DRAFT 

Date: July 16, 2010 

Subject: Emissions Reductions and Cost Effectiveness of HEPA Filter Retrofits for 

Chromium Electroplating 

 Emission Standards Technical Support and Post Promulgation Activities 

 EPA Contract No. EP-D-06-118; EPA Work Assignment No. 4-6 

 RTI Project No. 0210426.004.006 

From: James Cunningham 

 Richard Marinshaw 

To: Phil Mulrine, EPA/OAQPS/SPPD/MMG 

The purpose of this memorandum is to present the estimated emissions reductions, costs, 

and cost effectiveness of retrofitting high efficiency particulate air (HEPA) filters on all existing 

sources subject to the National Emission Standards for Chromium Emissions from Hard and 

Decorative Chromium Electroplating and Chromium Anodizing Tanks (Chromium 

Electroplating NESHAP, 40 CFR 63, subpart N). Retrofitting HEPA filters is being considered 

as one regulatory option for reducing the risk associated with chromium emissions from 

chromium electroplating and anodizing. 

Section I of this memorandum presents estimated baseline emissions of chromium 

compounds from existing electroplating and anodizing tanks subject to the NESHAP. Emissions 

reductions associated with retrofitting HEPA filters on all existing affected sources are presented 

in Section II. Section III describes the basis for, and results of, the cost estimates for HEPA filter 

retrofits nationwide, and the resulting cost-effectiveness is summarized in Section IV. 

References are provided in Section V. 

I. Baseline Emissions for Chromium Electroplating and Anodizing Sources

 The basic methodology used to estimate baseline emissions from chromium 

electroplating and anodizing sources was as follows: 

1. Estimate the number of plants of each type (hard chromium electroplating, decorative 

chromium electroplating, and chromium anodizing); 

2. For each type of plant, estimate the number of each size (small, medium, large); 

3. Estimate uncontrolled emissions from each plant type and size; 

4. Estimate control method distribution and apply control efficiencies; and 

5. Sum up the controlled emissions nationwide. 
2 

 Estimated Number of Plants by Type

 Table 1 summarizes the estimated number of chromium electroplating and anodizing 

plants nationwide. The basis for these estimates is provided in Reference 1. 

Table 1. Estimated Number of Chromium Electroplating Plantsa

Process 

Estimated No. 

of plants 

Hard chromium electroplating 790 

Decorative chromium electroplating 740 

Chromium anodizing 240 

Total 1,770 a Reference 1. 

 Estimated Number of Plants by Size

 The numbers of chromium electroplating and anodizing plants by size were estimated 

using the model plants and plant distributions developed for the NESHAP and documented in 

Chromium Emissions from Chromium Electroplating and Chromic Acid Anodizing Operations -- 

Background Information for Proposed Standards (Reference 2). Three sizes of model plants 

(small, medium, and large) were developed for hard and decorative chromium electroplating, and 

two sizes of model plants (small and large) were developed for chromium anodizing. Table 2 

summarizes the resulting nationwide breakdown of plants by type and size. 

Table 2. Distribution of Model Plants by Size and Typea

Electroplating Type Size % of total 

No. of plants 

nationwide 

Small 70% 553 

Medium 20% 158 

Large 10% 79 Hard Chromium 

Total 790 

Small 80% 592 

Medium 15% 111 

Large 5% 37 Decorative Chromium 

Total 740 

Small 75% 180 

Chromium Anodizing Large 25% 60 

Total 240 

 Total, all plants 1,770 a

 Reference 2. 
3 

 Uncontrolled Emissions from Model Plants

 The uncontrolled model plant emissions developed for the NESHAP were used in the 

determination of baseline chromium compound emissions. Table 3 summarizes these emissions. 

Table 3. Uncontrolled Chromium Compound Emissions from Model Plantsa

Electroplating Type Size 

Uncontrolled Cr 

emissions, lbs/yr 

Small 110 

Hard Chromium Medium 926 

Large 3,530 

Small 13 

Decorative Chromium Medium 53 

Large 530 

Small 7.2 Chromium Anodizing Large 88 a

 Reference 2. 

 Control Efficiencies and Control Method Distribution

 To determine controlled (baseline) emissions nationwide, assumptions were made about 

the numbers and types of emission control technologies in use, and the control levels (control 

efficiencies) achieved by those technologies. For hard chromium electroplating tanks, the most 

commonly used controls are the composite mesh pad (CMP), packed bed scrubber (PBS), and 

mesh pad mist eliminator (MPME). In addition, as the result of the 2005 amendments to the 

NESHAP, some hard chromium electroplating tanks are controlled using only a wetting agent 

fume suppressant (WAFS). To estimate the impacts of the original NESHAP, the assumed 

control efficiencies for these devices were 99.5 percent for CMP and 99.0 percent for PBS and 

MPME. For WAFS, a control efficiency of 99.5 percent was used. For decorative chromium 

electroplating tanks and chromium anodizing tanks, the controls used include PBS, MPME, and 

CMP, but most tanks are controlled using WAFS. The same control efficiencies indicated above 

for hard chromium electroplating also apply to decorative chromium electroplating and 

chromium anodizing. A summary of the control efficiencies used is presented in Table 4. 

Table 4. Efficiencies of Chromium Electroplating Emission Controlsa

Control Method Efficiency, % 

Composite mesh pad (CMP) 99.5 

Packed bed scrubber (PBS) 99.0 

Mesh pad mist eliminator (MPME) 99.0 

Wetting agent fume suppressant (WAFS) 99.5 a Reference 2. 

 The distribution of emission control methods among the various types of chromium 

electroplating plants and plant sizes was estimated based on general knowledge of the industry. 

Large hard chromium electroplating plants generally are controlled with CMPs; some PBSs are 
4 

also used. For medium and small hard chromium electroplating plants, PBSs are more common. 

Some medium and small plants also use WAFS to control emissions. As noted above, WAFS is 

the most commonly used control method for decorative chromium electroplating and chromium 

anodizing plants. However, other controls (PBS, MPME) also are used. To estimate the 

distribution, the percentage of plants that use WAFS was first assumed; then the percentages of 

each type of add-on control devices were estimated. Since the control efficiencies for PBS and 

MPME are comparable, no distinctions were made between the two with respect to their 

distribution. Table 5 summarizes the assumed distribution of these controls among the various 

types of model plants. The resulting numbers of plants are summarized in Table 6. 

Table 5. Distribution of Emission Controls by Size and Type of Plant 

% of Total 

Electroplating Type 

Model 

Plant Size CMP PBS/MPME WAFS 

Small 16 64 20 

Hard Chromium Medium 54 36 10 

Large 90 10 0 

Small 0 10 90 

Decorative Chromium Medium 2 18 80 

Large 8 32 60 

Small 0 10 90 Chromium Anodizing Large 8 32 60 

 

Table 6. Distribution of Model Plants by Emission Control Method 

Number of Plants Nationwide 

Electroplating Type 

Model 

Plant Size CMP PBS/MPME WAFS 

Total 

Small 88 354 111 553 

Medium 85 57 16 158 

Large 71 8 0 79 Hard Chromium 

Total 790 

Small 0 59 533 592 

Medium 2 20 89 111 

Large 3 12 22 37 Decorative Chromium 

Total 740 

Small 0 18 162 180 

Chromium Anodizing Large 5 19 36 60 

Total 240 

 

 Estimated Controlled Baseline Emissions

 

 Using the data and distributions discussed above and summarized in Tables 1 through 6, 

nationwide baseline emissions of chromium compounds were estimated to be 3,279 pounds per 

year (lbs/yr) (1.64 tons per year [tons/yr]). This total is comprised of 3,030 lbs/yr for hard 
5 

chromium electroplating, 207 lbs/yr for decorative chromium electroplating, and 42 lbs/yr for 

chromium anodizing. Table 7 summarizes the results by model plant type and size. 

Table 7. Estimated Baseline Emissions of Chromium Compounds 

Electroplating Type Model Plant Size 

Nationwide 

Emissions, lbs/yr 

Small 499 

Medium 995 

Large 1,536 Hard Chromium 

Total 3,030 

Small 42 

Medium 35 

Large 130 Decorative Chromium 

Total 207 

Small 7 

Chromium Anodizing Large 35 

Total 42 

Nationwide total 3,279 

 

II. Estimated Emissions Reductions for HEPA Filter Retrofit

 To estimate the emissions reductions that would be achieved by retrofitting HEPA filters 

on all existing sources subject to the Chromium Electroplating NESHAP, the control efficiency 

of HEPA filters was first applied to uncontrolled baseline emissions. By definition, HEPA filters 

are designed to remove at least 99.97 percent of airborne particles that are 0.3 micrometers (μm) 

or larger in diameter. The only available particle size data for uncontrolled emissions from 

chromium electroplating sources, as summarized in Table 8, indicates that chromic acid mist 

emitted from hard chromium electroplating is comprised almost entirely of particles larger than 

0.3 μm. On this basis, it was assumed that HEPA filters would generally remove 99.97 percent 

of uncontrolled emissions from hard chromium electroplating, decorative chromium 

electroplating, and chromium anodizing sources. 

Table 8. Particle Size Data for Uncontrolled Hard Chromium Electroplating Emissionsa

Particle Size, μm Cumulative % less than 

8 82.6% 

2.4 67.7% 

0.5 6.9% a

 Reference 3. 

 From a model plant perspective, Table 9 summarizes the resulting nationwide emissions 

of chromium compounds from hard chromium electroplating, decorative chromium 

electroplating, and chromium anodizing assuming all existing tanks are retrofit with HEPA 
6 

filters. The table also shows the emissions reductions from baseline that would result from this 

option. Based on this analysis, retrofitting HEPA filters or all existing tanks subject to the 

NESHAP would reduce nationwide emissions by 3,121 lbs/yr (1.56 tons/yr) from 3,279 lbs/yr 

(1.64 tons/yr) to 158 lbs/yr (0.079 tons/yr). 

Table 9. Estimated Emissions Reductions for HEPA Filter Retrofit - Model Plant Basis 

Nationwide Emissions, lbs/yr 

Electroplating Type 

Model Plant 

Size Baseline 

HEPA Filter 

Retrofit 

Net Emissions 

Reductions 

Small 499 18 481 

Medium 995 44 952 

Large 1,536 84 1,452 Hard Chromium 

Total 3,030 146 2,884

Small 42 2.3 40 

Medium 35 1.8 33 

Large 130 5.9 124 Decorative Chromium 

Total 207 10.0 197

Small 7.1 0.39 6.7 

Chromium Anodizing Large 35 1.6 33 

Total 42 2.0 40

Nationwide total 3,279 158 3,121

 With respect to emissions limits, the Chromium Electroplating NESHAP distinguishes 

between four types of plants: large hard chromium electroplating, small hard chromium 

electroplating, decorative chromium electroplating, and chromium anodizing. Large hard 

chromium electroplating plants are defined as those that have a maximum cumulative potential 

rectifier capacity of at least 60 million ampere-hours per year (amp-hr/yr), and small facilities are 

those with a maximum cumulative potential rectifier capacity less than 60 million amp-hr/yr. 

These size distinctions differ from the model plant sizes for hard chromium electroplating. All 

large model plants would be classified as large hard chromium plants under the NESHAP, and 

all small model plants would be classified as small hard chromium plants under the NESHAP. 

However, the larger portion of medium size model plants would be classified as small, and the 

remainder would be classified as large under the NESHAP. For this analysis, it was assumed 

that 67 percent of the medium size model plants are small hard chromium plants under the 

NESHAP, and that those plants account for 33 percent of the emissions from medium size model 

plants. The remaining medium size model plants, and the emissions attributed to those plants, 

are assumed to represent large hard chromium plants under the NESHAP. Table 10 summarizes 

baseline emissions, emissions under the HEPA filter retrofit option, and the corresponding 

emissions reductions based on these assumptions. 
7 

Table 10. Estimated Emissions Reductions for HEPA Filter Retrofit - NESHAP Basis 

Nationwide Emissions, lbs/yr 

Plant Type 

No. of 

plants Baseline 

HEPA Filter 

Retrofit 

Net Emissions 

Reductions 

Large Hard Chromium 132 2,200 113 2,087

Small Hard Chromium 658 831 33 797

Decorative Chromium 740 207 10.0 197

Chromium Anodizing 240 42 2.0 40

Total 1,770 3,279 158 3,121

III. HEPA Filter Retrofit Costs

 This section describes the methodology, data, and assumptions used to estimate the costs 

of retrofitting HEPA filters on existing sources subject to the Chromium Electroplating 

NESHAP. In estimating costs, distinctions were made between emission control systems with 

existing add-on controls, and sources that use WAFS and are not equipped with add-on controls. 

For systems with existing add-on controls, a retrofit factor was incorporated into the basic HEPA 

filter system cost. For systems without existing add-on controls, a retrofit factor was not applied 

to the costs. However, it was necessary to include costs of an exhaust and ventilation system 

(hoods, ductwork, and fans) and a primary control device to remove the larger particles in the 

exhaust stream prior to the HEPA filter. The following sections provide additional details on 

how these costs were estimated. 

 Sources with Existing Add-On Controls

 Cost estimates were requested from three vendors for the complete installation new 

HEPA filter systems on systems designed for four exhaust flow rates: 6,000, 12,000, 18,000, 

and 40,000 actual cubic feet per minute (ACFM). Estimates were received from Oskar 

Environmental Inc. of Youngsville, NC and Flanders/CSC of Washington, NC. Because the 

quotes were for budgetary purposes, detailed itemization was not provided. The Flanders quote 

included an itemized list of components, but only a total cost for each system. The Oskar quote 

was itemized by the following: 1) fan and HEPA housing; 2) ducting and installation; 

3) estimated freight; and 4) filter replacement cost. The estimated freight and filter replacement 

costs were assumed equal to normalize the quotes for comparison. The quotes are presented in 

Appendix A of this document. 

 The capital and annual costs for each system were determined by the methods described 

in the EPA Air Pollution Control Cost Manual (Reference 4). Presented in Table 11 are the 

capital costs categories and the source of those rates, if not provided in the cost quotes. 
8 

Table 11. Cost Components and Assumptions Used to Estimate HEPA Filter Retrofit Costs 

Plant Type Oskar Environmental Flanders 

System Included Included 

Instrumentation Not included; assumed 11% of 

equipment cost 

Not included; assumed 11% of 

equipment cost 

Sales tax Assumed 6% Assumed 6% 

Freight Included Not included (used Oskar quote) 

Installation Included Included, but not itemized (used 

Oskar quote) 

Performance testing Not included; assumed 0.7% of 

installation cost 

Not included; assumed 0.7% of 

installation cost 

Contingencies Assumed 2.1% of installation cost Assumed 2.1% of installation cost 

Retrofit Cost Assumed 50% of capital cost Assumed 50% of capital cost 

 Table 12 presents the annual cost categories considered in the estimate, the assumptions 

used, and the information source. The filter replacement costs were provided in each quote, 

while the additional information was derived from various sources. For electricity costs, a unit 

price of $0.14 per kilowatt hour (kW-hr) was used (Reference 5). 

Table 12. Annual Cost Components and Assumptions Used for HEPA Retrofit Costs 

Cost Component Source/Method 

Labor hours CA ARBa

Filter Replacement Quotes 

Filter Disposal $930/5000 ft3/min.a

Electricity $0.14/kwhr 

Property Tax & Insurance 4% of capital costb

 a

 Reference 6. 

 b Reference 4. 

 The average total annual cost for each system was determined from the two quotes, and 

the resulting cost curve was determined using an interest rate of 7% and 20-year lifetime. The 

cost curve plotted exhaust flow (independent variable) versus total annual cost (dependent 

variable) and resulted in a R2

 value of 0.999. The equation of the best-fit line was then used to 

determine the total annual cost for the model facilities for hard plating, decorative plating, and 

anodizing facilities. Presented in Figure 1 is the cost curve for retrofitting a new HEPA filter 

system on a chromium electroplating source with existing add-on controls. 
9 

Figure 1. Annualized Cost Curve for Retrofitting new HEPA Filter on Existing 

Chromium Electroplating Source with Existing Add-on Controls. 

 The cost curve was used to estimate the cost per model plant, which was then multiplied 

by the number of plants nationwide. Based on this methodology, the estimated annualized cost 

to retrofit a new HEPA filter on all sources subject to the NESHAP with existing add-on controls 

is $53.7 million. Table 13 shows the detailed cost and number of facilities for each type of 

model plant. 

Table 13. Nationwide Annualized Costs for HEPA Retrofit - Sources with Add-on Controls 

Model 

Plant Size 

Exhaust Flow 

Rate, ACFM 

Number of 

Facilities 

Annualized Cost per 

Model Plant, $/yr 

Total Nationwide 

Annualized Cost, $/yr 

Hard Chromium Electroplating

Small 12,000 442 $39,909 $17,640,000

Medium 35,000 142 $91,220 $12,953,000

Large 70,000 79 $169,301 $13,375,000

Decorative Chromium Electroplating

Small 12,000 59 $39,909 $2,355,000

Medium 24,000 22 $66,680 $1,467,000

Large 76,000 15 $182,686 $2,740,000

Chromium Anodizing

Small 12,000 18 $39,909 $718,000

Large 40,000 24 $102,374 $2,457,000

Total Nationwide Annualized Costs $53,705,000

 Sources without Existing Add-On Controls

 For existing chromium electroplating and anodizing sources that are not equipped with 

add-on controls, the same basic methodology was used as described in the previous paragraphs. 
10 

However, the 50 percent retrofit factor was excluded from the calculations, and the costs for 

installing an exhaust system and a primary control device were included. For the primary control 

device, it was assumed that a mesh pad mist eliminator (MPME) would be used. To estimate the 

cost of installing an exhaust system and MPME, the cost model developed for the NESHAP 

(Reference 2) was used and converted to 2009 dollars using the Consumer Price Index 

(Reference 7). The cost of a new HEPA filter system was added to these costs and a similar cost 

curve was developed. Figure 2 shows the resulting cost curve 

Figure 2. Annualized Cost Curve for Retrofitting new HEPA Filter on Existing 

Chromium Electroplating Source without Existing Add-on Controls. 

 The cost curve was used to estimate the cost per model plant, which was then multiplied 

by the number of plants nationwide. The resulting annualized cost to retrofit a new HEPA filter 

on all sources subject to the NESHAP without existing add-on controls was estimated to be 

$68.0 million. Table 14 shows a breakdown of the annualized costs for these sources. Table 15 

shows the combined annualized costs by model plant type and size for existing sources with addon controls and sources without add-on controls. Total nationwide annualized costs are 

estimated to be $121 million. Table 16 shows the same costs based on the source types and sizes 

specified in the NESHAP. 
11 

Table 14. Nationwide Annualized Costs for HEPA Retrofit - Sources without Add-on Controls 

Model 

Plant Size 

Exhaust Flow 

Rate, ACFM 

Number of 

Facilities 

Annualized Cost per 

Model Plant, $/yr 

Total Nationwide 

Annualized Cost, $/yr 

Hard Chromium Electroplating

Small 12,000 111 $54,981 $6,103,000

Medium 35,000 16 $138,286 $2,213,000

Large 70,000 0 $271,566 $0

Decorative Chromium Electroplating

Small 12,000 533 $55,524 $29,594,000

Medium 24,000 89 $98,627 $8,778,000

Large 76,000 22 $257,459 $5,664,000

Chromium Anodizing

Small 12,000 162 $55,525 $8,995,000

Large 40,000 36 $185,712 $6,686,000

Total Nationwide Annualized Costs $68,033,000

Table 15. Nationwide Annualized Costs for HEPA Retrofit - All Sources 

Model Plant Size Number of 

Facilities 

Total Nationwide 

Annualized Cost, $/yr 

Hard Chromium Electroplating

Small 553 $23,743,000 

Medium 158 $15,166,000 

Large 79 $13,375,000 

Decorative Chromium Electroplating

Small 592 $31,949,000 

Medium 111 $10,245,000 

Large 37 $8,404,000 

Chromium Anodizing

Small 180 $9,713,000 

Large 60 $9,143,000 

Total Nationwide Annualized Costs $121,738,000 

Table 16. Nationwide Annualized Costs for HEPA Retrofit - NESHAP Basis 

Facility Typea Number of 

Facilities 

Total Nationwide 

Annualized Cost, $/yr 

Large Hard Chromium 132 $18,425,000 

Small Hard Chromium 658 $33,859,000 

Decorative Chromium 740 $50,598,000 

Chromium Anodizing 240 $18,856,000 

Total 1,770 $121,738,000 a As defined in NESHAP. 
12 

IV. Cost Effectiveness for HEPA Filter Retrofit

 Table 16 presents the cost effectiveness for retrofitting HEPA filters on all existing tanks 

that are subject to the Chromium Electroplating NESHAP. The cost effectiveness ranges from 

$17.7 million per ton for large hard chromium electroplating plants to $944 million per ton for 

chromium anodizing plants. Overall cost effectiveness was estimated to be $78 million per ton. 

Table 16. Cost Effectiveness for HEPA Filter Retrofit 

Cost Effectiveness Facility Typea Emissions 

reductions, lbs/yr 

Annualized costs, 

$/yr $/lb $/ton 

Large Hard Chromium 2,087 $18,425,000 $8,800 $17,700,000

Small Hard Chromium 797 $33,859,000 $42,500 $84,900,000

Decorative Chromium 197 $50,598,000 $256,900 $513,900,000

Chromium Anodizing 40 $18,856,000 $472,400 $944,800,000

Total 3,121 $121,738,000 $39,000 $78,000,000 a

 As defined in NESHAP. 

V. References

1. Memorandum from R. Marinshaw, RTI International, to P. Mulrine, EPA/OAQPS. 

Estimated Number of Chromium Electroplating Plants. May 24, 2010. 

2. U.S. EPA. Chromium Emissions from Chromium Electroplating and Chromic Acid 

Anodizing Operations -- Background Information for Proposed Standards, Volume I (EPA 

453/R-93-030a). U.S. Environmental Protection Agency, Research Triangle Park, NC. July 

1993. 

3. U.S. EPA. Compilation of Air Pollutant Emission Factors, Volume 1, Stationary Sources, 

Section 12.20, Electroplating. U.S. Environmental Protection Agency, Research Triangle 

Park, NC. June 2006. 

4. U.S. EPA. EPA Air Pollution Control Cost Manual, EPA/ 452/B-02-001. U.S. 

Environmental Protection Agency, Research Triangle Park, NC 2002. 

5. South Coast Air Quality Management District. Final Socioeconomic Assessment for 

Proposed Amendments to Rule 1469 – Hexavalent Chromium Emissions from Chrome 

Plating and Chromic Acid Anodizing Operations and Proposed Rule 1426 – Emissions from 

Metal Finishing Operations. 2003. 

6. California Air Resources Board. Proposed Amendments to the Hexavalent Chromium 

Airborne Toxic Control Measure for Chrome Plating and Chromic Acid Anodizing 

Operations. 2003 

7. U.S. Department of Labor, Bureau of Labor Statistics. http://www.bls.gov/CPI/.