CITY OF PHILADELPHIA

Department of Public Health 

Environmental Protection Division 

Air Management Services 

InterOffice Memo 

To: File 

From: Maryjoy Ulatowski 

Date: 12/12/2014 

Subject: RACT Analysis for Southwest Pollution Control Plant (PLID # 09515) 

Company Description: 

Southwest Water Pollution Control Plant is a water treatment plant located at 8200 Enterprise Avenue, Philadelphia, 

PA 19153. The facility’s air emission sources include liquid treatment processes, solids treatment processes, four 

20-50 MMBTU/hr boilers, five boilers <10 MMBTU/hr, four digester gas flares , a steam cleaner and 10 cold 

degreasers. 

Applicability for NOx and VOC RACT: 

Southwest Pollution Control Plant (PWPCP) is not a major source for Nitrogen Oxides (NOx) emission having 

potential NOx emissions less than 100 tons per year, the major source threshold in Philadelphia County that is 

applicable to NOx RACT for the 1997 8-hour ozone NAAQS. 

The facility is not a major source of Volatile Organic Compounds (VOC) having potential VOC emissions is greater 

than 50 tons per year, the major source threshold in Philadelphia County that is applicable to VOC RACT for the 

1997 8-hour ozone NAAQS. 

The facility is being re-evaluated for RACT under the 1997 8-hour Ozone National Ambient Air Quality Standards 

(NAAQS). 

NOx Emission Sources and NOx RACT Analysis: 

Process Descriptions – NOx Sources:

SWPCP NOx emission sources include combustion sources such as boilers, flares, and cogeneration facility. 

Below is a list of NOx sources at the NWPCP and the potential to emit (PTE). 

The combined NOx were calculated based AP-42 factors. The combined NOx potential emission is less than 61 tpy. 

Therefore the facility is not applicable to NOx RACT requirements. 

Following is the PTE calculation based on AP-42 factors using the worst-case scenario for NOx: 

Boilers 

Title V Permit 

ID No. Source Description Capacity btu/hr Fuel Type 

NOX Tons 

per year 

CU-001 Cleaverbrooks Boiler 5,320,000 #2 Oil, Digester Gas 3.329

CU-002 Cleaverbrooks Boiler 5,320,000 #2 Oil, Digester Gas 3.329

CU-003 Burnham Boiler 26,780,000 #2 Oil, Digester Gas 16.757

CU-004 Burnham Boiler 26,780,000 #2 Oil, Digester Gas 16.757

CU-005 Burnham Boiler 26,780,000 #2 Oil, Digester Gas 16.757

CU-006 Burnham Boiler 26,780,000 #2 Oil, Digester Gas 16.757

CU-007 Weather Right Boiler 5,320,000 #2 Oil, Digester Gas 3.329

CU-014 HB Smith Boiler 4,853,000 #2 Oil, Digester Gas 3.037

CU-015 HB Smith Boiler 4,853,000 #2 Oil, Digester Gas 3.037
Flares 

Title V 

Permit ID 

No. Source Description 

Capacity 

SCF/hr Fuel Type 

NOX Tons 

per year 

CU-010 SW Digester Gas Flare 51,300 #Digester Gas 0.08

CU-011 SW Digester Gas Flare 51,300 #2 Oil, Digester Gas 0.08

CU-012 SW Digester Gas Flare 51,300 #2 Oil, Digester Gas 0.08

CU-013 SW Digester Gas Flare 51,300 #2 Oil, Digester Gas 0.08

Steamer 

Title V 

Permit ID 

No. Source Description 

Capacity 

btu/hr Fuel Type 

NOX Tons 

per year 

MISC003 

08 Steam Cleaner 600,000 Natural Gas 0.26

 Total NOx PTE 60.2 tpy 

 

VOC RACT Analysis: 

SWPCP VOC emission sources include combustion sources and wastewater treatment plant operations. Below a list 

of VOC sources at the SWPCP and the potential to emit (PTE) calculation for the facility. 

Combustion Sources:

Heating Capacity(Btu/hr) 

*Natural Gas 

Input (SCF/hr) 

VOC Factora

 

(lbs NOx/106 SCF) 

Operating hours per 

year 

Voc 

Tons per 

year 

5,320,000 5216 5.5 8760 0.13 

5,320,000 5216 5.5 8760 0.13 

26,780,000 26255 5.5 8760 0.63 

26,780,000 26255 5.5 8760 0.63 

26,780,000 26255 5.5 8760 0.63 

26,780,000 26255 5.5 8760 0.63 

5,320,000 5216 5.5 8760 0.13 

4,853,000 4758 5.5 8760 0.11 

4,853,000 4758 5.5 8760 0.11 

600,000 588 5.5 8760 0.01 

3.150 

*Assuming the heating value of natural gas is 1020 Btu/scf 

 
Flares:

Heating capacity(106 

Btu/hr) 

*Natural Gas 

Input (SCF/hr) 

VOC Factor -

AP42 Table 

13.5-2 (lbs 

VOC/106 Btu) 

Operating 

hours per year 

VOC Tons per 

year 

47 45860 0.55 8760 0.01 

47 45860 0.55 8760 0.01 

47 45860 0.55 8760 0.01 

47 45860 0.55 8760 0.01 

0.051 

Wastewater treatment plant operations including pretreatment, 

The potential to emit for VOC at the SWPCP for wastewater treatment operations is estimated to be 10.5 tons per 

year. This number was obtained by looking at facility’s monthly VOC estimates for the last three years (July 2011- 

June 2014) and the highest monthly estimate was used and multiplied by 12, for a yearly PTE number. These 

estimates were developed using the TOXCHEM model that was tailored for wastewater facilities. The TOXCHEM 

model is an EPA-approved proprietary software package developed and distributed by Enviromega, Ltd. The model 

essentially is a sophisticated mass balance that incorporated kinetic equations to determine the fate of organic 

compound. Influent VOC concentrations and plant flows were used in the model to estimate the monthly 

concentration of VOC. 

 

MONTH 

2014 lbs Carbon 

/month

2013

lbs Carbon 

/month

2012

lbs Carbon 

/month

2011 

 lbs Carbon 

/month

JAN 1219 1,301 1,025 

FEB 1536 1,085 1,014 

MAR 1559 1,331 1,066 

APR 1528 1,009 1,453 

MAY 1656 864 1,192 

JUN 1743 1,059 1,092 

JUL 1,118 1,176 1163 

AUG 1,366 1,381 1433 

SEP 1,108 1,068 1367 

OCT 947 985 1291 

NOV 911 864 928 

DEC 999 937 1215 

 
PTE VOC = (1743/2000) *12 = 10.5 tpy 

10 Cold Degreasers VOC PTE (tpy)

Following is the PTE VOC calculation for the degreaser is based on using AP-42 factor, 3.3

Section, Table 4.6-2: 

VOC PTE = AP-42 emission factor x (number of unit) 

VOC PTE = (0.33 tons/year/unit) X 10 unit 

VOC PTE = 3.3 tons/year 

Cold-cleaning degreasing operations at the facility shall complying with the RACT requirements of 25 PA Code 

129.63 

The total VOC PTE for the facility is less than 17 tpy. 

Conclusions and Recommendations: 

Since the potential for VOC and NOx sources are below the applicable RACT limits, the facility is not applicable to 

RACT under he 1997 8-hour ozone standard.. 

1/9/15

Edward Wiener, Chief of Source Registration Date