PUBLICLY OWNED TREATMENT WORKS (POTWS) SCC: 2630020000 Publicly owned treatment works (POTW) facilities are owned by a municipality, state, an intermunicipality or interstate agency, and departments/agencies of the federal government. The definition of a POTW facility includes intercepting sewers, outfall sewers, sewage collection systems, pumping, power, and other equipment. The wastewater treated by these POTWs is generated by industrial, commercial, and domestic sources.1 The national emission estimates for POTW facilities were calculated using an interpolated nationwide flow rate for baseyear 2002, and then applying emission factors for VOCs, ammonia, and 53 HAPs. Nationwide projected flow rates for 2000 and 2005 were available from an EPA report2, and are summarized in Table 1. In 2000, flow rate was estimated to be 34,710 million gallons per day (MMGD); in 2005, flow rate was estimated to be 37,085 MMGD. The interpolated 2002 nationwide flow rate (using a linear regression) was calculated at 35,660 MMGD, or 13,015,900 million gallons annually. The ammonia emission factor was obtained from a report to EPA3, while the VOC emission factor was retrieved from FIRE program.4 Emission factors for the 53 HAPs were derived using 1996 area source emissions estimates that were provided by ESD5 and the 1996 nationwide flow rate.6 Table 2 lists the 53 HAPs, the 1996 area source emissions, and the derived emission factor in pounds per million gallons treated. It was assumed that the emission factors derived from the 1996 information are applicable for the year 2002. Emissions were allocated to the county- level by the county proportion of the U.S. population.7 Appendix B contains the total population data in database format. It is important to note that the emission estimates for this category represent total emissions. When the 2002 point source NEI is released, it will be necessary to determine whether there are point source emissions in SCCs 50100701 through 50100781 and 50100791 through 50182599 that will need to be subtracted to yield the nonpoint source emission estimates for this category. The national POTW flow rate estimate does not include Puerto Rico or the U.S. Virgin Islands. Emissions for Puerto Rico and the U.S. Virgin Islands were estimated using the approach outlined in the report text. Broward County in Florida is assumed to be the surrogate county for Puerto Rico. Monroe County in Florida is assumed to be the surrogate for the U.S. Virgin Islands. POTW emissions in the surrogate counties were divided by the population of the surrogate counties obtained from the U.S. Census Bureau to estimate emissions on a per capita basis.7 The per capita emissions were then multiplied by the population in each county of Puerto Rico and the U.S. Virgin Islands to estimate emissions. The emissions data reported in Table 2 include the emission estimates for Puerto Rico and the U.S. Virgin Islands. Example Calculations: The 1996 flow rate per day was 32,175 MMGD. (1996 was a leap year.) Annually, this computes to: 32,175 MMGD treated * 366 days = 11,776,050 million gallons treated Benzene emissions in 1996 for area source POTWs were estimated to be 461.44 tons peryear. The derived benzene emission factor is calculated as follows: Benzene emission factor = (461.44 tons * 2000 lb/ton)/(l 1,776,050 million gallons treated) Benzene emission factor = 0.078369 lb/million gallons treated Benzene estimates for 2002 for area source POTWs (exluding Puerto Rico and U.S. Virgin Islands) are calculated as follows: 2002 Benzene emissions = (35,660 MMGD * 365 days) * (0.078369 lb/million gallons treated) 2002 Benzene emissions = 1,020,043 pounds = 510.02 tons/year ------- PUBLICLY OWNED TREATMENT WORKS (POTWS) (continued) SCC: 2630020000 Data Parameters Table 1 - National Flow Rates, 1996-2005 Year Flow rate (MMGD) Reference 1996 32,175 6 2000 34,710 2 2002 35,660 interpolated by linear regression 2005 37,085 2 Table 2 - Emission Factors and National-Level Estimates Pollutant 1996 Emissions (tpy) Derived Emission Factor (lb/MMGAL) 2002 Emissions (tpy)1 1,1,2,2-Tetrachloroethane 0.12 2.0380E-05 0.1335 1,1,2-Trichloroethane 0.08 1.3587E-05 0.0890 1,2,4-Trichlorobenzene 5.92 1.0054E-03 6.5839 1,3-Butadiene 1.72 2.9212E-04 1.9129 1,4-Dichlorobenzene 14.76 2.5068E-03 16.4152 l-Chloro-2,3-Epoxypropane 0.31 5.2649E-05 0.3448 2,4-Dinitrotoluene 3.3 5.6046E-04 3.6701 2-Nitropropane 0.02 3.3967E-06 0.0222 Acetaldehyde 21.27 3.6124E-03 23.6552 Acetonitrile 23.67 4.0200E-03 26.3244 Acrolein 26.3 4.4667E-03 29.2493 Acrylonitrile 26.47 4.4956E-03 29.4384 Allyl Chloride 1.33 2.2588E-04 1.4791 Ammonia NA 1.90E+01 2 124,417.9275 Benzene 461.44 7.8369E-02 513.1862 Benzyl Chloride 0.56 9.5108E-05 0.6228 Biphenyl 5.16 8.7636E-04 5.7386 Carbon Disulfide 296.41 5.0341E-02 329.6496 Carbon Tetrachloride 77.35 1.3137E-02 86.0241 Chlorobenzene 33.13 5.6267E-03 36.8452 Chloroform 441.89 7.5049E-02 491.4438 Chloroprene 1.63 2.7683E-04 1.8128 Cresols (includes o,m,p) 0.11 1.8682E-05 0.1223 Dimethyl Sulfate 0.09 1.5285E-05 0.1001 Ethyl Acrylate 0.12 2.0380E-05 0.1335 Ethyl benzene 525.48 8.9246E-02 584.4077 Ethylene Oxide 15.22 2.5849E-03 16.9268 ------- Pollutant 1996 Emissions (tpy) Derived Emission Factor (lb/MMGAL) 2002 Emissions (tpy)1 Formaldehyde 1.35 2.2928E-04 1.5014 Glycol Ethers 788.86 1.3398E-01 877.3233 Hexachlorobutadiene 0.05 8.4918E-06 0.0556 Hexachlorocyclopentadiene 0.04 6.7935E-06 0.0445 Methanol 782.48 1.3289E-01 870.2278 Methyl Chloroform (1,1,1-Trichloroethane) 38.62 6.5591E-03 42.9509 Methyl Ethyl Ketone (2-Butanone) 195.16 3.3145E-02 217.0454 Methyl Isobutyl Ketone (Hexone) 184.45 3.1326E-02 205.1343 Methyl Methacrylate 21.31 3.6192E-03 23.6997 Methyl tert-Butyl Ether 4.37 7.4218E-04 4.8601 Methylene Chloride 625.92 1.0630E-01 696.1111 N,N-Dimethylaniline 22.10 3.7534E-03 24.5783 Naphthalene 90.00 1.5285E-02 100.0927 Nitrobenzene 0.45 7.6426E-05 0.5005 o-Toluidine 0.12 2.0380E-05 0.1335 P-Dioxane 1.23 2.0890E-04 1.3679 Propionaldehyde 0.24 4.0761E-05 0.2669 Propylene Dichloride 0.79 1.3417E-04 0.8786 Propylene Oxide 50.21 8.5275E-03 55.8406 Styrene 187.35 3.1819E-02 208.3596 Tetrachloroethylene 292.47 4.9672E-02 325.2678 Toluene 839.51 1.4258E-01 933.6532 Trichloroethylene 20.98 3.5632E-03 23.3327 Vinyl Acetate 5.25 8.9164E-04 5.8387 Vinyl Chloride 0.46 7.8125E-05 0.5116 Vinylidene Chloride 29.01 4.9269E-03 32.2632 VOC NA 9.90E+00 2 64,828.2886 Xylenes (includes o, m, and p) 4100.05 6.9634E-01 4,559.8322 1 Includes estimates for Puerto Rico and the U.S. Virgin Islands. 2 Actual emission factor, not derived. PUBLICLY OWNED TREATMENT WORKS (POTWS) (continued) SCC: 2630020000 References 1. U.S. Environmental Protection Agency. 64FR57572. National Emission Standards for Publicly Owned Treatment Works, Final Rule. 40 CFR Part 63. October 26, 1999. 2. U.S. Environmental Protection Agency. Biosolids Generation, Use, and Disposal in The United States. EPA530-R-99-009. September, 1999. Table A-8. 3. Battye, R. et al. "Development of Ammonia Emission Factors." EC/R. August, 1994. (Internet address: http ://207.158.206.57/docs/Batty e_Report.pdf) 4. U.S. Environmental Protection Agency. Factor Information Retrieval (FIRE) program. Version 6.23. ------- Memorandum from Bob Lucas, EPA to Greg Nizich, U.S. Environmental Protection Agency. "Review of Baseline Emissions Inventory." October 16, 1998. U.S. Environmental Protection Agency. "Facilities Database (Needs Survey) - Frequently Asked Questions." Internet address: www.epa.gov/oqm/faqwfd.htm. June 28, 2001. U.S. Census Bureau. 7/1/2002 County Population Estimates File and Components of Change, [Data file], April 17, 2003. Available from Population Estimates Branch Web site http://eire.census.gov/popest/estimates_dataset.php ------- |