### MEMORANDUM

TO: Lisa Biddle, EPA

Karen Milam, EPA

FROM: James K. O’Connell, ERG

Jason Sese, ERG Brent Ruminski, ERG Sarah Yates, ERG

DATE: June 6 , 2016

SUBJECT: Conventional Oil and Gas (COG) Memorandum for the Record ( DCN

SGE 01177 )

T his memorandum describes conventional oil and gas (COG) extraction wastewater characteristics, as well as management and disposal practices used for COG extraction

wastewater . This memorandum also describes the data and methods that ERG used to compile

this information. In addition, it includes discussions about data limitations related to the drilling fluids and drilling wastewater from COG extraction operations

.

As explained in the preamble to t he final rule, while the existing oil and gas regulation applies to both COG and UOG extraction (except coalbed methane) 1 , the rule would add pretreatment standards only for facilities engaged in oil and gas extraction from UOG sources

that send their disc harges to POTWs. EPA is reserving standards for conventional oil and gas extraction for possible future rulemaking, if appropriate. This is consistent with EPA’s stated scope th roughout the development of the proposed and final rule. Because COG extraction wastewater was not included in the scope of th is rulemaking, EPA does not have comprehensive

information on the characteristics of COG extraction wastewater and the wastewater management strategies used for COG extraction wa stewater. However, through revi ewing the literature on UOG, EPA obtain ed some information on COG extraction wastewater and this

memorandum is intended to summarize that information.

This memorandum is organized into the following sections:

 Section 1.0 COG extraction wastewater characterization data

 Section 2.0 COG extractio n waste water management practices on a national and

state

- level

 Section 3.0 methodology used by ERG to complete data analyses not described in

othe r supporting memoranda

 Section 4.0 ERG’s quality control procedures

 Section 5.0 lists the references used for these a nalyses

1 In Pennsylvania, CBM well data is categorized as “conventional”. Therefore, data about CBM wells may be included in the PA DEP data cited throughout this memorand um.Memorandum

June 6 , 2016 Page 2

 Section 6.0 provides the attachments to this memorandum

For those figures/tables ERG generated specifically for this memorandum, the underlying

data and a nalysis are contained in:

 Attachment 1

– COG Drilling Wastewater Characterization Data (DCN

SGE011 77

.A01).

 Attachment 2

– COG Produced Water Characterization Data (DCN SGE01177.A02).

 Attachment 3

– COG Wastewater Characterization Database (DCN

SGE01177.A0 3).

 Attachment 4

– USGS Produced Water Database

– COG Data (DCN SGE01177.A04).

1.0 COG E XTRACTION W ASTEWATER C HARACTERIZATION D ATA

The following subsections describe COG drilling wastewater characteristics and COG produced water characteristics and, where available, present relevant data.

1.1 COG Drilling Wastewater Characterization Data

Th is section discuss es drilling wastewater characteristics for COG resources. Drilling

w astewater is the liquid waste stream separated from recovered drilling fluid (mud) and drill cuttings during the drilling process

. S everal categories of constituents are present in most types of drilling waste water (DCN SGE 00733):

 Salt (total dissolved solids);

 Oil and grease;

 Inorganic and organic compounds; and

 Chemical additives used duri ng drilling.

ERG identified minimal available COG drilling wastewater characteristics data (specifically chloride data)

, all of which was specific to COG extraction wells in the Appalachian

Basin. ERG identified COG drilling wastewater characterization data in technical evaluations of the impact of oil and gas wastewater pollutants on POTW unit processes completed in response to Administrative Orders (AOs) 2 issued to a number of POTWs by the Pennsylvania Department of Environmental Protection ( PA DEP ) (D CN SGE00986, DCN SGE00987). The PA DEP data

for COG drilling wastewater included chloride data showing concentrations between 1 6,000 mg/L and 4 0,000 mg/L with a median value of 35,000 mg/L.

1.2 COG Produced Water Ch aracterization Data

This section discuss es p roduced water characteristics for COG resources.

2 PA DEP issued AOs to many POTWs in Pennsylvania that were accepting or suspect ed to begin accepting

wastewater from UOG operations.Memorandum

June 6 , 2016 Page 3

COG produced water typically reflects the characteristics of the C OG formation, including naturally occurring ions. 3 Salinity or salt concentration s
, referred to throughout this

memorandum as TDS, can vary from less than 4,100 to 220,000 mg/L in COG produced water (see Table 1 )

. Figur e 1 shows the ranges of TDS concentrations in COG produced water from

various basins containing COG resources

. T he following ions may contribute to TDS in COG produced water: chloride

, sodium, calcium, cadmium, magnesium, b icarbonate, and sulfate ( DCN SGE01025

, DCN SGE01133)

. Many metals may also be present in COG produced water

. Radioactive decay products in COG produc ed water , when present, are primarily in the form of

radium 226 and radium 228 ( DCN SGE01025)

.

Source: DCN SGE01025

Figur e 1 . TDS Concentrations in COG Produced Water from Various Basins Containing

COG Resources

Table 1 presents typical concentrations of select constituents in COG produced water from ERG’s analysis of the following sources:

 United States Geological Survey’s (USGS) Produced Water Geochemical

Database v. 2. 1 (PROVISIONAL) (DCN SGE00 1260 ) 4

 Pennsylvania Depar tment of Environmental Protection ’s (PA DEP) Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) Study Report (DCN SGE 01028 )

3 S ome COG wells may be hydraulically fractured but ERG has not included a discussion of the differe nt waste

streams that make up produced water if a well is fracture d (i.e. , flowback and long

- term produced water ).

4 This is a comprehensive database covering 37 states from 1885 to 2013.Memorandum

June 6 , 2016 Page 4

 EPA’s Development Document for Interim Final Effluent Limitations Guidelines

(ELGs) and Proposed New Source Performance Standards (NSPS) for the Oil and Gas Extraction Point Source Category (PSC) (DCN SGE00621)

.

The table shows the range s and median concentrations associated with each parameter, the associated number of data points , and the associated number of detects . Constituents are grouped and sorted by pollutant categories (e.g.

, Classical and Conventional) and represent all

basins containing COG resources in the United States. The methodology ERG used to analyze

the se data is described in Section 3.2

.

Table 1 . Concentrations of Constituents in COG Produced Water

Constituent Category Parameter Units Lower and Upper Range a Median Number of

Data Points Number of

Detects

Classical and

Conventional Alkalinity mg/L 13

- 32 18 53 53

Bicarbonate mg/L 59

- 1,700 330 78,441 77,800

Carbonate mg/L 24

- 420 96 10,577 9,182

Chloride mg/L 710

- 150,000 39,000 84,170 84,141

Nitrate mg/L 4.1

- 340 44 3,245 3,222

pH SU 5.6

- 8.3 7.1 63,016 62,926

Phosphate mg/L 0.18

- 6.3 2 39 28

Specific Conductivity mg/L 48,000

- 210,000 120,000 270 258

Sulfate mg/L 20

- 3,200 440 75,690 74,314

Sulfide mg/L 0.41

- 530 12 96 74

TDS mg/L 4,100

- 220,000 59,000 76,595 76,569

TOC mg/L 24

- 770 130 275 275

Metals Aluminum mg/L 0.086

- 32 0.8 830 795

Arsenic mg/L 0.69

- 240 20 39 36

Barium mg/L 2.2

- 200 30 7,482 7,027

Beryllium mg/L 0.00003

- 0.83 0.00013 146 146

Boron mg/L 2.3

- 99 16 1,805 1,747

Cadmium mg/L 0.005

- 8.7 3.1 42 36

Calcium mg/L 40

- 15,000 2,000 84,629 84,549

Chromium mg/L 0.0052

- 5 1 1,773 1,764

Cobalt mg/L 0.001

- 3 0.007 103 103

Copper mg/L 0.024

- 1.2 0.15 904 812

Fluorine mg/L 0.77

- 14 3 205 162

Lead mg/L 1

- 62 3 221 163

Lithium mg/L 1

- 47 6 5,057 4,912

Magnesium mg/L 15

- 2,800 500 83,376 83,046

Manganese mg/L 0.03

- 50 1.1 2,224 2,014

Mercury mg/L 0.0023

- 89 60 24 24

Molybdenum mg/L 0.0013

- 0.056 0.0056 370 370

Nickel mg/L 0.002

- 1.1 0.012 494 493

Potassium mg/L 11

- 2,300 140 17,834 17,783

Selenium mg/L 0.0084

- 380 0.065 54 54

Silver mg/L 0.0035

- 28 1.7 22 22Memorandum

June 6 , 2016 Page 5

Table 1 . Concentrations of Constituents in COG Produced Water

Constituent Category Parameter Units Lower and Upper Range a Median Number of

Data Points Number of

Detects

Sodium mg/L 1,200

- 69,000 20,000 77,992 77,976

Strontium mg/L 10

- 1,300 180 6,041 5,938

Thallium mg/L 45

- 45 45 1 1

Thorium mg/L 0.017

- 1.3 0.048 26 26

Tin mg/L 0.0006

- 0.04 0.003 296 295

Titanium mg/L 0.0011

- 0.06 0.0054 390 390

Vanadium mg/L 0.0004

- 0.021 0.0024 299 299

Zinc mg/L 0.4

- 78 3 723 663

Radioactive

Constituents Gross Alpha pCi/L 690

- 2,500 1,800 4 4

Gross Beta pCi/L 530

- 1,100 910 4 4

Radium 226 pCi/L 130

- 5,100 660 9 9

Radium 228 pCi/L 31

- 690 130 4 4

Source: COG Wastewater Characterization Analysis

- see Attachment 2 (DCN SGE 01177 .A02).

a

– ERG defined lower and upper ranges using the 10th and 90th percentiles of the median values (i.e., the lower range corresponds to the 10th percentile of the median value and the upper range corresponds to the 90th percentile of the median value)

.

TDS provides a measure of dissolved matter including salts (e.g., sodium, chloride), metals, minerals, and organic material ( DCN SGE00046 ). TDS is not a specific chemical, but is defined as the portion of solids that pass through a filter with a nominal pore s ize of 2.0 μm or

less as specified by Standard Method 2540C

- 1997

. 5 As reported in Table 1 , the median concentration of TDS in COG produced water is approximately 59 ,000 mg/L

. Salts are the majority of TDS in COG produced water consisting predominately of sodium and chloride (DCN

S GE01025)

. Figure 2 supports these generalizations , which is based on ERG’s analysis of the

USGS Produced Water Geochemical Database v. 2. 1 (PROVISIONA L) (DCN SGE001260). A s

seen in the figure, on average
, 9 1 percent of the TDS is comprised of sodium and chloride.

5 40 CFR p art 136 lists Standard Method 2540C as an approved test method for TDS.Memorandum

June 6 , 2016 Page 6

Source: COG Wastewater Characterization Analysis

- see Attachment 2 (DCN SGE 01177 .A02)

Figure 2 . Anions and Cations Contributing to TDS Concentrations in COG Produced

Water

2.0 COG E XTRACTION W ASTEW ATER M ANAGEMENT P RACTICES

The following sections discuss management practices for extraction water from COG

resources from national and state

- level sources 6

. COG operators primarily use underground injection, r euse /recycle in subsequent drilling , and transfer to a centralized waste treatment (CWT) facility and/or publicly owned treatment works ( POTW )

.

2.1 National Level Data

Table 2 summarizes information from three national studies :

 1995: Overview of Exploration and Production Waste Volumes and Waste Management Practices in the United States published by ICF Consulting (DCN

S GE01029 )

 2007: Data from a previous report from 2007 included in the U.S. Produced Water Volumes and Management Practices in 2012 report published by John Veil in 2015 (DCN SGE01128)

6 ERG identified state

- level COG extraction wastewater management data for California and Pennsylvania.Memorandum

June 6 , 2016 Page 7

 2012: Current data included in the U.S. Produced Water Volumes and

Management Practices in 2012 report published by John Veil in 2015 ( DCN

SGE01128 )

There is limited nationwide data available in the literature on COG produced water management practices . These studies may have included some UOG extraction wastewater, but based on the study time frames and descriptions of the studied waste streams, ERG assumes that

the numbers primarily represent COG.

Table 2 . Nationwide Management of Onshore Oil and Gas Produced Water (Percent of

Total Produced Water Generated)

Management Practice 1995 2007 2012

Underground Injection : Enhanced Recovery 71 % 5 9 % 46%

Underground Injection : Disposal 21 % 40 % 40 %

Surface Discharge 3% 0.8 % 3%

Reuse/recycle 2% 2 % 11 % Other (e.g., CWT, POTW, evaporation ponds) 3%

Sources: DCN SGE01029; DCN SGE01128

2.2 California

COG produced water in California is primarily managed using Class II disposal and enhanced recovery wells (DCN SGE00966 , DCN SGE01214 , DCN SGE01128 ). Operators also

use other COG produced water management practices, including sending wastewater to POTWs

. Since 1982 , COG operators in California have discharg ed some COG extraction wastewater to

POTWs (DCN SGE01026)

. As of June 2013

, the Sanitation Districts of Los Angeles County ha d permitted 66 CO G “ oil production dischargers ” to discharge to three different POTWs. These 66 dischargers collectively discharge approximately 3.12 million gallons per day ( MGD ) of COG

extraction wastewater to POTWs , with most ( 64 of the 66 dischargers) discharg ing to the Joint

Water Pollution Control Plant in Carson, California. ERG determined that these dischargers represent individual wells that are drilled into COG formations ( DCN SGE01026)

.

2.3 P ennsylvania

ERG’s analysis of Pennsylvania’s management practices for COG extraction wastewater is presented in the Analysis of Pennsylvania Department of Environmental Protection’s (PA DEP) Oil and Gas Waste Reports memorandum (DCN SGE 01182 )

. The results of this analysis

are shown in Figure 3 and Figure 4 below for COG drilling wastewater and COG produced

water , respectively

. In 201 4

, f ive POTWs were accepting COG extraction wastewater from 3,853

different wells in Pennsylvania

. I n Pennsylvani a, from 2004 through 2014 , CWT facilities were

the most commonly used management practice for both COG drilling wastewater and produced

water. Reuse of COG produced water has gradually increased from 2004 to 201 4

.Memorandum

June 6 , 2016 Page 8

Source: DCN SGE 01182

Figure 3 . COG Drilling Wastewater Management Practices in Pennsylvania 7

7 Note: As reported in the PA DEP Waste Reports, “Other” may include the following management practices: land application, road spreading, storage (pendi ng disposal), encapsulation, landfill, or treated onsite prior to NPDES discharge. As previously mentioned, PA DEP includes CBM well data within the “conventional” well data; therefore, the data in Figure 4 may include some CBM data.Memorandum

June 6 , 2016 Page 9

Source: DCN SGE 01182

Figure 4 . COG Produced Water Management Practices in Pennsylvania 8

3.0 S UPPORTING M ETHODOLOGY

The following two sub sections discuss ERG’s methodologies for analyzing COG

extraction wastewater characteristics.

3.1 COG Drilling Wastewater Characterization Analysis

The following explain s how ERG analyzed COG drilling wastewater characterization

data

.

8 Note: As reported in the PA DEP Waste Reports, “Other” may include the following management practices: land application, road spreading, storage (pending disposal), encap sulation, landfill, or treated onsite prior to NPDES discharge. As previously mentioned, PA DEP includes CBM well data within the “conventional” well data; therefore, the data in Figure 4 may include some CBM data.Memorandum

June 6 , 2016 Page 10

3.1.1 COG Drilling Wastewater Characteristics Data Entry and Standardization

ERG entered raw drilling wastewater characterization data into the “DF WW Chara.

Data” tab in Attachment 1 (DCN SGE 01177 .A 0 1). ERG entered the following d ata fields into the spreadsheet : 9

 Resource type (i.e. , COG);

 Formation;

 Category (e.g., Classical and Conventional);

 Measured P arameter;

 Reported M easured/ A verage 10 V alue (i.e., value reported in literature);

 Number of Samples ;

 Number of Detects;

 Units;

 Reference (i.e., DCN number); and

 Notes.

Because naming conventions, terminology, and measurement units differed by data source, ERG standardized each data field to allow for comparison and summary of data across the entire data set . The following list provides detail s on how ERG standardi zed data from

literature in the “DF WW Chara. Data” tab.

 Resource Type

– ERG identified the well API number and/or well names

associated with the raw data found in literature and cross

- referenced one or both fields against to the PA DEP Waste Reports data (DCN SG E 01245 ) to determine the resource type 11

.

 Pollutant Category Assignments

– ERG assigned a p ollutant categor y to each standard parameter name to allow sorting of measured parameters. For example,

chloride was assigned to the “ Classical and Conventional ” cate gory.

 Wastewater Description

– ERG only used literature that specifically reported the wastewater type associated with the characterization data as drilling wastewater. However, different sources may use different terms for drilling wastewater. ERG

included wastewater described as: “pit water

, ” “drilling ,” and “mud ” as drilling

wastewater

.

3.1.2 COG Drilling Wastewater Characteristics Summary Calculations

After consolidating and standardizing all data in the “DF WW Chara . Data” tab, ERG calculated summary statistics that appear in the “DF WW Chara. Summary” tab in Attachment 1 (DCN SGE 01177 .A 0 1). ERG calculated the following for each parameter reported in the “DF

WW Chara. Data” tab:

9 ERG marked data elements that were not included in the literature as “not reported” in Attachment 1.

10 The “reported measured/average” value in the COG drilling wastewater and characterizati on data can represent medians, averages, or other uncharacterized single values.

11 For more information about how the PA DEP Waste Reports identify resource type, see ERG’s Analysis of PA DEP’s Oil and Gas Waste Reports memorandum ( DCN SGE 01182)

.Memorandum

June 6 , 2016 Page 11

 Lower range

– 10 th percentile value of the “ Reported Measured/Average Value ”

column in the “DF WW Chara. Data” tab.

 Upper range

– 90 th percentile value of the “ Reported Measured/Average Value ”
column in the “DF WW Chara. Data” tab.

 Range

– Combines the lower and upper values into a range.

 Medi an value

– Median value of the “ Reported Measured/Average Value ”
column in the “DF WW Chara. Data” tab. 12

 Number of data points

– Sum of the number of data points represented by the data
in the “DF WW Chara. Data” tab.

 Number of detects

– Sum of the number of data points that were not non

- detects or zeros represented by the data in the “DF WW Chara. Data” tab.

ERG defined lower and upper ranges using the 10 th and 90 th percentiles of the reported measured/average values (i.e., the lower range corresponds to the 10 th percentile of the median

value and the upper range corresponds to the 90 th percentile of the median value)

.

3.2 COG Produced Water Characterization Analysis

ERG developed the COG Wastewater Characterization database to collect information about constituents present in COG produced water . The database compiles information about each well (e.g., location), the type of wastewater sampled ( i.e., produced water ), measured constituents, and the range of measured concentrations recorded. The COG Wastewater

Characterization database is included in Attachment 3 (DCN SGE 01177 .A 0 3 ). ERG’s a nalysis and summary of the compiled data are included in Attachment 2 (DCN SGE 01177 .A 0 2).

The s ources of the data in the COG Wastewater Characterization database a nd descriptions of ERG’s analyses of the collected data are described in detail below

.

3.2.1 Data Sources

ERG compiled produced water characterization data from three sources:

 2014 USGS Produced Waters Geochemical Database (USGS database) (SGE01260)

 2015 PA DEP TENORM study report (PA DEP TENORM report) (DCN SGE01028)

 1976 EPA Development Document for Interim Final ELGs and Proposed NSPS

for the Oil and Gas Extraction PSC (1976 EPA Development Document) (DCN SGE00621)

ERG performed a separate analysis to aggregate data from the USGS d atabase by well, as

described in Section 3.2.2 and shown in Attachment 4 (DCN SG E 01177 .A 0 4). After completing the USGS database analysis, ERG standardized the data from the USGS database

, PA DEP

12 One source (SGE00774) provided the average measured result for four samples but did not provide the individual sample results. ERG did not weight these values during the calculation of the median value.Memorandum

June 6 , 2016 Page 12

TENORM report , and 1976 EPA Development Document in the COG Wastewater Characterization database, included in Attachment 3 (DCN SGE 01177 .A03)

.

3.2.2 USGS Database Analysis

The USGS database contains geochemical and other information for produced waters

from both conventional and unconventional oil and gas well types. The database is a compilation of 25 individual databases, publications, or reports. ERG used the USGS database to obtain produced water characterization data to include in the COG Wastewater Characterization Database in Attachment 3 (DCN SGE 01177 .A03).

ERG obtained data from the USGS database v.2. 1 (provisional) (DCN SGE 01260 ) from

the US GS website on December 8, 201 5 and aggregated the data using the steps below for
inclusion in the “ Raw Data 2

- USGS Data ” table in the “COG Wastewater Characterization” database in Attachment 3 (DCN SGE 01177 .A 03). The USGS National Produced Waters

Geochemical Database v. 2. 1 (PROVISIONAL)

– Documentation file (DCN SGE 01260 ) provides additional background about this database and defines all of the fields within the tables in the database. ERG used the following methodology to analyze the USGS data:

S tep 1

– Extract Relevant Data

ERG imported the USGS data into the “USGS Raw Data” table in ERG’s USGS Produced Waters database in Attachment 4 (DCN SGE 01177 .A 0 4) and extracted entries where the well type was “conventional hydrocarbon ”.

Step 2

– Compile Un ique List of Wells and Assign Well IDs

ERG compiled a list of unique wells, based on the following USGS database fields: original database/reference, basin, formation, well name, and well type. ERG assigned each unique well in the extracted dataset from St ep 1 a “Well ID” that was used to aggregate constituent data by well.

Step 3

– “Un

- Crosstab” Data

Because the data were in a crosstab

- type format where the parameter names were stored in the column headings, ERG used a Visual Basic code to pull the result s of each column into a single table with three columns containing the following data: Well ID, Parameter, and Median Value. ERG then removed any negative or null values 13 . Non

- detect values were considered null because no limits of detection were provided.

13 ERG identified some negative values in the data th at referred to numeric codes (e.g., “

- 3=NA, not analyzed, unknown”). ERG also identified non

- coded negative values in the data that referred to actual data values. ERG was unable to find an explanation of these values. These non

- coded negative values accou nted for a small percentage of the full data set; therefore, ERG is comfortable removing them from the analysis since they should not have a significant impact on the results.Memorandum

June 6 , 2016 Page 13

Step 4

– Compile Min, Max, and Sample Data

From the “un

- crosstabbed” data set, ERG queried the reported minimum and maximum

values 14 for each unique Well ID and Parameter and added them to a final table. ERG also extracted the number of total samples, nu mber of detects, and number of coded values (see the “USGS National Produced Waters Geochemical Database v. 2. 1 (PROVISIONAL)

– Documentation” file (DCN SGE 01260 ) for information on coded values). Coded values were then removed from the “un

- crosstabbed” da ta set.

Step 5

– Calculate Medians

On the “un

- crosstabbed” data set, E RG then ran a Visual Basic routin e to calculate median values for each unique combination of Well ID and Parameter. ERG added the calculated median values to the final summary table base d on the data in the “un

crosstabbed” median table. Lastly, the final table was formatted for export into the COG Wastewater Characterization database (DCN SGE 01177 .A03).

Table 3 shows the methodology for the analyses performed in Attachment 4 (DCN

SGE 01177 .A04).

Table 3 . USGS Produced Water Database Methodology

Query(s) Query Description

000 Initialize d [ USGS_Extracted ] table

. 001 A ppended the entries from the entire set of [USGS Raw Data] into [ USGS_Extracted ], where the well

type was “ conventional hydrocarbon ”

. 100 Initialize d [List of Wells] table

. 101 Extracted all unique combinations of IDDB, REFERENCE, BASIN, FORMATION, DFORM,

WELL, and WELLTYPE and appended to [List of Wells]. WellID was auto numbered to create a list of all unique wells.

102 Linked [ USGS_Extracted ] table to [List of Wells] table b y IDDB, REFERENCE, BASIN,

FORMATION, DFORM, WELL, and WELLTYPE

, and updated [ USGS_Extracted ].[WellID] to be equal to [List of Wells].[WellID]. This query assigned WellID values in the [ USGS_Extracted ] table.

103 Updated [ List of Wells].[WellID ] to text fo rmat to allow for linking.

200 Initialize d [ USGS_Extracted_Data_Only_Crosstab ] table

. 201 Appended parameter data from [USGS_Extracted] table to [ USGS_Extracted_Data_Only_Crosstab ]

table

. 300 Initialize d [ USGS_Extracted_Data_Only_Uncrosstab ] table

. 301 Ran “Un

- crosstab” Function, which pulls data from [ USGS_Extracted_Data_Only_Crosstab ] and

outputs to the [ USGS_Extracted_Data_Only_Uncrosstab ] table

. 302 Removed null values from the [ USGS_Extracted_Data_Only_Uncrosstab ] table

. 303 Removed all negative (non

- coded) values from the [ USGS_Extracted_Data_Only_Uncrosstab ] table

. 400 Initialize d [ USGS_Extracted_Data_Only_Uncrosstab_Total Sample Count ] table

. 401 Queried and appended total number of samples for each combination of [WellID] and [Parameter] to

the [ USGS_Extracted_Data_Only_Uncrosstab_Total Sample Count ] table

. 402 Make table to extract data by detects, and each coded value (

- 1 through

- 4)

14 ERG does not use these minimum and maximum values in the subsequent calculatio ns and these values do not appear in Table 1 . See Section 3.2.4 for an ex planation of the values included in Table 1

.Memorandum

June 6 , 2016 Page 14

Table 3 . USGS Produced Water Database Methodology

Query(s) Query Description

403 Updated [ USGS_Extracted_Data_Only_Uncrosstab_Total Sample Count ] table with the results of

query 402.

500 Removed all negative values (all remaining coded values) from the

[ USGS_Extracted_Data_Only_Uncrosstab ] table

. 501 Initialize d [ USGS_Extracted_Data_Only_Uncrosstab_MoreThan2Values ] table

. 502a Queried all combinations of [WellID] and [Parameter] that had more than 2 detected values. (Note:

these queries were used to only calculate medians for situations where more 2 values were reported, which greatly reduces total calculation time).

502b Appended results of query 502a to [ USGS_Extracted_Data_Onl y_Uncrosstab_MoreThan2Values ]

table

. 600 Initialize d [ USGS_Extracted_Data_Only_Median_Summary ] table

. 601 Ran Visual Basic code to calculate medians for values

[ USGS_Extracted_Data_Only_Uncrosstab_MoreThan2Values ] and output to [ USGS_Extracted_Data_Only_ Median_Summary ] table

. 700 (x2) Initialize [USGS Data Summary] and [USGS_Extracted_Data_Min and Max Per Well] tables

701 Appended [ USGS_Extracted_Data_Only_Uncrosstab_Total Sample Count ] table to [USGS Data

Summary] table

702 Appended min and max data from [USGS_Extracted_Data_Only_Uncrosstab] to

[ USGS_Extracted_Data_Min and Max Per Well ] table.

703

- 706 Updated the [USGS Data Summary] table with the min, max, median values, and well information.

707 Updated special case units in [USGS Data Summary] ba sed on [lkpUnits] crosswalk.

708 Updated remaining units in [USGS Data Summary].

709 Updated Number of Detect count to zero in [USGS Data Summary] if is null.

710 Removed min and max values from [USGS Data Summary] if there was only single value present

. 711 Standardize d the format for easy import in to a separate database: Add ed reference to USGS, 2014;

set all WW Descriptions to “Produced”, etc.

3.2.3 COG Wastewater Characterization Database Key Fields and Standardization

Methodology

The COG Wastewater Characterization database (DCN SGE 01177 .A 0 3) combines

information from the USGS database

, the PA DEP TENORM report , and the 1976 EPA Development Document and presents standardized wastewater characterization information on a well basis , including:

 Measure d constituent;

 Constituent category (e.g., metal);

 Wastewater description ( i.e., produced water);

 Sample information (e.g., number of samples, units); and

 Concentration values (e.g., minimum value, median value 15 , maximum value ).

15 The “median” field in the COG Wastewater Characterization database can represent medians, averages, or other

uncharacter ized single values. For the data from the USGS dataset, values in this field represent medians, as calculated by ERG (see Section 3.2.2). ERG did not calculate these values for the PA DEP and EPA 1976 datasets, therefore values are as reported in the data sources (i.e., medians, averages, or other uncharacterized single values).Memorandum

June 6 , 2016 Page 15

ERG extracted the informa tion listed above from each data source, where available. Missing data
elements were marked as “unknown.”

Because naming conventions, terminology, and measured units differed by data source, ERG standardized each data field to allow for comparison and sum mary of data across the entire database. The following sections provide details on how ERG standardized the overall dataset to establish consistency. All of the data, crosswalks, and analyses described below are contained

within the C OG Wastewater Characte rization database (DCN SGE 01177 .A 0 3).

Data Preparation

ERG prepared the USGS data using the methodology described in Section 3.2.2 . ERG did not need to prepare the data from the PA DEP TENORM report or the 1976 EPA Development

Document because these data were in a format that allowed them to be directly entered into the COG Wastewater Characterization database (DCN SGE 01177 .A03).

ER G placed data related to the measured constituent and wastewater description into “raw” data fields, capturing the data as they were reported by the source. Before performing any analyses on the dataset, ERG removed all leading and trailing spaces from the raw data fields.

The queries related to the data preparation are “000a_create Pollutant Concentrations

table shell” through “000g_Update Source Quality Flags” , shown in Table 4

.

Constituent Standardization and Constituent Category Assignments

ERG created a list of all constituents included in the underlying data sources and created a crosswalk “Pollutant Parameter Crosswalk” to standardize constituent names. For example,

“Co” and “Cobalt” were standardized to “Cobalt.”

In a separate “Pollutant Categories Crosswalk,” ERG assigned primary and secondary (optional) c ategories for each standard constituent name to allow for grouping and analysis of certain constituents. For example, aluminum was placed in the “Metals” category. All crosswalks used in the data standardization and/or analyses are contained in the databas e.

The query related to the constituent standardization and category assignments is

“ 001_Update Parameter Names and Categories” , shown in Table 4

.

W astewater Description Standardization

ERG standardized wastewater descriptions provided in each data source using the “WW Description Crosswalk” in the COG Wastewater Characterization database (DCN

SGE 01177 .A03). ERG captured wastewater descriptions as reported in the existing data source and did not reclassify any wastewater descriptions. ERG only standardized names (e.g., “produced formation water” was standardized to “produced water”).

The quer y related to the wastewater description standardization is “ 002_Update WW Descriptions ” , shown in Table 4

.Memorandum

June 6 , 2016 Page 16

Units of Measure Standardization

ERG converted reported constituent concentrations to standardized un its of measure appropriate for each constituent. ERG established a crosswalk, “Unit Definition Crosswalk,” in

the database to list units and conversion factors.

The queries related to the units of measure standardization are “003a_Update Units_Uranium pCi/ L” through “003d_Update Units_pH” , shown in Table 4

.

Minimum, Median 16 , and Maximum Data

For each set of reported constituent concentrations for a part icular constituent from a given source, ERG compared the minimum, median 16 , and maximum values, where available, to ensure regularity in the data. If the reported values did not reflect the correct relative sequence ( i.e., the minimum value is less than the median value which is less than the maximum value ),

ERG reviewed the values to determine if there was error, and if appropriate, corrected the values so that the correct relative sequence was maintained. ERG only considered non

- null values in the analysis. Note that values reported as zero were not considered null values.

In some cases, data sources indicated that certain values were not meas ured because they

did not exceed the limit of detection. Where a source reported a non

- detect value but listed the

associated limit of detection, ERG used the limit of detection as the measured value. Where a source reported a non

- detect value but did not report the associated limit of detection, ERG did not assign a value.

The queries related to the lower range , median, and upper range values standardization

are “101

- Make Table Pollutant Conc FINAL” through “104_Median FINAL” , shown in Table

4

.

Table 4 . Descriptions of Queries in COG Wastewater Characterization Database (DCN

SGE 01177 .A03)

Table/Query Name Table/Query Description

Raw Data 1

– PADEP Raw data from the Pennsylvania Department of Environmental Protection’s (PA DEP) Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) Study Report (DCN SGE01028)

Raw Data 2

– USGS Data Raw data from the United States Geological Survey’s (USGS) Produced Water

Geochemical Database v. 2. 1 (PROVISIONAL) (DCN SGE 01260 )

Raw Data 3

– EPA 1976 Raw data from the EPA’s 1976 Development Document for Interim Final Effluent Limitations Guidelines (ELGs) and Propo sed New Source Performance

Standards (NSPS) for the Oil and Gas Extraction Point Source Category (PSC) (DCN SGE00621) Pollutant Categories

Crosswalk Crosswalk generated by ERG that assigns a pollutant category and (optional) secondary pollutant category to each raw pollutant name from existing literature; also flags pollutants of interest for this analysis

16 The “median” field in the COG Wastewater Characterization database can represent medians, averages, or other uncharacterized single values. For the data from the USGS dataset, val ues in this field represent medians, as calculated by ERG (see Section 3.2.2). ERG did not calculate these values for the PA DEP and EPA 1976 datasets, therefore values are as reported in the data sources (i.e., medians, averages, or other uncharacterized single values).Memorandum

June 6 , 2016 Page 17

Table 4 . Descriptions of Queries in COG Wastewater Characterization Database (DCN

SGE 01177 .A03)

Table/Query Name Table/Query Description

Pollutant Parameter

Crosswalk Crosswalk generated by ERG that matches raw pollutant names reported in existing literature to standardized pollutant names Unit Definition Crosswalk Crosswalk generated by ERG that matches raw units reported in existing

literature to standardized units and includes a conversion factor for the associated concentration values, where relevant WW Description Crosswalk Cros swalk generated by ERG that matches raw wastewater descriptions reported in existing literature to standardized wastewater descriptions
000a_create Pollutant

Concentrations table shell Creates a blank table shell with the fields of interest for this analy sis

000b_Append Raw Data 1

- PADEP Appends the data from the “Raw Data 1

– PADEP” table

000c_Append Raw Data 2

- USGS Data Appends the data from the “Raw Data 2

– USGS Data” table

000d_Append Raw Data 3

- EPA 1976 Appends the data from the “Raw Data 3

– EPA 1976” table

000e_Trim Raw Fields Removes all leading and trailing spaces from the Parameter_Raw

, B asin, WellType_Raw

, WWSampleDescription_Raw , and Units_Raw fields 000f_Delete placeholder row Deletes the placeholder row created in query 000a and any rows that were unintentionally imported and do not contain any characterization data 000g_Update Source Quality Flags Updates the “SourceQualityFlag” field to “A” for all entries in the “Pollutant

Concentrations” table a 001_Update Parameter

Names and Categories Updates the pollutant categories in the “Pollutant Concentrations” table using the “Pollutant Categories Crosswalk” and the “Pollutant Parameter Crosswalk”

tables 002_Update WW Descriptions Updates the wastewater descriptions categories in the “Pollutant Concentrations” table using the “WW Description Crosswalk” table 003a_Update Units_Uranium pCi/L Updates the minimum, median, and maximum values and the units for instances where the pollutant reported was “Uranium” and the units reported were “mg/L”

in the raw data 003b_Update Units_All

Parameters Updates the minimum, median, and maximum values and the units in the “Pollutant Concentrations” table using the “Unit Definition Crosswalk” table 003c_Update Units_Unitless_Specific Gravity Updates the units to “Unitless” in the “Pollutant Concentrations” table for instances where the pollutant reported was “Specific Gravity”

003d_Update Units_pH Updates the units to “SU” in the “Pollutant Concentrations” table for instances where the pollutant repo rted was “pH”

101

- Make Table Pollutant

Conc FINAL Creates the “Pollutant Concentration_FINAL” table by pulling the pollutants of interest for this analysis from the “Pollutant Concentrations” table and excluding records where the “NumberSamples” field i s null
102_Min FINAL Updates the minimum concentration value if the reported values did not reflect the correct relative sequence (minimum value < median value < maximum value)
103_Max FINAL Updates the maximum concentration value if the reported values did not reflect the correct relative sequence (minimum value < median value < maximum value)
104_Median FINAL Updates the median concentration value if the reported values did not reflect the correct relative sequence (minimum value < median value < maxim um value) 201_TDS Contributing Ions

Data Pulls data for TDS, chloride, and sodium by well ID and sample date

. Also included is the count of data points for each well ID . For example, a record that

ha d a measured value for TDS and chloride but not sodium was reported as 2 data points

. 202_COG Produced Water

Characterization Data Pulls data from the “Pollutant Concentration_FINAL” table where the median concentration value is not null for use in calculating summary values for Table 1

Pollutant Concentrati ons Table generated in query “ 000a_create Pollutant Concentrations table shell ” and updated using queries 000b through 003dMemorandum

June 6 , 2016 Page 18

Table 4 . Descriptions of Queries in COG Wastewater Characterization Database (DCN

SGE 01177 .A03)

Table/Query Name Table/Query Description

Pollutant Concentrations_FINAL Table generated in query “ 101

- Make Table Pollutant Conc FINAL ” and updated in queries 102 through 104

a

– S ee Section 4.0 for definitions of source flags

3.2.4 Data Summary Analysis

Once all of the data was compiled into a single standardized table in the Attachment 3 database, ERG exported the data to the Microsoft Excel spreadsheet contained in Attachment 2

. In Attachment 2 (DCN SGE 01177 .A 0 2), ERG generate d summary tables and figures for this

memorandum . The Table of Contents (TOC) in Attachment 2 indicates the specific tabs with

data and calculations for each C OG figure and table.

The “ Summary COG PW Char Data ” tab in Attachment 2 contains the standardized data generated by the database queries in Attachment 3. Using the raw data in the “ COG PW Ch ar Data ” tab, ERG generated Table 1 in Section 1.2 by tabulating the lower range, median, and

upper range of concentration along with the number of data points and detects 17 for each applicable constituent

. 18 ERG defined lower and upper ranges using the 10 th and 90 th percentiles

of the median values for each well ID (i.e., the lower range corresponds to the 10 th percentile of

the median value and the upper range corresponds to the 90 th percentile of the median value)

.

The “ TDS Contrib Data ” tab in Attachment 2 contains the standardized TDS, ch loride, and sodium data generated by the database query 201 in Attachment 3. These concentration s for TDS, chloride, and sodium are aggregated for each well ID and sample date. Only well IDs with

measured values for all three constituents are included. On the “ Summary TDS Contrib Data ” tab, ERG calculated the average concentration for TDS, chloride, and sodium. Next , to estimate the typical concentration of “Other Dissolved Constituents” , ERG subtracted the sum of average chloride and average sodium concent rations from the average TDS concentration . E RG generated Figure 2 in Section 1.2 using these results.

4.0 Q UALITY C ONTROL P ROCEDURES

All of the analyses presented in this memorandum adhered to the Environmental Engineering Support for Clean Water Regulations Programmatic Quality Assurance Project Plan (PQAPP) (DCN SGE00957) and the Unconventional Oil and Gas (UOG) Supplemental Quality

A ssurance Project Plan (SQAPP) (DCN SGE00958), including collecting, evaluating, and analyzing data and information related to COG resources

.

Specifically, ERG used the procedures described in Section 4 of the PQAPP to gather and manage existing data in sup port of the UOG proposed rulemaking. ERG staff entered reference

information for relevant sources into the UOG Literature Review database. The ERG index keeper reviewed all reference information, assigned each reference a Document Control Number

17 Number of data points was based on the total number of samples taken; number of detects was based on the number of data points with valid measurements.

18 ERG excluded five pH values that were greater than 14 SU because these were determi ned to be outliers.Memorandum

June 6 , 2016 Page 19

(DCN), imp orted the reference information into the UOG Project File Index database, and saved referenced files in the Electronic Project File folder.

ERG also used the procedures described in Section 3 of the SQAPP when collecting existing data for use in the UOG pr oposed rulemaking. ERG used a combination of sources, including reports, papers, and online databases from state regulatory agencies such as departments of environmental protection and oil and gas commissions. As shown in Table 5 in this memorandum, ERG assigned a source flag (A, B, C or D) to all references used in these analyses which are defined below.

 Source Flag A

– Journal articles and documents p repared by or for a government agency (e.g., site visit reports, industry meeting notes);

 Source Flag B

– Documents prepared by a verified 19 source that include citation information (e.g., operator reports, vendor documents, university publications);

 Sour ce Flag C

– Documents prepared by a verified source that do not include citation information (e.g., operator reports, vendor documents, conference presentations); and

 Source Flag D

– Documents prepared by a source that could not be verified and

that do not include citation information.

EPA and ERG followed PQAPP procedures for spreadsheets (Section 7.0) and databases (Section 8.0) to generate, evaluate, and analyze data using a sprea dsheet and databases . ERG conducted the following QA checks during the analyses:

 ERG created the databases and spreadsheet s provided in Attachment s 1

- 4 (DCN

SGE 01177 .A 0 1

- 0 4 ) to track useful data and to document analyses.

 ERG performed a 20 percent check of all data entry.

 ERG performed a 100 percent check of all data analyses and calculations, and

documented these checks in internal versions of the spreadsheet s and databases

.

 An ERG senior staff member familiar with ELGs and the rulemaking reviewed

the resu lts from each analysis in the spreadsheet s and database s.

5.0 R EFERENCES

Table 5 lists the references that ERG used for the analyses discussed in this

mem orandum. ERG assigned source flags to each of the sources referenced in this memorandum (see Section 4.0 for definitions of source flags).

Table 5

. References Used for This Memorandum

DCN Source Citation Source Flag a

SGE00046 Abdalla, Charles W. et. al. 2011. Marcellus Shale Wastewater Issues in PA

Current & Emerging Treatment & Disposal Technologies. Penn State Cooperative B

19 ERG considered sources as “verified” if we were able to find information about the author outside of the reference document. ERG primarily verified information by looking for company/organization websites that confirmed the

author’s affiliation with the oil and gas industry.Memorandum

June 6 , 2016 Page 20

Table 5

. References Used for This Memorandum

DCN Source Citation Source Flag a

SGE00621 U.S. EPA. 1976. Development Document for Interim Final Effluent Limitations

Guidelines and Proposed New Source Performance Standards for the Oil and Gas Extraction Point Source Category. (September). A

SGE00625 U.S. EPA. 2015. Site Visit Report: Southwestern Energy Fayetteville Shale Gas

Operations. Sanitized. A

SGE00733 National Petroleum Council (NPC). 2011. Waste Management Paper #2

- 24.

Technology Subgroup of the Operations & Environment Task Group. (September 15). B

SGE00774 Ziemkiewicz, P. 2013. Water Quality Literature Review and Field Monitoring

of Active Shale Gas Wells. (February 15). A

SGE00957 ERG. 2013. Environmental Engineering Support for Clean Water Regulations

Programmatic Quality Assurance Project Plan (PQAPP). A

SGE00958 ERG. 2014. Unconventional Oil and Gas (UOG) Supplemental Quality

Assurance Project Plan (SQAPP). A

SGE00966 CCST. 2014. Advanced Well Stimulation Technologies in California: An

Independent Review of Scientific and Technical Information. A

SGE00984 U.S. Energy Information Administration. 2014. Glossary. Retrieved from

http://www.eia.gov/tools/glossary A

SGE00986 Rost, J. 2010. Municipal Authority of the City of McKeesport : Analysis of Gas

Well Wastewaters as Required Under the PA DEP AO Dat ed October 23, 2008

. File 1. A

SGE00987 Rost, J. 2010. Municipal Authority of the City of McKeesport : Analysis of Gas

Well Wastewaters as Required Under the PA DEP AO Dated October 23, 2008.

File 2. A

SGE01025 U.S. Department of the Interior Bureau of Reclamation. 2011. Oil and Gas

Produced Water Management and Beneficial Use in the Western United States. A

SGE01026 Sanitation Districts of Los Angeles County. 2013. Memorandum: Districts'

Pretreatment Program for Oil Production. (June 14). A

SGE01028 PA DEP. 2015. Technologically Enhanced Naturally Occurring Radioactive

Materials (TENORM) Study Report. A

SGE01029 ICF Consulting. 2000. Overview of Exploration and Production Waste Volumes

and Waste Management Practices in the United States. B

SGE01128 Veil, J. 2015. US Produced Water Volumes & Management Practices in 2012.

Veil Environmental, LLC. Prepared for Ground Water Protection Council (GWPC). B

SGE01133 Benko, K.L. and Drewes, J.E. 2008. Produced Water in the Western US:

Geographical Distribution, Occurrence, and Composition. US Bureau of

Reclamation. A

SGE01182 ERG. 2016. Analysis of Pennsylvania Department of Environmental

Protection’s Oil and Gas Waste Reports. A

SGE01214 California Council on Science and Technology. 2015. An Inde pendent

Scientific Assessment of Well Stimulation in California. B

SGE01245 ERG. 2015. Pennsylvania Department of Environmental Protection’s (PA DEP)

Statewide Oil and Gas Waste Reports. (November) A

SGE0 1260 U.S. Geological Survey (USGS). 2014. National Produced Waters Geochemical

Database v2. 1 (Provisional). AMemorandum

June 6 , 2016 Page 21

a

— Source Flag A

— J ournal articles and documents prepared by or for a government agency (e.g., site visit reports, industry meeting notes). Source Flag B

— Documents prepared by a verified source that include citation information (e.g., operator reports, vendor documents, university publications). Source Flag C

— Documents prepared by a verified source that do not include citation information (e.g., operator reports, vendor documents, conference pres entations). Source Flag D

— Documents prepared by a source that could not be verified and that do not include citation

information.

6.0 A TTACHMENTSA TTACHMENT 1

– COG D RILLING W ASTEWATER C HARACTERIZATION D ATA (DCN

SGE 01177 .A 0 1 )A TTACHMENT 2

– COG P RODUCED W ATER C HARACTERIZATION D ATA (DCN

SGE 01177 .A 0 2 )A TTACHMENT 3

– COG W ASTEWATER C HARACTERIZATION D ATABASE (DCN

SGE 01177 .A 0 3)A TTACHMENT 4

– USGS P RODUCED W ATER D ATABASE

– COG D ATA (DCN SG E 01177 .A 0 4)