To: Susan Fairchild , EPA From: Dave Reeves , RTI

Project Files Date: October 15 , 201 4

Re: Mineral Wool RTR Ample M argin of S afety (AMOS)

– A nalysis and P roposed C ontrols

I. Introduction

The purpose of this memorandum is to present information used in the ample margin of safety analysis for the U.S. Environmental Protection Agency’s (EPA’s) residual risk review of the national emission standards for hazardous air pollutants (NESHAP) for the Mineral Wool Production (40 CF R part 63, subpart DDD ) i n accordance with section 112(f)(2) of the Clean Air Act (CAA).

Mineral wool is an insulation product which is made by melting layers of minerals and mineral products such as rock, slag, glass cullet and coke in a cupola, fiberizing the molten mineral, c ollecting the fiber as a layer that can be cut and formed into various products for fire protection and noise attenuation in commercial, institutional and industrial buildings. When a binder is used, it is applied at the fiberization process. The three pro cess 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 mineral wool building product s must meet rigid product safety specifications

. For more information on the mineral wool production
process, see preamble discussion in the November 25, 2011 proposal (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 i n this process is the determination of acceptable risk. Under this first step the EPA conducted an information collection request ( ICR) that included all mineral wool production facilities currently operating in the US. The ICR 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 subset . Test results were typically presented as three test runs and provided in units of mass of pollutant 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 infor mation on each facility, process, process equipment, control equipment, costs, and HAP emissions. The EPA then used the t est data to populate the mineral wool residual risk modeling file. The risk assessment which evaluated both actual and allowable emissi ons can be found in the October 2014 Draft Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories in the Docket. Generally, if risks are found to exceed 100

- in

- 1 million, we consider this unacceptable and act to reduce risk to acceptable 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; for the mineral wool produ ction source category, risks were found acceptable at 1 0

- in

- 1 million.

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 risk s and other health information considered in the acceptability determination. Beyond that information, additional factors relating to the appropriate level of control are also considered, including costs and economic impacts of controls, technological feas ibility, uncertainties and any other relevant factors. Considering all of these factors, the agency will establish the standard at alevel that provides an ample margin of safety to protect the public health, as required by CAA

section 112(f). The EPA prop os ed in the April 15, 2013 Federal Register that risks from the mineral w ool production source category are acceptable at 10

- in

- 1 million (78 FR 22370)

. D etails of the analysis can be found in the October 2014 Draft Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories. For the ample margin of safety determination, the EPA referred to the conclusions from the technology review (see docket item 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 production processes and that the proposed subpart DDD standard s protect public health with an ample margi n of safety

. II. Identification of Subpart DDD Risk Driver HAPs and Processes

The November 2011 , February 2013, and October 2014 Draft Residual Risk Assessment for the Mineral Wool Production and Wool Fiberglass Manufacturing Source Categories were base d on actual measured emissions currently emitted by industry. The assessment identified the

o ne mineral wool facili ty with the highest risk of an MIR of 10

- in

- 1 million due to emissions of formaldehyde

. Approximately 14 people were estimated to have cancer risk greater than or equal to 10

- in

- 1 million and 10,300 people at cancer risks above 1

- in

- 1 million as a result of emissions. The assessment estimated chronic non cancer risks (HI) at 0.1 and a maximum acute hazard quotient (HQ) of 20. F ormaldehyde was also the driver for both HQ and HI. Three of the seven

m ineral 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 com posed of a phenol

- formaldehyde resin ) . The specific processes of a bonded mineral wool production line that emit formaldehyde are curing and collection

. Therefore, the ample margin of safety analysis discussed for the remainder of this memorandum focuses on th is risk

driver HAP and the curing and collection processes.

III. Ample Margin of Safety Analysis

Several potential measures or options for reducing formaldehyde emission s from bonded lines were evaluated. C urrent controls at curing and forming ope rations on bonded lines were reviewed. A ll bonded lines are equipped with HAP controls (i.e., incinerator, RTO, or scrubber) and

, as stated in the technology review memo ( d ocket i tem 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 mineral wool products made this option technically infeasible

.

T he original Mineral Wool NESHAP did not regulate the collection chamber of bonded lines. E missions from th e collection process and controls were evaluated . Most collection
processes a re routed to a mechanical filter for PM control

. The cost estimates for installation of additional HAP controls at the collection process were evaluated and it was found that controls capable of handl ing the high volume air flows characteristic of most collection processes would be cost prohibitive. A cost estim ate for an incinerator large enough to handle th is air flow in theexhaust 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 maintenance expenses were estimated at $1. 1 million. Assuming addi tio n of incineration to the collection 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 insignificant impact on risk reductions.

In general, incinerators and oxidizers are most effective on high concentration organic compounds. When VOC (including formaldehyde) are in dilute quantity, combustion efficiency is greatly reduced which could result in lower formaldehyde r eductions than current operations. The po tential re

- routing exhaust from the collection process through existing incineration or other control equipment was considered. It was found that existing f aci lities do not have equipment with sufficient capacity to handle the additional 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 Margin of Safety Analysis.

Option Feasibility Annualized Cost ($M) Formaldehyde

Reduction (ton/yr) Phaseout of Phenol

Formaldehyde 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 equip ment does not have additional air flow capacity --- ---

Of the seven existing mineral wool production facilities, three operate bonded lines in association with the collection process es , which have been termed ‘combined collection and curing’

. Each of the combined collection and curing designs (e.g. , drum, vertical, and ho rizontal ) were reviewed, and d ue to significant differences between each process design

, emission limits for phenol, formaldehyde and methanol were 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 line s were reviewed. These 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 reductio n. Considering cost and technical feasibility, no feasible options for increasing the ample margin of safety were identified for mineral wool production f acilities.