                      ALLEGHENY COUNTY HEALTH DEPARTMENT
                              AIR QUALITY PROGRAM
                                       
                               November 29, 2021
                                       
SUBJECT:	Reasonable Available Control Technology (RACT II) Determination
            GenOn Cheswick Generating Station
            Pittsburgh & Porter Street
            Springdale, PA 15144
            Allegheny County

            Title V Installation Permit No. 0054-I005a
 		
TO:		JoAnn Truchan, P.E.
            Section Chief, Engineering

FROM:		Bernadette Lipari
      Air Quality Engineer

 Executive Summary

The Cheswick Generating Station (Cheswick) is defined as a major source of NOX and VOC emissions and was subjected to a Reasonable Available Control Technology II (RACT II) review by the Allegheny County Health Department (ACHD) required for the 1997 and 2008 Ozone National Ambient Air Quality Standard (NAAQS). The findings of the review established that technically and financially feasible RACT would result in the following emissions changes, summarized below.


 Regulatory Basis

ACHD requested all major sources of NOX (potential emissions of 100 tons per year or greater) and all major sources of VOC (potential emissions of 50 tons per year or greater) to reevaluate NOX and/or VOC RACT for incorporation into Allegheny County's portion of the PA SIP. 

A case-by-case RACT II permit was issued on February 28, 2020 (#0054-I005), which included emissions averaging of the Main Boiler No. 1 with the Brunot Island Generating Station. On August 27, 2020, the U.S. Third Circuit Court of Appeals issued an opinion in Sierra Club v. EPA, 3d. Cir. No. 19-2562 vacating and remanding three aspects of the U.S. Environmental Protection Agency's (EPA) May 19, 2019 approval of DEP's 2016 reasonably available control technology (RACT II) Rule to reduce ozone pollution from coal-fired power plants. Sierra Club challenged EPA's approval of the RACT II Rule's NOX emission limit for coal-fired power plants with selective catalytic reduction (SCR) pollution controls; the inlet operating temperature threshold for power plants to operate SCR pollution controls; and operating temperature data recordkeeping and reporting requirements. The Court found EPA's approval of these three provisions of the RACT II Rule to be arbitrary and capricious, because they were not supported by the administrative record. As a result, the Court vacated EPA's approval of these three provisions and remanded them back to the agency for further action. As a result of this action, GenOn Cheswick was required to submit a new case-by-case RACT analysis for the Main Boiler No. 1.  This amendment includes eliminating the averaging plan with the Brunot Island Generating Station (#0056) and removing the alternate limit for operation of the SCR at <600 °F.


 Facility Description, Existing RACT I and Sources of NOX

The Cheswick Generating Station is an electric generating facility located on Pittsburgh and Porter Streets in Springdale, PA. The plant is composed of one main boiler exhausting to one stack, which fires coal (including synfuel) as the primary fuel and natural gas as an auxiliary fuel for startup, shutdown, and during upset conditions. Pollution control equipment for the main boiler includes low NOX burners, electrostatic precipitation with flue gas conditioning, selective catalytic reduction, and flue gas desulfurization (FGD). The plant also has a No. 2 oil-fired auxiliary boiler which exhausts to a separate stack. Cheswick is a major source of NOX and VOC emissions.
   
On March 8[th], 1996 the facility entered into a consent decree with the Department to meet RACT I obligations under RACT Order No. 217. RACT Order 217 was approved as RACT by EPA in 2001 (66 FR 52867). The RACT I requirements are to operate the Main Boiler No. 1 with properly maintained and operated low NOX concentric firing system II and a NOX CEMS. The NOX emissions were limited to 0.5548 lb NOX/MMBtu (24 hours), 0.45 lb NOX/MMBtu (annually), and 10,840 tons NOX/yr. All processes and controls are to be operated and maintained according to good engineering practice. Additional requirements are to maintain records of production and fuel usage demonstrating compliance.

Table 1
Facility Sources Subject to Case-by-Case RACT II and Their Existing RACT I Limits
Source ID
Description
Rating
NOX PTE (TPY)
                         Proposed Case-by-Case RACT II
S-001
Main Boiler No. 1: Tangentially-Fired Coal Boiler
5,500 MMBtu/hr (maximum continuous rating)
10,840
                                 6.48 tons/day
                                  Daily Limit
     CEMS 24-hour block total, based on a maximum 0.090 lb/MMBtu with SCR 
25 Pa Code
§129.99(b)




                                0.27 lb/MMBtu 
 CEMS 24-hour block total, based on a maximum 0.27 lb/MMBtu with SCR under all operating conditions
25 Pa Code
§129.99(b)




                                   540 lb/hr
                                  30-day Limit
CEMS rolling average emissions rate averaged over 30 valid boiler operating days. (includes all operating scenarios and all valid reporting hours)
25 Pa Code
§129.99(b)




                                 2,365 ton/yr
                Maximum annual emissions based on 30-day limit
25 Pa Code
§129.99(b)
Source ID
Description
Rating
VOC PTE (TPY)
                         Proposed Case-by-Case RACT II
S-001
Main Boiler No. 1: Tangentially-Fired Coal Boiler
5,500 MMBtu/hr (maximum continuous rating)
                                     82.0
                                     82.0
The permittee shall install, maintain and operate the source in accordance with the manufacturer's specifications and with good operating practices.
25 Pa Code
§129.99(b)

Table 2
Facility Sources Subject to the Presumptive RACT II per PA Code 129.97 
                                   Source ID
                                  Description
                                    Rating
                                 NOX PTE (TPY)
                                 VOC PTE (TPY)
                             Basis for Presumptive
           Presumptive RACT Requirement (25 Pa Code Section 129.97)
S-002
Auxiliary Boiler: No. 2 fuel oil-fired
160 MMBtu/hr
                                      8.4
                                     0.13
                               > 50 MMBtu/hr
129.97(g)(ii); 0.12 lb/MMBtu/hr NOx on a 30-day rolling average, and 8.4 tons/yr.

Diesel Air Compressor
465 HP
                                     1.61
                                     0.02
                                 < 5 TPY NOX
129.97(c)(1); The permittee shall install, maintain and operate the source in accordance with the manufacturer's specifications and with good operating practices.

Diesel Air Compressor
465 HP
                                     1.61
                                     0.02
                                < 5 TPY NOX
129.97(c)(1);The permittee shall install, maintain and operate the source in accordance with the manufacturer's specifications and with good operating practices.




Table 3
Facility Sources Exempt from RACT II per PA Code 129.96(c) {< 1 TPY NOX}
                                   Source ID
                                  Description
                                    Rating
                                 NOX PTE (TPY)
                                 VOC PTE (TPY)
B001
Space Heaters (7 units)
0.6 x 4, 0.35 x 2, 0.15 x 1 [MMBtu/hr x Quantity]
                           < 0.25 (largest unit)
                                    <0.1

 RACT Determination

The RACT permit application #0054-I005a, dated April 1, 2021, has a complete RACT analysis.  Based on the technical and economic infeasibility of different control technologies and SCR operational scenarios, RACT is the current use of SCR and compliance with the proposed optimized NOX emissions limitations listed in Table 1 above. Compliance with the emissions limits will be demonstrated using CEMS, which will measure NOX emissions. The Facility currently controls ammonia injection at optimal set points. 

In addition to the Facility's analysis, ACHD and the PA DEP performed a technical evaluation to address RACT requirements for the main power generating coal-fired combustion unit at the Cheswick Generating Station.   The DEP analysis is in Appendix A.  The Facility is proposing to limit NOX emissions to a maximum of 6.48 tons/day on a 24-hour block average with SCR, and a maximum of 0.27 lb/MMBtu on a 24-hour block average with SCR under all operating conditions, and 540 lb/hr, on a 30-day rolling average basis at all operating loads (i.e., normal load, low load, and startup and shutdown). 

The Department has determined that the VOC RACT, for the Main Boiler No. 1, is continued compliance with existing requirements. The existing permit effectively limits the VOC emissions to less than 0.0034 lb/MMBtu, annually. To put the selected RACT limits into a broader context, the Department reviewed the EPA's RBLC (i.e., Code: 11.220 Utility and Large Industrial Size Boilers/Furnaces >250 MMBtu/hr Coal) over the last 10 years. The VOC limits are comparable with the VOC limits identified in the RBLC search.

 RACT Emissions Summary
  
The conditions of Plan Approval Order and Agreement No. 217, issued March 8[th], 1996, as well as the limits in RACT IP #0054-I005, have been superseded by the case-by-case and presumptive RACT II conditions in this proposed permit amendment.  The RACT II conditions are at least as stringent as those from RACT I. Based on the findings in this RACT analysis, the Cheswick facility emissions can be summarized as follows:

Table 4
RACT II NOX Emissions Reduction Summary

                         NOX Potential Emissions (tpy)
                             PTE Prior to RACT II
                                RACT Reduction
                                  Revised PTE
                                    10,883
                                     8,506
                                     2,377


Table 5
RACT II VOC Emissions Reduction Summary

                         VOC Potential Emissions (tpy)
                             PTE Prior to RACT II
                                RACT Reduction
                                  Revised PTE
                                     82.1
                                       0
                                     82.1


The Installation Permit amendment is being modified to include the RACT II recommendations made by the PA DEP included in Appendix A. The following permit conditions have been modified or added:

 Conditions V.A.1.b.1) through 4);
 Condition V.A.1.d;
 Conditions V.A.3.a.1) and 2); and
 Condition V.A.6.e through Condition V.A.6.k.

 RACT II Permit Conditions




                                   Source ID
                                  Description
                          Permit 0054-I005 Condition
                                  Regulations
                                       
                                       
                                       
                               Main Boiler No. 1
                               Condition V.A.1.b
                               Condition V.A.1.c
                               Condition V.A.1.d
                                Condition V.A.2
                               Condition V.A.3.a
                               Condition V.A.3.b
                               Condition V.A.3.c
                               Condition V.A.4.a
                               Condition V.A.4.b
                               Condition V.A.4.c
                               Condition V.A.4.d
                               Condition V.A.4.e
                               Condition V.A.4.f
                               Condition V.A.4.g
                               Condition V.A.4.h
                               Condition V.A.4.i
                               Condition V.A.4.j
                               Condition V.A.5.a
                               Condition V.A.5.b
                               Condition V.A.5.c
                               Condition V.A.5.d
                               Condition V.A.6.a
                               Condition V.A.6.b
                               Condition V.A.6.c
                               Condition V.A.6.d
                               Condition V.A.6.h
                               Condition V.A.6.i
                               Condition V.A.6.j
                              25 PA Code §129.99
                              25 PA Code §129.99
                              25 PA Code §129.99
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                              25 PA Code §129.99
                              25 PA Code §129.99
                             25 PA Code §129.100
                             25 PA Code §129.100
                              25 PA Code §129.99
                              25 PA Code §129.99
                              25 PA Code §129.99
                                       
                                       

                                       
                               Auxiliary Boiler
                                       
                               Condition V.B.1.b
                               Condition V.B.1.c
                               Condition V.B.1.d
                               Condition V.B.1.e
                               Condition V.B.2.a
                               Condition V.B.2.b
                                Condition V.B.3
                               Condition V.B.4.a
                               Condition V.B.4.b
                               Condition V.B.4.c
                               Condition V.B.4.d
                               Condition V.B.5.a
                               Condition V.B.5.b
                               Condition V.B.6.a
                               Condition V.B.6.b
                              25 PA Code §129.99
                    25 PA Code §129.97(g)(1)(ii), §129.99
                             25 PA Code §129.100
                    25 PA Code §129.97(g)(1)(ii), §129.99
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                             25 PA Code §129.100
                              25 PA Code §129.99
                              25 PA Code §129.99
       















                                  APPENDIX A
