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MEMORANDUM

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

FROM:	James K. O'Connell, ERG 

DATE:	April 12, 2018

SUBJECT:	Oil and Gas Extraction Wastewater Characterization Memorandum (DCN CWT00374)
This memorandum discusses both unconventional oil and gas (UOG) and conventional oil and gas (COG) extraction wastewater characterization data, including produced water and drilling wastewater. ERG previously compiled and analyzed produced water and drilling wastewater characterization data sources in support of EPA's 2016 UOG Rulemaking (U.S. EPA, 2016a). For EPA's 2018 Detailed Study of the Centralized Waste Treatment Point Source Category for Facilities Managing Oil and Gas Extraction Wastes (U.S. EPA, 2018), EPA requested that the wastewater characterization be revised to present by author, rather than aggregated. This memorandum discusses the analysis steps that ERG changed or added from the 2016 UOG effort for the purposes of characterizing oil and gas extraction wastewater for the 2018 centralized waste treatment (CWT) study (U.S. EPA, 2018). The development of the UOG Rulemaking wastewater datasets are described in detail in the following memoranda: 
 EPA's UOG Produced Water Volumes and Characterization Data Compilation Memorandum (U.S EPA, 2016b)  -  This memorandum describes methodology for compiling wastewater volumes and characterization data in the UOG Rule Technical Development Document (TDD). 
 EPA's COG Memorandum for the Record (U.S. EPA, 2016c).  -  This memorandum discusses COG extraction wastewater characteristics, as well as management and disposal practices used for COG extraction wastewater. 
 EPA's UOG Drilling Wastewater Memorandum (U.S. EPA, 2016d)  -  This memorandum summarizes information available for UOG drilling wastewater volumes, characteristics, and management.
O&G Extraction Wastewater Characterization Data
	For the CWT Study, ERG developed two Oil and Gas (O&G) Wastewater Characterization databases to compile information about the parameters in UOG and COG extraction wastewater. The O&G Produced Water Characterization database is included in Attachment 1 (DCN CWT00374.A01). The O&G Drilling Wastewater Characterization database is included in Attachment 2 (DCN CWT00374.A02). The development of these two databases is discussed in Section 2.0.

The databases present information about each well (e.g., location), the type of wastewater sampled (e.g., flowback), and the concentrations measured and recorded. Additional information on the sources of UOG produced water characterization data can be found in the UOG Produced Water Volumes and Characterization Data Compilation Memorandum (U.S EPA, 2016b). Additional information on the sources of COG produced water characterization data can be found in the COG Memorandum for the Record (U.S. EPA, 2016c).
In some cases, multiple data sources reference the same original data source; therefore, ERG reviewed each data source to identify and exclude duplicated data. When ERG found duplicated data, ERG selected data from only the original data source. Additionally, ERG referenced the original source of the data. 
Using the data sources, ERG identified and entered concentration data for parameters in produced water and drilling wastewater. These parameters include total dissolved solids (TDS), metals, hardness, and radioactive parameters, among others. 
O&G Wastewater Characterization Databases
This section describes the attachments: O&G Produced Water Characterization database and O&G Drilling Wastewater Characterization database.
O&G Produced Water Characterization Database
ERG used the UOG Produced Water Characterization Database (U.S. EPA, 2016e) and the COG Wastewater Characterization Database (U.S. EPA, 2016f) previously generated to support EPA's 2016 UOG Rulemaking as starting points for the O&G Produced Water Characterization Database (Attachment 1). Table 1 describes the database tables and queries.
      Table 1. O&G Produced Water Characterization Database Functions
                                  Object Type
                                     Name
                                   Function
Table
Pollutant Concentrations_All
Compilation of PW characterization data for both UOG and COG
Table
Pollutant Concentrations_COG
Complete COG PW characterization data from EPA's COG Wastewater Characterization Database (U.S. EPA, 2016f)
Table
Pollutant Concentrations_UOG
Complete UOG PW characterization data from EPA's UOG Produced Water Characterization Database (U.S. EPA, 2016e)
Query
1_Make "All" Table
Creates the Pollutant Concentrations_All table in the database using the UOG PW data
Query
2_Append "All" Table
Adds the COG PW data to the Pollutant Concentrations_All table
Query
3_O&G PW Characterization Data
Compiles the data from the Pollutant Concentrations_All table and calculates the minimum, median, and maximum values for each parameter for each data source
Query
4a_O&G PW Characterization Summary
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for every parameter, regardless of data source
Query
4b_O&G PW Characterization POI Summary
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for each parameter of interest, regardless of data source
Query
5a_O&G PW Characterization Summary by Reference
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for every parameter, grouped by data source
Query
5b_O&G PW Characterization POI Summary by Reference
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for each parameter of interest, grouped by data source
Query
6_Source List
The list of data sources used for O&G PW characterization data
Query
7_Parameter List
The list of parameters of interest developed by EPA
Query
8_O&G PW Characterization POI Summary with Location
Compiles the data from the Pollutant Concentrations_All table and calculates the minimum, median, and maximum values for each parameter for each data source, grouped by geographic location
Query
9a_O&G PW Characterization Data w_Originals
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for every parameter, regardless of data source, with original data sources marked separately from the secondary source citing their data. 
Query
9b_O&G PW Characterization POI Summary by Reference w_Originals
Aggregates the O&G PW data to find the absolute minimum, median, and maximum value for each parameter of interest, grouped by data source, with original data sources marked separately from the secondary source citing their data
PW  -  produced water; POI  -  parameters of interest
The results of Query 9b are used in Tables 5-8 through 5-13 of the Detailed Study of the Centralized Waste Treatment Point Source Category for Facilities Managing Oil and Gas Extraction Wastes (U.S. EPA, 2018).
O&G Drilling Wastewater Characterization Database
ERG used the UOG Drilling Wastewater Volume and Characterization Data Excel File (U.S. EPA, 2016g) as a starting point for the O&G Drilling Wastewater Characterization Database (Attachment 2). Table 2 describes the database tables and queries.
      Table 2. O&G Produced Water Characterization Database Functions
                                  Object Type
                                     Name
                                   Function
Table
Pollutant Concentrations_All
Complete UOG DF characterization data from EPA's UOG Drilling Wastewater Volume and Characterization Data Excel File (U.S. EPA, 2016g)
Query
1a_O&G DF Characterization Summary
Aggregates the O&G DF data to find the absolute minimum, median, and maximum value for every parameter, regardless of data source
Query
1b_O&G DF Characterization POI Summary
Aggregates the O&G DF data to find the absolute minimum, median, and maximum value for each parameter of interest, regardless of data source
Query
2a_O&G DF Characterization Summary by Reference
Aggregates the O&G DF data to find the absolute minimum, median, and maximum value for every parameter, grouped by data source
Query
2b_O&G DF Characterization POI Summary by Reference
Aggregates the O&G DF data to find the absolute minimum, median, and maximum value for each parameter of interest, grouped by data source
Query
3_Source List
The list of data sources used for O&G DF characterization data
Query
4_Parameter List
The list of parameters of interest developed by EPA
DF  -  drilling fluid (wastewater); POI  -  parameters of interest
The results of Query 2b are used in Tables 5-1 through 5-5 of the Detailed Study of the Centralized Waste Treatment Point Source Category for Facilities Managing Oil and Gas Extraction Wastes (U.S. EPA, 2018).
References
 U.S. EPA. 2018. Detailed Study of the Centralized Waste Treatment Point Source Category for Facilities Managing Oil and Gas Extraction Wastes. DCN CWT00311
 U.S. EPA. 2016a. Technical Development Document for Effluent Limitations Guidelines and Standards for Oil and Gas Extraction. DCN CWT00019
 U.S. EPA. 2016b. Unconventional Oil and Gas (UOG) Produced Water Volumes and Characterization Data Compilation. DCN CWT00061
 U.S. EPA. 2016c. Conventional Oil and Gas (COG) Memorandum for the Record. DCN CWT00128
 U.S. EPA. 2016d. Unconventional Oil and Gas Drilling Wastewater Memorandum. DCN CWT00148
 U.S. EPA. 2016e. Unconventional Oil and Gas (UOG) Produced Water Volumes and Characterization Data Compilation - Attachment 13: UOG Wastewater Characterization Database. DCN CWT00061.A13
 U.S. EPA. 2016f. Conventional Oil and Gas (COG) Memorandum for the Record - Attachment 3: COG Wastewater Characterization Database. DCN CWT00128.A03
 U.S. EPA. 2016g. Unconventional Oil and Gas Drilling Wastewater Memorandum Attachment 1: UOG Drilling Wastewater Volume and Characterization Data Excel File. DCN CWT00148.A01
Attachments
 O&G PW Characterization Database (DCN CWT00374.A01)
 O&G DF Characterization Database (DCN CWT00374.A02)
