### MEMORANDUM

TO: Lisa Biddle, EPA

FROM: Brent Ruminski, ERG

James K. O’Connell, ERG
Jason Sese, ERG

DATE: March 31 , 2015

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

SGE0 1016 )

T his memorandum discusses 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, t his memorandum includes discussions about data limitations

related to the drilling fluids and drilling wastewater from COG extraction operations

.

As explained in the preamble to the proposed rule, while the existing oil and gas regulation applies to both COG and UOG extraction (except coalbed methane) 1 , the proposed rule would add pretreatment standards only for facilities engaged in oil and gas extraction from UOG sources that send their discharges to PO TWs. EPA proposes to reserve 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 rule. Because

COG extraction wastewater was not explicitly included in the scope of the rulemaking, EPA

does not have comprehensive information on the characteristics of COG extraction wastewater

and the wastewater management strategies used for COG extraction wastewater. However, through reviewing the literature on UOG, EPA did obtain 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 discusses COG extraction wastewater characterization data

.

 Section 2.0 discusses C OG produced water management practices on a national

and state

- level

.

 Section 3.0 d escribes the methodology used by ERG to complete data analyses

n ot described in other supporting memoranda

.

 Section 4.0 describes ERG’s quality control procedures.

 Section 5.0 lists the references used for these analyses.

 Section 6.0 provides the attachments to this memorandum.

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

March 3 1 , 2015 Page 2

This memorandum will refer to the following terms:

 Conventional oil and gas (COG) resources

- Crude oil and natural gas that is produced by a well drilled into a geologic formation in which the reservoir and fluid characteristics permit the oil and natural gas to readily flow to the wellbore (DCN SGE00984)

.

 Unconventional oil and gas (UOG) resources 2

- crude oil and natural gas 3
produced by a well drilled 4 into a low poros ity, low permeability formation

.

 C OG extraction wastewater

- sources of wastewater pollutants associated with production, field exploration, drilling, well completion, or well treatment for conventional oil and gas extraction

. 5 C OG extraction wastewater includes produced water, drilling wast ewater, and produced sand 6

.

 Drilling wastewater

– the liquid waste stream separated from recovered drilling fluid (mud) and drill cuttings during the drilling process. 7

 P roduced water

– the water (brine) brought up from the hydrocarbon

- bearing

strata during the extraction of oil and gas. This can include formation water, injection water, and any chemicals added downhole or during the oil/water separation process

.

1.0 COG E XTRACTION W ASTEWATER C HARACTERIZATION D ATA

The following subsections describe COG d rilling 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 ast ewater is the liquid waste stream separated from recovered drilling fluid (mud) and drill cuttings during the drilling process

. N early all of the initial drilling fluid is recovered during the drilling process as drilling wastewater (DCN SGE 00625). 8

S everal categories of constituents are present in most types of drilling waste water (DCN

SGE 00733):

 Salt (total dissolved solids);

2 UOG resource types are categorized into shale and tight formations.

3 Natural gas can include “natural gas liquids,” components that are liquid at am bient temperature and pressure.

4 Oil and gas wells may be drilled using horizontal, vertical, or directional well trajectories. Literature sometimes refers to well trajectory as “drill type”.

5 Stormwater is not considered a source of COG extraction waste water. In general, no NPDES permit is required for discharges of stormwater from any field activities or operations associated with oil and gas production, except as specified in 40 C.F.R. 122.26(c)(1)(iii) for discharges of a reportable quantity or that c ontribute to a violation of a water quality standard . States may impose additional requirements for management of drilling site stormwater.

6 Produced sand is not discussed in this memorandum.

7 Drilling fluid (mud) is the circulating fluid used in the ro tary drilling of wells to clean and condition the hole and to counterbalance formation pressure. Drill cuttings are the particles generated by drilling into subsurface geologic formations and carried out from the wellbore with the drilling fluid.

8 Some of the drilling fluid volume may be lost in the cuttings, to evaporation, and/or to seepage into the formation but one operator reported these losses to be minimal.Memorandum

March 3 1 , 2015 Page 3

 Oil and grease;

 Inorganic and organic compounds; and

 Chemical additives used during drilling.

ERG identified minimal available COG drilling wastewater characteristics 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

wastewate r pollutants on POTW unit processes completed in response to Administrative Orders (AOs) 9 issued to a number of POTWs by PA DEP (DCN SGE00986, DCN SGE00987). ERG identified chloride concentration data reporting concentrations between 10,000 mg/L and 150,00 0 mg/L with a median value of 35,000 mg/L.

1.2 COG Produced Water Ch aracterization Data

This section discuss es produced water characteristics for COG resources.

COG produced water typically reflects the characteristics of the C OG formation, including naturally occurring ions. 10 Salinity or salt concentration s
, referred to throughout this

memorandum as TDS, can vary from <5

– 500,000 mg/L in COG produced water (see Table 3)

. Figure 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: sodium, calcium, cadmium, magnesium, chloride, b icarbonate, and sulfate. Barium, potassium,

and strontium 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)

.

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

wastewater from UOG operations.

10 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 produ ced water ).Memorandum

March 3 1 , 2015 Page 4

Source: DCN SGE010 25

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

COG Resources

Table 1 presents typical concentrations of select constituents from ERG’s analysis of the United States Geological Survey’s (USGS) Produced Water Geochemical Database v. 2.0 (PROVISIONAL) (DCN SGE00956) 11

, the Pennsylvania Department of Environmental

Protection ’s (PA DEP) Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) Study Report (DCN SGE 01028 ) , and EPA’s Development Document for Interim

Final Effluent Limitations Guidelines (ELGs) and Proposed New Source Performance Standards (NSPS) for the Oil and Gas Extraction Poin t 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 catego ries (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 Range a Median Number of

Data Points Number of

Detects

Classical and

Conventional Alkalinity mg/L 1.4

– 46 18 53 53

Bicarbonate mg/L 0.11

- 200,000 330 75,567 74,977

Carbonate mg/L 1

- 170,000 96 10,218 8,823

Chloride mg/L 0.65

- 1,100,000 39,000 80,808 80,779

Nitrate mg/L 0.1

- 280,000 44 3,234 3,212

11 This is a comprehensive database covering 36 states from 1885 to 2012.Memorandum

March 3 1 , 2015 Page 5

Table 1 . Concentrations of Constituents in COG Produced Water

Constituent Category Parameter Units Range a Median Number of

Data Points Number of

Detects

pH SU 0.051

– 14 7.1 60,3 19 60,2 34

Phosphate mg/L 0.1

– 20 2 39 28

Specific Conductivity mg/L 11,000

- 220,000 130,000 462 450

Sulfate mg/L 0.2

- 92,000 450 73,004 71,758

Sulfide mg/L 0.15

- 72,000 12 97 75

TDS mg/L 3.4

- 530,000 61,000 75, 103 75,077

TOC mg/L 6

- 2,400 130 275 275

Metals Aluminum mg/L 0.00018

- 2,200 0.8 817 782

Arsenic mg/L 0.002

- 23,000 1 0 2 9 2 6

Barium mg/L 0.002

- 3,900 30 7,3 46 6,8 91

Beryllium mg/L 0.00002

- 5 0.0001 133 133

Boron mg/L 0.01

- 650 15 1,774 1,716

Cadmium mg/L 0.0 05

- 34,000 4

, 7 00 84 7 8

Calcium mg/L 0.008

- 110,000 2,000 81,353 81,273

Chromium mg/L 0.0003

- 370 1 1,75 9 1,7 50

Cobalt mg/L 0.0003

- 3 0.0055 92 92

Copper mg/L 0.0001

– 150 0.15 891 799

Fluorine mg/L 0.05

- 22,000 1.6 174 131

Lead mg/L 0.001

- 8,200 3 2 10 15 2

Lithium mg/L 0.08

- 1,700 6 4,921 4,776

Magnesium mg/L 0.06

- 47,000 510 80,146 79,818

Manganese mg/L 0.0007

- 4,100 1.1 2,308 2,097

Mercury mg/L 0.0005

– 100 60 24 24

Molybdenum mg/L 0.00028

- 1,500 0.005 351 351

Nickel mg/L 0.0003

– 70 0.012 482 481

Potassium mg/L 0.2

- 54,000 140 17,167 17,116

Selenium mg/L 0.0008

- 0.8 0.021 23 23

Silver mg/L 0.002

– 3 1 12 12

Sodium mg/L 0.23

- 150,000 20,000 74,785 74,769

Strontium mg/L 0.03

- 13,000 180 5,920 5,817

Thallium mg/L NA 45 1 1

Thorium mg/L 0.008

- 20 0.02 16 16

Tin mg/L 0.0001

- 1,600 0.003 286 285

Titanium mg/L 0.0002

- 30 0.0054 390 390

Vanadium mg/L 0.00001

- 300 0.0024 299 299

Zinc mg/L 0.0002

- 580 3 711 651

Radioactive

Constituents Gross Alpha pCi/L 470

- 2,600 1,800 4 4

Gross Beta pCi/L 400

- 1,100 910 4 4

Radium 226 pCi/L 81

- 5,300 660 9 9

Radium 228 pCi/L 26

- 900 130 4 4Memorandum

March 3 1 , 2015 Page 6

Table 1 . Concentrations of Constituents in COG Produced Water

Constituent Category Parameter Units Range a Median Number of

Data Points Number of

Detects

NA

– range is not applicable because min imum = median = maximum. Source: COG Wastewater Characterization Analysis

- see Attachment 2 (DCN SGE01016.A02).

a

– ERG did not use reported minimum and maximum values for the summary tables; instead, ranges were defined using the lowest and highest median values (i.e., the minimum value corresponds to the minimum median value and the maximum value corresponds to the h ighest median value) . See Section 3.2.4 for more

details about these calculations.

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 size of 2.0 μm or less ( Standard Method 2540C

- 1997, ASTM D5907

- 03, and USGS I

- 1750

- 85 ). As reported in

Table 1 , the median concentration of TDS in COG produced water is approximately 60,000 mg/L

. Salts are the majority of TDS in COG produced water and sodium chloride contributes to the majorit y of the TDS in COG produced water (DCN SGE01025)

. Figure 2 supports these generalizations. As seen in the figure, on average
, 98 percent of the TDS is comprised of sodium

and chloride.

Source: COG Wastewater Characterization Analysis

- see Attachm ent 2 (DCN SGE01016.A02)

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

WaterMemorandum

March 3 1 , 2015 Page 7

2.0 COG E XTRACTION W ASTEW ATER M ANAGEMENT P RACTICES

The following sections discuss management practices for produced water from COG

resources from national and state

- level sources 12

. For management of drilling wastewater, 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 two national studies (DCN SGE01029; DCN SGE00182) . The first study is from 1995, and the most recent report represents 2007 data . 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 it was negligible

and that the numbers can be assumed to primarily represent COG.

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

Prod uce d Water Generated)

Management Practices 1995 2007

Underground Injection : Enhanced Recovery 71 % 55 %

Underground Injection : Disposal 21 % 39 %

Surface Discharge 3 % 4 %

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

Sources: DCN SGE00182 ; DCN SGE01029

2.2 California

COG produced water in California is primarily managed using Class II disposal and enhanced recovery wells (DCN SGE00966 , DCN SGE00182 ). Operators may use other COG produced water management practices, including sending wa stewater 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 have permitted 66 COG “ 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

. O f the 66 dischargers, 64 discharge to the Joint Water

Pollution Control Plant in Car son, California. ERG determined that these 66 dischargers represent individual wells that are drilled into COG formations ( DCN SGE01026)

.

2.3 P ennsylvania

ERG’s analysis of management practices for COG extraction wastewater is presented in

the Analysis of Pen nsylvania Department of Environmental Protection’s (PA DEP) Oil and Gas Waste Reports memorandum (DCN SGE00739 )

. The results of this analysis are shown in Figure

3 and Figure 4 below for COG drilling wastewater and COG produced water , respectively

. As of

12 ERG identified state

- level COG produced water management data for California and Pennsylvania.Memorandum

March 3 1 , 2015 Page 8

2013, four POTWs were accepting COG extraction wastewater from 2,710 different wells in Pennsylvania

. I n Pennsylvania, for the time period shown in Figure 3 and Figure 4 (i.e., 2004 through 2013) , CWT facilities were the most commonly used management practice for both

COG drilling wastewater and COG produced water. Reuse of COG produced water has gradually

in creased from 2004 to 2013.Memorandum

March 3 1 , 2015 Page 9

Note: As reported in the PA DEP Waste Reports

, “Other” may include the following management practices: land application, road spreading, storage (pending disposal) , or treated onsite prior to NPDES discharge. As previously me ntioned, PA DEP includes CBM well data within the “conventional” well data;

t herefore, the data in Figure 3 may include some CBM data

.

Source: DCN SGE00739

Figure 3

. COG Drilling Wastewater Management Practices in PennsylvaniaMemorandum

March 3 1 , 2015 Page 10

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

.

Source: DCN SGE00739

Figure 4

. COG Produced Water Management Practices in Pennsylvania

3.0 S UPPORTING M ETHODOLOGY

The following two sections dis cuss ERG’s methodologies for analyzing drilling

wastewater and produced water characteristics for COG resources.

3.1 COG Drilling Wastewater Characterization Analysis

The following two subsections explain how ERG analyzed COG drilling wastewater

characterization data

.Memorandum

March 3 1 , 2015 Page 11

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 SGE0 1016 .A 0 1). ERG entered the following d ata fiel ds into the spreadsheet : 13

 Resource type (i.e., COG);

 Formation;

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

 Measured P arameter;

 Reported M easured/ A verage 14 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 measured 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 aga inst to the PA DEP Waste Reports data (DCN SGE00188) to determine the resource type 15

.

 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 assi gned to the “ Classical and Conventional ” category.

 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 differe nt 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 C hara. Data” tab, ERG calculated summary statistics that appear in the “DF WW Chara. Summary” tab in Attachment 1 (DCN SGE0 1016 .A 0 1). ERG calculated the following for each parameter reported in the “DF

WW Chara. Data” tab:

13 ERG marked data elements that were not included in the literature as “no t reported” in Attachment 1.

14 The “average” value in the COG drilling wastewater and characterization data can represent medians, averages, or other uncharacterized single values.

15 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 SGE00739 )

.Memorandum

March 3 1 , 2015 Page 12

 Min imum value

– Smallest value in the “ Reported Measured/Average Value ”

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

 Max imum value

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

 Range

– Combines the minimum and maximum values into a range.

 Median value

– Median value in the “ Reported Measured/Average Value ” column

in the “DF WW Chara. Data” tab. 16

 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.

3.2 COG Produced Water Characterization Database

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 Wastew ater
Characterization database is included in Attachment 3 (DCN SGE01016.A 0 3 ). ERG’s a nalysis and summary of the compiled data are included in Attachment 2 (DCN SGE01016.A 0 2).

The s ources of the data in the COG Wastewater Characterization database and

des criptions of ERG’s analyses of the collected data are described in detail in the following

sections of this memorandum.

3.2.1 Data Sources

ERG compiled produced water characterization data from three sources: t he 2014 USGS

Produced Waters Geochemical Database (U SGS database)

, the 2015 PA DEP TENORM study

report (PA DEP TENORM report) , and the 1976 EPA Development Document for Interim Final ELGs and Proposed NSPS for the Oil and Gas Extraction PSC (1976 EPA Development Document) . 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 SGE01016.A 0 4). After completing the USGS database analysis, ERG standardized the data from the USGS database

, PA DEP TENORM report , and 1976 EPA Development Document in the COG Wastewater Characterization database, included in Attachment 3 (DCN SGE01016.A0 3).

3.2.2 USGS Database Analysis

The USGS database contains geochemical and other information for produced waters from both conventional and unconventional well types. The database is a compilation of 25 individual databases, publications, or reports. ERG used t he USGS database to obtain produced

water characterization data to include in the COG Wastewater Characterization Database in Attachment 3 (DCN SGE01016.A03).

16 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 duri ng the calculation of the median value.Memorandum

March 3 1 , 2015 Page 13

ERG obtained data from the USGS database v.2.0 (provisional) (DCN SGE00956) from

the USGS website on August 8, 2014 and aggregated the data for inclusion in the “ Raw Data 2

- USGS Data ” table in the “COG Wastewater Characterization” database in Attachment 3 (DCN

SGE01016.A 03). The USGS National Produced Waters Geochemical Database v. 2.0 (PROVISIONAL)

– Documentation file (DCN SGE00956) 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:

Step 1

– Extract Relevant Data

ERG importe d the USGS data into the “USGS Raw Data” table in ERG’s USGS Produced Waters database in Attachment 4 (DCN SGE01016.A 0 4) and extracted entries where the well type was “conventional hydrocarbon ”.

Step 2

– Compile Unique List of Wells and Assign Well IDs

ER G 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 Step 1 a “Well ID” that was used to

aggrega te 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 results 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 17 . Non

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

Step 4

– Compile Min, Max, and Sample D ata

From the “un

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

values 18 for each unique Well ID and Parameter and added them to a final table. ERG also extracted the number of total samples, number of detects, and number of coded

valu es (see the “USGS National Produced Waters Geochemical Database v. 2.0 (PROVISIONAL)

– Documentation” file (DCN SGE00956) for information on coded values). Coded values were then removed from the “un

- crosstabbed” data 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

17 ERG identified some negative values in the data that 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 accounted 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 t he results.

18 ERG does not use these minimum and maximum values in the subsequent calculations and these values do not appear in Table 1 . See Section 3.2.4 for an explanation of the values included in Table 1

.Memorandum

March 3 1 , 2015 Page 14

calculated median values to the final summary table based on the data in the “un

crosstabbed” med ian table. Lastly, the final table was formatted for export into the COG Wastewater Characterization database (DCN SGE01016.A03).

Table 3 shows the methodology for t he analyses performed in Attachment 4 (DCN SGE01016.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 format 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 negati ve (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)

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_Only_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.Memorandum

March 3 1 , 2015 Page 15

Table 3 . USGS Produced Water Database Methodology

Query(s) Query Description

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] based 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 SGE01016.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, including:

 Measured 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 19 , maximum value).

ERG extracted the information listed above from each data source, where available. Missing data

elements were marked as “unknown.”

Because naming conventions, terminology, and measu red units differed by data source, ERG standardized each data field to allow for comparison and summary 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 Characterization database (DCN SGE01016.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 th at allowed them to be directly entered into the COG Wastewater Characterization database (DCN SGE01016.A03).

19 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, values in th is 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 va lues).Memorandum

March 3 1 , 2015 Page 16

ERG 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 Sour ce Quality Flags” , shown in Table 4

.

Constituent Standardization and Constituent Category Assignments

ERG created a list of all constituents included in the underlyi ng 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 (opt ional) categories 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 database.

The query related to the constituent standardization and category assignments is

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

.

Wastewater Description Standardization

ERG standardized wastewater descriptions provided in each data source using the “WW Description Crosswalk” in the COG Wastewater Characterization database (DCN SGE01016.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 st andardization is “ 002_Update WW Descriptions ” , shown in Table 4

.

Units of Measure Standardization

ERG converted reported constituent concentrations to standardized units 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

Un its_Uranium pCi/L” through “003d_Update Units_pH” , shown in Table 4

.Memorandum

March 3 1 , 2015 Page 17

Minimum, Median 20 , and Maximum Data

For each set of reported constituent concentra tions for a particular constituent from a given source, ERG compared the minimum, median 20 , and maximum values, where available, to ensure regul arity in the data. If the reported values did not reflect the correct relative sequence (minimum value < median value < maximum value), ERG reviewed the values to determine the source of error, and if appropriate, corrected the values so that the correct r elative 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 measured 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 minimum, median, and maximum values standardization are

“101

- Make Table Pollu tant Conc FINAL” through “104_Median FINAL” , shown in Table 4

.

Table 4 . Descriptions of Queries in COG Wastewater Characterization Database (DCN SGE01016.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. 2.0 (PROVISIONAL) (DCN SGE00956)

Raw Data 3

– EPA 1976 Raw data from the EPA’s 1976 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) 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

Pollutant Parameter

Crosswalk Crosswalk generated by ERG that matches raw po llutant 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 associ ated concentration values, where relevant WW Description Crosswalk Crosswalk 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 analysis

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” tabl e

20 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, values in this field represent medians, as calculated by ERG (see Secti on 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

March 3 1 , 2015 Page 18

Table 4 . Descriptions of Queries in COG Wastewater Characterization Database (DCN SGE01016.A03)

Table/Query Name Table/Query Description 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” tabl es 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 “U nit 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 reported 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 “P ollutant Concentrations” table and excluding records where the “NumberSamples” field is 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 < maximum value) 201_TDS Contributing Ions

Data Pulls data for TDS, chloride, and sodium where the median concentration value is

not null
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 Concentrations Table generated in que ry “ 000a_create Pollutant Concentrations table shell ” and updated using queries 000b through 003d

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 ERG standardized all of the data and compiled it into a single summary table in the database, ERG exported data for the selected constituents from the database to Excel to generate summary tables and figures for this memorandum . Attachment 2 (DCN SGE01016.A 0 2) includes the Excel file with the exported data and all of the analyses that ER G conducted to generate 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.Memorandum

March 3 1 , 2015 Page 19

ERG did not use reported minimum and maximum values for the summary tables; instead, ranges were defined using the lowest and highest median values (i.e., the minimum value corresponds to the minimum median value and the maximum value corresponds to the highest median value). 21

E RG generated Table 1 in Section 1.2 by ta bulating the minimum of the median data field, median of the median data field, maximum of the median data field, number of data points,

and number of detects 22 for each applicable constituent 23

.

ERG generated Figure 2 in Section 1.2 by first tabulating the median concentration for the primary ionic contributor s to TDS ( i.e ., chloride, sodium ) 24 (see the “TDS Contrib Ions Data ”

tab in Attachment 2, DCN SGE01016 .A 0 2 ). ERG listed the primary ionic contributors as individual constituents, while minor contributors were combined into the “Other Dissol ved Constituents” category for the purpose of Figure 2

.

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 (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. Only documents prepared by a government agency or for a government agency were used in this analysis.

 Source Flag A

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

21 As discussed previously, the “median” values may r epresent medians, averages, or other uncharacterized single

values.

22 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.

23 ERG excluded five pH values tha t were greater than 14 SU because these were determined to be outliers.

24 ERG determined that chloride and sodium made up 98% of the TDS and therefore, included these two constituents as the primary ionic contributors in Figure 2

.Memorandum

March 3 1 , 2015 Page 20

 Source Flag B

– Documents prepared by a verified 25 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., opera tor 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 spreadsheet 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

SGE0 1016 .A 0 1

- 0 4 ) to t rack 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 E RG senior staff member familiar with ELGs and the UOG proposed rulemaking reviewed the results 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 memorandum. 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.; Drohan, Joy R.; Blunk, Kristen S.; Edson, Jessie. 2011.

Marcellus Shale Wastewater Issues in Pennsylvania

- Current and Emerging Treatment and Disposal Technologies. Penn State Cooperative Extension, College of Agricultural Sciences. B

SGE00182 Clark, C.E., et al . 2009. Produced Water Volumes and Management Practices in

the United States

. A

SGE00188 O'Connell, James, ERG.2014. Pennsylvania Department of Environmental

Protection’s (PA DEP) Statewide Oil and Gas Waste Reports. (December) 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. 201 5 . Site Visit Report: Southwestern Energy (SWN) Fayetteville

Shale Gas Operations Sanitized

. A

25 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 f or company/organization websites that confirmed the author’s affiliation with the oil and gas industry.Memorandum

March 3 1 , 2015 Page 21

Table 5

. References Used for This Memorandum

DCN Source Citation Source Flag a

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

- 24.

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

SGE00739 ERG. 201 5

. Analysis of Pennsylvania Department of Environmental

Protection’s Oil and Gas Waste Reports. A

SGE00774 Ziemkiewicz, Paul. 2013. Water Quality Literature Review and Field

Monitoring of Active Shale Gas Wells. Phase I: Assessing Environmental Impacts of Ho rizontal Gas Well Drilling Operations. West Virginia Department of Environmental Protection. (Feb. 15). A

SGE00956 Madalyn S. Blondes, Kathleen D. Gans, James J. Thordson, Mark E Reidy, Burt

Thomas, Mark A Engle, Yousif K Kharaka, Elizabeth L Rowan. U.S. Geological Survey (USGS) National Produced Waters Geochemical Database v2.0 (PROVISIONAL)

. 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 Energy Information Administration (EIA). 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 Administrative Order Dated 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 Administrative Order 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 Pennsylvania Department of Environmental Protection (PA DEP) . 2015.

Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) Study Report. A

SGE01029 ICF Consulting. 2000. Overview o f Exploration and Production Waste Volumes

and Waste Management Practices in the United States. B

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 publication s). Source Flag C

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

SGE01016.A 0 1 )A TTACHMENT 2

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

SGE01016.A 0 2 )A TTACHMENT 3

– COG W ASTEWATER C HARACTERIZATION D ATABASE (DCN

SGE01016.A 0 3)A TTACHMENT 4

– USGS P RODUCED W ATER D ATABASE

– COG D ATA (DCN SG E01016.A 0 4)