MEMORANDUM

Date: June 18, 2015

Subject: Mineral Wool RTR Ample Margin of Safety – Analysis and Proposed Controls

From: Susan Fairchild, EPA/OAQPS/SPPD/MMG

To: EPA Air Docket EPA-HQ-OAR-2010-1041

I. Introduction

The purpose of this memorandum is to present information use d in the ample margin of safety (AMOS) analysis for the U.S. Environmental Prot ection Agency’s (EPA’s) residual risk

review of the national emission standards for hazardous air pollutants (NESHAP) for the Mineral Wool Production (40 CFR part 63, subpart DDD) in accordance with section 112(f)(2) of the Clean Air Act (CAA).

Mineral wool is an insulation product which is made by melt ing layers of minerals and mineral products such as rock, slag, glass cullet and coke i n a cupola, fiberizing the molten mineral, collecting the fiber as a layer that can be c ut and formed into various products for fire protection and noise attenuation in commercial, instituti onal and industrial buildings. When a binder is used, it is applied at the fiberization process. T he three process lines in the mineral wool industry that manufacture a bonded product use a phenol /formaldehyde-based binder which is cured to harden, providing structural strength. The minera l wool building products must meet rigid product safety specifications. For more information on the mineral wool production process, see preamble discussion in the November 25, 2011 pro posal (76 FR 72775).

Section 112(f)(2) of the CAA refers to a two-step process for developing standards to address residual risk. The first step in this process is t he determination of acceptable risk. Under this first step the EPA conducted an information collecti on request ( ICR) that included all mineral wool production facilities currently operating in the US. The IC R was voluntary and allowed companies to perform HAP emissions testing on a subset of facility operations, if the facilities were able to demonstrate that the subset was representative of the untested s ubset. Test results were typically presented as three test runs and provided in units of mass of pol lutant per mass of production (e.g., lbs of HAP/ton of glass). The ICR responses from all the facilities were compiled in the project database and included information on each facility, proces s, process equipment, control equipment, costs, and HAP emissions. The EPA then used the test data to populate the mineral wool residual risk modeling file. The final risk assessment which e valuated both actual and MACT

allowable emissions can be found in the document titled Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories in Support of the June

2015 Final Rule in the Docket. Generally, if risks are found to exceed 100-in-1 million, we consider this unacceptable and act to reduce risk to acceptabl e levels by requiring emission reductions of the pollutants responsible for the risk (i .e., the ‘risk drivers’). If risk is found to be below 100-in-1 million, we consider risk to be acceptable; f or the mineral wool production source category, risks were found acceptable at 10-in-1 mi llion.The second step of Section 112(f)(2) provides for an ample margin of safety (AMOS) to

protect public health. For the AMOS determination, the EPA again considers all of the health

risks and other health information considered in the acc eptability determination. Beyond that information, additional factors relating to the appropri ate level of control are also considered, including costs and economic impacts of controls, technol ogical feasibility, uncertainties and any other relevant factors. Considering all of these facto rs, the agency will establish the standard at a level that provides an ample margin of safety to protec t the public health, as required by CAA section 112(f). The EPA proposed in the April 15, 2013 Federal R egister that risks from the mineral wool production source category are acceptable at 10-in-1 million (78 FR 22370). Details of the analysis can be found in the document titled Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories in Support of the

June 2015 Final Rule. For the ample margin of safety determination, the EPA referred to the conclusions from the technology review (see docket ite m EPA-HQ-OAR-2010-1041-0111) performed for CAA section 112(d)(6) that no technologies ( beyond those already in place) were identified for reducing HAP emissions from mineral wood pr oduction processes and that the proposed subpart DDD standards protect public health with an a mple margin of safety.

II. Identification of Subpart DDD Risk Driver HAPs and Pr ocesses

The risk assessment identified the one mineral wool fac ility with the highest risk of an MIR of 10-in-1 million due to emissions of formaldehyde. Appr oximately 1 person was estimated to have cancer risk greater than or equal to 10-in -1 million and 11,600 people at cancer

risks above 1-in-1 million as a result of emissions. T he assessment estimated chronic non cancer risks (HI) at 0.1 and a maximum acute hazard quotient (HQ) o f 20. Formaldehyde was also the driver for both HQ and HI. Three of the seven mineral wool facilities emit the majority of formaldehyde emissions from bonded lines (that is, the production of bonded products which involve the application of a HAP-based binder, typically composed of a phenol-formaldehyde resin). The specific processes of a bonded mineral wool pr oduction line that emit formaldehyde are curing and collection. Therefore, the ample margi n of safety analysis discussed for the

remainder of this memorandum focuses on this risk-driver HA P and the curing and collection

processes.

III. Ample Margin of Safety Analysis

Several potential measures or options for reducing formal dehyde emissions from bonded lines were evaluated. Current controls at curing and formi ng operations on bonded lines were reviewed. All bonded lines are equipped with HAP controls (i .e., incinerator, RTO, or scrubber) and, as stated in the technology review memo (docket ite m EPA-HQ-OAR-2010-1041-0111), no new technologies (beyond those already in place) were found.

A pollution prevention option (the use of non-HAP binders) was considered, but it was found that product (performance) specifications of minera l wool products made this option technically infeasible.

The original Mineral Wool NESHAP did not regulate the co llection chamber of bonded lines. Emissions from the collection process and contr ols were evaluated. Most collectionprocesses are routed to a mechanical filter for PM cont rol. The cost estimates for installation of

additional HAP controls at the collection process wer e evaluated and it was found that controls capable of handling the high volume air flows characteri stic of most collection processes would be cost prohibitive. A cost estimate for an incinerato r large enough to handle this air flow in the exhaust of the collection chamber was $1.8 million, with an additional estimated $0.4 million for a pre-filter and exhaust stack. Annual operating and maintenan ce expenses were estimated at $1.1 million. Assuming addition of incineration to the col lection process would control formaldehyde emissions by 98 percent, an estimated industry -wide reduction in formaldehyde is less than 1 ton per year. This results in an insignifica nt impact on risk reductions.

In general, incinerators and oxidizers are most effectiv e on high concentration organic compounds. When VOC (including formaldehyde) are in dilute qua ntity, combustion efficiency is greatly reduced which could result in lower formaldehyde reductions than current operations. The potential re-routing exhaust from the collection pro cess through existing incineration or other control equipment was considered. It was found that existing facilities do not have equipment with sufficient capacity to handle the addit ional flow and pollutant loading of the collection chamber and therefore this option would not be technically feasible (see Section 112(d)(6) Technology Review for Mineral Wool NESHAP , docket item EPA-HQ-OAR-2010- 1041-0111). Table 1 summarizes the above information for the AMOS options that were

considered.Table 1. Options Considered for the Mineral Wool Ample M argin of Safety Analysis.

Option Feasibility Annualized Cost ($M) Formaldehyde

Reduction (ton/yr)

Phaseout of PhenolFormaldehyde Binders Infeasible- building product safety specifications --- ---

Add on RTO to baghouse High air flow reduces effectiveness of RTO,

increases cost $1.1M <1

Reroute curing/collection exhaust to cupola Infeasible – existing equipment does not have additional air flow capacity --- ---

Of the seven existing mineral wool production facilities, three operate bonded lines in association with the collection processes, which have been termed ‘combined collection and curing’. Each of the combined collection and curing designs (e.g., drum, vertical, and horizontal) were reviewed, and due to significant differen ces between each process design, emission limits for phenol, formaldehyde and methanol wer e proposed under these three subcategories according to design (see Revised Technical Approach for Mineral Wool MACT

Floor Calculations dated September 26, 2014 in docket EPA-HQ-OAR-2010-1041).

IV. Conclusions

The health risks associated with formaldehyde emissions from curing, forming, and collection processes at bonded lines were reviewed. The se formaldehyde-emitting processes were the focus of the ample margin of safety analysis because control measures applied to these processes offer the greatest potential for risk reduction . Considering cost and technical feasibility, no feasible options for increasing the am ple margin of safety were identified for mineral wool production facilities.