## MEMORANDUM

**TO:** Steam Electric Rulemaking Record **FROM:** Daisy

Wang , ERG TJ Finseth, ERG **DATE:** April 19 , 201 3 **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 (ELG s ) 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 ELG s . When developing the effluent limitations included in the proposed ELG s , 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 wastestream 1 

### . EPA then evaluates which of the POCs to set effluent limits based on f

actors 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. I** **NTRODUCTION** 

### 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. C onstituents that EPA identified as POCs were used as the starting point to identify which pollutants to set effluent limitations

. **2. D**  **ATA** 

### U **SED** 

### F **OR** 

### POC **A NALYSIS**  

### 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 b y the industry. The analytes selected for analys is 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 analy tical data f

or 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.
 

### A sh 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 l andfills c ontaining c ombustion 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 waste s : EPA collected characterization data associated with chemical and nonchemical metal cleaning wastes as par t 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**  **A NALYSIS**  

### M**ETHODOLOGY** 

### 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 pres ent in the wastestream at quantifiable levels may be sufficient to identify

a pollutant as a pollutant of concern. Additionally, in past effluent guidelines rulemaking s, EPA has determined that a lower threshold (e.g., 5 times the baseline value) was the a ppropriate criterion for identifying pollutants of concern. For example, s ee 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 identifi ed for the analytical method for a pollutant. For the CWT ELG s , 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 ELG s used the instrument detection limit for EPA Method 1620 as the basis for the metals baseline value s, with some exceptions. For the steam electric proposed ELG s , EPA analyz ed 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 analys is. 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 S team E lectric ELG s .

**Table 3** 
**- 1**  **. Baseline Values fo**  **r Steam Electric Industry POCs**

**POC Unit**  **Baseline Value Classicals or**  **C onventionals**  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 Page 4 **Table 3** 
**- 1**  **. Baseline Values fo**  **r 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 **Me tals**  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

. 000 5 Moly bdenum 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 detecti on limit (MDL) for the analys is

. For some wastestreams (e.g., ash transport water), there were analy tes that did not have a baseline value nor a sample

- specific MDL ; therefore, these analy tes were not included in the analys is 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.

### Memorandum

April 19, 2013 Page 5 **4. R** **ESULTS** 

### 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 Poll**  **utants of Concern** EPA identified 3 5 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 re sults 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 Analysi**  **s 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 Page 6 **Table 4** 
**- 1**  **. POC Analysi**  **s 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 Moly bdenum 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 Grease a Total Suspended Solids

Priority Pollutants Antimony Arsenic Beryllium Cadmium Chromium Copper Cyanide Lead Mercury Nickel

### Memorandum

April 19, 2013 Page 7 **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 Moly bdenum 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 oi l 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 analyz ed for each pollutant in ash transport water, the numb er of sample results that were not detected above the quantitation limit, and the percentage of sample results that were detected at a concentration greater tha n 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 b y 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, confirma tion 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 o f concern. Table 4

- 4 lists the POCs identified for ash transport water.

**Table 4** 
**- 3**  **. POC**  **Analysi s 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 Page 9 **Table 4** 
**- 3**  **. POC**  **Analysi s 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 Moly bdenum 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 Grease a 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 Page 10 **Table 4** 
**- 4**  **. Pollutants of Concern**

**– Ash Transport Water** 

**Pollutant Group Pollutant of Concern** 

Nonconventional Pollutants Manganese Moly bdenum 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 typ e 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 POC s 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 1 6 POCs for combustion residual landfill leachate and 1 3 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 Analysi**  **s 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

### Memorandum

April 19, 2013 Page 11 **Table 4** 
**- 5**  **. POC Analysi**  **s 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 Moly bdenum 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 Page 12

**Table 4** 
**- 6**  **. Pollutants of Concern**

**– Landfill Leachate** 

**Pollutant Group Pollutant of Concern**  Conventional Pollutants Oil and Grease a Total Suspended Solids Priority Pollutants Arsenic Mercury Selenium

Nonconventional Pollutants Aluminum Boron Calcium Chlorides Iron Magnesium Manganese Moly bdenum 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**  **Analysi s 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 Page 13 **Table 4** 
**- 7**  **. POC**  **Analysi s 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 Moly bdenum 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 Page 14

**Table 4** 
**- 8**  **. Pollutants of Concern**

**– Im** **poundment Leachate** 

**Pollutant Group Pollutant of Concern**  Conventional Pollutants Oil and Grease a Priority Pollutants Arsenic Mercury

Nonconventional Pollutants Boron Calcium Chlorides Iron Magnesium Manganese Moly bdenum 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 analyz ed 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**  **. P OC Analysis for**  **Gasification Wastewater**

**Pollutant Number of**  **Samples Analyzed**  **Number of Non** 

**Detect Results Percentage**  **of Sam ple** 

**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 Page 15 **Table 4** 
**- 9**  **. P OC Analysis for**  **Gasification Wastewater**

**Pollutant Number of**  **Samples Analyzed**  **Number of Non** 

**Detect Results Percentage**  **of Sam ple** 

**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 Moly bdenum 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 Page 16

**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) s ystems, the activated carbon can either be injected upstream or downstream of the primary

particulate removal system. When the activated carbon is inje cted upstream of the primary particulate removal system, the FGMC waste is captured with the fly ash removed b y 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, ty pically a fabric filter baghouse, and residual fly ash that passes through the primary particulate removal system may

also be captured in the s ystem. The FGMC waste/fly ash from either of these configurations can be handled using either a wet sluicing s ystem or dry

handling s ystem. 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

April 19, 2013 Page 17
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** 

**– Fl** **ue Gas Mercury Control Wastewater**
**Pollutant Group Pollutant of Concern**  Conventional Pollutants Oil and Grease a Total Suspended Solids

Priority Pollutants Arsenic Beryllium Chromium Copper Lead Mercury Nickel Selenium Zinc

Nonc onventional Pollutants Aluminum Boron Barium Calcium Chloride Iron Manganese Moly bdenum 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 w ere 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 Nonc onventional Pollutants Iron Source: [U.S. EPA, 1974].

### Memorandum

April 19, 2013 Page 19 **5. R** **EFERENCES** 

### 1. Computer Sciences Corporation (CSC). 2013. Results of the ICP/MS Collision Cell Method Detection Limit S tudies in the Sy nthetic Flue Gas Desulfurization Matrix . (16 January). DCN SE03872

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