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**MEMORANDUM TO:**  Anne Pope, EPA **FROM:** Susan Fairchild, Project Lead **DATE:** September 1 6 , 201 1 **SUBJECT:** Emissions Data Used in Residual Risk Modeling for Mineral Wool

Production The purpose of this memorandum is to provide information on the RTR database used in estimating residual risk for the Mineral Wool Production Maximum Achievable Control Technology

( MACT ) source category
. **BACKGROUND** 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 Environmental Protection Agency (EPA) to develop technology

- based standards for c ategories of industrial sources. In the second sta g e, known as the residual risk stage, section 112(f)(2) requires EPA to assess the hea l th 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 must develop standards to address these remaining (“residual”) risks. As part of this second stage, data w ere gathered to assess the residual risks from the Mineral Wool Production MACT source category
. **EMISSIONS DATA USED IN RESIDUAL RISK MODELING** I. In formation Collection Request (ICR) A voluntary

I CR was sent out in March 2010 to seven mineral wool production facilitie s currentl y operating in the U S. I CR responses from all the facilities were compiled in the project database and included information on facility process es , equipment, control devices , costs, and HAP emissions. Facility

- specific production rate information was also included and was claimed as confidential business information (CBI), which resulted in much of the project database being treated as CBI. II. Emissions Testing Mineral wool facilities were asked to supply test data on cupolas, curing ovens, and collection operations. All facilities supplied existing test data, new test data conducted in 2010, or a combination of these for one or more emission unit (s)

. Six of the mineral wool production facilities conducted “new” emissions testing in 2010. The one facility that did2

no t conduct an y recent (2010) emissions testing was Amerrock Products LP (Amerrock) located in Nolanville, TX. The test results were typically presented as an average of three test runs and provided in units of mass of pollutant per mass of production (e.g. , pounds ( lbs ) of HAP/ton of melt). Both new and existing test results were used to calculate average emission rates for emission sources . The number of data sets varied depending on the pollutant, emission source, and the ty

pe of product being produced at the facility (one to four datasets were used for a pollutant at a specific source). III. Source

- Specific Emissions Using the production rates that each facility provided in their I CR response and the emission rates from the emission testing, annual emissi ons (tpy) for each pollutant were calculated for each emission source. The sources modeled in the risk anal ysis are listed as follows.

o Unbonded lines: Cupolas o Bonded lines: Cupolas, Curing Ovens, Collection, and Cooling. As previously

mentioned, the p ol lutants and emission sources tested b y facilities varied. For facilities that did not perform testing on a particular pollutant at a specified source, an emission rate (lb/ton melt) for each missing pollutant was calculated from a similar source at another facility . I f there was more than one similar source that had emission rate data, the average emission rate of all the similar sources was used. This emission rate was then multiplied by

the production rate of the facility with the missing data

. T esting parameters (velocity , temperature, etc.) of the similar source were also used (or the average if there was more than one similar source) to populate the data set for each facility

. The s tack parameters (height, diameter, etc.) were all taken from facility I C R responses
– none of them were estimated or based on similar sources

. 3a
. Cupola Emissions Pollutants estimated for cupolas include : HAP Metals, Hydrogen Chloride ( HCl ) , Hydrogen Flu oride ( HF ) , Hexavalent Chromium ( Cr+6 ) , Carbon ylSulfide ( COS ) , Mercury ( Hg ). In order to calculate an average emission rates (lb/ton melt) from cupolas for each pollutant, the control device had to be taken in account. Cupolas were divided into two categories:

 Cupolas with baghouse control  Cupolas with baghouse and incinerator control3

Therefore, if a cupola that only has baghouse control was not tested for a certain pollutant, an average emission rate (lb/ton melt) for that pollutant was calculated using test results from other cupolas that also only have baghouse c ontrol.

 Amerrock

- The Amerrock facility did not do an y recent (2010) emissions testing and has two cupolas routed to one stack with a scrubber and a baghouse (fabric filter) control. Since they are the only

facility with that configuration and we did n ot have enough test data to estimate the control efficiency of the scrubber for all the pollutants, the average emission rate (lb/ton melt) of cupolas with just a baghouse control were conservativel y used and multiplied by

Amerrock’s total plant production capacity (tons of melt) to account for emissions from both cupolas.

 Thermafiber

- The Thermafiber facility has two cupolas that are not routed together; they

tested each cupola separatel y for almost all pollutants. A few pollutants were tested at one cupola but not the other. When this was the case, the emission rate (lb/ton melt) of the cupola tested was used along with the production capacity

of the cupola with the missing pollutant to get annual emissions. 3 b. Curing Oven, Cooling, and Collection Emissions Pollutants estimated for Curing/Collection include : Formaldeh yd e, Phenol, Methanol. Curing, cooling, and collection stack configurations for each facility that produces bonded material (three facilities) are different (some have the exhaust/emi ssions routed together and some do not). The onl y emissions that had to be estimated under Curing/Cooling/Collection were for two pollutants at Thermafiber’s curing oven. Thermafiber has curing operations that are routed to an independent stack. Rockwool is the only other facility

that also has curing operations routed to an stack; therefore , the emission rate (lb/ton melt) for Rockwool w as used along with Thermafiber’s production capacity from the ICR to estimate annual emissions for the missing pollutants. IV
. Chromium and Mercury Speciation Consistent with the HAP list in the Clean Air Act, metals such as chromium and mercury may be reported in the ICR under different names, including chromium, chromium compounds, mercury , and mercury compounds. Faciliti es that submitted chromium emissions data reported it as total chromium and hexavalent chromium emissions. Hexavalent chromium emissions were not speciated further and were modeled as chromium VI. Total chromium was speciated to Chromium III b y subtracting chromium VIemissions from total chromium. In some cases chromium VI emissions were larger than total chromium. For these circumstances it was assumed that all chromium emissions were hexavalent chromium and chromium III emissions were “ 0 ” . Facilities th at submitted mercury

data provided it as total mercury ; the following table summarizes the speciation factors that were applied to mercury emissions.4

POLLUTANT_CODE POLLUTANT_DESCRIPTION HAP_CATEGORY_NAME % of total 200 Elemental Gaseous Mercury Mercury Compounds 80% 202 Particulate Divalent Mercury Mercury Compounds 10% 201 Gaseous Divalent Mercury Mercury Compounds 10%
V. Emission Process Group Assignment In order to assign risk results to specific operations within mineral wool facilities, Emission Process Groups are assigned to SCCs. There are onl y three ty pes of emission process groups for mineral wool production: 1) cupolas , 2) collection , and 3) curin g operations . Combinations of these processes were used as emission process groups when one or more of these processes shared a common stack. VI
. QA/QC Companies were sent aerial views of each plant and asked to label and provide coordinates for each stack. They were also asked to review their stack configurations for each emission unit. All wool fiberglass facilities answered the request and provided labeled aerial views along with coordinates. EPA also conducted an extensive review of the locational coordi nates for all facilities in the wool fiberglass source category

. Locations were visually

reviewed using Google Earth or ArcExplorer. Adjustments were made for coordinates based on these visual evaluations if necessary

. Emissions data, stack parameters, and facility information was also reviewed for each unit and pollutant at a given plant. Production rates for each unit were checked with the responses provided in the I CR. After risk modeling was conducted, it was discovered that one test run submitted by a facility was not performed during normal operating conditions and that the production rate for another facility was interpreted incorrectl y and did not capture production for the facility as a whole. The data set file was corrected and risks associated with the changed source s w ere remodeled. VII. Allowable Emissions In order to evaluate the risk associated with the highest allowable emissions for all air pollutants from the Mineral Wool Production source category , we estimated the allowable emissions based on formaldeh yde. Formaldeh yde was considered the most important HAP emitted from this source category based on our screening level risk assessment and the HAP for which we had the most data. To estimate emissions at the MACT

- allowable level from stacks, we estimated the actual formaldeh yde emission rates at curing and collection sources for facilities that operate bonded lines. These emission rates were compared to the m aximum allowed by the existing MACT standard ((i.e., 0.06 pounds of formaldeh yd e per ton of melt) from all curing ovens. Based on this analy sis, we conclude d that all facilities are emitting formaldehyde at emission rates lower than5

allowable. T he estimate d actual formaldehyde emission rates were approximately 2 times lower than allowable emissions. The other facilities producing nonbonded product did not report an y formaldeh yd e, phenol, or methanol emissions. MACT

- allowable emissions were conservatively estimated to be 3 times the actual emissions for all pollutants in the Mineral Wool Production category to account for control device efficiencies at the different facilities . Therefore, to develop the MACT

allowable emissions the actual stack emissions were multiplied by 3 for each Mineral Wool Production facility

.