ENGINEERING EVALUATION REPORT

PLANT NAME United States Mint

APPLICATION NUMBER 19110

PLANT NUMBER 5474

DATE 11-13-2008

1. BACKGROUND

On October 24, 2007, a major revision to the Airborne Toxic Control Measure (ATCM) for 

Chromium Plating and Chromic Acid Anodizing became law in California. As a result, the permit 

conditions for the District chrome platers (there are no chromic acid anodizers operating in the 

BAAQMD) need to be revised to address these changes. Following is a listing of the sources 

involved and the current and revised condition numbers. The ATCM can be found at the following 

website: http://www.arb.ca.gov/toxics/atcm/chroatcm.pdf

Source Old Cond New Cond Bath Control Abatement-1 Abatement-2

8 16712 16712 Floating Balls A-2 Mapco 

Enforcer III

A-3 HEPA

9 “ “ “ “ “

District regulations allow the APCO to make changes of permit conditions, based on certain 

criteria, enumerated in Reg 2-1-403:

Permit Conditions: Except as to permit applications reviewed in accordance with

Section 2-1-311, the APCO may impose any permit condition that he deems

reasonably necessary to insure compliance with federal or California law or District

regulations. For any permit application which was reviewed as a ministerial project in

accordance with Section 2-1-311, the APCO shall only impose permit conditions as

set forth in the District's Permit Handbook for the type of source being permitted. The

APCO may require the installation of devices for measurement or analysis of source

emissions or ground-level concentrations of air contaminants.

The proposed condition changes are to ensure compliance with the Chrome Plating ATCM, 

revised 10-24-2007.

2. EMISSION CALCULATIONS

The new permitted emission level will be 0.0015 mg/a-hr. Hence the following shows the 

permitted hex chrome emission rates before and after the permit condition modification.

Basis Throughput, a-hr/yr Factor, mg/a-hr Emissions, lb/yr

Current 1,400,000 0.006 0.0185

Post-ATCM 1,400,000 0.0015 0.00463

Net Difference 0 0.0045 0.014

3. CEQA
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Since the change of conditions will result in a decrease in the permitted emission levels, this 

application is exempt from CEQA review per Reg 2-1-312.1.

4. BEST AVAILABLE CONTROL TECHNOLOGY

Emissions are decreasing, therefore BACT is not applicable.

5. EXEMPTIONS

There are no applicable exemptions.

6. OFFSETS

Offsets are not applicable, since emissions decrease, therefore no offset triggers are exceeded.

7. TOXIC EVALUATION

Permitted emission levels decrease, therefore no toxic evaluation is required. Previous toxic risk 

evaluations have been conducted showing there are no significant risks to any member of the 

public from these operations. It should be noted that the risks were less than 10 in a million at the 

previous emission level, 0.0185 lb/yr. We would therefore expect the risk at the new control level 

to remain below 10 in a million.

8. STATEMENT OF COMPLIANCE

The purpose of revising the permit conditions is to ensure that the facility complies with the newly 

revised air toxic control measure.

9. CONDITIONS

The previous version of Condition 16712 is presented in this application, as is the revised 

Condition 16712.

10. RECOMMENDATIONS

Issue a Change of Condition letter for the aforementioned sources, subject to the revised 

Condition 16712.

OLD CONDITION 16712

 COND# 16712 --------------------------------------

 1. Annual Usage 

 The total annual (net) throughput

 from chrome plating tanks S-8 and S-9

 shall not exceed 1.4 million
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 ampere-hours in any consecutive

 twelve-month period.

 (Basis: Voluntary Toxic Risk Reduction) 

 2. Abatement 

 This source shall not be operated

 unless a layer of floating plastic

 balls is maintained in the bath in

 accordance with manufacturers

 instructions and all chrome plating

 tank emissions are vented through

 A-2 Mapco Enforcer III Mist

 Eliminator System and A-3 HEPA

 Filtration Unit. All emissions

 shall be exhausted from P-4 emission

 point. The abatement system shall be

 well maintained and kept in good

 operating condition.

 (Basis: Toxic Risk) 

 3. Emission Limits 

 Emissions of hexavalent chromium

 shall not exceed 0.0045 milligram per

 ampere-hour (mg/a-hr) after abatement.

 (Basis: Toxic Risk) 

 4. Source Test 

 Compliance Source Test: To demonstrate

 compliance with condition 3 above,

 the US Mint must perform a

 District-approved source test (according

 to a District approved protocol) on

 the exhaust stack within 60 days of

 permit approval. All source tests used

 to demonstrate compliance shall determine

 the mass emissions of both total and

 hexavalent chromium in g/hr, mg/a-hr,

 and mg/dscm as emitted after abatement.

 A complete report shall be submitted

 to the District's Source Test Manager

 within 60 days of the source test

 and shall demonstrate compliance with

 Condition 3, above.

 [Basis: Reg 8 Rule 16 (d)] 

 5. Parameter Monitoring 

 a) To demonstrate compliance with

 Condition 1, above, the US Mint

 shall install, operate and maintain

 a continuous recording,

 non-resettable ampere-hour meter
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 that operates on the electrical

 power lines connected to the tank

 rectifier. A separate meter

 shall be hard-wired for each rectifier

 if applicable.

 [Basis: Reg 8 Rule 16 (e)(1)] 

 b) The US Mint shall continuously

 monitor the pressure drop across

 A-2 Mist Eliminator System. The gauge

 shall be located so that it can be

 easily visible and in clear sight

 of the operation or maintenance

 personnel. The pressure drop across A-2

 mist eliminator system shall

 be maintained within the range of 2.1

 and 4.1 inches of water.

 [Basis: Reg 8 Rule 16 (e)(2),

 Compliance Source Test dated 3/20/2001] 

 c) The US Mint shall continuously

 monitor the pressure drop across

 A-3 HEPA Filtration Unit. The gauge

 shall be located so that it can be

 easily visible and in clear

 sight of the operation or maintenance

 personnel. The pressure drop across

 the HEPA Filtration System shall be maintained

 within the range of 0.6 and 2.6 inches water.

 [Basis: Reg 8 Rule 16 (e)(2),

 Compliance Source Test dated 3/20/2001] 

 6. Inspection/Maintenance

 [Basis: Reg 8 Rule 16 (f)(1)] 

 a) The US Mint shall perform visual

 inspections of A-2 Mist

 Eliminator System and A-3 HEPA

 Filtration Unit at a frequency

 of at least one time per

 calendar quarter. This visual

 inspection is to ensure that

 there is proper drainage, no

 unusual chromic acid buildup on

 the pads, and no evidence of chemical

 attack that would affect the

 structural integrity of the devices. 

 b) US Mint shall visually inspect the

 back portion of the mesh pad closest

 the stack at a frequency of at least

 one time per quarter to ensure

 there is no breakthrough of chromic

 acid mist. 
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 c) US Mint shall visual inspect ductwork

 from tank to the control device at

 a frequency of at least one time

 per calendar quarter to ensure there

 are no leaks. 

 d) US Mint shall perform washdowns

 of the mist eliminator system at

 a frequency as recommended by the

 manufacturer. 

 e) The ampere-hour meter shall be

 installed and maintained as per

 manufacturer's recommendations. 

 7. Operation and Maintenance Plan

 [Basis: Reg 8 Rule 16 (g)] 

 a) US Mint shall prepare an operation

 and maintenance (O & M) plan.

 The plan shall incorporate the

 inspection and maintenance

 requirements as noted in Condition

 6, above, and shall include the

 following elements: a) a

 standardized checklist to

 document the operation and

 maintenance of the source, the

 add-on air pollution control

 devices, and the process and

 control system monitoring equipment,

 and b) procedures to be followed

 to ensure that equipment is properly

 maintained. 

 b) O & M plan retention: US Mint shall

 keep the written operation and

 maintenance plan on record after it

 is developed to be made available

 for District inspection, upon request. 

 c) Changes to the O & M plan: Any

 changes made to the O & M Plan

 should document in an addendum

 to the plan. In addition,

 US Mint shall keep previous

 versions of the O & M Plan on record

 to be made available for District

 inspection upon request, for a

 period of 5 year after each revision

 to the plan. 

 d) Revisions to address breakdowns:

 The O & M Plan shall be revised as

 necessary to minimize breakdowns. 
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 To satisfy the inspection and

 maintenance procedures, US Mint may

 use applicable standard operating

 procedure (SOP) manuals, Occupational

 Safety and Health Administration

 (OSHA) plans, or other existing plans,

 provided the alternative plans meet

 the requirements of this subsection. 

 8. Recordkeeping

 [Basis: Reg 8 Rule 16 (h)] 

 The following records shall be kept

 and maintained by US Mint for at least

 five years total; and at least two

 years on site. 

 a) Inspection records for A-2 Mist

 Eliminator System and A-3 HEPA

 Filtration Unit: US Mint shall

 maintain inspection records to

 document that the Inspection/

 Maintenance requirements and the

 O & M Plan as required by Conditions

 6 and 7, above, respectively have

 been met. The record can take the

 form of a checklist and should

 identify 1) the device inspected,

 2) the date and time of the inspection,

 3) a brief description of the working

 condition of the device during

 inspection, 4) maintenance activities

 performed on the components of the air

 pollution control system (i.e. ductwork,

 filter pad, fan, etc), and 5) any action

 taken to correct deficiencies found

 during inspection. 

 b) US Mint shall maintain records to

 demonstrate that the inspection and

 maintenance requirements of Condition

 6, above, have been satisfied. 

 c) Performance test records: US Mint

 shall maintain test reports documenting

 the conditions and results of all

 performance tests. 

 d) Monitoring data records: US Mint

 shall maintain records of monitoring

 data as required by Conditions 1 and

 5, as follows: 

 e) Breakdown records: US Mint shall
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 maintain records of the occurrence,

 duration, and cause (if known) and

 action taken on each breakdown. 

 f) Records of excesses: US Mint shall

 maintain records of exceedances of:

 a) the emission limitation identified

 in Condition 3; b) the monitoring

 parameter values of Condition 5; c)

 any site-specific operating parameters

 established for alternative equipment.

 The records shall include the date

 of the occurrence, the duration,

 cause (if known), and where possible,

 the magnitude of any excess emissions. 

 9. Reporting 

 a) On an annual basis, US Mint shall

 prepare a summary report to the

 District to document the ongoing

 compliance status. This report

 shall be made available to the

 District upon request.

 [Basis: Reg 8 Rule 16 (i)(3)(2)] 

 b) Breakdown reports: US Mint shall

 report breakdowns as required by the

 District breakdown procedures

 identified in Regulation 1.

 [Basis: Reg 8 Rule 16 (i)(4)]

NEW CONDITION 16712

COND# 16712 --------------------------------------

 The owner/operator shall comply with the following

 Conditions for Sources 8 and 9 Chrome Plating Tanks.

 Basis refers to either BAAQMD Regulations/Rules or

 California Code of Regulations, Title 17, Section

 93102 - 93102.16 and associated appendices, unless

 otherwise noted. 

 1. Performance Standards 

 a) Emission Limits effective through 10-23-2009: 

 Emissions of hexavalent chromium shall not exceed

 0.006 mg per ampere-hour (mg/amp-hr) after abatement.

 [Basis: 93102.4(a)(1)] 

 b) Emission Limits effective 10-24-2009: 
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 Emissions of hexavalent chromium shall not exceed

 0.0015 mg per ampere-hour (mg/amp-hr) after abatement.

 [Basis: 93102.4(b)(1) 

 c) Throughput: The total annual combined throughput at

 S-8 and S-9 shall not exceed 1.4 million ampere-hours

 in any consecutive 12-month period.

 [Basis: 93102.4(b)(1)] 

 d) The requirements of Parts 1a and 1b of this condition

 and the O&M Plan provisions do not apply during periods

 of equipment breakdown, provided the provisions of the

 District's breakdown rules are met. [Basis: 93102.2(b)]

 2. Abatement 

 a) The owner/operator shall abate at all times during

 operation of S-8 and S-9 with plating tank

 emissions vented through A-2 Mapco Enforcer III

 Mist Eliminator Unit, A-3 HEPA Filtration Unit,

 and exhausted from P-4 Emission point. 

 The ventilation and abatement system shall be properly

 maintained and kept in good working condition. 

 b) Mechanical fume suppressant: The owner/operator uses a

 layer of floating plastic balls to assist in fume

 suppression prior to downstream abatement. A

 sufficient number of floating plastic balls shall be

 maintained on the plating bath liquid surface such that

 when the bath is non- operational, the entire exposed

 liquid surface area is covered with at least one layer

 of balls. The interstitial areas between the adjacent

 plastic balls and other areas of the bath surface area

 occupied with plating parts or bath equipment shall not

 be considered to be part of the liquid surface in need

 of being covered with balls.[Basis: 93102.9(f)] 

 3. Source Test 

 a) The owner/operator shall perform a source test by

 October 24, 2009 to demonstrate compliance with the

 emission performance standard specified in part 1b. 

 An existing District-approved source test may be used

 to demonstrate compliance with this part, as long as

 the existing source test was conducted in

 accordance with ATCM Section 93102.7(b) & (c).

 [Basis: 93102.7(a)(1)(A)] 

 b) The owner/operator shall perform source tests to

 demonstrate compliance according to the following

 schedule: 

 i. Unless Part 3.b)ii. is satisfied, subsequent
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 source testing shall be performed no later

than 36 months after the date of the previous

District-approved source test demonstrating

compliance.

 ii. If the previous two consecutive source tests

 demonstrate compliance, the subsequent tests

 shall be performed no later than 48 months

after the previous source test.

 iii. If a source test demonstrates non-compliance,

 then the owner/operator must perform another

source test to demonstrate compliance.

Subsequent source tests to demonstrate

compliance shall be performed no later than

24 months after the previous source test. If

after two consecutive source tests at the 24

month frequency, both of which demonstrate

compliance, the source test frequency reverts

to the original schedule in Part 3.b)i. 

 c) Non-compliant source test: After conducting a

 source test which demonstrates non-compliance the

 owner/operator shall review and adjust or repair the

 plating operation and associated emission control

 system. A source test to demonstrate compliance

 shall be performed no later than 30 days after the

 chrome plating system adjustments/repairs are

 completed. 

 d) Any chrome plating bath that is non-operational at

 the time a source test is due does not have to be

 tested at that time. Upon subsequent start-up of

 any such bath, a source test shall be conducted

 within 30 days. 

 e) Source Testing Protocol: A written source test

 protocol based on 93102.7(c) shall be provided for

 District approval prior to conducting any source

 test for compliance. This source testing protocol

 shall include testing methods, length of sample

 period, plating facilities to be operated during the

 source test, sampling equipment and methods, as well

 as the planned date for the source test. 

 For the purpose of maintaining ongoing compliance,

 the following parameters shall be monitored and

 recorded at the listed frequency during the source

 testing period: 

 i. Bath coverage-floating balls: visually estimate

 percent bath coverage prior to start of bath

operation (when bath is quiescent).

 ii. A-2 Pressure Drop: record pressure drop at

 least one time every 15 minutes of operation.

 iii. A-3 Pressure Drop: record pressure drop at

 least one time every 15 minutes of operation. 
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 f) The owner/operator shall contact the District Source

 Test Section at least 14 days in advance of the

 source test or as directed by the ATCM to obtain

 approval of the test protocol. The owner/operator

 shall notify the District Source Test Section at

 least 7 days in advance of each scheduled source

 test. [Basis: 93102.7] 

 4. Training 

 No later than October 24, 2009, and within every two

 calendar years thereafter, the owner or operator shall

 ensure that hexavalent chrome based plating operations

 (including environmental compliance/recordkeeping) are

 under the direction of the owner or operator or current

 employee who is onsite and has completed the ARB

 Compliance Assistance Training Course for chrome

 plating and anodizing. [Basis: 93102.5(b)] 

 5. Housekeeping 

 The following housekeeping requirements shall be

 implemented to reduce potential hexavalent chrome

 fugitive emissions: [Basis: 93102.5(c)] 

 a) Chromic acid materials shall be stored in a closed

 container in an enclosed storage area. 

 b) Chromic acid materials shall be transported from

 storage to the bath in a closed container. 

 c) Any liquid or sold hexavalent chrome containing

 material that is spilled shall be contained or

 cleaned up within one hour after being spilled. 

 d) Dragout shall be minimized by: 

 i. handling the plated parts so that chromic acid

 is not dripped outside the tank, and

 ii. installing splash guards at the tank to

 minimize overspray and to ensure that chrome

solution is returned to the tank. 

 e) Surfaces within the chrome storage area and the

 walkways and other areas potentially contaminated

 with hexavalent chrome, shall be cleaned at least

 one time every seven days by either HEPA vacuuming,

 damp cloth hand wiping, wet mopping, use of non-

 toxic dust suppressants or any other District-

 approved method. 

 f) Buffing, grinding or polishing areas shall be

 separated from the chrome plating operation by a

 physical barrier, which may include, but is not
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 limited to vertical plastic strip curtains. 

 g) Chromium containing wastes generated as a result of

 any of the above housekeeping activities shall be

 stored, disposed of, recovered, or recycled using

 practices that minimize fugitive dust. 

 6. Monitoring 

 a) Each rectifier shall be hard-wired to a single non-

 resettable meter which records ampere-hours

 continuously during rectifier operation. Each

 ampere-hour meter shall be installed and maintained

 per manufacturer's specifications. The

 owner/operator shall record the total ampere-hours

 used during each month.

 [Basis: 93102.10(a), 93102.12(c)(1)] 

 b) A-2 Pressure Drop: The owner/operator shall

 continuously monitor the pressure drop across A-2

 Mapco Enforcer III unit. The pressure drop shall be

 maintained within plus or minus 2 inches of water of

 the value established during the most recent source

 test to demonstrate compliance with the emission

 limitations of Part 1. Pressure drop readings shall

 be recorded at a frequency of at least one time per

 operating week. [Basis: 93102.9(b), 9102.12(c)(2)]

 c) A-3 Pressure Drop: The owner/operator shall

 continuously monitor the pressure drop across A-3

 HEPA filter. The pressure drop shall be maintained

 within minus 1⁄2 times to +2 times the inches of water

 of the value established during the most recent

 source test to demonstrate compliance. Pressure

 drop readings shall be recorded at a frequency of at

 least one time per operating week.

 [Basis: 93102.9(b), 93102.12(c)(2)] 

 d) The owner/operator shall visually inspect the

 electroplating bath for coverage of floating plastic

 balls comparable to the coverage observed during the

 performance test. Visual inspections shall be

 conducted and recorded at a frequency of at least

 one time per operating day. [Basis: 93102.9(f)] 

 7. Operation & Maintenance (O&M) Plan 

 The owner/operator shall prepare an operation and

 maintenance plan for the chrome plating operation,

 which shall be retained onsite and made available for

 inspection upon request. Any revisions to the O & M

 Plan shall be documented in an addendum and all

 versions shall be maintained for a period of 5 years

 after each revision to the plan. The O&M Plan shall at

 a minimum include: 
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 a) The inspection and maintenance requirements for the

 air pollution control equipment and amp-hr

 meters/totalizers. [Basis: 93102.11] 

 b) A checklist to document the inspection, operation

 and maintenance for the chrome plating operation,

 including steps to be taken to correct operating

 deficiencies. [Basis: 93102.11] 

 8. Inspection & Maintenance Frequency 

 a) The owner/operator shall perform visual inspections

 of the abatement systems and associated ductwork

 pursuant to ATCM Section 93102.10(a) at least once

 per calendar quarter and conduct wash downs of the

 Mapco Enforcer III unit per manufacturer

 recommendations. [Basis: 93102.10(a) and Reg 2-5] 

 b) In order to demonstrate compliance with Part 8a,

 the owner/operator shall record the equipment being

 inspected, date, brief description of the working

 condition of the device during the inspections, any

 maintenance activities performed on the components

 of the air pollution control systems, and any

 actions taken to correct deficiencies found during

 the inspection. 

 9. Recordkeeping 

 The owner/operator shall maintain the following records

 for at least five years, with the most recent two years

 maintained onsite. 

 a) Inspection Records to demonstrate that such

 inspections were done in accordance with the

 provisions of Section 93102.10 and the O&M Plan.

 Such records can take the form of a checklist and

 shall identify the devices inspected, the date and

 time of the inspection, a brief description of the

 working condition and any corrective actions. 

 b) The owner/operator shall:

 [Basis: 93102.12] 

 i. Record the percent coverage of floating

 plastic balls at least one time per

operating day - prior to bath operation.

 ii. Record monthly and cumulative 12-month

 rectifier ampere-hour totals, and

 iii. Record the pressure drop across the

 abatement device(s) at least once per

operating week, 

 c) Breakdown Records noting the occurrence,
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 duration, cause (if known), and action taken. 

 d) Records of excesses of the emission limitations

 set forth in Part 1 or the monitoring parameters

 established under Part 6 noting any exceedances of

 the ampere-hour throughput or pressure drop limits.

 e) Housekeeping Records demonstrating compliance

 with Part 3, above, including date and time of

 housekeeping activity. 

 10. Reporting 

 a) Source Test Reports: The owner/operator shall

 report source test results used to demonstrate

 compliance to the District Source Test Section no

 later than 60 days after the test date. The content

 of the source test reports shall contain the

 information identified in Appendix 1 of the

 applicable ATCM. Source test records shall be

 maintained onsite at the facility and made available

 to the District upon request, for a period of 5

 years from the date of the source test.

 [Basis: 93102.13(a)] 

 b) Annual Compliance Status Report: The owner/operator

 shall submit an annual compliance status report to

 the District on or before February 1, and shall

 include the following information for the preceding

 calendar year. 

 The content of the ongoing status shall include the

 information identified in Appendix 3 of the

 applicable ACTM. The report shall contain the name,

 title and signature of the responsible official who

 is certifying the accuracy of the report.

 [Basis: 93102.13(c)]