1

MEMORANDUM

DATE: October 25, 2011

SUBJECT: Emissions Data and Acute Risk Factor Used in Residual Risk Modeling: Pesticide Active

Ingredients, Polyether Polyols, and Group IV Polymers and Resins

FROM: Andrea Siefers, EPA

1.0 INTRODUCTION AND BACKGROUND

The purpose of this memorandum is to provide information on the Environmental Protection Agency (EPA) Risk and Technology Review (RTR) database used in estimating residual risk for the Pesticide Active Ingredients (PAI), Polyether Polyols (PEPOs), and Grou p IV Polymers and Resins (P&RIV) Maximum Achievable Control Technology (MACT) source categories. These MACTs cover only major sources.

Section 112 of the Clean Air Act (CAA) establishes a two

- stage regulatory process to address

emissions of hazardous air pollutants (HAPs) from stationary sources. In the first stage, section 112(d) requires the EPA to develop technology

- based standards for categories of industrial sources. In the second stage, known as the residual risk stage, section 112(f)(2) requires EPA to assess the health and environmental risks that remain after sources come into compliance with MACT. If additional risk reductions are necessary to protect public health with an ample margin of safety or to prevent adverse environmental effects, EPA mus t develop standards to address these remaining

risks.

2.0 DEVELOPMENT OF THE DATA SET USED IN RESIDUAL RISK MODELING

The 2005 National Air Toxics Assessment (NATA) National Emissions Inventory (NEI) data served as the starting point for this assessment. Usi ng the process MACT codes 1 , a list of facilities in the Pesticide Active Ingredients (PAI), Polyether Polyols (PEPOs), and Group IV Polymers and Resins (P&RIV) source categories (MACT codes: PAI

- 0911, PEPOs

- 1625, P&RIV

- 1302, 1318, 1331, 1328, 1338) was dev eloped. This facility list was used to create a subset of the NEI that contained facility wide emissions data for each facility in the source categories. Facility information was checked against compliance databases and permit information to ensure that th e facilities were subject to the relevant rules. Specific changes to data within each source category are discussed in 2.1, 2.2, and 2.3.

Upon the request of industry trade groups such as the American Chemistry Council (ACC) and the Society of Chemical Ma nufacturers & Affiliates (SOCMA), the 2005 NATA NEI data was voluntarily reviewed by industry for correctness of facility names, Source Classification Codes (SCC), MACT codes, emissions, location (latitude and longitude coordinates) and other modeling

para meters contained in the NEI. The proposal revisions were reviewed on a case by case basis and were accepted where appropriate. For these 3 source categories, revisions were made at 10 facilities.

1 Assigning data with MACT codes allows EPA to determine reductions attributable to the MACT program. The NEI associates MACT codes corresponding to MACT source categories with stationary major and area source data.2

EPA conducted an extensive review of the location coordinat es for all facilities in the 3 source categories. Locations were visually reviewed using Google Earth. Adjustments were made for approximately 40% of the coordinates based on these visual evaluations.

Stack and fugitive parameters that did not meet EPA Qu ality Assurance (QA) routines and standards were corrected. Permit data and input from industry was used to make area/major source designations. Finally, a standard QA of the modeling file was conducted.

Risks associated with facilities covered by the PAI, PEPOs, and P&RIV MACT standards were modeled using the resulting file. Specific revisions to each data set are discussed below.

2.1 DEVELOPMENT OF PAI DATA SET

The 2005 NATA NEI data had 18 facilities that were documented as having emissions

sources sub

ject to the PAI MACT. In the review of additional information, one facility, NEI11879 was determined to be permanently shut down. Therefore, there were 17 total facilities in the PAI source category. Supplemental emissions information within the source

cat egory was received from and accepted for NEI7211 and NEIMIB4942. Supplemental emissions information for sources not in the source category was also accepted for NEI11295 and NEI11906. Some emissions sources at NEI11906 were reassigned to the source categor y after input from the facility.

2.2 DEVELOPMENT OF PEPOs DATA SET

The 2005 NATA NEI data had 49 facilities that were documented as having emissions sources subject to the PEPOs MACT. In the review of additional information from industry, Title V permits, a nd permitting authorities, this list was reduced to 25 facilities. Supplemental emissions information within the source category was received from and accepted for NEI11906, NEI6013, and NEI8011. Some emissions sources at NEI11906 were reassigned out of th e source category after input from the facility. Supplemental emissions information for sources not in the source category was also accepted for NEI11295, NEI11906, NEI12483, NEI7296, and NEI8011. Additionally, updated stack parameters for

some emissions n ot in the source category were received and accepted for NEI56265.

2.3 DEVELOPMENT OF P&RIV DATA SET

The 2005 NATA NEI data had 48 facilities that were documented as having emissions sources subject to the P&RIV MACT. In the review of additional information from industry, Title V permits, and permitting authorities, this list was reduced to 32 facilities. Sources subject to P&RIV belong to one or more of the following 7 source categories of thermoplastics: acrylonitrile

- butadiene

- styrene resin (ABS), styrene

- acrylonitrile resin (SA), methyl methacrylate

- butadiene

- styrene resin (MBS), polystyrene resin (PS), polyethylene terephthalate resin (PET), methyl methacrylate acrylonitrile butadiene styrene resin (MABS), and nitrile resin (although only the first 5 of the 7 source categories currently have operating facilities in the U.S.). Supplemental emissions information was received for: NEI8510 (some emissions were reassigned out of the PET source category) and NEI11906 (some emissions were reassigned out of ABS a nd some were reassigned to SA). Emissions information for sources not in the source categories was also accepted for NEI11295 and NEI11906.3

3.0 ACUTE RISK

As outlined in Appendix B: Analysis of Data on Short

- Term Emission Rates Relative to Long

- Term

Emission Rates (Palma and Smith, 2009), short

- term emission rates can be estimated based on annual average rates in order to assess risk associated with acute exposure. For RTR rulemakings, unless more detailed information is available, it is generally assumed tha t the 1

- hour emission rate for each facility exceeds the annual average hourly emission rate by tenfold, and that this tenfold emission spike could coincide with worst

- case meteorological conditions and the presence of a human receptor at the facility boun dary. This method was developed as a means of screening for potentially significant acute exposures. This factor of ten was applied to all average annual hourly emission rates for a source, with two exceptions, described in 3.1 and 3.2. Changes to the data that were made after modeling was complete that affect the risk assessment are described in 4.0.

3.1 EMISSIONS FACTOR FOR ACUTE RISK BASED ON LONG

- TERM VOC EMISSIONS

Figure 1 describes the relationship of the ratio between the event emission rate to the lon g

term emission rate and the long

- term VOC releases. A conservative value of ten was chosen as the factor which to multiply all emissions in order to model acute risk (Palma and Smith, 2009). However, the relationship in Figure 1 suggests that the highest ratios were produced by facilities whose routine VOC emissions were relatively small and therefore facilities that have large VOC emissions also have a smaller ratio of event emission rate to long

- term emission rate. Based on this relationship, a factor of two was used for facilities that have long

- term VOC releases of greater than 200 lb/hr (or 876 tpy), as calculated from the 2005 NEI. A list of facilities where we used the factor of two instead of ten is provided in Appendix 7 of the risk assessment docu ment.4

Figure 1

. Relationship between ratio of event to duration emission rate and total amount emitted during the event. (Palma and Smith, 2009)

3.2 EMISSIONS FACTOR FOR ACUTE RISK BASED ON PROCESS KNOWLEDGE

A factor of two for acute risk was chosen for emissions from equipment leaks. However, this factor was chosen after most of the risk assessment was already complete and was therefore only applied to several facilities showing the highest risk. The factor of two was chosen

bec ause emissions from equipment leaks are inherently different from other emission sources at chemical manufacturing facilities. While we believe that it is possible that worst

- case short

- term emission episodes from sources such as process vents, stacks, or flares may be as high as ten times the annual average due to events such as upsets or process flow variability, this does not apply to equipment leaks. Equipment leaks are not affected acutely by variable flow in a system and thus cannot emit in the same w ay as aforementioned emission sources during a large

- scale upset. If an event causing a pressure increase occurred in a process stream where a leak was present, we would not expect the toxic vapor analyzer (TVA) used as a part of EPA Method 21 to give a hi gher reading because the concentration read by the TVA is only a function of the composition of the process stream. The emissions estimate is based on this concentration measurement and has already incorporated variability, as

discussed below. While releas es from emission sources such as pressure relief devices are an acute risk issue because they are generally high concentration releases for short durations, equipment leaks pose more of a chronic risk issue because they are generally a small

emission rate over a long period of time. Therefore, we do not believe that emissions from equipment leaks pose a large acute risk.

Additionally, a large uncertainty factor has already been incorporated into the emission rate estimates from equipment leaks and we have determined that it was not appropriate to add another level of uncertainty to this. To calculate emissions from equipment leaks in this industry, screening is conducted on a regular basis and when a leak is measured using EPA5

Method 21, a predetermined emi ssion factor from EPA’s Protocol for Equipment Leak

Emission Estimates document is applied. When these emission rates for equipment leaks were developed, EPA used data from a number of different studies of bagged samples at petroleum and synthetic organic chemical manufacturing facilities. In these studies, EPA

measured for leaks using EPA Method 21 and where leaks were found, the concentration was recorded, the leak was bagged, and an estimate of the mass emission rate was calculated from the bagged sample. From the results of these studies, mass emission rates were found to vary up to five orders of magnitude for a given EPA Method 21 concentration reading. A correlation was developed based on these results, which was inherently biased towards higher emission rates. A more detailed discussion on how these correlations were d eveloped can be found in Appendix B of EPA’s Protocol for Equipment Leak Emission Estimates document. Based on this information, we do not believe it is appropriate to add yet another order of magnitude of uncertainty to emissions from equipment leaks, and that a factor of two is more appropriate. A list of facilities where we used the factor of two instead of ten is provided in Appendix 7 of the risk assessment document.

4.0 DATA REVISIONS AFFECTING RISK ANALYSIS

Some revisions to the data set were made pos t

- modeling after receiving additional information from other regulatory entities or industry. Part of these changes reflected facilities which were shut down or no longer operating. Other information received reflected changes in the source category of cer tain emission points or that a specific process unit had been shut down within a facility. These changes were not made directly to the modeling file, as they would cause changes in the modeling itself. Instead, this information can be used qualitatively to understand the risk results. This information is detailed below:

NEINC0595 is not in the PEPOs source category NEI12483 is not in the PEPOs source category

NEI41302 has been shut down NEI43310 has ceased operations The hexachlorobenzene emission point at NEI11906 should actually be attributed to the PAI source category and not PEPOs NEI45591 has closed the PET production process and acetaldehyde emissions are almost

zero Phosgene emissions in the PAI source category at NEI 8596 are incorrect and should re flect one fugitive emission point and one stack emission point, both of 0.01 tpy, totaling 0.02 tpy The arsenic emission point at NEIWV0390007 is not in the PAI source category

REFERENCES

Blacksmith, J.R., et al. (Radian Corporation.) Problem

- Oriented Report: Frequency of Leak Occurrence for Fittings in Synthetic Organic Chemical Plant Process Units . Prepared for U.S. Environmental Protection Agency. Research Triangle Park, NC. Publication No. EPA

- 600/2

- 81

- 003. September 1980.

Development of Fugitive E mission Factors and Emission Profiles for Petroleum Marketing Terminals

. Volumes I and II, API 4588, Radian Corporation, Prepared for American Petroleum Institute,

1993.6

DuBose, D.A., J.I. Steinmetz, and G.E. Harris (Radian Corporation). Frequency of Leak Occurrence and Emission Factors for Natural Gas Liquid Plants . Final Report. Prepared for U.S. Environmental Protection Agency. Research Triangle Park, NC. EMB Report No. 80

- FOL

- 1. July 1982.

Emission Factors for Oil and Gas Production Operations , API 46 15, Star Environmental, Prepared for American Petroleum Institute, 1995.

Fugitive Hydrocarbon Emissions from Oil and Gas Production Operations , API 4589, Star Environmental, Prepared for American Petroleum Institute, 1993.

Langley, G.J. and R.G. Wetherho ld. (Radian Corporation.) Evaluation of Maintenance for Fugitive VOC

Emissions Control . Prepared for U.S. Environmental Protection Agency. Research Triangle Park,

NC. Publication No. EPA

- 600/S2

- 81

- 080. May 1981.

Letter from Robert Strieter, API, to David Markwordt, U.S. EPA, regarding the submittal of gasoline distribution facility fugitive equipment screening data. April 26, 1994.

Palma, Ted and Roy Smith. Appendix B: Analysis of Data on Short

- Term Emission Rates Relative to Long

- Term Emission Rates . Ris k and Technology Review (RTR) Risk Assessment Methodologies. Prepared for U.S. Environmental Protection Agency. Research Triangle Park,

NC. Publication No. EPA

- 452/R

- 09

- 006. June 2009.

Radian Corporation. Assessment of Atmospheric Emissions from Petroleum Refining . Volume 4. Appendices C, D, E. Prepared for U.S. Environmental Protection Agency. Research Triangle Park, NC. Publication No. EPA

- 600/2

- 80

- 075d. July 1980.

Wetherhold, R.G., L.P. Provost, and C.D. Smith (Radian Corporation). Assessment of Atmosp heric Emissions from Petroleum Refining . Volume 3. Appendix B. Prepared for U.S. Environmental Protection Agency. Research Triangle Park, NC. Publication No. EPA

- 600/2

- 80

- 075c. April

1980.

1993 Study of Refinery Fugitive Emissions from Equipment Leaks . Vo lumes I, II, and III, Radian DCN

No. 93

- 209

- 081

- 02, Radian Corporation, Prepared for Western States Petroleum Association, Glendale, CA, and American Petroleum Institute, Washington, D.C., 1994.