### FACT SHEET FOR NPDES PERMIT WA-002277-2
SOUTHWEST SUBURAN SEWER DISTRICT
SALMON CREEK WASTEWATER TREATMENT PLANT

Summary

• The monitoring frequency for both BOD 5 and TSS was increased from 1/week to 2/week to comply more closely with the guideline of 3/week as written in the Department’s Permit Writer’s Manual and to align with the facility’s actu al sample frequency during the previous permit cycle.

• Mixing Zone remained the same as in previous permit.

• Mass discharge limitations for BOD 5 and TSS remained the same from the previous permit.

• The design criteria for the facility (reference Ta ble 7) were corrected to match most recent Engineering Report approved by the Department of Ecology. Reference the 1985 Secondary Treatment Project Engineering Report by Pool Engineering, Incorporated.

• Acute WET limit was removed from perm it based on previous permit results.

• Waste characterization, according to the NPDES a pplication Part D requirements, is due in the fourth year of the permit cycle in order to provide information on compliance with human health criteria for the future permit. Refer to Appendix D for a complete list of these testing requirements.

• The Department requires that the Operations and Maintenance Manual be reviewed and updated within two (2) years of permit issuance.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

DRAFT TABLE OF CONTENTS

INTRODUCTION ................................................................................................................... ........4

BACKGROUND INFORMATION ................................................................................................6 DESCRIPTION OF THE FACILITY .................................................................................6 History......................................................................................................................6 Collection System Status .........................................................................................7 Treatment Processes.................................................................................................8 Discharge Outfall.....................................................................................................9 Residual Solids.........................................................................................................9 PERMIT STATUS.............................................................................................................11 SUMMARY OF COMPLIANCE WITH THE PREVIOUS PERMIT .............................11 WASTEWATER CHARACTERIZATION ......................................................................12 DMR 5-Year Summary..........................................................................................12 Priority Pollutants ..................................................................................................15 Whole Effluent Toxicity Testing ...........................................................................15

PROPOSED PERMIT LIMITATIONS.........................................................................................17 DESIGN CRITERIA .........................................................................................................17 TECHNOLOGY-BASED EFFL UENT LIMITATIONS..................................................18 SURFACE WATER QUALITY-BASE D EFFLUENT LIMITATIONS .........................19 Numerical Criteria for the Pr otection of Aquatic Life...........................................19 Numerical Criteria for the Pr otection of Human Health........................................19 Narrative Criteria ...................................................................................................19 Antidegradation......................................................................................................20 Critical Conditions.................................................................................................20 Mixing Zones.........................................................................................................20 Description of the Receiving Water.......................................................................20 Surface Water Quality Criteria ..............................................................................21 Consideration of Surface Wa ter Quality-based Limits for Numeric Criteria........21 Whole Effluent Toxicity ........................................................................................23 Human Health ........................................................................................................24 Sediment Quality ...................................................................................................25 GROUND WATER QUALITY LIMITATIONS..............................................................25 COMPARISON OF EFFLUENT LIMITS WITH THE EXISTING PERMIT ISSUED JUNE 23, 1997........................................................................................25

MONITORING REQUIREMENTS..............................................................................................26 LAB ACCREDITATION ..................................................................................................26

OTHER PERMIT CONDITIONS .................................................................................................27 REPORTING AND RECORDKEEPING .........................................................................27 PREVENTION OF FACILITY OVERLOADING...........................................................27 OPERATIONS AND MAINTENANCE (O&M) .............................................................27 RESIDUAL SOLIDS HANDLING...................................................................................27 PRETREATMENT............................................................................................................27FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

DRAFT Federal and State Pretreatme nt Program Requirements ....................................................27 Wastewater Permit Required .............................................................................................28 Requirements for Routine Identification and Reporting of Industrial Users.....................28 Annual Submittal of List of Industrial Users.....................................................................29 Duty to Enforce Discharge Prohibitions............................................................................29 Support by the Department for Developi ng Partial Pretreatment Program by POTW ....................................................................................................................29 GENERAL CONDITIONS ...............................................................................................29

PERMIT ISSUANCE PROCEDURES .........................................................................................30 PERMIT MODIFICATIONS ............................................................................................30 RECOMMENDATION FOR PERMIT ISSUANCE ........................................................30

REFERENCES FOR TEXT AND APPENDICES........................................................................31

APPENDIX A—PUBLIC INVOLVEMENT INFORMATION...................................................32

APPENDIX B—GLOSSARY.......................................................................................................33

APPENDIX C—TECHNICAL CALCULATIONS......................................................................38

APPENDIX D—EPA NPDES APPLICATION (PART D) TESTING REQUIREMENTS ........39

APPENDIX E—RESPONSE TO COMMENTS ..........................................................................40FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 4 INTRODUCTION The Federal Clean Water Act (FCWA, 1972, and later modifications, 1977, 1981, and 1987) established water quality goals for the navigable (sur face) waters of the United States. One of the mechanisms for achieving the goals of the Clean Water Act is the National Pollutant Discharge Elimination System of permits (NPDES permits), which is administered by the Environmental Protection Agency (EPA). The EPA has delegate d responsibility to administer the NPDES permit program to the State of Washingt on on the basis of chapter 90.48 RC W which defines the Department of Ecology's authority and obligations in administer ing the wastewater discha rge permit program. The regulations adopted by the Stat e include procedures for issui ng permits (chapter 173-220 WAC), technical criteria for discharges from municipal wastewater tr eatment facilities (chapter 173-221 WAC), water quality criteria for surface and gr ound waters (chapters 173-201A and 200 WAC), and sediment management standards (c hapter 173-204 WAC). These regula tions require that a permit be issued before discharge of wastewater to waters of the state is allowe d. The regulations also establish the basis for effluent lim itations and other requirements which are to be included in the permit. One of the requirements (WAC 173-220- 060) for issuing a permit under the NPDES permit program is the preparation of a draft permit and an accompanying fact sheet. Public notice of the availability of the draft permit is required at least thirty (30) days before the permit is issued (WAC 173-220-050). The fact sheet and draft permit ar e available for review (see Appendix A—Public Involvement of the fact sheet for more detail on the public notice procedures).
The fact sheet and draft permit have been revi ewed by the Permittee. Errors and omissions identified in this review have been corrected before going to public no tice. After the public comment period has closed, the Department will summarize the substantive comments and the response to each comment. The summary and respons e to comments will become part of the file on the permit and parties submitting comments will rece ive a copy of the Department's response. The fact sheet will not be revised. Comments and the resultant changes to the permit will be summarized in Appendix D—Response to Comments

.

GENERAL INFORMATION Applicant Information: Southw est Suburban Sewer District 431 Ambaum Boulevard SW Burien, WA 98166 Contact Person: William T. Skahan, General Manager (206) 244-9575 Facility Name and Address: Salmon Creek Wastewater Treatment Plant 12550 Shorewood Drive SW Burien, WA 98146 Facility Contact: Tim Berge, Senior Operator (206) 243-7770 Type of Treatment: Secondary Biological Treatment – Rotating Biological Contactors Discharge Location: Puget Sound – East Passage Latitude: 47o 29' 14" N Longitude: 122o 22' 04" W Water Body ID Number: WA-PS-0270FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 5 Figure 1 : Vicinity map showing location of Salmon Creek WWTP in Burien, WAFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 6 Figure 2: Facility Layout - Salmon Creek WWTP and Effluent Discharge Pipe to Puget Sound

BACKGROUND INFORMATION

DESCRIPTION OF THE FACILITY

Salmon Creek Wastewater Treatment Plant (WWTP) provides secondary treatment to wastewater using rotating bi ological contactors (RBC). Th e treatment pr ocess purifies wastewater to meet water quality regula tions before discharging into Puget Sound.

H ISTORY
Salmon Creek WWTP is operated by Southwest Suburban Sewer District (SWSSD) which was established in 1945 to serve the region of southw est King County. The original plant was built in 1955. The secondary treatment system using RBC technology was inst alled in 1989, and odor control and scrubbing system became operational in 1991. Additional upgrades occurred in 1998 with the addition of an Anoxic Gas Floatation (AGF) tank and Pasteuriza tion Tank to the sludge handling system. The AGF and Pasteurization Tanks were taken out of service in late 2002 and there are no plans to resume ope ration at this time. In 2002, the headworks were improved with the addition of 1⁄4-inch fine step screens. Screen ings were removed and disposed of in a landfill.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 7 It currently serves a population of 27,126 in the communities of White Center, Shorewood, Fauntleroy, Arbor Heights, Delridge, Highland Park, Seahurst, and Burien. 1 The service area is mostly residential with little i ndustrial or commercial activity. The facility lists no industrial discharges to the sewer system at this time. Salmon Creek WWTP is an EPA designated major facility.

C OLLECTION S YSTEM S TATUS
The Salmon Creek drainage basin is approximately 3350 acres. The collector/interceptor system includes 129 miles of piping ranging from 4 inches to 36 inches in diameter. 2 Portions of the collection system date to the 1940’s. SWSSD has 11 pump stati ons of which 5 pump to Salmon Creek WWTP. Pump capacity has been deemed sufficient and adequately designed as outlined in the Comprehensive Sewer Plan 1999 (“CSP”). 3

The CSP details flow projections in SWSSD over th e next nearly twenty years based on expected demographic changes in the di strict. CSP projects Salmon Creek WWTP to see a flow (mean annual, MGD) increase of approximately 14.6% from basis year 1996 to year 2020. 4 Plant improvements in 2002 and other continuous im provement projects will accommodate the anticipated flows.

The CSP used flow data from 1991 to 1996 to evalua te inflow and infiltration (I/I) attributed to direct storm runoff. I/I flow for Salmon Creek basin is 48% which equates to 1.72 gallons per day per foot of sewer line. 5 The District has applied for a nd received Public Works Trust Fund (PWTF) approval for a major rehabilitation pr ogram for the Salmon Creek basin. A list of collection system rehabil itation projects has been identified in the CSP to address I/I. Salmon Creek WWTP does not have a combined sewer overflow (CSO).

1 NPDES Permit Application.
2 Horton, Dennis and Associates, Kirk land, WA, Southwest Suburban Sewer District, 1999 Comprehensive Sewer

Plan, February 1999, p. 48.
3 Horton, CSP , p. 68.
4 Horton, CSP , p. 50.
5 Horton, CSP , p. 42.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 8 T REATMENT P ROCESSES

Figure 3. Process Flow Diagram – Salmon Creek WWTP 6

Refer to Figure 3. The plant wastewater influent enters the facility vi a a main truck line and several inverted siphon lines. The headworks include 1⁄4-inch fine step scr eens and grit collectors to remove debris from the wastewater. The debr is is washed and compacted in preparation for disposal at a landfill. The wastewater flows from the headworks to the primary clarifiers. The facility operates two or all three clarifiers depending on total flow of wastewater requiring treatment. Secondary treatment is done usi ng rotating biological cont actor (RBC) technology. There are three RBC trains; each train has seven shafts for a total of twenty-one air-driven rotating shafts. The wastewater flows from the RBCs to the secondary clarifiers. As with the primary clarifiers, the facility is able to operate with one se condary clarifier on line during low

6 NPDES Permit ApplicationFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 9 flow conditions. Disinfection is the final treatment step for the wastewater overflowing from the secondary clarifiers. Sodium Hypochlorite is inj ected into the wastewater just upstream of the contact tanks. The contact ta nks allow sufficient residence time for disinfection of the plant effluent prior to disc harge into Puget Sound.

Sludge handling is discussed under the section titled “Residual Solids.”

The Permittee lists no industrial users in the permit application and has not received any industrial wastewater duri ng the previous permit. It does no t foresee receiving any industrial wastewater during this permit cycle.

Salmon Creek WWTP is designated as a Cla ss 3 WWTP under State ope rator certification regulations, WAC 173-230. The permit requires that the sewage treatment plant operator in charge of operations be Class 3 certified. The plant is staffed by four operators in a 10-hour daily shift. The plant is staffed seven days per week.

Emergency operating procedures are adequately outlined in the Operations and Maintenance Manual , and all operators are appropriat ely trained in those procedures.

Improvement plans for 2002 and 2003 are funded by a loan from the Public Works Trust Fund. The plans for 2002 include improvements to screen ing of and grit removal from the wastewater.

D ISCHARGE O UTFALL
The treated and disinfected secondary effluent is discharged from the facility via the effluent pipe into Puget Sound. The existing outfall pipe was installed in 1969. It consists of 1200 lineal feet (lf) of 36-inch diameter c oncrete pipe underwater and 1580 lf of 36-inch concrete pipe to the facility for a total of 2780 lf of pipe. The out fall has a 100 lf multiple port diffuser assembly which has twelve discharge ports, the deepest di scharging at -200 feet mean lower low water (MLLW). 7 The CSP indicates that the dilution rate is adequate for current and future conditions based on the existing water quality standards. According to the CSP, the facility plans to continue to periodically monitor the condition of the outfall pipe for signs of deterioration. The last video inspection of the outfall was done in July 1995.

R ESIDUAL S OLIDS
Refer to Figure 3. The treatment facility rem oves solids during the treatme nt of the wastewater at the headworks (grit and screenings), and at th e primary and secondary cl arifiers, in addition to incidental solids (rags, scum, and other debris) removed as part of the routine maintenance of the equipment. Grit, rags, scum, and screenings are drained and disposed of as solid waste at the local landfill.

7 Gary R. Bourne, P.E., Poole Engineering, Inc., Secondary Treatment Project Engineering Report , August 1985, p. 7-7.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 10 Solids removed from the primary and secondary cl arifiers are treated first by pumping to a gravity thickener to increase the percent of solids and thereby improve filterability of the solids. The sludge is pumped to a primary anaerobic mes ophilic digester. The digested sludge is dewatered using a Parkson ® belt filter press. All the filtrate and other liquid waste streams from the facility are returned to the headworks for treatment.

The solids collected from the belt filter are truc ked batchwise to the District’s Miller Creek WWTP. The majority of the filter solids (C lass B biosolids) are land applied under permit number BA-002277-2. In addition, a portion of the dewatered biosolids are mixed with tree chippings and composted in aerat ed static piles for Class A biosolids which are screened and sold to the public. 8

The monitoring results for pollutant metals in sludge as required by 40 CFR 503 are shown in Table 1. The sludge generated at the facility m eets the exceptional quality standards set forth by federal regulations. Table 1. Biosolids Pollutant Concentrations (mg/kg)

Pollutant Analytical Method DL11-Jan-0011-Apr-0011-Jul-0017-Oct-0024-Jan-0126-Jul-0118-Oct-01 Ave. Standard

Arsenic SW-846 7060A 0.1 6.1 3.8 4 5.8 0.3 1.6 2 3.4 41

Cadmium SW-846 6010 0.05 1.8 2.9 6.9 1.6 3.9 2.7 3.4 3.3 39

Chromium SW-846 6010 0.1 18 14 28 19 18 20 24 20

Copper SW-846 6010 0.1 430 430 560 420 380 410 360 427 1500

Lead SW-846 6010 1 81 74 81 55 72 54 71 70 300

Mercury SW-84 7471A 0.01 0.5 0.76 2 1.4 1.2 1.3 1.4 1.2 17

Molybdenum SW-846 6010 0.5 4.6 6.1 9.8 7.1 3.8 5.3 5.7 6.1 18

Nickel SW-846 6010 0.5 20 15 30 13 18 19 16 19 420

Selenium SW-846 7740 0.1 1.4 5.6 4.1 2 4.8 0.1 2.4 2.9 100

Zinc SW-846 6010 0.1 1200 1000 1200 910 1000 1100 790 1029 2800

TolsI Kjel. N EPA 351.3 5 62500 56500 40700 58100 61000 67000 52000 56829

Ammonia SM 4500NH3 5 16300 15300 12900 13800 16000 15000 13000 14614

N02+N03 EPA 351.2 0.05 2.5 3.2 1 2.5 0.3 0.3 3.1 1.8

8 NPDES Form 2S Application OverviewFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 11 PERMIT STATUS

The previous permit for this facility was i ssued on June 23, 1997, and became effective on July 1, 1997. The previous permit placed effluent limitations on 5-day Biochemical Oxygen Demand (BOD 5 ), Total Suspended Solids (TSS), pH, F ecal Coliform bacteria, and Total Residual Chlorine (TRC).
An application for permit renewal was submitted to the Department on April 4, 2002, and accepted by the Department on April 29, 2002. An ex tension of the previous permit was granted as of June 23, 2002, and will remain in effect until the effective date of this permit.
Table 2. Previous Permit Limits

EFFLUENT LIMITATIONS a : OUTFALL # 001
Parameter Average Monthly Average Weekly Biochemical Oxygen Demand b (5-day) 30 mg/L, 2025 lb/day 45 mg/L, 3040 lb/day Total Suspended Solids b 30 mg/L, 2025 lb/day 45 mg/L, 3040 lb/day
Fecal Coliform Bacteria 200 cfu /100 mL 400 cfu /100 mL pH shall not be outside the range 6.0 to 9.0 Total Residual Chlorine 0.5 mg/L, 33.8 lb/day 0.75 mg/L Acute Whole Effluent Toxicity No statistical ly significant difference in survival between the control (0% effluent) and the ACEC of 0.625%.

a The average monthly and weekly effluent limitations are based on the arithmetic mean of the samples

taken with the exception of fecal coliform, which is based on the geometric mean.

b The average monthly effluent concentration for BOD 5 and Total Suspended Solids shall not exceed 30

mg/L or 15 percent of the respective monthly aver age influent concentrations, whichever is more stringent.

SUMMARY OF COMPLIANCE WITH THE PREVIOUS PERMIT Salmon Creek WWTP received two (2) Class I inspect ions by the Department during the previous permit on the dates of June 26, 1998, and May 3, 2001. The last inspection show ed the facility to be in good order. The inspector r ecommended that staffing should be re viewed to ensure that it is adequate based on EPA criteria. 9
During the history of the previous permit, the Permittee has remained in good compliance, based on Discharge Monitoring Reports (DMRs) submitted to the Department and inspections conducted by the Department. All reported efflue nt and influent data were reviewed for the 5-year period from July 1997 to July 2002. Tw o (2) violations occurred during the 5-year period. The first violation occurred in Oct ober 1997 when the pH was below 6.0. The second violation occurred in September 1998 when the BOD exceeded 30 mg/L. An additional compliance-related concern occurred in 1997 and 1998 when the facility exceeded 85% of the design criteria for BOD and TSS fo r three (3) consecutive months. This may indicate that the facility needs to inve stigate the need for e xpansion. The 1999 CSP addresses this concern.

9 Water Compliance Inspection Report, 5/3/02, Ed AbassiFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 12 Refer to Table 3: 5-Year Summary of Noncom pliance. A complete 5-year summary of DMR data is listed in Appendix C. Table 2: Su mmary of DMR Effluent Da ta and Summary of DMR Influent Data.
Table 3: Compliance History July 1997 to July 2002

Date Parameter Limit Reported Value Comment

Oct.-1997 Effluent pH 6.0 5.9 Sept.-1998 Fecal Coliform, monthly average 200 cfu/100 mL 241 Temperature related nitrification problems resulted in higher than normal chlorine demand. Disinfection pump delivered only 1⁄2 of rated capacity. Venturi injection was installed to accommodate high chlorine demand situations. 10 July-1997

Aug.-1997

Sept.-1997 Influent Flow exceeded 85% of design BOD and TSS loading for three (3) consecutive months. 7650 lb/day average for BOD and TSS 12338 BOD, 13264 TSS 9985 BOD, 10425 TSS 10411 BOD, 11423 TSS Due in part to influent sampling related problem which the facility is working to resolve.

Aug.-1998

Sept.-1998

Oct.-1998 Influent Flow exceeded 85% of design BOD loading for three (3) consecutive months. 7650 lb/day average for BOD 8256 BOD

8567 BOD

8237 BOD Due in part to influent sampling related problem which the facility is working to resolve.

WASTEWATER CHARACTERIZATION

DMR 5-Y EAR S UMMARY
The concentration of pollutants in the discharge was reported in the NPDES application and in Discharge Monitoring Reports. Th e effluent is characterized as follows, as summarized from Discharge Monitoring Report Data (Appendix C):

10 Discharge Monitor Report Salmon Creek, September 1998.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 13 Table 4: Wastewater Characterization (5-year Summary)

Pollutant/ Analysis Units Design Criteria Permit Limit or 85% of Design* 5-yr. Average Minimum Maximum

BOD, 5 LB/DAY AVG 2025 255.6 98 744 BOD, 5 LB/DAY AVW 3040 351.5 151.0 1303.0 BOD, 5 MG/L AVG 30 11.3 5.9 21.3 BOD, 5 MG/L AVW 45 14.1 7.1 24.6 BOD, 5 % PERCENT AVG 85 96.3 87.0 99.0
CL LB/DAY AVG 33.8 5.6 2.8 15.3
CL MG/L AVG 0.5 0.3 0.15 0.43
CL MG/L MAX 0.75 0.3 0 0
COLI. FECAL #/100 ML GEM 200 28.0 4 241
COLI. FECAL #/100 ML GM7 400 59.8 6.0 352.0 FLOW, IN MGD AVG 8.1 6.89* 2.6 1.9 4.8 FLOW, IN MGD MAX NA 3.9 2.11 9.70
PH S.U. MAX 9 7.3 6.8 7.9
PH S.U. MIN 6 6.6 5.9 7.0
TSS % PERCENT AVG 85 96.6 91.0 99.0
TSS LB/DAY AVG 2025 176.0 69 483
TSS LB/DAY AVW 3040 229.2 80 691
TSS MG/L AVG 30 7.7 4.2 13.4
TSS MG/L AVW 45 9.2 4.7 17.9FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 14 Salmon Creek 5-year Organic Loading

0 2000 4000 6000 8000 10000 12000 14000

1 - J u l - 9 7

1 - O c t - 9 7

1 - J a n -9 8

1 - A p r - 9 8

1 - J u l - 9 8

1 - O c t - 9 8

1 - J a n -9 9

1 - A p r - 9 9

1 - J u l - 9 9

1 - O c t - 9 9

1 - J a n -0 0

1 - A p r - 0 0

1 - J u l - 0 0

1 - O c t - 0 0

1 - J a n -0 1

1 - A p r - 0 1

1 - J u l - 0 1

1 - O c t - 0 1

1 - J a n -0 2

1 - A p r - 0 2

Day/Yearloading (lb/day)

BOD (lb/day) TSS (lb/day) Design TSS Loading (lb/day) Design BOD Loading (lb/day) Permit BOD and TSS loadin g = 9,200 lb/da y

Salmon Creek 5-year Hydraulic Loading

0 2 4 6 8 10 12

1

- J u l - 9 7

1 - O

c t - 9 7

1

- J a n - 9 8

1 - A p r - 9 8

1 - J u l - 9 8

1 - O

c t - 9 8

1 - J a n - 9 9

1 - A p r - 9 9

1 - J u l - 9 9

1 - O

c t - 9 9

1

- J a n - 0 0

1 - A p r - 0 0

1 - J u l - 0 0

1 - O

c t - 0 0

1 - J a n - 0 1

1

- A p r - 0 1

1 - J u l - 0 1

1

- O

c t - 0 1

1

- J a n - 0 2

1 - A p r - 0 2

Date/YearFlow (GMD)

Max. Monthly Ave. Daily Flow Ave. Daily Flow Average Flow Max. Month Permit Design Criteria = 8.1 MGD

Figure 4: Salmon Creek Organic and Hy draulic Loading January 1997 to January 2002 vs. Approved Design CriteriaFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 15 Hydraulic loading has remained consistent over th e term of the pervious permit. The organics and solids loading have remained within the design limits of this permit with the exception of a few explained excursions (reference Table 3). Both of the above graphs display the Permittees ability to operate the facility within the design criteria upon which this permit is based.

P RIORITY P OLLUTANTS
The Permittee characterized the effluent for priority pollutant metals during the last permit cycle. The data was analyzed to determine if there is a reasonable potential to vi olate state water quality standards for any of the pollutant s listed in Table 5. Calculati ons for Reasonable Potential are shown in Appendix C, Table 5. Based on these ca lculations, none of the pollutants listed below have a reasonable potential to exceed water quality standards. Table 5: Priority Pollutants Analysis (all units in mg/l)

Parameter Method DL 5/31/2001 8/29/2001 10/18/2001 1/29/2002 Average Antimony 200.7 0.01 0.01 0.02 0.01 0.01 <0.0125
Arsenic 206.2 0.001 0.001 0.001 0.001 0.001 0.001 Beryllium 200.7 0.0005 0.0005 0.0005 0.0005 0.0005 <0.00005
Cadmium 200.7 0.0005 0.0005 0.0005 0.0005 0.0005 <0.0005
Chromium 200.7 0.001 0.001 0.001 0.001 0.002 <0.00125 Copper 200.7 0.001 0.003 0.015 0.013 0.005 0.009
Lead 239.2 0.001 0.001 0.001 0.016 0.001 0.00475 Mercury 245.1 0.0002 0.0002 0.0002 0.0002 0.0002 <0.0002
Nickel 200.7 0.005 0.005 0.005 0.005 0.005 <0.005
Selenium 270.2 0.001 0.001 0.001 0.001 0.002 <0.00125
Silver 200.7 0.01 0.01 0.01 0.01 0.01 <0.01
Thallium 279.2 0.001 0.001 0.001 0.001 0.001 <0.001
Zinc 200.7 0.001 0.037 0.05 0.054 0.035 0.044
italics – Indicates pollutant found in a detectable quantity in effluent. bold – Indicates maximum effluent concen tration measured for pollutants found in a detectable quantity.

W HOLE E FFLUENT T OXICITY T ESTING
The Permittee performed two (2) chronic Whole E ffluent Toxicity (WET) tests for the purpose of characterization of the effl uent in August 2000 and March 2001 as required by the previous permit. They performed nine (9) acute WET tests at the rate of one test every six (6) months as required by the previous permit. The results of these tests are shown in Table 6. The WET tests results were reviewed by the Department’s WET Coordinator who concluded that no WET limits are required in this permit. The Permitt ee is required to perform WET testing for characterization purposes at the times specified in the permit Sections S8 and S9 of this permit.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 16 Table 6: Whole Effluent Toxicity (WET) Testing

Date Report Submitted Type of Test Sample Dates (24-hour composite samples) Summary of Results

Oct. 15, 1997 Acute September 3, 1997 Daphnia pulex LC50 = >100% Mar. 15, 1998 Acute February 9, 1998 Fathead minnow LC50 = >100% Sep. 15, 1998 Acute August 25, 1998 Daphnia pulex LC50 = >100% Mar. 15, 1999 Acute February 9, 1999 Fathead minnow LC50 = >100% Sept. 15, 1999 Acute August 9, 1999 Daphnia pulex LC50 = >100% Mar. 15, 2000 Acute February 15, 2000 Fathead minnow LC50 = >100% Aug. 15, 2000 Chronic July 10, 12, and 14, 2000 Topsme lt: Survival NOEC = 100% LOEC = >100% Growth NOEC = 100% LOEC = >100% Mysidopsis bahia: Survival NOEC = 50% LOEC = 100% Growth NOEC = 25% LOEC = 50% Aug. 15, 2000 Acute Jul 10, 2000 Daphnia pulex LC50 = >100% Mar. 15, 2001 Chronic Jan. 24, 26, and 29, 2001 Topsme lt: Survival NOEC = 100% LOEC = >100% Growth NOEC = 100% LOEC = >100% Mysidopsis bahia: Survival NOEC = 50% LOEC = 100% Growth NOEC = 25% LOEC = 50% Mar. 15, 2001 Acute Jan. 24, 2001 Fathead minnow NOEC = 100% LC50 = >100% Jan. 15, 2002 Acute December 12, 2001 Daphnia pulex: LC50 = >100%FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 17 PROPOSED PERMIT LIMITATIONS
Federal and state regulations requir e that effluent limitations set fo rth in an NPDES permit must be either technology- or water quali ty-based. Technology-based limitations for municipal discharges are set by regulation (40 CFR 133, and chapters 173-220 and 173-221 WAC). Water quality-based limitations are based upon compliance with the su rface water quality standards (chapter 173-201A WAC), ground water standards (cha pter 173-200 WAC), sediment qua lity standards (chapter 173- 204 WAC), or the National Toxics Rule (F ederal Register, Volu me 57, No. 246, Tuesday, December 22, 1992.) The most stringent of these t ypes of limits must be chosen for each of the parameters of concern. Each of these types of limits is described in more detail below.
The limits in this permit are based in part on info rmation received in the a pplication. The effluent constituents in the application were evaluated on a technology- and water quality-basis. The limits necessary to meet the rules a nd regulations of the State of Washington were determined and included in this permit. Ecology does not develop effluent limits for all pollutants that may be reported on the application as present in the effluent

. Some pollutants are not treatable at the concentrations reported, are not c ontrollable at the source, are not listed in regul ation, and do not have a reasonable potential to cause a water quality violation

. Effluent limits are not always developed for pollutants that may be in the discharg e but not reported as pres ent in the application. In those circumstances the permit does not author ize discharge of the non-reported pollutants. Effluent discharge conditions may change from th e conditions reported in th e permit application. If significant changes occur in any constituent, as described in 40 CFR 122.42(a), the Permittee is required to notify the Department of Ecology. The Permittee may be in violation of the permit until the permit is modified to reflect additional discharge of pollutants.

DESIGN CRITERIA In accordance with WAC 173-220-150 (1)(g), flows or waste loadings shall not exceed approved design criteria. The design criteria for this treatment facility are taken from the 1985 Secondary Treatment Project Engineering Report by P ool Engineering, Inc., and are as follows: Table 7: Design Standards for Salmon Creek WWTP 11

Criteria Design Year 2010 Design Year 2040 85% of Design Sewered Population 26,000 33,000 Flow (MGD) annual average 4.0 5.1 dry weather average 3.3 4.1 wet weather average 4.7 6.0 maximum month 6.4 8.1 6.89 maximum day 16.0 20.4 peak hour 20.0 25.5 Maximum flow to secondary 10.0 10.0 Loadings (pounds/day) BOD annual average 5,500 7,100 BOD maximum month 7,200 9,200 7,820 SS annual average 5,500 7,100 SS maximum month 7,200 9,200 7,820

11 Borne, p. 3-9FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 18 The design criteria listed in the previous permit was incorrect. The above table was updated to show the correct design criteria. The plant wa s designed for an ultimate maximum month flow of 8.1 MGD. When the flow reaches 6.4 MGD around the year 2010, the only necessary change will be to restage the RBCs by re moving the baffles between the 2 nd and 3 rd stages. As this is an operational change only, the design values in th e permit will be the 2040 va lues. Construction of additional facilities will be necessary when those loadings are approached.

TECHNOLOGY-BASED EFFLUENT LIMITATIONS Municipal wastewater treatment plants are a cat egory of discharger fo r which technology-based effluent limits have been promulgated by federal and state regulations. Th ese effluent limitations are given in the Code of Federal Regulations (CFR) 40 CFR Part 133 (fed eral) and in chapter 173-221 WAC (state). These regulations are perf ormance standards that constitute all known available and reasonable methods of preven tion, control, and treatment for municipal wastewater. The following technology-based limits for pH, fecal coliform, BOD 5 , and TSS are taken from chapter 173-221 WAC: Table 8: Technology-based Limits

Parameter Limit pH: shall be within the range of 6 to 9 standard units. Fecal Coliform Bacteria Monthly Geometric Mean = 200 organisms/100 mL Weekly Geometric Mean = 400 organisms/100 mL BOD 5 (concentration) Average Monthly Limit is the most stringent of the following: - 30 mg/L - may not exceed fifteen percent (15%) of the average influent concentration Average Weekly Limit = 45 mg/L TSS (concentration) Average Monthly Limit is the most stringent of the following: - 30 mg/L - may not exceed fifteen percent (15%) of the average influent concentration Average Weekly Limit = 45 mg/L Chlorine Average Monthly Limit = 0.5 mg/L Average Weekly Limit = 0.75 mg/L

The technology-based monthly average limitation for chlorine is derived from standard operating practices. The Water Pollution Control Federation's Chlorination of Wastewater (1976) states that a properly designed and maintained wast ewater treatment plant can achieve adequate disinfection if a 0.5 mg/lite r chlorine residual is maintained af ter fifteen minutes of contact time. See also Metcalf and Eddy, Wastewater Engi neering, Treatment, Disposal and Reuse , Third Edition, 1991. A treatment plant that provides ade quate chlorination contact time can meet the 0.5 mg/liter chlorine limit on a monthly average basis. According to WAC 173-221-030(11)(b), the corresponding weekly average is 0.75 mg/liter. The following technology-based mass limits are based on WAC 173-220-130(3)(b) and 173-221-030(11)(b).FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 19 For BOD 5 and TSS : Monthly effluent mass loadings (lb/day) were calculated as the maxi mum monthly design flow (8.1 MGD) x Concentration limit (30 mg/L) x 8.34 (conversion factor) = mass limit 2027 lb/day (rounded to 2025 lb/day for the permit limit). The weekly average effluent mass loading is cal culated as 1.5 x monthly loading = 3040 lb/day.

Chlorine : Monthly effluent mass loadings (lb/day) were calculated as the maxi mum monthly design flow (8.1 MGD) x Concentration limit (0.5 mg/L) x 8.34 (conversion factor) = mass limit 33.8 lb/day. The weekly average effluent mass loading is omitted. Maximum mass chlorine limits conflict with requirements to provide disinfection duri ng extremely high flow episodes. Such flow episodes have occurred at least once in each of the last two years. These rare events affect the weekly output more drastically than the monthly outputs.
SURFACE WATER QUALITY-BASED EFFLUENT LIMITATIONS In order to protect existing water quality and preserve the designated beneficial uses of Washington's surface waters, WAC 173-201A-060 stat es that waste discharge permits shall be conditioned such that the discharge will meet es tablished surface water quality standards. The Washington State surface water qua lity standards (chapter 173-201A WAC) is a state regulation designed to protect the beneficial uses of the su rface waters of the state. Water quality-based effluent limitations may be base d on an individual waste load allocation (WLA) or on a WLA developed during a basin-wide total maximum daily loading study (TMDL).

N UMERICAL C RITERIA FOR THE P ROTECTION OF A QUATIC L IFE "Numerical" water quality criteria are numerical va lues set forth in the Washington State’s water quality standards for surface waters (chapter 173-201A WAC). They specify the levels of pollutants allowed in receiving water while rema ining protective of aquatic life. Numerical criteria set forth in the water qu ality standards are used along with chemical and physical data for the wastewater and receiving wate r to derive the effluent limits in the discharge permit. When surface water quality-based limits are more stri ngent or potentially more stringent than technology-based limitations, they must be used in a permit.

N UMERICAL C RITERIA FOR THE P ROTECTION OF H UMAN H EALTH The state was issued 91 numeric water quality criter ia for the protection of human health by the U.S. EPA (EPA, 1992). These criteria ar e designed to protect humans from cancer and other diseases and are primarily applicable to fish and shellfish consumption and drinking water from surface waters.

N ARRATIVE C RITERIA

In addition to numerical criter ia, "narrative" water quality criteria (WAC 173-201A-030) limit toxic, radioactive, or deleterious material concentrations below t hose which have the potential to adversely affect characteristic water uses, cause acute or chronic toxicity to biota, impair aesthetic values, or adversely affect human h ealth. Narrative criteria protect th e specific beneficial uses of all fresh (WAC 173-201A-130) and marine (WAC 173-201A -140) waters in the state of Washington.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 20 A

NTIDEGRADATION The State of Washington's Antidegradation Policy requires that discharges into receiving water shall not further degrade the ex isting water quality of the water body. In cases where the natural conditions of receiving water are of lower quali ty than the criteria assigned, the natural conditions shall constitute the wa ter quality criteria. Similarly, when the natural conditions of receiving water are of higher qua lity than the criteria assigne d, the natural conditions shall constitute the water quality criteria. More information on the State Antidegradation Policy can be obtained by referri ng to WAC 173-201A-070. The Department has reviewed existing records and is unable to determ ine if ambient water quality is either higher or lower than the desi gnated classification crit eria given in chapter 173-201A WAC; therefore, the Department will use the designated classifica tion criteria for this water body in the proposed permit. The discharg es authorized by this proposed permit should not cause a loss of beneficial uses.

C RITICAL C ONDITIONS Surface water quality-based limits are derived for the water body's critical condition, which represents the receiving water and waste discharge condition with the highest potential for adverse impact on the aquatic bi ota, human health, and existi ng or characteristic water body

uses.

M IXING Z ONES The water quality standards allow the Departme nt of Ecology to authorize mixing zones around a point of discharge in establishi ng surface water quality-based effluent limits. Both "acute" and "chronic" mixing zones may be au thorized for pollutants that ca n have a toxic effect on the aquatic environment near the point of discharge. The concentration of pollutants at the boundary of these mixing zones may not exceed the numerical criteria for that type of zone. Mixing zones can only be authorized for discha rges that are receiving all kn own, available, and reasonable methods of prevention, control and treatment (AKART) and in accordance with other mixing zone requirements of WAC 173-201A-100.
The National Toxics Rule (EPA, 1992) allows the ch ronic mixing zone to be used to meet human health criteria.

D ESCRIPTION OF THE R ECEIVING W ATER The facility discharges to Puget Sound which is designated as a Class AA receiving water in the vicinity of the outfall. Characteristic uses include the following: water supply (domestic, industrial, agricultural) ; stock watering; fish migration; fish and shellfish rearing, spawning and harvesting; w ildlife habitat; primary contact recreation; sport fishing; boating and aesthetic enjoyment; commerce and navigation. Water quality of this class shall markedly and uniformly exceed the requirements for all or substantially all uses.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 21 S URFACE W ATER Q UALITY C RITERIA Applicable criteria are defined in chapter 173-20 1A WAC for aquatic biot a. In addition, U.S. EPA has promulgated human health criteria for toxic pollutants (EPA, 1992) . Criteria for this discharge are summarized below:

Fecal Coliforms 14 organisms/100 mL maximum geometric mean Dissolved Oxygen 7 mg/L minimum Temperature 13 degrees Celsius maximum or incr emental increases above background pH 7.0 to 8.5 standard units Turbidity Less than 5 NTUs above background Toxics No toxics in toxic amounts (see Appendi x C for numeric criteria for toxics of concern for this discharge)

C ONSIDERATION OF S URFACE W ATER Q UALITY -B ASED L IMITS FOR N UMERIC C RITERIA Pollutant concentrations in the proposed di scharge exceed water qua lity criteria with technology-based controls which the Department has determined to be AKART. A mixing zone is authorized in accordance with the geometri c configuration, flow restriction, and other restrictions for mixing zones in chapter 173-201A WAC. The regulation re quires that the mixing zone not extend in any horizontal direction from the discharge port for a distance greater than two hundred feet plus the depth of water over the discharge port. The depth of the outfall is 200 feet at MLLW. The dimensions of the mixing zone are shown in the diagram below.

Figure 5: Schematic diagram of the mixing zone. 100 foot long, 12 port diffuserFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 22 The Department has estimated dilution factors of effluent to receiving water that occur within these zones at the critical c onditions by the use of EPA PLUMES model, third edition, August 1995. Inputs for the model are taken from am bient data collected by Ecology at monitoring station EAP001 (East Passage) and ambient curren t data supplied by the National Oceanic Data Center for a station within one mile of the outfa ll. The estimated dilution factors are as follows:

Acute Chronic Aquatic Life 160 770 Human Health, Carcinogen NA 1225 Human Health, Non-carcinogen NA 1025
Pollutants in an effluent may affect the aqua tic environment near the point of discharge (near-field) or at a considerable di stance from the point of discharg e (far-field). Toxic pollutants, for example, are near-field pollutants—their adve rse effects diminish rapidly with mixing in the receiving water. Conversely, a pollutant such as BOD is a fa r-field pollutant whose adverse effect occurs away from the discharge even af ter dilution has occurred. Thus, the method of calculating water quality-based efflue nt limits varies with the point at which the pollutant has its maximum effect. The derivation of water quality-b ased limits also takes into a ccount the variability of the pollutant concentrations in both the effluent and the receiving water.

BOD 5 --Under critical conditions ther e is no predicted violation of the water quality standards for surface waters. Therefore, the techno logy-based effluent limitation for BOD 5 was placed in the permit.
Temperature --The impact of the discharge on the te mperature of the receiving water was modeled by simple mixing analysis at critical condition. The receiving water varies from 8 o C to 12.5 o C and the effluent temperature 10 o C to 20 o C. The discharge of 20 o C effluent into the marine water at 8 o C results in a temperature change of less than 0.1 o C. Under critical conditions there is no predicted violation of the water qua lity standards for surface waters. Therefore, no effluent limitation for temperature wa s placed in the proposed permit.
pH --Because of the high buffering capacity of marine water, compliance with the technology-based limits of 6 to 9 will assure comp liance with the water quality standard of 7 to 8.5 in the receiving water.

Fecal Coliform --The numbers of fecal coliform were modeled by simple mixing analysis using the technology-based limit of 400 organisms pe r 100 ml and a dilution factor of 770. The dilution reduces the bacteria to less than 1 ( 400/770). Under critical conditions there is no predicted violation of the wate r quality standards for surface wa ters with the technology-based limit. Therefore, the technology-based effluent li mitation for fecal coliform bacteria was placed in the proposed permit.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 23 Toxic Pollutants --Federal regulations (40 CFR 122.44) require NPDES permits to contain effluent limits for toxic chemicals in an efflue nt whenever there is a reasonable potential for those chemicals to exceed the surf ace water quality criteria. This process occurs concurrently with the derivation of technology-based effluent li mits. Facilities with technology-based effluent limits defined in regulation are not exempted from meeting the water quality standards for surface waters or from having surface water quality-based effluent limits. The following toxics were determined to be present in the discharge: chlorine, ammonia, and heavy metals, arsenic, copper, lead, and zinc . A reasonable potential analysis (see Appendix C, Table 5) was conducted on these parameters to dete rmine whether or not effluent limitations would be required in this permit.
The determination of the reasonable potential for the pollutants listed in the previous paragraph to exceed the water quality criteria was eval uated with procedures given in EPA, 1991 (Appendix C) using the acute a nd chronic dilution factors calc ulated for aquatic life. No valid ambient background data was available for above-listed pol lutants. A determination of reasonable potential using zero for backgr ound resulted in no reasonable potential. Water quality criteria for metals in chapter 173-201A WAC are based on the dissolved fraction of the metal. The Permittee may provide data clearly demonstra ting the seasonal partitioning of the dissolved metal in the ambient water in relation to an efflue nt discharge. Metals cr iteria may be adjusted on a site-specific basis when data is available clearly demonstra ting the seasonal partitioning in the ambient water in relation to an effluent discharge. Metals criteria may also be adjusted using th e water effects ratio ap proach established by USEPA, as generally guided by the procedur es in USEPA Water Quality Standards Handbook
, December 1983, as supplemented or replaced.

W HOLE E FFLUENT T OXICITY The water quality standards for surface waters requi re that the effluent not cause toxic effects in the receiving waters. Many toxic pollutants cann ot be detected by commonly available detection methods. However, toxicity can be measured directly by exposing liv ing organisms to the wastewater in laboratory tests and measuring the response of the organisms. Toxicity tests measure the aggregate toxicity of the whole efflue nt, and therefore this approach is called whole effluent toxicity (WET) testing. Some WET te sts measure acute toxicity and other WET tests measure chronic toxicity. Acute toxicity tests measure mortality as the signif icant response to the toxi city of the effluent. Dischargers who monitor their wast ewater with acute toxicity test s are providing an indication of the potential lethal effect of the effluent to organisms in the receiving environment. Chronic toxicity tests measure va rious sublethal toxic responses such as retarded growth or reduced reproduction. Chronic toxici ty tests often involve either a complete life cycle test of an organism with an extremely short life cycle or a pa rtial life cycle test on a cr itical stage of one of a test organism's life cycles. Orga nism survival is also measured in some chronic toxicity tests.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 24 Accredited WET testing laboratories have the pr oper WET testing protocols, data requirements, and reporting format. Accredite d laboratories are know ledgeable about WET testing and capable of calculating an NOEC, LC 50 , EC 50 , IC 25, etc. All accredited labs have been provided the most recent version of the Department of Ecology Publication # WQ-R-95-80, Laboratory Guidance and Whole Effluent Toxicity Test Review Criteria which is referenced in the permit. Any Permittee interested in receiving a copy of this publication may call the Ecology Publications Distribution Center (360-407-7472) for a copy. Ecology recommends that Permittees send a copy of the acute or chronic toxi city sections(s) of their permits to their laboratory of choice. The WET tests during effluent characterization indicate that no reasonable potential exists to cause receiving water acute toxicity , and the Permittee will not be given an acute WET limit and will only be required to retest the effluent pr ior to application for permit renewal in order to demonstrate that acute toxicity ha s not increased in the effluent. The WET tests during effluent characterization indicate that no reasonable potential exists to cause receiving water chronic toxicity , and the Permittee will not be given a chronic WET limit and will only be required to retest the effl uent prior to application for permit renewal in order to demonstrate that chronic toxic ity has not increase d in the effluent. If the Permittee makes process or material change s which, in the Department's opinion, results in an increased potential for effluent toxicity, then the Department may requi re additional effluent characterization in a regulatory or der, by permit modification, or in the permit renewal. Toxicity is assumed to have increased if WET testing c onducted for submission wi th a permit application fails to meet the performance standards in WAC 173-205-020, "whole effluent toxicity performance standard." The Permittee may demonstr ate to the Department that changes have not increased effluent toxicity by performing additi onal WET testing after the time the process or material changes have been made.

H UMAN H EALTH Washington’s water quality standards now include 91 numeric health-based criteria that must be considered in NPDES permits. These criteria we re promulgated for the state by the U.S. EPA in its National Toxics Rule (Federal Regist er, Volume 57, No. 246, Tuesday, December 22, 1992).
The Department has determined that the effluent is likely to have chemicals of concern for human health. The discharger's high priority status is based on: (1) the di scharger’s status as a major discharger, and (2) knowle dge of data or process info rmation indicating regulated chemicals occur in the discharge. A determination of the discharge's potential to cause an exceedance of the water quality standards was conducted as required by 40 CFR 122.44(d). The reasonable potential determination was evaluated with procedures given in the Technical Support Document for Water Quality-Based Toxics Control (E PA/505/2-90-001) and the Department's Permit Writer's Manual (Ecology Publication 92-109, July 2002). The determination indicate d that the discharge has no reasonable potential to cause a violation of water quality stan dards, thus an effluent limit is not warranted.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 25 S EDIMENT Q UALITY The Department has promulgated aquatic sediment standards (chapter 1 73-204 WAC) to protect aquatic biota and human health. These standa rds state that the Department may require Permittees to evaluate the potential for the discha rge to cause a violation of applicable standards (WAC 173-204-400). The Department has determined through a review of the discharger char acteristics and effluent characteristics that this discharge has a reasonab le potential to violate the sediment management standards for Arsenic, Copper, Lead and Zinc, Appendix C, Table 7: Potential for Sediment Contamination. However, the Permittee conducted a Sediment Baseline Analysis (February 1997) which showed no pattern of sediment contaminati on. No additional sediment analysis is required by this permit.
GROUND WATER QUALITY LIMITATIONS The Department has promulgated ground water quality standards (chapter 173-200 WAC) to protect uses of ground water. Permits issued by the Department shall be conditioned in such a manner so as not to allow violations of those standards (WAC 173-200-100). This Permittee has no discharge to ground and therefore no limitations are required based on potential effects to ground water.

COMPARISON OF EFFLUENT LIMITS WITH THE EXISTING PERMIT ISSUED JUNE 23, 1997

Parameter Existing Limits Proposed Limits

BOD 5 monthly average 30 mg/L, 2025 lb/day weekly maximum 45 mg/L, 3040 lb/day monthly average 30 mg/L, 2025 lb/day weekly maximum 45 mg/L, 3040 lb/day TSS monthly average 30 mg/L, 2025 lb/day weekly maximum 45 mg/L, 3040 lb/day monthly average 30 mg/L, 2025 lb/day weekly maximum 45 mg/L, 3040 lb/day pH Shall be within the range of 6 to 9 standard units Shall be within the range of 6 to 9 standard units Fecal Coliform Bacteria monthly average 200/100 mL weekly maximum 400/100 mL monthly average 200/100 mL weekly maximum 400/100 mL Total Residual Chlorine 0.5 mg/L monthly average 0.75 mg/L daily maximum 0.5 mg/L monthly average 0.75 mg/L daily maximum Acute WET Testing No statistically significant difference in survival between the control (0% effluent) and ACEC (0.625% effluent) NoneFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 26 MONITORING REQUIREMENTS
Monitoring, recording, and reporting are re quired (WAC 173-220-210 and 40 CFR 122.41) to verify that the treatment process is functioning correctly and the effluent limitations are being achieved. Monitoring of sludge quantity and qu ality is necessary to determine the appropriate uses of the sludge. Sludge monitoring is required by the cu rrent state and local solid waste management program and also by EPA under 40 CFR 503. The monitoring schedule is detailed in the proposed permit under Condition S.2. Specified monitoring frequencies take into account the quantity and variability of discharge, the treatment method, past compliance, significance of polluta nts, and cost of monitoring. The required monitoring frequency is consistent with agen cy guidance given in th e current version of Ecology’s Permit Writer's Manual (July 2002) for a rotating biol ogical contactor (RBC) facility of greater than 2 MGD desi gn with a partial reduction fo r exemplary performance. The reduced frequency is determined by the ratio of the long term average (LTA) to the average monthly limit (AML). The results of the an alysis as shown are based on the DMR data submitted for the 2-year period from June 2000 to July 2002 for both BOD and TSS.

Pollutant LTA (mg/L) AML (mg/L) Ratio (LTA/AML) Allowable Minimum Monitoring Frequency for Ratio 12 25%-49% <25% BOD 5 10.4 30 35% 1/week 1/week TSS 6.0 30 23% 1/week 1/week The monitoring requirement for both BOD 5 and TSS is set at 2/week . This determination was made based on: (1) that it is more comparable to the requirement for other facilities of similar design and flow and (2) that it a ligns with the sample frequenc y of the Permittee over the last year of the previous permit cycle.

LAB ACCREDITATION With the exception of certain parameters, the permit requires all monitoring data to be prepared by a laboratory registered or accredited unde r the provisions of chapter 173-50 WAC, Accreditation of Environmental Laboratories. The laboratory at this faci lity is accredited for: Biological Oxygen Demand, Total Suspended Solids, Fecal Coliform, Dissolved Oxygen and pH.

12 Ecology Permit Writer’s Manual , p. XIII-15.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 27 OTHER PERMIT CONDITIONS

REPORTING AND RECORDKEEPING

The conditions of S3 are based on the author ity to specify any a ppropriate reporting and recordkeeping requirements to prevent and control waste discharges (WAC 173-220-210).

PREVENTION OF FACILITY OVERLOADING Overloading of the treatment plant is a violation of the terms and conditions of the permit. To prevent this from occurring, RCW 90.48.110 a nd WAC 173-220-150 require the Permittee to take the actions detailed in propos ed permit requirement S.4 to plan expansions or modifications before existing capacity is reached and to report and correct conditions th at could result in new or increased discharges of pollutants. Condition S.4 restricts the amount of flow.
OPERATIONS AND MAINTENANCE (O&M) The proposed permit contains Condition S .5 as authorized under RCW 90.48.110, WAC 173-220-150, chapter 173-230 WAC, and WAC 173-240- 080. It is included to ensure proper operation and regular maintenance of equipment, and to ensure that adequate safeguards are taken so that constructed facilities are used to their optimum potential in terms of pollutant capture and treatment. The Departme nt requires the Permittee to update the Operations and Maintenance Manual (current version 1988) to ensure that it provides accura te and up-to-date information.

RESIDUAL SOLIDS HANDLING To prevent water quality problems, the Permittee is required in permit Condition S7 to store and handle all residual solids (grit, screenings, scum, sludge, and other solid waste) in accordance with the requirements of RCW 90.48.080 and state water quality standards. The final use and disposal of sewage sludge from this facility is regu lated by U.S. EPA under 40 CFR 503. The disposal of other solid waste is under the jurisdiction of the King County Health Department.

PRETREATMENT

Federal and State Pretreat ment Program Requirements

Under the terms of the addendum to the “Mem orandum of Understand ing between Washington Department of Ecology and the United States Environmental Protection Agency, Region 10” (1986), the Department of Ecology (Department) ha s been delegated author ity to administer the Pretreatment Program [i.e., act as th e Approval Authority for oversight of delegated Publicly Owned Treatment Works (POTWs)]

. Under this delegation of authority, the Department has exercised the option of issuing wastewater di scharge permits for significant industrial users discharging to POTWs which have not been delegated authority to issue wastewater discharge permits.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 28 There are a number of functions required by the Pretreatment Pr ogram which the Department is delegating to such POTWs because they are in a better position to implement the requirements (e.g., tracking the number and general na ture of industrial dischargers to the sewerage system). The requirements for a Pretreatment Program are containe d in Title 40, Part 403 of the Code of Federal Regulations. Under the requirements of the Pr etreatment Program [40 CFR 403.8(f)(1)(iii)], the Department is required to appr ove, condition, or deny new discharges or a significant increase in the discharge for existing significant industr ial users (SIUs) [40 CFR 403.8 (f)(1)(i)]. The Department is responsible for issuing stat e waste discharge permits to SIUs and other industrial users of the Permittee's sewer system. Industrial dischargers must obtain these permits from the Department prior to the Permittee accepting the discharge [WAC 173-216-110(5)] (Industries discharging wastewater that is similar in character to domestic wastewater are not required to obtain a permit. Such dischargers sh ould contact the Department to determine if a permit is required.). Industrial dischargers need to apply for a state waste discharge permit sixty (60) days prior to commencing discharge. The conditions contained in the permits will include any applicable conditions for categorical discha rges, loading limitations included in contracts with the POTW, and other conditions necessary to assure compliance with state water quality standards and biosolids standards.
The Department requires this POTW to fulfill some of the functions required for the Pretreatment Program in the NPDES permit (e.g., tracking the number and general nature of industrial dischargers to the sewage system). The POTW's NPDES permit will require that all SIUs currently discharging to the POTW be iden tified and notified of the requirement to apply for a wastewater discharge permit from the Depart ment. None of the obligations imposed on the POTW relieve an industrial or commercial discharger of its pr imary responsibility for obtaining a wastewater discharge permit (if required), incl uding submittal of engineering reports prior to construction or modification of facilitie s [40 CFR 403.12(j) and WAC 173-216-070 and WAC 173-240-110, et seq.].
Wastewater Permit Required

RCW 90.48 and WAC 173-216-040 require SIUs to obtain a permit pr ior to discharge of industrial waste to the Permittee's sewerage system. Th is provision prohibits the POTW from accepting industrial wastewater from any such discharger s without authorization from the Department.
Requirements for Routine Identificati on and Reporting of I ndustrial Users The NPDES permit requires nonde legated POTWs to "take con tinuous, routine measures to identify all existing, new, and proposed SIUs a nd potential significant in dustrial users (PSIUs) discharging to the Permittee's se werage system." Examples of such routine measures include regular review of business tax licenses for existi ng businesses and review of water billing records and existing connection authorizat ion records. System maintenance personnel can also be diligent during performance of their jobs in identifying and reporting as-yet unidentified industrial dischargers. Local newspapers, teleph one directories, and word-of-mouth can also be important sources of information regarding new or existing discharges. The POTW is required to notify an industrial discharger , in writing, of their responsibilit ies regarding application for a state waste discharge permit and to send a copy of the written notificati on to the Department. The Department will then take steps to soli cit a state waste discharge permit application.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 29 Annual Submittal of List of Industrial Users

This provision requires the POTW to submit annua lly a list of existing and proposed SIUs and PSIUs. This requirement is intended to update the Department as need ed on the status of industrial users in the POTW's service area, without requ iring the POTW to go through the process of performing a formal Industrial User Survey. This provision is normally applied to POTWs not serving industrial or commercial users. Although this permit does not require performance of an Industrial User Survey, th e Permittee is nevertheless required under the previous section, to take ade quate continuous routine measures to identify existing and new industrial discharges.
Duty to Enforce Discharge Prohibitions This provision prohibits the POTW from authorizi ng or permitting an industrial discharger to discharge certain types of waste into the san itary sewer. The firs t portion of the provision prohibits acceptance of pollutants which cause pa ss through or interference. The definitions of pass through and interf erence are in Appendix B of the Fact Sheet.
The second portion of this provision prohibits the POTW from accepting certain specific types of wastes, namely those which are explosive, flam mable, excessively acidic, basic, otherwise corrosive, or obstructive to the system. In addition, wastes with excessive BOD, petroleum-based oils, or wastes wh ich result in toxic gases are pr ohibited to be discharged. The regulatory basis for these prohibitions is 40 CFR Part 403, with the exception of the pH provisions which are based on WAC 173-216-060.
The third portion of this provi sion prohibits certain types of discharges unless the POTW receives prior authorization from the Departme nt. The discharges include cooling water in significant volumes, stormwater and other direct inflow sources , and wastewaters significantly affecting system hydraulic loading, which do not require treatment.
Support by the Department for Developing Par tial Pretreatment Program by POTW The Department has committed to providing techni cal and legal assistance to the Permittee in fulfilling these joint obligations, in particular, as sistance with developing an adequate sewer use ordinance, notification procedures, enforcemen t guidelines, and developing local limits and inspection procedures.

GENERAL CONDITIONS General Conditions are based directly on state an d federal law and regulations and have been standardized for all individual municipal NPDES permits issued by the Department.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 30 PERMIT ISSUANCE PROCEDURES

PERMIT MODIFICATIONS The Department may modify this permit to impo se numerical limitations, if necessary, to meet water quality standards, sediment quality standa rds, or ground water standards, based on new information obtained from sources such as insp ections, effluent monito ring, outfall studies, and effluent mixing studies. The Department may also modify this permit as a result of new or am ended state or federal regulations.

RECOMMENDATION FOR PERMIT ISSUANCE This proposed permit meets all st atutory requirements for author izing a wastewater discharge, including those limitations and conditions believe d necessary to protect human health, aquatic life, and the beneficial uses of waters of the state of Washingt on. The Department proposes that this permit be issued for five (5) years.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 31 REFERENCES FOR TEXT AND APPENDICES
Documents received by the Department fr om Southwest Suburban Sewer District EPA NPDES Form 2A Application Boure, Gary R. P.E., Pool Engineering In c., Secondary Treatment Project Engineering Report , August 1985. Henke, Evan P.E, CHS Engineer, Inc., Mill er Creek/Salmon Creek WWTP Improvements
, May 2002.
Horton, Dennis and Associates, Southwest S uburban Sewer District 1999 Comprehensive Sewer Plan , February 1999.

Standard Reference Documents Environmental Protection Agency (EPA)

1992. National Toxics Rule. Federal Register, V. 57, No. 246, Tuesday, December 22, 1992.
1991. Technical Support Document for Wa ter Quality-based Toxics Control . EPA/505/2-90-001. 1988. Technical Guidance on Supplementary St ream Design Conditions for Steady State Modeling . USEPA Office of Water, Washington, D.C. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water . EPA/600/6-85/002a. 1983. Water Quality Standards Handbook. USEPA Office of Water, Washington, D.C. Metcalf and Eddy. 1991. Wastewater Engineering, Tr eatment, Disposal, and Reuse . Third Edition, Tsivoglou, E.C., and J.R. Wallace. 1972. Characterization of Stream Reaeration Capacity . EPA-R3-72-012. (Cited in EPA 1985 op.cit.) Washington State Department of Ecology. 2002. Permit Writer’s Manual . Publication Number 92-109.

Water Pollution Control Federation. 1976. Chlorination of Wastewater

. Wright, R.M., and A.J. McDonnell. 1979. In-stream Deoxygenation Rate Prediction . Journal Environmental Engineering Division, ASCE. 105(EE2). (Cited in EPA 1985 op.cit.)FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 32 APPENDIX A—PUBLIC INVOLVEMENT INFORMATION
The Department has tentatively de termined to reissue a permit to the applicant listed on page one of this fact sheet. The permit contains condition s and effluent limitations which are described in the rest of this fact sheet.
Public Notice of Application (PNOA) was published on September 4, 2001, and September 11, 2002, in the Seattle Times to inform the public that an application had been submitted and to invite comment on the reissuance of this permit.
The Department published a Public Notice of Draft (PNOD) on March 17, 2003, in the Seattle Times to inform the public that a draft permit and fact sheet were available for review. Interested persons were invited to submit written comments regarding the draft permit. The draft permit, fact sheet, and related document s were available for inspection and copying between the hours of 8:00 a.m. and 5:00 p.m. weekdays, by appointment, at the regional office listed below. Written comments were mailed to: Water Quality Permit Coordinator Department of Ecology Northwest Regional Office 3190 160 th Avenue SE Bellevue, WA 98008 Any interested party may comment on the draft pe rmit or request a public hearing on this draft permit within the thirty (30)-day comment period to the address above. The request for a hearing shall indicate the interest of the party and the reasons why the hearing is warranted. The Department will hold a hearing if it determines ther e is a significant public interest in the draft permit (WAC 173-220-090). Public noti ce regarding any hearing will be circulated at least thirty (30) days in advance of the h earing. People expressing an intere st in this permit will be mailed an individual notice of hearing (WAC 173-220-100).
Comments should reference specific text follo wed by proposed modification or concern when possible. Comments may address technical i ssues, accuracy and completeness of information, the scope of the facil ity’s proposed coverage, adequacy of environm ental protection, permit conditions, or any other concern that woul d result from issuance of this permit.
The Department will consider all comments received within thirty (30) days from the date of public notice of draft indicated above, in formulating a fina l determination to issue, revise, or deny the permit. The Department's response to all significant comme nts is available upon request and will be mailed directly to peopl e expressing an interest in this permit. Further information may be obtained from th e Department by telephone, 425-649-7201, or by writing to the address listed above. This permit and fact sheet were written by Karen Burgess.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 33 APPENDIX B—GLOSSARY
Acute Toxicity —The lethal effect of a po llutant on an organism that occurs within a short period of time, usually 48 to 96 hours.

AKART —An acronym for “all known, available, a nd reasonable methods of prevention, control, and treatment.” Ambient Water Quality —The existing environmental cond ition of the water in a receiving water body.
Ammonia —Ammonia is produced by the breakdown of nitrogenous materials in wastewater. Ammonia is toxic to aquatic organisms, exerts an oxygen demand, and contributes to eutrophication. It also increases the amount of chlorine needed to disinfect wastewater. Average Monthly Discharge Limitation —The highest allowable aver age of daily discharges over a calendar month, calculated as the sum of all daily discharg es measured during a calendar month divided by the number of daily discharges measured during that month (except in the case of fecal coliform). The daily discharge is calculated as the average measurement of the pollutant over the day. Average Weekly Discharge Limitation —The highest allowable aver age of daily discharges over a calendar week, calculated as the sum of all daily discharges measured during a calendar week divided by the number of daily discharges measured during that week. The daily discharge is calculated as the averag e measurement of the pollutant over the day. Best Management Practices (BMPs) —Schedules of activities; prohibitions of practices; maintenance procedures; and other physical, struct ural and/or managerial practices to prevent or reduce the pollution of waters of the state. BMPs include treatment systems, operating procedures, and practices to control: plant s ite runoff, spillage or leaks, sludge or waste disposal, or drainage from ra w material storage. BMPs ma y be further categorized as operational, source control, erosion and sediment control, and treatment BMPs.
BOD 5 —Determining the Biochemical Oxygen Demand of an effluent is an indirect way of measuring the quantity of organic ma terial present in an effluent that is utilized by bacteria. The BOD 5 is used in modeling to measure the reduction of dissolved oxygen in a receiving water after effluent is discharged. Stress cau sed by reduced dissolved oxygen levels makes organisms less competitive and less able to sustai n their species in the aquatic environment. Although BOD is not a specific compound, it is defi ned as a conventional pollutant under the federal Clean Water Act. Bypass —The intentional diversion of waste stream s from any portion of a treatment facility.
CBOD 5 —The quantity of oxygen utilized by a mixe d population of microorganisms acting on the nutrients in the sample in an aerobic oxidatio n for five days at a controlled temperature of 20 degrees Celsius, with an inhibitory agent added to prevent the ox idation of nitrogen compounds. The method for determining CBOD 5 is given in 40 CFR, Part 136.
Chlorine —Chlorine is used to disinfect wastewaters of pathogens harm ful to human health. It is also extremely toxic to aquatic life.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 34 Chronic Toxicity —The effect of a pollutant on an orga nism over a relatively long time, often 1/10 of an organism's lifespan or more. Chr onic toxicity can measure survival, reproduction or growth rates, or other parameters to measure the toxic effects of a compound or combination of compounds.

Clean Water Act (CWA )—The Federal Water Pollution Control Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, 97-117; USC 1251 et seq. Combined Sewer Overflow (CSO) —The event during which excess combined sewage flow caused by inflow is discharged from a combined sewer, rather than conveyed to the sewage treatment plant because either th e capacity of the treatment pl ant or the combined sewer is exceeded. Compliance Inspection - Without Sampling —A site visit for the pur pose of determining the compliance of a facility with the terms and conditi ons of its permit or with applicable statutes and regulations. Compliance Inspection - With Sampling —A site visit to accomplish the purpose of a Compliance Inspection - Without Sampling and as a minimum, sampling and analysis for all parameters with limits in the permit to asce rtain compliance with those limits; and, for municipal facilities, sampling of influent to ascertain compliance with the percent removal requirement. Additional sampling may be conducted. Composite Sample —A mixture of grab samples collect ed at the same sampling point at different times, formed either by continuous sampling or by mixing a minimum of four discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time intervals proportional to stream flow, or collected by increas ing the volume of each aliquot as the flow increased while maintaining a constant time interval between the aliquots). Construction Activity —Clearing, grading, excava tion, and any other activity which disturbs the surface of the land. Such activities may include road building; construction of residential houses, office buildings, or industria l buildings; and demolition activity.
Continuous Monitoring —Uninterrupted, unless otherw ise noted in the permit.
Critical Condition —The time during which the combination of receiving water and waste discharge conditions have the highest potential for causing toxicity in the receiving water environment. This situation usually occurs wh en the flow within a water body is low, thus, its ability to dilute effluent is reduced.
Dilution Factor —A measure of the amount of mixing of effluent and receiving water that occurs at the boundary of the mixing zone. Expr essed as the inverse of the effluent fraction e.g., a dilution factor of 10 m eans the effluent comprises 10 % by volume and the receiving water 90%. Engineering Report —A document which thoroughly examines the engineering and administrative aspects of a particular domestic or industrial wastewater facility. The report shall contain the appropriate informati on required in WAC 173-240-060 or 173-240-130.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 35 Fecal Coliform Bacteria —Fecal coliform bacteria are used as indicators of pathogenic bacteria in the effluent that are harmful to humans. Pa thogenic bacteria in wast ewater discharges are controlled by disinfecting the wastewater. Th e presence of high numbers of fecal coliform bacteria in a water body can indicate the recent release of untreated wastewater and/or the presence of animal feces. Grab Sample —A single sample or measurement taken at a specific time or over as short period of time as is feasible.
Industrial User —A discharger of wastewater to the sanitary sewer which is not sanitary wastewater or is not eq uivalent to sanitary wastewater in character.
Industrial Wastewater —Water or liquid-carried waste from industrial or commercial processes, as distinct from domestic wastewater. These wastes may result from any process or activity of industry, manufacture, trade or business, from the developmen t of any natura l resource, or from animal operations such as feed lots, poultry houses, or dairies. The term includes contaminated storm water and, also, l eachate from solid waste facilities. Infiltration and Inflow (I/I) —"Infiltration" means the additi on of ground water into a sewer through joints, the sewer pipe material, cracks, and other defects. "Inflow" means the addition of precipitation-caused drainage from roof drains, yard drains, basement drains, street catch basins, etc., into a sewer.
Interference —A discharge which, alone or in conjuncti on with a discharge or discharges from other sources, both:

• Inhibits or disrupts the POTW, its treatmen t processes or operations, or its sludge processes, use or disposal; and

• Therefore is a cause of a vi olation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation) or of the prevention of sewage sludge use or dis posal in compliance with the following statutory provisions and regul ations or permits issued thereunder (or more stringent state or local regulations): Section 405 of the Clean Water Act, the Solid Waste Disposal Act (SWDA) [including Title II, more commonly referred to as the Resource Conservation and Recovery Act (RCRA), and including state regulations contained in any state sludge management plan prepared pursuant to Subtitle D of the SWDA], sludge regulations appearing in 40 CFR, Part 507; the Clean Air Act; the Toxic Substances Control Act; and the Mari ne Protection, Research, and Sanctuaries Act. Major Facility —A facility discharging to surface water with an EPA rating score of >80 points based on such factors as flow volume, toxic pollutant potential, and public health impact. Maximum Daily Discharge Limitation —The highest allowable daily discharge of a pollutant measured during a calendar day or any 24-hour period that reas onably represents the calendar day for purposes of sampling. The daily discharg e is calculated as the average measurement of the pollutant over the day. Method Detection Level (MDL) —The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is above zero and is determined from analysis of a sample in a given matrix containing the analyte.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 36 Minor Facility —A facility discharging to surface water with an EP A rating score of <80 points based on such factors as flow volume, toxic pollutant potential, and public health impact. Mixing Zone —A volume that surrounds an effluent discharge within which water quality criteria may be exceeded. The area of the author ized mixing zone is specified in a facility's permit and follows procedures outlined in state regulations (chapter 173-201A WAC). National Pollutant Discharge Elimination System (NPDES) —The NPDES (Section 402 of the Clean Water Act) is the federal wastewater permitting system for discharges to navigable waters of the United States. Many states, in cluding the state of Washington, have been delegated the authority to issue these permits . NPDES permits issued by Washington State permit writers are joint NPDES/ state permits issued under both state and federal laws. Pass Through —A discharge which exits the POTW into waters of the stat e in quantities or concentrations which, alone or in conjunction with a discharge or discharges from other sources, is a cause of a vi olation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or dura tion of a violation), or which is a cause of a violation of state water quality standards. pH —The pH of a liquid measures its acidity or alkalinity. A pH of 7 is defined as neutral, and large variations above or below this value ar e considered harmful to most aquatic life. Potential Signific ant Industrial User —A potential significant industr ial user is defined as an industrial user which does not meet the criter ia for a significant industrial user, but which discharges wastewater m eeting one or more of the following criteria: a. Exceeds 0.5 % of treatment plant design capac ity criteria and discharges <25,000 gallons per day; or b. Is a member of a group of similar indust rial users which, taken together, have the potential to cause pass through or interf erence at the POTW (e.g., facilities which develop photographic film or paper, and car washes). The Department may determine that a discharger initially classified as a potential significant industrial user should be managed as a significant industrial user. Quantitation Level (QL) —A calculated value five times the MDL (method detection level). Significant Industrial User (SIU) — 1. All industrial users subject to Categorical Pretreatment St andards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N; and 2. Any other industrial user that : discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excludi ng sanitary, noncontact cooling, and boiler blow-down wastewater); contribut es 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* 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)].FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 37 Upon finding that the industria l user meeting the criteria in paragraph 2, above, has no reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or re quirement, the Control Authorit y* may at any time, on its own initiative or in response to a petition received from an indus trial user or POTW, and in accordance with 40 CFR 403.8(f)(6), determine that such industrial user is not a significant industrial user. *The term "Control Authority" refers to the Washington State Department of Ecology in the case of nondelegated POTWs or to the PO TW in the case of delegated POTWs.
State Waters —Lakes, rivers, ponds, streams, inland wa ters, underground waters, salt waters, wetlands, and all other surface waters and watercour ses within the jurisdiction of the state of Washington.
Stormwater —That portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a storm water drainage system into a defined surface wate r body, or a constructed infiltration facility. Technology-based Effluent Limit —A permit limit that is based on the ability of a treatment method to reduce the pollutant. Total Suspended Solids (TSS) —Total suspended solids are the particulate materials in an effluent. Large quantities of TSS discharged to a receiving water may result in solids accumulation. Apart from any toxic effects attrib utable to substances leached out by water, suspended solids may kill fish, shellfish, and other aquatic organisms by causing abrasive injuries and by clogging the gills and respir atory passages of vari ous aquatic fauna. Indirectly, suspended solids can screen out light and can promote and maintain the development of noxious conditions through oxygen depletion. Upset —An exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitati ons because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment f acilities, lack of preventative maintenance, or careless or improper operation. Water Quality-based Effluent Limit —A limit on the concentration or mass of an effluent parameter that is intended to prevent the con centration of that parameter from exceeding its water quality criterion after it is di scharged into a receiving water.

Week— For the purposes of the perm it, the week is defined at Sunday through Saturday.FACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 38 APPENDIX C—TECHNICAL CALCULATIONS

Several of the Excel ® spreadsheet tools used to evaluate a discharger’s ability to meet Washington State’s water quality standards can be found on the Department’s homepage at http://www.ecy.wa.gov

. List of Tables

Table 1: Salmon Creek WWTP Influe nt DMR Data for 7/1/97 to 7/1/02

Table 2: Salmon Creek WWTP Efflue nt DMR Data for 7/1/97 to 7/1/02 Table 3: Water Quality Criteria Worksheet
Table 4: Ammonia Conversion Spreadsheet

Table 5: Reasonable Potential Calculation Table 6: Water Quality-base d Human Health Calculation

Table 7: Potential for Sediment ContaminationFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 39

APPENDIX D—EPA NPDES APPLICATION (PART D) TESTING REQUIREMENTS

The following pollutant scan data are required at the time of NPDES permit application for municipal treatment facilit ies with design flow greater than 1.0 mgd. At least three scans are required, conducted during the term of the previous permit.

METALS & MISC. VOL. ORGANICS (Cont.) BASE NEUTRALS (Cont.) Antimony Ethylbenzene Bis (2-Chloroethyl)-Ether Arsenic Methyl Bromide Bis (2-Chloroiso-Propyl) Ether Beryllium Methyl Chloride Bis (2-Ethylhexyl) Phthalate Cadmium Methylene Chloride 4-Bromophenyl Phenyl Ether Chromium 1,1,2,2-Tetrachloro-Ethan e Butyl Benzyl Phthalate Copper Tetrachloro-Ethylen e 2-Chloronaphthalene Lead Toluene 4-Chlorphenyl Phenyl Ether Mercury 1,1,1-Trichloroethane Chrysene Nickel 1,1,2-Trichloroethan e Di-N-Butyl Phthalate Selenium Trichlorethylene Di-N-Octyl Phthalate Silver Vinyl Chloride Dibenzo(A,H) Anthracene Thallium 1,2-Dichlorobenzene Zinc ACID EXTRACTABLES 1,3-Dichlorobenzene Cyanide P-Chloro-M-Cresol 1,4-Dichlorobenzene Total Phenolic Compounds 2-Ch lorophenol 3,3-Dichlorobenzidine Hardness (As CaCO 3 ) 2,4-Dichlorophenol Diethyl Phthalate 2,4-Dimethylphenol Dimethyl Phthalate VOLATILE ORGANICS 4,6-Dinitro-O-Cresol 2,4-Dinitrotoluene Acrolein 2,4-Dinitrophe nol 2,6-Dinitrotoluene Acrylonitrile 2-Nitrophenol Fluoranthene Benzene 4-Nitrophenol Fluorene Bromoform Pentachlorophenol Hexachlorobenzene Carbon Tetrachloride Phenol Hexachlorobutadiene Clorobenzene 2,4,6-Trichlorophenol Hexachlorocyclo-Pentadiene Chlorodibromo-Methane Hexachloroethane Chloroethane BASE NEUTRALS Indeno(1,2,3-CD)Pyrene 2-Chloro-Ethylvinyl Ether Acenaphthene Isophorone Chloroform Acenaphthylene Naphthalene Dichlorobromo-Methane Anthracene Nitrobenzene 1,1-Dichloroethane Benzidine N-Nitrosodi-N-Propylamine 1,2-Dichloroethane Benzo(A)Anthra cene N-Nitrosodi-Methylamine Trans-1,2-Dichloro Ethylene 3,4 Benzo- Fluoranthene N-Nitrosodi-Phenylamine 1,1-Dichloroethylene Benzo(Ghi)Perylene Phenanthrene 1,2-Dichloropropane Benzo(K)Fluoranthene Pyrene 1,3-Dichloro-Propylene Bis (2-Chloroe thoxy) Methane 1,2,4-TrichlorobenzeneFACT SHEET FOR NPDES PERMIT WA-002277-2 Salmon Creek Wastewater Treatment Plant

Page 40 APPENDIX E—RESPONSE TO COMMENTS

No comments were received dur ing the public comment period.