MEMORANDUM

From: William Swietlik, USEPA/OW/OST Ph: (202) 566-1129, Swietlik.william@epa.gov

To: Public Docket for the Preliminary 2016 Effluent Guidelines Program Plan EPA Docket Number EPA-HQ-OW-2015-0665 ( http://www.regulations.gov )

Date: February 16, 2016

Re: Summary of Methodology for Hand ling Non-Detect Data: 304m and S team Electric Power Generating

As part of its 2015 Annual Review of effluent limitations guide lines and standards (ELGs), EPA performed a toxicity ranking analysis (TRA) of all industrial categories, including those subject to existing ELGs and those not currently regulate d by ELGs, consistent with the methodology described in Section 2 of the 2015 Annual Effluent Guidelines Review Report (2015 Annual Review Report) (U. S. EPA, 2016). For its annual re views, EPA relies on discharge monitoring report (DMR) data re ported to the Integrated Complia nce Information System for the National Pollutant Discharge El imination System (ICIS-NPDES) an d Toxics Release Inventory (TRI) data downloaded from the DMR Pollutant Loading Tool 1 . While these data sets represent the best available existing data EPA has to evaluate pollutants in industrial wastewater discharge,

the data are derived differe ntly and in many cases, provide lim ited qualifying information regarding reported non-detect va lues. Recognizing the limitatio ns of the data sets, EPA established an approach for hand ling non-detect data for the pu rpose of its 304m annual reviews, as initially outlined in the 2009 Technical Support Document for th e Annual Review of Existing Effluent Guidelines and Identification of Potential New Point Source Categories (2009 Screening Level Analysis or “ SLA” Report) (U.S. EPA, 2009).

This memorandum summarizes EPA’s established methodology for ha ndling non-detect data for the purpose of its 304m annual reviews and compares th at methodology to the methodology EPA used in the Final R ule for the Steam Electric P ower Generating Effluent Guidelines (80 FR 67838). EPA ac knowledges that in certain aspe cts the 304m methodology for handling non-detect data may be different than the methodology employed for ELG rulemakings; most recently for the Steam Elect ric Power Generating ELG, whic h is appropriate given the data

and information available and the purposes of the analyses. Fur thermore, in the rulemaking context, for non-detect data , EPA often has access to qualifyin g information from the laboratory it can use to more accurately characterize non-detect discharge s.

1 See http://cfpub.epa.gov/dmr/.Memorandum February 16, 2016 Page 2

1.1 Terminology

For the purpose of this memorandum, EPA references the followin g terms (as defined for the Steam Electric Power Generating rulemaking):

 Method Detection Limit (MDL): The minimum concentration of a substance that can be measured and reported with 99 percen t confidence that the analy te concentration is greater than zero.

 Quantitation Limit (QL): The minimum concentration of a substance that can be reported with a specified degree of confidence that the analyte concentration is less than that minimum concentration and g reater than the MDL. The QL can be no lower than the

concentration of the lowest init ial calibration standard. The Q L is often referred to in ELG support documents as the reporting limit.

 U-Qualified Result or Non-Detect: The observation below the MDL, often reported as “U” by the analytical laboratory. E PA generally refers to this value as a non-detect.

 J-Qualified Result: Observations reported with an e stimated value and associated “ J” flag by the analytical laborator y, indicating a definitive obse rvation of the analyte in the sample that is measured above the MDL but below the lowest init ial calibration point.

1.2 Non-Detect Methodology

1.2.1 304m Non-Detect Methodology for DMR data

For 304m, EPA uses DMR data (e .g., concentrations, quantities, flows) reported in ICISNPDES to calculate annua l pollutant loadings.

NPDES dischargers report a valu e and, if appropriate, a qualifi er (e.g., =, <, >) for each monitoring period (for each po llutant and outfall) to their EPA or state permit program. EPA or state permit programs review the DMRs and upload the raw data i nto ICIS-NPDES. As stated in the DMR Pollutant Loading Tool FAQs, 2 ICIS-NPDES allows EPA and state permit programs to identify pollutant concentrations that are below detection (e.g ., commonly the QL, but could also be the MDL) by using a “less than” qualifier (<). However, ICIS -NPDES only allows EPA and states to identify a single valu e and qualifier when pollutant monitoring data are below detection, eliminating the ability to report all pertinent laboratory info rmation (e.g., MDL , QL, J-value). The following is a common data ent ry procedure used to accommod ate the system requirement to only report one value and one qua lifier for monitoring data that are below detection; however,

there are no standards or guidance for reporting:

 “0” (the number zero) in the valu e field and the “=” qualifier when the pollutant

concentration is below the MDL.

2 See http://cfpub.epa.gov/dmr/faq.cfm.Memorandum February 16, 2016 Page 3

 The QL in the value field and the “<” qualifier when the pollut ant concentration is below the QL.

The DMR Pollutant Loading Tool e mploys one of two options in ca lculating annual pollutant loadings that include r esults identified as below det ection (which could be reported as the QL or MDL). All other report ed values with qualifiers (e.g. , =, >) are treated as the specific value reported.

 If all monitoring period concentrations or quantities reported for the calendar year have a less than qualifie r (<), the total annual load is set to zero.

 If at least one monitoring peri od concentration or quantity rep orted during the year does not have a “<” qualifier (i.e., th e pollutant is detected at le ast once), the total calculated annual load is estimated using one half of the reported value f or qualified concentrations or quantities and the reported va lues for detected results.

This methodology is consistent w ith the established 304m annual review methodology as described in the 2009 SLA Report (U.S. EPA, 2009).

Analytical methods used for DMR d ata are specified in a facilit y’s NPDES permit. The standard conditions of the permit require that, when available, permittees use test procedures specified in 40 CFR Part 136. EPA a lso allows NPDES regulated f acilities to use alternate analytical wastewater methods. 3 However, information about the laboratory analytical methods i s not collected on DMRs, which mean s that EPA cannot identify the laboratory analytical methods used by NPDES dischargers in the raw data.

1.2.2 304m Non-Detect Methodology for TRI data

For TRI data, the facilities re port estimated annual loadings a ssociated with releases to surface waters and POTWs. These annual loadings can be based on engineering estimates or specific monitoring data. Unlike DMR, EPA does not calculate an nual loadings for TRI data based on concentration, quantity, or f low data for a reporting period, as these data are not

available in the raw TRI dataset.

If a facility uses monitoring data to estimate annual loadings for TRI, TRI guidance suggests facilities use one half the detection limit to estimat e annual loadings associated with non-detect results, except for cer tain pollutants. For example, current TRI guidance for dioxin suggests using a value of zero f or non-detect results instead o f one half the detection limit, if that is how the method being used treat s non-detects (e.g., EPA Meth od 1613). Because the facilities report the estimated releases di rectly to TRI, the details abou t the underlying estimation method and monitoring data are unknown (e.g., analytical method, QL, M DL). EPA notes that the use of

one half the detection limit is not applied consistently to TRI data (as it is up to the facility

3 See http://www.epa.gov/cwa-met hods/alternate-test-procedures.Memorandum February 16, 2016 Page 4

reporting the releases to determ ine how to report and how to ap ply the TRI guidance), unlike EPA’s methodology for calculating pollutant loadings from DMR d ata described above.

In general, for the annual 304m s creening-level review process, EPA uses the loads reported to TRI as is and does not make any adjustments to them . However, EPA may contact

facilities to confirm TRI discha rges for data that appear to be outliers. During these contacts, EPA may ask to review any monito ring data used to estimate rele ases or ask if all sampling results associated with the po llutant in question were below de tection. For only these outlier facilities, if EPA identifies th at all monitoring data for a sp ecific pollutant are non-detect, the load is zeroed, consistent wit h the methodology applied to the DMR data. EPA notes that this methodology is only applied to the small percentage of faciliti es that are contacted during the outlier review and have monitoring data.

1.2.3 Steam Electric Rulemaking Power Generating Non-Detect Methodology

For the Steam Electric Power Ge nerating rulemaking (for all was testreams), EPA’s estimates of baseline pollutant loadings and pollutant removals were derived using one half of the sample-specific QL (i.e., t he reporting limit) for all qual ified results (U-Qualified or JQualified), as illustrated in Figure 1 (U.S. EPA, 2015).

Figure 1. Steam Electric Methodo logy for Estimating Baseline Po llutant Loadings and

Removals

EPA was able to determine the QL for all qualified results in t he FGD data set that EPA used in pollutant loadings/removal calculations because the QL was available in the EPA sampling and industry-submitted data. In some instances, for fl y ash and bottom ash transport water, there were insufficient da ta available to determine the respective sample-specific QL. In these instances the data point was reported as a “less than” re sult along with a value, but EPA did not know whether the reported value was the sample-specific MDL or QL. For the purpose of estimating pollutant loadings and removals, EPA assumed the rep orted value was the QL and

used one-half that value in the calculations. For both FGD and ash, EPA only calculated wastestream-specific pollutant l oadings for pollutants with at least one detection in the

concentration dataset. EPA did not use data where all the data points in the data set were reported as qualified. EPA also completed a data quality review to deter mine if the data were acceptable for use in the pollutant loadings calculations. This review inc luded a specific review of acceptable analytical methods (U.S. EPA, 2015). QL (4.0) 0 MDL (1.2) 1⁄2 QL (2.0) J-Qualified Resul t U-Qualified ResultMemorandum February 16, 2016 Page 5

1.3 Data Limitations and Considerations

 The DMR data in ICIS-NDPES do notinclude the analytical method ; therefore, EPA cannot confirm the reported value for below detection results ( e.g., MDL, QL), unlike the

data reviewed and used in the St eam Electric Power Generating r ulemaking.

 For DMRs, facilities or EPA and s tate data entry personnel may enter zero for results below the MDL, and in those instan ces, zero is used in the load estimations. Facilities may also report averaged data on D MRs, which are also not flagg ed in the raw ICISNPDES data.

 EPA only contacts a small number of outlier facilities to confi rm discharges when reviewing loads for TRI. This is the only instance where EPA ma y zero a load based on non-detect monitoring data in TRI ( as it is not available in th e raw data and can only be collected during follow up). Duri ng these follow up calls, EPA may consider requesting the analytical method for the m onitoring results to compare to the list of methods at 40 CFR Part 136 to confirm that they a re sufficiently stringent an d that zeroing the loads is appropriate.

 Because the 304m annual review i s a screening-level review with a specific analytical purpose and objective, the cur rent methodology is appropriate s o that the rankings aren’t biased by pollutants that are a ll non-detect (i.e., dioxin).

1.4 References

1. U.S. EPA. 2009. Technical Support Do cument for the Annual Revie w of Existing

Effluent Guidelines and Identific ation of Potential New Point S ource Categories. EPA821-R-09-007. Washington, D.C. (Oc tober). EPA-HQ-OW-2008-0517-0 515.

2. U.S. EPA. 2015. Incremental Costs and Pollutant Removals for th e Final Effluent

Limitations Guidelines and Standard s for the Steam Electric Pow er Generating Point Source Category. Washington, D.C. (September). EPA-HQ-OW-2009-0 819-6472.

3. U.S. EPA. 2016. 2015 Annual Effluent Guidelines Review Report . Washington, D.C. (June). EPA-821-R-16-002. E PA-HQ-OW-2015-0665. DCN 08209.