 MGY but not choosing the P2 alternative) would be

subject to the MP&M pretreatment standards for this subcategory. In analyzing this option, EPA

assumed that all facilities discharging less than 1 MGY chose the P2 alternative. EPA’s analysis

shows that this option would reduce the facility closures for 23 of the 128 facilities EPA

projected would close under Option 2 (no flow cutoff). As with the 1 MGY flow cutoff approach

discussed above, this represents less than 2 percent of the 1,231 metal finishing job shops that

operate in the baseline and about 18 percent of the closures projected by the proposed option. 

Further, although the P2 alternative would be somewhat effective in reducing toxic discharges,
14.0 - Effluent Limitations and Standards

14-46

the option is not as protective as the numeric pretreatment standards based on Option 2. For

facilities discharging less than 1 MGY, EPA estimates that the P2 alternative would control 59

pound-equivalents per facility per year (compared to 135 pound-equivalents per facility at Option

2). Thus, EPA is not proposing the option of a 1 MGY flow cutoff combined with a P2

alternative for the proposed rule.

Third, EPA analyzed a 2 MGY flow cutoff, which would exclude 1,024 facilities

(66 percent) from MP&M pretreatment standards. Excluding a larger number of facilities

(compared to the 1 MGY cutoff option) resulted in a smaller number of facility closures. For this

option, EPA predicts that 59 facilities (approximately 5 percent of the indirect discharging

facilities) might close. EPA estimates that the facilities discharging less than 2 MGY represent

less than 12 percent of the total pound-equivalents currently discharged by facilities in this

subcategory. For facilities discharging less than 2 MGY, EPA estimates that pretreatment

standards would remove an average of 189 pound-equivalents per facility per year. While a 2

MGY flow cutoff reduces the number of facility closures, EPA concluded that the pollutant

reductions associated with Option 2 were feasible and achievable and is not proposing a 2 MGY

flow cutoff.

Fourth, EPA analyzed the 2 MGY flow cutoff with the P2 alternative for those

facilities below the cutoff. Under this option, EPA would exclude from the MP&M numeric

pretreatment standards based on Option 2 those metal finishing job shops discharging less than 2

MGY that choose to perform the P2 alternative. EPA would require the low-flow facilities to

continue to meet the pretreatment standards codified at 40 CFR Part 433, which remain

unchanged by this proposed rule. All facilities discharging greater than 2 MGY (and those

facilities discharging less than 2 MGY but not choosing the P2 alternative) would be subject to

the MP&M pretreatment standards for this subcategory. In analyzing this option, EPA assumed

that all facilities discharging less than 2 MGY chose the P2 alternative. EPA’s analysis shows

that this option may not reduce the number of facility closures any further than a 1 MGY flow

cutoff (or 1 MGY P2 alternative). The model facilities representing the facilities that close with

flows of 2 MGY or less would require annualized costs to be reduced at least 68 percent in order

to avoid closure. Since there are some compliance costs associated with implementing the

practices of the P2 alternative, EPA estimates that these may close under the P2 alternative. 

Although the P2 alternative reduces the number of facility closures as compared to an option

with no flow cutoff, the option is not as protective as numeric pretreatment standards based on

Option 2. For facilities discharging less than 2 MGY, EPA estimates that the P2 alternative

would control an average of 67 pound-equivalents per facility per year (compared to 189 poundequivalents per facility at Option 2). Thus, EPA is not proposing the option of 2 MGY flow

cutoff combined with a P2 alternative.

In summary, for all of the flow cutoff and P2 alternatives that EPA considered for

this subcategory, the Agency identified no combination that would significantly reduce the

economic impacts without also significantly reducing control of pollutants. At all the flow

cutoffs and compliance alternatives, EPA concluded that the potential removals the Agency

would be choosing to forego were above levels which EPA has previously determined
14.0 - Effluent Limitations and Standards

14-47

insufficient to warrant national categorical pretreatment standards. Thus, EPA is not proposing a

flow cutoff for this subcategory. Under the proposed option all facilities in this subcategory

would be subject to the pretreatment standards, which would reduce pass-through of pollutants

based on a technology EPA has determined to be technologically feasible and economically

achievable. 

The Appendix to this section discusses the P2 alternative. Table 14-12 shows the

pounds of pollutants removed by the proposed option; Table 14-13 summarizes the costs and

economic impacts associated with the proposed option. Table 14-15 lists PSES for the Metal

Finishing Job Shops Subcategory. Section 10.0 describes EPA’s data editing procedures and

statistical methodology for calculating the proposed effluent limits.

Existing indirect discharging facilities in the Metal Finishing Job Shops

Subcategory must achieve the following pretreatment standards.

Table 14-15

PSES for the Metal Finishing Job Shops Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 78 59

2. Total Organics Parameter (TOP) 9.0 4.3

3. Cadmium 0.21 0.09

4. Chromium 1.3 0.55

5. Copper 1.3 0.57

6. Total Cyanide 0.21 0.13

7. Amenable Cyanide 0.14 0.07

8. Lead 0.12 0.09

9. Manganese 0.25 0.10

10. Molybdenum 0.79 0.49

11. Nickel 1.5 0.64

12. Silver 0.15 0.06

13. Sulfide, Total 31 13

14. Tin 1.8 1.4

15. Zinc 0.35 0.17
14.0 - Effluent Limitations and Standards

14-48

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7. A POTW has the option of imposing mass-based standards in place

of the concentration-based standards. To convert to mass-based standards, multiply each

parameter’s concentration-based standard by the average daily flow of process wastewater

discharged by the source into the POTW.

14.4.4 PSES for the Non-Chromium Anodizing Subcategory

EPA is proposing to not establish PSES for the Non-Chromium Anodizing

Subcategory based on the economic impacts associated with Option 2 and the small quantity of

toxic pollutants discharged by facilities in this subcategory remaining covered at an economically

achievable flow cutoff. EPA determined that 60 percent of the indirect discharging facilities in

this subcategory would close as a result of complying with Option 2 based standards. 

Pretreatment standards for this subcategory based on either Option 2 or Option 4 would require

facilities to remove large quantities of aluminum, a metal that is beneficial to POTWs because it

assists in the flocculation of wastewater prior to sedimentation. Aluminum anodizers use a large

quantity of water in their anodizing processes and produce a wastewater that contains mostly

aluminum. If the Agency proposed pretreatment standards for this subcategory, even without

regulating aluminum, the standards would require facilities to install very large treatment systems

(because of their high flow volume) and would remove large quantities of aluminum in order to

remove small quantities of other metals such as nickel, zinc, and manganese. Therefore, EPA

determined that the benefits of the aluminum discharge to POTWs outweighed the benefits

gained from the removal of small quantities of other metals. In addition, because EPA has

already promulgated pretreatment standards for non-chromium anodizers at 40 CFR 413 and 433,

there is already a level of control for the small quantities of other metals being discharged along

with the aluminum. Facilities subject to this subcategory must still comply with applicable PSES

limitations (either 40 CFR 413 or 40 CFR 433). (See 40 CFR 438.40(b).)

14.4.5 PSES for the Printed Wiring Board Subcategory

As discussed above in Section 14.4.1, one of the factors that EPA uses to

determine the need for pretreatment standards is whether the pollutants discharged by an industry

pass through a POTW. The Agency only applies the pass-through analysis to pollutants that it

selected for regulation under BAT. For the Printed Wiring Board Subcategory, EPA determined

that nine pollutants pass through; therefore, EPA is proposing pretreatment standards equivalent

to BAT for these pollutants. In addition, EPA is proposing a standard for total sulfide based on

potential POTW interference or upset associated with discharges of total sulfide from MP&M

facilities. EPA is also proposing standards for TOC and TOP as part of a compliance alternative

for organic pollutant discharges. (See Section 7 for a more detailed discussion of the passthrough analysis).
14.0 - Effluent Limitations and Standards

14-49

As discussed in Section 14.4.1, in the Agency's engineering assessment of the best

available technology for pretreatment of wastewater from the Printed Wiring Board Subcategory,

EPA considered the same technology options for PSES as it did for BAT with the additional

consideration of a flow cutoff exclusion. The Agency selected Option 2 for PSES for many of

the same reasons it selected that option for BPT and BAT (see Sections 14.1.4 and 14.3.4) and

provides additional rationale below. EPA also determined that pretreatment standards based on

Option 2 for all facilities (i.e., no flow exclusion) are appropriate for the Printed Wiring Board

Subcategory. The Agency estimates that 621 printed wiring board facilities currently discharge

MP&M process wastewater to POTWs. The Agency projects that seven of these facilities (1

percent of the current indirect discharging population) might close as a result of the MP&M

regulation. EPA concluded that this level of impact was economically achievable for the

subcategory as a whole, but in an effort to minimize the impacts and/or maintain existing

limitations for facilities where potential removals may not be sufficient to warrant national

regulation, considered flow exemptions and compliance alternatives. 

The Agency believes that Option 2 represents the “best available” technology as it

achieves a high level of pollutant control, treating all priority pollutants to very low levels, often

at or near the analytical minimum level. Approximately 80 percent of the indirect discharging

facilities in the Printed Wiring Board Subcategory employ chemical precipitation followed by

sedimentation (Option 2), while 2 percent employ microfiltration after chemical precipitation

(Option 4). 

EPA did evaluate Option 4 as a basis for establishing PSES. EPA estimates that

the economic impact due to the additional controls at Option 4 levels would result in 18 more

facility closures than Option 2 (total of 25 closures). EPA does consider Option 4 to be

economically achievable for this subcategory. However, EPA is not proposing to establish 

PSES limitations based on Option 4 because it determined that Option 2 achieves nearly

equivalent reductions in pound-equivalents for much less cost. By selecting Option 2 as the basis

for PSES, EPA reduced annualized compliance costs by $75 million (1996 dollars) while only

losing 0.5 percent of the toxic pound-equivalents that would be removed under Option 4. The

Agency concluded that the additional costs of Option 4 do not justify the additional insignificant

amount of pollutant removals achieved for indirect dischargers in this subcategory. Therefore,

EPA determined that Option 2 is the “best available” technology economically achievable for the

Printed Wiring Board Subcategory. 

Although EPA concluded that the level of economic impact associated with

Option 2 with no flow cutoff was economically achievable, it considered flow exclusions in an

effort to minimize the impacts and/or maintain existing limitations for facilities where potential

removals may not be significant enough to warrant national regulation. EPA did not consider the

reduction in POTW burden for this subcategory, unlike the General Metals Subcategory, because

EPA has already established PSES for all of the facilities in this subcategory under 40 CFR 413

and 433, and local control authorities would not have to develop entirely new permits (or other

control mechanisms) for these facilities. EPA analyzed a 1 MGY flow cutoff, which would

exclude 85 facilities, but would not reduce economic impacts. The same seven facilities that
14.0 - Effluent Limitations and Standards

14-50

EPA predicted to close with no flow cutoff are also expected to close with a 1 MGY flow cutoff. 

EPA determined that the proposed regulation would remove a total of less than 500 poundequivalents from the facilities discharging less than 1 MGY (after removing baseline closures

from the analysis), or less than 10 pound-equivalents per facility. The incremental removals

beyond current regulations is very small for facilities less than 1 MGY, and therefore EPA will

consider the 1 MGY cutoff at final. However, the Agency concluded that the significant

pollutant reductions associated with Option 2 were feasible and achievable, the economic

impacts were not mitigated at a 1 MGY flow cutoff for this subcategory and POTW burden

would not be reduced with a flow cutoff, and thus is not proposing a 1 MGY flow cutoff for this

subcategory. Table 14-12 shows the pounds of pollutants removed by the proposed option; Table

14-13 summarizes the costs and economic impacts associated with the proposed option. Table

14-16 lists PSES for the Printed Wiring Board Subcategory. Section 10.0 describes EPA’s data

editing procedures and statistical methodology for calculating the proposed effluent limits for

this subcategory.

Existing indirect discharging facilities in the Printed Wiring Board Subcategory

must achieve the following pretreatment standards.

Table 14-16

PSES for the Printed Wiring Board Subcategory

Regulated Parameter

Maximum

Daily

 (mg/L (ppm))

Maximum

Monthly Avg.

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 101 67

2. Total Organics Parameter (TOP) 9.0 4.3

3. Chromium 0.25 0.14

4. Copper 0.55 0.28

5. Total Cyanide 0.21 0.13

6. Amenable Cyanide 0.14 0.07

7. Lead 0.04 0.03

8. Manganese 1.3 0.64

9. Nickel 0.30 0.14

10. Sulfide, Total 31 13

11. Tin 0.31 0.14

12. Zinc 0.38 0.22

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or
14.0 - Effluent Limitations and Standards

14-51

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7. A POTW has the option of imposing mass-based standards in place of the

concentration-based standards. To convert to mass-based standards, multiply each parameter’s

concentration-based standard by the average daily flow of process wastewater discharged by the

source into the POTW.

14.4.6 PSES for the Steel Forming and Finishing Subcategory

As discussed above in Section 14.4, one of the factors that EPA uses to determine

the need for pretreatment standards is whether the pollutants discharged by an industry pass

through a POTW The Agency only applies the pass-through analysis to pollutants that it selected

for regulation under BAT. For the Steel Forming and Finishing Subcategory, EPA determined

that 13 pollutants pass through; therefore, EPA is proposing pretreatment standards equivalent to

BAT for these pollutants. In addition, EPA is proposing a standard for total sulfide based on

potential POTW interference or upset associated with discharges of total sulfide from MP&M

facilities. EPA is also proposing standards for TOC and TOP as part of a compliance alternative

for organic pollutant discharges. (See Section 7 for a more detailed discussion of the passthrough analysis).

As discussed in Section 14.4.1 above, in the Agency's engineering assessment of

the best available technology for pretreatment of wastewater from the Steel Forming and

Finishing Subcategory, EPA considered the same technology options for PSES as it did for BAT

with the additional consideration of a flow cutoff exclusion. The Agency selected Option 2 for

PSES for many of the same reasons it selected that option for BPT and BAT (see Sections 14.1.5

and 14.3.5) and provides additional rationale below. EPA is proposing pretreatment standards

based on Option 2 for all facilities (i.e., no flow exclusion) for the Steel Forming and Finishing

Subcategory. 

The Agency estimates that 110 Steel Forming and Finishing facilities currently

discharge MP&M process wastewater to POTWs. The Agency projects that six of these facilities

(6 percent of the current indirect discharging population) might close as a result of the MP&M

regulation. EPA concluded that this level of impact was economically achievable for the

subcategory as a whole, but in an effort to minimize the impacts, considered flow exemptions

and compliance alternatives. 

The Agency believes that Option 2 represents the “best available” technology as it

achieves a high level of pollutant control, treating all priority pollutants to very low levels, often

at or near the analytical minimum level. Approximately 63 percent of the indirect discharging

facilities in the Steel Forming and Finishing Subcategory employ chemical precipitation followed

by sedimentation (Option 2), while no facilities employ microfiltration after chemical

precipitation (Option 4). 
14.0 - Effluent Limitations and Standards

14-52

EPA did evaluate Option 4 as a basis for establishing PSES. EPA estimates that

the economic impact due to the additional controls at Option 4 levels would result in the same

number of facility closures (six) as Option 2. Therefore, EPA does consider Option 4 to be

economically achievable for this subcategory. However, EPA is not proposing to establish PSES

limitations based on Option 4 because it determined that Option 2 achieves nearly equivalent

reductions in pound-equivalents for much less cost. By selecting Option 2 as the basis for PSES,

EPA reduced annualized compliance costs by $12 million (1996 dollars) while only losing 0.6

percent of the toxic pound-equivalents that would be removed under Option 4. The Agency

concluded that the additional costs of Option 4 do not justify the additional insignificant

pollutant removals achieved for indirect discharging facilities in this subcategory. Therefore,

EPA determined that Option 2 is the “best available” technology economically achievable for the

Steel Forming and Finishing Subcategory. 

Although EPA concluded that the level of economic impact associated with

Option 2 with no flow cutoff was economically achievable, it considered flow exclusions in an

effort to minimize the impacts. EPA did not consider the reduction in POTW burden for this

subcategory, unlike the General Metals subcategory, because EPA has already established PSES

for all of the facilities in this subcategory under 40 CFR 420, and local control authorities would

not have to develop entirely new permits (or other control mechanisms) for these facilities. 

However, to mitigate economic impacts (and or maintain existing limitations for facilities where

potential removals may not be sufficient to warrant national regulation), EPA analyzed a 1 MGY

flow cutoff, which would exclude 21 facilities (after accounting for baseline closures), and a 2

MGY flow cutoff which would exclude 30 facilities. Neither a 1 MGY flow cutoff nor a 2 MGY

flow cutoff would reduce economic impacts. The same 6 facilities that EPA predicted to close

with no flow cutoff are also expected to close with either a 1 or 2 MGY flow cutoff. However, a

1 MGY flow cutoff would eliminate less than 100 total pound-equivalents that would be

removed under the proposed option, or less than 5 pound-pound-equivalents per excluded

facility, while a 2 MGY flow cutoff would eliminate less than 200 pound-equivalents total, or

less than 7 pound-equivalents per excluded facility. These incremental removals beyond current

regulations are very small, and therefore EPA will consider the 1 and 2 MGY cutoffs at final. 

Although a 3 MGY flow cutoff would reduce projected economic impacts by half (3 projected

closures instead of 6), it would eliminate 2,157 pound-equivalent removals, or about 58 poundequivalents per facility. These incremental removals are nearly twice the removals (on a per

facility basis) than would have been realized by regulating Industrial Laundry and Landfill

facilities. Because EPA has concluded that the proposed option is feasible and achievable, and

POTW burden would not be reduced with a flow cutoff, EPA is not proposing a flow cutoff for

the Steel Forming and Finishing Subcategory. 

EPA expresses the proposed effluent limitations guidelines and standards for

BPT, BAT, NSPS, PSES, and PSNS for the Steel Forming and Finishing Subcategory as mass

limitations in pounds/1,000 pounds of product. Permit writers and control authorities shall

compute mass effluent limitations and pretreatment requirements for each forming/finishing

operation by multiplying the average daily production rate (or other reasonable measure of

production) by the respective effluent limitations guidelines or standards listed in Table 14-17. 
14.0 - Effluent Limitations and Standards

14-53

Production-normalized flows for the Steel Forming and Finishing Subcategory are listed in Table

14-7. Permit writers and control authorities shall not include production from unit operations

that do not generate or discharge process wastewater in the calculation of the operating rate. 

These mass-based limitations apply to the operations listed and defined in Section 14.1.5

Existing indirect discharging facilities in the Steel Forming and Finishing

Subcategory must achieve the following pretreatment standards.

Table 14-17

PSES for the Steel Forming and Finishing Subcategory

Pollutant TSS O&G (as HEM)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0709 0.0369 0.0312 0.0239

(b) Alkaline Cleaning 0.0709 0.0369 0.0312 0.0239

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00355 0.00184 0.00156 0.00120

(e) Electroplating 0.142 0.0737 0.0623 0.0478

(f) Hot Dip Coating 0.0206 0.0107 0.00903 0.00693

(g) Lubrication 0.00170 0.000884 0.000748 0.000574

(h) Mechanical

Descaling

0.000284 0.000148 0.000125 0.0000956

(i) Painting 0.00922 0.00479 0.00405 0.00311

(j) Pressure

Deformation 

0.00355 0.00184 0.00156 0.00120

Pollutant TOC TOP

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.181 0.103 0.0188 0.00896

(b) Alkaline Cleaning 0.181 0.103 0.0188 0.00896

(c) Cold Forming 0 0 0 0
Table 14-17 (Continued)

14.0 - Effluent Limitations and Standards

Pollutant TOC TOP

14-54

(d) Continuous

Annealing

0.00901 0.00514 0.000937 0.000448

(e) Electroplating 0.361 0.206 0.0375 0.0180

(f) Hot Dip Coating 0.0523 0.0300 0.00543 0.00260

(g) Lubrication 0.00433 0.00247 0.000450 0.000215

(h) Mechanical

Descaling

0.000721 0.000411 0.0000750 0.0000359

(i) Painting 0.0235 0.0134 0.00244 0.00117

(j) Pressure

Deformation 

0.00901 0.00514 0.000937 0.000448

Pollutant Cadmium Chromium

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000292 0.000188 0.000509 0.000277

(b) Alkaline Cleaning 0.000292 0.000188 0.000509 0.000277

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000146 0.00000938 0.0000255 0.0000139

(e) Electroplating 0.000583 0.000376 0.00102 0.000553

(f) Hot Dip Coating 0.0000845 0.0000545 0.000148 0.0000801

(g) Lubrication 0.00000699 0.00000450 0.0000123 0.00000663

(h) Mechanical

Descaling

0.00000116 0.00000075 0.00000204 0.00000110

(i) Painting 0.0000379 0.0000244 0.0000662 0.0000359

(j) Pressure

Deformation 

0.0000146 0.00000938 0.0000255 0.0000139
Table 14-17 (Continued)

14.0 - Effluent Limitations and Standards

14-55

Pollutant Copper Lead

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00114 0.000565 0.0000737 0.0000522

(b) Alkaline Cleaning 0.00114 0.000565 0.0000737 0.0000522

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000570 0.0000283 0.00000368 0.00000261

(e) Electroplating 0.00228 0.00113 0.000148 0.000105

(f) Hot Dip Coating 0.000331 0.000164 0.0000214 0.0000152

(g) Lubrication 0.0000274 0.0000136 0.00000177 0.00000125

(h) Mechanical

Descaling

0.00000455 0.00000226 0.00000029 0.00000021

(i) Painting 0.000148 0.0000734 0.00000957 0.00000678

(j) Pressure

Deformation 

0.0000570 0.0000283 0.00000368 0.00000261

Pollutant Manganese Molybdenum

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000269 0.000183 0.00164 0.00103

(b) Alkaline Cleaning 0.000269 0.000183 0.00164 0.00103

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000135 0.00000914 0.0000820 0.0000511

(e) Electroplating 0.000537 0.000366 0.00328 0.00205

(f) Hot Dip Coating 0.0000779 0.0000531 0.000476 0.000297

(g) Lubrication 0.00000644 0.00000439 0.0000394 0.0000246

(h) Mechanical

Descaling

0.00000107 0.00000073 0.00000656 0.00000409

(i) Painting 0.0000350 0.0000238 0.000214 0.000133
Table 14-17 (Continued)

14.0 - Effluent Limitations and Standards

Pollutant Manganese Molybdenum

14-56

(j) Pressure

Deformation 

0.0000135 0.00000914 0.0000820 0.0000511

Pollutant Nickel Silver

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00104 0.000642 0.000456 0.000187

(b) Alkaline Cleaning 0.00104 0.000642 0.000456 0.000187

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000520 0.0000321 0.0000228 0.00000934

(e) Electroplating 0.00208 0.00129 0.000912 0.000374

(f) Hot Dip Coating 0.000302 0.000186 0.000133 0.0000542

(g) Lubrication 0.0000250 0.0000154 0.0000110 0.00000448

(h) Mechanical

Descaling

0.00000415 0.00000257 0.00000182 0.00000075

(i) Painting 0.000135 0.0000834 0.0000593 0.0000243

(j) Pressure

Deformation 

0.0000520 0.0000321 0.0000228 0.00000934

Pollutant Sulfide (as S) Tin

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0630 0.0267 0.00274 0.00139

(b) Alkaline Cleaning 0.0630 0.0267 0.00274 0.00139

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00315 0.00134 0.000137 0.0000694

(e) Electroplating 0.126 0.0534 0.00547 0.00278

(f) Hot Dip Coating 0.0183 0.00774 0.000793 0.000403
Table 14-17 (Continued)

14.0 - Effluent Limitations and Standards

14-57

(g) Lubrication 0.00151 0.000641 0.0000656 0.0000333

(h) Mechanical

Descaling

0.000252 0.000107 0.0000110 0.00000555

(i) Painting 0.00818 0.00347 0.000356 0.000181

(j) Pressure

Deformation 

0.00315 0.00134 0.000137 0.0000694

Pollutant Zinc

Forming/Finishing Operation

Maximum Daily

(lbs/1000 lbs of product)

Maximum Monthly Avg.

(lbs/1000 lbs of product)

(a) Acid Pickling 0.000793 0.000456

(b) Alkaline Cleaning 0.000793 0.000456

(c) Cold Forming 0 0

(d) Continuous Annealing 0.0000397 0.0000228

(e) Electroplating 0.00159 0.000912

(f) Hot Dip Coating 0.000230 0.000133

(g) Lubrication 0.0000191 0.0000110

(h) Mechanical Descaling 0.00000317 0.00000182

(i) Painting 0.000103 0.0000593

(j) Pressure Deformation 0.0000397 0.0000228

Pollutant Cyanide (T) Cyanide (A)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Electroplating 0.000865 0.000513 0.000580 0.000282

As discussed Section 15.2.7, upon agreement with the permitting authority, facilities with

cyanide treatment have the option of achieving the limitation for either amenable or total cyanide. 

Upon agreement with the permitting authority, facilities must choose to monitor for TOP or

TOC, or implement a management plan for organic chemicals as specified in Section 15.2.7.
14.0 - Effluent Limitations and Standards

14-58

14.4.7 PSES for the Oily Wastes Subcategory

As discussed in Section 14.4, two of the factors that EPA uses to determine the

need for pretreatment standards is whether the pollutants discharged by an industry pass through

or interfere with a POTW. For the Oily Wastes Subcategory, EPA is proposing pretreatment

standards equivalent to BAT for the following three pollutants or pollutant parameters: TOC,

TOP and total sulfide. In addition, EPA is proposing a standard for total sulfide based on

potential POTW interference or upset associated with discharges of total sulfide from MP&M

facilities. EPA is also proposing standards for TOC and TOP as part of a compliance alternative

for organic pollutant discharges. (See Section 7 for a more detailed discussion of the passthrough analysis).

As discussed in Section 14.4.1, in the Agency's engineering assessment of the best

available technology for pretreatment of wastewater from the Oily Wastes Subcategory, EPA

considered the same technology options for PSES as it did for BAT with the additional

consideration of a flow cutoff exclusion. The Agency selected BAT Option 6 with a 2 MGY

flow cutoff for PSES. The Agency selected Option 6 for PSES for many of the same reasons it

selected that option for BPT and BAT (See Sections 14.1.6 and 14.3.6) and provides additional

rationale below. EPA is proposing the 2 MGY flow cutoff primarily to reduce the burden on

POTWs. In the proposal EPA solicits comments on a 3 MGY cutoff as a possible alternative to

further reduce impacts.

EPA determined that Option 6 represented the best available technology and that

Option 6 with a 2 MGY flow cutoff was economically achievable and greatly reduced the burden

on POTWs. This option results in 14 facility closures (less than 1 percent of the indirect

discharging Oily Wastes Subcategory population). Additionally, the Agency believes that Option

6 represents the “best available” technology as it achieves a high level of pollutant control,

treating all priority pollutants to very low levels, often at or near the analytical minimum level. 

According to EPA’s detailed questionnaires, approximately 44 percent of the indirect discharging

facilities in the Oily Wastes Subcategory employ oil/water separation by chemical emulsion

breaking followed by gravity separation and oil skimming (Option 6), while no facilities employ

ultrafiltration (Option 8). 

EPA did evaluate BPT Option 8 with a 2 MGY flow cutoff as a basis for

establishing PSES more stringent than the BAT level of control being proposed today. EPA

estimates that the economic impact due to the additional controls at Option 8 levels would result

in the same number of facility closures (14) as Option 6. Therefore, EPA does consider Option 8

to be economically achievable for this subcategory. However, based on the available data base,

EPA is not proposing to establish PSES limitations based on Option 8 because it removes fewer

pound-equivalents than Option 6. Therefore, the Agency determined that Option 6 is the “best

available” technology economically achievable for the removal of priority pollutants from

wastewater generated at Oily Wastes Subcategory facilities. 
14.0 - Effluent Limitations and Standards

14-59

Considering the large number of indirect dischargers that have the potential to be

covered by this proposed regulation, an important issue to the affected industry and to permit

writers is the potentially enormous administrative burden associated with issuing permits or other

control mechanisms for all of these facilities. Therefore, in developing this proposal, EPA

looked for means of reducing the administrative burden, monitoring requirements, and reporting

requirements. To meet this end, the Agency is proposing a 2 MGY flow cutoff for the Oily

Wastes Subcategory. Under this proposed option, facilities in the Oily Wastes Subcategory that

discharge greater than 2 MGY per year of MP&M process wastewater would be subject to the

proposed pretreatment standards. However, those facilities in the Oily Wastes Subcategory that

discharge 2 MGY or less would not be subject to MP&M PSES requirements. These facilities

would, however, remain subject to the existing general pretreatment standards at 40 CFR Part

403.

The Agency is proposing the 2 MGY flow cutoff exclusion for the Oily Wastes

Subcategory based on several factors. First, and the most important factor, is the overall size of

the subcategory. EPA estimates that there are approximately 28,500 indirect discharging

facilities in the Oily Wastes Subcategory, of which over 99 percent are not currently regulated by

categorical pretreatment standards. Establishing an MP&M pretreatment standard for all 28,500

facilities would nearly double the number of permits that local authorities are currently

responsible for. EPA concluded that this increased permit burden was not reasonable given the

projected loadings reductions and therefore explored potential flow cutoffs as a way to reduce the

impact on POTW permitting authorities. 

Second, EPA is proposing the 2 MGY flow cutoff for this subcategory based in

part on the small number of pound-equivalents that would be removed by facilities with annual

wastewater flows less than or equal to 2 MGY. EPA determined that after removing facilities

that close in the baseline (“baseline closures”) from the analysis, over 99 percent of the indirect

discharging facilities in the Oily Wastes Subcategory discharge less than or equal to 2 MGY. 

EPA estimates average removals of only 2 pound-equivalents per facility per year for these

facilities. 

In addition, EPA determined that for those facilities in this subcategory that

discharge between 1 and 2 MGY the MP&M regulation would remove an average of 31 poundequivalents per year per facility. These reductions, as discussed previously, are lower than those

projected for industrial laundries and landfills, for which EPA determined national regulation

was not warranted. The Agency concluded that regulation of facilities discharging only 2 poundequivalents per year (with those discharging between 1 and 2 MGY at 31 pound-equivalents per

year) was not justified by the additional permitting burden associated with these facilities. EPA

believes this approach would allow Control Authorities to focus their efforts on the facilities

discharging the vast majority of the pollutants, rather than dissipating their limited resources on

sites contributing much less to the overall problem. EPA does note, however, that the indirect

discharging facilities that discharge less than or equal to 2 MGY are responsible for an estimated 

78 percent of the total pound-equivalents currently discharged (approximately 51,000 of the

65,000 pound-equivalents discharged after removing baseline closures from the analysis).
14.0 - Effluent Limitations and Standards

14-60

EPA also closely evaluated Option 6 with a 3 MGY flow cutoff for the Oily

Waste Subcategory. Based on EPA’s data collection efforts, after removing facilities that close

in the baseline (“baseline closures”) from the analysis, over 99 percent of the indirect discharging

facilities in the Oily Wastes Subcategory discharge less than or equal to 3 MGY. The Agency

determined that after removing baseline closures from the analysis there are approximately 64

indirect discharge facilities in this subcategory between 2 and 3 MGY and that they discharge an

average of 24 pound-equivalents per year per facility. If EPA proposed Option 2 with a 3 MGY

flow cutoff, the economic impacts would decrease slightly (12 facility closures rather than 14 at

the proposed option). The Agency concluded that the 3 MGY flow cutoff was not necessary to

reduce POTW burden for the Oily Wastes Subcategory although it would reduce the economic

impact somewhat. EPA notes that these approximately 28,160 facilities are responsible for an

estimated 81 percent of the total pound-equivalents currently discharged (approximately 52,500

of the 65,000 pound-equivalents discharged after removing baseline closures from the analysis). 

Therefore, EPA is proposing the 2 MGY flow cutoff but is also seriously

considering a 3 MGY cutoff. EPA believes this approach would allow control authorities to

focus their efforts on the facilities discharging the vast majority of the pollutants, rather than

dissipating their limited resources on sites contributing much less to the overall problem. Table

14-12 shows the pounds of pollutants removed by the proposed option; Table 14-13 summarizes

the costs and economic impacts associated with the proposed option. (Both tables include

facilities that close in the baseline). EPA’s methodology for identifying baseline closures is

discussed in the EEBA. 

Except at facilities where the process wastewater introduced into a POTW does

not exceed 2 MGY, existing indirect discharging facilities in the Oily Wastes Subcategory must

achieve the following pretreatment standards.

Table 14-18

PSES for the Oily Wastes Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 633 378

2. Total Organics Parameter (TOP) 9.0 4.3

3. Sulfide, Total 31 13

Upon agreement with the permitting authority, facilities must choose to monitor

for TOP or TOC, or implement a management plan for organic chemicals as specified in Section

15.2.7. A POTW has the option of imposing mass-based standards in place of the concentration-
14.0 - Effluent Limitations and Standards

14-61

based standards. To convert to mass-based standards, multiply each parameter’s concentrationbased standard by the average daily flow of process wastewater discharged by the source into the

POTW. 

14.4.8 PSES for the Railroad Line Maintenance Subcategory

EPA is proposing not to establish PSES for the Railroad Line Maintenance

Subcategory based on the small quantity of toxic pollutants discharged by facilities in this

subcategory. The Agency estimates that there are 799 indirect discharging railroad line

maintenance facilities that currently discharge 1,800 pound-equivalents per year to the nation’s

waters (taking into account removals at the POTW), or just over 2 pound-equivalents per facility

per year. Based on this analysis, EPA preliminarily concluded that there is no need to develop

nationally applicable regulations for this subcategory due to the low levels of pollutants

discharged by facilities in this subcategory.

14.4.9 PSES for the Shipbuilding Dry Dock Subcategory

EPA is proposing not to establish PSES for the Shipbuilding Dry Dock

Subcategory based on the small number of facilities in this subcategory and on the small quantity

of toxic pollutants removed by the technology options evaluated by EPA for this proposal. The

Agency estimates that there are six indirect discharging facilities that have one or more dry docks

that currently discharge 852 pound-equivalents per year to the nation’s waters (taking into

account removals at the POTW). On a national basis, Option 8 (ultrafiltration + P2) removed

less than 1 pound-equivalent per year, while Option 10 (DAF plus P2) removed only 26 poundequivalents per year (or less than 5 pound-equivalents removed per facility per year). The

Agency estimates that all of these facilities currently have DAF treatment in place. EPA

determined that nationally applicable regulations are unnecessary at this time because of the

small number of facilities in this subcategory and based on the small amount of toxic pounds

removed by the technology options evaluated by the Agency. EPA believes that pretreatment

local limits implemented on a case-by-case basis can more appropriately address any individual

toxic parameters present at these six facilities. 

14.5 New Source Performance Standards (NSPS)

New facilities have the opportunity to incorporate the best available demonstrated

technologies including process changes, in-plant controls, and end-of-pipe treatment

technologies. The same technologies discussed previously for BAT and PSES are available as

the basis for NSPS. Since new sites have the potential to install pollution prevention and

pollution control technologies more cost effectively then existing sources, EPA strongly

considered the more advanced treatment options for NSPS. The Agency discusses its analysis of

these more stringent options for NSPS on a subcategory-by-subcategory basis below. 
14.0 - Effluent Limitations and Standards

14-62

14.5.1 NSPS for the General Metals Subcategory

EPA expects that new facilities in the General Metals Subcategory will discharge

similar quantities of the same pollutants that existing sources discharge. Therefore, the need for

NSPS regulation is the same as the need for BPT regulation. (See Section 14.1.1.)

EPA proposes NSPS for this subcategory based on BAT Option 4. The Agency

determined that Option 4 is the best available demonstrated technology for the removal of

pollutants in this subcategory. EPA’s analytical data shows that Option 4 is capable of achieving

much lower long-term averages than Option 2 for several of the metal pollutants of concern. In

addition, EPA’s data shows that microfiltration greatly reduces the variability in the

concentration of the metal pollutants in the treatment effluent. Although Option 4 costs $54,500

(1996 dollars) more than Option 2 annually for a new facility with a wastewater flow of 1.1

MGY (the wastewater flow for a representative direct discharging facility in the General Metals

Subcategory), EPA is proposing Option 4 because of the lower levels of metal pollutants in the

wastewater effluent. EPA noted in the discussion of its consideration of this technology for

BPT/BAT that it is not being proposed for BPT because the additional removals, while large

when considered across the entire population of existing facilities, were not significant on a per

facility basis, and because of concerns with potential increased loadings (relative to Option 2) of

COD and organic pollutants. 

The Agency also strongly considered proposing NSPS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. Section 10.0 describes EPA’s data editing procedures and statistical methodology for

calculating the proposed NSPS limitations for this subcategory.

The Agency also performed an economic analysis to determine if Option 4

presented a barrier to entry for new facilities in the General Metals Subcategory. EPA

determined that the cost of compliance with NSPS based on Option 4 would make up only 0.04

percent of a new facility’s projected revenues. Therefore, EPA concluded that NSPS based on

Option 4 would not create a barrier to entry. 

New direct discharging facilities in the General Metals Subcategory must achieve

must following performance standards. Discharges must remain within the pH range 6 to 9 and

must not exceed the following.
14.0 - Effluent Limitations and Standards

14-63

Table 14-19

NSPS for the General Metals Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 28 18

2. Oil and Grease (as HEM) 15 12

3. Total Organic Carbon (TOC) (as indicator) 87 50

4. Total Organics Parameter (TOP) 9.0 4.3

5. Cadmium 0.02 0.01

6. Chromium 0.17 0.07

7. Copper 0.44 0.16

8. Total Cyanide 0.21 0.13

9. Amenable Cyanide 0.14 0.07

10. Lead 0.04 0.03

11. Manganese 0.29 0.18

12. Molybdenum 0.79 0.49

13. Nickel 1.9 0.75

14. Silver 0.05 0.03

15. Sulfide, Total 31 13

16. Tin 0.03 0.03

17. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7.

14.5.2 NSPS for the Metal Finishing Job Shops Subcategory

EPA expects that new facilities in the Metal Finishing Job Shops Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore, the

need for NSPS regulation is the same as the need for BPT regulation. (See Section 14.1.2.)

EPA is proposing NSPS for this subcategory based on BAT Option 4. The

Agency determined that Option 4 is the best available demonstrated technology for the removal

of pollutants in this subcategory. EPA’s analytical data shows that Option 4 is capable of

achieving much lower long-term averages than Option 2 for several of the metal pollutants of

concern. In addition, EPA’s data shows that microfiltration greatly reduces the variability in the
14.0 - Effluent Limitations and Standards

14-64

concentration of the metal pollutants in the treatment effluent. Although Option 4 costs $72,500

(1996 dollars) more than Option 2 annually for a new facility with a wastewater flow of 6.0

MGY (the wastewater flow for a representative direct discharging facility in the Metal Finishing

Job Shops Subcategory), EPA is proposing Option 4 because of the lower levels of metal

pollutants in the treated wastewater effluent. EPA is not proposing Option 4 for BPT for this

subcategory because of the lack of significant overall pollutant removals achieved, and the fact

that it removes less COD, oil and grease, and organic pollutants.

The Agency also strongly considered proposing NSPS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. Section 10.0 describes EPA’s data editing procedures and statistical methodology for

calculating the proposed NSPS limitations. 

The Agency also performed an economic analysis in order to determine if Option

4 presented a barrier to entry for new facilities in the Metal Finishing Subcategory. EPA

determined that the cost of compliance with NSPS based on Option 4 would make up only 1.41

percent of a new facility’s projected revenues. Therefore, EPA concluded that NSPS based on

Option 4 would not create a barrier to entry. 

New direct discharging facilities in the Metal Finishing Job Shops Subcategory

must achieve the following performance standards. Discharges must remain within the pH range

6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-65

Table 14-20

NSPS for the Metal Finishing Job Shops Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 28 18

2. Oil and Grease (as HEM) 15 12

3. Total Organic Carbon (TOC) (as indicator) 78 59

4. Total Organics Parameter (TOP) 9.0 4.3

5. Cadmium 0.02 0.01

6. Chromium 0.17 0.07

7. Copper 0.44 0.16

8. Total Cyanide 0.21 0.13

9. Amenable Cyanide 0.14 0.07

10. Lead 0.04 0.03

11. Manganese 0.29 0.18

12. Molybdenum 0.79 0.49

13. Nickel 1.9 0.75

14. Silver 0.05 0.03

15. Sulfide, Total 31 13

16. Tin 0.03 0.03

17. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority, 

facilities with cyanide treatment have the option of achieving the limitation for either amenable

or total cyanide. Upon agreement with the permitting authority, facilities must choose to monitor

for TOP or TOC, or implement a management plan for organic chemicals as specified in Section

15.2.7.
14.0 - Effluent Limitations and Standards

14-66

14.5.3 NSPS for the Non-Chromium Anodizing Subcategory

EPA expects that new facilities in the Non-Chromium Anodizing Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge. EPA

notes that it did not identify any existing direct dischargers in this subcategory and that estimates

of costs and pollutant loadings were transferred from the best performing indirect dischargers in

this subcategory. Therefore, the need for NSPS regulation is the same as the need for BPT

regulation. (See Section 14.1.3.).

EPA is proposing NSPS for this subcategory based on BAT Option 2. As

discussed in the BPT analysis for this subcategory, non-chromium anodizers discharge large

quantities of aluminum but have very low levels of other metals in their wastewater. EPA

determined that Option 2 is capable of removing most of the aluminum discharged by facilities in

this subcategory and that any additional removals achieved by Option 4 are not justified by the

additional cost.

The Agency also evaluated not proposing NSPS for facilities in this subcategory

and instead continuing to require compliance with NSPS limitations established under 40 CFR

Part 433. However, the Agency has tentatively rejected this option because these new proposed

NSPS limitations require an increased removal of TSS, and the Agency feels that the pollutants

proposed for regulation here are more appropriate for the non-chromium anodizing industry. The

NSPS limitations established in 40 CFR Part 433 require facilities to meet an average monthly

discharge of 31 mg/L of TSS and allow for a maximum daily discharge of 60 mg/L. These

proposed new source MP&M limitations require non-chromium anodizers to meet an average

monthly discharge for TSS of 22 mg/L and allow for a monthly maximum discharge of 52 mg/L. 

EPA believes that the costs associated with NSPS are justified by the additional removal of TSS

from this subcategory. In addition, 40 CFR Part 433 requires non-chromium anodizers to meet

effluent limitations for seven metal pollutants. EPA’s data show that these seven metals are

present only in very small quantities at non-chromium anodizing facilities. In 40 CFR Part 433,

EPA did not establish a limit for aluminum, the metal found in the largest quantity in nonchromium anodizers’ wastewater. The Agency has determined that direct discharging facilities

in the Non-Chromium Anodizing Subcategory should have a limit for aluminum and thus is

proposing to cover them here. The Agency notes that this will reduce the number of pollutants

that non-chromium anodizers would have to monitor for.

A barrier-to-entry analysis is typically performed for new facilities by using

existing facilities as a model. However, there are no existing direct dischargers in this

subcategory. Therefore, the Agency could not perform an economic analysis to determine if

Option 2 presented a barrier to entry for new facilities in the Non-Chromium Anodizing

Subcategory. 

New direct discharging facilities in the Non-Chromium Anodizing Subcategory

must achieve the following performance standards. Discharges must remain within the pH range

of 6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-67

Table 14-21

NSPS for the Non-Chromium Anodizing Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg.

(mg/L (ppm))

1. TSS 52 22

2. O&G (as HEM) 15 12

3. Aluminum 8.2 4.0

4. Manganese 0.13 0.09

5. Nickel 0.50 0.31

6. Zinc 0.38 0.22

14.5.4 NSPS for the Printed Wiring Board Subcategory

EPA expects that new facilities in the Printed Wiring Board Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore, the

need for NSPS regulation is the same as the need for BPT regulation. (See Section 14.1.4). 

EPA is proposing NSPS for this subcategory based on BAT Option 4. The

Agency determined that Option 4 is the best available demonstrated technology for the removal

of pollutants in this subcategory. EPA’s analytical data shows that Option 4 is capable of

achieving much lower long-term averages than Option 2 for several of the metal pollutants of

concern. In addition, EPA’s data shows that microfiltration greatly reduces the variability in the

concentration of the metal pollutants in the treatment effluent. Although Option 4 costs

$162,000 more than Option 2 annually for a new facility with a wastewater flow of 25.5 MGY

(the wastewater flow for a representative direct discharging facility in the Printed Wiring Board

Subcategory), EPA is proposing Option 4 because of the lower levels of metal pollutants in the

wastewater effluent. EPA is not proposing Option 4 for BPT/BAT because of the lack of

significant overall additional removals and the fact that it removes less COD, oil and grease, and

organic pollutants, relative to Option 2. 

The Agency also strongly considered proposing NSPS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. 

The Agency also performed an economic analysis to determine if Option 4

presented a barrier to entry for new facilities in the Printed Wiring Board Subcategory. EPA

determined that the cost of compliance with NSPS based on Option 4 would make up only 0.02

percent of a new facility’s projected revenues. Therefore, EPA concluded that NSPS based on

Option 4 would not create a barrier to entry. 
14.0 - Effluent Limitations and Standards

14-68

Section 10.0 describes EPA’s data editing procedures and statistical methodology

for calculating the proposed NSPS limitations for this subcategory. Table 14-22 lists the

proposed NSPS effluent limitations for the Printed Wiring Board Subcategory. 

New direct discharging facilities in the Printed Wiring Board Subcategory must

achieve the following performance standards. Discharges must remain within the pH range 6 to

9 and must not exceed the following.

Table 14-22

NSPS for the Printed Wiring Board Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Suspended Solids (TSS) 28 18

2. Oil and Grease (as HEM) 15 12

3. Total Organic Carbon (TOC) (as indicator) 101 67

4. Total Organics Parameter (TOP) 9.09.0 4.34.3

5. Chromium 0.17 0.07

6. Copper 0.01 0.01

7. Total Cyanide 0.21 0.13

8. Amenable Cyanide 0.14 0.07

9. Lead 0.04 0.03

10. Manganese 0.29 0.18

11. Nickel 1.9 0.75

12. Sulfide, Total 31 13

13. Tin 0.09 0.07

14. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority, 

facilities with cyanide treatment have the option of achieving the limitation for either amenable

or total cyanide. Also upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.765. 

14.5.5 NSPS for the Steel Forming and Finishing Subcategory

EPA expects that new facilities in the Steel Forming and Finishing Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge. 
14.0 - Effluent Limitations and Standards

14-69

Therefore, the need for NSPS regulation is the same as the need for BPT regulation. (See

Section 14.1.5.)

EPA is proposing NSPS for this subcategory based on BAT Option 4. The

Agency determined that Option 4 is the best available demonstrated technology for the removal

of pollutants in this subcategory. EPA’s analytical data shows that Option 4 is capable of

achieving much lower long-term averages than Option 2 for several of the metal pollutants of

concern. In addition, EPA’s data shows that microfiltration greatly reduces the variability in the

concentration of the metal pollutants in the treatment effluent. Although Option 4 costs $42,400

more than Option 2 annually for a new facility with a wastewater flow of 18.4 MGY (the

wastewater flow for a representative direct discharging facilities in the Steel Forming and

Finishing Subcategory), EPA determined that the additional cost of Option 4 is justified by the

lower levels of metal pollutants in the wastewater effluent.

The Agency also strongly considered proposing NSPS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by a clarifier for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. 

The Agency also performed an economic analysis to determine if Option 4

presented a barrier to entry for new facilities in the Steel Forming and Finishing Subcategory. 

EPA determined that the cost of compliance with NSPS based on Option 4 would make up only

0.14 percent of a new facility’s projected revenues. Therefore, EPA concluded that NSPS based

on Option 4 would not create a barrier to entry. 

Section 10.0 describes EPA’s data editing procedures and statistical methodology

for calculating the proposed NSPS limitations for this subcategory. Table 14-23 lists the

proposed NSPS effluent limitations for the Steel Forming and Finishing Subcategory. 

EPA expresses the proposed effluent limitations guidelines and standards for

BPT, BAT, NSPS, PSES, and PSNS for the Steel Forming and Finishing Subcategory as mass

limitations in pounds/1,000 pounds of product. Permit writers and control authorities shall

compute mass effluent limitations and pretreatment requirements for each forming/finishing

operation by multiplying the average daily production rate (or other reasonable measure of

production) by the respective effluent limitations guidelines or standards listed in Table 14-23. 

Production-normalized flows for the Steel Forming and Finishing Subcategory are listed in Table

14-7. Permit writers and control authorities shall not include production from unit operations

that do not generate or discharge process wastewater in the calculation of the operating rate. 

These mass-based limitations apply to the operations listed and defined in Section 14.1.5

New direct discharging facilities in the Steel Forming and Finishing Subcategory

must achieve the following performance standards. Discharges must remain within the pH range

6 to 9 and must not exceed the following.
14.0 - Effluent Limitations and Standards

14-70

Table 14-23

NSPS for the Steel Forming and Finishing Subcategory

Pollutant TSS O&G (as HEM)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0571 0.0358 0.0312 0.0239

(b) Alkaline Cleaning 0.0571 0.0358 0.0312 0.0239

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00286 0.00179 0.00156 0.00120

(e) Electroplating 0.115 0.0716 0.0623 0.00478

(f) Hot Dip Coating 0.0166 0.0104 0.00903 0.00693

(g) Lubrication 0.00137 0.000859 0.000748 0.000574

(h) Mechanical

Descaling

0.000229 0.000144 0.000125 0.0000956

(i) Painting 0.00743 0.00466 0.00405 0.00311

(j) Pressure

Deformation 

0.00286 0.00179 0.00156 0.00120

Pollutant TOC TOP

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.181 0.103 0.0188 0.00896

(b) Alkaline Cleaning 0.181 0.103 0.0188 0.00896

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00901 0.00514 0.000937 0.000448

(e) Electroplating 0.361 0.206 0.0375 0.0180

(f) Hot Dip Coating 0.0523 0.0298 0.00543 0.00260

(g) Lubrication 0.00433 0.00247 0.000450 0.000215

(h) Mechanical

Descaling

0.000721 0.000411 0.0000750 0.0000359

(i) Painting 0.0235 0.0134 0.00244 0.00117
Table 14-23 (Continued)

14.0 - Effluent Limitations and Standards

14-71

(j) Pressure

Deformation 

0.00901 0.00514 0.000937 0.000448

Pollutant Cadmium Chromium

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0000267 0.0000184 0.000355 0.000143

(b) Alkaline Cleaning 0.0000267 0.0000184 0.000355 0.000143

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00000133 0.00000092 0.0000178 0.00000714

(e) Electroplating 0.0000534 0.0000368 0.000710 0.000286

(f) Hot Dip Coating 0.00000773 0.00000533 0.000103 0.0000415

(g) Lubrication 0.00000064 0.00000044 0.00000851 0.00000343

(h) Mechanical

Descaling

0.00000011 0.00000007 0.00000142 0.00000057

(i) Painting 0.00000347 0.00000239 0.0000461 0.0000186

(j) Pressure

Deformation 

0.00000133 0.00000092 0.0000178 0.00000714

Pollutant Copper Lead

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000898 0.000327 0.0000692 0.0000517

(b) Alkaline Cleaning 0.000898 0.000327 0.0000692 0.0000517

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000449 0.0000164 0.00000346 0.00000258

(e) Electroplating 0.00180 0.000654 0.000139 0.000104

(f) Hot Dip Coating 0.000261 0.0000949 0.0000201 0.0000150

(g) Lubrication 0.0000216 0.00000785 0.00000166 0.00000124
Table 14-23 (Continued)

14.0 - Effluent Limitations and Standards

14-72

(h) Mechanical

Descaling

0.00000359 0.00000131 0.00000028 0.00000021

(i) Painting 0.000117 0.0000425 0.00000899 0.00000671

(j) Pressure

Deformation 

0.0000449 0.0000164 0.00000346 0.00000258

Pollutant Manganese Molybdenum

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000600 0.000364 0.00164 0.00103

(b) Alkaline Cleaning 0.000600 0.000364 0.00164 0.00103

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000300 0.0000182 0.0000820 0.0000511

(e) Electroplating 0.00120 0.000728 0.00328 0.00205

(f) Hot Dip Coating 0.000174 0.000106 0.000476 0.000297

(g) Lubrication 0.0000144 0.00000873 0.0000394 0.0000246

(h) Mechanical

Descaling

0.00000240 0.00000146 0.00000656 0.00000409

(i) Painting 0.0000780 0.0000473 0.000214 0.000133

(j) Pressure

Deformation 

0.0000300 0.0000182 0.0000820 0.0000511

Pollutant Nickel Silver

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00391 0.00156 0.0000955 0.0000582

(b) Alkaline Cleaning 0.00391 0.00156 0.0000955 0.0000582

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.000196 0.0000779 0.00000477 0.00000291

(e) Electroplating 0.00782 0.00312 0.000191 0.000117
Table 14-23 (Continued)

14.0 - Effluent Limitations and Standards

14-73

(f) Hot Dip Coating 0.00114 0.000452 0.0000277 0.0000169

(g) Lubrication 0.0000939 0.0000374 0.00000229 0.00000140

(h) Mechanical

Descaling

0.0000157 0.00000623 0.00000038 0.00000023

(i) Painting 0.000509 0.000203 0.0000125 0.00000756

(j) Pressure

Deformation 

0.000196 0.0000779 0.00000477 0.00000291

Pollutant Sulfide (as S) Tin

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0630 0.0267 0.0000606 0.0000453

(b) Alkaline Cleaning 0.0630 0.0267 0.0000606 0.0000453

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00315 0.00134 0.00000303 0.00000226

(e) Electroplating 0.126 0.0534 0.000122 0.0000905

(f) Hot Dip Coating 0.0183 0.00774 0.0000176 0.0000132

(g) Lubrication 0.00151 0.000641 0.00000145 0.00000109

(h) Mechanical

Descaling

0.000252 0.000107 0.00000024 0.00000018

(i) Painting 0.00818 0.00347 0.00000788 0.00000588

(j) Pressure

Deformation 

0.00315 0.00134 0.00000303 0.00000226

Pollutant Zinc

Forming/Finishing Operation

Maximum Daily

(lbs/1000 lbs of product)

Maximum Monthly Avg.

(lbs/1000 lbs of product)

(a) Acid Pickling 0.000163 0.000111

(b) Alkaline Cleaning 0.000163 0.000111

(c) Cold Forming 0 0

(d) Continuous Annealing 0.00000811 0.00000553

(e) Electroplating 0.000325 0.000222

(f) Hot Dip Coating 0.0000471 0.0000321

(g) Lubrication 0.00000389 0.00000265
Table 14-23 (Continued)

14.0 - Effluent Limitations and Standards

14-74

(h) Mechanical Descaling 0.00000065 0.00000044

(i) Painting 0.0000211 0.0000144

(j) Pressure Deformation 0.00000811 0.00000553

Pollutant Cyanide (T) Cyanide (A)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Electroplating 0.000865 0.000513 0.000580 0.000282

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Additionally, upon agreement with the permitting authority, facilities must

choose to monitor for TOP or TOC, or implement a management plan for organic chemicals as

specified in Section 15.2.7.

14.5.6 NSPS for the Oily Wastes Subcategory

EPA expects that new facilities in the Oily Wastes Subcategory will discharge

similar quantities of the same pollutants that existing sources discharge. Therefore, the need for

NSPS regulation is the same as the need for BPT regulation. (See Section 14.1.6.) 

EPA is proposing NSPS for this subcategory based on BAT Option 6, oil/water

separation by chemical emulsion breaking, gravity separation, and oil skimming. The Agency

determined that Option 6 is the best available demonstrated technology for the removal of

pollutants in this subcategory and is proposing this option for the same reasons it selected this

option for BPT and BAT. (See Section 14.1.6.)

Since EPA is proposing to set NSPS equal to BAT (Option 6) and this option is

determined to be economically achievable for these facilities under BAT, EPA concluded that

NSPS based on Option 6 would not create a barrier to entry. 

14.5.7 NSPS for the Railroad Line Maintenance Subcategory

EPA expects that new facilities in the Railroad Line Maintenance Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge. 

Therefore, the need for NSPS regulation is the same as the need for BPT regulation. (See

Section 14.1.7.) 
14.0 - Effluent Limitations and Standards

14-75

EPA is proposing NSPS for this subcategory based on BAT Option 10, DAF plus

in-process flow control and pollution prevention. The Agency determined that Option 10 is the

best available demonstrated technology for the removal of pollutants in this subcategory and is

proposing this option for the same reasons it selected this option for BPT and BAT. (See Section

14.1.7.)

EPA notes that railroad line maintenance facilities do not have revenue reported at

the facility level, and it is therefore not possible to compare costs as a percentage of facility

revenue for new and existing facilities in this subcategory. In addition, EPA is proposing to set

NSPS equal to BAT (Option 10) and has determined that this option is economically achievable

for these facilities under BAT; therefore, EPA concluded that NSPS based on Option 10 would

not create a barrier to entry. 

14.5.8 NSPS for the Shipbuilding Dry Dock Subcategory

EPA expects that new facilities in the Shipbuilding Dry Dock Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore, the

need for NSPS regulation is the same as the need for BPT regulation. (See Section 14.1.8.)

EPA is proposing NSPS for this subcategory based on BAT Option 10, DAF plus

in-process flow control and pollution prevention. The Agency determined that Option 10 is the

best available demonstrated technology for the removal of pollutants in this subcategory and is

proposing this option for the same reasons it selected this option for BPT. (See Section 14.1.8.)

Since EPA is proposing to set NSPS equal to BAT (Option 10) and has

determined that this option is economically achievable for these facilities under BAT, EPA

concluded that NSPS based on Option 10 would not create a barrier to entry.

14.6 Pretreatment Standards for New Sources (PSNS)

Section 307(c) of CWA calls for EPA to promulgate pretreatment standards for

new sources (PSNS) at the same time that it promulgates NSPS. New facilities have the

opportunity to incorporate the best available demonstrated technologies including process

changes, in-plant controls, and end-of-pipe treatment technologies. 

The same technologies discussed previously for BAT and PSES are available as

the basis for PSNS. Since new sites have the potential to install pollution prevention and

pollution control technologies more cost effectively then existing sources, EPA strongly

considered the more advanced treatment options for PSNS. The Agency discusses its analysis of

these more stringent options for PSNS on a subcategory-by-subcategory basis below. 
14.0 - Effluent Limitations and Standards

14-76

14.6.1 PSNS for the General Metals Subcategory 

EPA expects that new facilities in the General Metals Subcategory will discharge

similar quantities of the same pollutants that existing sources discharge. Therefore, the need for

PSNS regulation is the same as the need for PSES regulation. (See Section 14.4.2.) Section 7

discusses the pass-through analysis for new sources.

EPA proposes PSNS for this subcategory based on BAT Option 4 for the same

reasons it is proposing this option for NSPS. EPA is also requesting comment on basing PSNS

on Option 2, as with NSPS. In addition, EPA proposes a 1 MGY flow cutoff exclusion for

PSNS. This is the same flow cutoff level that EPA is proposing for PSES for the existing

indirect discharging facilities in the General Metals Subcategory. The Agency concluded that a 1

MGY flow cutoff is appropriate for new indirect discharging facilities in the General Metals

Subcategory based on the potential POTW permitting burden that would be associated with

developing and then maintaining permits for new sources with low flows, and the likelihood that

these facilities discharge a small amount of pound-equivalents at these low flow rates. The

Agency assumes that the pound-equivalents removed per facility for new facilities with flows

below or equal to 1 MGY would be even lower than the 22 pound-equivalents per facility for

similarly sized existing sources in this subcategory. The Agency concluded that a similar (or

even smaller) amount of pollutant removal is not significant and does not justify regulation of

these facilities by a national categorical regulation. EPA solicits comment on whether it is

appropriate to exclude new sources that discharge process wastewater equal to 1 million gallons

or less for the reasons described above.

The Agency also strongly considered proposing PSNS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. The Agency is soliciting comment and data on this PSNS option for the final rule. 

The Agency determined that the cost of compliance with PSNS based on Option 4

would make up only 0.09 percent of a new facility’s projected revenues and concluded that this

would not create a barrier to entry. 

Table 14-24 lists the proposed PSNS effluent limitations for the General Metals

Subcategory. Section 10.0 describes EPA’s data editing procedures and statistical methodology

for calculating the proposed effluent limits for this subcategory. 

Except at facilities where the process wastewater introduced into a POTW does

not exceed 1 MGY, new indirect discharging facilities in the General Metals Subcategory must

achieve the following. 
14.0 - Effluent Limitations and Standards

14-77

Table 14-24

PSNS for the General Metals Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 87 50

2. Total Organics Parameter (TOP) 9.0 4.3

3. Cadmium 0.02 0.01

4. Chromium 0.17 0.07

5. Copper 0.44 0.16

6. Total Cyanide 0.21 0.13

7. Amenable Cyanide 0.14 0.07

8. Lead 0.04 0.03

9. Manganese 0.29 0.18

10. Molybdenum 0.79 0.49

11. Nickel 1.9 0.75

12. Silver 0.05 0.03

13. Sulfide, Total 31 13

14. Tin 0.03 0.03

15. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority, 

facilities with cyanide treatment have the option of achieving the limitation for either total or 

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7. A POTW has the option of imposing mass-based standards in place of the

concentration-based standards. To convert to mass-based standards, multiply each parameter’s

concentration-based standard by the average daily flow of process wastewater discharged by the

source into the POTW.

14.6.2 PSNS for the Metal Finishing Job Shops Subcategory

EPA expects that new facilities in the Metal Finishing Job Shops Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore, the

need for PSNS regulation is the same as the need for PSES regulation (See Section 14.4.3). 

Section 7 discussed the pass-through analysis for new sources.
14.0 - Effluent Limitations and Standards

14-78

EPA is proposing PSNS for this subcategory based on BAT Option 4 for the same

reasons it is proposing this option for NSPS. EPA is also requesting comment on PSNS limits

based on Option 2. In addition, EPA is not proposing a flow cutoff exclusion for PSNS for this

subcategory for the same reasons that it did not propose a flow cutoff for PSES (See Section

14.4.3).

The Agency also strongly considered proposing PSNS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. 

The Agency determined that the cost of compliance with PSNS based on Option 4

would make up 4.64 percent of a new facility’s projected revenues and expects that this would

not create a barrier to entry. EPA notes that this is a higher percentage than for other

subcategories.

Table 14-25 lists the proposed PSNS effluent limitations for the Metal Finishing

Job Shops Subcategory. Section 10.0 describes EPA’s data editing procedures and statistical

methodology for calculating the proposed effluent limits for this subcategory. 

New indirect discharging facilities in the Metal Finishing Job Shops Subcategory

must achieve the following.

Table 14-25

PSNS for Metal Finishing Job Shops Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 78 59

2. Total Organics Parameter (TOP) 9.0 4.3

3. Cadmium 0.02 0.01

4. Chromium 0.17 0.07

5. Copper 0.44 0.16

6. Total Cyanide 0.21 0.13

7. Amenable Cyanide 0.14 0.07

8. Lead 0.04 0.03

9. Manganese 0.29 0.18

10. Molybdenum 0.79 0.49

11. Nickel 1.9 0.75
14.0 - Effluent Limitations and Standards

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

14-79

12. Silver 0.05 0.03

13. Sulfide, Total 31 13

14. Tin 0.03 0.03

15. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7. A POTW has the option of imposing mass-based standards in place of the

concentration-based standards. To convert to mass-based standards, multiply each parameter’s

concentration-based standard by the average daily flow of process wastewater discharged by the

source into the POTW.

14.6.3 PSNS for the Non-Chromium Anodizing Subcategory 

EPA expects that new facilities in the Non-Chromium Anodizing Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge and

therefore EPA is not proposing pretreatment standards for new sources for this subcategory for

the same reasons it is not proposing PSNS for this subcategory. See Section 14.4.4.

14.6.4 PSNS for the Printed Wiring Board Subcategory

EPA expects that new facilities in the Printed Wiring Board Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore, the

need for PSNS regulation is the same as the need for PSES regulation (see Section 14.4.5). 

Section 7 discusses the pass-through analysis for new sources.

EPA is proposing PSNS for this subcategory based on BAT Option 4 for the same

reasons it is proposing this option for NSPS. As was the case for PSES, EPA is not proposing a

flow cutoff exclusion for this subcategory for the same reasons discussed in Section 14.4.5.

The Agency also strongly considered proposing PSNS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. 

The Agency determined that the cost of compliance with PSNS based on Option 4

would make up only 0.20 percent of a new facility’s projected revenues and concluded that this

would not create a barrier to entry. 
14.0 - Effluent Limitations and Standards

14-80

Table 14-26 lists the proposed PSNS effluent limitations for the Printed Wiring

Board Subcategory. Section 10.0 describes EPA’s data editing procedures and statistical

methodology for calculating the proposed effluent limits for this subcategory. 

New indirect discharging facilities in the Printed Wiring Board Subcategory must

achieve the following.

Table 14-26

PSNS for the Printed Wiring Board Subcategory

Regulated Parameter

Maximum

Daily (mg/L

(ppm))

Maximum

Monthly Avg. 

(mg/L (ppm))

1. Total Organic Carbon (TOC) (as indicator) 101 67

2. Total Organics Parameter (TOP) 9.0 4.3

3. Chromium 0.17 0.07

4. Copper 0.01 0.01

5. Total Cyanide 0.21 0.13

6. Amenable Cyanide 0.14 0.07

7. Lead 0.04 0.03

8. Manganese 0.29 0.18

9. Nickel 1.9 0.75

10. Sulfide, Total 31 13

11. Tin 0.09 0.07

12. Zinc 0.08 0.06

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7. A POTW has the option of imposing mass-based standards in place of the

concentration-based standards. To convert to mass-based standards, multiply each parameter’s

concentration-based standard by the average daily flow of process wastewater discharged by the

source into the POTW.

14.6.5 PSNS for the Steel Forming and Finishing Subcategory

EPA expects that new facilities in the Steel Forming and Finishing Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge. 
14.0 - Effluent Limitations and Standards

14-81

Therefore, the need for PSNS regulation is the same as the need for PSES regulation. (See

Section 14.4.6.) Section 7 discusses the pass-through analysis for new sources.

EPA is proposing PSNS for this subcategory based on BAT Option 4 for the same

reasons it is proposing this option for NSPS. In addition, EPA is not proposing a flow cutoff

exclusion for PSNS for this subcategory for the same reasons that it did not propose a flow cutoff

for PSES. (See Section 14.4.6.)

The Agency also strongly considered proposing PSNS based on ultrafiltration for

oil and grease removal and chemical precipitation followed by sedimentation for TSS and metals

removal. This option is equivalent to BAT Option 2 with the oil/water separator replaced by an

ultrafilter. 

The Agency determined that the cost of compliance with PSNS based on Option 4

would make up only 0.17 percent of a new facility’s projected revenues and concluded that this

would not create a barrier to entry. 

EPA expresses the proposed effluent limitations guidelines and standards for

BPT, BAT, NSPS, PSES, and PSNS for the Steel Forming and Finishing Subcategory as mass

limitations in pounds/1,000 pounds of product. Permit writers and control authorities shall

compute mass effluent limitations and pretreatment requirements for each forming/finishing

operation by multiplying the average daily production rate (or other reasonable measure of

production) by the respective effluent limitations guidelines or standards listed in Table 14-27. 

Production-normalized flows for the Steel Forming and Finishing Subcategory are listed in Table

14-7. Permit writers and control authorities shall not include production from unit operations

that do not generate or discharge process wastewater in the calculation of the operating rate. 

These mass-based limitations apply to the operations listed and defined in Section 14.1.5

Table 14-27 lists the proposed PSNS effluent limitations for the Steel Forming

and Finishing Subcategory. Section 10.0 describes EPA’s data editing procedures and statistical

methodology for calculating the proposed effluent limits for this subcategory. New indirect

discharging facilities in the Steel Forming & Finishing Subcategory must achieve the following.

Table 14-27

PSNS for the Steel Forming and Finishing Subcategory

Pollutant TSS O&G (as HEM)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0571 0.0358 0.0312 0.0239
Table 14-27 (Continued)

14.0 - Effluent Limitations and Standards

Pollutant TSS O&G (as HEM)

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

14-82

(b) Alkaline Cleaning 0.0571 0.0358 0.0312 0.0239

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00286 0.00179 0.00156 0.00120

(e) Electroplating 0.115 0.0716 0.0623 0.00478

(f) Hot Dip Coating 0.0166 0.0104 0.00903 0.00693

(g) Lubrication 0.00137 0.000859 0.000748 0.000574

(h) Mechanical

Descaling

0.000229 0.000144 0.000125 0.0000956

(i) Painting 0.00743 0.00466 0.00405 0.00311

(j) Pressure

Deformation 

0.00286 0.00179 0.00156 0.00120

Pollutant TOC TOP

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.181 0.103 0.0188 0.00896

(b) Alkaline Cleaning 0.181 0.103 0.0188 0.00896

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00901 0.00514 0.000937 0.000448

(e) Electroplating 0.361 0.206 0.0375 0.0180

(f) Hot Dip Coating 0.0523 0.0298 0.00543 0.00260

(g) Lubrication 0.00433 0.00247 0.000450 0.000215

(h) Mechanical

Descaling

0.000721 0.000411 0.0000750 0.0000359

(i) Painting 0.0235 0.0134 0.00244 0.00117

(j) Pressure

Deformation 

0.00901 0.00514 0.000937 0.000448
Table 14-27 (Continued)

14.0 - Effluent Limitations and Standards

14-83

Pollutant Cadmium Chromium

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0000267 0.0000184 0.000355 0.000143

(b) Alkaline Cleaning 0.0000267 0.0000184 0.000355 0.000143

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00000133 0.00000092 0.0000178 0.00000714

(e) Electroplating 0.0000534 0.0000368 0.000710 0.000286

(f) Hot Dip Coating 0.00000773 0.00000533 0.000103 0.0000415

(g) Lubrication 0.00000064 0.00000044 0.00000851 0.00000343

(h) Mechanical

Descaling

0.00000011 0.00000007 0.00000142 0.00000057

(i) Painting 0.00000347 0.00000239 0.0000461 0.0000186

(j) Pressure

Deformation 

0.00000133 0.00000092 0.0000178 0.00000714

Pollutant Copper Lead

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000898 0.000327 0.0000692 0.0000517

(b) Alkaline Cleaning 0.000898 0.000327 0.0000692 0.0000517

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000449 0.0000164 0.00000346 0.00000258

(e) Electroplating 0.00180 0.000654 0.000139 0.000104

(f) Hot Dip Coating 0.000261 0.0000949 0.0000201 0.0000150

(g) Lubrication 0.0000216 0.00000785 0.00000166 0.00000124

(h) Mechanical

Descaling

0.00000359 0.00000131 0.00000028 0.00000021

(i) Painting 0.000117 0.0000425 0.00000899 0.00000671

(j) Pressure

Deformation 

0.0000449 0.0000164 0.00000346 0.00000258
Table 14-27 (Continued)

14.0 - Effluent Limitations and Standards

14-84

Pollutant Manganese Molybdenum

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.000600 0.000364 0.00164 0.00103

(b) Alkaline Cleaning 0.000600 0.000364 0.00164 0.00103

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.0000300 0.0000182 0.0000820 0.0000511

(e) Electroplating 0.00120 0.000728 0.00328 0.00205

(f) Hot Dip Coating 0.000174 0.000106 0.000476 0.000297

(g) Lubrication 0.0000144 0.00000873 0.0000394 0.0000246

(h) Mechanical

Descaling

0.00000240 0.00000146 0.00000656 0.00000409

(i) Painting 0.0000780 0.0000473 0.000214 0.000133

(j) Pressure

Deformation 

0.0000300 0.0000182 0.0000820 0.0000511

Pollutant Nickel Silver

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.00391 0.00156 0.0000955 0.0000582

(b) Alkaline Cleaning 0.00391 0.00156 0.0000955 0.0000582

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.000196 0.0000779 0.00000477 0.00000291

(e) Electroplating 0.00782 0.00312 0.000191 0.000117

(f) Hot Dip Coating 0.00114 0.000452 0.0000277 0.0000169

(g) Lubrication 0.0000939 0.0000374 0.00000229 0.00000140

(h) Mechanical

Descaling

0.0000157 0.00000623 0.00000038 0.00000023

(i) Painting 0.000509 0.000203 0.0000125 0.00000756

(j) Pressure

Deformation 

0.000196 0.0000779 0.00000477 0.00000291
Table 14-27 (Continued)

14.0 - Effluent Limitations and Standards

14-85

Pollutant Sulfide (as S) Tin

Forming/Finishing

Operation

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

Maximum Daily

(lbs/1000 lbs of

product)

Maximum

Monthly Avg.

(lbs/1000 lbs of

product)

(a) Acid Pickling 0.0630 0.0267 0.0000606 0.0000453

(b) Alkaline Cleaning 0.0630 0.0267 0.0000606 0.0000453

(c) Cold Forming 0 0 0 0

(d) Continuous

Annealing

0.00315 0.00134 0.00000303 0.00000226

(e) Electroplating 0.126 0.0534 0.000122 0.0000905

(f) Hot Dip Coating 0.0183 0.00774 0.0000176 0.0000132

(g) Lubrication 0.00151 0.000641 0.00000145 0.00000109

(h) Mechanical

Descaling

0.000252 0.000107 0.00000024 0.00000018

(i) Painting 0.00818 0.00347 0.00000788 0.00000588

(j) Pressure

Deformation 

0.00315 0.00134 0.00000303 0.00000226

Pollutant Zinc

Forming/Finishing Operation

Maximum Daily

(lbs/1000 lbs of product)

Maximum Monthly Avg.

(lbs/1000 lbs of product)

(a) Acid Pickling 0.000163 0.000111

(b) Alkaline Cleaning 0.000163 0.000111

(c) Cold Forming 0 0

(d) Continuous Annealing 0.00000811 0.00000553

(e) Electroplating 0.000325 0.000222

(f) Hot Dip Coating 0.0000471 0.0000321

(g) Lubrication 0.00000389 0.00000265

(h) Mechanical Descaling 0.00000065 0.00000044

(i) Painting 0.0000211 0.0000144

(j) Pressure Deformation 0.00000811 0.00000553

As discussed in Section 15.2.7, upon agreement with the permitting authority,

facilities with cyanide treatment have the option of achieving the limitation for either total or

amenable cyanide. Upon agreement with the permitting authority, facilities must choose to
14.0 - Effluent Limitations and Standards

14-86

monitor for TOP or TOC, or implement a management plan for organic chemicals as specified in

Section 15.2.7.

14.6.6 PSNS for the Oily Wastes Subcategory

EPA expects that new facilities in the Oily Wastes Subcategory will discharge

similar quantities of the same pollutants that existing sources discharge. Therefore, the need for

PSNS regulation is the same as the need for PSES regulation. (See Section 14.4.7.). Section 7

discusses the pass-through analysis for new sources.

EPA is proposing PSNS for this subcategory based on BAT Option 6 for the same

reasons it is proposing this option for NSPS. In addition, EPA is proposing a 2 MGY flow cutoff

exclusion for PSNS with serious consideration of a 3 MGY flow cutoff as well. This is the same

flow cutoff level that EPA is proposing for PSES for the existing indirect discharging facilities in

the Oily Wastes Subcategory. The Agency is proposing a 2 MGY flow cutoff is appropriate for

new indirect discharging facilities in the Oily Wastes Subcategory based on the potential POTW

permitting burden that would be associated with developing and then maintaining permits for

new sources with low flows, and the likelihood that these facilities discharge a small amount of

pound-equivalents at these low flow rates. The Agency assumes that the pound-equivalents per

facility for new facilities with flows below or equal to 2 MGY would be even lower than the 2

pound-equivalents per facility for similarly sized existing sources in this subcategory. The

Agency concluded that a similar (or even smaller) amount of pollutant removal is not justified by

the cost of the regulation for new indirect oily waste facilities discharging less than or equal to 2

MGY. 

Since EPA is proposing to set PSNS equal to PSES (Option 6) and this option is

determined to be economically achievable for these facilities under PSES, the Agency concluded

that this would not create a barrier to entry. 

14.6.7 PSNS for the Railroad Line Maintenance Subcategory

EPA expects that new facilities in the Railroad Line Maintenance Subcategory

will discharge similar quantities of the same pollutants that existing sources discharge. 

Therefore, EPA is proposing not to establish PSNS for this subcategory for the same reasons that

it did not propose PSES. (See Section 14.4.8.)

14.6.8 PSNS for the Shipbuilding Dry Dock Subcategory 

EPA expects that new facilities in the Shipbuilding Dry Dock Subcategory will

discharge similar quantities of the same pollutants that existing sources discharge. Therefore,

EPA is proposing not to establish PSNS for this subcategory for the same reasons that it did not

propose PSES. (See Section 14.4.9.)
14.0 - Effluent Limitations and Standards

14-87

Appendix A

Pollution Prevention Alternative for the Metal Finishing Job Shops Subcategory

Introduction

The Agency is considering allowing indirect discharge facilities in the Metal Finishing

Job Shops subcategory, with approval by their control authority (e.g., POTW), to demonstrate

compliance with specified pollution prevention and water conservation practices (in addition to

maintaining compliance with the existing Metal Finishing and Electroplating Effluent Guidelines

or approved local water quality-based limits, whichever is more stringent) in lieu of meeting the

requirements of the MP&M regulation. Facilities in the Metal Finishing Job Shops subcategory

that do not wish to use the compliance alternative would need to meet the full requirements of

the MP&M regulation as specified in today’s proposed rule. 

EPA has solicited comment on whether to allow all facilities in the Metal Finishing Job

Shops subcategory to comply with the P2 Alternative or whether the P2 Alternative should only

be available to facilities below a specified wastewater discharge volume. EPA has proposed low

flow exclusions for indirect dischargers in the General Metals (1 MGY) and Oily Wastes (2

MGY) subcategories due to potential permitting burden on POTWs.

Background

The proposed pollution prevention alternative for the Metal Finishing Job Shops

Subcategory grew out of the National Metal Finishing Strategic Goals Program (“SGP”). The

SGP was developed out of EPA’s sector based Common Sense Initiative. In 1994, EPA

launched the CSI to promote “cleaner, cheaper, and smarter” environmental performance, using a

non-adversarial, stakeholder consensus process to test innovative ideas and approaches. The

SGP is a cooperative effort that involves all stakeholders (e.g., industry, regulators,

environmental/citizen groups) to define a fundamentally different approach to environmental and

public health protection by exploring a more flexible, cost-effective and environmentally

protective solutions tailored to specific industry needs. The Metal Finishing SGP is a

performance-based, voluntary program which includes commitments by the industry to meet

multimedia environmental targets substantially reducing pollution from their operations beyond

what is required by law. These goals will conserve water, energy and metals, and reduce

hazardous emissions. The other stakeholders in this process (EPA, State and local regulators,

and environmental/community groups) have also committed to working with the industry

participants to help them meet their goals through compliance, technical, and financial assistance,

removing regulatory and policy barriers, offering incentives, and an open dialogue as issues arise. 

The SGP represents a long-term strategic vision for improved environmental protection

by the entire metal finishing industry. The metal finishing industry’s tangible commitment to

work with the Agency lays the foundation for this pollution prevention (P2) compliance

alternative.
14.0 - Effluent Limitations and Standards

14-88

Pollution Prevention Alternative Plan

The purpose of a pollution prevention compliance alternative (“P2 Alternative”) is to

reduce economic impacts on the facilities in the Metal Finishing Job Shops subcategory and to

take into consideration the activities and achievements of this Common Sense Initiative (“CSI”)

sector to test innovative approaches to environmental protection, which has culminated in the

National Metal Finishing Strategic Goals Program.

One way that EPA is considering to specify pollution prevention and water conservation

practices, without stifling innovation and advances, is to require facilities to choose practices

from a larger list (or menu) of categories of specified practices (see below). EPA is considering

requiring practices in all ten categories. The following is an example of the format and potential

pollution prevention practices that EPA is considering for incorporation into the final MP&M

rule:

Category 1. Must Use Practices that Reduce and/or Recover Drag-Out

To satisfy this requirement, facilities must implement three or more drag-out reduction practices

or use at least one drag-out recovery (i.e., chemical recovery) technology listed below on all

electroplating or surface finishing lines.

Drag-out Reduction Practices

C Lower process solution viscosity and/or surface tension by lowering chemical

concentration, increasing bath temperature, or use wetting agents.

C Reduce drag-out volume by modifying rack/barrel design and perform rack maintenance 

to avoid solution trapping under insulation.

C Position parts on racks in a manner that avoids trapping solution.

C Reduce speed of rack/barrel withdraw from process solution and/or increase dwell time

over process tank.

C Rotate barrels over process tank to improve drainage.

C Use spray/fog rinsing over the process tank (limited applicability).

C Use drip boards and return process solution to the process tank.

C Use drag-out tanks, where applicable, and return solution to the process tank.

C Work with customers to ensure that part design maximizes drainage

Drag-out Recovery

Use a chemical recovery technology to recover drag-out from wastewater.

C Evaporators

C Ion exchange

C Electrowinning

C Electrodialysis

C Reverse osmosis
14.0 - Effluent Limitations and Standards

14-89

Category 2. Must Use Good Rinse System Design for Water Conservation

To satisfy this requirement, facilities must implement three or more elements of good rinse

system design listed below on all electroplating or surface finishing lines: 

C Select the minimum size rinse tank in which the parts can be rinsed and use the same size

for the entire plating line, where practical.

C Locate the water inlet and discharge points of the tank at opposite positions in the tank to

avoid short-circuiting or use a flow distributor to feed the rinse water evenly.

C Use air agitation, mechanical mixing or other means of turbulence.

C Use spray/fog rinsing (less effective with hidden surfaces).

C Use multiple rinse tanks in a counter-flow configuration (i.e., counter-current cascade

rinsing).

C Reuse rinse water multiple times in different rinse tanks for succeeding less critical

rinsing

Category 3. Must Use Water Flow Control for Water Conservation

To satisfy this requirement, facilities must implement at least one effective method of water use

control on all electroplating or surface finishing lines. Effective water use controls include, but

are not limited to: 

C Flow restrictors (Flow restrictors as a stand alone method of rinse water control are only

effective with plating lines that have constant production rates, such as automatic plating

machines. For other operations, there must also be a mechanism or procedure for

stopping water flow during idle periods.)

C Conductivity controls

C Timer rinse controls

C Production activated control (e.g., spray systems activated when a rack or barrel

enters/exits a rinse station.)

Category 4. Must Segregate Non-Process Water from Process Water

To satisfy this requirement, facilities must not combine non-process water such as non-contact

cooling water with process wastewater prior to wastewater treatment.

Category 5. Must Use Water Conservation Practices with Air Pollution Control Devices

To satisfy this requirement, facilities operating air pollution control devices with wet scrubbers

must recirculate the scrubber water as appropriate (periodic blowdown is allowed, as needed). 

Where feasible, reuse scrubber water in process baths.

Category 6. Must Practice Good Housekeeping

To satisfy this requirement, facilities must demonstrate compliance with each of the requirements

listed below:

C Perform preventative maintenance on all valves and fittings (i.e., check for leaks and

damage) and repair leaky valves and fittings in a timely manner.

C Inspect tanks and liners and repair or replace equipment as necessary to prevent ruptures

and leaks. Use tank and liner materials that are appropriate for associated process

solutions.
14.0 - Effluent Limitations and Standards

14-90

C Perform quick cleanup of leaks and spills in chemical storage and process areas.

C Remove metal buildup from racks and fixtures.

Category 7. Minimize the Entry of Oil Into Rinse Systems

To satisfy this requirement, facilities must do at least one of the practices listed below:

C Minimize the entry of oil into cleaning baths or use oil skimmers or other oil removal

devices in cleaning baths when needed to prevent oil from entering rinse tanks.

C Work with customers to degrease parts prior to shipment to the plating facility to

minimize the amount of oils on incoming materials.

Category 8. Must Sweep or Vacuum Dry Production Areas Prior to Rinsing with Water

To satisfy this requirement, facilities must sweep or vacuum dry production area floors prior to

rinsing with water. 

Category 9. Must Reuse Drum/Shipping Container Rinsate Directly in Process Tanks

To satisfy this requirement, when performing rinsing of raw material drums, storage drums,

and/or shipping containers that contain pollutants regulated under the MP&M regulation,

facilities must reuse the rinsate directly into process tanks or save for use in future production.

Category 10. Must Implement Environmental Management and Record Keeping System

To satisfy this requirement, facilities must meet the requirements listed below:

C Implement an environmental management program that includes, but is not limited to, the

following elements: 

C pollution prevention policy statement, 

C environmental performance goals, 

C pollution prevention assessment, 

C pollution prevention plan, 

C environmental tracking and record keeping system,

C procedures to optimize control parameter settings (e.g., ORP set point in cyanide

destruction systems, optimum pH for chemical precipitation systems, etc.), and 

C statement delineating minimum training levels for wastewater treatment operators.

(EPA notes that it has developed a template for a metal finishing facility-specific Environmental

Management System that is being used in conjunction with the SGP in EPA’s Region 9 in

California– see http://www.strategicgoals.org/tools/home.htm for information on this template). 

The first two categories listed above involve practices and techniques for reducing dragout. Drag-out is the film of chemical solution covering parts and fixtures as they exit process

solutions. For many metal finishing operations, drag-out and the subsequent contamination of

rinse waters is the major pollution control challenge. Reducing the formation of drag-out,

minimizing the introduction of drag-out to rinse systems, and recovering drag-out are important

pollution prevention measures. EPA believes that drag-out reduction and recovery may prevent a

substantial pollutant loading of metals from being discharged to the POTW However, EPA did

not have sufficient information on the pollutant reductions, capital costs, and operating and
14.0 - Effluent Limitations and Standards

14-91

maintenance costs associated with installation and operation of drag-out reduction and recovery

technologies to include such equipment explicitly into the model that EPA uses to develop

national estimates of compliance costs and pollutant reductions. Some aspects of drag-out

reduction are captured in the flow rinse reduction modules of the cost and loadings model (see

Section 11 for a detailed discussion of the cost and loadings model). Good rinse design can

reduce contamination of rinse water as well as reduce the volume of fresh water needed to

perform the necessary rinsing. It also reduces the volume of wastewater requiring treatment,

which in turn reduces costs and the volume of wastewater treatment sludge requiring disposal. 

EPA specifically solicits data on the pollutant reductions, capital costs, and operating and

maintenance costs associated with installation and operation of drag-out reduction and recovery

technologies.

EPA is considering allowing facilities complying with the P2 Alternative to substitute

another pollution prevention practice for one listed above provided that the facility provides

adequate justification for the modification in a written request submitted to the control authority. 

Facility owners must certify compliance with the pollution prevention requirements twice per

year and maintain records at the facility indicating how each category requirement has been

satisfied. Facilities choosing the P2 Alternative would also need to agree to make the practices

enforceable. Reporting would occur in conjunction with their twice annual periodic reports on

continued compliance under the General Pretreatment Regulations (40 CFR 403.12(e)). 

EPA has solicited comment on all aspects of the Pollution Prevention Alternative for the

Metal Finishing Job Shops subcategory including the list of practices as well as the possible

format for the alternative. More specifically, EPA requested comment on whether there are

additional practices that should be listed, the costs of implementing this compliance alternative,

the pollutant reduction associated with this alternative, and whether EPA should offer this

alternative to other subcategories (even those not currently regulated by the Metal Finishing and

Electroplating effluent guidelines). EPA also requested comments from local regulators on the

implementation burden, the required documentation, and on the ability to enforce a P2

Alternative.
15.0 - Permitting Guidance

15-1

15.0 PERMITTING GUIDANCE

This section provides guidance to permit writers and control authorities (e.g.,

POTWs) in implementing the MP&M effluent guidelines. In particular, this section provides

permit writers and control authorities with information and data that can be useful in converting

concentration-based limitations to mass-based limitations. As explained later in this section,

EPA is not proposing mass-based limitations for any of the MP&M subcategories except for the

Steel Forming and Finishing Subcategory. However, EPA recommends that permit writers or

control authorities evaluate a facility’s water use and develop mass-based limits in cases where a

facility does not have sufficient water conservation practices in place. This section provides

permit writers and control authorities with the tools to assess a facility’s water conservation

practices. 

The MP&M category covers sites that generate and discharge wastewater while

manufacturing, assembling, rebuilding, repairing, and maintaining metal parts, metal products,

and machinery for use in one or more of the following industrial sectors: aerospace, aircraft, bus

and truck, electronic equipment, hardware, household equipment, instruments, job shops, mobile

industrial equipment, motor vehicles, office machines, ordnance, precious metals and jewelry,

printed wiring boards, railroad, ships and boats, stationary industrial equipment, and

miscellaneous metal products. The MP&M category includes state and local government

facilities that manufacture, maintain, or rebuild metal parts, products, or machines (e.g., a town

that operates its own bus, truck, and/or snow removal equipment maintenance facility). MP&M

effluent guidelines also cover federal facilities or other mixed-use facilities that manufacture,

maintain, or rebuild metal parts, products or machines (e.g., U.S. naval shipyards). 

EPA is proposing limitations and standards for 8 subcategories of facilities

(covering all 18 industrial sectors). Section 6.0 of this document discusses the proposed

subcategorization scheme. 

Section 15.1 provides background on the MP&M effluent guidelines. Section

15.2 provides basic guidance on implementing the MP&M effluent guidelines. Sections 15.3

through 15.6 present guidance on determining pollution prevention and water conservation

practices for the major wastewater-generating unit operations performed at MP&M sites. Tables

15-1 through 15-9 and all figures are located at the end of the section.

15.1 Background

EPA has established effluent guidelines for 13 industrial categories that may

perform operations that are sometimes found in MP&M facilities. These effluent guidelines are:

C Electroplating (40 CFR Part 413);

C Iron & Steel Manufacturing (40 CFR Part 420);

C Nonferrous Metals Manufacturing (40 CFR Part 421);

C Ferroalloy Manufacturing (40 CFR Part 424);
15.0 - Permitting Guidance

15-2

C Metal Finishing (40 CFR Part 433);

C Battery Manufacturing (40 CFR Part 461);

C Metal Molding & Casting (40 CFR Part 464);

C Coil Coating (40 CFR Part 465);

C Porcelain Enameling (40 CFR Part 466);

C Aluminum Forming (40 CFR Part 467);

C Copper Forming (40 CFR Part 468);

C Electrical & Electronic Components (40 CFR Part 469); and

C Nonferrous Metals Forming & Metal Powders (40 CFR Part 471).

In 1986, the Agency reviewed coverage of these regulations and identified a

significant number of metals processing facilities discharging wastewater not covered under

these 13 regulations. Based on this review, EPA performed a more detailed analysis of these

unregulated sites and identified the discharge of significant amounts of pollutants. This analysis

resulted in the formation of the “Metal Products and Machinery” (MP&M) category. 

EPA recognizes that, in some cases, unit operations performed in industries

covered by the existing effluent guidelines are the same as unit operations performed at MP&M

facilities. In general, when unit operations and their associated wastewater discharges are already

covered by an existing effluent guideline, they will remain covered under that effluent guideline. 

However, many facilities that are covered by the existing Electroplating (40 CFR 413) and Metal

Finishing (40 CFR 433) effluent guidelines will now be covered by MP&M. EPA notes that the

proposed MP&M rule amends the applicability of 40 CFR Parts 413, 433, 464, 467 and 471 to

clarify coverage as it relates to facilities covered by the MP&M rule. Section 1 discusses the

applicability of the MP&M rule, including the overlap with existing regulations.

When a facility covered by an existing metals effluent guideline (other than

Electroplating or Metal Finishing) discharges wastewater from unit operations not covered under

that existing metals guideline but covered under MP&M, the facility will need to comply with

both regulations. In those cases, the permit writer or control authority (e.g., POTW) will

combine the limitations using an approach that proportions the limitations based on the different

production levels (for production-based standards) or wastewater flows (for concentration-based

standards). POTWs refer to this approach as the “combined wastestream formula” (40 CFR

403.6(e)), while NPDES permit writers refer to it as the “building block approach.” Application

of the combined wastestream formula can be found in EPA’s Guidance Manual For the Use of

Production-Based Pretreatment Standards and the Combined Wastestream Formula (24). Other

references which can be used by the permit writer or control authority include EPA’s Guidance

Manual for Electroplating and Metal Finishing Pretreatment Standards (25), and EPA’s NPDES

Permit Writers’ Manual (26). Section 15.2 discusses the combined wastestream formula in

more detail. In addition, Section 15.2 discusses several monitoring alternatives which EPA has

proposed to reduce burden on MP&M facilities.

As discussed in Section 14.0, the MP&M effluent limitations guidelines and standards consist of

concentration-based limitations for seven subcategories and mass-based limitations for one
15.0 - Permitting Guidance

15-3

subcategory. EPA defines the MP&M subcategories in Section 6. Concentration-based limits

apply to the following dischargers:

C Existing and new direct and indirect discharging Printed Wiring Board

subcategory facilities;

C Existing and new direct and indirect discharging Metal Finishing Job 

Shops subcategory facilities;

C Existing and new direct discharging Railroad Line Maintenance

subcategory facilities;

C Existing and new direct discharging Shipbuilding Dry Dock subcategory

facilities;

C Existing and new direct discharging Non-Chromium Anodizing

subcategory facilities;

C Existing and new direct discharging General Metals subcategory facilities;

C Existing and new indirect discharging General Metals subcategory

facilities with flows greater than one million gallons per year of process

wastewater;

C Existing and new direct discharging Oily Waste subcategory facilities; and

C Existing and new indirect discharging Oily Waste subcategory facilities

with flows greater than two million gallons per year of process wastewater. 

Mass-based limitations apply to:

C Existing and new direct and indirect discharging Steel Forming and

Finishing subcategory facilities. 

EPA is proposing mass-based limitations (instead of concentration based

limitations) for direct and indirect discharging Steel Forming and Finishing subcategory facilities

for several reasons. First, NPDES regulations (40CFR Part 122.45(f)) require permit writers to

implement mass-based limits for direct dischargers and the General Pretreatment Standards

(40CFR Part 403.6(d)) provides that the control authority may impose mass-based limitations on

industrial users when appropriate. In the case of facilities in the Steel Forming and Finishing

subcategory, EPA already regulates wastewater discharges from these facilities under 40CFR

Part 420 using mass-based limits. As a result, these facilities are already accustomed to tracking

their production rate (i.e., tons of product produced per day). Because of the uniform nature of

the steel products produced by Steel Forming and Finishing facilities (wire, rod, bars, pipe, or

tube), facilities in this subcategory can track the weight of product produced in a relatively

straight forward manner. One of the primary reasons that EPA is not proposing mass-based

limitations for other subcategories is the fact that most MP&M facilities do not collect

production information on a wastestream-by-wastestream basis, and therefore development of

mass-based limitations could create a significant burden for the permit writer, control authority,

and the MP&M facility. (See Section 15.2.3 for a discussion on implementing the Steel

Forming and Finishing mass-based limits).
15.0 - Permitting Guidance

15-4

The following facilities are excluded from this regulation: existing and new

indirect dischargers from the General Metals Subcategory that discharge less than or equal to one

million gallons per year of process wastewater; existing and new indirect dischargers from the

Oily Wastes Subcategory that discharge less than or equal to two million gallons per year of

process wastewater; existing and new indirect discharging Railroad Line Maintenance

subcategory facilities; existing and new indirect discharging Shipbuilding Dry Dock subcategory

facilities; and existing and new indirect discharging Non-Chromium Anodizing subcategory

facilities. Existing and new indirect discharging Non-Chromium Anodizing subcategory

facilities remain covered by the electroplating (40 CFR Part 413) and metal finishing (40 CFR

Part 433) effluent guidelines, as applicable. 

As mentioned above, EPA is not proposing that permit writers or control

authorities implement the MP&M limits on a mass basis except for the Steel Forming and

Finishing Subcategory. However, EPA recommends that permit writers or control authorities

evaluate a facility’s water use and develop mass-based limits when a facility does not have

sufficient water conservation practices. At 40 CFR 122.45(f), EPA requires permit writers to

implement mass-based limitations for direct dischargers, but the NPDES regulations allow an

exception when the limits are expressed in terms of other units of measurement (e.g.,

concentration). Section 403.6(d) of the CWA provides that the control authority may impose

mass-based limitations on industrial users which are using dilution to meet applicable

pretreatment requirements or where mass-based limitations is appropriate. Sections 15.3 through

15.6 provide permit writers and control authorities with the tools to assess a facility’s water

conservation practices. 

For MP&M facilities that have good water conservation practices, the

concentration-based effluent limitations may be sufficient. Sections 15.3 through 15.6 provide

the permit writer or control authority with methodologies to determine if sites are complying with

the concentration-based effluent limits without increasing process water usage (i.e., dilution). 

For MP&M facilities that do not have good water conservation practices, the permit writer or

control authority can use the information provided in this section to develop mass-based

limitations. EPA believes that this approach will reduce the implementation burden associated

with establishing mass-based limitations for all MP&M facilities, and will still increase use of

water conservation practices at the facilities where it is most appropriate. EPA anticipates that

MP&M facilities that have been using the best pollution prevention and water conservation

practices may request that the permit writer or POTW use mass-based limits in their permits. 

EPA based the proposed concentration-based MP&M effluent limitations on a

technology train consisting of in-process pollution prevention and flow-reduction technologies

followed by end-of-pipe treatment. The in-process technologies include: conductivity meters,

flow restrictors, and countercurrent cascade rinsing for flowing rinses; at-the-source machine

coolant recycling; and at-the-source paint curtain recycling. The end-of-pipe treatment for the

five metal-bearing subcategories include pretreatment steps such as chromium reduction, cyanide

destruction, oil/water separation, and chelated metals treatment, followed by chemical

precipitation with solids removal. The end-of-pipe treatment for the Oily Wastes Subcategory is
15.0 - Permitting Guidance

15-5

chemical emulsion breaking and oil water separation and the end-of-pipe treatment for the

Railroad Line Maintenance and Shipbuilding and Dry Docks Subcategory is dissolved air

flotation. Section 9.0 discusses in detail the treatment technology options for various

subcategories. EPA’s effluent limitations guidelines and standards do not require that a

discharger (or POTW industrial user) install any prescribed treatment system to comply with the

limitations and standards. Facility operators are free to choose any mechanism or combination of

treatment options they wish, including sending process wastewater off-site for treatment, so long

as the operator does not discharge (or introduce to a POTW) wastewater in violation of EPA’s

limitations and standards. 

EPA is proposing to establish a three-year deadline (from the date of publication

of the final MP&M rule) for compliance with the MP&M pretreatment standards for existing

sources (PSES). EPA is proposing a three-year deadline because design and construction of

systems adequate for compliance with PSES will be a substantial undertaking for many MP&M

sites. In addition, control authorities (e.g., POTWs) will need the time to develop the permits or

other control mechanisms for their industrial users. Once EPA finalizes the MP&M rule, these

limitations will be reflected in NPDES permits issued to direct dischargers. New sources must

comply with the new source standards and limitations (PSNS and NSPS) of the MP&M rule

(once it is finalized) at the time they commence discharging MP&M process wastewater. 

Because the final rule is not expected within 120 days of the proposed rule, the Agency considers

a discharger a new source if its construction commences following promulgation of the final rule

(40 CFR 122.2; 40 CFR 403.3). In addition, the current MP&M proposal notice fully replaces

the MP&M Phase I proposal, published on May 30, 1995. Therefore, compliance deadlines in

that proposal would obviously no longer apply.

15.2 Implementing the MP&M Effluent Guidelines

Once the permit writer or control authority determines applicability and the

appropriate subcategory for a site (see Section 6), EPA suggests that the permit writer or control

authority conduct a process-water-use analysis to determine if the site currently implements

sufficient pollution prevention and water conservation practices. Figure 15-1 outlines the

decision making steps for the process-water-use analysis. EPA defines process wastewater as

any water that, during manufacturing, rebuilding, or maintenance, comes into direct contact with

or results from the production or use of any raw materials, intermediate product, finished

product, by-product, or waste product. The Agency does not consider noncontact cooling water a

process wastewater. However, it does consider wastewater from the operation of air pollution

control equipment used in MP&M process areas process wastewater. (See Section 1.3 for a

discussion of the applicability of wastewater streams.)

Section 15.2.3 describes the use and appropriateness of historical flow data to

calculate mass-based limitations while Section 15.2.4 describes the use of EPA’s flow data from

MP&M surveys to develop mass-based limits. The Agency recommends that the permit writer or

control authority use historical flow data only when converting concentration-based limits for a

site that has demonstrated pollution prevention and water conservation practices in place (e.g.,
15.0 - Permitting Guidance

15-6

on-demand countercurrent cascade rinses, in-process metal recovery, recycling of machining

coolants) for unit operations contributing most of the site’s flow. A site with good pollution

prevention and water conservation practices may request that their discharge permit or control

mechanism contain mass-based limits. Section 15.2.7 discusses several proposed flexible

monitoring alternatives that are expected to reduce burden. Sections 15.3 through 15.6 discuss

examples of common pollution prevention and water conservation practices applicable to the

major wastewater-generating MP&M operations. These sections also provide information for

assessing the performance of these practices at MP&M sites. 

Unit operations typically contributing the majority of the flow from a MP&M site

are:

C Surface treatment rinses (e.g., acid and alkaline treatment rinsing,

electroplating rinsing, anodizing rinsing, and chemical conversion coating

rinsing);

C Machining operations;

C Painting operations; and

C Cleaning operations.

These operations produce approximately 77 percent of the wastewater generated by MP&M sites. 

EPA estimates that approximately 96 percent of the 10,300 MP&M wastewater-discharging sites

perform one or more of these operations. For facilities that do not have sufficient pollution

prevention and water conservation practices in place, EPA recommends that the permit writer or

control authority use best professional judgment (BPJ) when converting from the concentrationbased limits to mass-based limits. Sections 15.2.4 and 15.3 contain information that will be

helpful in using BPJ for this purpose.
15.0 - Permitting Guidance

1

EPA notes that if a facility that has wastewater that falls under the Oily Wastes Subcategory and wastewater under

the General Metals Subcategory the facility would be covered by the General Metals limits only, unless the site

treats the wastewater in separate wastewater treatment systems.

15-7

15.2.1 Application of the Building Block Approach for Direct Dischargers

For instances where a direct discharger is covered by multiple categorical

standards (e.g., MP&M, Iron and Steel - 40 CFR Part 420, and Aluminum Forming - 40 CFR

Part 467) or multiple subcategories1 within MP&M, the NPDES permit writer must apply the

limits from each categorical standard (and/or MP&M subcategory) to derive the effluent limits

for the facility. If a facility combines all wastewater regulated by the various effluent guidelines

prior to treatment or discharge to surface waters, then the permit writer would combine the

allowable pollutant concentrations or loadings for each subcategory (proportioning the flow or

load appropriately) to arrive at a single, combined set of technology-based effluent limits for the

facility - the “building block” approach (24). In circumstances where a facility combines a

wastestream for which a particular pollutant is not regulated by the applicable categorical

standard with another wastestream for which the pollutant is regulated, then the permit writer

must ensure that the stream that does not contain the regulated pollutant does not dilute the

stream containing the regulated pollutant to the point where the pollutant is not analytically

detectable. If this occurs, then federal regulations at 40 CFR Part 122.45(h) authorize the permit

writer to establish internal monitoring points.
15.0 - Permitting Guidance

15-8

Figure 15-1. MP&M Permitting Process Flow Chart
15.0 - Permitting Guidance

15-9

The equation below describes the flow-weighted building block approach for

calculating concentration-based daily maximum limits.

CT' j (15-1)

FL

FT

× CL

where:

CT = The alternate concentration limit for the combined wastestream

(mg/L);

CL = The categorical effluent limitation concentration limit for a

pollutant in the regulated stream (mg/L);

FL = The average daily flow of stream (L/day); and

FT = The total daily flow of all combined streams (L/day). 

To use the building block approach (and combined wastestream formula) to arrive at a single set

of technology-based effluent limits for the facility, the permit writer or control authority can use

the following steps:

Step 1. Determine the concentration-based or mass-based limits for each industrial category. 

Step 2. Determine the flow rates for the unit operations in each industrial category. For facilities

with good pollution prevention and water conservation practices in place, flow rates can be

estimated from historical flow data. For facilities without good pollution prevention and water

conservation practices in place, the permit writer or control authority can estimate flows using

the production normalized flows (PNFs) provided in Table 15-1 and can make a reasonable

estimate of production (see Section 15.2.4). 

Step 3. Multiply the concentration-based limit (mg/L) from each industrial category by the flow

rate (L/day) from the industrial category to determine a daily mass (mg/day). Sum the daily mass

from each category and divide by the total combined flow rate at the monitoring point. 

The following is an example showing how the building block approach can be used to calculate

an effluent limit for nickel when two categorical wastewaters are combined in a single treatment

system. 

Example 1

A household equipment manufacturer has effluent limitations for nickel under two categorical

standards (MP&M and Porcelain Enameling (40 CFR Part 466)), and combines each wastestream

in a single wastewater treatment system. Assuming the facility has good pollution prevention and

water conservation practices in place, the maximum daily limit for nickel following treatment

would be calculated as follows:
15.0 - Permitting Guidance

1Production-based BAT nickel limit for porcelain enameling (coating operation) is 0.37 lbs/1 million ft2

 (40 CFR

Part 466) 

15-10

75,700 L/day

75,700 L/day % 151,400 L/day

× 0.5 mg/L %

151,400 L/day

75,700 L/day % 151,400 L/day

× 0.67 mg/L

MP&M General Metals maximum daily Nickel limit: 0.5 mg/L, example flow: 75,700 L/day 

 (20,000 gal/day)

Part 466 maximum daily Nickel limit1: 0.37 lbs/1 million ft2 (coating), example 

flow: 151,400 L/day (40,000 gal/day), 

example coating throughput: 600,000 ft2/day. 

Part 466 maximum daily Nickel concentration:

 0.37 lbs/1 million ft2

 × 0.6 million ft2/day × 1,000,000 mg/kg 

 2.2 lbs/kg × 151,400 L/day

Nickel concentration: 0.67 mg/L

Combined MP&M and Part 466 Nickel concentration (daily max) = 

Combined Nickel concentration limit (daily max) = 0.17 + 0.45 = 0.62 mg/L

15.2.2 Application of the Combined Wastestream Formula for Indirect Dischargers

When a facility has multiple categorical effluent limitations and discharges to a

POTW, the control authority must apply the combined wastestream formula (40 CFR Part

403.6(e)) to calculate the pretreatment standards. The combined wastestream formula is based

on three types of waste streams that can exist at an industrial facility: regulated, unregulated, and

dilute. A regulated wastestream from an industrial process is regulated by a categorical

pretreatment standard for a pollutant. An unregulated wastestream is not covered by a

categorical pretreatment standard and is not classified as a dilute stream, or is not regulated for

the pollutant in question, although it is regulated for others. A dilute stream includes sanitary

wastewater, noncontact cooling water and boiler blowdown, and waste streams listed in

Appendix D to 40 CFR Part 403.

According to 40 CFR Part 403, the combined wastestream formula is:

CT' (15-2)

j CI

FI

j FI

×

FT& FD

FT

where:

CT = The alternate concentration limit for the combined wastestream

(mg/L);
15.0 - Permitting Guidance

15-11

CI = The categorical pretreatment standard concentration limit for a

pollutant in the regulated stream I (mg/L);

FI = The average daily flow of stream I (L/day);

FD = The average daily flow from dilute waste streams as defined in 40

CFR Part 403 (L/day); and

FT = The total daily flow (L/day). 

As described in 40 CFR Part 403, the methodology for developing combined

wastestream formula daily maximum limits is essentially the same as the methodology for the

“building block” approach used for direct dischargers (24). If a site combines wastewater

regulated by multiple pretreatment standards prior to treatment or discharge to a POTW, then the

control authority would combine the allowable pollutant concentrations or loadings for each

category (proportioning the flow appropriately) to arrive at a single set of technology-based

pretreatment standards for the facility. 

Like the building block approach, the permit writer or control authority can also

use the combined wastestream formula on mass-based limitations. The example below shows

how to calculate a mass-based limit for zinc when multiple categorical wastewaters are

combined. 

Example 2

A household equipment manufacturer with good water conservation practices in place, combines

wastewater from the MP&M General Metals subcategory, the Porcelain Enameling category, and

the Copper Forming category at an on-site chemical precipitation and clarification wastewater

treatment system. Effluent from the treatment system is combined with sanitary wastewater at

the outfall to the POTW.

Industrial Category Wastestream Type

Historical Flow

(mgd) Zn Limit (mg/L)

MP&M General Metals Regulated 0.1 0.38

Porcelain Enameling

(Steel-coating Subcategory only)

Regulated 0.075 1.331

Copper Forming Regulated 0.4 Production Based2

Sanitary Waste Dilution 0.05 N/A

1. Alternate Mass/Production based limits 53.3 mg/m2 for preparation and 1.68 mg/m2 for coating

2. Production based limits = 0.943 mg/off-kg of copper heat treated for solution heat treatment

MP&M General Metals Subcategory

Allowable Zn Mass = 0.38 mg/L × 100,000 gal/day × 3.785 L/gal = 143,830 mg/day
15.0 - Permitting Guidance

15-12

Porcelain Enameling

Example average daily production: 5,570 m2 of preparation

7,250 m2 of coating

Allowable Zn Mass = (53.3 mg/m2 × 5,570 m2/day) + (1.68 mg/m2 × 7,250 m2/day) = 

309,061 mg/day

Copper Forming

Example average daily production: 30,000 off-kg of copper heat treated per day

Allowable Zn Mass = 0.943 mg/off-kg × 30,000 off-kg/day = 28,290 mg/day

Combined Wastestream Formula Zinc Discharge Limit: 143,830 + 309,061 + 28,290 = 481,181

mg/day (1.06 lbs/day)

As with direct dischargers, in circumstances when the standards for one category

regulate a different set of pollutants than the standards applicable to another category, the control

authority must ensure that the stream that does not contain the regulated pollutant does not dilute

the stream containing the regulated pollutant to the point where the pollutant is not analytically

detectable. If this occurs, federal regulations at 40 CFR Part 403.6(e)(2) and (4) authorize the

control authority to establish internal monitoring points.

15.2.3 Production-Based Limits for the Steel Forming and Finishing Subcategory

As mentioned previously, EPA is proposing production-based limits for facilities

in the Steel Forming and Finishing subcategory. These facilities manufacture steel products with

uniform shapes (wire, rod, bar, pipe or tube) and currently track the weight of product produced. 

Wastewater generating manufacturing operations in the Steel Forming and Finishing subcategory

include but are not limited to acid pickling, alkaline cleaning, continuous annealing,

electroplating, hot dip coating, pressure deformation, lubrication, mechanical descaling and

painting. EPA developed the proposed production-based limits listed in Section 14 by following

the three steps below:

Step 1. Determine the technology based concentration limits for each pollutant proposed for

regulation. EPA transferred the BPT/BAT concentration-based limits from the General Metals

subcategory for all pollutants proposed for regulation. 

Step 2. Determine the PNF for each unit operation. EPA determined the amount of water used

per ton of product produced (the production-normalized flow) for each steel forming and

finishing operation performed at steel forming and finishing facilities. EPA determined the PNFs

for each steel forming and finishing operation by taking the median of the PNFs reported by steel

forming and finishing facilities in EPA’s Iron and Steel detailed questionnaire. The following
15.0 - Permitting Guidance

15-13

definitions of steel forming and finishing operations indicate the wastewater flows that EPA

included in each of the PNF determinations. 

C Acid pickling means the removal of scale and/or oxide from steel surfaces

using acid solutions. The mass-based limitations for acid pickling

operations include wastewater flow volumes from acid treatment with and

without chromium, acid pickling neutralization, annealing, alkaline

cleaning, electrolytic sodium sulfate descaling, and salt bath descaling.

C Alkaline cleaning means the application of solutions containing caustic

soda, soda ash, alkaline silicates, or alkaline phosphates to a metal surface

primarily for removing mineral deposits, animal fats, and oils. The massbased limitations for alkaline cleaning operations include wastewater flow

volumes from alkaline cleaning for oil removal, alkaline treatment without

cyanide, aqueous degreasing, annealing, and electrolytic cleaning

operations. 

C Cold forming means operations conducted on unheated steel for purposes

of imparting desired mechanical properties and surface qualities (density,

smoothness) to the steel. The mass-based limitations for cold forming

operations are based on zero wastewater discharge from welding

operations. 

C Continuous Annealing means a heat treatment process in which steel is

exposed to an elevated temperature in a controlled atmosphere for an

extended period of time and then cooled. The mass-based limitations for

continuous annealing operations include wastewater flow volumes from

heat treating operations.

C Electroplating means the application of metal coatings including, but not

limited to, chromium, copper, nickel, tin, zinc, and combinations thereof,

on steel products using an electro-chemical process. The mass-based

limitations for electroplating operations includes wastewater flow volumes

from acid pickling, annealing, alkaline cleaning, electroplating without

chromium or cyanide, and electroless plating operations.

C Hot Dip Coating means the coating of pre-cleaned steel parts by

immersion in a molten metal bath. The mass-based limitations for hot dip

coating operations includes wastewater flow volumes from acid pickling,

annealing, alkaline cleaning, chemical conversion coating without

chromium, chromate conversion coating, galvanizing, and hot dip coating

operations.
15.0 - Permitting Guidance

15-14

C Lubrication means the process of applying a substance to the surface of

the steel in order to reduce friction or corrosion. The mass-based

limitations for lubrication operations includes wastewater flow volumes

from corrosion preventive coating operations as defined in 438.61(b). 

C Mechanical Descaling means the process of removing scale by

mechanical or physical means from the surface of steel. The mass-based

limitations for mechanical descaling operations includes wastewater flow

volumes from abrasive blasting, burnishing, grinding, impact deformation,

machining, and testing operations. 

C Painting means applying an organic coating to a steel bar, rod, wire, pipe,

or tube. The mass-based limitations for painting operations includes

wastewater flow volumes from spray or brush painting and immersion

painting.

C Pressure Deformation means applying force (other than impact force) to

permanently deform or shape a steel bar, rod, wire, pipe, or tube. The

mass-based limitations for pressure deformation operations includes

wastewater flow volumes from forging operations and extrusion

operations. 

The following table lists the PNFs that EPA used in determining the production based limits for

this subcategory.

Steel Forming and Finishing Manufacturing Operation PNF (gallons/ton)

Acid Pickling 500

Alkaline Cleaning 500

Cold forming 0

Continuous Annealing 25

Electroplating 1,000

Hot Dip Coating 145

Pressure Deformation 25

Lubrication 12

Mechanical Descaling 2

Painting 65
15.0 - Permitting Guidance

15-15

Limit

Xmg

L

Ygal

short ton

L lb

gal mg

short ton

lb

XY

lb

lb

XY

kg

kkg

pn = × ×

×

×

×

×

= =

8 3454

10 2 1000

0 00000417

1000

0 00000417

6

.

.

.

conversion factor

L

gal

lb

mg

L gal

mg lb = ××

= ×

−

3 7854

453593 103 8 3454 10 6

.

.

.

Step 3. Multiply the concentration-based limit for each regulated pollutant by the appropriate

PNF from the table above and apply the conversion factor calculated below to determine the

production based limit (lbs/1,000 pounds produced).

Where X (mg/L) is the Steel Forming and Finishing subcategory concentration and Y is the

appropriate PNF (gallon/ton).

The production-based limits that EPA calculated for the Steel Forming and Finishing subcategory

using the three steps above, are listed in Section 14. In order to develop a production-based

limit for a Steel Forming and Finishing subcategory facility, the permit writer or control authority

uses the Steel Forming and Finishing limits established by EPA and listed in Section 14 and

carries out the following two steps:

Step 4. Determine a reasonable production rate in lbs/day for each of the steel forming and

finishing manufacturing operations (see Section 15.2.6 - Estimating Reasonable Production

Rates).

Step 5. For each steel forming and finishing manufacturing operation and for each pollutant

proposed for regulation, multiply the production based limit (lbs of pollutant/1,000 pounds of

product produced) by the production rate (lbs of product/day) to obtain the allowable pollutant

discharge (lbs pollutant/day). 

15.2.4 Use of Site-Specific Historical Flow Data to Calculate Flow-Based Mass

Limitations

Although EPA is not proposing to require permit writers and control authorities to convert the

proposed concentration-based limits to mass-based limits, EPA does provide the authority to do

so in the proposed rule. In cases where the permit writer or control authority is going to develop

mass-based limitations for a site with sufficient pollution prevention and water conservation

practices in place, the Agency recommends that the permit writer or control authority use the

site’s historical process wastewater flow information. Cases may also exist where a facility that

incorporates pollution prevention and water conservation practices may request that their permit
15.0 - Permitting Guidance

15-16

limits be mass-based. EPA believes that the use of historical flow to develop the limits is

appropriate in these cases as well. The use of historical flow data that reflects pollution

prevention and water conservation practices at a site reduces the opportunity for sites to dilute

their flow to achieve concentration limits. This approach also encourages sites to evaluate

existing and potential pollution prevention and water conservation opportunities.

Historical flow should be calculated as a reasonable estimate of the actual longterm discharge flow rate from a site for sites with sufficient P2 and water conservation practices. 

To develop a site-specific historical flow rate, permit writers and control authorities should

review the site’s pollution prevention and water conservation practices as well as long-term

records of the site’s flow on a monthly basis (e.g., over a 5 year period). Then, to determine the

site’s flow-based mass-limits, the permit writer/control authority multiplies the flow rate by the

concentration limit for each pollutant. 

Several documents published by the EPA’s Office of Wastewater Enforcement

and Compliance, Washington, DC, provide guidance for determining the appropriate process

wastewater flow rate (26).

15.2.5 Use of General MP&M Industry Flow Data to Develop Flow-Based Mass

Limitations

When sites do not have pollution prevention and water conservation practices in

place, the Agency recommends that the permit writer use methods other than historical flow and

production data to calculate mass-based limitations. One of these methods uses an estimate of

the flow reduction, as a percentage of the current flow, if the site implements pollution

prevention and water conservation practices. The other method uses unit-operation-specific

PNFs to calculate a maximum combined MP&M flow rate for the entire site. The PNF is the

amount of wastewater generated per unit of product manufactured, rebuilt, or repaired and is

measured as either gallons per square foot of metal surface area or gallons per ton of metal

processed. If the facility’s PNF in subsequent operational years remains at or below the PNF that

the permit writer or control authority determined to reflect good water use practices, then the

facility is likely not diluting to achieve the new MP&M limits. 

In order to determine the flow-based mass limits, the permit writer/control

authority would multiply a PNF, representative of good water use practices, times an appropriate

measure of production (i.e., square feet processed) to get a flow rate. Then, to determine the

site’s flow-based mass-limits, the permit writer/control authority multiplies the flow rate by the

concentration limit for each pollutant.

The data and information contained throughout this section should assist permit

writers and control authorities in establishing the flow reductions achieved by pollution

prevention practices and in establishing PNFs for MP&M unit operations that reflect good water

use practices. 
15.0 - Permitting Guidance

15-17

Pollution Prevention and Water Conservation Practices

EPA observed a number of pollution prevention and water conservation practices

during site visits and sampling episodes and MP&M surveys provided additional information on

these practices. Some of the common pollution prevention and water conservation methods for

surface treatment include drag-out tanks, countercurrent rinsing, manual and automatic

rinsewater shut-off, timed rinses, flow restrictors, conductivity meters, and in-process ion

exchange and water recycle. The table below shows the estimated number of MP&M facilities

currently using one or more of these techniques to limit flow.

Estimated Number of MP&M Facilities Using Various Pollution Prevention and Water

Conservation Practices to Limit Flow

Flow Control Practice Number of MP&M Facilities1

Two-stage countercurrent rinsing 1,429

Three-stage countercurrent rinsing 745

Manual rinsewater shut-off 2,464

Automatic rinsewater shut-off 426

Timed rinses 777

Flow restrictors 1,581

Conductivity meters 317

Ion exchange and water recycle 347

1Estimates of the number of MP&M facilities using the listed flow control practices are based on the 1996

MP&M Detailed Surveys, which represents 4,300 sites. The 1989 survey did not collect this information.

To assist permit writers in estimating if flows from an MP&M facility are

excessive or not when the facility does not use pollution prevention and water conservation

practices, EPA analyzed flow and production data for various rinse schemes. First, EPA

determined the most commonly used rinsing operations from the MP&M detailed surveys. Next,

using the flow and production data from each site, EPA calculated PNFs for each rinsing

operation. The table below shows the seven most common rinse types reported in the MP&M

detailed survey, along with the calculated median PNFs for each rinse type. 
15.0 - Permitting Guidance

15-18

Seven Most Common Rinse Types Reported by MP&M Facilities and Median PNFs

Rinse Type Median PNF (gal/ft2) Number of Observations

Two-stage overflow 5.0 2,332

One-stage overflow 2.0 12,867

Spray rinse 1.43 2,563

Drag-out plus one-stage overflow 1.25 1,179

Two-stage countercurrent 1.02 5,761

Three-stage countercurrent 0.44 1,045

Drag-out 0.16 2,156

Source: MP&M 1996 Detailed Surveys.

The data shown in the table above indicate that the most commonly used rinse

types are one-stage overflow and two-stage countercurrent. As discussed in Section 9.0, EPA’s

proposed technologies include two-stage countercurrent rinses as part of the water conservation

practices.

Using the median PNFs, EPA calculated the reduction in flow (percent) expected

if a facility changed from poor water use rinse types with high PNFs to a two-stage

countercurrent rinse type. Applying the percent flow reduction, the permit writer or control

authority can estimate the flow rate from the rinsing operation if the facility changed to a twostage countercurrent rinse (median PNF is 1.02). The table below shows the expected flow

reductions for changing from various rinse types to a two-stage countercurrent rinse type. 

Flow Reduction Expected After Changing From Various Rinse Types to 

Two-Stage Countercurrent

Rinse Type Expected Flow Reduction

Two-stage overflow 79.5 %

One-stage overflow 48.8 %

Spray rinse 28.4 %

Drag-out plus one-stage overflow 18.1 %

Source: MP&M 1996 Detailed Surveys.

Unit Operation PNFs

Permit writers or control authorities can use the PNFs provided in this section as

an indicator of water use practices. Table 15-1 presents descriptive statistics for PNFs obtained

from the MP&M surveys. For most unit operations, EPA based the PNFs on surface area as the

production-normalizing parameter (Table 15-1(a)). For five operations (abrasive jet machining,
15.0 - Permitting Guidance

15-19

electrical discharge machining, grinding, machining, and plasma arc cutting), the mass of metal

removed is the production-normalizing parameter (Table 15-1(b)). 

Table 15-1 presents the following information for each of the MP&M unit

operations:

C Total occurrences in the MP&M survey data (i.e., the number of times the 

unit operation was reported, regardless of whether flow and production

data were available to calculate PNFs); 

C Number of source occurrences for which flow and production data were

available to calculate PNFs;

C Minimum PNF reported;

C Maximum PNF reported;

C Median PNF reported;

C Mean PNF reported;

C Upper and lower quartile PNF reported; and

C Tenth and ninetieth percentile PNF reported.

The sites that responded to the MP&M surveys have implemented pollution

prevention and water conservation practices to varying degrees. Some sites exhibited poor water

use practices, while other sites effectively implemented one or more pollution prevention or

water conservation practices. As a result, the PNFs in Table 15-1 vary widely, by several orders

of magnitude or more in some cases. These results are not surprising, given the drastic effects of

pollution prevention and water conservation practices on reducing flow. For example,

implementing one practice, such as converting a two-stage overflow rinse to a two-stage

countercurrent rinse, can reduce water use by almost 80 percent. Differences in manufactured

parts or processing requirements also affect PNFs. 

15.2.6 Estimating Reasonable Production Rates

As discussed above, the permit writers or control authorities can use PNFs to

calculate flow rates for developing mass-based limits. The PNF can be multiplied by a

reasonable production rate (in square feet or pounds of metal removed per day, pounds of product

produced per day, etc.) through each unit operation to estimate a flow rate for that unit operation. 

In the proposed rule, particularly in reference to the Steel Forming and Finishing productionbased limits, the Agency is considering four alternatives (A through D) for determining

reasonable production rates. Each alternative requires only unit operations that generate or
15.0 - Permitting Guidance

15-20

discharge process wastewater be included in the calculation of production rates. Each of these

alternatives is discussed below. In the proposal, EPA is soliciting comment on each alternative

for determining reasonable production rates.

Alternative A: This alternative retains the essential requirements of the rule that

EPA currently regulates Steel Forming and Finishing facilities under (40 CFR Part 420.04). The

alternative requires the permit writer or control authority to use the following protocols:

C For similar, multiple production lines with process waters treated in the

same wastewater treatment system, production can be determined from the

combined production of the similar production lines during the same time

period.

C For process wastewater treatment systems where wastewater from two or

more different production lines are commingled in the same wastewater

treatment system, production shall be determined separately for each

production line (or combination of similar production lines) during the

same time period. 

This method also avoids calculating unrealistically high production estimates by only considering

production from all production units that could occur simultaneously. 

Alternative B: The Agency is considering including in the rule a requirement for

the permit writer/control authority to establish multi-tiered limits and pretreatment standards. 

Permit writers and control authorities currently use their best professional judgment for

establishing multi-tiered permits. The Agency has issued guidance for use in considering multitiered permits (see Chapter 5 of the “U.S. EPA NPDES Permit Writers’ Manual,” (EPA-833-8-

96-003, December 1996) and Chapter 7 of the “Industrial User Permitting Guidance Manual,”

(EPA 833/R-89-001, September 29, 1989)). 

In situations where a single set of effluent limitations or standards are not

appropriate for the permit’s (or control mechanism’s) entire period, a tiered permit/control

mechanism may be established. One set of limits would apply for periods of average production

along with other sets which take effect when there are significant changes in the average

production rate. The guidance notes that a 10 to 15 percent deviation above or below the longterm average production rate is within the range of normal variability. Predictable changes in the

long-term production higher than this range would warrant consideration of a tiered or multitiered permit/control mechanism. Based on EPA’s limited data, the facilities in the Steel

Forming and Finishing subcategory may have a variable production rate where the permit/control

mechanism modification process is not fast enough to respond to the need for higher or lower

equivalent limits. 

Alternative C: To provide a basis for deriving a permit/control mechanism

production rate that is consistent with the term reasonable measure of actual production and that
15.0 - Permitting Guidance

15-21

can be applied consistently for facilities in the Steel Forming and Finishing subcategory, EPA is

also considering including a definition of “production” specific to this subcategory. The

modified definition for use in developing the permit/control mechanism production basis would

be the average daily operating rate for the year with the highest annual production over the past

five years, taking into account the annual hours of operation of the production unit and the

typical operating schedule of the production unit, as illustrated by the following example:

Highest annual production from previous five years

Operating hours

Hourly operating rate

Average daily operating rate (24 hour day)

3,570,000

8,400

425

10,200

tons

hours

tons/hour

tons/day

The above example is for a unit process that is operated typically 24 hours per day

with short-term outages for maintenance on a weekly or monthly basis. For facilities in the Steel

Forming and Finishing subcategory that are operated typically less than 24 hours per day, the

average daily operating rate must be determined based on the typical operating schedule (e.g., 8

hours per day for a facility operated one 8-hour turn (or shift) per day; 16 hours per day for a

facility operated for two 8-hour turns per day). For example:

Highest annual production from previous five years

Operating hours

Hourly operating rate

Average daily operating rate (16 hour day)

980,000 

4,160 

235.6

3,769 

tons

hours

tons/hour

tons/day

In this example, EPA recognizes that the approach could cause problems for a facility that was

operated 16 hours/day at the time the permit was issued and then wished to change to 24

hours/day based on unforseen changes in market conditions. To address this issue, the approach

could be combined with the tiered permit approach discussed above. 

For multiple similar process units discharging to the same wastewater treatment

system with one compliance point (e.g., two electroplating lines operated with one treatment

system for process waters), the year with the highest annual production over the previous five

years under Alternative C would be determined on the basis of the sum of annual production for

both electroplating lines. Then, based on this year’s average daily operating rate, the daily

production rates would be calculated as above independently for each electroplating line using

total annual production and annual operating hours for each line. The daily production values

would be summed to calculate the average daily operating rate for the combination of the two

lines. For example, consider the following production data: 
15.0 - Permitting Guidance

15-22

Year

Electroplating Line A

(tons)

Electroplating Line B

(tons)

Total

(tons)

1995 1,859,000 1,305,000 3,155,000

1996 1,675,000 1,425,000 3,100,000

1997 1,760,000 1,406,000 3,166,000

1998 1,580,000 1,328,000 2,908,000

1999 1,825,000 1,380,000 3,205,000

Annual maximum production rates for each electroplating line and the

combination of the two lines are underlined. In this example, 1999 was the maximum production

year for the combination of the electroplating lines and the data from each line that year would be

used to calculate the average daily operating rates. Had the 1995 data from Electroplating Line A

and the 1996 data from Electroplating Line B been used in combination (3,275,000 tons), an

unrealistic measure of actual production might have resulted if the two electroplating lines could

not produce at these high levels concurrently.

In contrast to the previous example, for multiple process units that are not similar,

but have process wastewater commingled prior to treatment in one central wastewater treatment

system with one compliance point, the year with the highest production over the previous five

years would be determined separately for each production unit (or combination of similar and

different production units) with the highest annual production. For example, consider a situation

where process wastewater for an electroplating line, a pressure deformation operation, and an

acid pickling operation are discharged through one compliance point. Consider the following

example:

Year

Electroplating

(tons)

Pressure Deformation 

(tons) 

Acid Pickling

(tons)

1995 575,000 650,000 900,000

1996 650,000 700,000 1,000,000

1997 675,000 850,000 950,000

1998 750,000 825,000 1,125,000

1999 700,000 600,000 900,000

In this example, 1998 production data for the electroplating line, 1997 data from

the pressure deformation operation, and 1998 data for the acid pickling operation would be used

to develop the effluent limitations or pretreatment standards used in the permit/control

mechanism. 
15.0 - Permitting Guidance

15-23

Alternative D: The Agency is considering establishing production-based

maximum monthly average effluent limitations and standards in combination with dailymaximum concentration-based effluent limitations and standards. Under this alternative, the

maximum monthly average NPDES permit and pretreatment control mechanism mass basis

requirements would be determined using Steel Forming and Finishing production-based

standards listed in Section 14 in combination with a reasonable measure of actual production,

such as Alternative C above. However, the daily-maximum requirements would be in the form

of effluent concentrations in lieu of the daily-maximum production-based mass effluent

limitations guidelines and standards. These daily maximum concentrations set out as effluent

limitations guidelines and standards would be based on the long-term averages and variability

factors derived from EPA sampling conducted post-proposal at steel forming and finishing

facilities representative of BAT. 

The Agency believes this approach would effectively address the potential issue

cited above regarding short-term peaks in production under most circumstances. There would be

no additional burden on the industry and permitting or control authorities for applying for and

writing NPDES permits or pretreatment control mechanisms. Permitting and control authorities

may need to revise their automated compliance tracking systems to account for both mass and

concentration limitations at the same outfall, which is a common feature in many NPDES

permits and pretreatment control mechanisms issued prior to this proposal.

When using the appropriate production data and PNFs for conversion of

concentration-based limits to mass-based limits, the permit writer or control authority can select

an appropriate PNF from Table 15-1 for each unit operation on site. EPA recognizes that in

certain subcategories, production by unit operation may not be available (e.g., surface area

electroplated for parts that are not standard shapes like door knobs). The Agency also recognizes

that different part configurations and processing requirements may result in differing water use

requirements, even for multiple occurrences of the same operation at a site. For example, a site

manufacturing aerospace components may require a higher PNF for rinsing internal electronic

components after electroplating than for rinsing outer casings after electroplating. Because of

this diversity, while encouraging the use of lower PNFs, the Agency has provided a distribution

of PNFs for each unit operation so that permit writers and control authorities can use a siteappropriate PNF. 

While variations in water flow per unit of production result from variations in the

part configurations and processing requirements, on-site observations indicate that they are more

frequently the result of imprecise or inadequate control of water use. The permitting authority

should be aware of additional factors influencing PNFs, and the impact of these factors on the

appropriate PNF for an operation at a site. Sections 15.3 through 15.5 provide additional

guidance on determining the appropriate PNFs for the major MP&M wastewater-generating unit

operations.
15.0 - Permitting Guidance

15-24

15.2.7 Monitoring Flexibility

EPA is proposing several flexible monitoring alternatives to reduce burden on

MP&M facilities and permit writers/control authorities. This section discusses the monitoring

waiver for pollutants that are not present, monitoring for organic pollutants, and monitoring for

cyanide. The proposed rule also discusses several other possible monitoring alternatives that

were not proposed but are being considered for the final rule (i.e., site-specific correlation for an

organic pollutant indicator parameter, pretreatment sulfide monitoring waiver, and a pollution

prevention alternative).

Monitoring Waiver for Pollutants Not Present

In an effort to reduce monitoring burden on facilities, EPA is proposing to allow

MP&M indirect discharge facilities to apply for a waiver that would allow them to reduce their

monitoring burden. In order for a facility to receive a monitoring waiver, the facility would need

to certify in writing to the control authority (e.g., POTW) that the facility does not use, nor

generate in any way, a pollutant (or pollutants) at its site and that the pollutant (or pollutants) is

present only at background levels from intake water and without any increase in the pollutant due

to activities of the discharger. The facility would need to base this certification on sampling data

or other technical factors. For example, if a site does not use or generate cyanide on-site they

could submit a written certification and would not have to monitor for cyanide to demonstrate

compliance with the MP&M limits.

The certification would not be a waiver from the pollutant numerical limit in the

control mechanism (i.e., permit). It would only be a waiver from the monitoring requirements. 

EPA is proposing that the certification statement be submitted at the same time indirect

discharging MP&M facilities submit “periodic reports on continued compliance” as directed by

the General Pretreatment Standards (40 CFR 403.12(e)). Indirect dischargers submit such reports

twice per year (typically June and December). In addition, the certification would need to be

signed by the same individual that is authorized to sign the periodic reports as described in the

General Pretreatment Standards 403.12(l). In addition, EPA would still require the industrial

user to monitor for the specified pollutants as part of the Baseline Monitoring Report (403.12(b))

and the 90-day Compliance Report (403.12(d)). EPA believes control authorities can use the

sampling data generated from the Baseline Monitoring Report and the 90-day Compliance Report

in conjunction with technical information on the raw materials and chemical processes used at

the facility to determine whether there is sufficient reason to allow the monitoring waiver for any

of the MP&M limited pollutants. This monitoring waiver would be similar to the waiver in the

Proposed “Streamlining the General Pretreatment Regulations for Existing and New Sources of

Pollution,” 64 FR 39564; July 22, 1999 (commonly referred to as “Pretreatment Streamlining”)

and the waiver that was finalized for direct discharges in the “Amendments to Streamline the

NPDES Program Regulations: Round Two (65 FR 30886; 5/15/00).
15.0 - Permitting Guidance

15-25

Monitoring Alternatives for Organic Pollutants

To reduce the burden associated with monitoring for organic pollutants, EPA has

decided to propose three alternatives to allow for maximum flexibility while ensuring reductions

in the amount of organic pollutants discharged from MP&M facilities. In most subcategories,

EPA is proposing to require MP&M facilities within the scope of the rule to either: (1) meet a

numerical limit for the total sum of a list of specific organic pollutants called “Total Organics

parameter “ or “TOP” (similar to the TTO parameter used in the Metal Finishing effluent

guidelines); (2) meet a numerical limit for total organic carbon as an indicator parameter; or (3)

develop and certify the implementation of an organics management plan. Each of these

alternatives is discussed below.

For the first alternative, EPA is proposing an approach similar to the one used in

the Metal Finishing Effluent Guidelines (40 CFR Part 433). EPA developed the TOP list, using

the list of organic priority pollutants and other nonconventional organic pollutants that met EPA's

"pollutant of concern" criteria for this rule. Of the non-conventional organic chemicals on the

MP&M pollutant of concern list, EPA included only those that were removed in appreciable

quantities by the selected technology option (based on toxic weighted pound-equivalents) in two

or more subcategories. EPA then derived a numerical limit for TOP based on the contribution of

each of the organic pollutants described in Section 7 using the data collected during sampling and

determined its limitation using the statistical methodology outlined in Section 10. Facilities will

only have to monitor for those TOP chemicals that are reasonably present. (See discussion on

monitoring waiver for pollutants not present). 

For compliance purposes, pollutants that have been given a waiver (because they

are not reasonably present) will be counted as zero in the TOP limit. For remaining pollutants,

the reported value, when above the detection limit, shall be used in the TOP calculation. When a

pollutant is reported as a “non-detect” (i.e., not found above the nominal quantitation limit), the

nominal quantitation value shall be used in the TOP calculation. (Pollutant parameters not

detected in any samples collected during the MP&M sampling program are shown in Table 7-2.)

The second alternative proposed by EPA to lessen the monitoring burden is the

use of an indicator parameter (ie., total organic carbon) to measure the presence of organic

pollutants in MP&M process wastewater. EPA chose TOC as an indicator parameter because of

its ability to measure all types of organic pollutants. EPA found TOC to be the best general

indicator parameter for measuring the sum of organic compounds in a wastestream. (See DCN

16028 in Section 6.3 of the Public Record).

Finally, EPA is proposing a third alternative to reduce monitoring burden – the

use of an organic pollutant management plan. The organic pollutant management plan would

need to specify, to the satisfaction of the permitting authority or control authority, the toxic and

non-conventional organic constituents used at the facility (not only those on the TOP list); the

disposal method used; the procedures in place for ensuring that organic pollutants do not

routinely spill or leak into the wastewater or that minimize the amount of organic pollutants used
15.0 - Permitting Guidance

15-26

in the process; the procedures in place to manage the oxidation reduction potential (ORP) during

cyanide destruction to control the formation of chlorinated organic byproducts; and the

procedures to prevent the over dosage of dithiocarbamates when treating chelated wastewater. 

Facilities choosing to develop an organic pollutant management plan would need to certify that

the procedures described in the plan are being implemented at the facility. 

Monitoring Alternatives for Cyanide

For the General Metals, Metal Finishing Job Shop, Printed Wiring Board, and

Steel Forming and Finishing subcategories, EPA is proposing to set a total cyanide limit. The

point of compliance would be based on monitoring for total cyanide directly after cyanide

treatment, before combining the cyanide treated effluent with other wastestreams. EPA is also

proposing an alternative where a facility may take samples of final effluent, in order to meet the

total cyanide limit, if the permitting/control authority adjusts the limit based on the dilution ratio

of the cyanide wastestream flow to the effluent flow. 

In addition, EPA has selected alkaline chlorination using sodium hypochlorite as

the best available economically achievable technology for treating cyanide bearing wastewater

from MP&M facilities. Not all cyanide however is amenable to alkaline chlorination due to

“unavoidable” complexing with other compounds at the process source of the cyanide-bearing

wastestreams. EPA believes that for some facilities it may be more accurate to monitor for the

portion of cyanide in their wastewater that is amenable to alkaline chlorination than to measure

total cyanide which may include cyanide complexes that this technology is not likely to treat. 

Therefore, EPA is also proposing an alternative “amenable cyanide” limit for each of these

subcategories which a facility may use directly after cyanide treatment (e.g., before combining

the cyanide treated effluent with other wastestreams). 

The Agency proposes to allow the use of the amenable cyanide limit upon the

agreement of the facility and its permit writer or control authority (e.g., POTW). However, when

segregated cyanide treatment is in place as a preliminary step prior to commingling wastewater

for chemical precipitation, EPA is proposing to allow the amenable cyanide alternative limit to

be measured at the end-of-pipe (i.e., final effluent) if the control authority adjusts the permit

limits based on the dilution ratio of the cyanide wastestream flow to the effluent flow. 

If facilities are not using cyanide destruction treatment on cyanide-bearing

wastestreams prior to commingling with metal-bearing streams, additional complexing can

occur. This additional complexing would render the cyanide “non-amenable” when it would

otherwise be amenable to alkaline chlorination. EPA considers such complexing to be

“avoidable”and would not allow the use of end-of-pipe monitoring for amenable cyanide when

in-process cyanide destruction is not performed.
15.0 - Permitting Guidance

15-27

15.3 Flow Guidance for Surface Treatment Rinsing Operations

Surface treatment rinses include those following acid and alkaline treatment,

anodizing, electroplating, electroless plating, and chemical conversion coating. Rinsing dilutes

and removes the chemical film of drag-out remaining on parts and racks after processing in a

chemical bath. This subsection presents guidance for selecting the appropriate flow rate from

surface treatment rinsing operations for sites that do not have pollution prevention and water

conservation practices in place. EPA based the guidance on MP&M survey data, site visits, and

technical literature on various factors that impact rinse-water requirements, such as drag-out rates

and the required cleanliness or quality of rinse water.

Section 15.3.1 provides background information to identify pollution prevention

and water conservation practices applicable to surface treatment rinsing operations and

evaluation criteria to assess if a particular site has properly implemented these practices. Section

15.3.2 shows the influences on flow rates from surface treatment rinsing operations. Section

15.3.3 presents guidance for PNF selection.

15.3.1 Identification of Sites With Pollution Prevention and Water Conservation 

Practices

As discussed in Section 15.1, the Agency recommends that permit writers or

control authorities use historical flow data to calculate mass-based limitations, when needed, for

sites that have implemented pollution prevention and water conservation practices. This

subsection provides background information and guidance that the permit writer or control

authority can use to determine if a site has implemented pollution prevention and water

conservation practices. If the site has implemented these types of practices, the permit writer can

multiply the site’s historical process wastewater discharge flow rate by the subcategory-specific

concentration-based limitations to calculate mass-based limitations. This eliminates having to

identify alternate methods to develop mass-based limitations, including tracking production rates

through unit operations.

Many MP&M sites use some form of water conservation. Some sites implement

numerous water conservation methods and technologies in combination that result in very low

rinsewater discharge rates and in some cases eliminate the discharge of rinse water from

individual processes. Water conservation is applicable to every flowing rinse; however, processrelated factors and site-specific conditions may restrict the use of certain methods. This

subsection identifies pollution prevention and water conservation practices and technologies

applicable to surface finishing rinses, presents example configurations of these practices and

technologies at MP&M sites, and provides guidance on how to evaluate a site’s water use

practices. 
15.0 - Permitting Guidance

15-28

Pollution Prevention and Water Conservation Practices for Surface

Treatment

The Agency identified four categories of pollution prevention and water

conservation practices and technologies that can be applied to reduce rinse-water use: drag-out

reduction and/or drag-out recovery methods; improved rinse tank design and innovative rinsing

configurations; rinse-water use control devices; and, metal recovery and rinse-water reuse

technologies. In addition to conserving water use, some of these methods (especially those that

affect drag-out and recover chemicals) also conserve raw materials and reduce treatment reagent

requirements and sludge production. Within each of these categories are several specific

practices and technologies. Table 15-2 presents examples of these practices and technologies, as

well as their applicability to the MP&M unit operations. Table 15-3 provides definitions of these

practices. 

Drag-Out Reduction and Drag-Out Recovery. The quantity of water needed

for good rinsing for a given system is proportional to the quantity of drag-out from a process

bath. Sites can implement various methods that minimize the rate of drag-out (measured as

gallons per square foot of part surface area) and/or they can implement direct drag-out recovery. 

The drag-out rate for an individual process operation (e.g., cleaning or plating) depends on

numerous factors, including process type, shape of parts processed, production equipment, and

processing procedures, which include human factors. Of these factors, the shape of the parts and

the type of device used to move the parts (e.g., racks, baskets, barrels) usually have the greatest

influence on drag-out rates. The following tables present drag-out rate estimates for various

shaped parts. 

Estimates of Drag-Out Generation Presented in Literature

Average Drag-Out Losses - from Soderberg’s Work

Nature of Work Drainage Drag-Out Rate (gal/1,000 ft2)

VERTICAL

Well drained 0.4

Poorly drained 2.0

Very poorly drained 4.0

HORIZONTAL

Well drained 0.8

Very poorly drained 10.0

CUP SHAPES

Well drained 8.0

Very poorly drained 24.0

Source: Reference 1.
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Average Drag-Out Losses - from Hogaboom’s Work

Electroplating Solution Type

Drag-Out Rate (gal/1,000 ft2)

Flat Surfaces Contoured Surfaces

Brass 0.95 3.3

Cadmium 1.00 3.1

Chromium (33 oz/gal) 1.18 3.0

Chromium (53 oz/gal) a4.53 11.9

Copper cyanide 0.91 3.2

Watts nickel 1.00 3.8

Silver 1.20 3.2

Stannate tin 0.83 1.6

Acid zinc 1.30 3.5

Cyanide zinc 1.20 3.8

Source: Reference 1.

a

Increased viscosity, caused by an increase in concentration, can increase the drag-out volume approximately three

times with less than double the concentration increase.

Soderberg’s data indicate that the shape of the part has a significant influence on

drag-out rate. Cup-shaped parts, including intricately designed parts with internal surfaces, can

generate five or more times the drag-out than flat surfaced parts with the same surface area. 

Hogaboom’s data show a similar trend for flat versus contoured surfaces. These data also show

that the type and concentration of the electroplating solution influence the drag-out rate. For

example, some solutions, such as stannate tin, drain effectively, while others, such as

concentrated chromium electroplating solutions (53 oz/gal) drain poorly. As to the type of

device used to move parts, barrels (used to hold fasteners or other small parts that cannot be

practically held by racks) generate more drag-out than racks, because of the surface area of the

barrel and its tendency to hold the solution.

The drag-out rate for a given process and part is influenced by several factors

other than shape, some of which are interrelated. Table 15-4 lists these and other key factors and

describes their impact on drag-out rates. Also listed are examples of water conservation practices

that reduce the generation of drag-out, and the major restrictions that are associated with these

practices. The following table shows the effect of altering the withdrawal rate and drain time.
15.0 - Permitting Guidance

15-30

Effect of Withdrawal Rate and Drain Time on Drag-out Ratea

Micro-Etch Results

Withdrawal

Rate (ft/min)

Time of

Withdrawal

(seconds)

Drain Time

(seconds)

Total

Time

(seconds)

Drag-out

(gal/1,000 ft2)

Baseline 100 1.7 3.4 5.1 3.13

Slower rate of withdrawal 11 14.9 2.5 17.4 1.73

Intermediate withdrawal

rate and longer drain time

40 4.3 12.1 16.4 1.83

Electroless Copper

Results

Withdrawal

Rate

(ft/min)

Time of

Withdrawal

(seconds)

Drain

Time

(seconds)

Total

Time

(seconds)

Drag-out

(gal/1,000 ft2)

Baseline 94 1.8 5.2 7.0 1.55

Slower Rate of Withdrawal 12 13.9 3.2 17 0.78

Intermediate Withdrawal

Rate and Longer Drain

Time

40 4.3 11.9 16.3 0.75

Source: Reference 1.

aThe effects of changing the withdrawal rate and drain time were measured at a printed circuit board manufacturing

site. 

The following is a list of drag-out reduction practices that can be implemented on

electroplating or surface finishing lines:

C Lower process solution viscosity and/or surface tension by lowering

chemical concentration, increasing bath temperature, or using wetting

agents; 

C Reduce drag-out volume by modifying rack/barrel design and perform rack

maintenance to avoid solution trapping;

C Position parts on racks in a manner that avoids trapping solution;

C Reduce speed of rack/barrel withdraw from process solution an/or increase

dwell time over process tank;

C Rotate barrels over the process tank to improve drainage;

C Use spray/fog rinsing over the process tank (limited applicability);
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15-31

C Use drip boards and return process solution to the process tank;

C Use drag-out tanks, where applicable, and return solution to the process

tank; and

C Work with customers to ensure that part design maximizes drainage;

EPA believes that facilities must implement three or more drag-out reduction practices or use at

least one drag-out recovery technology to have good water use practices. 

Improved Rinse Tank Design and Innovative Configurations. Rinse tank

design and rinsing configuration greatly influence water usage. The key objectives for optimal

rinse tank design are to quickly remove drag-out from the part and completely disperse the dragout throughout the rinse tank. Achieving these objectives reduces the time necessary for rinsing

and minimizes the concentration of contaminants on the part when it leaves the rinse tank. 

Examples of good design include locating water inlet and discharge points of the tank at opposite

positions in the tank to avoid short-circuiting, and using air agitation for better mixing (2).

Various rinsing configurations are used in the MP&M industry. Having singlerinse tanks following each process tank is the most inefficient use of rinse water. Multiple-rinse

tanks connected in series (i.e., countercurrent cascade rinse) reduces the water needs of a given

rinsing operation by one or more orders of magnitude. Spray rinsing can also reduce water use

requirements, but the achievable percent reduction is usually less than for countercurrent cascade

rinses. Other configurations that reduce water use include cascade, reactive, and dual purpose

rinses.

Rinsewater Use Control. Regardless of the type of rinsing configuration they

use, facilities can reduce their water use by coordinating water use and water use requirements. 

Matching water use to water use requirements can optimize the quantity of rinse water used for a

given work load and tank arrangement (2). Not controlling water use negates the benefits of

using multiple rinse tanks or other water conservation practices and increases water usage. 

EPA believes that facilities should implement at least one effective method of

water use control on all electroplating or surface finishing lines. Effective water use controls

include, but are not limited to:

C Use of softened or deionized water for rinsing;

C Flow restrictors (flow restrictors as a stand-alone method of rinse water

control are only effective with plating lines that have constant production

rates, such as automatic plating machines. For other operations, there

must also be a mechanism or procedure for stopping water flow during

idle periods.);
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15-32

C Conductivity controls;

C Timer rinse controls; and

C Production-activated controls (e.g., spray systems activated when a rack or

barrel enters/exits a rinse station).

Metal Recovery and Rinsewater Reuse Technologies. MP&M sites use various

technologies to recover metals drag-out and rinses and reuse the rinsewater. The technologies

most commonly used to do this are evaporation, ion exchange, electrolytic recovery (also referred

to as electrowining), reverse osmosis, and electrodialysis (see Table 15-3 for definitions). The

following table presents examples of metal recovery technologies and the drag-out/rinses to

which they are primarily applied.

Examples of Metal Recovery Methods

Chemistry or Process

with Which Rinse is Associated Recovery Technology

Brass electroplating Electrolytic recovery, evaporation

Cadmium (cyanide) electroplating Electrodialysis, electrolytic recovery, evaporation, ion exchange,

reverse osmosis

Cadmium (noncyanide) electroplating Electrodialysis, electrolytic recovery, evaporation, ion exchange,

reverse osmosis

Chromate conversion coating of

aluminum

Evaporation

Chromium (hard) anodizing Evaporation, mist eliminator

Chromium electroplating - decorative

(Cr+6)

Evaporation

Chromium electroplating - decorative

(Cr+3)

Evaporation

Copper (cyanide and sulfate)

electroplating

Electrolytic recovery, evaporation, ion exchange, reverse osmosis

Gold electroplating Electrolytic recovery, ion exchange

Lead-tin electroplating Evaporation, ion exchange

Nickel electroplating Electrodialysis, electrolytic recovery, evaporation, ion exchange,

reverse osmosis

Nickel electroless plating Evaporation, ion exchange

Nickel sealant Reverse osmosis

Silver electroplating Electrolytic recovery, evaporation, ion exchange

Zinc (cyanide) electroplating Electrolytic recovery, evaporation, reverse osmosis

Zinc (non-cyanide) electroplating Electrolytic recovery, evaporation, ion exchange, reverse osmosis
15.0 - Permitting Guidance

Chemistry or Process

with Which Rinse is Associated Recovery Technology

15-33

Zincate Evaporation

Source: Reference 2.

Summary of Water Conservation Methods. Figures 15-2(a) through (f) present

six examples of rinsing configurations with increasingly good levels of water use practices. Each

of these rinse systems is described below. These configurations can be operated to provide

adequate rinsing and are common at MP&M sites. However, the quantity of water needed to

meet the same rinsing criteria may vary by as much as two orders of magnitude from the lowest

level to the best level of water use. The proposed MP&M effluent limitations guidelines and

standards are based on flow control and countercurrent cascade rinses for all flowing rinses.

Figure 15-2a is an example of inefficient water use. This configuration uses a

single-rinse tank with either continuous water flow or manual use control. To coordinate

rinsewater needs and use, the operator must manually turn on the water valve to give the correct

flow rate and then turn it off when the flow is no longer needed. The flow-rate setting will

usually vary by operator and the water valve may be left open during idle production periods. 

The single rinse tank configuration uses rinsewater at a very high rate, even if water use is

coordinated with the introduction of drag-out. In the example shown, with a 1-gallon-per-hour

(gph) drag-out rate, the rinsewater requirement is 30 gallons per minute, based on rinsing of

Watts nickel plating solution and a rinsing criterion of 50 mg/L nickel. If water use and drag-out

introduction are not coordinated, an even higher rinsewater use rate would be needed to meet a

given rinse criterion.

Figure 15-2b shows a rinsing configuration where simple rinsewater reduction

methods have been implemented. The water use is still inefficient because a single rinse tank is

used versus multiple rinse tanks. However, with this configuration, the drag-out rate is reduced

by controlling the withdrawal rate of the part and by holding the part over the process tank to

permit the drag-out to drip into the tank. The rinsewater flow rate is controlled at a constant flow

by a flow restrictor. The flow restrictor is usually sized to provide adequate rinsing at all times,

and is more acceptable for constant production rates, such as those often found with automated

plating machines. However, this configuration is inefficient when the work is intermittent

because the rinsewater flow rate must be set high enough to provide adequate rinsing during peak

production periods. In addition, a large quantity of rinsewater is wasted during low or idle

production periods, unless the water flow is manually stopped. 

Figure 15-2c shows a rinsing configuration using multiple rinse tanks, which

provides a moderately efficient use of water. This configuration is referred to as parallel rinsing,

where each of the two rinse tanks are fed with fresh water and they each discharge to treatment. 

This arrangement can reduce water use to less than 50 percent of that used in Figure 15-2a.
15.0 - Permitting Guidance

15-34

Figure 15-2d shows a more efficient rinsing configuration. This configuration is

similar to that shown in Figure 15-2c, except that wastewater from the second rinse tank flows

back into the first rinse tank to provide more efficient rinsing with less water use. Wastewater

from the first rinse tank is then discharged to treatment. In this configuration, known as

countercurrent cascade rinsing, the rinsewater flows in a direction opposite to the part flow. This

arrangement can reduce water use by more than 90 percent over the rinse configuration in

Figure 15-2a.

Figure 15-2e shows a very efficient rinsing configuration. There are three key

elements to this rinse system: drag-out reduction/recovery; countercurrent cascade rinsing; and

water-use control. This configuration reduces/recovers drag-out by controlling the withdrawal

rate and dwell time and by installing a drag-out recovery tank. This tank can reduce the drag-out

entering the countercurrent cascade rinses by up to 90 percent, depending on the surface

evaporation rate of the process tank. A conductivity controller controls the feed to the

countercurrent cascade rinses. This type of device coordinates water use with drag-out

introduction and reduces the influence of human error found with manually controlled rinses. An

alternative device is a timer rinse control, which is as effective as a conductivity controller when

there is no variability in drag-out volume between rinsing events.

Figure 15-2f shows a rinse system that uses an ion exchange/electrolytic recovery

unit as a chemical recovery and water recycling technology. This rinsing configuration can

reduce water use by more than 99 percent compared to the rinse configuration in Figure 15-2a,

since wastewater is discharged only from the regeneration cycle of the ion-exchange unit.

Evaluating Rinse Water Use at a Site. To identify sites with pollution

prevention and water conservation practices in place for rinsing operations, a permit writer or

control authority should determine if a facility has implemented three or more of the elements of

good rinse system design listed below on all electroplating or surface finishing lines:

C Select the minimum size tank in which the parts can be rinsed and use the

same size for the entire plating line, where practical;

C Locate the water inlet and discharge points of the tank at opposite

positions in the tank to avoid short-circuiting or use a flow distributor to

feed the rinse water evenly;

C Use air agitation, mechanical mixing, or other means of turbulence;

C Use spray/fog rinsing (less effective with hidden surfaces);

C Use multiple rinse tanks in a counter-flow configuration (i.e., countercurrent cascade rinsing); and
15.0 - Permitting Guidance

15-35

Hand

Valve

Fresh Water

Work Flow

5 sec. withdraw rate

5 sec. dwell time

Plating

Tank

Rinse

Tank

Figure 15-2a. Single Rinse Tank

Hand

Valve

Fresh Water

Work Flow

15 sec. withdraw rate

15 sec. dwell time

Plating

Tank

Rinse

Tank

Flow

Restrictor

Figure 15-2b. Single Rinse Tank with Flow Reduction

C Reuse rinse water multiple times in different rinse tanks for succeeding

less critical rinsing.
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15-36

Fresh Water

Work Flow

15 sec. withdraw rate

15 sec. dwell time

Plating

Tank

Rinse

Tank

Hand

Valve

Fresh Water

Rinse

Tank

Flow

Restrictor

Figure 15-2c. Multiple Rinse Tanks with Flow Reduction

Work Flow

15 sec. withdraw rate

15 sec. dwell time

Plating

Tank

Rinse

Tank

Hand

Valve

Fresh Water

Rinse

Tank

Flow

Restrictor

Figure 15-2d. Countercurrent Rinsing with Flow Reduction
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15-37

Work Flow 15 sec. withdraw rate

15 sec. dwell time

Plating

Tank

Rinse

Tank

Fresh Water

Rinse

Tank

Conductivity

Controller

Drag-Out

Tank

Recovered Rinse

Figure 15-2e. Multiple Rinse Tanks with Flow Reduction and Drag-Out Recovery

15 sec. withdraw rate Work Flow

15 sec. dwell time

Plating

Tank

Recycle

Rinse

Tank

Drag-Out

Tank

Recovered Rinse

C

ation C

olmn

Anion column

To treatment

Electrowinning

Unit

Scrap metal

to recycle

Metal depleted

electrolyte reused

for regeneration Regenerants

Figure 15-2f. Multiple Rinse Tanks with Water Recycle, 

Drag-Out Recovery, and Metal Recovery
15.0 - Permitting Guidance

15-38

Table 15-2 presents examples of additional practices and technologies that sites

can implement to satisfy these criteria. Although most sites that implement these practices will

conserve moderate to large amount of water, it is possible that excess water will still be used. If

a permit writer or control authority suspects that excessive water is being used, they can verify

this assumption by measuring the cleanliness or quality of the rinse water in the final rinse tanks

by using a conductivity meter or by performing an analysis of total dissolved solids (TDS). See

Section 15.3.2 for a listing of normal ranges of TDS for adequate rinsing. If the conductivity or

TDS of a given rinse is lower than that of an industry-accepted criterion, then the facility may be

using excessive water. 

15.3.2 Influences on Flow Rates

Available data show that rinsewater-use rates are related to production when

measured in terms of the surface area of parts processed. Other factors that influence rinsewater

use rates include the drag-out rate (gallons per 1,000 square feet of workload), the rinsewater

purity criteria (mg/L TDS or conductivity), the concentration of TDS in the bath (mg/L TDS),

rinse tank design and configuration (e.g., single overflow rinse versus countercurrent cascade

rinse), and the type of rinsewater flow control (e.g., manual versus conductivity controlled). 

Section 15.3.1 discusses drag-out rinse tank design and configuration, and rinsewater flow

control. The other factors are discussed below.

Rinsewater Purity Criteria. Rinsewater purity criteria are the levels of tolerable

contamination in the rinsewater. These levels vary for different processes and types of products. 

For example, rinsewater used after cleaning typically does not have to be as pure as rinsewater

used following plating, since rinsewater that remains on the plated part (essentially the drag-out

from the rinse tank) will leave spots after it evaporates if the concentration of dissolved solids in

the rinsewater is too high. Although preliminary and intermediate processing steps such as

cleaning and etching usually do not require as pure a rinsewater as final rinsing, the rinse water

needs to be pure enough to stop chemical reactions (e.g., etching) and prevent the contamination

of subsequent process solutions. Among plating processes, differences also exist in rinsewater

quality requirements. Parts plated for engineering or functional purposes (e.g., corrosion

resistance) can often be rinsed in water that is significantly less pure than decoratively plated

parts rinses.

High-purity water is needed for various rinsing operations. In some cases (e.g.,

electronics parts rinsing), tap water is not pure enough to serve as rinsewater. Before use as

rinsewater for this type of operation, the source water is purified by reverse osmosis and/or ion

exchange to remove dissolved solids and other constituents. Source water is sometimes treated

even for common rinsing operations, especially when the water supply is high in dissolved solids.

The metal finishing industry has had rinsewater quality requirements for decades. 

They are typically expressed in mg/L of TDS or in conductivity or resistivity units (resistivity is

the inverse of conductivity). The following table summarizes some generalized rinse criteria

found in the literature (1).
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15-39

Generalized Rinse Criteria

Type of Rinse

Normal Range for Adequate Rinsing

(mg/L TDS)

Alkaline Treatment/Acid Treatment Rinse 400 to 1,000

Functional or Engineering Plating Rinse 100 to 700

Decorative or Bright Plating Rinse 5 to 40

Source: Reference 1.

Permit writers or control authorities can use these criteria as a tool to assess water use practices at

a given site.

Bath Concentration. The concentration of a bath (which can be expressed in g/L

TDS) will affect the quantity of water needed for good rinsing. Baths that are more concentrated

(i.e., higher TDS) will require more rinsewater to meet the same rinsewater purity criteria as a

less concentrated bath. The bath concentration depends on the type of bath. For example, a

typical acid zinc electroplating bath will have a TDS concentration of 166 g/L and a typical

copper cyanide electroplating bath will have a TDS concentration of 250 g/L (3,4). For equal

volumes of drag-out from these two baths, the copper cyanide rinse flow must be 1.5 times

greater to achieve the same rinse quality criteria (i.e., 250/166 = 1.5). This calculation does not

account for the differences in viscosity that will also affect the volume of drag-out. For example,

for flat surfaces, the drag-out rate for a 396-g/L chromic acid bath is 3.8 times greater than that of

a 247-g/L bath (3,4). In some cases, the TDS concentration of the bath inadvertently increases

due to a buildup of bath contaminants (e.g., iron may accumulate in a chromic acid bath due to

the attack of the base metal). The TDS added by the contaminants may affect the drag-out rate in

the same manner as its intended bath constituents (e.g., chromic acid). Therefore, operating a

bath at the lowest concentration necessary to perform the job properly and maintaining bath

contaminants at low levels is a significant pollution prevention measure. 

15.3.3 Guidance for PNF Selection

The PNF has a significant impact on the maximum allowable process water flow. 

Due to the number of product/process variables that influence the PNF, permit writers or control

authorities may select different PNFs for different sites, or different PNFs for different

occurrences of the same operation within a site. The purpose of this section is to present

available data and information to support the permit writer or control authority in determining an

appropriate water-conserving PNF for an operation. The data sources are the MP&M surveys,

technical literature, and the MP&M sampling program.

Most sites should be able to achieve PNFs at the lower end of the ranges

presented in Table 15-1 when countercurrent cascade rinsing is implemented. Sites that are

unable to implement countercurrent cascade rinsing (e.g., due to space limitations in a plating

line) can usually reduce their water use by implementing other flow reduction techniques (e.g.,
15.0 - Permitting Guidance

15-40

ion-exchange recycling for electroplating rinses, flow restrictors combined with conductivity

meters for other rinses). EPA included water-conserving practices in evaluating the cost impacts

of regulation for sites affected by the proposed MP&M effluent guidelines. Section 11 discusses

estimated compliance costs. 

Certain specific conditions may affect a site’s ability to reduce its water use. The

drag-out rate may be higher than average or the rinsewater purity criteria may be lower than

average. Guidance for identifying such conditions is presented below.

A conservative estimate of an average drag-out rate is 3.2 gallons/1,000 square

feet of surface area (1). Higher drag-out rates may require greater rinsewater flows to achieve

good rinsing. An accurate method of drag-out measurement is to track the concentration of a

metal ion (or other sufficiently concentrated ion) in the rinse tank through a rinsing event. The

facility can use the rise in concentration of the ion in the rinse tank to calculate the volume of

process fluid introduced during the rinse if the concentration of that ion in the process fluid is

known.

For example, a sample of a copper sulfate process bath is collected and analyzed

for copper concentration along with two rinse samples--one before and one after a rinsing event. 

The drag-out volume for the rinsing event is: 

D ' (15-3)

Cafter & Cbefore

C

p

× Vr

where,

Cafter = Concentration of selected metal ion in rinse tank after

rinsing event (g/L)

Cbefore = Concentration of selected metal ion in rinse tank before

rinsing event (g/L)

Cp = Concentration of selected metal ion in the process tank

(g/L)

Vr = Volume of rinse tank in liters (L); and

D = Volume of drag-out in liters (L).

Several data points should be collected. Once a drag-out rate per unit area is

derived, the PNF for the rinse system is: 

PNF ' (15-4) (P / D)

Cr(ave)

× Cp(ave)

where,

P = Production rate (ft2);

D = Drag-out rate (L);
15.0 - Permitting Guidance

15-41

Cr(ave) = Average target metal ion concentration in rinse tank (g/L);

Cp(ave) = Average target metal ion concentration in process tank (g/L); and

PNF = Production-normalized flow (L/ft2).

Drag-out also can be measured using only a conductivity meter, by observing the

effect that a controlled amount of process fluid has on the conductivity of a unit volume of

rinsewater, and then applying these data to an actual rinsing event. 

For example, the conductivity of one liter of fresh rinsewater should be measured,

then again after adding and thoroughly mixing 1 milliliter of process fluid. The difference

between the two measurements should be noted. Then the conductivity of a rinse tank should be

measured prior to and after a rinsing event. The flow through the rinse tank must be closed

during the test. The drag-out volume, in liters, for the rack or barrel and parts that were rinsed is:

D ' (15-5)

Cafter & Cbefore

Cmix & Cr

× Vr

where,

Cafter = Conductivity in rinse tank after rinsing event;

Cbefore = Conductivity in rinse tank before rinsing event;

Cmix = Conductivity in mixture of 1 ml of process fluid and 1 liter of fresh

rinsewater;

Cr = Conductivity of fresh rinsewater;

Vr = Volume of rinse tank (L); and

D = drag-out rate in liters (L).

Several data points should be collected.

Rinsewater purity criteria vary for different processes. Average purity criteria for

rinsing following cleaning, functional surface finishing, and decorative surface finishing are

700 mg/L, 400 mg/L, and 22.5 mg/L, respectively. If a site indicates that their surface finishing

process requires purer rinsewater, then the permit writer or control authority may choose to use

additional resources to select an appropriate flow rate. Often, the permit writer or control

authority can identify sites that require purer rinsewater due to their use of softened or deionized

water for rinsing. They may test a site’s rinsewater to help assess their actual requirements, with

the premise that their required water purity criteria is no lower than the existing purity level in

the rinse tanks. Testing would involve collecting composite samples from the final rinse tank

following each unit operation and analyzing them for TDS.

The following are additional resources that the permit writer or control authority

can use to select an appropriate flow rate when the drag-out rate is higher than average or purer

rinsewater is necessary. 
15.0 - Permitting Guidance

15-42

Technical Literature. One source of data to use in identifying an appropriate

flow rate for an operation is technical literature. Using the rinse water purity criteria along with

the drag-out rates and the typical concentrations of TDS in various process baths, the permit

writer or control authority can calculate a “literature” flow rate. Table 15-5 presents, for several

types of rinses, calculated flow rates for a single-stage overflow rinsing configuration and a twostage countercurrent cascade rinsing configuration. Both rinsing configurations are assumed to

have flow control (i.e., water use is coordinated with drag-out introduction using a conductivity

control or other device). This table presents the TDS concentration in the associated bath (from

literature), the target TDS in the rinse (based on the rinsing criteria), the part type, the assumed

drag-out rate, and two PNF values.

 

The first value, PNF 100% Control, is a calculated value based on the assumption

that a site perfectly coordinates work flow and rinsewater use (e.g., using a conductivity

controller). In actual operations, perfect coordination is nearly impossible to achieve because the

quantity of rinsewater needed to meet a given rinse criterion usually cannot be added exactly at

the time that drag-out enters and is dispersed in the rinse tank. For example, when a barrel of

parts is rinsed, it is usually placed in a rinse tank for 1 to 3 minutes. The rinsewater volume

needed to meet the rinse criterion may be 50 gallons or more. The flow rate of water into the

rinse tank is typically less than 10 gpm (flow rates into rinse tanks vary depending on the pipe

size and water pressure and may be reduced by a flow restrictor). Therefore, it may take 5

minutes to add the 50 gallons of rinsewater. Because of this, actual water use rates will be higher

than those presented in the column, PNF 100% Control. A reasonable assumption is that good

water flow control will result in a PNF twice that of the calculated values that assume 100%

control. These flows are shown as PNF 100% excess.

The permit writer or control authority can use the rinsing configurations, drag-out

rates, target total dissolved solid (TDS) concentrations, and equations provided in Table 15-5 to

calculate other PNFs from literature sources.

MP&M Field Sampling Data. The permit writer may also find data from the

MP&M field sampling program useful in selecting an appropriate PNF for a specific operation. 

For samples collected for this program, the Agency obtained flow and production data as well as

a description of the pollution prevention and water conservation practices in place for several

sampled rinses. Table 15-6 summarizes these data, collected at two MP&M sites, for

countercurrent cascade rinsing operations (the recommended technology on which the MP&M

technology options were based). This table also shows the type of process solution, the type of

part processed through the rinse, an adjusted TDS, and an adjusted PNF. The adjusted TDS

values are common rinsing criteria found in the literature. The adjusted PNF values were

calculated using the adjusted TDS values and the equations presented with Table 15-5. 

Therefore, the adjusted PNF values are rinsewater flow rates that would be expected for these

countercurrent cascade rinsing operations if they were to provide rinsewater quality equal to the

adjusted TDS. The purpose of presenting these values is to demonstrate the reasonableness of

the PNFs calculated based on literature values in Table 15-5. 
15.0 - Permitting Guidance

15-43

15.4 Flow Guidance for Machining Operations

Many machining operations use metal-working fluids to cool and lubricate parts

and machining tools during cutting, drilling, milling, and other machining operations. These

fluids become contaminated and begin to lose their working characteristics. If neglected, the

fluids become unusable and require treatment and disposal. Through proper care, the life span of

the fluids can be extended indefinitely. For most machining operations, prolonging metalworking fluid life reduces the cost of treatment and disposal, as well as the cost of fresh coolant.

Section 15.4.1 provides background information to identify pollution prevention

and water conservation practices applicable to machining wastewater and evaluation criteria to

assess if a particular site has properly implemented these practices. Section 15.4.2 shows the

influences on flow rates from machining operations. Section 15.4.3 presents guidance for

selecting the appropriate flow rate for sites that do not have pollution prevention and recycling

practices in place. The guidance is based on various factors that impact machining fluid

requirements, including type of machining operation, base metal machined, and type of

machining system.

15.4.1 Identification of Sites With Pollution Prevention and Water Conservation

Practices

This subsection provides background information and guidance that the permit

writer or control authority can use to determine if a site has implemented pollution prevention

and water conservation practices for their machining operations. If the site has implemented

pollution prevention and water conservation practices, the permit writer or control authority can

use the concentration-based limitations to ensure compliance. If the site has not implemented

these types of practices, the permit writer can use the information in this subsection to calculate

the flow rates for developing mass-based limits (although not required). 

Many MP&M sites use some type of pollution prevention and water conservation

practices for machining wastewaters. Some sites have implemented numerous pollution

prevention and water conservation methods and technologies that result in very low machining

wastewater discharge rates and in some cases eliminate the discharge of machining fluids. 

Pollution prevention and water conservation practices are applicable to all machining operations;

however, process-related factors and site specific conditions may restrict the utility of certain

methods. 

Wastewater Generation from Machining Operations

Various types of metal-working fluids, also termed cutting fluids and coolants, are

used in machining operations to improve the life and function of machine tools. During

machining, these fluids are circulated over working surfaces, reducing friction, cooling the tool

and part, and removing metal chips from the work face. The type of fluid used depends on the

type of machining being performed and the preference of the site. The fluids are broadly divided
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into four groups: straight oil (neat oils), synthetic, semisynthetic, and soluble oil. The most

commonly used fluids are soluble oils synthetics, and semisynthetics.

Water-soluble coolants are prepared by mixing a concentrated coolant with water

in a 1:15 to 1:30 ratio to produce a fluid with a 90 to 98 percent water content. Most water

soluble coolants are suitable for light- and medium-duty operations. Synthetic coolants are

designed for high cooling capacity, lubricity, and corrosion prevention. Common chemical

agents in synthetics include: amines and nitrites for rust prevention; nitrates for nitrite

stabilization; phosphates and borates for water softening; soaps and wetting agents for

lubrication; phosphorus, chlorine, and sulfur compounds for chemical lubrication; glycols to act

as blending agents; and biocides to control bacteria growth. Semisynthetics contain small

dispersions of oil in an almost otherwise organic water-dilutable system. Straight oils are good

lubricants, but are less effective for cooling, and therefore are limited mostly to use in low-speed

operations (8).

Metal-working fluids are periodically discarded because of reduced performance

or development of a rancid odor. The fluids that contain a large percentage of oil typically are

hauled as solid waste for disposal or recovery. Fluids with lower oil content typically are sent to

a site’s wastewater treatment system for treatment and subsequent discharge. 

Metal-working fluids degrade mainly because of contamination with tramp oil and

dirt and by bacterial growth, which can be accelerated by tramp oil contamination. Tramp oil

contamination is caused mostly by oil from the part’s surface during machining and by leaks of

lubricating and hydraulic oils from the machine. Airborne dust or poor housekeeping practices

can cause dirt to accumulate. Bacteria are initially contributed from the surfaces of the machine

and parts and from the air. More than 2,000 known species of bacteria have been reported to

affect and eventually destroy the stability of machining fluids (5). Bacteria feed on the fluids’

chemicals, causing the fluids to lose lubricity and corrosion inhibition. Under anaerobic

conditions, sometimes caused by floating tramp oil in coolant sumps, bacteria generate a

hydrogen sulfide odor.

In addition to spent fluid, machining operations may generate wastewater from

rinsing. Machined parts may be rinsed to remove fluid, chips and other foreign materials. 

However, parts typically are not rinsed following machining. More frequently, the fluid is

permitted to remain on the part to inhibit corrosion, is wiped off using shop towels, or is cleaned

in an alkaline cleaning or degreasing operation.

The quantity of wastewater generated by a machining operation depends primarily

on the volume of work performed. Production volume can be roughly measured by the quantity

of metal stock removed by turning, milling, boring, broaching, cutting and other machining

operations. For most machining operations, the removed metal consists of small fragments

called chips or fines. Most chips carry a thin film of fluid on their surfaces, which, when it

drains, is another source of wastewater.
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Pollution Prevention and Water Conservation Practices for Machining

Operations

The Agency has identified two categories of pollution prevention and water

conservation practices and technologies that can be applied to reduce metal-working fluid

discharge: those used to prevent metal-working fluid contamination and those used to extend the

life of machining fluids, including recovering and recycling metal-working fluids. Within each

of these categories are several specific practices and technologies. Table 15-7 presents several

examples of these practices, which are discussed below.

Prevention of Metal-Working Fluid Contamination. Sites can implement

various methods to reduce the amount of fluid contamination. Several of these methods are

discussed below.

Reduction of Contamination From Tramp Oil. Tramp oil is a primary

contaminant in machining fluids and for many sites the major cause of metal-working fluid

degradation. The Agency has identified the following methods to reduce contamination of metalworking fluid with tramp oil.

C Use of Coolant in Hydraulic and Other Oil Systems. Some metal-working

coolants are formulated to be used as hydraulic fluid and/or lubricant in

concentrated form, and as a coolant in its dilute form (i.e., diluted with

water). When used as a hydraulic fluid or lubricant, leaks of the fluid will

be assimilated into the coolant without causing contamination.

C Replacement of Hydraulics with Electrical Systems. Hydraulic systems on

some machines can be replaced by newer electrical systems that do not

contain hydraulic fluid. This replacement could be economically

performed during major equipment overhauls.

C Machine Maintenance. Machine design and age may affect the quantity of

hydraulic oil that leaks to the metal-working fluid during machining

operations. There are numerous hydraulic systems used with machines,

depending on the type of machine. These systems will leak variable

quantities of oil depending on design, sealing mechanisms, operating

pressures, and other factors. Older machines, especially those that are not

properly maintained, can have excessive leaking from hydraulic seals. 

Sites should implement scheduled maintenance of machines to check and

repair sealing mechanisms.

Reduction of Contamination from Makeup Water. Makeup water contributes to

the dissolved solids content of the metal-working fluid, reducing fluid life. This problem occurs

more rapidly when water with high TDS is used for evaporative makeup. Certain dissolved

solids or minerals cause more problems for metal-working fluids than others. For example,
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chloride salts and sulfates corrode at levels of greater than 100 parts per million. Sulfates also

promote the growth of sulfate-reducing bacteria that cause fluids to become rancid. When

minerals become concentrated in the fluid, they can cause increased corrosion, gumming, and

machine wear (8). Consequently, using hard water can reduce the fluid life. Deionized (DI)

water can be used in place of hard water (DI units can be either purchased or rented).

Reduction of Contamination from Sumps. The Agency has identified the

following methods to reduce contamination from metal-working fluid sumps:

C Steam Cleaning of Sumps. Machine coolant sumps harbor bacteria that

degrade the fluids. If coolant sumps are not sterilized during clean-outs,

the fresh coolant added to cleaned sumps may be degraded by residual

bacteria. Bacteria from sumps can be eliminated by steam cleaning during

clean-out.

C Sump Modification. Many coolant sumps are designed as in-ground

concrete tanks, whose porous concrete surfaces absorb oil and promote

bacterial growth. Fluid life may be extended by improving the design of

the sumps. Potential design changes include inserting metal tanks and

coating sump walls with fiberglass or other non porous material. 

Reduce Miscellaneous Contamination. Good housekeeping practices can extend

metal-working fluid life by reducing contamination. Sites can implement housekeeping

procedures to keep floor sweepings, solvents, paint chips, soil, rags, paper, and other debris out

of the coolant sumps.

Extension of Metal-Working Fluid Life. Sites can implement several methods

to extend the life of metal-working fluids. These include raw material substitution, equipment

modification, and fluid monitoring, as discussed below.

Raw Material Substitution. As discussed above, four general types of metalworking fluids are used in machining operations. Within a given group of fluids, such as soluble

oil, various formulations are used. Within each group, the major difference from one fluid to

another is the “additive package.” Additives are included in most metal-working fluid

formulations to improve fluid performance (e.g., improve lubricity, reduce friction, or increase

corrosion protection) and increase life span (e.g., reduce bacterial growth). Costs of different

metal-working fluids can vary by 100% or more. Fluids with additive packages that do not meet

the lubrication and cooling requirements of the specific machining operation may degrade faster

than other metal-working fluids. These fluids will need to be replaced more often and increase

overall operating costs. These fluids may also affect tool life, further increasing operating costs. 

Therefore, using the proper grade metal-working fluids can increase the life span of the fluid,

reducing the generation of waste machining fluids and decreasing the overall operating costs.
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Equipment Modification. The Agency has identified the following types of

equipment modifications that can extend the life of machining fluids.

C Replacement of Air Agitation With Mechanical Agitation. Some sites use

air agitation in central coolant sumps to constantly mix the fluid and

prevent phase separation and pooling of tramp oil. However, air agitation

increases the activity of aerobic bacteria by adding oxygen, which causes

the bacteria to consume fluid additives. An alternative method of mixing

is mechanical agitation (i.e., pumping). Mechanical agitation mixes

without increasing the oxygen concentration of the coolant.

C Removal of Tramp Oil. Machining fluid life can be extended by

continuous, in-sump removal of tramp oil. Sites can install continuous oilskimming devices directly in the machine sump to remove tramp oil. 

Tramp oil can also be removed using absorbent blankets, fabrics, or

pillows.

Fluid Monitoring. During use, the metal-working fluid undergoes various

physical, chemical, and biological changes. If the properties of the fluid are monitored on a

regular basis, the fluid can be adjusted before it is degraded. Parameters measured to monitor the

fluid include: pH, coolant concentration (using a refractometer or titration kit), TDS, tramp oil

(visual) and biological activity (using dip slides available from coolant suppliers and laboratories

(3) or other methods). These data can be used to guide periodic fluid adjustments and/or develop

statistical process control (SPC) procedures. Fluid concentration should be monitored at least

weekly, if not daily. The correct pH operating range of most coolants is 8.5 to 9.5. If the pH

drops below the operating range, coolants may cause rusting and be prone to increased biological

activity. Dilute concentrations can shorten tool life, increase biological activity, and cause rust. 

Rich concentrations can lead to foaming and tramp oil contributes to biological growth.

Metal-Working Fluid Recycling. Most metal-working fluids can be recycled on

site by removing contaminants accumulated during use and storage. Recycling methods include

settling, straining, skimming, simple filtration, membrane filtration, coalescing, centrifugation,

cyclone separation, magnetic separation, and pasteurization. Some of these methods can be used

in combination to recover nearly 100% of the metal-working fluid. Sites can purchase recycling

equipment or hire commercial services that perform on-site processing (6,7,23). A self-contained

recycling unit can be purchased that is specifically designed for smaller machine shops and is a

complete sump maintenance and fluid recycling system in one unit (8). In most cases, sites can

facilitate metal-working fluid recycling by consolidating the types of machining fluids they use to

one or two types of fluid.

Additional metal-working fluid can be recycled by chip drainage. Chip drainage

can account for up to 50 percent of annual fluid use (7). During machining, the metal chips

(scraps) become coated with fluid. Part of the fluid drains from the chips and part remains on the

chips. In many cases, the chips and associated fluid are dropped to the floor and manually
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collected in storage containers. Some machines send the chips and fluid to a storage container

using automated equipment (e.g., belt or pneumatic conveyor). Fluid that drains from chips can

be recycled rather than discharged, which may require design changes of chip handling and 

storage equipment. 

Evaluating Metal-Working Fluid Use at a Site

To identify sites with pollution prevention and water conservation practices in

place for machining operations, the permit writer or control authority should focus on the

categories of practices discussed above. Specifically, sites should pass both of the following

criteria for the majority of machining operations on site: 

C The site should use practices and/or technologies to prevent contamination

of the metal-working fluid; and

C The site should use some type of practice or technology to extend the life

of the metal-working fluid.

Table 15-7 presents examples of practices and technologies that sites can implement to satisfy

these criteria.

15.4.2 Influences on Flow Rates

Available data show that wastewater discharge rates from machining operations

are a function of production when measured in terms of the mass of metal stock removed by the

machining operations (see Table 15-1). Wastewater discharge rates are also affected by other

factors that cause PNFs to vary from site to site. The most important of these factors are the type

of metal-working fluid used, the design of the machine fluid system, the machining operations

performed, and the fluid management practices used. Other factors include base material being

machined, climatic conditions, design and age of machines, and chip storage methods. Sites

control several of these factors (e.g., type of metal-working fluid, fluid management practices,

and chip storage methods) by implementing pollution prevention and water conservation

practices and technologies. The other factors are, to a degree, beyond the control of the site and

will affect the minimum flow rate achievable by a site. The effects of several of these factors on

flow rates are discussed below.

Design of the Machine Fluid System. Fluids used in machining are stored either

in sumps dedicated to individual machines (either internal or external to the machine), or in

central sumps that serve multiple machines. Large machining operations typically use central

sumps, whereas small machine shops tend to have individual sumps for each machine. Central

systems usually contain three to five times greater volume of fluid per machine from individual

sumps. The reservoir volumes of most machines with internal sumps are typically 10 to 50

gallons. External sumps serving a single machine typically have a volume of 1,000 to 2,500

gallons. Central sumps may have volumes that exceed 50,000 gallons.
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The amount of make-up fluid in a central system amounts to a smaller percentage

of total fluid than in a single machine operation. Consequently, the potential for bacterial

degeneration is greater in central systems as the bacteria have a longer time in which to attack the

fluid (5). Further, central sumps are often unlined concrete basins, whose porous walls hide

bacteria and prevent complete disinfecting during clean-outs. This reduces the time needed for

the bacteria to become reestablished (7). Additionally, the larger pumps used in central systems

keep the tramp oils suspended in the fluid so they do not readily “float out,” adding to further

bacterial attack. Central systems may require more maintenance than dedicated sumps to prevent

bacterial growth.

Machining Operations Performed. The ratio of scrap metal (e.g., chips)

generated to fluid used varies among machining operations. For example, metal cutting may

generate large pieces of scrap metal using a small volume of fluid, whereas a milling operation

usually produces a much smaller mass of chips for the same volume of fluid. However, based on

the MP&M survey database, EPA did not identify any trends in PNF across types of machining

operations performed.

Base Material Being Machined. The type of base material being machined

affects the quantity of metal-working fluid used. The hardness of base materials varies, which in

turn affects the speed at which the base metal can be removed. Harder metals require more fluid

than softer metals for the same operation. 

Climatic Conditions. The temperature of the shop can affect the life span of

metal-working fluid in that warmer temperatures may foster the growth of certain bacteria.

Design and Age of Machines. The design and age of machines may affect the

quantity of hydraulic oil that is leaked to the metal-working fluid during machining operations. 

Numerous hydraulic systems are used with machines. These systems will leak variable amounts

of oil depending on design, sealing mechanisms, operating pressures, and other factors. Older

machines, especially those that are not properly maintained, can have hydraulic seals that

excessively leak.

Uniform Coolant Use. Minimizing the number of different machine coolants

used at a facility and reduces the chance of formulation errors. When employees are familiar

with fluid properties and coolant formulation chemistry, it is less likely that coolant batches will

be prepared incorrectly, which many times requires the entire batch to be discharged to the onsite wastewater treatment facility. Facilities may also save money by purchasing larger volumes

of coolant (i.e., economies of scale).

15.4.3 Guidance for PNF Selection

The following table presents PNF data (summarized from Table 15-1(b)) from the

MP&M surveys for machining operations. Data are in gallons of wastewater (i.e., primarily

spent coolant and associated rinsewater, if used) discharged per pound of metal removed.
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PNFs For Machining Operations

Minimum

PNF

10th

Percentile

25th

Percentile

Median

PNF

75th

Percentile

90th

Percentile

Maximum

PNF

Mean

PNF

0.0003 0.011 0.05 0.12 0.18 1.68 376 1.6

Source: MP&M Detailed Survey Database.

As shown in this table, the PNFs for machining operations range over several

orders of magnitude. Based on data gathered from the MP&M surveys, site visits, and technical

literature, the Agency believes that the wide range of PNFs indicates the variety and extent of

pollution prevention practices in use at MP&M sites (e.g., sites with coolant maintenance and

recycling practices in place versus sites without these practices in place).

For sites that do not have pollution prevention and recycling systems in place for

machining operations, the permit writer or control authority can use the PNF data to estimate

target flows. The permit writer can multiply the daily amount of metal (lbs) processed through

all machining operations by the median PNF (gal/lb) to determine the site’s target daily flow

(gal/day).

The Agency believes that most sites can reduce their flow rates to levels at or

below the median PNF for machining operations by implementing one or more of the pollution

prevention and water conservation practices discussed previously. Site-specific conditions may

limit the ability of certain sites to reduce their flow rates. 

15.5 Flow Guidance for Painting Operations

Paint is applied to a base material for protective and decorative reasons in various

forms, including dry power, solvent-diluted formulations, and water-borne formulations. 

Various methods of application are used, the most common being immersion and spraying. 

Water is used in painting operations in paint booth water-wash systems (water curtains), in

water-borne formulations, in electrophoretic painting solutions and rinses, and in clean-up

operations. This discussion is directed at water use in spray painting booths; however, this

subsection also provides some information on rinsing following electrophoretic painting and

water clean-up.

Section 15.5.1 presents background information to identify pollution prevention

and water conservation practices applicable to painting operations. This includes discussions of

wastewater generated from painting operations, and practices and technologies that can be

implemented to reduce wastewater discharges. Section 15.5.2 discusses influences on flow rates. 

Section 15.5 presents guidance for selecting appropriate flow rates for sites that do not have

pollution prevention and water conservation practices in place. The guidance is based on various

factors that impact water use requirements.
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15.5.1 Identification of Sites With Pollution Prevention and Water Conservation

Practices

This subsection provides background information and guidance that the permit

writer or control authority can use to determine if a site has implemented pollution prevention

and water conservation practices for painting operations. If the site has implemented pollution

prevention and water conservation practices, the permit writer or control authority can use the

concentration-based limitations to ensure compliance. If the site has not implemented pollution

prevention and water conservation practices, the permit writer or control authority can use the

information in this subsection to calculate the flow rates for developing mass-based limitations.

Wastewater Generation from Painting Operations

In spray painting, an organic coating is applied to a product. During

manufacturing operations, spray painting is usually performed in a booth to control the

introduction of contaminants and the release of solvent and paint to the work place and

environment, and to reduce the likelihood of explosions and fires. Paint booths are categorized

into two types (dry-filter or water wash) by the method of collecting the over spray (i.e., the paint

that misses the product during application). The type of booth designs selected depends mainly

on production requirements, including part size and configuration, production rate and transfer

efficiency, the material being sprayed, and finish quality requirements.

Dry-filter booths use filters to screen out the paint solids, by pulling prefiltered air

through the booth, past the spraying operation, and through the filter. The air entrains the

overspray and is pulled through the filter, which collects the paint. Solvent evaporates from the

paint, leaving the paint solids on the filter. Filters are periodically replaced when they become

laden with paint solids and the air flow through them is restricted. Dry-filter booths are most

often used when paint usage does not exceed 20 gallons/8-hour shift/10 feet of chamber width

(14). At higher usage rates, the frequency of filter changes greatly increase operating costs (i.e.,

filter, filter disposal, and labor).

The only water used with dry filter units is to clean painting equipment (e.g., guns

and lines) when water-borne paints are used. The operation of dry-filter units is essentially dry

when solvent-based paints are used.

Water-wash booths use a “water curtain” to capture paint overspray. Air

containing entrained paint overspray is pulled through a circulating water stream, which “scrubs”

the overspray from the air. There are two primary types of water-wash booths, side-draft and

downward-draft. The basic difference between the two types is the way the air moves through

the system to draw the paint overspray in for capture (15,16). Side-draft units are typically used

by small painting operations and the downward-draft units are used with large and/or continuous

operations.
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Water-wash booths use a water stream that recirculates from a sump or tank with

a typical capacity of 200 to 5,000 gallons or more. Downward-draft systems normally contain

much larger volumes of water than side-draft systems. Water is periodically added to the system

as make-up for evaporative losses. The sump water is periodically discharged, usually during

general system cleaning or maintenance. The discharge rate depends on various factors,

including booth design, paint type, overspray rate, and the water treatment methods used. Water

is also used to clean the painting equipment and the paint booth. Booth cleanup may involve

using paint stripper to remove dried paint from the walls of the booth and the piping system.

A common practice in water-wash booth operation is to immediately detacify

suspended paint solids to reduce maintenance problems and to subsequently separate and remove

the solids from the water. The organic resins that make up the bulk of the paint coating are

insoluble in water and tend to stay tacky if not treated with some other material added to the

water (15,16). If left untreated, the tacky solids can plug recirculation pipes and pumps and

adhere to wetted surfaces of the booth. Dissolved solids are either immediately precipitated and

flocculated, removed by water treatment, or discarded when the sump is discharged.

Solids can be detacified and removed in various ways, depending on the type of

paint used and the booth design. Detacification chemicals include sodium hydroxide (caustic),

metal salts, clay, and polymers. Depending on the type of paint and the detacification chemical,

the paint solids may either disperse or agglomerate. Agglomerated solids may either sink or

float. In solids dispersal, the suspended solids increase in concentration as over spray enters the

water. Subsequently, another chemical is added to the water that causes the dispersed solids to

agglomerate into a dense floc, which is then removed.

Paint solids are removed from the booth water-wash system by various means. 

These removal technologies vary in sophistication, automation, efficiency (removal and

separation), and capital and operating costs. The most common methods include passive settling,

skimming, screening, filtration (bag, roll bed, press), and centrifugal methods (hydrocyclone,

centrifuge).

Another common method of painting is electrophoretic painting (also known as

electrocoating or electrodeposition), which is the process of coating a work piece by making it

either anodic or cathodic in a bath that is generally an aqueous emulsion of the coating material. 

The electrophoretic painting bath contains stabilized resin, pigment, surfactants, and sometimes

organic solvents in water. Electrophoretic painting is used primarily for primer coats (e.g.,

bodies for motor vehicles or mobile industrial equipment) because it gives a fairly thick, highly

uniform, corrosion-resistant coating in relatively little time. During this process, precleaned parts

carrying an electrical charge are immersed into the coating tank (paint) and then through a rinsing

system. Rinsing removes excess paint (drag-out) from the parts. The typical rinsing procedure is

a three-stage countercurrent rinse, and may include both dip and spray rinsing. Typically, the

final rinse is performed with deionized water.
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Ultrafiltration is commonly used to separate and recover paint solids and recycle

rinsewater, by counter flowing the rinsewater into the painting bath and filtering the bath with

ultrafiltration. The ultrafilter removes excess water from the bath, recycles the paint solids to the

bath, and recycles the water (permeate) to the rinse system. Occasional blowdown of rinse water

is needed to purge the system of contaminants. The volume of wastewater discharged can be

reduced by processing the rinsewater through a reverse osmosis unit (17).

Pollution Prevention and Water Conservation Practices for Painting

Operations

The Agency has identified three categories of pollution prevention and water

conservation practices that sites can implement to reduce or eliminate wastewater discharges

from painting operations: practices to reduce the quantity of paint entering the water system;

recycling technologies for paint booth water; and conversion of water-wash booths to dry-filter

booths. These are discussed in this subsection and summarized in Table 15-8. 

Reducing the Quantity of Paint Entering the Water System. Sites can

implement various methods to reduce the quantity of paint entering the water system. Three of

these methods are discussed below.

Improving Spray Painting Operating Practices. Sites can implement various

practices that reduce the quantity of paint and other material entering the water system of a paint

booth and thereby reduce the need to discharge wastewater. Generally, implementing these

practices only requires operator training. These practices include: racking and positioning parts

to minimize over spray; selecting the proper nozzle for an efficient spray pattern; scheduling

work to reduce color changes and associated clean-outs of guns, lines, and pots; and

housekeeping to prevent painting wastes and foreign materials from entering the booth’s water

system.

Improving Transfer Efficiency. The transfer efficiency (i.e., spray efficiency) is

the amount of coating that is applied to the part divided by the amount of coating that is sprayed

from the gun. It is reported as a percentage. The transfer efficiency depends on several factors,

including the spraying equipment, part size and configuration, paint type, and operating methods. 

By improving the transfer efficiency, booth water processing requirements can be reduced.

During the past 15 years, spraying equipment has improved, primarily in response

to more stringent air pollution regulations and rising paint costs. One of the key improvements

has been replacement of conventional compressed air spray equipment by more efficient

equipment. In terms of transfer efficiency, the common types of spray equipment are ranked as

follows (shown in order of increasing efficiency with relative transfer efficiencies shown in

parenthesis): conventional compressed air (25%), airless (35%), air assisted airless (45%),

electrostatic, (65%), and high-volume/low-pressure (HVLP) (80%) (12). The HVLP equipment

has been widely implemented due to the high transfer efficiency, as well as the low cost of

converting from conventional compressed air equipment. The cost is primarily for the spray
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guns, since the compressors and other equipment are the same as for conventional compressed air

painting equipment.

Installing Gun Cleaning Station. After use, spray-painting equipment must be

cleaned to prevent a buildup of paint solids. Spray guns are often cleaned by spraying solvent

through the lines and guns and into the booth. However, this practice increases the amount of

paint entering the booth’s water system and increases emissions of volatile organic compounds

(VOCs). An alternative practice is to install gun-cleaning stations. A commercial gun-cleaning

unit is designed to sit on top of a 55-gallon drum. The gun is connected to the solvent tank and

the drum. Solvent is drawn through the gun and exits into the drum, where it can be recovered

by distillation (9).

Booth Water Recycle. Various methods and equipment can reduce or eliminate

the discharge of the water used in water-wash booths. These methods and equipment prevent the

continuous discharge of booth waters by conditioning (i.e., adding detacifiers and paintdispersing polymers) and removing paint solids. The least efficient paint booth water-wash

system, in terms of water use, is one where the paint solids are not conditioned and accumulate

until booth water must be replaced. Cleaning such systems typically involves draining or

pumping the water from the booth reservoir and contract hauling the entire waste product. Due

to high operating costs and downtime, this procedure is usually used only by low production

operations. With moderate- and high-production levels, daily, if not continuous, booth water

maintenance is needed to conserve water. The most basic form of water maintenance is the

removal of paint solids by manual skimming and/or raking. These solids can be removed

without water conditioning since some portion of solvent-based paints usually floats and/or

sinks. With the use of detacifiers and paint-dispersing polymer treatments, more advanced

methods of solids removal can be implemented. Some common methods are discussed below.

Wet-Vacuum Filtration. Wet-vacuum filtration units consist of an industrial wetvacuum head on a steel drum containing a filter bag. The unit vacuums paint sludge from the

booth. The solids are filtered by the bag and the water is returned to the booth. Large vacuum

units are also commercially available that can be moved from booth to booth by forklift or

permanently installed near a large booth.

Tank-Side Weir. A weir attached to the side of a side-draft booth tank allows

floating material to overflow from the booth and be pumped to a filtering tank for dewatering

(15,16).

Consolidator. A consolidator is a separate tank into which booth water is

pumped. The water is then conditioned by adding chemicals. Detacified paint floats to the

surface of the tank, where it is skimmed by a continuously moving blade. The clean water is

recycled to the booth (15,16).

Filtration. Various types of filtration units are used to remove paint solids from

booth water. The booth water is pumped to the unit where the solids are separated, and the water
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is then returned to the booth. The simplest filtration unit consists of a gravity filter bed with

paper or cloth media. Vacuum filters are also used, some of which require precoating with

diatomaceous earth (15,16).

Centrifuge Methods. Two common types of centrifugal separators are the

hydrocyclone and the centrifuge. The hydrocyclone is used to concentrate solids. The paint

booth water enters a cone-shaped unit under pressure and spins around the inside surface. The

spinning increases the gravity, which causes most of the solid particles to be pulled outward to

the walls of the cone. Treated water exits the top of the unit and the solids exit the bottom. 

Some systems have secondary filtration devices to further process the solids. The centrifuge

works in a similar manner, except that the booth water enters a spinning drum, which imparts the

centrifugal force needed to separate the water and solids. Efficient centrifugation requires close

control of the booth water chemistry to assure a uniform feed. Also, auxiliary equipment such as

booth water agitation equipment may be needed.

Conversion of Water-Wash Booths to Dry-Filter Booths. Water-wash booths

can be converted to or replaced by dry-filter booths. The dry-filter booths have the potential to

eliminate the wastewater discharge, but they create a solid wastestream. The choice between

using a water-wash booth or a dry-filter booth is primarily based on the amount of over spray. It

is usually cost-effective to use a dry-filter booth when paint usage does not exceed 20 gallons/

8-hour shift/10 feet of chamber width (14).

A 1989 U.S. Navy study concluded that conversion from wet to dry booths can be

cost-effective for a range of operations. This study included a survey of military and industrial

facilities that have successfully been converted and an economic analysis based on typical Navy

painting operational parameters (19). 

Evaluating Water Use for Painting Operations

To identify sites with good painting-related water use practices, a permit writer or

control authority should focus on the categories of these practices discussed above. Specifically,

sites should meet both of the following criteria for the majority of painting operations on site:

(1) The site should use practices and/or technologies to reduce the amount of

paint entering the water system; and

(2) The site should use some type of practice or technology that minimizes or

eliminates the discharge of wastewater by recycling the water used during

painting or replacing existing wet systems with dry systems.

Table 15-8 presents examples of practices and technologies that sites can implement to satisfy

these criteria.
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15.5.2 Influences on Flow Rates

Available data show that wastewater discharge rates from painting operations are

a function of production when measured in terms of the surface area of parts painted (see Table

15-1(a)). Wastewater discharge rates are also affected by other factors that cause PNFs to vary

from site to site. Some sites are able to operate without a wastewater discharge, while others

have a wide range of PNFs. The most important of these factors are the paint transfer efficiency,

booth type and reservoir size, maintenance requirements of the booth, the booth water chemistry

and water recycling methods used, and the chemical make-up of the paint being applied. Sites

can control a few of these factors (e.g., paint transfer efficiency and the booth water chemistry

and water recycling methods used) by implementing the proper pollution prevention and water

conservation practices and technologies. The other factors are, to a degree, beyond control of the

site and will affect the minimum PNF achievable by a site. The effects of several of these factors

on PNF are discussed below.

Solvent, Paint Solids, and Other Components of Paint. The chemical make-up

of the paint can impact the PNF. The recirculated water in a water-wash booth contains the

various constituents of the paint(s) being applied. With most solvent formulations, the solvents

(e.g., xylene, toluene, methylene chloride) are not water-soluble, but can be water-miscible. 

Some exceptions, such as acetone and methyl ethyl ketone (MEK), are water-soluble. However,

in most cases, the solvents are volatile and evaporate over time and exit the booth through the air

exhaust system. The organic resins that make up the bulk of the paint coating are insoluble in

water and tend to stay tacky if not treated with some additional material introduced to the water

(15,16). If left untreated, the tacky solids can plug recirculation pipes and pumps and adhere to

wetted surfaces of the booth. Other paint additives, such as wetting agents, pigments, and heavy

metals (e.g., zinc and chromium salts) may be soluble in water. These constituents can be made

partly insoluble and removed by adjusting the chemistry of the water.

Water-based paints present two problems with regard to water use. First, these

paints disperse in water rather than agglomerate like solvent-based paints. This makes the

maintenance of paint booth waters more difficult (15,16). Second, water is used to clean

spraying equipment when water-based paints are applied, which may generate wastewater. A

typical equipment-cleaning procedure is to flush with water, then solvent, then water (18).

Paint Booth Maintenance Requirements. Water-wash paint booths are

periodically shut down for maintenance, which usually requires that the water in the booth be

removed. Various conditions can exist that may create a need to discharge the water, including

odor, bacterial growth, foaming, TDS buildup, and the presence of corrosion and scale

constituents.

Booth maintenance typically involves incidental repairs and cleaning the booth

surfaces and piping system. Often this is performed according to a maintenance schedule, but

periodic repairs may also necessitate an unplanned shut-down and clean-out. A common cleanout procedure is to remove the accumulated paint solids from the water, transfer the water to a
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holding tank, and return the water after the maintenance has been performed. Alternate methods

are draining the booth water to a sewer or wastewater treatment system or having it hauled to a

disposal site. Systems with accumulated paint solids on the wetted surfaces of the booth and in

the piping system can be cleaned by circulating an alkaline cleaner or other chemical for

dissolving paint. Since the amount of water discharged from water-wash paint booths is a

function of the system’s maintenance requirements, newer systems that require less maintenance

will discharge less water. Therefore, one pollution prevention option for water-wash paint

booths is to install new systems or upgrade existing systems to limit maintenance requirements.

15.5.3 Guidance for PNF Selection

The following tables presents PNF data (summarized from Table 15-1) from the

MP&M surveys for spray and immersion painting operations, respectively. Data are in gallons of

wastewater (i.e., discharged paint booth waters) per square foot of surface area painted.

PNFs for Spray Painting Operations

Minimum

PNF

10th

Percentile

25th

Percentile

Median

PNF

75th

Percentile

90th

Percentile

Maximum

PNF

Mean

PNF

0.0001 0.002 0.02 0.04 0.04 0.10 1.5 0.08

Source: MP&M Detailed Surveys.

PNFs for Immersion Painting Operations

Minimum

PNF

10th

Percentile

25th

Percentile

Median

PNF

75th

Percentile

90th

Percentile

Maximum

PNF

Mean

PNF

0.00004 0.00006 0.0005 0.02 0.02 0.19 55 4.6

Source: MP&M Detailed Surveys.

As shown in these tables, the PNFs for painting operations range over several

orders of magnitude. The MP&M survey data do not include information on the exact types of

pollution prevention and water conservation practices in place at the MP&M sites; therefore, the

PNFs listed in this table cannot be directly linked to these practices. Based on data gathered

during site visits and from information in technical literature, the Agency believes that the wide

range of PNFs indicates the degree to which the sites practice pollution prevention and water

conservation (e.g., sites with paint booth water recycling practices in place versus sites without

these practices in place).

Based on the available data, the Agency believes that most sites can approach zero

discharge of painting booth wastewaters if they implement recycling. For sites that have not

implemented recycling of paint booth water, permit writers and control authorities can use the

PNF data in the tables above to estimate flow rates for developing mass-based limitations.
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15.6 Flow Guidance for Cleaning Operations

Cleaning operations include aqueous degreasing, acid treatment, alkaline

treatment, and electrolytic cleaning. Depending on the chemicals, equipment, and procedures

used, these processes are commonly referred to as immersion, spray, or electrolytic alkaline

cleaning; immersion, spray, or electrolytic acid cleaning or pickling; ultrasonic cleaning; and

emulsion cleaning and parts washing. 

This section addresses flow guidance for cleaning solutions or baths. Cleaning

solutions become contaminated during use and the constituents of the bath are depleted. When

the performance of the baths is reduced, the baths are discharged to treatment or contract hauled

for off-site treatment and disposal. Rinse waters are also generated from cleaning operations;

flow guidance aspects of rinsing are discussed in Section 15.2. 

Section 15.6.1 provides background information to identify pollution prevention

and water conservation practices applicable to cleaning operations and evaluation criteria to

assess if a particular site has properly implemented these practices. Section 15.6.2 shows the

influences on flow rates from cleaning operations. Section 15.6.3 presents guidance for PNF

selection.

15.6.1 Identification of Sites With Pollution Prevention and Water Conservation

Practices

This subsection provides background information and guidance that can be used

by the permit writer or control authority can use to determine if a site has implemented pollution

prevention and water conservation practices for their cleaning operations. If the site has

implemented pollution prevention and water conservation practices, the permit writer or control

authority can use the concentration-based limitations to ensure compliance. If the site has not

implemented pollution prevention and water conservation practices, the permit writer or control

authority can use the information in this subsection to estimate flows for developing mass-based

limitations. 

Many MP&M sites implement pollution prevention and water conservation

methods and technologies that result in low cleaning wastewater discharge rates, and in some

cases, eliminate the discharge of cleaning solutions. Pollution prevention and water conservation

practices are applicable to all cleaning operations; however, process-related factors and sitespecific conditions may restrict the utility of certain methods. This subsection identifies

pollution prevention and water conservation practices and technologies applicable to cleaning

operations and provides guidance on how to evaluate a site’s water use practices. 

Wastewater Generation From Cleaning Operations

MP&M sites commonly perform cleaning as a stand-alone operation or in

combination with other MP&M unit operations such as anodizing, electroplating, conversion
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coating, and painting. Cleaning removes surface contaminants that affect the appearance of parts

or the ability to further process the parts. Various types of acidic and alkaline solutions are used

for cleaning.

Alkaline cleaners are usually impacted by organic soils such as oil and grease. 

The effectiveness of most alkaline cleaners is reduced when the oil concentration of the bath is in

the range of 1 to 5 g/L or more. Oil and grease enter the alkaline cleaning bath on the parts being

processed. The rate of oil buildup depends on the production rate (measured in square feet per

day) and the quantity and characteristics of the contamination on the parts. Acid treatment

solutions and, to a lesser extent, alkaline treatment solutions accumulate dissolved metals from

corrosion of the base metals being processed. The dissolved metal reduces the strength of the

cleaning bath. As dissolved metal increases, additional acid or alkaline solution is added;

however, at certain metal concentrations, the bath is no longer usable. The tolerable

concentration of dissolved metals depends mostly on the type of acid or alkaline solution and the

function of the bath. The buildup rate of dissolved metal depends primarily on the production

rate, type and concentration of acid or alkaline solution, type of base metal, duration of cleaning

cycle, and bath temperature.

Pollution Prevention and Water Conservation Practices for Cleaning

Operations

The Agency identified three categories of pollution prevention and water

conservation practices that can be implemented to reduce or eliminate wastewater discharges

from cleaning operations: housekeeping and maintenance; oil and suspended solids removal; and

dissolved solids removal. These are discussed in this subsection and summarized in Table 15-9. 

Housekeeping and Maintenance. Sites can implement various housekeeping

and maintenance practices to reduce the quantity of cleaning solution discharge. Several of these

practices are discussed below.

Solution Testing. The chemical make-up of cleaning solutions changes over time

due to evaporative losses, water additions, cleaning chemical drag-out, chemical reactions, and

drag-in of impurities. Because of these factors, cleaning baths lose strength, performance

declines, and solutions require disposal. Many sites operate cleaning baths on a three-step

schedule: formulate, use, and discard. This procedure can be expensive and inefficient from a

production standpoint, and creates large volumes of waste. For this reason, sites should

frequently test the strength of the cleaning solution and appropriate chemical additions needed to

continue using the solution. By implementing testing and record keeping, sites can reduce the

disposal frequency of cleaning baths.

Most alkaline cleaning solutions are proprietary formulations, and the vendors of

these solutions provide test methods for determining the condition of a bath. Also, commercial

test kits are available that include generic test methods. For example, the strength of an alkaline

cleaning solution can be tested using acid-base titration, which measures alkalinity. Also, there
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is a dual test method that indirectly measures the level of contamination in the cleaner. This

process consists of titrating a measured sample of cleaner (e.g., 5 ml) and then adding a color

indicator (phenolphthalein or methyl orange) with an acid of precise concentration (e.g., 1N

solution of sulfuric acid). Phenolphthalein is used as the indicator to measure free alkalinity and

methyl orange is used to measure total alkalinity. By performing both tests, the ratio of total

alkalinity to free alkalinity can be calculated. A ratio close to 1 indicates that the cleaner is

relatively free of contamination, while a higher ratio indicates that contamination exists. This

ratio is sometimes used to determine if a cleaning solution should be discharged. For example, a

common guideline used is that the solution is discarded when the ratio exceeds 2.0. The total

alkalinity/free alkalinity test method does not work for all cleaners. Because of additives used,

some alkaline cleaners do not have any free alkalinity. In such cases, it is necessary to perform

more elaborate tests to accurately determine the contaminant concentration (e.g., oil and grease

measurement).

Similar test methods exist for acid cleaners. The most common parameters that

are included in acid cleaner test programs are acid concentration and dissolved metal

concentration. The concentration of sulfuric acid or hydrochloric acid in pickling solutions is

usually measured by titrating a sample of the solution with sodium carbonate and using a methyl

orange indicator. Iron and other dissolved metals can also be measured by titration or by using

laboratory analytical equipment such as an atomic adsorption spectrophotometer.

Recordkeeping. Recordkeeping is essential to maintaining all metal processing

solutions, including acid and alkaline cleaners. By maintaining accurate records, a site can

identify trends in solution use and focus on extending the lives of those that are frequently

discarded. Important records to keep are occurrences of chemical additions and solution dumps,

production throughput, and analytical data.

Miscellaneous Housekeeping and Maintenance. To obtain consistently good

cleaning results and reduce their solution discharge, sites should implement a regular schedule of

housekeeping and maintenance. Tasks should include: checking the accuracy of temperature

controls; removing sludge buildup from tanks, heating coils, and temperature regulators;

retrieving parts, racks, and other foreign materials dropped into the tanks; and checking the

integrity of tanks and tank liners.

Oil and Suspended Solids Removal. Cleaning baths accumulate oil and

suspended solids during use. These contaminants eventually reach a concentration that interferes

with the effectiveness of the cleaning process, despite the fact that most bath constituents remain

usable. Also, contaminated cleaning baths may carry over contaminants to subsequent process

solutions. As a result, cleaning baths are often discarded when they reach a certain concentration

of contaminants. There are several technologies used to remove oil and suspended solids from

cleaning solutions, thereby extending the useful life span of the solutions. These technologies

are primarily applicable to alkaline cleaning baths, and are discussed below.
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Free/Floating Oil Separation Devices. Separation devices for oil/water mixtures

use the difference in specific gravity between oils and water to remove free or floating oil from

wastewater. Common separation devices for cleaning solutions include skimming devices

(disks, belts, and rotating drum oil skimmers), and coalescers. These devices are not suited for

emulsified oil removal, which requires chemical treatment or membrane filtration.

Skimming is a simple method for separating floating oil from cleaning solutions. 

Skimming devices are typically mounted onto the side of a tank and operate on a continuous

basis. The disk skimmer is a vertically rotating disk (typically 12 to 24 inches in diameter) that is

partially submerged into the liquid of a tank (typically 4 to 12 inches below the surface). The

disk continuously revolves between spring-loaded wiper blades that are located above the

surface. The adhesive characteristics of the floating oil cause it to adhere to the disk. As the disk

surface passes through the wiper blades, the oil is removed and diverted to a run-off spout for

collection. Maximum skimming rates typically range from 2 to 10 gallons per hour of oil. Belt

and drum skimmers operate similarly, with either a continuous belt or drum rotating partially

submerged in a tank. As the surface of the belt or drum emerges from the liquid, the oil that

adheres to its surface is scraped (drum) or squeezed off (belt) and diverted to a collection vessel. 

Coalescers separate liquids with specific gravity differences of 0.09 and greater. 

Coalescers are typically tanks containing a coalescing media that accelerates phase separation

(20). A suction skimmer removes cleaning solution and oil from the process tank and pumps it

to the coalescer. The media in the coalescers is a material such as polypropylene, ceramic, or

glass that attracts oil in preference to water (i.e., oleophilic). The oil/cleaner mixture passes

through the unit and the oil adheres to the coalescing media. The oil forms droplets that

conglomerate and rise to the surface of the tank, where the oil is removed by a skimming device

or weir. According to Stoke’s Law, the rise/fall velocity of a dispersed-phase droplet is

exponentially increased with the droplet size. Therefore, the coalescing media separates the

phases more rapidly than a common gravity settling device.

Media Filtration Methods. Filtration removes suspended solids from cleaning

solutions. Common types of filters include cartridge filters, precoat diatomaceous earth filters,

and sand or multimedia filters. Cartridge filters are available with either in-tank or external

configurations; the in-tank filters typically are used for small tanks and the external filters for

larger tanks. Most cartridges are disposable; however, washable and reusable filters are

available, which further reduce waste generation. Precoat, sand, and multimedia filters are used

mostly for large tank applications. The type of filter media used is based on the chemical

composition of the bath. All filtration systems are sized based on solids loading and the required

flow rate. Typical flow rates for cleaning solution applications are two to three bath turnovers

per hour.

Membrane Filtration. Microfiltration and ultrafiltration are membrane-based

technologies used primarily to remove emulsified oil and other colloids from cleaning solutions. 

The solution entering a microfiltration or ultrafiltration unit is typically filtered conventionally to

remove large particulates. Various devices then trap or skim floating oils and allow heavier
15.0 - Permitting Guidance

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solids to settle. The solution is pumped into the membrane compartment, where the membrane

traps remaining oil and grease while water, solvent and other cleaning bath constituents pass

through. The fluid flows parallel to the membrane with enough velocity to remove the reject

from the membrane surface. Ceramic membranes are available in various pore sizes ranging

from several hundred angstroms to over 0.2 microns. The appropriate pore size is determined by

the specific cleaner to be filtered. The capacity of a unit is based on the total area and flux rate of

the membrane. Commercially available units range in capacity from less than 260 to more than

1,300 gallons per day. 

Dissolved Metals Removal. Metals become dissolved in acid and alkaline

cleaning solutions as a result of corrosion of the base metal. The dissolved metal forms salts or

other compounds that reduce the strength of the cleaning bath. Technologies used to remove

dissolved metals include acid sorption, diffusion dialysis, and membrane electrolysis, discussed

below.

Acid Sorption. Acid sorption is an acid purification technology that is applicable

to various acid treatment solutions, as well as other acidic baths (e.g., anodizing baths). The acid

sorption unit resembles an ion-exchange column. The column contains a bed of alkaline anion

exchange resin that separates the acid from the metal ions. 

First, spent acid is pumped upward through the resin; the acid is absorbed by the

resin while the metal ions pass through it. The resulting metal-rich, mildly acidic solution is

collected at the top of the bed. Water is then pumped downward through the bed and desorbs the

acid from the resin. The purified acid solution is collected at the bottom of the bed. This

technology can recover approximately 80% of the free acid remaining in a spent acid treatment

solution. Purification can be performed in a batch mode, but is most effective in a continuous

flow mode (usually expressed in terms of the mass of metal removed from the acid solution per

unit time). Equipment capacity ranges from 100 grams/hour to several thousand grams/hour. 

Units are sized to remove metal near or above the rate at which the metal is being introduced. 

Typically, a target level of metal concentration is determined and the unit is sized to maintain

that level. 

Diffusion Dialysis. Diffusion dialysis is a membrane process that separates metal

contaminants from the acid solution using an acid concentration gradient between solution

compartments. Anion exchange membranes are used to create the compartments. The

membranes are usually assembled in a membrane stack, like that used with electrodialysis. The

contaminated acid passes through one set of compartments and deionized water through the

adjacent compartments. Acid is diffused across the membrane into the deionized water whereas

metals are blocked due to their charge and the selectivity of the membrane. Unlike

electrodialysis, no electrical potential is used. The acid diffuses because of the difference in acid

concentration on either side of the membrane (i.e., material in high concentration moves to an

area of low concentration). 
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Membrane Electrolysis. Membrane electrolysis is a bath maintenance technology

that lowers or maintains the concentration of metallic impurities in cleaning solutions. This

technology is also applicable to other metal-bearing solutions (e.g., electroplating, anodizing, and

stripping solutions). This technology uses an ion-exchange membrane(s) and an electrical

potential applied across the membrane(s). The membrane is ion-permeable and selective,

permitting ions of a given electrical charge to pass through. Cation membranes allow only

cations, (e.g., copper, nickel, aluminum) to pass from one electrolyte to another, while anion

membranes allow only anions (e.g., sulfates, chromates, chlorides, cyanide) to pass through. 

Bath maintenance units can be configured with cation or anion membranes or both. 

A typical application of membrane electrolysis is maintenance of an acid cleaning

solution. The cleaning solution is placed in an anode compartment that is separated from a

second electrolyte by a cation membrane. The solution in the cathode compartment (i.e.,

catholyte) is typically a dilute acidic or alkaline solution. When an electrical potential is applied,

the dissolved metals in the cleaning solution migrate through the cation membrane, into the

catholyte. The catholyte is periodically discarded when it becomes saturated with metals.

Evaluating Cleaning Solution Use at a Site

To identify sites with good solution use practices in place for cleaning operations,

the permit writer or control authority should focus on the categories of these practices discussed

above. Specifically, sites should meet both of the following criteria for the majority of cleaning

operations on site:

(1) The site should use practices to monitor the chemical condition of cleaning

solutions and make additions/corrections, as needed; and

(2) The site should use some type of practice or technology to extend the life

of the cleaning solution, including the prevention of contamination and the

removal of contaminants.

Table 15-9 presents examples of practices and technologies that sites can implement to satisfy

these criteria.

15.6.2 Influences on Flow Rates

Available data show that wastewater discharge rates from cleaning operations are

a function of production when measured in terms of the surface area of parts processed (see

Table 15-1). Wastewater discharge rates are also affected by other factors that cause PNFs to

vary from site to site. Some sites are able to operate without a wastewater discharge, while other

sites have a wide range of PNFs. The most important of these factors are the condition of the

surfaces being cleaned, cleaning requirements, type of cleaning process used, and the methods

used for maintaining the cleaning solution in usable condition. Sites can control this last factor

by implementing the proper pollution prevention and water conservation practices and
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technologies, as discussed previously. The other factors are, to a degree, beyond control of the

site and will affect the minimum PNF achievable by a site. The affects of these factors on PNF

are discussed below.

Condition of the Surfaces Being Cleaned. The condition of the parts being

cleaned varies widely, both in terms of the types and quantities of contaminants present and the

quantity of oil. For example, some parts may have been wiped clean and have only a light

deposit of metal-working fluids, while other parts may be heavily coated. Since metal-working

fluids (oils) present on the parts are removed during the cleaning process (aqueous degreasing),

the rate of oil that is entering into the cleaning solution per square foot of part cleaned will vary. 

The type of oil entering the cleaning solution will also affect the cleaning fluid’s life-span.

Cleaning Requirements. Some processes, such as electroplating, require a high

degree of cleanliness while others, such as phosphate conversion coating, may have less stringent

requirements. The cleaning requirements will therefore vary within a site, as well as from site to

site, as will the type of cleaning process selected. 

Some cleaning processes are more amenable to pollution prevention practices than

others, based on the purpose of the cleaning process. For example, many electroplating

processes require etching of the surface of the part to enhance adhesion of the electroplated metal

deposit. Surface etching introduces dissolved metal into the cleaning solution and will reduce its

life-span.

Type of Cleaning Process and Equipment. The life-span of cleaning solutions

depends on the type of cleaning process (i.e., process chemistry and cleaning equipment). 

Numerous factors affect the selection of a cleaning process, including: type and characteristics of

contaminants to be removed; type and condition of base metal; size and configuration of parts;

degree of cleanliness required; processing capabilities at the site; subsequent operations to be

performed; and financial considerations.

The factors that most affect the selection of process chemistry and equipment are

the type of contaminants present on the parts, type of base metal, and the subsequent finishing

operation, which in turn dictates the cleaning requirements. Contaminants present on parts can

be divided into organic and inorganic contaminants. Examples of organic contaminants are

machining fluids, miscellaneous oils, waxes, and buffing compounds, which are typically

removed by solvents, detergents, and alkaline solutions. Examples of inorganic contaminants are

scale, smut, and grinding residue, and are typically removed by acidic solutions. Various

methods are used to apply the cleaning solution. For example, solutions can be applied by

spraying or immersing, and can be applied electrolytically (including both anodic and cathodic

cleaning). Application method is primarily based on the concentration and condition of the

contaminant and the configuration of the parts.

The base material of the parts is also a consideration in selecting a cleaning

process. Some base materials are chemically or physically altered by certain cleaning steps
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because of oxidation, etching, activation, and hydrogen embrittlement. Such changes may be

either desirable or damaging. The base material is also important in considering the operating

conditions of the cleaning process (e.g., concentration, temperature, current). Further, the base

material contaminates the cleaning solution (e.g., etching during acid treatment), and therefore

affects the life span of the solution.

15.6.3 Guidance for PNF Selection

The following table presents PNF data (summarized from Table 15-1) from the

MP&M surveys for cleaning operations. Data are in gallons of solution discharged per square

foot of surface area processed.

PNFs for Cleaning Operations

Unit Operation

Minimum

PNF

10th

Percentile

25th

Percentile

Median

PNF

75th

Percentile

90th

Percentile

Maximum

PNF

Mean

PNF

Aqueous Degreasing 0.0001 0.003 0.009 0.04 0.45 3.8 125 2.3

Acid Treatment 0.000001 0.001 0.004 0.009 0.03 0.2 140 0.43

Alkaline Treatment 0.00002 0.002 0.01 0.01 0.02 0.24 141 1.1

Electrolytic Cleaning 0.00001 0.0005 0.003 0.01 0.08 0.70 85 2.4

Source: MP&M Detailed Surveys.

As shown in this table, the PNFs for cleaning operations range over several orders

of magnitude. The MP&M survey data do not include exact information on the types of

pollution prevention and water conservation practices in place at the MP&M sites; therefore, the

PNFs listed in this table cannot be directly linked to these practices. Based on the data gathered

during site visits and from technical literature, the Agency believes that the wide range of PNFs

indicates of the variety of water use practices in place at MP&M sites (e.g., sites with cleaning

solution maintenance and recycling practices in place versus sites without these practices in

place).

Based on the available data and information, the Agency believes that most sites

can reduce their flow rates from cleaning operations by implementing pollution prevention and

water conservation practices. Site-specific conditions may limit the ability of certain sites to

reduce the flow rates. 
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15.7 References

1. Kushner, Joseph B. Water and Waste Control for the Plating Shop. Gardner

Publications, Inc., 1976.

2. Cushnie, George C. Pollution Prevention and Control Technology for Plating

Operations. National Center for Manufacturing Sciences, 1994.

3. Lownheim, Frederick A. Electroplating Fundamentals of Surface Finishing.

McGraw-Hill Book Co., New York, NY, 1978.

4. Murphy, Michael, Ed. Metal Finishing Guidebook and Directory Issue for 1994.

Metal Finishing Magazine, Hackensack, NJ, 1994.

5. Master Chemical Corporation. A Guide to Coolant Management.

6. Higgins, Thomas. Hazardous Waste Minimization Handbook. Lewis Publishers,

Chelsa, MI 1989.

7. Ebasco Environmental. Hazardous Waste Minimization Study, Air Force Plant

No. 6. Final Report, Norcross, GA, 1992.

8. University of Northern Iowa. Cutting Fluid Management in Small Machine Shop

Operations. Iowa Waste Reduction Center, Cedar Falls, Iowa, undated.

9. Lighthall Industries, LightahallTM SC 70 Gun Cleaner, Lighthall Industries, Santa

Cruz, CA

10. InVireChem. Service Bulletin: First Considerations in Classifying Pint Waste

from Spray Booths. InVireChem, Inc., 1989.

11. Nalco. HEC Management Services Program Total Spray Booth Management. 

Nalco Chemical Company, 1989.

12. Marg, Ken, “HVLP Spray Puts You into Compliance.” Metal Finishing, March

1989.

13. Hund, Jerry. “Spray Application Processes,” Metal Finishing Organic Finishing

Guidebook and Directory Issue for ‘94. Metal Finishing, Hackensack, NJ, May,

1994.

14. Thomas, Barry, “Spray Booths,” Metal Finishing Organic Finishing Guidebook

and Directory Issue for ‘94. Metal Finishing, Hackensack, NJ, May, 1994.
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15. Monken, Alan. “Wastewater Treatment Systems for Finishing Operations,” Metal

Finishing Organic Finishing Guidebook and Directory Issue for ‘94. Metal

Finishing, Hackensack, NJ, May, 1994.

16. Monken, Alan. “Water Pollution Control for Paint Booths,” Metal Finishing

Organic Finishing Guidebook and Directory Issue for ‘94. Metal Finishing,

Hackensack, NJ, May, 1994.

17. Brewer, George. “Electrodeposition of Organic Coatings,” Metal Finishing

Organic Finishing Guidebook and Directory Issue for ‘94. Metal Finishing,

Hackensack, NJ, May, 1994.

18. Joseph, Ron. “Low-VOC Waterborne Coatings,” Metal Finishing Organic

Finishing Guidebook and Directory Issue for ‘94. Metal Finishing, Hackensack,

NJ, May, 1994.

19. Ayer, Jacqueline and McElligott, Anthony, “Navy Paint Booth Conversion

Feasibility Study (CR 89.004),” Naval Civil Engineering Laboratory, January,

1989.

20. Batutis, Edward, F. “Keep Your Cleaners Clean,” Products Finishing, October,

1989.

21. Berg, Jack, “Filtered Thoughts--Start at the Cleaning Line,” Metal Finishing,

November, 1986.

22. Steward, F.A. and McLay, W.J. “Waste Minimization Part IV -

Recovery/Regeneration of Process Baths”, Metal Finishing, November 1985.

23. Freeman, H.M. Standard Handbook of Hazardous Waste Treatment and Disposal.

McGraw-Hill, New York, NY, 1989.

24. U.S. Environmental Protection Agency, Office of Water Regulations and

Standards. Guidance Manual For the Use of Production-Based Pretreatment

Standards and the Combined Wastestream Formula, September 1985.

25. U.S. Environmental Protection Agency, Office of Water Regulations and

Standards. Guidance Manual for Electroplating and Metal Finishing Pretreatment

Standards, EPA-440/1-84-091g, February 1984.

26. U.S. Environmental Protection Agency, Office of Water. NPDES Permit Writers’

Manual, EPA-833-B-96-003, December 1996.
15-68

15.0 - Permitting Guidance

Table 15-1 (a)

Descriptive Statistics of MP&M Survey Data for Unit Operations with Square Feet as the ProductionNormalizing Parameter

Unit Operation

Total

Occurrences

Number of 

PNF

Calculations

Minimum

PNF

(gal/ft2)

10th

PNF

Percentile

(gal/ft2)

25th

PNF

Percentile

(gal/ft2)

Median

PNF

(gal/ft2)

75th

PNF

Percentile

(gal/ft2)

90th

PNF

Percentile

(gal/ft2)

Maximum

PNF

(gal/ft2)

Mean

PNF

(gal/ft2)

Abrasive Blasting 91 28 0.0003 0.0008 0.003 0.026 1.04 1.6 3.9 0.59

Abrasive Blasting Rinse 61 43 0.009 0.26 0.69 1.3 2.4 5.4 40.3 3.1

Acid Treatment with Chromium 61 47 0.00004 0.001 0.008 0.009 0.04 0.09 2.1 0.08

Acid Treatment with Chromium

Rinse

50 48 0.002 0.12 1.0 1.3 6.7 41.7 2,686 77

Acid Treatment without

Chromium

1,724 1,569 0.000001 0.001 0.004 0.009 0.03 0.20 140 0.43

Acid Treatment without

Chromium Rinse

1,422 1,406 0.0001 0.12 0.46 1.3 3.8 19.9 2,631 16.1

Adhesive Bonding 4 4 0.002 0.008 0.02 0.03 0.26 0.65 0.91 0.24

Adhesive Bonding Rinse 0 0 NA NA NA NA NA NA NA NA

Alkaline Cleaning for Oil

Removal

567 534 0.00002 0.002 0.013 0.01 0.023 0.24 141 1.1

Alkaline Cleaning for Oil

Removal Rinse

407 401 0.0003 0.02 0.16 0.70 1.7 11.8 472 8.3

Alkaline Treatment with Cyanide 23 17 0.002 0.01 0.01 0.01 0.07 1.2 9.0 0.72

Alkaline Treatment with Cyanide

Rinse

16 16 0.4 0.4 0.74 2.9 24.2 85.7 153 25.6

Anodizing with Chromium 21 17 0.001 0.006 0.01 0.01 0.01 0.03 0.20 0.023

Anodizing with Chromium Rinse 19 19 0.04 1.1 3.9 3.9 4.3 9.0 20.9 5.0

Anodizing without Chromium 81 60 0.0002 0.004 0.01 0.01 0.01 0.04 1.44 0.06

Anodizing without Chromium

Rinse

72 71 0.017 0.27 1.2 3.9 5.0 16.7 938 19.1

Aqueous Degreasing 175 110 0.0001 0.003 0.009 0.04 0.45 3.8 125 2.3

Aqueous Degreasing Rinse 109 69 0.0006 0.016 0.075 0.4 3.8 15.3 2,945 48.3

Assembly/Disassembly 75 3 0.041 0.07 0.11 0.19 0.22 0.24 0.25 0.16
15-69

15.0 - Permitting Guidance

Table 15-1 (a) (Continued)

Unit Operation

Total

Occurrences

Number of 

PNF

Calculations

Minimum

PNF

(gal/ft2)

10th

PNF

Percentile

(gal/ft2)

25th

PNF

Percentile

(gal/ft2)

Median

PNF

(gal/ft2)

75th

PNF

Percentile

(gal/ft2)

90th

PNF

Percentile

(gal/ft2)

Maximum

PNF

(gal/ft2)

Mean

PNF

(gal/ft2)

Assembly/Disassembly Rinse 7 5 0.13 0.31 0.59 0.59 0.59 0.59 0.59 0.50

Barrel Finishing 274 44 0.0006 0.005 0.03 0.48 8.2 72 123 16.3

Barrel Finishing Rinse 103 22 0.002 0.009 0.07 1.6 2.9 5.6 81 5.7

Burnishing 21 5 0.012 0.17 0.4 0.84 2.8 39.9 64.7 13.8

Burnishing Rinse 11 1 2.07 2.07 2.07 2.07 2.07 2.07 2.07 2.07

Calibration 2 2 0.59 0.59 0.59 0.59 0.59 0.59 0.59 0.59

Chemical Conversion Coating

without Chromium

459 221 0.0000025 0.0004 0.001 0.006 0.075 0.5 96.8 0.87

Chemical Conversion Coating

Without Chromium Rinse

366 242 0.0001 0.04 0.16 0.74 2.7 7.1 648 12.9

Chemical Milling 111 79 0.0009 0.015 0.02 0.06 0.11 0.40 11.4 0.3

Chemical Milling Rinse 103 90 0.002 0.18 0.5 1.2 3.0 11.4 64.5 4.3

Chromate Conversion Coating 386 120 0.0000007 0.00006 0.0005 0.008 0.039 1.0 47.9 0.9

Chromate Conversion Coating

Rinse

229 135 0.0028 0.016 0.13 0.60 4.3 26.2 2,000 37.2

Corrosion Preventive Coating 178 71 0.00003 0.0009 0.003 0.01 0.052 0.69 42.3 1.8

Corrosion Preventive Coating

Rinse

73 61 0.0002 0.15 0.34 1.2 2.0 6.0 833 15.9

Electroless Plating 123 98 0.0002 0.001 0.003 0.02 0.09 0.8 5.9 0.34

Electroless Plating Rinse 116 103 0.005 0.17 0.64 2.2 7.3 26.1 374 17.1

Electrolytic Cleaning 146 137 0.00001 0.0005 0.003 0.013 0.08 0.70 85.7 2.4

Electrolytic Cleaning Rinse 133 132 0.0001 0.02 0.2 0.8 5.5 22.2 446 14.0

Electroplating with Chromium 73 39 0.0007 0.006 0.02 0.02 0.03 2.7 11.4 0.88

Electroplating with Chromium

Rinse

77 71 0.006 0.2 1.0 2.6 13.1 38.8 943 26.7

Electroplating with Cyanide 261 121 0.00004 0.002 0.007 0.02 0.16 0.95 90.6 1.4

Electroplating with Cyanide

Rinse

235 219 0.0003 0.04 0.57 2.6 16.6 80.0 1,828 38.4

Electroplating without Chromium

or Cyanide

522 260 0.00001 0.0004 0.005 0.02 0.075 0.5 23.5 0.45
15-70

15.0 - Permitting Guidance

Table 15-1 (a) (Continued)

Unit Operation

Total

Occurrences

Number of 

PNF

Calculations

Minimum

PNF

(gal/ft2)

10th

PNF

Percentile

(gal/ft2)

25th

PNF

Percentile

(gal/ft2)

Median

PNF

(gal/ft2)

75th

PNF

Percentile

(gal/ft2)

90th

PNF

Percentile

(gal/ft2)

Maximum

PNF

(gal/ft2)

Mean

PNF

(gal/ft2)

Electroplating without Chromium

or Cyanide Rinse

496 490 0.0003 0.12 0.60 2.6 10 42.1 9,333 54.7

Electropolishing 18 17 0.0002 0.01 0.01 0.01 0.03 3.7 7.7 0.92

Electropolishing Rinse 14 14 0.01 0.04 0.8 3.5 19.9 27.2 187 20.6

Floor Cleaning 388 340 0.00008 0.006 0.008 0.1 0.1 1.3 156 2.0

Floor Cleaning Rinse 75 73 0.0025 0.009 0.06 0.1 0.33 3.4 49 1.6

Flush/Fill Radiators 0 0 NA NA NA NA NA NA NA NA

Heat Treating Quench 136 76 0.00002 0.02 0.12 0.12 0.12 0.6 13 0.5

Heat Treating Rinse 36 34 0.0001 0.003 0.2 0.7 1.2 4.0 781 30

Hot Dip Coating 2 1 0.91 0.91 0.91 0.91 0.91 0.91 0.91 0.91

Hot Dip Coating Rinse 1 1 0.91 0.91 0.91 0.91 0.91 0.91 0.91 0.91

Impact Deformation 50 23 0.12 0.12 0.12 0.12 0.12 6.9 6.9 1.3

Impact Deformation Rinse 8 8 0.4 0.6 0.6 0.6 20.9 41 49 13.1

Laundering 1 1 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Mechanical Plating 4 4 0.013 0.021 0.034 0.097 0.185 0.24 0.282 0.122

Mechanical Plating Rinse 4 4 0.44 0.55 0.71 1.0 1.34 1.58 1.73 1.0

Metal Spray (Incl. Water

Curtains)

10 4 0.03 0.30 0.69 0.91 0.91 0.91 0.91 0.69

Painting Spray (Incl. Water

Curtains)

170 130 0.000062 0.002 0.02 0.04 0.04 0.10 1.52 0.08

Painting Spray Rinse 16 16 0.00025 0.01 0.04 0.12 0.80 1.3 2.5 0.49

Painting Immersion 23 12 0.00004 0.00007 0.0005 0.02 0.02 0.19 54.6 4.6

Painting Immersion Rinse 18 16 0.002 0.008 0.022 0.06 0.43 12.3 28.8 3.4

Phosphor Deposition 1 1 2.29 2.29 2.29 2.29 2.29 2.29 2.29 2.29

Phosphor Deposition Rinse 1 1 2.29 2.29 2.29 2.29 2.29 2.29 2.29 2.29

Photo Imaging Developing 125 114 0.0007 0.006 0.034 0.096 0.33 0.80 45.15 0.83

Photo Imaging Developing Rinse 113 112 0.046 0.26 1.30 1.74 2.95 7.95 65.97 4.14

Photo Resist Applications 6 4 0.001 0.002 0.003 0.012 0.25 0.66 0.93 0.24

Photo Resist Applications Rinse 2 2 0.032 2.4 5.9 11.8 17.8 21.3 23.7 11.8
15-71

15.0 - Permitting Guidance

Table 15-1 (a) (Continued)

Unit Operation

Total

Occurrences

Number of 

PNF

Calculations

Minimum

PNF

(gal/ft2)

10th

PNF

Percentile

(gal/ft2)

25th

PNF

Percentile

(gal/ft2)

Median

PNF

(gal/ft2)

75th

PNF

Percentile

(gal/ft2)

90th

PNF

Percentile

(gal/ft2)

Maximum

PNF

(gal/ft2)

Mean

PNF

(gal/ft2)

Physical Vapor Deposition 0 0 NA NA NA NA NA NA NA NA

Physical Vapor Deposition Rinse 0 0 NA NA NA NA NA NA NA NA

Plastic Wire Extrusion 0 0 NA NA NA NA NA NA NA NA

Plastic Wire Extrusion Rinse 0 0 NA NA NA NA NA NA NA NA

Polishing 60 33 0.0002 0.22 0.48 0.48 0.48 3.92 62 3.4

Polishing Rinse 27 24 0.0002 0.1 1.28 4.47 6.2 19.5 60 9.1

Pressure Deformation 55 37 0.105 0.12 0.12 0.12 0.12 0.12 6.9 0.48

Pressure Deformation Rinse 11 11 0.14 0.68 0.68 0.68 21.2 37.4 50.2 12.4

Salt Bath Descaling 3 2 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12

Salt Bath Descaling Rinse 5 5 0.68 0.68 0.68 0.68 2 12.8 20 4.8

Shot Tower-Lead Shot

Manufacturing

0 0 NA NA NA NA NA NA NA NA

Shot Tower-Lead Shot

Manufacturing Rinse

0 0 NA NA NA NA NA NA NA NA

Soldering/Brazing 61 15 0.002 0.011 0.16 0.91 0.95 13.4 26.4 3.8

Soldering/Brazing Rinse 45 39 0.26 0.91 0.91 0.91 1.7 15.3 454 17.1

Solder Flux Cleaning 45 11 0.001 0.002 0.007 0.018 0.13 1.7 7.7 0.88

Solder Flux Cleaning Rinse 40 40 0.012 0.18 0.49 1.60 4.9 14.6 34 4.8

Solder Fusing 26 10 0.0005 0.004 0.007 0.01 0.04 0.51 3.7 0.40

Solder Fusing Rinse 23 23 0.07 0.32 0.50 1.2 5.8 17.8 60 6.7

Solvent Degreasing 47 9 0.013 0.013 0.013 0.013 0.028 1.17 5.2 0.013

Solvent Degreasing Rinse 26 26 0.17 0.72 0.80 0.80 2.4 30 1713 74.1

Sputtering 0 0 NA NA NA NA NA NA NA NA

Sputtering Rinse 0 0 NA NA NA NA NA NA NA NA

Steam Cleaning 2 2 0.013 12.5 31.26 62.5 93.8 112.5 125 62.5

Stripping Paint 162 140 0.0005 0.005 0.02 0.03 0.05 0.22 1.7 0.09

Stripping Paint Rinse 160 156 0.02 0.16 0.51 1.30 3.5 11.8 113 5.7

Stripping Metallic Coating 252 217 0.0002 0.004 0.014 0.03 0.09 0.42 61 0.72
15-72

15.0 - Permitting Guidance

Table 15-1 (a) (Continued)

Unit Operation

Total

Occurrences

Number of 

PNF

Calculations

Minimum

PNF

(gal/ft2)

10th

PNF

Percentile

(gal/ft2)

25th

PNF

Percentile

(gal/ft2)

Median

PNF

(gal/ft2)

75th

PNF

Percentile

(gal/ft2)

90th

PNF

Percentile

(gal/ft2)

Maximum

PNF

(gal/ft2)

Mean

PNF

(gal/ft2)

Stripping Metallic Coating Rinse 214 209 0.003 0.22 0.65 2.1 9.6 40 5954 67

Testing 256 231 0.0004 0.59 0.59 0.59 0.59 0.75 79.5 2.2

Testing Rinse 69 69 0.01 0.15 0.59 0.59 0.95 6.8 1197 22.5

Thermal Cutting 22 8 0.12 0.18 0.20 0.64 0.91 0.91 0.90 0.57

Thermal Infusion 1 1 0.91 0.91 0.91 0.91 0.91 0.91 0.91 0.91

Thermal Infusion Rinse 0 0 NA NA NA NA NA NA NA NA

Ultrasonic Machining 0 0 NA NA NA NA NA NA NA NA

Ultrasonic Machining Rinse 0 0 NA NA NA NA NA NA NA NA

Vacuum Impregnation 4 1 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5

Vacuum Impregnation Rinse 2 2 1.9 1.9 14 26 38.3 45.5 50.4 26

Vacuum Plating 0 0 NA NA NA NA NA NA NA NA

Vacuum Plating Rinse 0 0 NA NA NA NA NA NA NA NA

Washing Finished Products 299 250 0.00002 0.007 0.013 0.01 0.20 3.8 941 6.4

Washing Finished Products Rinse 123 119 0.002 0.02 0.08 0.70 0.83 3.0 78.9 2.6

Water Shedder 0 0 NA NA NA NA NA NA NA NA

Water Shedder Rinse 0 0 NA NA NA NA NA NA NA NA

Welding 95 26 0.00004 0.003 0.28 0.90 0.91 3.71 12.5 1.6

Welding Rinse 6 6 0.01 0.16 0.32 0.62 11 22.5 30.7 7.8

NA - Not applicable.
15-73

15.0 - Permitting Guidance

Table 15-1 (b)

Descriptive Statistics of MP&M Survey Data for Unit Operations with Pounds of Metal Removed as the

Production-Normalizing Parameter

Unit Operation

Total

Occurrences

Number of

PNF

Calculations

Minimum

PNF

(gal/lb met

rem)

10th

Percentile

(gal/lb met

rem)

25th

Percentile

(gal/lb met

rem)

Median

PNF

(gal/lb met

rem)

75th

Percentile

(gal/lb met

rem)

90th

Percentile

(gal/lb met

rem)

Maximum

PNF

(gal/lb met

rem)

Mean

PNF

(gal/lb met

rem)

Abrasive Jet Machining 6 6 0.0009 0.003 0.009 0.02 0.02 0.04 0.06 0.02

Abrasive Jet Machining

Rinse

0 0 NA NA NA NA NA NA NA NA

Electrical Discharge

Machining

34 12 0.04 0.16 0.65 1.7 4.4 14.9 450 40.4

Electrical Discharge

Machining Rinse

3 2 1 1.08 1.2 1.4 1.6 1.7 1.8 1.4

Grinding 511 427 0.0003 0.033 0.093 0.12 0.64 5.6 36000 247

Grinding Rinse 47 40 0.0007 0.2 20.7 318 1551 6370 291800 466

Machining 1369 1143 0.0003 0.11 0.05 0.12 0.18 1.7 376 1.6

Machining Rinse 21 19 0.001 0.02 0.09 0.7 319 338 376 109

Plasma Arc Machining 37 25 0.35 2 2 2 2 2.6 22 2.9

NA - Not applicable.
15-74

15.0 - Permitting Guidance

Table 15-2

Water Conservation Methods for Surface Treatment Rinses

Practice

Alkaline

Clean

Acid

Clean

Hexavalent

Chromium

Trivalent

Chromium

Cadmium

Zinc

Cyanide

Cadmium

Zinc NonCyanideAcid

Copper

Copper

Cyanide

Watts,

Woods,

Other

Nickels

Electroless

Nickel

Silver

Cyanide

Gold

Cyanide

Lead,

LeadTin TinChromatePhosphate

ChromicAcid

Anodize

Sulfuric

Anodize

Drag-out Reduction and Recovery 

Fog or spray rinsing

over tank

(110E F or higher) 

T T T T T T T T

a T T

Controlled slow

withdrawal

T T T T T T T T T T T T T T T T T T

Addition of wetting

agent (when

compatible)

T T T T T T T T T T T T T T T T

Positioning work piece T T T T T T T T T T T T T T T T T T

Long drip time T T T T T T T T T T T T T T T T

Drip shield T T T T T T T T T T T T T T T T T T

Air knife T T T T T T T T T T T

Drag-out tank

(heated)

T T T T T T T T T T T T T T T

Drag-in/out tank T T T T T T T T T T T T T T T

Lowest concentration T T T T T T T T T T T T T T T T T T

Highest temperature T T T T T T T T T T T T T T T T T

Rinse Tank Design and Innovative Configuration

Countercurrent rinse T T T T T T T T T T T T T T T T T T

Cascading rinse

(cleaning)

T T

Spray rinse T T T T T T T T T T T T T T T T T T

Good tank designb T T T T T T T T T T T T T T T T T T
15-75

15.0 - Permitting Guidance

Table 15-2 (Continued)

Practice

Alkaline

Clean

Acid

Clean

Hexavalent

Chromium

Trivalent

Chromium

Cadmium

Zinc

Cyanide

Cadmium

Zinc NonCyanideAcid

Copper

Copper

Cyanide

Watts,

Woods,

Other

Nickels

Electroless

Nickel

Silver

Cyanide

Gold

Cyanide

Lead,

LeadTin TinChromatePhosphate

ChromicAcid

Anodize

Sulfuric

Anodize

Rinse Water Use Control

Flow restrictors T T T T T T T T T T T T T T T T T T

Timer controls T T T T T T T T T T T T T T T T T T

Conductivity controls T T T T T T T T T T T T T T T T T T

Metal Recovery and Rinse Water Reuse Technologies

Evaporatorc T T T T T T T T T T T T T T T

Ion exchangec T T T T T T T T T T

Electrolytic Recovery T T T T T T T T

Electrodialysisc T T T T 

Reverse osmosisc T T T T T T T T

Source: MP&M Site Visits, MP&M surveys, Technical Literature.

aAlkaline tin only.

bFor example: Air or other agitation, minimum size, and inlet, outlet location opposite ends.

cOnly common applications of this technology are checked.
15.0 - Permitting Guidance

15-76

Table 15-3

Definitions of Pollution Prevention 

and Water Conservation Practices and Technologies

Practice or 

Technology Definition

Air Knife Air knives are usually installed over a process tank or drip shield and are designed to

remove drag-out by blowing it off the surface of parts and racks. Drag-out is routed

back to the process tank. Air knives are more effective with flat parts. Air knives

cannot be used to dry surfaces that passivate or stain due to oxidation. 

Cascade Rinse Cascade rinsing is a method of reusing rinse water. Rinse water from one rinsing

operation is plumbed to another, less critical one before being discharged to

treatment. Some rinse waters acquire chemical properties, such as low pH, that make

them desirable for reuse in specific rinse systems. This is generally referred to as

reactive rinsing.

Conductivity

Controller 

Conductivity probes measure the conductivity of water in a rinse tank to regulate the

flow of fresh rinse water into the rinse system. Conductivity controllers consist of a

controller, a meter with adjustable set points, a probe that is placed in the rinse tank,

and a solenoid valve. As parts are rinsed, dissolved solids are added to the water in

the rinse tank, raising the conductivity of the water. When conductivity reaches the

set point, the solenoid valve is opened to allow make-up water to enter the tank. 

When the conductivity falls below the set point, the valve is shut to discontinue the

make-up water.

In theory, conductivity control of rinse flow is a precise method of maintaining

optimum rinsing conditions in intermittently used rinse operations. In practice,

conductivity controllers work best with deionized rinse water. Incoming water

conductivity may vary day to day and season to season, which forces frequent setpoint adjustments. Suspended solids and nonionic contaminants (e.g., oil) are not

detected by the conductivity probe and can cause inadequate rinsing.

Countercurrent

Cascade Rinse

Countercurrent cascade rinsing refers to a series of consecutive rinse tanks that are

plumbed to cause water to flow from one tank to another in the direction opposite of

the work flow. Countercurrent cascade rinsing is widely used to reduce the discharge

rate of rinse water. Fresh water flows into the rinse tank located farthest from the

process tank and overflows, in turn, to the rinse tanks closer to the process tank. This

technique is termed countercurrent rinsing, because the work piece and the rinse

water move in opposite directions. Over time, the first rinse becomes contaminated

with drag-out and reaches a stable concentration that is lower than the process

solution. The second rinse stabilizes at a lower concentration, which enables less

rinse water to be used than if only one rinse tank were in place. The more

countercurrent cascade rinse tanks (three-stage, four-stage, etc.), the less water is

needed to adequately remove the process solution. 
Table 15-3 (Continued)

15.0 - Permitting Guidance

Practice or 

Technology Definition

15-77

Drag-in/Drag-out

Rinsing

A drag-in/drag-out rinse system may be a single tank or two tanks plumbed together. 

Parts enter the rinse system before and after processing in the bath. As parts enter the

process bath, they drag in process chemicals present in the drag-in/drag-out rinse

rather than plain rinse water. This rinsing configuration is an effective recovery

method for process baths that have low evaporation rates.

Drag-out Tank Drag-out tanks are rinse tanks that are initially filled with water and remain stagnant. 

Parts are rinsed in drag-out tanks directly after exiting the process bath. Gradually,

the concentration of process chemicals in the drag-out tank rises. In the most

efficient configuration, a drag-out tank is used after a heated process tank that has a

moderate to high evaporation rate. Part of the fluid in the drag-out tank is returned to

the process tank to replace the evaporative loss. The level of fluid in the drag-out

tank is maintained by adding fresh water. 

Drip Shields Drip shields are installed between process tanks and rinse tanks to recover process

fluid dripping off racks and barrels that would otherwise fall into rinse tanks or onto

the floor. Often, drip shields are an inclined piece of polypropylene or other material

that is inert to the process. 

Drip Tanks Drip tanks are similar to drag-out tanks except they are not filled with water. Parts

exiting a process bath are held over the drip tank and the process fluid that drips from

the parts is collected in the tank. When enough fluid is collected in the drip tank, it is

returned to the process tank. Drip tanks are generally considered to be a less

effective drag-out recovery practice than using drag-out tanks.

Electrodialysis Electrodialysis is a membrane technology used to remove impurities from and recover

process solutions. With this technology, a direct current is applied across a series of

alternating anion and cation exchange membranes to remove dissolved metal salts

and other ionic constituents from solutions.

An electrodialysis unit consists of a rectifier and a membrane stack. The stack

consists of alternating anion- and cation-specific membranes that form compartments. 

As the feed stream enters the unit, each alternating membrane compartment becomes

filled with either diluate or concentrate. When the compartments are filled, a direct

current is applied across the membrane. Cations in a diluate compartment traverse

one cation-specific membrane in the direction of the cathode, and are trapped in that

compartment by the next membrane, which is anion-specific. Anions from the

neighboring diluate compartment traverse the anion-specific membrane in the

direction of the anode, joining the cations, and are likewise trapped in the concentrate

compartment by the next cation-specific membrane. In this way, the feed stream is

depleted of ions, and anions and cations are trapped in each concentrate

compartment.

The feed stream is often from the first rinse tank in a countercurrent series, with a

concentration of 5 g/L or more of TDS. The concentrate, with a TDS concentration

of 50 g/L or more, and a volume of less than 10% of the feed stream, is returned to

the process. The diluate, representing more than 90% of the feed stream at a TDS

concentration of typically 1 g/L or less, is recycled as rinse water or discharged to

treatment.
Table 15-3 (Continued)

15.0 - Permitting Guidance

Practice or 

Technology Definition

15-78

Electrolytic Recovery

(Electrowining)

Electrolytic recovery is an electrochemical process used to recover metals from many

types of process solutions, such as electroplating rinse waters and baths. Electrolytic

recovery removes metal ions from a wastestream by processing the stream in an

electrolytic cell, which consists of a closely spaced anode and cathode. Commercial

equipment consists of several cells, a transfer pump, and a rectifier. Current is

applied across the cell and metal cations are deposited on the cathodes. The

wastestream is usually recirculated through the cell from a separate tank, such as a

drag-out recovery rinse. 

Electrolytic recovery is typically applied to solutions containing nickel, copper,

precious metals, and cadmium. Chromium and aluminum are poor candidates for

electrolytic recovery. Drag-out recovery rinses and ion-exchange regenerant are

common solutions that are processed using electrolytic recovery. Some solutions

require pH adjustment prior to electrolytic recovery. Acidic, metal-rich, cation

regenerant is an excellent candidate stream for electrolytic recovery, and is often

electrolytically recovered without adjustment. In some cases, when the target

concentration is reached, the wastestream is reused as cation regenerant.

Evaporation Evaporation is a common chemical recovery technology. There are two basic types

of evaporators: atmospheric and vacuum. Atmospheric evaporators, the more

prevalent type, are relatively inexpensive to purchase and easy to operate. Vacuum

evaporators are mechanically more sophisticated and are more energy efficient. 

Vacuum evaporators are typically used when evaporation rates greater than 50 to 70

gal/hour are required. Additionally, with vacuum evaporators, evaporated water can

be recovered as a condensate and reused on site.

A disadvantage of evaporation-based recovery is that all drag-out, including

unwanted components, are returned and accumulate in the process bath. For this

reason, deionized water is preferred as rinse water to prevent the introduction of

water contaminants in the process bath.

Flow Restrictor Flow restrictors prevent the flow in a pipe from exceeding a predetermined volume. 

They are commonly installed on a rinse tank’s water inlet. These devices contain an

elastomer washer that flexes under pressure to maintain a constant water flow

regardless of pressure. Flow restrictors can maintain a wide range of flow rates, from

less than 0.1 gal/min to more than 10 gal/min. 

As a stand-alone device, a flow restrictor provides a constant water flow. As such,

for intermittent rinsing operations, a flow restrictor does not coordinate the rinse flow

with drag-out introduction. Precise control with intermittent operations typically

requires a combination of flow restrictors and rinse timers. However, for continuous

rinsing (e.g., continuous electroplating machines), flow restrictors may be adequate

for good water control. 

Fog or Spray Rinse

Over Tank

Fog or spray rinsing is performed over a process bath to recover drag-out. Draining

over a process bath can be greatly enhanced by spray or fog rinsing, which dilutes

and lowers the viscosity of the film of process fluid clinging to the parts. This

method of drag-out recovery is only possible if the evaporation rate of the process

fluid is moderate to high.
Table 15-3 (Continued)

15.0 - Permitting Guidance

Practice or 

Technology Definition

15-79

Good Tank Design Rinse tanks should be designed to remove the drag-out layer from the part and cause

it to rapidly and thoroughly mix with the rinse water. Common elements of good

tank design are positioning the inlet and outlet at opposite ends of the tank, using air

or other agitation, using a flow distributor, and using the minimum size of tank

possible. 

Ion Exchange Ion exchange is a reversible chemical reaction that exchanges ions in a feed stream

for ions of like charge on the surface of an ion-exchange resin. Resins are broadly

divided into cationic or anionic types. Typical cation resins exchange H+ for other

cations, while anion resins exchange OH- for other anions. 

In practice, a feed stream is passed through a vessel, referred to as a column, which

holds the resin. The feed stream is typically dilute rinse water. The exchange

process proceeds until the capacity of the resin is reached (i.e., an exchange has

occurred at all the resin sites). A regenerant solution is then passed through the

column. For cation resins, the regenerant is an acid, and the H+ ions replace the

cations captured from the feed stream. For anion resins, the regenerant is a base, and

OH- ions replace the anions captured from the feed stream. The concentration of

feed stream ions is much higher in the regenerant than in the feed stream; therefore,

the ion-exchange process accomplishes both separation and concentration.

Ion exchange is used for water recycling and/or metal recovery. For water recycling,

cation and anion columns are placed in series. The feed stream is deionized and the

product water is reused for rinsing. Often, closed-loop rinsing is achieved. The

regenerant from the cation column typically contains the metal species, which can be

recovered in elemental form via recovery. The anion regenerant is typically

discharged to wastewater treatment. When metal recovery is the only objective, a

single or double cation column unit containing selective resin is used. These resins

attract divalent cations while allowing monovalent cations to pass, a process usually

referred to as metal scavenging. Water cannot be recycled because contaminants

other than the target cations remain in the stream exiting the column.

Long Drip Time Long drip times over the process tank reduce the volume of drag-out reaching the

rinsing system. Automatic lines can be easily programmed to include optimum drip

times. On manual lines, racks are commonly hung on bars over process baths and

allowed to drip. Barrels can be rotated over the process bath to enhance drainage. 

Some surfaces cannot tolerate long exposure to air due to oxidation or staining, and

would therefore be unsuitable for extended drip times. 

Raising Bath

Temperature

Bath temperature and viscosity are inversely related. Operating at the highest

possible bath temperature lowers viscosity and reduces drag-out. Higher bath

temperatures also increase evaporation, which facilitates efficient recovery rinsing.

Lowering Bath

Concentration

Operating at the lowest possible concentration reduces the mass of chemicals in a

given volume of drag-out. Also, viscosity and concentration are directly related and

lower process bath concentration lowers viscosity and reduces drag-out volume. 

Contaminants and other substances that build in concentration over the life of a

process bath should be controlled at a low level, if possible.
Table 15-3 (Continued)

15.0 - Permitting Guidance

Practice or 

Technology Definition

15-80

Part Position on Rack Positioning parts on racks to promote rapid draining includes minimizing the profile

of the parts emerging from the bath, tilting and inverting cup-shaped parts, and

avoiding placement of parts directly atop one another. 

Slow Part Withdrawal The faster a part is removed from a process bath, the thicker the layer of fluid

clinging to the part will be. A slower withdrawal rate reduces the thickness of the

fluid layer and reduces drag-out. Generally, this method of drag-out reduction can

only be practiced on automatic lines where the withdrawal velocity can be

programmed.

Reverse Osmosis Reverse osmosis is a membrane separation technology used for chemical recovery. 

The feed stream, usually relatively dilute rinse water or wastewater, is pumped to the

surface of the reverse osmosis membrane at pressures of 400 to 1,000 psig. The

membrane separates the feed stream into a reject stream and a permeate. The reject

stream, containing most of the dissolved solids in the feed stream, is deflected from

the membrane while the permeate passes through. Reverse osmosis membranes

reject more than 99% of multivalent ions and 90% to 96% of monovalent ions, in

addition to organic pollutants and nonionic dissolved solids. The permeate stream is

usually of sufficient quality to be recycled as rinse water, despite the small

percentage of monovalent ions (commonly potassium, sodium and chloride) that pass

through the membrane.

A sufficiently concentrated reject stream can be returned directly to the process bath. 

The reject stream concentration can be increased by recycling the stream through the

unit more than once or by increasing the feed pressure. In multiple-stage units

containing more than one membrane chamber, the reject stream from the first

chamber is routed to the second, and so on. The combined reject streams from

multistage units may, in some cases, have high enough concentrations to be returned

directly to the bath. 

Timer Rinse

Controller

Rinse timers are electronic devices that control a solenoid valve. The timer usually

consists of a button that, when pressed, opens the valve for a predetermined length of

time, usually from 1 to 99 minutes. When the valve is open, make-up water is

allowed to flow into a given tank. After the time period has expired, the valve is

automatically shut. The timer may be activated either manually by the operator or

automatically by the action of racks or hoists.

Most rinse systems that are used intermittently benefit from the installation of a rinse

timer, as operator error is eliminated. Rinse timers installed in conjunction with flow

restrictors can provide precise control when the incoming water pressure may rise

and fall. Rinse timers are less effective in continuous or nearly continuous rinse

operations (e.g., continuous electroplating machines).

Wetting Agents Wetting agents or surfactants may be added to some process baths to reduce viscosity

and surface tension, thereby significantly reducing drag-out.

Source: MP&M Site Visits, MP&M Surveys, Technical Literature.
15-81

15.0 - Permitting Guidance

Table 15-4

Factors Affecting Drag-Out

Factor Affecting

Drag-Out Impact on Drag-out

Potential Pollution Prevention and Water Conservation

Practices

Restrictions

Bath Concentration Concentration and drag-out are directly

related.

Operate at lowest concentration possible. Remove all

contaminants promptly.

Concentration range limited by process.

Bath Temperature Higher temperatures lower drag-out by

lowering viscosity.

Operate at highest possible temperature. Temperature range limited by process.

Bath Viscosity High viscosity raises drag-out by

increasing the thickness of the fluid layer

clinging to the part.

Operate at highest temperature and lowest concentration

possible. Add wetting agent.

Concentration and temperature ranges limited by

process. Wetting agent must be compatible.

Part Configuration Cup shapes result in 8-20 times the dragout volume of flat shapes.Drain holes can be added to many cup-shaped parts to

improve drainage of drag-out.

Functionality of parts may restrict use of drain holes

or other changes to part configuration.

Part Orientation Orientation on rack can be optimized to

minimized drag-out.

Keep records of optimal orientations. Train operators. None.

Withdrawal Rate Doubling speed of withdrawal results in a

fourfold increase in drag-out volume.

Program automatic equipment for slow withdrawal. Impossible to consistently practice without

automation.

Drain Time Long drain times and barrel rotations

greatly reduce drag-out.

Program automatic equipment for long drain times. Impossible or difficult to consistently practice without

automation. Drain time limited by staining or

passivation of some coatings.

Rack versus Barrel Barrels produce greater drag-out than

racks. 

(See “Rack/Barrel Design) Part transport device is dictated by part size.

Rack/Barrel Design Drag-out volume is related to barrel design. Redesign barrels with largest holes possible. Barrel design limited by part sizes and configurations.

Rack/Barrel Condition Loose rack coating cause reservoirs of fluid

to be transported with rack.

Maintain a schedule of maintenance and recoating. None

Operator Awareness Poor operator awareness greatly increases

drag-out or offsets other practices.

Require training programs for operators. None

Source: MP&M Site Visits, MP&M Surveys, Technical Literature.
15-82

15.0 - Permitting Guidance

Table 15-5

Rinse-water Required for Various Plating Processes Based on Literature Valuesa

Process

Rinse

Configuration

TDS

Concentration

Target TDS

Concentration in

Rinse Part Type Drag-out Rate

PNF

gal/ft2

100% Control

PNF gal/ft2

100%

Excess

Acid Zinc Single overflow 166 g/L Functional: 100-

700 mg/L (used

400 mg/L)

Flat 1.3 gal/1,000 ft20.54 1.1

Contoured 3.5 gal/1,000 ft21.5 2.9

2-stage

countercurrent

cascade

166 g/L Functional: 100-

700 mg/L (used

400 mg/L)

Flat 1.3 gal/1,000 ft20.024 0.048

Contoured 3.5 gal/1,000 ft20.072 0.14

Silver Cyanide Single overflow 370 g/L Bright: 5-40 mg/L 

(used 20 mg/L)

Flat 1.2 gal/1,000 ft222 44

Contoured 3.2 gal/1,000 ft258 120

2-stage

countercurrent

cascade

370 g/L Bright: 5-40 mg/L 

(used 20 mg/L)

Flat 1.2 gal/1,000 ft20.16 0.32

Contoured 3.2 gal/1,000 ft20.43 0.87
15-83

15.0 - Permitting Guidance

Table 15-5 (Continued)

Process

Rinse

Configuration

TDS

Concentration

Target TDS

Concentration in

Rinse Part Type Drag-out Rate

PNF

gal/ft2

100% Control

PNF gal/ft2

100%

Excess

Copper

Cyanide

Single overflow 250 g/L Functional: 100-

700 mg/L (used

400 mg/L)

Flat 0.91 gal/1,000 ft20.57 1.1

Contoured 3.2 gal/1,000 ft22.0 4.0

2-stage

countercurrent

cascade

250 g/L Functional: 100-

700 mg/L (used

400 mg/L)

Flat 0.91 gal/1,000 ft20.023 0.046

Contoured 3.2 gal/1,000 ft20.081 0.16

Acid Descale Single Overflow 248 g/L Clean: 400-1000

mg/L (used 700

mg/L)

Flat 1 gal/1,000 ft2

(estimated)

3.5 7.1

Contoured 3 gal/1,000 ft2

(estimated)

11 21

2-stage

countercurrent

cascade

248 g/L Clean: 400-1000

mg/L (used 700

mg/L)

Flat 1 gal/1,000 ft2

(estimated)

0.019 0.038

Contoured 3 gal/1,000 ft2

(estimated)

0.056 0.11
15-84

15.0 - Permitting Guidance

Table 15-5 (Continued)

Process

Rinse

Configuration

TDS

Concentration

Target TDS

Concentration in

Rinse Part Type Drag-out Rate

PNF

gal/ft2

100% Control

PNF gal/ft2

100%

Excess

Alkaline 

Clean

(Proprietary

Chemistry)

Single overflow 90 g/L Clean: 400-1000

mg/L (used 700

mg/L)

Flat 1 gal/1,000 ft2

(estimated)

0.13 0.26

Contoured 3 gal/1,000 ft2

(estimated)

0.39 0.77

2-stage

countercurrent

cascade

90 g/L Clean: 400-1000

mg/L (used

700 mg/L)

Flat 1 gal/1,000 ft2

(estimated)

0.011 0.022

Contoured 3 gal/1,000 ft2

(estimated)

0.033 0.066

aTDS concentrations are from References 3 and 4, based on bath formulations. Target TDS concentrations are based on criteria presented in Section 3.2.1

(Reference 1). Drag-out rates are from References 1 and 2 unless data were not available, in which case rates were assumed based on technical knowledge of the

operations.

Sources: References 1, 3, and 4.
15.0 - Permitting Guidance

15-85

Q '

DCo

Ce

& D

M

Ce'

D

QM % D

Co

Q '

D

M

Co

Cr

1/n

1. Acid zinc formulation:

ZnSO4(7H2O) 240 g/L

NH4Cl 15 g/L

Al2(SO4)3(18H2O) 30 g/L

Licorice 1 g/L

 2. Equation used to calculate rinse flow and flow per square foot for single overflow rinse:

Solving for Q: 

Where:

D = Drag-out per ft2 (gal) Ce = Target concentration of rinse (oz/gal)

Co = Concentration of process bath (oz/gal) Cr = Target concentration of final rinse

(oz/gal)

M = Interval between drag-out events (minutes) Q = Flow (gal/min)

Note: Any interval M can be chosen. Q, when divided by the work rate, ft2/M, yields the gal/ft2 in the table and

the gal/ft2 number remains the same for any M.

3. Equation used to calculate 100% controlled flow and gallons per square foot for countercurrent cascade

rinse:

Where n = number of rinse stages 

For 50% controlled flow, Q was multiplied by a factor of 2.

With 100% controlled flow, the introduction of drag-out and rinsewater into the rinse tank are perfectly coordinated

and, therefore, the rinsewater required to meet the target concentration of the final rinse is equal to Q. With 100%

excess flow, the introduction of drag-out and rinsewater are not perfectly coordinated and an excess of 100% of Q

(or 2Q) is used to meet the target concentration of the final rinse. 
15.0 - Permitting Guidance

15-86

4. Silver cyanide formulation (middle of high-speed bath range): 

AgCN 97.5 g/L

KCN 152.5 g/L

K2CO3 52.5 g/L

KNO3 50 g/L

KOH 17 g/L

5. High-efficiency copper cyanide formulation:

CuCN 75 g/L

KCN 133 g/L

KOH 42 g/L

6. Acid descale formulation:

20% H2NO3 (by volume)

1.5% HF (by volume)

All bath formulations and equations are from References 1, 3, and 4.
15.0 - Permitting Guidance

15-87

Table 15-6

Adjusted Production-Normalized Flow (PNF) Data for Countercurrent

Cascade-Rinses

Measured PNF

(gal/ft2)

Measured TDS

(mg/L)

Adjusted TDS

(mg/L)a

Adjusted PNF

(gal/ft2)

b Part Description

CLEANING RINSES WITH FLOW CONTROL

(Includes timed rinses, conductivity sensors, flow restrictors, and manual shut-off)

0.031 1,600 700 0.047 Doorknob components

0.037 1,800 700 0.059 Doorknob components

0.054 1,700 700 0.084 Doorknob components

0.26 1,300 700 0.36 Doorknob components

0.26 2,000 700 0.44 Doorknob components

0.26 1,100 700 0.33 Doorknob components

0.30 1,100 700 0.37 Doorknob components

0.38 1,100 700 0.48 Doorknob components

0.49 1,400 700 0.69 Doorknob components

0.49 940 700 0.56 Doorknob components

0.62 1,200 700 0.81 Doorknob components

0.62 860 700 0.68 Doorknob components

PLATING AND CONVERSION COATING RINSES WITH FLOW CONTROL

(Includes timed rinses, conductivity meters, flow restrictors, and manual shut-off)

0.017 400 3,900 0.15 Shafts for mobile industrial

equipment

0.037 400 4,100 0.350 Shafts for mobile industrial

equipment

0.16 400 4,100 1.5 Shafts for mobile industrial

equipment

0.83 720 400 0.350 Doorknob Components

1.5 730 400 1.5 Doorknob components

Source: Sampling episode data from two MP&M sites.

aAdjusted TDS based on rinsing criteria presented in Section 3.1.2 (Reference 1).

bThe adjusted PNFs account for the fact that the TDS was measured from the discharge of first tank in the

countercurrent cascade series. EPA assumes the TDS present in the measured rinse is entirely composed of dragout and that the rinse water supplied is deionized. 
15.0 - Permitting Guidance

15-88

Table 15-7 

Pollution Prevention and Water Conservation Methods Applicable to

Machining Operations

Pollution Prevention/Water

Conservation Method Examples Applicability

Prevention of Metal-Working Fluid Contamination

Reduce contamination from tramp

oil

Use coolant in hydraulic and other

oil systems.

Applicable to most machines. In

most cases, requires use of special

fluid.

Replace hydraulics with electrical

systems.

Limited applicability. Practical

only during major equipment

overhaul. 

Machine maintenance. Applicable to all machines. Should

be performed at regularly

scheduled intervals.

Reduce contamination from makeup waterUse deionized water for initial

make-up of working fluid and to

account for evaporative losses. 

Applicable to all machining

operations using a water-soluble

fluid. Especially important in areas

where the water supply is high in

TDS.

Reduce contamination from sumps Sterilize sumps during clean-out

using steam.

Applicable to all machining

operations. Especially important

with large concrete sumps.

Use metal inserts or coat walls of

concrete sumps.

Applicable to in-ground concrete

sumps.

Extension of Metal-Working fluid Life

Raw material substitution Use high quality fluids with needed

“additive package.”

Most machining operations can

benefit from the use of high-quality

fluids that can extend fluid life,

while reducing bacterial growth,

improving lubricity, reducing

friction, and providing corrosion

protection.
Table 15-7 (Continued)

15.0 - Permitting Guidance

Pollution Prevention/Water

Conservation Method Examples Applicability

15-89

Equipment modification Replace sump’s air agitation with

mechanical agitation.

Applicable to central sumps with

air agitation.

Install tramp oil removal device. Limited mainly to external sumps.

Fluid Monitoring Measure pH, coolant concentration,

tramp oil concentration, and

bacterial count weekly or more

frequently.

Applicable to all machining

operations. Larger operations can

use data for statistical process

control.

Metal-working fluid recycling Use methods and technologies for

removing fluid contaminants (e.g.,

filtration, centrifuge,

pasteurization).

Simple filtration methods can be

used by all machining operations. 

More sophisticated equipment is

limited to larger operations.

Recycle chip drainage. Applicable to all machining

operations. Requires clean

handling and storage methods to

prevent contamination.

Source: MP&M Site Visits, MP&M Surveys, Technical Literature.
15.0 - Permitting Guidance

15-90

Table 15-8

Pollution Prevention and Water Conservation Methods Applicable to

Painting Operations

Pollution Prevention/Water

Conservation Method Examples Applicability

Reduce the Quantity of Paint Entering the Water System

Improve spray painting

operating practices

Provide operator training to improve

racking and positioning of parts to

reduce over spray, assure proper

selection of nozzle for efficient spray

pattern, improve work scheduling and

reduce clean-outs, improve

housekeeping. 

Applicable to all spray painting

operations.

Improve paint transfer

efficiency

Replace inefficient conventional

compressed air spray equipment with

high-velocity/low-pressure equipment.

Applicable to most existing spray

painting operations using

conventional equipment. Will

require some retraining of

operators. 

Install gun cleaning station Use gun-cleaning station to clean guns

and lines. Can prevent spraying of

cleaning fluid/paint into booth. 

Applicable to most solvent-based

painting operations.

Recycle Paint Booth Water

Recycle paint booth water

through solids removal

Use booth water maintenance system

that removes paint solids. Applicable

technologies include weirs, filters, and

centrifuges.

Applicable to most water-wash

booths. Usually requires

treatment of booth water with

chemicals to produce solids that

can be separated from water.

Use Dry-Filter Booths

Use dry-filter booths instead

of water-wash booths

Convert existing water-wash booth to a

dry-filter booth.

Applicable to booths with low to

moderate paint usage. In cases of

high paint usage, dry filters clog

too quickly. 

Source: MP&M Site Visits, MP&M Surveys, Technical Literature.
15.0 - Permitting Guidance

15-91

Table 15-9

Pollution Prevention and Water Conservation Methods Applicable to

Cleaning Operations

Pollution

Prevention/Water

Conservation Method Examples Applicability

Housekeeping and

maintenance

Check the accuracy of temperature

controls; remove sludge build-up from

tanks, heat coils and temperature

regulators; retrieve parts, racks, etc.

dropped into the tanks; and check the

integrity of tanks and tank liners.

Applicable to all cleaning

operations.

Oil and suspended solids

removal

Technologies used to remove oil and

suspended solids from cleaning solutions,

thereby extending the useful life span of

the solutions (e.g., skimmers, coalescers,

cartridge and membrane filters).

Suspended solids removal equipment

(e.g., cartridge filters) are applicable

to nearly all baths. The other types

of equipment are applicable to most

or all alkaline cleaning baths.

Dissolved solids removal Various technologies and processes that

remove dissolved metals from baths,

including acid sorption, diffusion

dialysis, and membrane electrolysis.

Applicable to acid and alkaline

solutions that become contaminated

with dissolved metal, usually due to

etching of the basis metal.

Source: MP&M Site Visits, MP&M Surveys, Technical Literature.
16.0 - Glossary/List of Acronyms

16-1

16.0 GLOSSARY/LIST OF ACRONYMS

Act - The Clean Water Act.

Administrator - The Administrator of the U.S. Environmental Protection Agency.

Agency - U.S. Environmental Protection Agency (also referred to as “EPA”).

AWQC - Ambient Water Quality Criteria.

BAT - Best available technology economically achievable, as defined by section 304(b)(2)(B) of

the Clean Water Act.

BCT - Best conventional pollutant control technology, as defined by section 304(b)(4) of the

Clean Water Act.

BMP - Best management practices, as defined by section 304(e) of the Clean Water Act or as

authorized by section 402 of the Clean Water Act.

BOD5- Five-day biochemical oxygen demand. A measure of biochemical decomposition of

organic matter in a water sample. It is determined by measuring the dissolved oxygen consumed

by microorganisms to oxidize the organic contaminants in a water sample under standard

laboratory conditions of five days and 20EC. BOD5 is not related to the oxygen requirements in

chemical combustion.

BPT - Best practicable control technology currently available, as defined by section 304(b)(1) of

the Clean Water Act.

CAA - Clean Air Act (42 U.S.C. 7401 et seq., as amended inter alia by the Clean Air Act

Amendments of 1990 (Pub. L. 101-549, 104 stat. 2394)).

CBI - Confidential Business Information.

CE - Cost effectiveness.

CFR - Code of Federal Regulations, published by the U.S. Government Printing Office. A

codification of the general and permanent rules published in the Federal Register by the

executive departments and agencies of the federal government.

COD - Chemical oxygen demand. A nonconventional, bulk parameter that measures the

oxygen-consuming capacity of refractory organic and inorganic matter present in water or

wastewater. COD is expressed as the amount of oxygen consumed from a chemical oxidant in a

specific test (see Method 410.1).
16.0 - Glossary/List of Acronyms

16-2

Contract Hauling - The removal of any waste stream from the facility by a company authorized

to transport and dispose of the waste, excluding discharges to sewers or surface waters.

Control Authority - The term “control authority” as used in section 403.12 refers to: (1) The

POTW if the POTW’s submission for its pretreatment program (§403.3(t)(1)) has been approved

in accordance with the requirements of §403.11; or (2) the approval authority if the submission

has not been approved.

Conventional Pollutants - The pollutants identified in section 304(a)(4) of the Clean Water Act

and the regulations thereunder (i.e., biochemical oxygen demand (BOD5), total suspended solids

(TSS), oil and grease, fecal coliform, and pH).

CWA - Clean Water Act. The Federal Water Pollution Control Act Amendments

of 1972 (33 U.S.C. 1251 et seq.), as amended, inter alia, by the Clean Water Act of 1977

(Public Law 95-217) and the Water Quality Act of 1987 (Public Law 100-4).

DAF - Dissolved air flotation.

Direct Capital Costs - One-time capital costs associated with the purchase, installation, and

delivery of a specific technology. Direct capital costs are estimated by the MP&M cost model.

Direct Discharger - An industrial discharger that introduces wastewater to a water of the United

States with or without treatment by the discharger.

EEBA - Economic, Environmental, and Benefits Analysis of the Proposed Metal Products &

Machinery Rule. This document presents the methodology employed to assess economic and

environmental impacts and benefits of the proposed rule and the results of the analysis.

Effluent - Wastewater discharges.

Effluent Limitation - A maximum amount, per unit of time, production, volume, or other unit,

of each specific constituent of the effluent from an existing point source that is subject to

limitation. Effluent limitations may be expressed as a mass loading or as a concentration in

milligrams of pollutant per liter discharged.

Emission - Passage of air pollutants into the atmosphere via a gas stream or other means.

End-of-Pipe Treatment (EOP) - Refers to those processes that treat a facility waste stream for

pollutant removal prior to discharge.

EPA - The U.S. Environmental Protection Agency (also referred to as “the Agency”).

Facility - A place of business that conducts MP&M operations (also referred to as “site”).
16.0 - Glossary/List of Acronyms

16-3

Federally Owned Treatment Works (FOTW) - Any device or system owned and/or operated

by a United States federal agency to recycle, reclaim, or treat liquid sewage or liquid industrial

wastes.

FR - Federal Register, published by the U.S. Government Printing Office. A publication making

available to the public regulations and legal notices issued by federal agencies.

FTE - Full time equivalents (related to the number of employees).

HAP - Hazardous air pollutant.

Hazardous waste - Any material that meets the Resource Conservation and Recovery Act

definition of “hazardous waste” contained in 40 CFR Part 261.

Hexane Extractable Material (HEM) - A method-defined parameter (EPA Method 1664) that

measures the presence of relatively nonvolatile hydrocarbons, vegetable oils, animal fats, waxes,

soaps, greases, and related material that are extractable in the solvent n-hexane. This parameter

does not include materials that volatilize at temperatures below 85oC. EPA uses the term “HEM”

synonymously with the conventional pollutant oil and grease (O&G).

ICR - Information Collection Request.

Indirect Capital Costs - One-time capital costs that are not technology specific and are

represented as a multiplication factor that is applied to the direct capital costs estimated by the

MP&M cost model.

Indirect Discharger - An industrial discharger that introduces wastewater into a POTW.

Influent - Wastewater entering a facility wastewater treatment unit.

LTA - Long-term average. For purposes of the pretreatment standards, average pollutant levels

achieved over a period of time by a facility, subcategory, or technology option.

MACT - Maximum Achievable Control Technology (applicable to NESHAPs).

Metal Finishing Job Shop - A facility that owns 50 percent or less (based on metal surface area

processed per year) of the materials undergoing metal finishing on site.

Minimum Level - The lowest concentration that can be reliably measured by an analytical

method. 

Mixed-Use Facility - Any municipal, private, U.S. military or federal facility which contains

both industrial and commercial/administrative buildings at which one or more industrial sites

conduct operations within the facility’s boundaries.
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MP&M - Metal Products and Machinery Point Source Category.

NSCEP - EPA’s National Service Center for Environmental Publications. 

(http://www.epa.gov/ncepi)

NESHAP - National Emission Standards for Hazardous Air Pollutants.

New Source - As defined in 40 CFR 122.2 and 122.29, and 403.3(k), a new source is any

building, structure, facility, or installation from which there is or may be a discharge of

pollutants, the construction of which commenced for purposes of compliance with New Source

Performance Standards and Pretreatment Standards for New Sources after the promulgation of

the final rule under Clean Water Act sections 306 and 307(c). 

NRMRL - EPA’s National Risk Management Research Laboratory (formerly RREL - EPA’s

Risk Reduction Engineering Laboratory).

Noncontact Cooling Water - Water used for cooling which does not come into direct contact

with any raw material, intermediate product, by-product, waste product, or finished product. 

This term is not intended to relate to air conditioning systems.

Nonconventional Pollutant - Pollutants other than those defined specifically as conventional

pollutants (identified in section 304(a) of the Clean Water Act) or priority pollutants (identified

in 40 CFR Part 423, Appendix A).

Nondetect Value - Samples below the level that can be reliable measured by an analytical

method. This is also known, in statistical terms, as left-censored (i.e., value having an upper

bound at the sample-specific detection limit and a lower bound at zero).

Nonprocess Wastewater - Sanitary wastewater, noncontact cooling water, and storm water. In

relation to a mixed use facility, as defined in the MP&M effluent limitations guidelines and

standards (40 CFR Part 438), nonprocess wastewater for this part also includes wastewater

discharges from nonindustrial sources such as residential housing, schools, churches, recreational

parks, and shopping centers, as well as wastewater discharges from gas stations, utility plants,

hospitals, and similar sources.

Non-Water Quality Environmental Impact - An environmental impact of a control or

treatment technology, other than to surface waters, such as energy requirements, air pollution,

and solid waste generation.

NPDES - National Pollutant Discharge Elimination System, a federal program requiring industry

dischargers, including municipalities, to obtain permits to discharge pollutants to the nation’s

water, under section 402 of the Clean Water Act.

NRDC - Natural Resources Defense Council.
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NSPS - New source performance standards, under section 306 of the Clean Water Act.

OCPSF - Organic Chemicals, Plastics, and Synthetic Fibers Manufacturing Point Source

Category (40 CFR Part 414).

Off Site - Outside the boundary of the facility.

Oil and Grease (O&G) - A method-defined parameter (EPA Method 413.1) that measures the

presence of relatively nonvolatile hydrocarbons, vegetable oils, animal fats, (EPA nitrous 413.1)

waxes, soaps, greases, and related materials that are extractable in Freon 113 (1,1,2-trichloro1,2,2-trifluoroethane). This parameter does not include materials that volatilize at temperatures

below 75oC. Oil and grease is a conventional pollutant as defined in section 304(a)(4) of the

Clean Water Act and in 40 CFR Part 401.16. Oil and grease is also measured by the hexane

extractable material (HEM) method (see Method 1664, promulgated at 64 FR 26315; May 14,

1999). The analytical method for TPH and oil and grease has been revised to allow for the use of

normal hexane in place of Freon 113, a chlorofluorocarbon (CFC). Method 1664 (Hexane

Extractable Material) replaces the current oil and grease Method 413.1 found in 40 CFR 136.

On Site - Within the boundary of the facility.

Operating and Maintenance (O&M) Costs - Costs related to operating and maintaining a

treatment system, including the estimated costs for compliance wastewater monitoring of the

effluent.

ORP - Oxidation-reduction potential.

Point Source Category - A category of sources of water pollutants.

Pollutant of Concern - Pollutant parameter identified in MP&M sampling data that met the

following criteria: 1) the pollutant parameter was detected in at least three samples collected

during the MP&M sampling program: 2) the average concentration of the pollutant parameter in

samples of wastewater from MP&M unit operations and influents-to-treatment was at least five

times the minimum level, or the average concentration of effluents-from-treatment wastewater

samples exceeded five times the minimum level; and (3) the pollutant parameter was analyzed in

a quantitative manner (i.e., analysis was not used only for screening purposes and was subject to

quality assurance/quality control (QA/QC) procedures).

Pollution Prevention - The use of materials, processes, or practices that reduce or eliminate the

creation of pollutants or wastes. It includes practices that reduce the use of hazardous and

nonhazardous materials, energy, water, or other resources, as well as those practices that protect

natural resources through conservation or more efficient use. Pollution prevention consists of

source reduction, in-process recycle and reuse, and water conservation practices.
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Publicly Owned Treatment Works (POTW) - A treatment works as defined by section 212 of

the Clean Water Act, which is owned by a state or municipality (as defined by section 502(4) of

the Clean Water Act). This definition includes any devices and systems used in the storage,

treatment, recycling, and reclamation of municipal sewage or industrial wastes of a liquid nature. 

It also includes sewers, pipes, and other conveyances only if they convey wastewater to a POTW

treatment plant. The term also means the municipality as defined in section 502(4) of the Clean

Water Act, which has jurisdiction over the indirect discharges to and the discharges from such a

treatment works (40 CFR 403.3).

PPA - Pollutant Prevention Act of 1990 (42 U.S.C. 13101 et seq., Pub. L. 101-508,

November 5, 1990).

Priority Pollutants - The 126 pollutants listed in 40 CFR Part 423, Appendix A.

Privately Owned Treatment Works (PrOTW) - Any device or system owned and operated by

a private company that is used to recycle, reclaim, or treat liquid industrial wastes not generated

by that company.

Process Wastewater - Any water that, during manufacturing or processing, comes into direct

contact with or results from the production or use of any raw material, intermediate product,

finished product, by-product, or waste product. This includes wastewater from noncontact,

nondestructive testing (e.g., photographic wastewater from nondestructive X-ray examination of

parts) performed at facilities subject to MP&M effluent limitations guidelines and standards (40

CFR Part 438).

Production Normalized Flow (PNF) - Volume of wastewater per unit of production.

PSES - Pretreatment standards for existing sources of indirect discharges, under section 307(b)

of the Clean Water Act.

PSNS - Pretreatment standards for new sources of indirect discharges, under sections 307(b) and

(c) of the Clean Water Act.

RCRA - Resource Conservation and Recovery Act (PL 94-580) of 1976, as amended (42 U.S.C.

6901, et seq.).

SBREFA - Small Business Regulatory Enforcement Fairness Act of 1996 (P.L. 104-121,

March 29, 1996).

SGP - EPA’s National Metal Finishing Strategic Goals Program.

SIC - Standard Industrial Classification, a numerical categorization scheme used by the U.S.

Department of Commerce to denote segments of industry.
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Silica Gel Treated Hexane Extractable Material (SGT-HEM) - The freon-free oil and grease

method (EPA Method 1664) used to measure the portion of oil and grease that is similar to total

petroleum hydrocarbons. (Also referred to as nonpolar material (NPM)).

Site - A place of business that conducts MP&M operations (also referred to as “facility”).

SIU - Significant Industrial User. All industrial users subject to Categorical Pretreatment

Standards under 40 CFR 403.6 and 40 CFR Chapter I, subchapter N, and any other industrial

user that: discharges an average of 25,000 gallons per day or more of process wastewater to the

POTW (excluding sanitary, noncontact cooling, and boiler blowdown wastewater); contributes a

process wastestream that makes up 5 percent or more of the average dry weather hydraulic or

organic capacity of the POTW treatment plant; or is designated as such by the control authority

as defined in 40 CFR 403.12(a) on the basis that the industrial user has a reasonable potential for

adversely affecting the POTW’s operation or for violating any pretreatment standard or

requirement (in accordance with 40 CFR 403.8(f)(6)).

Source Reduction - Any practice that reduces the amount of any hazardous substance, pollutant,

or contaminant entering any waste stream or otherwise released into the environment prior to

recycling, treatment, or disposal. Source reduction can include equipment or technology

modifications, process or procedure modifications, substitution of raw materials, and

improvements in housekeeping, maintenance, training, or inventory control.

Surface Waters - Waters including, but not limited to, oceans and all interstate and intrastate

lakes, rivers, streams, mudflats, sand flats, wetlands, sloughs, prairie potholes, wet meadows,

playa lakes, and natural ponds.

Semivolatile Organic Compound (SVOC) - A measure of semivolatile organic constituents

performed by isotope dilution gas chromatography/mass spectrometry (GC/MS), EPA Method

1625. The isotope dilution technique uses stable, isotopically labeled analogs of the compounds

of interest as internal standards in the analysis.

Technical Development Document (TDD) - Development Document for the Proposed Effluent

Limitations Guidelines and Standards for the Metal Products & Machinery Point Source

Category.

Technology in Place (TIP) - Refers to those technologies that the Agency considered to be

installed and operating at a model site in 1989 (for Phase I questionnaire recipients) or 1996 (for

Phase II questionnaire recipients).

Total Annualized Cost (TAC) - Cost calculated from the capital and annual costs assuming a 7

percent discount rate over an estimated 15-year equipment life.

Total Organic Carbon (TOC) - A nonconventional bulk parameter that measures the total

organic content of wastewater (EPA Method 415.1). Unlike five-day biochemical oxygen
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demand (BOD5) or chemical oxygen demand (COD), TOC is independent of the oxidation state

of the organic matter and does not measure other organically bound elements, such as nitrogen

and hydrogen, and inorganics that can contribute to the oxygen demand measured by BOD5 and

COD. TOC methods utilize heat and oxygen, ultraviolet irradiation, chemical oxidants, or

combinations of these oxidants to convert organic carbon to carbon dioxide (CO2). The CO2 is

then measured by various methods.

Total Organics Parameter (TOP) - A parameter that is calculated as the sum of all quantifiable

concentration values greater than the nominal quantitation value of the organic pollutants listed

in the Appendix B to 40 CFR Part 438. These organic chemicals are defined as parameters at 40

CFR 136.3 in Table 1C, which also cites the approved methods of analysis or have procedures

that have been validated as attachments to EPA Methods 1624/624 or 1625/625.

Total Capital Investment (TCI) - Total one-time capital costs required to build a treatment

system (i.e., sum of direct and indirect capital costs).

Total Petroleum Hydrocarbons (TPH) - A method-defined parameter that measures the

presence of mineral oils that are extractable in Freon 113 (1,1,2-trichloro-1,2,2-trifluoroethane)

and not absorbed by silica gel. The analytical method for TPH and oil and grease has been

revised to allow for the use of normal hexane in place of Freon 113, a chlorofluorocarbon (CFC). 

Method 1664 (Hexane Extractable Material) replaces the current oil and grease Method 413.1

found in 40 CFR 136. (Also referred to as nonpolar material (NPM)).

Treatment Effectiveness Concentration - Treated effluent pollutant concentration that can be

achieved by each treatment technology that is part of an MP&M regulatory option.

Treatment, Storage, and Disposal Facility (TSDF) - A facility that treats, stores, or disposes of

hazardous waste in compliance with the applicable standards and permit requirements set forth

in 40 CFR Parts 264, 265, 266, and 270.

TRI - Toxic Release Inventory.

TSCA - Toxic Substances Control Act (15 U.S.C. 2601 et seq.).

TSS - Total suspended solids. A measure of the amount of particulate matter that is suspended

in a water sample, obtained by filtering a water sample of known volume. The particulate

material retained on the filter is then dried and weighed (see Method 160.2).

TTO - Total toxic organics, as defined in the Metal Finishing effluent guidelines (40 CFR

Part 433).

TWF - Toxic weighting factor. A factor developed for various pollutants using a combination of

toxicity data on human health and aquatic life and relative to the toxicity of copper. EPA uses 
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toxic weighting factors in determining the amount of toxicity that a pollutant may exert on

human health and aquatic life.

U.S.C. - The United States Code.

Unit Operations - All processes performed on metal parts, products, or machines in their

manufacture, maintenance, or rebuilding.

Variability Factor - A variability factor is used in calculating a limitation to allow for

reasonable, normal variation in pollutant concentrations when processed through well designed

and operated treatment systems. Variability factors account for normal fluctuations in treatment. 

By accounting for these reasonable excursions about the long-term average, EPA’s use of

variability factors results in limitations that are generally well above the actual long-term

average. 

Volatile Organic Compound (VOC) - A measure of volatile organic constituents performed by

isotope dilution gas chromatography/mass spectrometry (GC/MS), EPA Method 1624. The

isotope dilution technique uses stable, isotopically labeled analogs of the compounds of interest

as internal standards in the analysis.

Wet Air Pollution or Odor Pollution Control System Scrubbers - Any equipment using water

or water mixtures to control emissions of dust, odors, volatiles, sprays, or other pollutants.

Zero Discharger - A facility that does not discharge pollutants to waters of the United States or

to a POTW. Also included in this definition are discharge or disposal of pollutants by way of

evaporation, deep-well injection, off-site transfer to a treatment facility, and land application.