MEMORANDUM 

TO: Steam Electric Rulemaking Record

FROM: Dan-Tam Nguyen, ERG 

DATE: September 30, 2015

SUBJECT: Development Memorandum for the Steam Electric Analytical Database for 

the Final Rule 

1.0 INTRODUCTION

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

Office of Water, Engineering and Analysis Division (EPA) for development of effluent 

limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Industry. 

ERG developed the Steam Electric Analytical Database for the Final Rule (DCN SE05359) 

(hereafter, “the analytical database”), which is a compilation of the analytical data for 

wastestreams evaluated as part of the final rule. This database includes data gathered during the 

rulemaking, including data from EPA field sampling activities, responses to the Questionnaire 

for the Steam Electric Power Generating Effluent Guidelines (Steam Electric Survey) (DCN 

SE05903), industry-submitted data, and other data collected from technical sources. This 

memorandum describes ERG’s general data quality review criteria, the data ERG deemed 

acceptable for inclusion in the database, and the data ERG used for engineering analyses. In 

addition, this memorandum describes any necessary data processing procedures and/or data 

editing criteria to ready the data for subsequent analyses. 

2.0 GENERAL DATA QUALITY REVIEW PROCEDURES

 The main sources of data for the rulemaking are EPA/ERG site visit and sampling event 

program data, data collected from the Steam Electric survey, and secondary (or existing) data. 

Secondary data come from sources that already exist and can be used in support of analyses 

outside the original intent of the data. These sources include plant monitoring data, other 

monitoring data (such as EPA’s CWA Section 308 Letters), articles and technical papers, 

industry/vendor telephone query data, and internet information. To ensure that the analytical data 

collected for the Steam Electric Rulemaking are of the quality necessary to support EPA in 

revising the existing ELGs for this industry category, ERG subjected site visit and sampling 

event data, data collected from the Steam Electric Survey, and secondary data to the data quality 

review criteria outlined for each of these data source types in the Quality Assurance Project Plan 

for the Steam Electric Effluent Guidelines Rulemaking (“QAPP”) [ERG, 2013a]. For secondary 

data, ERG applied acceptance criteria to the analytical data based on use. For instance, analytical 

data from secondary sources may be used to identify pollutants of concern (POCs) for evaluated 

wastestreams, characterize in-process wastestreams and effluent discharges, evaluate wastewater 

treatment system performance, and estimate baseline pollutant discharges. 
In reviewing data sources for each of the wastestreams, ERG refined the general criteria 

described in the Quality Assurance Project Plan for the Steam Electric Effluent Guidelines 

Rulemaking (QAPP) to meet the needs of the engineering analyses for each wastestream. Section 

4 of this memorandum outlines the specific data sources for each wastestream and presents a 

discussion of data quality review procedures that were specific to individual wastestreams. 

3.0 DATABASE STRUCTURE 

 The analytical database was developed using Microsoft® Access 2007 software. It 

houses a total of six data tables, one representing the database dictionary description of tables 

(“Database Dictionary_Tables”), one representing the database dictionary description of fields 

(“Database Dictionary_FieldNames”), and the remaining four representing sample-specific 

analytical data for four wastestreams: flue gas desulfurization (FGD) wastewater, combustion 

residual leachate, gasification wastewater, and ash transport water (including fly, bottom, and 

combined ash transport water). Table 1 provides a summary of the tables included in the 

analytical database, including table names and their descriptions. This table is also included in 

the analytical database as “Database Dictionary_Tables.” 

Table 1. Summary of Final Analytical Database Tables

Table Name Description 

DataDictionary_Tables Dictionary describing database tables. 

DataDictionary_Field Names Dictionary describing database field names. 

FGD 

Data table containing data for FGD wastewater, including pond effluent, purge, and 

treatment effluent that ERG evaluated for FGD POC and pollutant loadings 

analyses. 

Ash 

Data table containing data for bottom ash transport water, fly ash transport water, 

and combined ash transport water that ERG evaluated for ash pollutant loadings 

analyses.a

Leachate 

Data table containing data for combustion residual leachate from landfills and 

surface impoundments that ERG evaluated for leachate POC and pollutant loadings 

analyses. 

Gasification 

Data table containing data for gasification wastewater that ERG evaluated for the 

gasification POC analysis. b

a – Data evaluated for the ash POC analysis are contained in two separate spreadsheets titled “Source Water Ash 

Treatment Analysis” (DCN SE04744) and “Pollutants of Concern Ash Treatment Analysis” (DCN SE04746). 

b – ERG did not evaluate gasification wastewater data for use in pollutant loadings analyses because EPA did not 

calculate pollutant loadings for this wastestream. 

 

3.1 General Data Format 

 With the exception of the data dictionary, each of the data tables included in this database 

is provided in a general data format consisting of the fields described in Table 2. The field names 

in this general data format are also included in the analytical database table “Database 

Dictionary_FieldNames.” For each data table, ERG included additional flags to further classify 

the analytical data for use in subsequent analyses for each wastestream. Not all data tables 

contain the same types of flags. Table 3 lists additional fields that are included in each of the data 

tables. 
Table 2. General Data Format for Analytical Database Tables

Field Name Field Description 

Record ID Unique number assigned to each record in the database. 

Plant ID Steam Electric Survey plant identification number. 

CBI Flag Indicator flag for noting the record is CBI. 

Plant Name Name of the steam electric generating plant. 

Episode 

Episode number assigned to each EPA sampling and CWA 308 sampling 

data event. 

Sample Number for each individual sample. 

Date Collected Date that the sample was collected from a particular wastestream. 

Lab Name Name of the analytical laboratory that analyzed the sample. 

Analyte Pollutant name. 

CAS_NO 

Chemical Abstracts Service (CAS) number specific to each chemical 

substance (analyte). 

Method 

Analytical method used to quantify the amount of the specified analyte in 

the sample. 

Procedure Form the analyte is in (e.g., Total, Dissolved, Filtrate, Solids). 

Units 

Concentration units for the amount, j-value concentrations, MDL, and RL 

fields. 

Non-Detect Indicator 

Flag for whether the sample was detected above the sample-specific 

quantitation limit (QL) or not. “D” represents detected values, or samples 

with concentrations above the QL. “ND” represents non-detected values, 

or samples with concentrations below the QL. 

Amount Concentration of the pollutant in the wastestream. 

J-Value Concentrations 

Maximum potential concentration of the analyte that is detected above the 

MDL but below the QL. 

Method detection limit (MDL) 

Minimum analyte concentration that can be demonstrated to be different 

from zero or a blank concentration at the 99% level of confidence. 

Reporting limit (RL) 

Sometimes referred to as quantitation limit (QL). Lowest concentration of 

an analyte that produces a quantitative result within specified limits of 

precision and bias. 

Dilution 

Dilution factor, which is the ratio of the final volume of the sample to the 

aliquot volume. 

Qualifiers 

Qualifier assigned by the analytical laboratory to flag measured analyte 

concentrations that are below the MDL or RL (e.g., “U” indicates the 

observation is below the MDL). 

Reason Notes about the sample and qualifier. 

Sample Point 

Either a sample point number or description of where the sample was 

collected. 

Sample Description 

Description about where the sample was collected in the wastewater 

treatment system and what type of wastewater. 

Type of Wastewater Description of the type of wastewater collected. 

Wastewater Classification Standardized classification for the type of wastewater collected. 

QA Sample Flag for duplicate samples and field blank samples. 

Type of Sampling 

Source of the sample (i.e., EPA Sampling, CWA 308 Sampling, Plant-Self 

Monitoring, EPRI). 

Sample Type 

Description of whether sample represents a single grab sample or 

composite of multiple samples. 
Table 3. Analytical Database Additional Fields

Field Name Data Tables 

Including Field Field Description 

Included in Loadings FGD, Leachate, Ash 

Indicator flag noting that the data were used in pollutant 

loadings analyses 

Included in POC Analysis 

FGD, Leachate, 

Gasification Indicator flag noting that the data were used in POC analyses 

Unit ID Leachate Unique identifier for landfill and surface impoundment units. 

Data Source Category Ash 

Broad descriptor of the data source (e.g., 1982 TDD, Detailed 

Study Ash Pond Sampling, EPRI Reports, Form 2c, Industry 

Submitted Data, and UWAG Public Comment) 

Data Classification Ash 

Indicator if the data point was accepted for use in specific ash 

analyses (e.g., loads, sensitivity analysis (SA), or excluded 

from all analyses) 

Project Notes Ash 

This field contains general notes about the sample that is not 

captured in the other fields but was considered during 

evaluation (i.e., why a result was excluded) 

3.2 Data Processing Procedures 

EPA collected data in a variety of different formats, including, but not limited to, Excel 

spreadsheets, Access databases, and hard copy reports. To facilitate the use of the data in 

subsequent engineering analyses, ERG processed the data sets into a general data format for the 

analytical database, as described in the previoius section. This section summarizes the data 

format and quality assurance procedures ERG used to maintain the integrity of the data during 

this database processing step. 

ERG evaluated each data source individually and determined the appropriate procedures 

to convert the original format to the general data format used in the analytical database. The 

general data format has a comprehensive list of fields that characterize each analytical data point. 

The data processing involved the addition or renaming of fields to match the general data format 

prior to importing the data source into the analytical database. Where the data source did not 

have information for these additional fields in the general data format, the import would leave 

these fields blank. ERG conducted a quality check of the data prior to and after importing the 

data into the analytical database to ensure that none of the data were altered or incorrectly 

updated. 

Although not required in the QAPP, ERG conducted a screening-level data review of 

secondary data against industry-provided analytical laboratory reports and subsequent 

correspondence with facilities to address inconsistencies in reporting. Where appropriate, ERG 

documented information that was added to the database separate from the original data set and 

based on these additional correspondences for the appropriate analytical results.

4.0 DATABASE CONTENTS

 This section describes the specific data sources considered for inclusion in the analytical 

database and the data selected for use in subsequent analyses. It also documents any processing 

procedures and corrections to the data collected and compiled for the rulemaking development. 
4.1 FGD Wastewater 

The review of data specific to FGD wastewater involved a number of steps to evaluate 

and process the data. This review and the development of specific data tables presented in the 

analytical database are detailed in a separate memo titled “Flue Gas Desulfurization (FGD) 

Wastewater Data - Development Memo for the Analytical Database for the Steam Electric 

Rulemaking” (DCN SE05880). 

4.2 Fly Ash and Bottom Ash Transport Water 

 The review of data specific to fly ash and bottom ash transport water involved a number 

of steps to evaluate and process the data. This review and the development of the ash table 

presented in the analytical database are detailed in a separate memo titled “Ash Analytical Data 

Review Memorandum” (DCN SE05567).

4.3 Combustion Residual Leachate 

 ERG reviewed data sources containing analytical data for combustion residual leachate. 

As part of the Steam Electric Survey, EPA requested that a subset of plants provide sampling 

data for untreated landfill and/or impoundment leachate collected at the plant. For more 

information on the Steam Electric Survey, including which plants were required to provide 

landfill and/or impoundment leachate sampling data, see Section 3 of the Technical Development 

Document for the Effluent Limitations Guidelines and Standards for the Steam Electric Power 

Generating Point Source Category (DCN SE05904). EPA received data from active and inactive 

landfills and impoundments at 39 plants. EPA did not receive or collect additional analytical data 

for combustion residual leachate. 

4.3.1 Data Included in the Analytical Database 

 Based on ERG’s review, ERG excluded data from retired or closed landfills and 

impoundments for use in subsequent analyses because combustion residual leachate from retired 

units is not representative of landfills and impoundments generating combustion residual 

leachate; therefore, not regulated in the final rule. The remaining data received through the 

Steam Electric Survey meet the data acceptance criteria outlined in the QAPP for questionnaire 

data. For this reason, ERG included in the analytical database data for combustion residual 

leachate (excluding those from retired landfills or surface impoundments) from the “Final Steam 

Electric Technical Questionnaire Database” (“survey database”) (DCN SE05903). 

4.3.2 Data Processing Activities 

 After extracting the relevant data from the Steam Electric Survey database, ERG 

processed the data into the general data format described in Section 3.1. The data processing 

required renaming field names from the survey database to make them consistent with the field 

names in Table 2. The reformatting step did not populate fields that did not exist in the original 

data set nor corrected any sample results. 

 
 ERG included an additional field, “Unit ID,” to indicate whether the combustion residual 

leachate data were collected from a landfill or surface impoundment. 

4.3.3 Data Acceptance Criteria 

ERG also generated two indicator flags to indicate whether the data were “Included in 

POC Analysis” and “Included in Loadings.” Error! Reference source not found. 4 presents the 

leachate data acceptance criteria for the POC analysis and loads analysis. 

Table 4. Leachate Data Acceptance Criteria 

Acceptance Criteria POC Analysis Loadings

Sample locations must be unambiguous and clearly described such that it can 

be categorized by type (e.g., landfill leachate or impoundment leachate) and 

level of treatment (e.g., untreated, partially treated). 

 

Sample must be representative of actual combustion residual leachate (not 

leachate from retired landfills or surface impoundments). 

 

Analytical data must represent individual sample results or plant-level 

average sample concentrations rather than average results representing 

multiple plants. 

 

Sample must be representative of full-scale, typical plant operations.  

Sample analysis must be completed using accepted analytical methods.a  

Data must not be duplicative of other accepted data.  

Sample data must provide sufficient information to identify units.  

Non-detect results were not accepted if no limit (e.g., DL, QL) was provided.  

Sample results must represent total (i.e., dissolved results were not accepted 

except for TDS).  

4.4 Gasification Wastewater 

 ERG reviewed data sources containing analytical data for gasification wastewater. As 

part of the CWA 308 monitoring program, ERG supported EPA in collecting data from two 

plants operating integrated gasification combined cycle (IGCC) systems. Both plants, Tampa 

Electric Company’s Polk Station (Polk) and Wabash Valley Power Association’s Wabash River 

Station (Wabash River), treat their gasification wastewater with an evaporation system. Both 

plants sampled the influent streams transferred to the evaporation system and the neutralized 

weak acid and steam stripper effluent streams, which are defined as gasification wastewater 

sreams. Each plant collected 10 samples. EPA did not receive or collect additional analytical data 

for gasification wastewater. 

4.4.1 Data Included in the Analytical Database 

 ERG reviewed data collected under EPA’s CWA 308 monitoring program and reported 

the results of the analytical data review in a separate memorandum titled “Final Power Plant 

Monitoring Data Collected Under Clean Water Act Section 308 Authority ("CWA 308 

Monitoring Data")” (DCN SE01326). The data meet the acceptance criteria for industrycollected data as outlined in the QAPP and confirmed in ERG’s review of the CWA 308 data. 
4.4.2 Data Processing Activities 

 ERG processed the data into the general data format described in Section 3.1. The data 

processing required renaming field names from the survey database to make consistent with the 

field names in Table 2. The reformatting step did not populate fields that did not exist in the 

original data set nor corrected sample results. 

 

4.4.3 Data Acceptance Criteria 

ERG also generated one indicator flag to indicate whether the data were “Included in 

POC Analysis.” Pollutant loadings analyses were not conducted for gasification wastewater. 

Error! Reference source not found. 4 presents the data acceptance criteria for the POC 

analysis. 

Table 4. Gasification Data Acceptance Criteria 

Acceptance Criteria POC Analysis

Sample locations must be unambiguous and clearly described such that it can be categorized 

by type (e.g., IGCC evaporator influent, steam stripper effluent, neutralized weak acid waste 

stream). 



Analytical data must represent individual sample results or plant-level average sample 

concentrations rather than average results representing multiple plants. 



Sample must be representative of full-scale, typical plant operations. 

Sample analysis must be completed using accepted analytical methods.a 

Data must not be duplicative of other accepted data. 

Sample data must provide sufficient information to identify units. 

Sample data were not accepted if it represented effluent from the evaporation technology. 

Non-detect results were not accepted if no limit (e.g., DL, QL) was provided. 

Sample results must represent total (i.e., dissolved results were not accepted except for 

TDS). 

5.0 REFERENCES 

ERG. 2013a. Quality Assurance Project Plan for the Steam Electric Effluent Guidelines 

Rulemaking. (5 April). DCN SE02951.