MEMORANDUM

TO: Steam Electric Rulemaking Record

FROM: Daisy Wang, ERG

TJ Finseth, ERG

DATE: April 19, 2013

SUBJECT: Pollutants of Concern Methodology Memorandum

ERG is providing technical support to the U.S. Environmental Protection Agency’s Office of 

Water, Engineering and Analysis Division (EAD) for development of effluent limitations 

guidelines and standards (ELGs) for the Steam Electric Power Generating Industry. EPA, with 

the support of ERG, evaluated characterization data from each of the wastestreams targeted by

the proposed ELGs. When developing the effluent limitations included in the proposed ELGs, 

EPA first evaluates which pollutants are present in the wastewater and whether those pollutants 

are present at treatable levels. The pollutants that meet these criteria are identified as pollutants 

of concern (POC) for that specific wastestream1. EPA then evaluates which of the POCs to set 

effluent limits based on factors described in Section 11 of the Technical Development Document 

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

Point Source Category (Technical Development Document). This memorandum describes the 

approach used to identify POCs for each wastestream targeted in this rulemaking.

1. INTRODUCTION

Constituents present in combustion residual wastewater are primarily derived from the parent 

carbon feedstock (e.g., coal, petroleum coke). A number of these constituents have the potential 

to cause environmental harm depending on the mass pollutant loadings, wastewater 

concentration, and how organisms are exposed to them in the environment. Constituents that 

EPA identified as POCs were used as the starting point to identify which pollutants to set 

effluent limitations.

2. DATA USED FOR POC ANALYSIS

EPA conducted a field sampling program as part of the detailed study and rulemaking efforts for 

the Steam Electric ELGs to characterize the wastewater generated by the industry. The analytes 

selected for analysis reflect EPA’s current understanding of power plant wastewaters, including 

contributions from scrubber sorbents, treatment chemicals, and other sources. As part of the 

 

1 The POC analysis differs from evaluations of data used to estimate pollutant loadings and removals. The POC 

analysis is intended to identify those pollutants that are present in untreated wastewater at sufficient frequency and at 

treatable levels. The pollutant loadings and removals analysis, however, use effluent (e.g., end of pipe) 

concentrations for treated wastewater and may include loadings and incidental removals for pollutants that are not 

POCs.
Memorandum

April 19, 2013

Page 2

sampling program, EPA collected analytical data for FGD wastewater, ash transport wastewater, 

leachate from landfills and impoundments containing combustion residuals, and integrated 

gasification combined cycle (IGCC) wastewater.

EPA used the following data to identify POCs for each of the different wastestreams:

 FGD wastewater: EPA sampled untreated FGD wastewater from seven steam 

electric power plants operating FGD wastewater treatment systems as part of the 

rulemaking. EPA reviewed the untreated FGD wastewater data for these seven 

plants (total of seven sampling points and 28 samples) to identify the FGD 

wastewater POCs.

 Ash transport wastewater: EPA sampled untreated fly ash transport water at one 

plant during the steam electric detailed study. EPA reviewed the untreated fly ash 

transport water data from this plant (one sampling point and one sample) to 

identify the fly ash and bottom ash transport water POCs.

 Leachate from impoundments and landfills containing combustion residuals: EPA 

required a subset of plants to sample their impoundment and landfill leachate as 

part of the Questionnaire for the Steam Electric Power Generating Effluent 

Guidelines (Steam Electric Survey). EPA reviewed the untreated leachate data 

collected from the survey responses to identify POCs for impoundment and 

landfill leachate.

 Gasification wastewater: EPA sampled wastewater streams at two plants 

operating IGCC generating units as part of the Clean Water Action (CWA) 308 

sampling program. EPA reviewed the untreated wastewater data from these two 

steam electric power plants (total of five sampling points and 20 samples) to 

identify POCs for IGCC wastewater.

 Flue gas mercury control (FGMC) wastewater: EPA does not have any sampling 

data specific to FGMC wastewater. Based on responses to the Steam Electric 

Survey, EPA determined that the majority of plants generating FGMC wastewater 

are collecting the FGMC waste with the bulk of the fly ash removed from the flue 

gas, therefore EPA assumed that POCs associated with FGMC wastewater will be 

the same as those for fly ash transport water.

 Nonchemical metal cleaning wastes: EPA collected characterization data 

associated with chemical and nonchemical metal cleaning wastes as part of the 

1974 rulemaking. EPA used data from this previous rulemaking to identify POCs 

for nonchemical metal cleaning wastes.

For more information on the analytes evaluated in the EPA sampling program, refer to Section 3 

of the Technical Development Document.

3. POC ANALYSIS METHODOLOGY

EPA used the analytical data from the various sampling episodes (and other data sources) to 

identify the POCs considered for this rulemaking. From the list of analytes sampled, EPA

eliminated from consideration any pollutants that were never detected in the untreated 

wastewater samples, EPA then reviewed its data from untreated wastewater samples from 

individual wastestreams to identify pollutants detected at greater than or equal to 10 times the 

baseline value in at least 10 percent of all untreated process wastewater samples. This criterion 
Memorandum

April 19, 2013

Page 3

ensures that the pollutant was present in sufficient concentrations at sites where EPA evaluated 

treatment performance. This is used as a screening tool to identify those pollutants that are 

quantified in a wastestream at sufficient frequency and at treatable levels.

Using 10 times the baseline value as a screening threshold can facilitate evaluations of treatment 

system performance and efficacy, since it ensures the influent concentrations are high enough to 

more readily quantify the degree of pollutant removal resulting from treatment processes such as 

chemical or biological removal. However, the criterion is less applicable in cases where the 

technology basis results in complete removal of all pollutants present, such as would occur under 

the technology options considered for fly ash transport water, bottom ash transport water, and 

FGMC wastewater. For these “zero discharge” technologies, confirmation that the pollutant is 

present in the wastestream at quantifiable levels may be sufficient to identify a pollutant as a 

pollutant of concern. Additionally, in past effluent guidelines rulemakings, EPA has determined 

that a lower threshold (e.g., 5 times the baseline value) was the appropriate criterion for 

identifying pollutants of concern. For example, see Section 7 of the Technical Development 

Document for the Final Effluent Limitations Guidelines and Standards for the Meat and Poultry

Products Point Source Category (40 CFR 432) (EPA-821-R-04-011).

EPA used the baseline values that were developed for the 2000 Centralized Waste Treatment 

(CWT) Industry Effluent Limitations Guidelines for this analysis. The baseline values are 

generally equal to the nominal quantitation limit identified for the analytical method for a 

pollutant. For the CWT ELGs, the Agency made several exceptions to this general rule if it 

determined that reliable measurements of a pollutant could be made at a lower level, or if the 

nominal quantitation limit could not be reasonably achieved, or if a single baseline value had to 

be selected when a pollutant had multiple nominal quantitation limits. Generally, the CWT ELGs

used the instrument detection limit for EPA Method 1620 as the basis for the metals baseline 

values, with some exceptions. For the steam electric proposed ELGs, EPA analyzed the samples 

using EPA Methods 200.7, 200.8 with collision cell, and 1631E. Each of these methods is

capable of achieving quantitation limits that are lower than the baseline values from CWT. 

However, EPA used the CWT baseline values, in most cases, as a more conservative value for 

the analysis. EPA did make a couple of exceptions and used the minimum level for mercury

defined in EPA Method 1631E (i.e., 0.5 ng/L). Additionally, EPA used 2.0 μg/l for arsenic, 

which is based on a method detection limit study conducted by EPA [CSC, 2013]. Table 3-1

presents the baseline values used for the identification of POCs associated with the proposed 

Steam Electric ELGs.

Table 3-1. Baseline Values for Steam Electric Industry POCs

POC Unit Baseline Value

Classicals or Conventionals

Ammonia as Nitrogen μg/l 50.0

Biochemical Oxygen Demand μg/l 2,000.0

Chemical Oxygen Demand μg/l 5,000.0

Chloride μg/l 1,000.0

Nitrate/Nitrite μg/l 50.0

Total Cyanide μg/l 20.0

Total Dissolved Solids μg/l 10,000.0
Memorandum

April 19, 2013

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Table 3-1. Baseline Values for Steam Electric Industry POCs

POC Unit Baseline Value

Total Phosphorus μg/l 10.0

Total Sulfide μg/l 1,000.0

Total Suspended Solids μg/l 4,000.0

Metals

Aluminum μg/l 200.0

Antimony μg/l 20.0

Arsenic μg/l 2.0

Barium μg/l 200.0

Beryllium μg/l 5.0

Boron μg/l 100.0

Cadmium μg/l 5.0

Calcium μg/l 5,000.0

Chromium μg/l 10.0

Cobalt μg/l 50.0

Copper μg/l 25.0

Iron μg/l 100.0

Lead μg/l 50.0

Magnesium μg/l 5,000.0

Manganese μg/l 15.0

Mercury μg/l 0.0005

Molybdenum μg/l 10.0

Nickel μg/l 40.0

Phosphorus μg/l 1,000.0

Potassium μg/l 1,000.0

Selenium μg/l 5.0

Sodium μg/l 5,000.0

Sulfur μg/l 1,000.0

Thallium μg/l 10.0

Titanium μg/l 5.0

Vanadium μg/l 50.0

Zinc μg/l 20.0

Source: Development Document for Effluent Limitations Guidelines and Standards for the Centralized Waste 

Treatment Industry, [EPA, 2000]; EPA Method 1631E, [CSC, 2013].

For some pollutants, EPA did not have a baseline value identified from the 2000 CWT ELGs. 

For these pollutants, EPA used the sample-specific method detection limit (MDL) for the 

analysis. For some wastestreams (e.g., ash transport water), there were analytes that did not have

a baseline value nor a sample-specific MDL; therefore, these analytes were not included in the 

analysis and were not identified as a POC for the specific wastestream. Using the criteria 

described above, EPA developed lists of POCs for each fuel combustion wastewater: FGD 

wastewater, fly ash transport water, bottom ash transport water, landfill combustion residual 

leachate, impoundment combustion residual leachate, FGMC wastewater, and gasification 

wastewater.
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April 19, 2013

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4. RESULTS

This section of the memorandum describes the results of the POC analysis for each of the 

wastestreams for which EPA is proposing revisions to the ELG.

4.1.1 FGD Wastewater Pollutants of Concern

EPA identified 35 POCs for FGD wastewater using the criteria presented in Section 3. Table 4-1

presents the number of samples analyzed for each pollutant in FGD wastewater, the number of 

sample results that were not detected above the quantitation limit, and the percentage of sample 

results that were detected at a concentration greater than ten times the baseline value. Table 4-2

lists the POCs identified for FGD wastewater.

Table 4-1. POC Analysis for FGD Wastewater

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of 

Sample Results >10x 

Baseline Value

Identified 

as a POC?

Conventional Pollutants

Biochemical Oxygen Demand 28 5 4% No

Total Suspended Solids 28 0 100% Yes

Priority Pollutants

Antimony 28 7 18% Yes

Arsenic 28 0 100% Yes

Beryllium 28 4 29% Yes

Cadmium 28 7 43% Yes

Chromium 28 0 100% Yes

Copper 28 0 71% Yes

Cyanide, Total 28 4 57% Yes

Lead 28 0 43% Yes

Mercury 28 0 57% Yes

Nickel 28 0 71% Yes

Selenium 28 0 100% Yes

Silver 28 27 4% No

Thallium 28 3 43% Yes

Zinc 28 0 100% Yes

Nonconventional Pollutants

Aluminum 28 0 100% Yes

Ammonia 28 7 75% Yes

Barium 28 0 43% Yes
Memorandum

April 19, 2013

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Table 4-1. POC Analysis for FGD Wastewater

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of 

Sample Results >10x 

Baseline Value

Identified 

as a POC?

Boron 28 0 100% Yes

Calcium 28 0 100% Yes

Chemical Oxygen Demand 28 1 96% Yes

Cobalt 28 0 43% Yes

Iron 28 0 100% Yes

Magnesium 28 0 100% Yes

Manganese 28 0 100% Yes

Molybdenum 28 3 71% Yes

Nitrate Nitrite as N 28 0 100% Yes

Nitrogen, Kjeldahl 28 0 100% Yes

Phosphorus, Total 28 10 29% Yes

Sodium 28 0 71% Yes

Sulfate 28 0 100% Yes

Tin 28 28 0% No

Titanium 28 0 100% Yes

Total Dissolved Solids 28 0 100% Yes

Vanadium 28 0 61% Yes

Chloride 28 0 100% Yes

Source: EPA Sampling Data, [ERG, 2012b – 2012h]; Progress Energy Data, [NCDENR, 2011]; Duke Energy Data, 

[Duke Energy, 2011a-2011b].

Table 4-2. Pollutants of Concern – FGD Wastewater

Pollutant Group Pollutant of Concern

Conventional Pollutants

Oil and Greasea

Total Suspended Solids

Priority Pollutants

Antimony

Arsenic

Beryllium

Cadmium

Chromium

Copper

Cyanide

Lead

Mercury

Nickel
Memorandum

April 19, 2013

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Table 4-2. Pollutants of Concern – FGD Wastewater

Pollutant Group Pollutant of Concern

Priority Pollutants

Selenium

Thallium

Zinc

Nonconventional Pollutants

Aluminum

Ammonia

Barium

Boron

Calcium

Chemical Oxygen Demand

Chloride

Cobalt

Iron

Magnesium

Manganese

Molybdenum

Nitrate/Nitrite

Nitrogen, Kjeldahl

Phosphorus

Sodium

Sulfate

Titanium

Total Dissolved Solids

Vanadium

Source: [ERG, 2012b – 2012h].

a – EPA did not analyze its field sampling data for oil and grease. Rather, since the existing steam electric ELGs 

currently contain BPT limitations applicable to FGD wastewater for oil and grease, EPA already has data from the 

existing rulemaking demonstrating oil and grease is also a pollutant of concern in FGD wastewater.

4.1.2 Ash Transport Water Pollutants of Concern

EPA identified 24 POCs using the criteria presented in Section 3. Table 4-3 presents the number 

of samples analyzed for each pollutant in ash transport water, the number of sample results that 

were not detected above the quantitation limit, and the percentage of sample results that were 

detected at a concentration greater than ten times the baseline value.

EPA also identified selenium as a POC for fly ash transport water based on a study conducted at 

Belews Lake that linked fish kills to selenium accumulation in the lake associated with 

discharges from a power plant, as well as other documented instances of harm caused by 

discharges of selenium in ash transport water [Lemly, 1985]. As discussed above in Section 3,

the criterion EPA used as a screening tool to identify pollutants of concern is less applicable in 

cases where the technology basis results in complete removal of all pollutants present, such as 

would occur under the technology options considered for fly ash transport water, bottom ash 
Memorandum

April 19, 2013

Page 8

transport water, and FGMC wastewater. For these “zero discharge” technologies, confirmation 

that the pollutant is present in the wastestream at quantifiable levels may be sufficient to identify

a pollutant as a pollutant of concern. Based on the information in the record for selenium in ash 

transport water, EPA identified it as a pollutant of concern. Table 4-4 lists the POCs identified 

for ash transport water.

Table 4-3. POC Analysis for Ash Transport Water

Pollutant

Number of 

Samples 

Analyzed

Number of

Non Detect 

Results

Percentage of 

Sample Results >10x 

Baseline Value

Identified as a 

POC?

Conventional Pollutants

Total Suspended Solids 1 0 100% Yes

Biochemical Oxygen Demand 1 0 0% No

Priority Pollutants

Antimony 2 1 0% No

Arsenic 2 0 100% Yes

Beryllium 1 0 100% Yes

Cadmium 2 0 0% No

Chromium 2 0 100% Yes

Copper 2 0 100% Yes

Lead 2 0 50% Yes

Mercury 2 0 100% Yes

Nickel 2 0 50% Yes

Selenium 2 2 0% No

Silver 2 2 0% No

Thallium 2 1 0% No

Zinc 2 0 100% Yes

Nonconventional Pollutants

Aluminum 1 0 100% Yes

Ammonia 1 0 0% No

Barium 1 0 100% Yes

Boron 1 0 100% Yes

Calcium 1 0 100% Yes

Chloride 1 0 100% Yes

Cobalt 1 0 0% No

Hexane Extractable Material 1 0 No Baseline or MDL No Baseline or MDL

Iron 1 0 100% Yes
Memorandum

April 19, 2013

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Table 4-3. POC Analysis for Ash Transport Water

Pollutant

Number of 

Samples 

Analyzed

Number of

Non Detect 

Results

Percentage of 

Sample Results >10x 

Baseline Value

Identified as a 

POC?

Magnesium 1 0 0% No

Manganese 1 0 100% Yes

Molybdenum 1 0 100% Yes

Nitrate/Nitrite 1 0 100% Yes

Nitrogen, Kjeldahl 1 0 No Baseline or MDL No Baseline or MDL

Phosphorus, Total 1 0 0% No

SGT-HEM 1 0 0% No

Sodium 1 0 100% Yes

Sulfate 1 0 No Baseline or MDL No Baseline or MDL

Tin 1 1 0% No

Titanium 1 0 100% Yes

Total Dissolved Solids 1 0 100% Yes

Vanadium 1 0 100% Yes

Yttrium 1 0 100% Yes

Source: Cardinal Sampling Data, [ERG, 2008].

Table 4-4. Pollutants of Concern – Ash Transport Water

Pollutant Group Pollutant of Concern

Conventional Pollutants

Oil and Greasea

Total Suspended Solids

Priority Pollutants

Arsenic

Beryllium

Chromium

Copper

Lead

Mercury

Nickel

Selenium

Zinc

Nonconventional Pollutants

Aluminum

Barium

Boron

Calcium

Chloride

Iron
Memorandum

April 19, 2013

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Table 4-4. Pollutants of Concern – Ash Transport Water

Pollutant Group Pollutant of Concern

Nonconventional Pollutants

Manganese

Molybdenum

Nitrate/Nitrite

Sodium

Titanium

Total Dissolved Solids

Vanadium

Yttrium

Source: Cardinal Sampling Data, [ERG, 2008].

a – EPA did not analyze its field sampling data for oil and grease. Rather, since the existing steam electric ELGs 

currently contain BPT limitations applicable to fly ash transport water for oil and grease, EPA already has data from 

the existing rulemaking demonstrating oil and grease is also a pollutant of concern in fly ash transport water.

Constituents present in ash, and therefore ash transport water, are primarily derived from the type 

of coal/petroleum coke burned; therefore, EPA expects that the bottom ash transport water will 

have the same constituents that are found in the fly ash transport water. For this reason, EPA 

assumed that the POCs for bottom ash transport water are identical to those of fly ash transport 

water.

4.1.3 Impoundment and Landfill Leachate Pollutants of Concern

EPA identified 16 POCs for combustion residual landfill leachate and 13 POCs for combustion 

residual impoundment leachate, using the criteria presented in Section 3. Table 4-5 presents the 

number of samples analyzed for each pollutant in the combustion residual landfill leachate, the 

number of sample results that were not detected above the quantitation limit, and the percentage 

of sample results that were detected at a concentration greater than ten times the baseline value.

Table 4-6 lists the POCs identified for combustion residual landfill leachate. Table 4-7 presents 

the number of samples analyzed for each pollutant in the combustion residual impoundment 

leachate, the number of sample results that were not detected above the quantitation limit, and 

the percentage of sample results that were detected at a concentration greater than ten times the 

baseline value. Table 4-8 lists the POCs identified for combustion residual impoundment 

leachate.

Table 4-5. POC Analysis for Landfill Leachate

Pollutant

Number of 

Samples 

Analyzed

Number of 

Non Detect 

Results

Percentage of 

Sample Results

>10x Baseline

Identified as 

a POC?

Conventional Pollutants

Total suspended solids (TSS) 225 91 12% Yes

Priority Pollutants

Antimony 226 133 0% No
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April 19, 2013

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Table 4-5. POC Analysis for Landfill Leachate

Pollutant

Number of 

Samples 

Analyzed

Number of 

Non Detect 

Results

Percentage of 

Sample Results

>10x Baseline

Identified as 

a POC?

Arsenic 233 49 46% Yes

Beryllium 225 200 0% No

Cadmium 231 110 7% No

Chromium 231 140 7% No

Copper 233 121 0% No

Lead 223 174 0% No

Mercury 231 46 48% Yes

Nickel 229 65 4% No

Selenium 233 42 28% Yes

Silver 222 211 1% No

Thallium 225 152 0% No

Zinc 226 107 7% No

Nonconventional Pollutants

Aluminum 225 72 12% Yes

Barium 233 8 0% No

Boron 233 6 86% Yes

Calcium 233 2 90% Yes

Chlorides 232 6 81% Yes

Cobalt 229 94 2% No

Iron 227 58 26% Yes

Magnesium 233 6 37% Yes

Manganese 231 26 64% Yes

Molybdenum 233 19 65% Yes

Sodium 233 2 63% Yes

Sulfate 232 1 98% Yes

Tin 224 217 0% No

Titanium 223 167 5% No

Total dissolved solids (TDS) 232 0 95% Yes

Vanadium 229 100 5% No

Source: Steam Electric Survey, [ERG, 2012a];
Memorandum

April 19, 2013

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Table 4-6. Pollutants of Concern – Landfill Leachate

Pollutant Group Pollutant of Concern

Conventional Pollutants

Oil and Greasea

Total Suspended Solids

Priority Pollutants

Arsenic

Mercury

Selenium

Nonconventional Pollutants

Aluminum

Boron

Calcium

Chlorides

Iron

Magnesium

Manganese

Molybdenum

Sodium

Sulfate

Total Dissolved Solids

Source: Steam Electric Survey, [ERG, 2012a];

a – The landfill leachate samples were not analyzed for oil and grease (O&G). Rather, since the existing steam 

electric ELGs currently contain BPT limitations applicable to combustion residual leachate for O&G, EPA already 

has data from the existing rulemaking demonstrating O&G is also a pollutant of concern in combustion residual 

leachate.

Table 4-7. POC Analysis for Impoundment Leachate

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of 

Sample Results

>10x Baseline

Identified as 

a POC?

Conventional Pollutants

Total suspended solids (TSS) 85 38 5% No

Priority Pollutants

Antimony 85 54 0% No

Arsenic 81 14 28% Yes

Beryllium 81 64 0% No

Cadmium 81 41 0% No

Chromium 81 65 0% No

Copper 84 32 0% No

Lead 81 52 0% No

Mercury 82 19 11% Yes
Memorandum

April 19, 2013

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Table 4-7. POC Analysis for Impoundment Leachate

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of 

Sample Results

>10x Baseline

Identified as 

a POC?

Nickel 85 10 0% No

Selenium 81 43 5% No

Silver 81 78 0% No

Thallium 81 50 0% No

Zinc 81 16 5% No

Nonconventional Pollutants

Aluminum 85 30 0% No

Barium 85 0 0% No

Boron 85 0 56% Yes

Calcium 85 0 89% Yes

Chlorides 85 0 75% Yes

Cobalt 85 19 0% No

Iron 85 9 39% Yes

Magnesium 85 0 25% Yes

Manganese 85 1 75% Yes

Molybdenum 85 18 22% Yes

Sodium 85 0 27% Yes

Sulfate 85 0 96% Yes

Tin 81 76 5% No

Titanium 81 52 1% No

Total dissolved solids (TDS) 85 0 99% Yes

Vanadium 81 66 0% No

Source: Steam Electric Survey, [ERG, 2012a].
Memorandum

April 19, 2013

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Table 4-8. Pollutants of Concern – Impoundment Leachate

Pollutant Group Pollutant of Concern

Conventional Pollutants Oil and Greasea

Priority Pollutants

Arsenic

Mercury

Nonconventional Pollutants

Boron

Calcium

Chlorides

Iron

Magnesium

Manganese

Molybdenum

Sodium

Sulfate

Total Dissolved Solids

Source: Steam Electric Survey, [ERG, 2012a]

a – The impoundment leachate samples were not analyzed for O&G. Rather, since the existing steam electric ELGs 

currently contain BPT limitations applicable to combustion residual leachate for O&G, EPA already has data from 

the existing rulemaking demonstrating O&G is also a pollutant of concern in combustion residual leachate.

4.1.4 Gasification Pollutants of Concern

EPA identified 20 POCs for gasification wastewater using the criteria presented in Section 3.

Table 4-9 presents the number of samples analyzed for each pollutant in gasification wastewater, 

the number of sample results that were not detected above the quantitation limit, and the 

percentage of sample results that were detected at a concentration greater than ten times the 

baseline value. Table 4-10 lists the POCs identified for gasification wastewater.

Table 4-9. POC Analysis for Gasification Wastewater

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of Sample

Results >10x Baseline POC?

Conventional Pollutants

Total Suspended Solids 20 13 0% No

Biochemical Oxygen Demand 20 5 55% Yes

Priority Pollutants

Antimony 20 16 20% Yes

Arsenic 20 10 40% Yes

Beryllium 20 16 0% No

Cadmium 20 18 0% No

Chromium 20 16 0% No
Memorandum

April 19, 2013

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Table 4-9. POC Analysis for Gasification Wastewater

Pollutant

Number of 

Samples 

Analyzed

Number of Non 

Detect Results

Percentage of Sample

Results >10x Baseline POC?

Copper 20 16 0% No

Cyanide, Total 20 6 70% Yes

Lead 20 13 0% No

Mercury 20 7 65% Yes

Nickel 20 12 20% Yes

Selenium 20 0 95% Yes

Silver 20 20 0% No

Thallium 20 9 10% Yes

Zinc 20 16 0% No

Nonconventional Pollutants

Aluminum 20 15 25% Yes

Ammonia 20 0 100% Yes

Barium 20 16 0% No

Boron 20 3 80% Yes

Calcium 20 8 0% No

Chemical Oxygen Demand 20 5 75% Yes

Chloride 20 0 100% Yes

Cobalt 20 20 0% No

Iron 20 3 45% Yes

Magnesium 20 12 0% No

Manganese 20 15 10% Yes

Molybdenum 20 18 0% No

Nitrate Nitrite as N 20 14 20% Yes

Nitrogen, Kjeldahl 20 2 90% Yes

Phosphorus, Total 20 1 0% No

Sodium 20 4 80% Yes

Sulfate 20 11 45% Yes

Tin 20 20 0% No

Titanium 20 18 0% No

Total Dissolved Solids 20 2 90% Yes

Vanadium 20 9 0% No

Source: CWA 308 Monitoring Data, [ERG, 2012i].
Memorandum

April 19, 2013

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Table 4-10. Pollutants of Concern – Gasification Wastewater

Pollutant Group Pollutant of Concern

Conventional Pollutants Biochemical Oxygen Demand

Priority Pollutants

Antimony

Arsenic

Cyanide

Mercury

Nickel

Selenium

Thallium

Nonconventional Pollutants

Aluminum

Ammonia

Boron

Chemical Oxygen Demand

Chloride

Iron

Manganese

Nitrate/Nitrite

Nitrogen, Kjeldahl

Sodium

Sulfate

Total Dissolved Solids

Source: CWA 308 Monitoring Data, [ERG, 2012i]

4.1.5 Flue Gas Mercury Control Wastewater Pollutants of Concern

As described in Section 6.4 of the Technical Development Document, for activated carbon 

injection (ACI) systems, the activated carbon can either be injected upstream or downstream of 

the primary particulate removal system. When the activated carbon is injected upstream of the 

primary particulate removal system, the FGMC waste is captured with the fly ash removed by 

the system. When the activated carbon is injected downstream of the primary particulate removal 

system, the FGMC waste must be collected in a separate particulate removal system, typically a 

fabric filter baghouse, and residual fly ash that passes through the primary particulate removal 

system may also be captured in the system.

The FGMC waste/fly ash from either of these configurations can be handled using either a wet 

sluicing system or dry handling system. Based on process knowledge and engineering judgment, 

EPA concluded that the pollutants of concern for FGMC wastewater are likely to be identical to 

the pollutants of concern identified for fly ash transport water. This is due to the fact that, when 

activated carbon is injected into the flue gases, the carbon intermixes with the fly ash particles, 

and then the commingled mixture of activated carbon (which adsorbs mercury and other 

pollutants from the flue gases) and fly ash particles is captured together and transferred to the 

FGMC wastewater. Based on this conclusion, EPA identified 25 POCs associated with FGMC 
Memorandum

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wastewater. Table 4-11 lists the POCs identified for FGMC wastewater, which is the same as the 

list for fly ash transport water.

Table 4-11. Pollutants of Concern – Flue Gas Mercury Control Wastewater

Pollutant Group Pollutant of Concern

Conventional Pollutants

Oil and Greasea

Total Suspended Solids

Priority Pollutants

Arsenic

Beryllium

Chromium

Copper

Lead

Mercury

Nickel

Selenium

Zinc

Nonconventional Pollutants

Aluminum

Boron

Barium

Calcium

Chloride

Iron

Manganese

Molybdenum

Nitrate/Nitrite

Sodium

Titanium

Total Dissolved Solids

Vanadium

Yttrium

Source: [ERG, 2008].

4.1.6 Nonchemical Metal Cleaning Wastes Pollutants of Concern

As part of the 1974 rulemaking, EPA collected characterization data associated with chemical 

and nonchemical metal cleaning wastes. Based on the data collected during that rulemaking, 

EPA determined that TSS, oil & grease (O&G), copper, and iron were pollutants of concern for 

metal cleaning waste warranting regulation. As such, EPA set BPT limitations for these four 

pollutants in discharges of metal cleaning wastes, including both nonchemical and chemical 

cleaning wastes. For additional information regarding the pollutants that may be present in 

nonchemical metal cleaning wastes, see the 1974 Development Document for Effluent 

Limitations Guidelines and New Source Performance Standards for the Steam Electric Power 

Generating Point Source Category [U.S. EPA, 1974]. 
Memorandum

April 19, 2013

Page 18

Based on this assessment, EPA determined that TSS, O&G, copper, and iron are POCs for 

nonchemical metal cleaning wastes. Table 4-12 presents the four POCs for nonchemical metal 

cleaning wastes. 

Table 4-12. Pollutants of Concern – Nonchemical Metal Cleaning Wastes

Pollutant Group Pollutant of Concern

Priority Pollutants Copper

Conventional Pollutants

Total Suspended Solids

Oil & Grease

Nonconventional Pollutants Iron

Source: [U.S. EPA, 1974].
Memorandum

April 19, 2013

Page 19

5. REFERENCES

1. Computer Sciences Corporation (CSC). 2013. Results of the ICP/MS Collision Cell 

Method Detection Limit Studies in the Synthetic Flue Gas Desulfurization Matrix. (16 

January). DCN SE03872.

2. Duke Energy. 2011a Industry Provided Sampling Data from Duke Energy’s Belews 

Creek Steam Station. (17 August). DCN SE01808.

3. Duke Energy. 2011b Industry Provided Sampling Data from Duke Energy’s Allen Steam 

Station. (17 August). DCN SE01809.

4. Eastern Research Group (ERG). 2008. Final Sampling Episode Report, Buckeye Power 

Company’s Cardinal Power Plant. (August 26). DCN SE02107.

5. Eastern Research Group (ERG). 2012a. Steam Electric Technical Questionnaire Database 

(“Steam Electric Survey”). (Date). DCN SE01958.

6. Eastern Research Group (ERG). 2012b. Final Sampling Episode Report, Duke Energy

Carolinas’ Belews Creek Steam Station. (13 April). DCN SE01305.

7. Eastern Research Group (ERG). 2012c. Final Sampling Episode Report, We Energies’ 

Pleasant Prairie Power Plant. (13 April). DCN SE01306.

8. Eastern Research Group (ERG). 2012d. Final Sampling Episode Report, Duke Energy

Miami Fort Station. (13 April). DCN SE01304.

9. Eastern Research Group (ERG). 2012e. Final Sampling Episode Report, Duke Energy

Carolinas’ Allen Steam Station. (13 April). DCN SE01307.

10. Eastern Research Group (ERG). 2012f. Final Sampling Episode Report, Mirant MidAtlantic, LLC’s Dickerson Generating Station. (13 April). DCN SE01308.

11. Eastern Research Group (ERG). 2012g. Final Sampling Episode Report, Allegheny

Energy’s Hatfield’s Ferry Power Station. (13 April). DCN SE01310.

12. Eastern Research Group (ERG). 2012h. Final Sampling Episode Report, RRI Energy’s 

Keystone Generating Station. (13 April). DCN SE01309.

13. Eastern Research Group (ERG). 2012i. Final Power Plant Monitoring Data Collected 

Under Clean Water Act Section 308 Authority (“CWA 308 Monitoring Data”). (30 May). 

DCN SE01326.

14. NCDENR. 2011. North Carolina Department of Environment and Natural Resources 

(NCDENR). State Provided Sampling Data from North Carolina’s Progress Energy

Roxboro Plant. (26 June). DCN SE01812.

15. U.S. EPA. 1974. Development Document for Effluent Limitations Guidelines and New 

Source Performance Standards for the Steam Electric Power Generating Point Source 

Category. Washington, D.C. (October). DCN SE02917.
Memorandum

April 19, 2013

Page 20

16. U.S. EPA, 2000. Development Document for Effluent Limitations Guidelines and 

Standards for the Centralized Waste Treatment Industry. (August). DCN SE02920.