## MEMORANDUM

TO: Steam Electric ELG Rulemaking Record

FROM: Lydia Lambert, ERG

DATE: April 19, 2013

SUBJECT: Water Quality Model Supporting Documentation (DCN SE03888)

1.0 S UMMARY OF 

### S UPPORTING 

### D OCUMENTATION



### ERG is providing technical support to the U. S. Environmental Protection Agency (EPA) for development of revised effluent limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Point Source Category. In support of the development of revised ELGs, ERG developed the following resources to cal culate pollutant concentrations in the water column and sediment of the immediate receiving water and evaluate the impacts that receiving water concentrations pose to aquatic life and hu man health under the current profile and future profile 1 

### for the baseline and five regulatory op tions (Options 1, 2, 3, 4, and 5):

 Water Quality Model;

 Water Quality Model Comparisons Database;

 Water Quality Model Summary Tables Database; and

 Water Quality Model Summary Tables Spreadsheet.

The methodology of the water quality model unde r the current profile and future profile is presented in the following documentation:

 Water Quality Model: Plant and Receiv ing Water Characteristics Memorandum (DCN SE01955) – This memorandum specifies the methodology used to identify the
characteristics of the immediate receivi ng waters evaluated in the water quality
model.

 Pollutant Loadings Supporting Documentation Memorandum (DCN SE03887) – This memorandum identifies the supporting documen tation used to calculate the pollutant loadings evaluated in the water quality model.

1 Current profile includes waste streams generated by air pol lution controls that will likely be in operation at steam electric plants at the time EPA takes final action on this rulemaking. Future profile includes waste streams generated by future installations of air pollution controls at steam electric power plants that may result from some recently promulgated Clean Air Act requirements.

### Memorandum April 19, 2013 Page 2

 Final Environmental Assessment for the Pr oposed Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category (EA Report) (DCN SE01995) – Section 4.1.2 (Asse ssment of the Surface Water Exposure Pathway) of this report provides an overview of the water quality model. Appendix C (Water Quality Model Methodology) of this report presents the model equations, input values, pollutant benchmarks , and methodology limitations/assumptions.

ERG did not calculate pollutant concentrations in the water column and sediment of the immediate receiving water for Options 3a, 3b, and 4a using the water quality supporting documentation listed above. The methodology used for these three regulatory options is presented in Appendix G (Methodology for N on-Modeled Options) of the EA Report.

1.1 Current Profile Analyses

The results of the water quality model under the current profile ar e presented in the following sections of the EA Report:

 Section 5.3.1 (Water Quality Impacts);

 Section 6.2 (Key Environmental Improvements);

 Section 6.3 (Pollutant-Specific Improvements); and

 Section 7 (Conclusions).

A comprehensive listing of the water qua lity model supporting documentation for the current profile is presented in Table 1-1 below. This table provi des the document control number (DCN), title, and abstract of each record item, and identifies wh ether the record item contains Confidential Business Information (CBI).

Table 1-1. Current Profile Water Quality Record Items

DCN Title (Date) Abstract CBI a
SE02993 Water Quality Model -
Current Profile - Baseline (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for baseline under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

SE02994 Water Quality Model - Current Profile - Option 1 (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for Option 1 under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

### Memorandum April 19, 2013 Page 3

Table 1-1. Current Profile Water Quality Record Items

DCN Title (Date) Abstract CBI a
SE02995 Water Quality Model - Current Profile - Option 2 (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for Option 2 under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

SE02996 Water Quality Model - Current Profile - Option 3 (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for Option 3 under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

SE02997 Water Quality Model - Current Profile - Option 4 (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for Option 4 under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

SE02998 Water Quality Model - Current Profile - Option 5 (082212) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone for Option 5 under the current profile. Generates inputs
for Wildlife and Human Health Models. Yes

SE02999 Water Quality Model Comparisons Database - Current Profile - Option 1 (082212) Database used to compare the Water Quality Model results between baseline and Option 1 under the current profile. Generates inputs for Water Quality Model Summary Tables
Database. Yes

SE03501 Water Quality Model Comparisons Database - Current Profile - Option 2 (082212) Database used to compare the Water Quality Model results between baseline and Option 2 under the current profile. Generates inputs for Water Quality Model Summary Tables
Database. Yes

SE03502 Water Quality Model Comparisons Database - Current Profile - Option 3 (082212) Database used to compare the Water Quality Model results between baseline and Option 3 under the current profile. Generates inputs for Water Quality Model Summary Tables
Database. Yes

SE03503 Water Quality Model Comparisons Database - Current Profile - Option 4 (082212) Database used to compare the Water Quality Model results between baseline and Option 4 under the current profile. Generates inputs for Water Quality Model Summary Tables
Database. Yes

SE03504 Water Quality Model Comparisons Database - Current Profile - Option 5 (082212) Database used to compare the Water Quality Model results between baseline and Option 5 under the current profile. Generates inputs for Water Quality Model Summary Tables
Database. Yes

### Memorandum April 19, 2013 Page 4

Table 1-1. Current Profile Water Quality Record Items

DCN Title (Date) Abstract CBI a
SE03505 Water Quality Model Summary Tables Database - Current Profile (082212) Database used to summarize the Water Quality Model results for baseline and regulatory options under the current profile. Generates the Water Quality Model Summary Tables Spreadsheet. No

SE03506 Water Quality Model Summary Tables Spreadsheet - Current Profile (082812) Spreadsheet that summarizes the Water Quality Model results for baseline and regulatory options under the current profile. No

a – Record items containing CBI have been removed from the public record.



### 1.2 Future Profile Analyses

The results of the water quality model under the future profile are presented in the Flue Gas Desulfurization Future Profile Sensitivity Analysis Memorandum (DCN SE01989). A comprehensive listing of the wate r quality model supporting documentation for the future profile is presented in Table 1-2 below.

Table 1-2. Future Profile Water Quality Record Items

DCN Title (Date) Abstract CBI a
SE03509 Water Quality Model -
Future Profile – Questionnaire and IPM (091112) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone under baseline future profile. This scope includes plants with predicted future air pollution control installations identified in the Integrated Planning (IPM) projections for the final Mercury and Air Toxics Standards (MATS) rule and EPA’s Questionnaire for the Steam Electric Power Generating Effluent Guidelines. Generates inputs for
Wildlife and Human Health Models. Yes

SE03510 Water Quality Model - Future Profile - IPM Only (091112) Database used to calculate th e total and dissolved receiving
water concentrations and total sediment concentrations and to identify pollutant concentrations that exceed benchmarks for aquatic life and human health in the immediate discharge zone under baseline future profile. This scope includes plants with predicted future air pollution control installations identified in the Integrated Planning (IPM) projections for the final Mercury and Air Toxics Standards (MATS) rule. Generates inputs for Wildlife and Human Health Models. Yes

a – Record items containing CBI have been removed from the public record.