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MEMORANDUM

Date: December 3, 2013

Subject: Cost Impacts of Pressure Relief Device Monitoring for Acrylic and Modacrylic 

Fibers Production, Polycarbonate Production, and Amino/Phenolic Resins 

Production Source Categories

From: Tanya Parise and Lesley Stobert, EC/R Incorporated

To: Nick Parsons, EPA/OAQPS/SPPD

______________________________________________________________________________

The purpose of this memorandum is to present the estimated cost impacts of the proposed 

requirements for pressure relief device (PRD) monitoring for the Polycarbonate (PC) Production, 

Acrylic and Modacrylic Fibers (AMF) Production, and Amino/Phenolic Resins (APR) 

Production source categories. The requirements for PC and AMF facilities are being proposed in 

40 CFR part 63, subpart YY, and the requirements for APR are being proposed in 40 CFR part 

63, subpart OOO. The requirements apply to major sources of hazardous air pollutants (HAP) 

emissions at existing and new facilities under the national emission standards for hazardous air 

pollutants (NESHAP). The addition of PRD monitoring to the NESHAP for these source 

categories is being proposed along with proposed changes evaluated under EPA’s Risk and 

Technology Review (RTR) program, which is addressing statutory requirements under section 

112(d)(6) and 112(f)(2) of the Clean Air Act (CAA). Section 1 provides background 

information, followed by the estimated costs of the impacts of the PRD monitoring program for 

each source category in section 2. 

1.0 BACKGROUND

Section 112 of the CAA establishes a comprehensive regulatory process to address 

emissions of HAP from stationary sources. In accordance with CAA section 112(c), the EPA 

identifies categories and subcategories of major sources that emit one or more of the HAP listed 

in CAA section 112(b). Section 112(d)(2) of the CAA then calls for the EPA to promulgate 

national technology-based emission standards for each listed category or subcategory of sources. 

For “major sources” that emit or have the potential to emit any single HAP at a rate of 10 tons or 

more per year or any combination of HAP at a rate of 25 tons or more per year, these 

technology-based standards must reflect the maximum reductions of HAP achievable (after 

considering cost, energy requirements, and non-air health and environmental impacts) and are 

commonly referred to as maximum achievable control technology (MACT) standards. 

Section 112(d)(6) then requires EPA to review the CAA section 112(d) technology-based 

standards and to revise them “as necessary, taking into account developments in practices, 

processes, and control technologies,” no less frequently than every 8 years. The residual risk 

review is described in section 112(f) of the CAA. Section 112(f)(2) of the CAA requires the EPA 

to promulgate standards for each category or subcategory of CAA section 112(d) sources “if 

promulgation of such standards is required in order to provide an ample margin of safety to 
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protect public health . . . or to prevent, taking into consideration costs, energy, safety, and other 

relevant factors, an adverse environmental effect.

In addition to the residual risk and technology reviews performed regarding the 

NESHAP, the EPA also reviews the existing provisions of the NESHAP during the RTR process. 

In 2008, the United States Court of Appeals for the District of Columbia Circuit vacated portions 

of two provisions in the EPA’s CAA section 112 regulations governing the emissions of HAP 

during periods of startup, shutdown and malfunction (SSM). Sierra Club v. EPA, 551 F.3d 1019 

(D.C. Cir. 2008), cert. denied, 130 S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the 

SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of a 

regulation, commonly referred to as the “General Provisions Rule,” that the EPA promulgated 

under section 112 of the CAA. When incorporated into CAA section 112(d) regulations for 

specific source categories, these two provisions exempt sources from the requirement to comply 

with the otherwise applicable CAA section 112(d) emission standard during periods of SSM. In 

light of and consistent with Sierra Club v. EPA, the EPA is proposing to eliminate the SSM 

exemption for all three source categories (AMF, PC, and APR) and require that they apply at all 

times, including during periods of SSM.

As part of the proposed elimination of the SSM exemption in these NESHAP, the EPA is 

proposing to require monitoring of PRDs in organic HAP service that release to the atmosphere 

and that a pressure release from such a PRD is a violation. The PRD monitoring system must be 

able to identify and record the time and duration of each pressure release and notify operators 

that a pressure release has occurred. Owners or operators would be required to report any 

pressure release and an estimate of the amount of organic HAP released to the atmosphere with 

the next periodic report. These provisions are being proposed due to concerns that PRD releases 

may emit large quantities of HAP, may not be identified and controlled in a timely manner and 

may be due to repeat problems that have not been corrected. The proposed provisions clarify that 

such release events would be violations of the emissions standards of these rules.

2.0 COST IMPACTS 

In order to estimate the costs associated with requiring monitoring of PRDs for AMF, PC, 

and APR production facilities, it was assumed that operators would install electronic indicators 

on each PRD in organic HAP service that vents to the atmosphere to identify and record the time 

and duration of each pressure release. However, owners or operators could use a range of 

methods to satisfy these requirements, including the use of a parameter monitoring system that 

may already have been in place on the process operating pressure that is sufficient to notify 

operators immediately that a pressure release is occurring, as well as recording the time and 

duration of that release. To estimate the cost of electronic indicators, analyses performed by the

South Coast Air Quality Management District (SCAQMD) of California were referred to, which 

requires continuous monitoring of a percentage of PRDs at refineries by installing a monitoring 

device capable of recording the duration of each release and quantifying emissions. Wireless 

technology allows continuous monitoring of PRDs and makes it easier for operators to identify 
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releases and leaks.1There are several monitoring devices that can be used, including acoustic 

sensors and pressure/differential pressure sensors. These sensor units communicate with a base 

radio that interfaces with the existing control system. The costs for PRD wireless monitoring are 

summarized in Table 1. These costs are based on an analysis documented by the SCAQMD for 

electronic monitoring devices for PRDs. 

The monitoring device cost provided by the SCAQMD was based on vendor costs and ranged 

from $5,000 to $10,000, with an average of $7,500, and includes device parts, installation, and 

maintenance, as well as a data retrieval system. According to SCAQMD, annual operating costs 

are minimal because they include periodic replacement of inexpensive batteries. It was assumed 

that, for this analysis, these costs were presented in 2007 dollars and were therefore escalated to 

2012 dollars. According to the SCAQMD document, the cost of electronic monitoring systems is 

not linear, and facilities requiring a larger number of monitors are expected to benefit from 

economies of scale. Therefore, the sixth-tenths rule was applied to calculate initial costs.

For PC, it was determined that of available model chemical manufacturing plants, the “simple” 

model plant would be most representative of the PC source category, which contains 2 PRDs. As 

a result, the total capital investment was determined to be $12,649 per facility and $1,801 

annually per facility. There are four facilities in the PC source category each assumed to have 

two PRDs. Therefore, the total capital cost associated with the requirement to monitor PRDs is 

$51,000 with an annualized cost of $7,000 for the PC source category.

For AMF, a single facility in the U.S. produces AMF and is subject to the AMF MACT 

standards: Cytec Carbon Fibers, LLC, in Greenville, SC. According to information provided by 

Cytec, there are 12 PRDs at the facility. Therefore, the total capital investment was estimated at 

$37,063 with an annualized cost of $5,277. Since there is only one facility in the AMF source 

category, the total capital cost and annualized cost for the source category are the same as the per 

facility cost. 

For APR, it was assumed that the “average” model plant would be most representative of the 

APR source category, which contains 5 PRDs. As such, the total capital investment estimated is 

$21,919 and $3,121 annually per APR facility. There are 18 facilities in the APR source category 

each with five PRDs. Therefore, the total capital cost associated with the requirement to monitor 

PRDs is $395,000 with an annualized cost of $56,000 for the APR source category.

 

1 Ellis, Kennard, SCAQMD. Final Staff Report for Proposed Amended Rule 1173 - Control of Volatile Organic 

Compound Leaks and Releases from Components at Petroleum Facilities and Chemical Plants. May 15, 2007. 

Docket No. EPA-HQ-OAR-2010-0869-0024.
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Table 1. Total Capital Investment and Annualized Cost of PRD Monitoring for the 

PC, AMF, and APR Source Categories

Cost Parameter PC AMF APR

Number of PRDs at Model Plant 2 12 5

Unit Device Installation Cost $7,500 (2007 Dollars)

$8,345 (2012 Dollars)a

Plant Site Total Capital Investmentb$12,649 $37,063 $21,919

Capital Recovery Factorc0.142b

Plant Site Total Annualized Cost $1,801 $5,277 $3,121

Number of Plants in Source Category 4 1 18

Source Category Total Capital Cost $51,000 $37,000 $395,000

Source Category Total Annualized Cost $7,000 $5,000 $56,000

a Chemical Engineering Index for 2007 is 525.4 and 584.6 for 2012.

b Calculated using sixth-tenths rule. Plant site Cost ($) = PRD Unit Cost ($) * (No. of PRDs)^0.6

c Capital recovery factor calculated based on 7 percent interest and 10 year equipment life.