# DRAFT

Date: May 25, 2010

Subject: Model Plant Data Used to Estimate Ri sk from Chromium Electroplating Sources Emission Standards Technical Suppor t and Post Promulgation Activities EPA Contract No. EP-D-06-118; EPA Work Assignment No. 4-6 RTI Project No. 0210426.004.006

From: Richard Marinshaw

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

The purpose of this memorandum is to provide the basis for the model plant parameter data used to assess the risk from chromium electroplating facilities subject to the national emission standards for hazardous air pollutants (N ESHAP) for Hard and Decorative Chromium Electroplating and for Chromium Anodizing Tanks (40 CFR 63, subpart N). Section I of this memorandum provides background information on th e decision to use model plant data, and Section II provides the basis for the data modeled.

I. Background

There are estimated to be about 1,770 chromium electroplating plants in operation in the U.S. 1 This total includes plants that perfor m hard chromium elec troplating, decorative chromium electroplating, and chromium anodizin g. However, emissions data were available, through the NEI database and othe r plant-specific information on file, for only about 120 plants when the initial risk modeling for chromium el ectroplating was performe d. Table 1 shows a breakdown of the number of plants by process t ype and the number with available data.

Table 1. Availability of Data on Emissi ons from Chromium Electroplating Plants a

Process Estimated No. of plants No. of plants with available emissions data Hard chromium electroplating 790 38

Decorative chromium electroplating 740 81

Chromium anodizing 240 5 Total 1,770 124

a Reference 1.

In order to better characterize the risk associated with emissions from chromium electroplating sources na tionwide, the decision was made in July-August of 2009 to model all the plants with known addresses using model plant emissions data. The following section describes the model plant data used and the basis for the data.2

II. Basis for Model Plant Data

The first step in this process was to assign em issions to each type of plant to be modeled. For the NESHAP, eight model plants had been de veloped: three plants for hard chromium (small, medium, large), three plants for decora tive chromium (small, me dium, large), and two plants for anodizing (small, large). 2 The model plants were base d on data collected from more than 100 facilities that responded to an info rmation collection request for the chromium electroplating industry. Data from site visits and other informati on also were used in developing the model plants. A complete description of the model plants developed for the NESHAP is provided in Reference 2, the Background Info rmation Document for the proposed NESHAP (Chromium Electroplating BID).

The Chromium Electroplating BID include d estimates of uncontrolled chromium emissions for each type of model plant. Cont rolled emissions were estimated by applying the control efficiencies developed for the NESHAP. For hard chromium el ectroplating, the control efficiency was based on the performance of co mposite mesh pads; for decorative chromium electroplating and for chromium anodizing the c ontrol efficiency was based on the performance of wetting agent fume suppressants. Table 2 shows the estimated uncontrolled and controlled emissions for each type of model plant.

Table 2. Chromium Electroplating Model Plant Emissions a

Chromium Compound Emissions, lbs/yr

Process Control level Small Medium Large Uncontrolled (0%) 110 926 3,530 Hard chromium Controlled (99%) 1.1 9.26 35.3 Uncontrolled (0%) 13 53 530 Decorative chromium Controlled (99.5%) 0.065 0.27 2.65 Uncontrolled (0%) 7.2 88 Chromium anodizing Controlled (99.5%) 0.036 0.44

a Reference 2.

To model worst-case emissions , consideration was given to modeling all plants using data for the "large" size of model plant for each t ype of process. Based on the available data on actual emissions, this approach seemed reasonab le for decorative chromium electroplating and for chromium anodizing. However, that was no t the case for hard chromium electroplating. Based on data provided in the permit applicati on for the Empire Hard Chrome, Kostner Avenue plant, located in Chicago, RTI estimated emi ssions of chromium compounds at the emission limit for typical operating hours to be about 31 pounds per year (lbs/yr). Becau se this facility is supposedly the largest hard chromium plant in the U.S., it serves as an upper bound for emissions from hard chromium electroplating. Ho wever, the estimated emissions for the Empire Hard Chrome plant is less than the estimated emissions for a large hard chromium model plant (35.3 lbs/yr). As a result, it was considered un reasonable to use the large model plant emissions value to estimate emissions for all hard chromium electroplating plants na tionwide. Instead, the3

decision was made to model hard chromium plants with the emission rate for a medium-size hard chromium model plant (9.26 lbs/yr). The fina l emissions rates modeled were as follows:

Hard chromium electroplating: 9.26 lbs/yr Decorative chromium electroplating: 2.65 lbs/yr Chromium anodizing: 0.44 lbs/yr

Based on actual emissions data available, these emission rates seem reasonable for representing worst-case emissions. For hard chromium electroplating, the available data are generally on the order of a few pounds per year. For decorative chromium electroplating, actual data indicate emissions are gene rally less than 1 lb/yr. No actual data were available for chromium anodizing, but those facili ties tend to be smaller, and ther e is no reason to believe that the large model plant emissions of 0.44 lbs/yr would not be a good estimate of worst-case emissions.

The next step was to assign a model plant and emissions to each of the 1,629 plants with complete addresses listed in the Electroplating Database. 3 However, there was information on the type of electroplating performed for only about half of the plants. Furthermore, the available information indicated that some plants pe rformed more than one type of chromium electroplating. Therefore, to be consistent with the worst- case approach, the following assumptions were made:

• All plants that performed hard chromium electroplating in combination with decorative chromium or chromium anodizing would be mo deled as hard chromium electroplating.

• All plants that performed decorative chromium electroplating in combination with chromium anodizing would be modeled as decorative chromium electroplating.

• All plants for which the process was unknow n would be modeled as hard chromium electroplating.

Table 3 summarizes the final assignment of em issions for each type of plant. The table also shows the maximum achievable control t echnology (MACT) codes us ed in the modeling.

Table 3. Modeled Emissions by Chromium Electroplating Process Type

Process MACT Code Number of plants Emissions, lbs/yr Hard chromium electroplating only 1615 301 9.26 Decorative chromium electroplating only 1610 326 2.65 Chromium anodizing only 1607 73 0.44 Hard and decorative and/or chromium anodizing 1615M 115 9.26 Decorative chromium and chromium anodizing 1610M 11 2.65 Unknown type of electropl ating process 1615D 803 9.26 Total 1,6294

Other data needed for the risk modeling file included certain stack parameters. Table 4 summarizes the values used in the modeling for these parameters, which are also based on the model plants developed for the NESHAP, as docum ented in the Chromium Electroplating BID.

Table 4. Chromium Electroplating Model Pl ant Parameters Used for Risk Modeling a

Plant type Stack Height

(ft) Exhaust Gas Temperature (°F) Stack Diameter (ft) Exhaust Gas Velocity (ft/sec) Orientation of Emission Point Hard chromium electroplating only 30 80 3.8 50 Vertical

Decorative chromium electroplating only 17 80 4 29 Horizontal Chromium anodizing only 17 80 4 29 Horizontal

Hard and decorative and/or chromium anodizing 30 80 3.8 50 Vertical

Decorative chromium and chromium anodizing 17 80 4 29 Horizontal Unknown type of electroplating process 30 80 3.8 50 Vertical

a Reference 2.

III. References

1. Memorandum from R. Marinshaw, RTI Inte rnational, to P. Mulrine, EPA/OAQPS. Estimated Number of Chromium Electroplating Plants. May 24, 2010.

2. Chromium Emissions from Chromium El ectroplating and Chromic Acid Anodizing Operations -- Background Information for Proposed Standards, Volume I (EPA 453/R93-030a). U.S. EPA, Office of Air Qual ity Planning and Standards. July 1993.

3. Electroplating Database. RTI International. 2010.