MEMORANDUM 

TO: Bill Swietlik, EPA 

FROM: Deb Bartram, T.J. Finseth, Jill Lucy, Patrick Goodwin, ERG 

 

DATE: April 19, 2013 

SUBJECT: Comparison of Steam Electric Industry Toxic Loadings to Other Industrial 

Dischargers (SE02155) 

 The U.S. Environmental Protection Agency (EPA) is proposing revised effluent 

limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Point 

Source Category (40 CFR 423). In support of the development of the revised ELGs, ERG 

supported EPA in calculating pollutant loadings from steam electric power plants, as total 

pounds and as toxic-weighted pound equivalents (TWPEs). This memorandum provides a 

summary of the data and calculations performed to estimate the total loadings of toxic pollutants 

reported to be discharged to United States waters in industrial National Pollutant Discharge 

Elimination System (NPDES) permits, and the percentage of those toxic loadings that result from 

discharges by the steam electric industry. ERG calculated that the total pollutant loadings from 

steam electric power plants account for at least 50 to 60 percent of the toxic pollutants reported 

in industrial NPDES permits. This result is documented in EPA’s Environmental Assessment for 

the Proposed Effluent Limitations Guidelines and Standards for the Steam Electric Power 

Generating Point Source Category (EA Report) (DCN SE01995). 

 As part of the engineering support to EPA, ERG calculated pollutant loadings on a plantby-plant basis for all steam electric power plants that fell into scope of the proposed ELGs. The 

loadings methodology and calculations are documented in Section 10 of EPA’s Technical 

Development Document for the Proposed Effluent Limitations Guidelines and Standards for the 

Steam Electric Power Generating Point Source Category (TDD) (DCN SE01964). The total 

TWPE discharges from steam electric power plants are 5.2 million pounds per year excluding 

sulfides and 8.3 million pounds per year including sulfides. 

 To estimate the total TWPE from other industrial dischargers, ERG used data reported to 

EPA’s Discharge Monitoring Report (DMR) system for 2009. In support of its 304m annual 

review under Work Assignment 9-05, EPA compiled the DMR data into the 

DMRLoads2009_v02.mdb database (see DCN 07709, EPA-HQ-OW-2010-0824). ERG used the 

data tables in the DMR database and developed queries for the Steam Electric ELGs (see DCN 

SE01961), as follows: 

1. Use database table PSC/SIC Crosswalk to identify standard industrial category (SIC) 

codes that fall under point source category 40 CFR 423. The resulting SIC codes are 4911 

(electric services), 4931 (electric and other services combined), 4939 (combination 
Memorandum 

April 19, 2013 

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utilities), and 4961 (steam and air conditioning supply). For purposes of this analysis, 

these four SIC codes represent the steam electric industry. 

2. In a query (TWPE_minus_steam electric), select all TWPE results (lb-eq/yr) in database 

table DMR2009 for all parameters (i.e., pollutants) and all facilities that fall under any 

SIC code except those for the steam electric industry. See the database for the results. 

3. Building on the first query, sum the total TWPE (lb-eq/yr) for all parameters and 

facilities, except those identified as steam electric (query TWPE_minus_steam electric 

total). The total TWPE is 5.3 million pounds. 

Calculations 

Total TWPE from industrial sources reporting discharges under NPDES permits: 

Excluding Sulfides

5.2 million lb-eq/yr (steam electric) + 5.3 million lb-eq/yr (non-steam electric) = 10.5 million lb-eq/yr 

Including Sulfides

8.3 million lb-eq/yr (steam electric) + 5.3 million lb-eq/yr (non-steam electric) = 13.6 million lb-eq/yr 

Percentage of TWPE (i.e., toxic discharges) accounted for by steam electric plants: 

Excluding Sulfides

 5.2 million lb-eq/yr = 50 percent 

 10.5 million lb-eq/yr

Including Sulfides

 8.3 million lb-eq/yr = 61 percent 

 13.6 million lb-eq/yr