MEMORANDUM

TO: William Swietlik, EPA

FROM: Jessica Wolford, ERG Elizabeth Sabol, ERG

DATE: 24 November 2010

SUBJECT: Methodology for Analyzing Landfill Iron Concentrations in the 2008 DMR Loadings Tool

1.0 I NTRODUCTION

As part of the 2010 annual review of the Landfills Category, ERG reviewed iron discharges in the 2008 DMR database, because they ranked high, in terms of TWPE. As directed by EPA, ERG analyzed data to answer the following questions:

 Are the iron discharges in the database accurate;

 If so, are the iron discharge concentrati ons above treatable levels; and finally

 Could landfills with high iron discharges treat their wastewater and remove iron

to lower concentrations?

EPA is requesting this information to support their determination of whether iron discharges from landfills are sufficiently regulated by existing effluent limitations guidelines. Part 445, the Landfills Pont Source Category do es not currently set limits for iron. The Development Document for Final Effluent Limitations Guidelines and Standards for the Landfills Point Source Category (Landfills Development Docume nt) (January 2000) indicates that “EPA excluded pollutants th at are naturally occurring com pounds in soil or ground water at landfill facilities or pollutants that are used as treatment chemicals in this industry...” This included iron, along with other pollutants (U.S. EPA, 2000).

2.0 M ETHODOLOGY

ERG compared the 2008 iron concentrations from landfills discharges to EPA’s Method 200.7 iron method detection limit (MDL) and treatab le iron concentrations. ERG extracted the

2008 iron concentrations in landf ill discharges from EPA’s DMR Loadings Tool. ERG then compared these values to the iron MDL and treatable levels.

ERG compared the 2008 iron concentrations to treatability concen trations achievable by chemical precipitation and biologi cal treatment because they were the best available technology (BAT) basis used to set limits for Subpart A: RCRA Subtitle C Hazardous Waste Landfills (40 CFR Part 445 Subpart A) 1 . No iron treatability data were available in the Landfills Development

1 The BAT basis used to set limits for Subpart B: RCRA Subtitle D Non-Hazardous Waste Landfills (40 CFR Part 445 Subpart B) is reverse osmosis. ERG did not have meta ls removal data for reverse osmosis, but facilities withMemorandum November 24, 2010 Page 2

Document; therefore, ERG used treatability da ta for chemical precip itation and biological treatment already collected during previous annual reviews 2 (U.S. EPA, 2009). ERG used treatment data collected from four plants refe renced in the Steam Elect ric Detailed Study (U.S. EPA, 2009) and reviewed data from two lit erature sources that included treatability

concentrations from 64 sites. Because the data found in the literature so urces were incomplete and provided conflicting ranges of iron concentr ations, ERG only analyzed the concentrations reported in the Steam Electric Deta iled Study Report. The pH of th e wastewater from coal-fired power plants, typically ranging from 4.5 to 7.0 S.U., is similar, al though more neutral, to landfill wastewater, typically 3.7 to 8.0 S.U. (U.S. EPA, 2009).

ERG used EPA’s Method 200.7 MDL for iron because of the conve ntional laboratory techniques and instrumentation used and its ability to measur e trace concentrations. Table 1 presents EPA’s Method 200.7 MDL for iron and th e concentrations achievable by chemical precipitation and biolog ical treatment.

Table 1. MDL and Treatable Iron Concentrations

EPA 200.7 MDL (mg/L) Chemical Precipitation Treatment Concentration Range (mg/L) Biological Treatment Concentration Range (mg/L)

0.03 0.019 – 6 ND (0.0022) – 23

Source: Method 200.7 Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry (U .S. EPA, 1994); and 2009 Steam Elec tric Power Generating Point Source Category: Final Detailed Study Report (U.S. EPA, 2009).

MDL – Method detection limit. ND –Non-detect. Detection limit indicated in ( ).

The DMR Loadings Tool contains pollutant concentrations for each facility, outfall, and monitoring period. Facilities report up to th ree concentrations (m inimum, average, and maximum) for each facility, outfall, and monitoring period combination. 3 The DMR Loadings Tool also flags concentrations that are repor ted as below the detection limit (BDL). ERG developed the following procedure to accurately re present and review the iron concentrations for facilities in the Landfills Category:

1. ERG extracted the iron concentrations for landfills from the 2008 DMR Loadings Tool. There were a total of 3,404 iron con centrations in the 2008 DMR Loadings

Tool for landfills.

2. ERG excluded iron concentrations reported as BDL for all monitoring periods for a given outfall by excluding outfalls w ith zero iron load. ERG excluded these concentrations from the analysis beca use, by definition, concentrations below

reverse osmosis treatment should be able to achieve polluta nt removal at least as well as chemical precipitation and biological treatment.

2 As part of the Steam Electric Powe r Generating Point Source Category Detailed Study, EPA collected treatability data for chemical precipitation and biological treatment sy stems. Iron was included in the treatability data (U.S. EPA, 2009).

3 In the DMRLoads2008_v02 screening level database, EPA has estimat ed loads for facilities based on a single concentration, selected by prioritizing the average concen tration first, then the maximum and finally the minimum, when computing pollutant loads for specific facility.Memorandum November 24, 2010 Page 3

detection are below treatabl e levels. This excluded 2,113 concentrations, leaving a total of 1,291 4 iron concentrations in the analysis.

3. ERG removed 0 mg/L concentrations as EPA assumes these reported results infer

concentrations below detectable levels. This excluded another 5 concentrations from the analysis leaving a total of 1,286 ir on concentrations that were reported as detected above 0 mg/L.

4. ERG removed concentrations that were re ported BDL as these concentrations are

below treatable levels. This exclude d 21 concentrations, leaving 1,265 iron concentrations in the analysis.

5. Because facilities can report multiple c oncentrations for each monitoring period (i.e., minimum, average, and maximum) , ERG used the following hierarchy to

select one concentration for each facili ty, outfall, and monitoring period, referred

to as the “final” iron concentrations:

a. Selected the average concentration (c onsidered the most representative);

and

b. If the average concentration was not reported, selected the maximum

concentration. Note: The DMR Loadings Tool does not include any minimum iron concentrations for landfills, likely because landfills are not required to report

minimum concentrations.

6. ERG compared the final iron concentrations reported above the detection limit for one or more monitoring periods to the EPA Method 200.7 MDL for iron to

determine if the iron concentrations were at detectable levels. ERG determined that 37 iron concentrations (approximat ely 3 percent), were below the MDL reported in EPA Method 200.7. ERG removed these 37 concentrations from the analysis, leaving a total of 1,228 iron concentrations.

7. ERG calculated the median, average, and maximum of the remaining 1,228 iron

concentrations above the detection limit and the EPA Method 200.7 MDL.

8. ERG used the median concentration for the remaining analyses. ERG chose the median instead of the mean concentration for accuracy. 5

Table 2 shows the statistical values for the iron concentrations.

Table 2. MDL and Treatable Iron Concentrations

Range of Iron Concentrations Reported (Minimum-Maximum mg/L) Median Concentration (mg/L) Mean Concentration (mg/L)

0.032-33,000 0.929 43.29

4 Note that some of 1,291 these iron concentrations could still have BDL indicators. In step 2, iron concentrations were only removed if all monitoring period c oncentrations for a given outfall were BDL.

5 The DMR Loading Tool often contains data that were ente red erroneously, such as with units of mg/L instead of ng/L. Erroneous data could skew the average iron concentration. Additiona lly, EPA excluded two facilities, BFI Backridge Sanitary Landfill, in La Grange, MO and High Plains Sanitary Landfill, in Floweree, MT, because the reported concentrations were unreasonably high (over 1,000 mg/L and 300 mg/L, respectively), and ERG suspects data entry errors.Memorandum November 24, 2010 Page 4

ERG completed the analysis by comparing the median iron concentration to the treatable concentration ranges shown in Table 1. ERG determ ined that the median iron concentration for all outfalls is less than the biological treatment or chemical treatability concentrations. As shown in Figure 1, approximately 89 percent of the iron concentrations are below the chemical precipitation treatability (below 6 mg/L) a nd 98 percent are below biological treatment treatability (below 23 mg/L). The remaining iron concentrations above the chemical precipitation treatment range are reported by a total of 24 facilities, seven of which are also above the biological treatment range. ERG pr edicts that database entry e rrors contribute to the high iron concentrations (i.e., 85 mg/L) shown in Figure 1. For further information on the analysis, see Section 8.5 of the 2010 TSD (EPA, 2010).01020304050607080900.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0Percent of Concentrations Equal to or Less than the Treatability Value

Iron Concentration (mg/L)Iron ConcentrationChem. Precp. Treatability ConcentrationBiological Treatability ConcentrationFigure 1. Landfills Iron Concentration Probability Plot3.0 R EFERENCES

1. U.S. EPA. 2000. Development Document for Final Effluent Limitations Guidelines and Standards for the Landfills Point Source Category . EPA-821-R-99-019. Washington, DC. (January). Available online at: http: //www.epa.gov/waterscience/guide/landfills/

final/index.html.

2. U.S. EPA. 2009. Steam Electric Power Generating Point Source Category: Final Detailed Study Report . EPA-821-R-008. Washington, DC . (October). EPA-HQ-OW2008-0517-0413

3. U.S. EPA. 2010. Technical Support Document for the 2010 Effluent Guidelines Program

Plan . EPA-HQ-OW-2008-0517.Washington, DC (December). DCN 07320.