BASELINE GROUND WATER QUALITY TESTING NEEDS IN THE EAGLE FORD SHALE REGION

By

Virginia E. Palacios

Dr. Robert B. Jackson, Advisor

April 2012

2012 Masters project submitted in partial fulfillment of the requirements for the Master of Environme ntal

Management degree in the Nicholas School of the Environment of Duke Universityi ABSTRACT

As the pace of drilling in the Eagle Ford shale increases, so does the potential for groundwater contamination

incidents. The goals of this analysis ar e (1) to determine whether existing baseline groundwater quality data

in the Eagle Ford shale region of south ern Texas is adequate to provide a comparison to potential future

contamination from oil and gas development and (2) to define an appropriate and cost

- effective list of

parameters that will aid in strate gic planning of baseline ground water quality testing in the Eagle Ford shale

region for the same goal.

First, a list of potential testing parameters is defined using case studies of proposed groundwat er

contamination. Second, formation water chemistry in the Eagle Ford shale region is compared to

groundwater chemistry in the counties of the Eagle Ford shale region to determine which chemical indicators

demonstrate potential to consistently detect cont amination. Third, statistical power analysis is used as a

guideline to decide whether more samples are needed for each testing parameter in each county in the Eagle

Ford shale region. Next, known health effects of each testing parameter are described in order to highlight

potential pollutants that should be prioritized in a sampling initiative. Finally, testing costs are reported to

introduce a perspective about microeconomic choices affecting which stakeholders take responsibility for

baseline groundwat er quality testing.

These tasks led to the findings that some of the most dangerous potential pollutants, including methane,

total petroleum hydrocarbons, nitrate, volatile organic compounds, polycyclic aromatic hydrocarbons, alpha

particles, beta particl es, and gamma radiation, are poorly characterized in the region, if at all. Furthermore,

testing these parameters is more expensive than testing less hazardous ones. Water well owners may be

unable to afford the expense of testing these parameters. Ther efore, a testing initiative facilitated by

agencies, industry, or other organizations may be more efficient at establishing a regional baseline for these

high priority, expensive tests. As such, the framework and analysis presented here can be used by

gro undwater managers in the Eagle Ford shale region to develop baseline sampling strategies tailored to

specific counties in the region.ii



## Acknowledgements

The idea for this p roject came from concerns expressed by residents of a small community in W ebb County,

Texas called “Los Botines.” After hearing about cases of potential groundwater co ntamination l inked to

hydraulic fracturing, the residents approached a non

- profit organization I was working for, the Rio Grande

International Study Ce nter (RGISC) , with questions about h ow to get baseline water q uality tests taken for

water wells in Los Botines

. After some research, my colleagues and I at RGISC found that comprehensive

baseline groundwater quality test ing would cost more than t he non

- profit coul d afford , and we speculated

that the expense would deter residents from pursuing testing on their own. W ith this in mind, the analysis

presented h ere seeks to e nable water well users, oil and gas companies , and agencies to better u nderstand

groundwater resources in the Eagle Ford shale region of South T exas.

M uch gratitude is owed to Tricia Cortez, Executive Director of RGISC, who has not only been a n outstanding

mentor, but also provided me with o pportunities to work with stakeholders on the gro und

. Additionally, my

t hanks go out to my fellow students at the Nicholas School of the Environment , especially those who are

members of the Drilling, Env ironment, and Economics Network ; and to members of the Laredo, Texas

- based

Safe Fracking Coalition, who engaged in o pen

- minded discussions about oil and gas development and were

always willing to share their e xpertise on relevant topics

. Finally, I greatly appreciate the time and feedback

offered by my advisor, Dr. Robert B. Jackson, who offered careful and thoughtful guidance throughout the

p rocess of writing this a nalysis.iii



## Contents

Acknowledgements

................................ ................................ ................................ ................................ .............. ii

Figures

................................ ................................ ................................ ................................ ................................ ... v

Tables

................................ ................................ ................................ ................................ ................................ ... vi

I. Introduction

................................ ................................ ................................ ................................ .................. 1

Geographic Scope

................................ ................................ ................................ ................................ ............. 3

Pathways and detection

................................ ................................ ................................ ................................ ... 4

Categories

................................ ................................ ................................ ................................ ......................... 5

Case Studies

................................ ................................ ................................ ................................ ...................... 6

i. Emergency Administrative Order: Range Resources (EPA 2010)

................................ ......................... 6

ii. Investigation of Ground Water Contamination near Pavillion, WY (EPA 2011)

................................ ... 7

iii. Methane contamination of drinking water accompanying gas

- well drilling and hydraulic fracturing

(Osborn et al . 2011)

................................ ................................ ................................ ................................ ...... 8

iv. Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources (EPA

2011)

................................ ................................ ................................ ................................ ........................... 10

v. Reported Groundwater Contamination in the Eagle Ford shale region

................................ ............ 12

II. Data and Methods

................................ ................................ ................................ ................................ ...... 14

Produced Water Data

................................ ................................ ................................ ................................ ..... 15

Groundwater Data

................................ ................................ ................................ ................................ .......... 18

Geospatial Analysis

................................ ................................ ................................ ................................ ......... 20

III. Results

................................ ................................ ................................ ................................ .................... 21

Testing priority codes

................................ ................................ ................................ ................................ ..... 21

A. Gas Hydrocarbons

................................ ................................ ................................ .............................. 21

B. Liquid Hydrocarbons

................................ ................................ ................................ .......................... 25

C. Salts

................................ ................................ ................................ ................................ .................... 28

D. Metals

................................ ................................ ................................ ................................ ................ 31

E. Naturally

- Occurring Radioactive Materials (NORM)

................................ ................................ .......... 32

F. Volatile Organic Compounds (VOCs)

................................ ................................ ................................ .. 35

G. Polycyclic Aromatic Hydrocarbons (PAHs)

................................ ................................ ......................... 37

IV. Discussion

................................ ................................ ................................ ................................ ............... 40

References

................................ ................................ ................................ ................................ .......................... 41iv

Appendix I

– Counties

................................ ................................ ................................ ................................ ......... 45

Appendix II

– Carbon isotope values

................................ ................................ ................................ .................. 46

Appendix III

– Starting list of potential testing parameters

................................ ................................ ................ 47

Appendix III

– Pavillion, WY test results

................................ ................................ ................................ .............. 49

Appendix IV

– RRC groundwater contamination report

................................ ................................ ..................... 51

App endix V

– Data preparation

................................ ................................ ................................ .......................... 53

USGS Produced Water Database

................................ ................................ ................................ .................... 53

Kearns (2010)

................................ ................................ ................................ ................................ .................. 53

TWDB Groundwater Database

................................ ................................ ................................ ........................ 53

Geospatial Analysis

................................ ................................ ................................ ................................ ......... 54

Literature Review

................................ ................................ ................................ ................................ ............ 54

Appendix VI

– Stratigraphic column

................................ ................................ ................................ ................... 55

Appendix VII

– Reliability codes for groundwater quality samples in Texas Water Development Board

database.

................................ ................................ ................................ ................................ ............................ 56

Appendix VIII

– TWDB Groundwater Database Listed Parameters

................................ ................................ .... 57

Appendix IX

– All Infrequent Constituents Identified in the TWDB Groundwater Database

............................. 58

Appendix X

- Carbon isotope ratios by depth

................................ ................................ ................................ ..... 62

Appendix XI

– Salts

................................ ................................ ................................ ................................ .............. 65

Produced water comparison with groundwater

................................ ................................ ............................ 65

Salts data availability

................................ ................................ ................................ ................................ ...... 67

Regulated salts data availabi lity

................................ ................................ ................................ ..................... 71

Appendix XII

– Metals: number of samples

................................ ................................ ................................ ........ 72

Appendix XIII

– Radionuclides: number of samples

................................ ................................ ............................ 77

Appendix XIV

– PAH samples

................................ ................................ ................................ .............................. 79v



## Figures

Figure 1 Acceleration of drilling activity in the E agle Ford shale (Railroad Commission of Texas 2012)

............. 1

Figure 2 Windows of oil, condensate, and gas in the Eagle Ford shale

................................ ................................ 2

Figure 3 Counties included in this analysis.

................................ ................................ ................................ .......... 3

Figure 4 Isopachs in the Eagle Ford shale. (adapted from Sellard et al. 1932 and Surles, 1987, Cited in Lai

1997)

................................ ................................ ................................ ................................ ................................ ..... 4

Figure 5 Number of pending cases of groundwater contamination attributed to oil and gas activities in

c ounties of the Eagle Ford shale region in 2010

................................ ................................ ................................ . 13

Figure 6 Total organic carbon concentrations in the counties of interest.

................................ ......................... 22

Figure 7 Geographic distribution of concentrations and samples of 13 C / 12 C stable isotope ratios.

................... 23

Figure 8 Groundwater concentrations of Total Petroleum Hydrocarbons in the counties of interest. Two

datapoints are found in the database, but their locations overlap on the map.

................................ ............... 26

Figure 9 Alpha particle concentrations in the counties of interest. Red points represent values greater than

the EPA MCL.

................................ ................................ ................................ ................................ ....................... 34

Figure 10 Benzene concentrations in the counties of interest. Points marked in re d indicate concentrations

that exceed the EPA MCL for benzene.

................................ ................................ ................................ .............. 36

Figure 11 Benzo(a)pyrene concentrations in the counties of interest.

................................ .............................. 38

Figure 12 Activity status for pending cases of groundwater contamination attributed to oil and gas activities

in 2010 (Texas Groundwater Protection Committee 2011).

................................ ................................ .............. 51

Figure 13 Map of the number of pending groundwater contamination cases caused by oil and gas activities

reported in 2010 (Texas Groundwater Protection Committee 2011).

................................ ............................... 52

Figure 14 Stratigraphic column of the Eagle Ford formation (Condon and dyman 2006, cited in Mullen 2010).

................................ ................................ ................................ ................................ ................................ ............ 55

Figure 15 13 C/ 12 C stable isoto pe ratios in groundwater by depth in the counties of interest.

.......................... 62

Figure 16 Counties where 13 C/ 12 C stable isotope ratio data for groundwater or core samples are available.

.. 62

Figure 17 Distributio n of carbon isotope ranges found in groundwater in Eagle Ford shale counties.

............. 63

Figure 18 Number, percent of total water wells, and groundwater testing needs for gas hydrocarbons with in

Eagle Ford shale counties. Testing c odes: a = as needed, r = recommended, t = testing needed

..................... 64

Figure 19 Total dissolved solids (TDS) concentrations in the Eagle Ford shale region.

................................ ...... 70vi



## Tables

Table 1 EPA isotopic fingerprint analysis of allegedly contaminated domestic well in Parker County, Texas

compared to commingled gas from the Butler and Teal gas wells.

................................ ................................ ...... 6

Table 2 Analytical tests used by Osborn, et al. (2011) to detect potential groundwater contamination caused

by shale gas extraction.

................................ ................................ ................................ ................................ ........ 9

Table 3 EPA Tier 2 Initial testing: sample types and tes ting parameters (Office of Research and Development

2011)

................................ ................................ ................................ ................................ ................................ ... 11

Table 4 Contaminants reported in groundwater contamination cases attributed to oil and gas activities in

2010 (Texas Groundwater P rotection Committee 2011)

................................ ................................ ................... 13

Table 5 Number of samples available in the TWDB groundwater database for general water quality

parameters in each county of the eagle ford shale region.

................................ ................................ ................ 19

Table 6 Values of 13C/12C isotope ratios found in potential Eagle Ford Source formations Comet (1993)

...... 24

Table 7 Cost of testing for ca rbon isotope ratios and total organic carbon with labs certified to test drinking

water in the state of Texas.

................................ ................................ ................................ ................................ 25

Table 8 Cost of testing for liquid hydrocarbons with labs certified to test dr inking water in the state of Texas.

................................ ................................ ................................ ................................ ................................ ............ 26

Table 9 EPA MCLs and Secondary Standards for salts and pH in groundwater (Environmental Protection

Agency 2012).

................................ ................................ ................................ ................................ ..................... 29

Table 10 Cost of testing, in USD, for various salts with labs certified to test drinking water in the state of

Texas.

................................ ................................ ................................ ................................ ................................ .. 30

Table 11 EPA Maximum Contaminant Levels (MCL ) and Secondary Standards for metals in drinking water and

associated health effects.

................................ ................................ ................................ ................................ ... 31

Table 12 Cost of testing, in USD, for metals with labs certified to test drinking water in the state of Texas.

... 32

Table 13 Types of radioactive emissions known to occur from various

................................ ............................ 33

Table 14 EPA Maximum Contaminant Levels for r adioactive elements/particles in drinking water

................. 34

Table 15 Cost of testing, in USD, for Radionuclides with labs certified to test drinking water in the state of

Texas.

................................ ................................ ................................ ................................ ................................ .. 35

Table 16 Number and percent of wells with reliable samples for which concentrations of BTEX chemicals are

found in the TWDB groundwater database.

................................ ................................ ................................ ....... 36

Table 17 Health effects of volatile organic compounds commonly found in oil and gas flowback

(Environmental Protection Agency 2012).

................................ ................................ ................................ .......... 37

Table 18 Cost of testing, in USD, for VOC with labs cer tified to test drinking water in the state of Texas.

....... 37vii

Table 19 Cost of testing, in USD, for PAH with labs certified to test drinking water in the state of Texas.

....... 38

Table 20 Categories of potential baseline groundwater chemistry parameters.

................................ .............. 47

Table 21 Contaminants found in monitoring wells drilled by the EPA in Pa villion, WY

................................ ..... 49

Table 22 Consolidated categories of RRC reported contaminants

................................ ................................ ..... 51

Table 23 Carbon isotope ranges for groundwater i n the counties of interest.

................................ .................. 6 3

Table 24 Wood County t

- test results for produced water compared to groundwater; All concentrations

measured in mg/l, except for pH.

................................ ................................ ................................ ....................... 65

Table 25 Wood County summary statistics. WW = produced water, GW = groundwater; All concentrations

measured in mg/l, except for pH.

................................ ................................ ................................ ....................... 65

Table 26 All Eagle Ford shale Counties: t

- test results for produced water compared to groundwater. TDS =

Total Dissolved Solids; All concentrations measured in mg/l, except for pH.

................................ .................... 66

Table 27 All Counties in th e Eagle Ford shale region: summary statistics. WW = produced water, GW =

groundwater. All concentrations measured in mg/l, except for pH.

................................ ................................ . 66

Table 28 Number, percent of total water wells, an d groundwater testing needs for salts found in produced

water in Atascosa, Austin, Bastrop, Bee, and Brazos Counties. Testing codes: A = As needed, R =

Recommended, T = Testing needed

................................ ................................ ................................ ................... 67

Table 29 Number, percent of total water wells, and groundwater testing needs for salts found in produced

water in Burleson, Caldwell, Colorado, Dewitt, and Dimmit Counties. Testing codes: a = as needed, r =

recommended, t = testing needed

................................ ................................ ................................ ..................... 67

Table 30 Number, percent of total water wells, and groundwater testing needs for salts found in produced

water in Duval, Edwards, Fayette, Frio, and Goliad Counties. Testing codes: a = as needed, r = recommend ed,

t = testing needed

................................ ................................ ................................ ................................ ............... 68

Table 31 Number, percent of total water wells, and groundwater testing needs for salts found in produced

water in Gonzales, Grimes, Guadalupe, Houston, Karnes Counti es. Testing codes: a = as needed, r =

recommended, t = testing needed

................................ ................................ ................................ ..................... 68

Table 32 Number, percent of total water wells, and groundwater testing needs for salts found in produced

water in La S alle, Lavaca, Lee, Leon, and Live Oak Counties. Testing codes: a = as needed, r = recommended, t

= testing needed

................................ ................................ ................................ ................................ ................. 68

Table 33 Number, percent of total water wells, and groundwater testing nee ds for salts found in produced

water in Madison, Maverick, McMullen, Milam, and Robertson Counties. Testing codes: a = as needed, r =

recommended, t = testing needed

................................ ................................ ................................ ..................... 69

Table 34 Number, perce nt of total water wells, and groundwater testing needs for salts found in produced

water in Washington, Webb, Wilson, Wood, and Zavala Counties. Testing codes: a = as needed, r =

recommended, t = testing needed

................................ ................................ ................................ ..................... 69viii

Table 35 Number, percent of total water wells, and groundwater testing needs for salts with primary

drinking water standards in Eagle Ford shale counties. Testing codes: a = as needed, r = recommended, t =

testing needed

................................ ................................ ................................ ................................ .................... 71

Table 36 Number, percent of total water wells, and groundwater testing needs for metals in Atascosa, Austin,

Bastrop, Bee, and Brazos Counties. A = As needed, R = Recommended, T = Testing needed

........................... 72

Table 37 Number, percent of total water wells, and groundwater testing needs for metals in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 72

Table 38 Number, percent of total water wells, and groundwater testing needs for metals in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 73

Table 39 Num ber, percent of total water wells, and groundwater testing needs for metals in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 73

Table 40 Number, percent of total water wells, a nd groundwater testing needs for metals in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 74

Table 41 Number, percent of total water wells, and groundwater testing needs for met als in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 75

Table 42 Number, percent of total water wells, and groundwater testing needs for metals in Counties. A = As

needed, R = Recommended, T = Testing needed

................................ ................................ ............................... 75

Table 43 Number of radionuclide samples available in the TWDB groundwater database for each county.

.... 77

Table 44 Number, percent of total water wells, and groundwater testing needs for radionuclide particle

emissions in Eagle Ford shale counties. A = As needed, R = Recommended, T = Testing needed

..................... 78

Table 45 Number and percent of samples out of the total number of water wells in each county for PAH

concentrations in groundwater.

................................ ................................ ................................ ......................... 791



## I. Introduction

Rapid increases in the pace of drilling activity in the Ea gle Ford shale play ( Figure 1 ) have created dual

pressures for landowners who also own mineral rights in the region

. These landowners theoretically have a

desire to collect income from leasing their mineral rights, but also have a preference for protectin g their

water quality. Recent developments in the technologies of horizontal drilling and hydraulic fracturing have

a llowed oil and gas extraction from low permeability formations, such as shale, to become more

economically viable ( Hughes 2011 ) . In shale plays 1 across the United States, drilling rates have increased

( Lippman Consulting and U.S. Ene rgy Information Administration 2010 )

. This increase in drilling activity could

be problematic however, because chemicals that flow back 2 out of oil and gas wells during extraction could

potentially cause groundwater to become contaminated with toxic ma terials ( Colborn, Kwiatkowski et al.

2011 )

.

F IGURE 1 A CCELERATION OF DRILL ING ACTIVITY IN THE E AGLE F ORD SHALE

( R AILROAD C OMMISSION OF T EXAS 2012 )

Recent proposed cases of groundwater contamination occurring after increase s in the rate of hydraul ic

fracturing in Texas, Pennsylvania, Wyoming, and other states have remained contentious because of the lack

of background water quality data available. “Background” water quality refers to the chemical characteristics

of the water before a change is mad e to the water body that could affect its chemical characteristics 3 . On

the one hand, oil and gas companies (industry) are aware of the opportunity for landowners to falsely claim

that contamination has occurred when if water quality problems already exi st . On the other hand,

landowners have been unable to find compensation for groundwater remediation when no comparison to

background water quality is available to indicate the source of contamination

.

As a shale play that is rich in liquids such as oil an d condensate ( Figure 2 )

, drilling activity in the Eagle

Ford is expected to continue accelerating. This is because liquids are currently more valuable than dry

gas ( U.S. Energy Information Administration 2011 ; U.S. Energy Information Administration 2012 )

. In

1 In oil and gas exploration, a “play” is a region where significan t quantities of oil and gas are expected to occur.

Schlumberger. (2012). "Oilfield Glossary." Retrieved April 24, 2012, from http://www.glossary.oilfield.slb.com.

2 The term “flowback” is used to describe the mixture of hydraulic fracturing fluids that returns to the surface

when th e well is producing. Flowback may contain produced water, hydraulic fracturing chemicals, and petroleum

hydrocarbons.

3 In this report, the term “baseline” will be used interchangeably with the term “background.”2

fact, the Energy Information Administration recently noted the Eagle Ford as a contributor in Texas’

significant gains in production for the year of 2011 ( U.S. Energy Information Administration 2012 )

.

In light of the potential for groundwater contamination to occur in the Eagle Ford shale region, it is

important to assess the strength of existing background water quality datasets in accurately predicting a

regional baseline of water quality. Additionally, it is important to determine geographic locations in the

region where more informati on is needed and what kind of chemical data is needed. The analysis

presented in this report finds that current available baseline ground water quality data is not adequate

to assess potential groundwater contamination from oil and gas exploration in the E agle Ford shale

region.

F IGURE 2 W INDOWS OF O IL

, C ONDENSATE

, AND G AS IN THE E AGLE F ORD S HALE

( U.S. E NERGY I NFORMATION A D MINISTRATION 2010 )

Current regulations and programs exist to facilitate baseline groundwater quality characterization, but to my

knowledge no widespread initiative exists to assist landowners or the oil and gas industry in the Eagle Ford

s hale region i n acquiring the appropriate tests needed to assess baseline water quality for the purpose of

detecting potential future contamination from oil and gas drilling, extraction, and production activities

(hereafter termed “oil and gas development”)

. Yet a ssess ing potential contamination of ground water wells

caused by oil and gas development relies on groundwater stakeholders, those who consume groundwater

and those who have the capacity to pollute groundwater, having access to appropriate and reliable

backgroun d water quality data ( Texas Administrative Code 2006 )

.

Studies assessing baseline ground water quality have ranged from testing few parameters to testing extensive

lists of potential contaminants and indicators. Baseline ground water quality testing should include a3

comprehensive list of parameters in order to be effective at detecting a wide range of potential contaminants

after oil and gas drilling takes place

. However, the expense of testing a comprehensive list of analytes 4 serves

to dissuade some water well owners from volunteering to conduct b ackground water quality testing on their

water well

. Considering this potential reaction, l imited resources should be spent on the most essential tests

that are effective in detecting constituents specific to oil and gas contamination.

Therefore, t he pur pose of this analysis is (1) to determine whether existing ba seline water quality data in the

Eagle Ford shale region is adequate to provide a comparison to potential future contamination from oil and

gas development and (2) to define an appropriate and co st

- effective list of parameters that would aid in

strategic planning of ba seline water quality testing in the Eagle Ford shale region for the same goal

.



## Geographic Scope

The data used in this analysis represents all Eagle Ford shale counties listed by th ree sources: Railroad

Commission, Energy Information Administration, and the website EagleFordShale.com. The 35 “counties of

interest” used in this analysis are depicted in Figure 3 and are listed in Appendix I.

F IGURE 3 C OUNTIES INCLUDED IN THIS ANA LYSIS

.

4 The term analytes refers to a chemical p arameter which must be analyzed, or tested, in a laboratory.4

One county included in this analysis, Wood County, is not in geographic proximity to the area of current

active Eagle Ford shale drilling. However, Wood County is included in this analysis because it is the only

county for wh ich U

. S

. G eological S urvey (USGS) produced water chemistry data for the Eagle Ford shale

formation was available. Produced water chemistry was documented in the USGS produced waters database

between the years of 1951 and 1975. The age of this data, and W ood County’s distance from the current

active drilling region of the Eagle Ford shale demands further supporting evidence that the formation

examined in Wood County is still taxonomically considered to be a part of the Eagle Ford formation.

Figure 4 depict s isopachs ( lines of equal thickness ) for the Eagle Ford shale . The area of Wood County

, depicted in Figure 4 East of Dallas, and in Figure 3 outlined in red, include s regions where the Eagle Ford

shale is known to exist at a thickness between 200 and 800 feet

. Therefore, although the USGS produced

waters data is old, Lai (1997) confirms that Wood County has been considered to contain portions of the

Eagle Ford formation more recently than 1975 . However, considerable uncertainty still exists as to whet her

produced water chemistry of the Eagle Ford formation in Wood County matches produced water chemistry

of the Eagle Ford formation in other counties.

F IGURE 4 I SOPACHS IN THE E AGLE F ORD SHALE

. ( ADAPTED FROM S ELLARD ET AL

. 1932 A ND S URLES

, 1987

, C ITED IN L AI 1997)



## Pathways and detection

This report does not include analysis of the potential pathways through which groundwater contamination

from oil and gas extraction activities could occur. However, for the sake of understandin g a comparison

between baseline ground water quality and potentially contaminated ground water quality, these pathways

are outlined in this section. A pathway can be defined as a continuous space between a hydrocarbon

- bearing5

formation and a groundwater aqu ifer. Four potential pathways have been postulated in previous research

( U.S. General Accounting Office 1989 ; Environmental Protection Agency 2011 ; Osborn, Vengosh et al. 2011 ) 5 :

1. Natural migration of fluids and gases from the formation to the aquifer

2. Leaky oil or natur al gas well casings

3. Induced fractures connect ing with or enlarg ing existing natural fractures

4. Induced fractures connect ing with abandoned oil and gas wells

If the pathways are present, fluids and/or hydrocarbon gases that were naturally occurring or which were

injected into the oil and gas formation could mix with groundwater. In order to detect potential

contamination, the concentration of potential contaminants flowing from the hydrocarbon

- bearing

formation into the groundwater aquifer must be higher th an the concentration of the same pre

- existing

chemicals in the groundwater aquifer. Additionally, the potential contaminant must enter the aquifer at a

rate that is greater than the groundwater flow rate, or else the contaminant would be diluted to a leve l that

is not different from the pre

- existing background water quality. Although expected concentrations are

compared in this report, groundwater flow modeling is outside the scope of the analysis presented here.

Mixing of petroleum

- hydrocarbon gases, su ch as methane, in an aquifer can be detected through

measurements of total organic carbon. However, carbon

- 13 ( 13 C) isotopes have been used in numerous

cases to detect contamination from hydrocarbons. A description of how 13 C isotopic signatures are meas ured

is provided in Appendix II. The change in concentration of 13 C isotopes in an aquifer can help to determine

whether gas found in the aquifer was sourced from a specific formation that was explored for natural gas.

Although this test provides a usefu l indication of whether contamination was caused by oil and gas

development activities, without a strong dataset of background carbon isotope values it is difficult to prove

whether the post

- drill δ 13 C concentrations matching those found in a shale formation were pre

- existing or

not

.



## Categories

The case studies that are described below list potential groundwater quality parameters that can be used to

detect potential contamination from oil and gas development . Those parameters have been grouped into

the following seven categories:

1. Gas hydrocarbons

2. Liquid hydrocarbons

3. Salts

4. Metals

5. Radionuclides

6. Volatile organic compounds (VOC)

7. Polycyclic aromatic hydrocarbons (PAH)

The complete list of parameters attributed to each categ ory can be found in Appendix III, Table 2 0

. A

characterization of the data available for these parameters, their efficacy for the intended purpose, their

known health effects, and costs of testing each parameter will be described in the results section. All of this

information is used to generate a list of the most essential baseline ground water quality parameters for the

Eagle Ford shale region and to support recommendations for future testing initiatives.

5 Cited in Sumi, L. (2005). Our Drinking Water at Risk. Durango, CO, Oil and Gas Accountability Project,.6



## Case Studies

In the pa st decade, several prominent studies have linked groundwater quality changes to potential

migration of hydraulic fracturing fluids, produced water, and/or petroleum hydrocarbons into aquifers. The

results of these studies were questioned, however, because baseline water quality data was not available for

a comparison with potentially contaminated groundwater samples. The cases described here are used to

generate a list of potential baseline groundwater quality testing parameters for the Eagle Ford shale r egion.

This discussion is not intended to provide a comprehensive analysis of all cases of potential groundwater

contamination that have been linked to hydraulic fracturing. Rather, these cases point to the complex nature

of proving contamination through the scientific process, and the need for more baseline ground water quality

testing of specific chemicals.



### i. Emergency Administrative Order: Range Resources (EPA 2010)

In the summer of 2010 the EPA issued an emergency order to Range Resources Company to inv estigate and

remediate contamination of two domestic water wells lying within the Barnett shale in Parker County, Texas

( Environmental Protection Agency 2010 ) . Private tests, RRC tests, and EPA tests of one water well indicated

that concentrations of volatile organic compounds (VOC) and gas hydrocarbons including benzene 6 (C 6 H 6 )

, toluene (CH 3 )

, propane (C 3 H 8 ) , hexane (C 6 H 14 ) , ethane (C 2 H 6 ) , and dissolved methane (CH

4 ) were present

( Wilson, Sumi et al. 2011 ) . Tests by the RRC showed benzene and toluene levels in excess of federal

Maximum Contaminant Levels (MCL) for drinking water ( Environmental Protection Agency 2012a ;

Environmental Protection A gency 2012b ) . Subsequent tests by the EPA returned lower values than the RRC

found, however toluene concentrations were still above the MCL. Additionally, the EPA’s analyses of

methane isotopes (δ 13 C

– CH 4 and δD

– CH 4 ) in the water well returned values n early identical to the isotopic

signature of methane and hydrogen that was prod uced from two nearby gas wells, as seen in Table 1

( Environmental Protection Agency 2010 )

.

T ABLE 1 EPA ISOTOPIC FINGERPRINT ANALYSIS OF ALLEGEDL Y CONTAMINATED DOMES TIC WELL IN

P ARKER C OUNTY

, T EXAS COMPARED TO COM MINGLED GAS FROM THE B UTLER AND T EAL GAS WELLS

.

Domestic w ater well Natural Gas well

δ 13 C

– CH 4 - 47.05

- 46.60

δD

– CH 4 - 188.5

- 183.9

Critics of the EPA’s actions toward Range Resources state that the gas was pre

- existing , and that no lack of

wellbore integrity was found, implying that there was no possible way for the fluid and gas migrati on to have

occurred as a result of Ra nge Resources’ activities ( Smitherman and Porter 2012 ) . Background water quality

data for the hydrocarbons found in the investigation may have allowed a more robust conclusion. As such

, this analysis includes a characterization of known background concentrations for t h e following VOC and gas

hydrocarbons :

6 Benzene, toluene, ethylbenzene, and xylene (BTEX) are volatile organic compounds (VOCs) which are generally

known to occur in oi l and gas formations. BTEX are also found in diesel fuel, which is sometimes used in hydraulic

fracture treatments. Source: Leusch, F. and M. Bartkow (2010). A short primer on benzene, toluene, ethylbenzene

and xylene s (BTEX) in the environment and in hydraulic fracturing fluids. G. University and S. W. R. Centre.7

Category Potential baseline chemical analytical parameter

Gas hydrocarbons Methane

Ethane

Propane

Hexane

VOC Benzene

Toluene

ii. 

### Investigation of Ground W ater Contamination near Pavillion, W Y (EPA 2011)

The EPA recen tly issued a draft report analyzing results from alleged cases of contamination in Pavillion, WY

( Environmental Protection Agency 2011 ) . In this study, the EPA performed tests for an extensive list of water

quality parameters . Categories describing these parameters are listed below

.

Elevated levels of methane and DRO were found in domestic water wells in the vicinity of natural gas wells in

Pavillion, WY ( Environmental Protection Agency 2011 ) . The EPA installed two monitoring wells into the

groundwater aquifer in order to determine the presence of potential contaminants in the aquife r. Tests of

the two monitoring wells found VOC, synthetic compounds, and components of compounds that had been

used in hydraulic fracturing at the site (Appendix III , Table 20 ).

The EPA concluded that leaching from hydraulic fracturing fluid disposal pi ts and possibly leaks in the

wellbore cement casing had allowed contaminants to migrate to the aquifer. Critics have asserted that the

EPA’s conclusions were based on limited data and that installation of the monitoring wells may have been the

sources of contamination that the EPA found ( Railroad Commission of Texas 2012 )

.

Not surprisingly, t he final p aragraph of the EPA draft investigation of Pavillion, WY states:

"Collection of baseline data prior to hydraulic fracturing is necessary to reduce investigative costs and

to verify or refute impacts to groundwater

... this investigation supports recommendatio ns made by

the U.S. DOE Panel on the need for collection of baseline data, greater transparency on chemical

composition of hydraulic fracturing fluids

, and greater emphasis on well construction and integrity

requirements and testing."

This conclusion aris es from speculation that the organic and inorganic contaminants found at the site might

be expected to occur naturally, considering that the region has been targeted for oil and gas exploration ( U.S.  Major anions and alkalinity

 Diesel Range Organics (DRO)

 Se mi

- Volatile Organic Compounds (s VOC)

 Total petroleum h ydrocarbons (TPH)

 Pesticides

 Total p hase

- separated h ydrocarbons

 Polychlorinated B iphenyls (PCB)

 Alcohols and Volatile Organic

Compounds (V OC)

 Total I norganic C arbon (TIC)

 Bacteria

 Metals

 Low molecular weight acids

 Gasoline Range Organics (GRO)

 Fixed gas isotopes8

Energy Information Administration 2010 ) . Such speculation underscores the importance of baseline testing.

However, testing for all of the categories described above is not necessary. From the list of testing categories

described above

, sVOC, TIC, Pesticides, PCB, bacteria, and low molecular weight acids were not included in

this analysis , but the other parameters are included . Reasons for omitting these parameters from the

analysis are explained below

.

First, sVOC are an indication of the presence of dispersed oil droplets in water ( Neff, Sauer et al. 2011 )

. While

a test for sVOC would provide an indic ation of the presence of petroleum hydrocarbons in water, VOC are

non

- essential parameters for baseline groundwater quality testing if petroleum hydrocarbons are tested in

other ways

.

Next, TIC is a category that is used to detect products of chemical int eractions between produced water and

groundwater ( Environmental Protection Agency 2011 ) . TIC includes parameters such as bicarbonate (HCO 3 - )

and calcite (CaCO 3 ). Bicarbonate i s characterized in this analysis, but only in the context of an expected

change in concentration if produce d water breaches an aquifer. TIC, including CaCO 3 , are not considered as

parameters in this analysis, because a baseline ground water quality analysis only needs to look for pre

contamination constituents, rather than examining expected products of chemica l interactions between the

potential contaminants and background water components.

Finally, Pesticides, PCB, bacteria, alcohols and low molecular weight acids are not included in the categories

that will be characterized in this report, because they eithe r represent potential contamination from sources

other than oil and gas ; or these parameters would provide non

- essential supporting evidence of

contamination that can be determined more simply by a sample’s comparison with the one or more of the

other esse ntial baseline water quality parameter s

.

Considering these factors, this analysis includes a characterization of known background data availability , and

some background concentrations, for the following parameters which correspon d to the seven categorie s

previously listed 7 :

Category Potential baseline chemical analytical parameter

Gas hydrocarbons Fixed gas isotopes (carbon isotopes)

Liquid hydrocarbons T otal P etroleum H ydrocarbons (TPH)

G asoline R ange O rganics (GRO)

D iesel R ange O rganics (DRO)

Salts Major anions and alkalinity ( Na + , K + , Ca 2+ , Mg 2 + , Cl - , SO 4 2

- , F -

, NO 3 - )

Metals Al, Ag, B, Ba, Be, Ca, Co, Fe, K, Mn, Mo, Na, Sb, Sr, Ti, Zn, S, P, As

, Cd, Cr, Cu, Hg, Ni, Pb, Se, U

VOC Benzene, toluene, ethylbenzene, xylene ( BTEX )



### iii. Methane contamin ation of drinking water accompanying gas

- well drilling

and hydraulic fracturing (Osborn et al. 2011)

One example of the difficulty that is presented in using δ 13 C isotope concentrations for determining whether

groundwater contamination occurred is offered by Osborn et al. (2011) and Molofsky et al. (2011). Osborn

et al. (2011) found a correlation between the concentrations of dissolved methane found in domes tic water

wells and the proximity of those water wells to hydraulically fractured natural gas wells. The researchers

7 Analytical parameters described here are based on those tested in the Pavillion, WY EPA Investigation.9

concluded that water wells within 1 km of a hydraulically fractured natural gas well were more likely to have

high concentrations of metha ne in their water wells, sometimes dangerously high, and that this

contamination may have been caused by shale gas extraction ( Osborn, Vengosh et al. 2011 ) . Table 2 lists the

tests that were used to reach this conclusion. Among the tests used, carbon isotopic values for methane

( δ 13 C

- CH 4 ) indicated that methane sourced from the Marcellus shale was present in high concentrations in

water wells that were in close proximity to hydraulically fractured natural gas wells.

T ABLE 2 A NALYTICAL TESTS USED BY O SBORN

, ET AL

. (2011) TO DETECT POTENTIAL GROUNDWATE R

CONTAMINATION CAUSED BY SHALE GAS EXTRACT ION

.

Test Purpose Conclusions of Osborn et al.

Methane, ethane, and propane

isotopes and concentrations Indicates whether gas

contamination is present

I sotopes, and ethane/propane

ratios help to determine the

s ource of the gas I sotopic signature of the methane

found in the water wells matched

the isotopic fingerprint of gas from

the Marcellus formation,

indicating that contamination had

occurred ; presence of ethane and

propane in the ratios found

supports the co nclusion that gas

migrated from the shale.

δ 13 C

- DIC, δ 18 O, and δ 2 H Indicators of microbial methane No positive correlation between

δ 13 C

- DIC and δ 13 C

- CH 4 , indicating

that methane was not formed by

microbes. No correlation between

δ 2 H found in water and δ 2 H found

in methane at the site, indicating

that the methane was not formed

in the shallow aquifer ; δ 18 O

composition was of modern

meteoric origin, indicating that it

did not come from an older,

deeper formation.

δ 11 B, δ 226 Ra

Major cations (Na + , Ca +2 , Mg +2 )

Major anions (Cl - , Br - , NO 3 - SO 4 - 2 )

Trac e metals

Alkalinity as HCO 3 - Additional indicators of potential

mixing with deep formation waters Samples matched background

data, therefore no contamination

from formation fluids could be

verified.

Molofsky et al. (2011) have questioned the conclusions of Osborn et al. (2011) that higher concentrations of

methane in water wells near natural gas wells indicated that contamination had occurred after drilling.

Rather, Molofsky et al. (2011) contended that water wells positioned in valleys tend to have hig her

concentrations of methane than water wells in uplands. Therefore, they posit that this relationship may have

skewed the results of Osborn et al. (2011). Additionally, they questioned the interpretation that the isotopic

signatures of methane found in the water wells were sourced from the Marcellus shale, and offered an

interpretation that suggested the methane was from a separate nearby formation. Nonetheless

, Molofsky et

al. (2011) cite the need for background isotopic data in order to determine if potential contamination has

occurred as a result of gas extraction and production ( Mo lofsky, Connor et al. 2011 )

.10

Taking this into consideration, baseline groundwater testing of carbon isotopes is an essential tool for

assessing whether oil and gas drilling activities have affected an aquifer. Contrastingly, parameters that are

non

- es sential for baseline ground water quality testing are water isotopes ( δ 18 O and δ 2 H) and boron isotopes

( δ 11 B). Water and boron isotopes are used with concentrations of δ 13 C isotopes as additional supporting

evidence that defines which formation the hydroca rbons were sourced from ( Osborn, Vengosh et al. 2011 ) ;

therefore, knowin g the concentr ation of water and boron isotopes is non

- essential if δ 13 C concentrations

from a background water quality test are available for comparison to a potentially contaminated sample of

water. As such, the following parameters are considered in this analysis:

Category Potential baseline chemical analytical parameter

Gas hydrocarbons Methane

Ethane

Propane

Carbon isotopes

Salts Major cations and anions ( Na + , Ca +2 , Mg +2

, Cl - , Br -

,

NO 3 - SO 4 - 2 )

Alkalinity as HCO 3 -

Metals Trace metals, although not listed in Os born et al.

(2011) or supplemental information, this category

corroborates that metals should be tested.



### iv. Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking

Water Resources ( EPA 2011)

The EPA is currently conducting a study on the po tential impacts of hydraulic fracturing on drinking water

resources ( Office of Research and Deve lopment 2011 )

. In an attempt to be comprehensive, the final study

plan contains a list of chemicals found in hydraulic fracturing fluids and flowback water that spans 25 pages.

The list is long primarily due to the extensive number of potential chemical s that have been or will be used in

hydraulic fracturing at the sites considered in the study

.

Due to the expense of test ing so many parameters , the EPA has selected five retrospective case studies out of

a list of 45 nominated cases, and two prospecti ve case studies out of a list of seven possible candidates 8 . The

retrospective case studies will examine cases where hydraulic fracturing was alleged to have caused

groundwater contamination, and in the prospective case studies the EPA will examine sites where drilling has

not yet occurred. The prospective case studies will allow the EPA to gain understanding of all possible

pathways of contamination and how to detect when contamination has occurred if that is the case.

The EPA plan to study the poten tial impacts of hydraulic fracturing on drinking water resources points out

that interferences can complicate analytical approaches used to characterize samples associated with

hydraulic fracturing :

“Some gases and organic compounds can partition out of t he aqueous phase into a non

- aqueous

phase (already present or newly formed), depending on their chemical and physical properties. With

the numbers and complex nature of additives used in hydraulic fracturing fluids, the chemical

composition of each phase d epends on partitioning relationships and may depend on the overall

composition of the mixture. The unknown partitioning of chemica ls to different phases makes it

8 The rationale behind the EPA’s selection of case s tudies is available in their report titled “Plan to Study the

Potential Impacts of Hydraulic Fracturing on Drinking Water Resources” and will not be discussed here.11 difficult to accurately determine the quantities of target analytes. In order to address this issue, EPA

has asked for chemical and physical properties of hydraulic fracturing fluid additives in the request for

information sent to the nine hydraulic fracturing service providers.” (EPA 2011, p.166)

These complications are illustrative of the challe nge that landowners and agencies are faced with in

conducting post

- drill water quality testing for the purpose of detecting potential contamination from oil and

gas drilling, extraction, production, and waste storage activities. Although the EPA has acces s to the list of

chemical and physical properties of hydraulic fracturing fluid additives from the se nine service providers, this

kind of information is not publically available for all wells in the United States. Even Texas’ landmark

disclosure bill pass ed in the summer of 2011, H.B. 3328, allows oil and gas companies not to disclose

chemicals considered to be trade secrets 9 ( H.B. 3328, 2011 ) . Additionally, a well operator is not required to

disclose the list of chemicals used in the hydraulic fracturing treatment until after the well has been

completed . Therefore, if a hypothetical landowner in Texas desires to test her water well for hydraulic

fracturing fluid components before drilling takes place, she must choose her baseline ground water quality

tests using a general list of hydraulic fracturing flu ids known to have been used in her region. Testing for

region

- based hydraulic fracturing fluids would not only be expensive, but it might also be irrelevant since

hydraulic fracturing fluid mixtures vary from well to well and because chemical formulas for hydraulic

fracturing fluids are constantly changing. Based on this reasoning, baseline ground water quality testing

would be greatly enhanced if oil and gas well drillers conducted the tests before drilling using a list of

parameters tailored to the hydra ulic fracturing fluid mixture that is used at each site.

The list of intended testing parameters , not including hydraulic fracturing fluids, for the EPA’s prospective

case studies is provided in Table 3

.

T ABLE 3 EPA T IER 2 I NITI AL TESTING : SAMPLE TYPES AND TES TING PARAMETERS ( O FFICE OF R ESEARCH

AND D EVELOPMENT 2011 )

O ut of the parameters listed for groundwater in Table 3, redox potential and dissolved oxygen will not be

9 Landowners, neighbors and agencies are allowed to challenge a trade secret provision with in two years from the

date the well completion report is filed.12

consider ed in this analysis because neither would provide definitive evidence of contamination if

concentrations with a potentially contaminated sample were compared with background water quality

. Rather, both redox potential and dissolved oxygen are non

- essential parameters that serve to support

conclusions drawn from other analyses. Additionally, sVOC are not considered for the same reason

. Based

o n these decisions, t he parameters listed below will be considered in this analysis.

Category Potential baseline chemical analytical parameter

Salts TDS

Cations and anions

Barium

Strontium

Chloride

Boron

Metals Arsenic

Barium

Selenium

Radionuclides Radi um

VOC BTEX

PAH Not reported



### v. Reported Groundwater Contamination in the Eagle Ford s hale region

The Railroad Commission of Texas (RRC) is the agency that has jurisdiction over contamination of

groundwater associated with exploration, development, or pr oduction, including storage or transportation,

of oil and gas ( Texas Groundwater Protection Committee 2011 )

. As a part of the Te xas Groundwater

Protection Council (TGPC), the RRC submits an annual compilation of all pending or completed cases of

contamination 10 in the state of Texas ( Texas Groundwater Protection Committee 2011 )

. This is useful for

determining which contaminants are expected and should be tested for in a baseline ground water quality

test.

Here, all of the cases reported by the RRC for the 3 5 counties of interest in the Eagle Ford shale region were

compiled. However, cases of contamination were listed for only 21 out of the 3 5 counties (Figure 5)

. The

counties with the most cases of contamination were Austin, Webb, Wood, Bee, Duval, and Lava ca. The

counties in which no contamination was reported are depicted in Appendix IV, Figure 20.

10 These cases represent incidents where “t he detrimental alteration of the naturally occurring physical, thermal,

che mical, or biological quality of groundwater” has occurred according to TAC, Title 31, Part 18, Chapter 601,

Subchapter A, Rule § 601.2.13

F IGURE 5 N UMBER OF PENDING CASES OF GROUNDWATER CONTAMINATION ATTRIBUTED TO OIL AN D GAS

ACTIVITIES IN COUNTIES OF THE E AGLE F ORD SHALE REGION IN 2010

Contaminants found in these cases are listed in Table 4 , below . In compiling the reported cases for analysis,

some reported contaminant s were consolidated into one category that most accurately represent ed that

co ntaminant (Appendi x IV, Table 22 ). Out of the 64 cases of reported contamination , only four were new

cases in the year 2010. The status of the case investigations can be found in Appendix IV, Figure 15

.

T ABLE 4 C ONTAMINANTS REPORTED IN GROUNDWAT ER CONTAMINATION CASES ATTRIBUTED TO OIL AND

GAS ACTIVITIES IN 2010 ( T EXAS G ROUNDWATER P ROTECTION C OMMITTEE 2011 )

*National Secondary Drinking Water Standard

BTEX chemicals and liquid hydr ocarbons were the most frequent contaminants reported in 2010 (Table 4 ).

Included in Table 4 are the EPA MCLs and Secondary Standards for each of the contaminants found in the

counties of interest in the 2010 report 11 . However, it should be noted that no concentrations of the chemical

contaminants are provided in the joint report. Therefore, no comparison can be made between an expected

concentration that would be found in the shale formation and the expected concentrati o n that would be

found in groundwat er. Nonetheless, out of the list of potential contaminants in Table 4, all are included in

th is analysis

, and are represented by the following parameters:

Category Potential baseline chemical analytical parameter

11 Potential hazards and human health effects attributed to each of these contaminants are discussed in the results

section. 3 10

1 5

2

1 3 3 5

1 1 1 2

1 1 2 3

2 5 6 6

0 2 4 6 8 10 12 Number of cases in process

County

Contaminant Co unt EPA MCL

Liquid hydrocarbons 27 NA

BTEX 25 0

- 10 mg/l

Chlorides 7 250 mg/l*

Gas hydrocarbons 2 NA

Arsenic 1 0 mg/l

Barium 1 2 mg/l

Metals (not defined) 1 NA

Total 6414

Gas hydrocarbons Methane

Liquid hydrocar bons Total petroleum hydrocarbons 12

Salts Chloride

Sodium

Metals Arsenic

Barium

Radionuclides Radium

VOC BTEX

PAH Not reported



## II. Data and Methods

As stated in the introduction

, the objectives of this analysis are (1) to determine whether existing basel ine

ground water quality data in the Eagle Ford shale region is adequate to provide a baseline for comparing to

potential future contamination from oil and gas drilling, and (2) to define an appropriate and cost

- effective

list of parameters that would aid i n strategic planning of baseline ground water quality testing in the Eagle

Ford shale region for the same goal. To achieve these objectives, a list of essential parameters was

established first, using the case studies described in the previous section

. Se cond, using the list of essential

parameters

, the available groundwater data for those contaminants in the counties of interest is described ;

when possible, this data is compared to concentrations of the same parameters known to occur in the Eagle

Ford sha le formation. Finally, recommendations for testing efforts are made based on data needs, whether

health effects are known to occur for each parameter , and the cost of each test.

In characterizing the baseline data available for each county, t he number of samples available in each county

is given for each parameter , and general statistical principles are used to determine whether enough samples

are present . If an EPA Maximum Contaminant Level (MCL) or Secondary Standard 13 for drinking water has

been set fo r the parameter of interest, a map was drawn depicting the known concentration at each sample

location. Additionally, maps are depicted for selected parameters of interest that have not been assigned an

MCL or Secondary Standard by the EPA , but which are particularly useful in detecting potential

contamination

.

In order to define which general chemistry parameters would be the best indicators of an influx of flowback

or hydrocarbons into a groundwater well, chemical concentrations from the USGS Produced Wa ters database

were statistically compared to groundwater quality for the counties of interest . This allowed for some

chemical tests to be removed from the list of recommended tests because the parameters are ne ither

12 TPH encompasses all of the contaminants listed in Appendix IV, Table 29.

13 Maximum Contaminant Levels (MCLs) are “ National Primary Drinking Water Regulations (NPDWRs or

primary standards) are legally enforceable standards that apply to public water systems. ” and “National

Secondary Drinking Water Regulations (NSDWRs or “sec ondary standards”) are non

- enforceable

guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration)

or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary

standards to wa ter systems but does not require systems to comply.”

Environmental Protection Agency. (2012, March 6, 2012). "List of Contaminants & their MCLs." Drinking

Water Contaminants Retrieved M arch 13, 2012, 2012, from

http://water.epa.gov/drink/contaminants/index.cfm.15

dangerous to human health nor are they expected to cause a substantial change in concentration when

mixed with groundwater.

In addition to comparisons made between the TWDB groundwater database and the USGS produced waters

database, a systematic literature review was conducted to determine whet her additional potential

contaminants that might be found in t he Eagle Ford shale . Additionally, this served to establish expected

concentrations for known contaminants expected to occur in the Eagle Ford formation . Although the results

of this attempt w ere generally not substantial enough to use in a statistical comparison with groundwater,

some references that were found in this process are used throughout the sections to support various

findings. The lack of findings in this attempt demonstrates that more publically available data is needed

about the produced water chemistry of the Eagle Ford shale formation.

Finally, q uotes were requested from all laboratories listed by the Texas Commission on Environmental

Quality (TCEQ) as certified to test samples in the drinking water category in the state of Texas. These 83

labs 14 are certified under the National Environmental Laboratory Accreditation Program (NELAP). Twenty of

the 83 labs replied to the request. These data are used qualitatively to make general recommendations

about whether organizations or landowners should be expected to conduct a sampling effort. For more

expensive tests, it might be l ess likely that landowners will actively pursue a water analysis for those tests.

For this reason, a strate gic sampling effort in regions that have less publically available information on these

more expensive analytes might best be taken on by an agency , industry, or other organizations

.



## Produced Water Data

Produced water can be defined as the water that is n aturally occurring in the formation where oil and gas

exploration occurs. During the production phase of an oil and gas well, produced waters flow out of the well,

along with hydraulic fracturing fluids that were used in the well, and any hydrocarbons pre sent in the

formation. Produced water contains a variety of chemicals that occur naturally in a formation. Since

produced water is known to occur in the Eagle Ford shale formation at moderate to high volumes ( Lai 1997 ;

Hsu and Nelson 2002 ; Mullen 2010 ; Mullen, Lowry et al. 2010 ) 15 , it is conceivable that if a pathway between a

hydrocarbon

- bearing formation and an aquifer exists, the n produced water chemistry would cause a change

in chemical con centrations found in the aquifer. A comparison between the chemistry of produce d water

and the chemistry of groundwater in the counties of interest is used to identify which chemical parameters

are expected to be the most different, and will therefore serve as good indicators of contamination.

The USGS provides a database of concent rations of general chemistry parameters for produced waters from

multiple formations in each state ( Breit, Skinner et al. 2006 )

. Procedures used to prepar e the dataset for

analysis are listed in Appendix V. The information contained in the database was offered voluntarily by

various companies ( U.S. Geological Survey 2002 )

. Only 36 records were availab le for the Eagle Ford

formation, although 1606 records were available for other formations in the counties of interest. The

14 Some labs were not considered if they did not test any of the chemicals of interest for this report (e.g. if the lab

only tested for total coliforms).

15 According to Lai (1997) , Hsu and Nelson (2002), Mullen 2010, and Mullen, Lowry et al. (2010), the average water

content of the Eagle Ford shale formation is 16 to 19 percent. Additionally, Mullen, Lowry et al. (2010) reported a

case where high water volumes in the Eagle Ford sh ale at depths of 15,230 feet prevented flow of gas from the

well.16

samples for the Eagle Ford formation were taken between the years of 1951 and 1975 , while samples for

other formations in the count ies of interest were taken between 1929 and 1980.

Water quality parameters that are provided in both the produced waters database and the groundwater

database include:

 pH

 Chloride

 Sodium

 Bicarbonate

 Magnesium

 Sulfate

 Calcium

 Potassium

 TDS

Nonethel ess, using this dataset for the Eagle Ford shale formation may not be an accurate representation of

Eagle Ford shale produced water chemistry in other counties, because all of the data representing the Eagle

Ford formation are from wells drilled in Wood Co unty 16 . This is problematic, since Wood County is not

currently in the active drilling area of the Eagle Ford shale. This fact raises doubts about whether the data

that was labeled as “Eagle Ford” in the USGS produced waters dataset is still considered to be from a

formation that is within the boundaries of the Eagle Ford formation.

As it turns out, the samples taken for Wood County represent depths ranging from 4200 feet

– 5800 feet.

Although oil and gas wells have recently been drilled in Wood County at those depths, the wells are

categorized in the Woodbine and Sub

- Clarksville formations 17 . The Sub

- Clarksville formation underlies the

Eagle Ford ( Holbrook 1985 ) , but the Woodbine form ations and Eagle Ford are undivided in portions of

northeast Texas ( U. S. Geological Survey ; Condon and Dyman 2006 ) 18

. Therefore, although the produced

waters data for the Eagle Ford are in fact representing the Eagle Ford formation, the fact that portions of the

Eagle Ford and Woodbine are undivided could mean that Eagle Ford pro duced water samples are chemically

different in Wood County compared to counties in the active drilling area

.

A lthough a statistical comparison of produced waters and groundwater in Wood County is described in this

analysis, it should be understood that a high level of uncertainty is embodied in the analysis . More produced

water data is needed for the active drilling area in order to draw a relevant and accurate comparison

between Eagle Ford s hale produced water and groundwater in the counties of interes t

.

In order to understand, in a general sense, how produced water chemistry differs from groundwater

chemistry, data from other formations in the counties of interest was compared to groundwater chemistry in

the counties of interest. Such an analysis is u seful for guiding future research, but more chemical data from

Eagle Ford produced water is still needed to learn which parameters will be most useful for baseline testing

in the active drilling region.

In addition, other sources provide some indication of expected elements in the Eagle Ford formation, but the

only available data is for core samples. Kearns (2011) provides geochemical analysis of Eagle Ford core

samples for major elements, trace elements, and isotopes. This data is described further in appe ndix V.

16 One record in the Eagle Ford shale was documented in Houston County, but this record was not used to allow

for a simpler comparison of Wood County produced water and groundwater data.

17 The RRC approved 55 drilling permits for Wood County wells from 01/01/2009 to 01/01/2012, and six of those

wells were within the depth range of 4200

– 5800 feet. Records on the Railroad Commission W

- 1 Permit

Application database indicate that these wells were drilled into a Sub

- Clarksville and Woodbine formation.

18 Eagle Ford stratigraphy is shown in Appendix VI, Figure 20.17

Other sources indicate the presence of sulfur (S), nickel (Ni), vanadium (V), aluminum(Al), iron (Fe), calcium

(Ca), silicon (Si), and zircon(Zi) in core samples ( Comet, Rafalska et al. 1993 ; Mullen 2010 ) . Although this

informatio n could guide future research, it is not as useful for comparing to liquid concentrations since the

solubility of the elements in the core samples is unknown. However, values of δ 13 C isotopes in the Eagle Ford

provided by Kearns (2010) and Comet (1993) co uld be useful for a comparison with groundwater δ 13 C

isotopes. This comparison is described in the results section.18



## Groundwater Data

Data from the Texas Water Development Board’s (TWDB) groundwater quality database 19 was used to

d etermine if enough samp les are available to establish a reliable distribution of potential baseline

concentrations, where comparisons can be made between baseline groundwater quality and groundwater

samples that have potentially been contaminated by oil and gas activities. Addi tionally, as mentioned above,

the groundwater quality data was compared to produced water concentrations when possible to determine

which chemicals in each county exhibit the greatest differences and are therefore more likely to serve as a

reliable indicat or of contamina tion.

Table 5 depicts the number of samples available for each county in the Eagle Ford shale region. The samples

were taken between the years of 1988 and 2011. Additionally, the number of samples taken with reliable

methods, the number of individual wells that are represented in the pools of samples, and the number of

wells with more than one sample are provided. Not depicted in the table are the total numbers of

groundwater wells recorded by the TWDB for each county, but this information is included in each data

availability table as needed (Table 16 and Appendices X through XIV). The total number of groundwater wells

for each county of interest is a count of state well numbers listed in the TWDB “Well Location Shapefile”

(TWDB GISa; TWD B GISb).

P arameters such as those listed in Table 5 can be assessed with statistical principles to determine if the

number of wells that have been sampled is adequate to define reliable mean concentrations for each

parameter in the region. As such, p ower analysis was used for each parameter in each county of interest to

determine the statistical power of the sample size with a pre

- defined effect size (ES) and significance level

( α ) 20

. A larger statistical power indicates greater accuracy ( Cohen 1992 ) , and a power of 0.80 is

recommended 21 . Cohen (1992) uses a calculation that recommends between 26 and 38 samples for a power

of 0.80, allowing a large effect size and α = 0.05 or 0.01 for the difference in means, respectively.

Notably, Caldwell and Guadalupe Counties have the fewest number of samples. Additionally, c ounties with

less than 26 wells that have been sampled ( out of those with reliable samples ) include Gu adalupe, Caldwell,

Madison, Dewitt, McMullen, Washington, Fayette, and Bee. Adding to that list, those counties with fewer

than 38 samples include Goliad, Austin, Karnes, Grimes, Lee, Leon, Houston, and Wood. . Contrastingly, the

counties with the strong est statistical power, containing more than 26 individual water wells that also have

more than one sample attributed to the well are Atascosa, Duval, Frio, Gonzalez, LaSalle, Webb, and Zavala.

A list of each general water chemistry parameter found in the d atabase is provided in Appendix VIII.

Additionally, the TWDB database contains EPA STORET data with concentrations of infrequent constituents.

Over 270 different infrequent constituents are listed in the data base (see Appendix IX). Selected

constituent s are described in forthcoming sections of this analysis, as they relate to detecting contamination

from oil and gas activities.

19 TWDB Groundwater Database available at: http://www.twdb.state.tx.us/groundwater/data/gwdbrpt.asp

20 In this case, ES is zero when th ere is no difference between a given sample and the distribution mean for the

sample size being considered. ES ranges infinitely upward from zero when the residuals are not equal to zero

Cohen (1992). Therefore, a small ES renders a more precise statisti cal value. Additionally, alpha ( α ) refers to the

probability of falsely rejecting the null hypothesis.

21 Cohen (1992) chose the value 0.80 as the optimal power, because a greater power would require an infeasible

sampling effort, and a lower number would increase the chance of a false pr ediction too greatly.19

T ABLE 5 N UMBER OF SAMPLES AVA ILABLE IN THE TWDB GROUNDWATER DATABASE FOR GENERAL W ATER

QUALITY PARAME TERS IN EACH COUNTY OF THE EAGLE FORD SHALE REGION

.

County Records in

database Individual

wells Records

with reliable

sampling

methods Individual wells

with reliable

sampl es Wells with

multiple reliable

samples Youngest

record in

reliable

samples Oldest re cord in

reliable

samples

Atascosa 784 370 182 87 49 2010 1990

Austin 214 104 68 27 16 2009 1992

Bastrop 563 266 84 38 18 2010 1988

Bee 387 243 44 25 11 2009 1990

Brazos 395 222 73 45 18 2010 1992

Burleson 455 297 85 60 16 2011 1992

Caldwell 410 273 26 14 7 2011 1992

Colorado 394 155 108 44 22 2009 1988

Dewitt 357 243 40 17 8 2009 1988

Dimmit 414 198 100 54 24 2010 1990

Duval 452 247 129 75 32 2009 1990

Edwards 166 70 81 42 20 2011 1993

Fayette 615 337 60 24 15 2010 1988

Frio 486 239 143 81 34 2010 1990

Goliad 263 185 42 27 9 2009 1990

Gonzales 588 244 277 68 40 2011 1988

Grimes 292 225 41 30 7 2009 1992

Guadalupe 239 170 18 10 3 2010 1992

Houston 204 95 82 33 21 2010 1993

Karnes 496 356 43 28 10 2009 1988

LaSalle 276 119 85 43 27 2010 19 90

Lavaca 204 115 103 49 17 2009 1992

Lee 257 149 74 32 10 2011 1989

Leon 175 74 75 32 21 2010 1992

Live Oak 212 115 65 39 18 2009 1990

Madison 109 41 38 17 11 2011 1993

Maverick 92 72 66 56 9 2002 1992

McMullen 188 70 48 19 13 2010 1992

Milam 379 192 79 39 19 2010 1988

Robertson 529 352 97 48 22 2011 1989

Washington 324 246 38 22 10 1992 2009

Webb 254 115 127 67 35 2010 1989

Wilson 438 185 100 50 24 2010 1990

Wood 326 203 55 35 13 2010 1989

Zavala 563 230 115 62 31 2011 1988

Totals 10329 555 5 2503 1240 56920



## Geospatial Analysis

Maps depi cting the concentration of selected groundwater quality parameter s at each well site were created

using a graduated color scheme for each concentration range (see Appendix V for procedures used) . It is

possi ble to interpolate water concentrations across the region for spaces where no water quality data was

available. However, this kind of analysis was not attempted because even simple water chemistry

parameters such as total dissolved solids (TDS) exhibited cases of regional heterogeneity across short

distances of the landscape (Appendix XI, Figure 19) . Therefore, a regional interpolation may imply that

concentrations can be predicted, but true concentrations could still vary significantly from the mean. Fo r this

reason, it may also not be reasonable to assume that counties with a quantity of samples exhibiting strong

statistical power are able to predict the concentration of various chemical parameters in their region. This

point serves to encourage additi onal sampling when possible, considering that the mass of samples already

compiled only serves to establish a potential range of concentrations, whereas concentrations that vary

significantly from the mean could occur in any water well.21



## III. Results

The purp ose of characterizing the baseline is to determine which chemical parameters are already well

construed across the landscape , and to identify geographic regions and chemical parameters where testing

efforts should be focused . Earlier, certain counties wer e highlighted as having particularly few groundwater

samples recorded in the TWDB database, while others were highlighted as having a statistically acceptable

number of samples. Although records may exist in the TWDB database for the specified number of w ells, not

every well owner has cond ucted all of the baseline groundwater quality tests that are necessary for

comparison with a potentially contaminated sample

. Therefore, although some counties may seem to have

enough samples recorded in the TWDB databas e, closer inspection may reveal deficiencies in baseline

ground water quality data

.

Additional analysis described below uses the USGS produced waters database and geochemical

concentrations found in the literature for the Eagle Ford shale , to compare concen trations of various

chemical parameters to groundwater chemical concentrations. This analysis helped to determine which

parameters are likely to show changes in groundwater concentrations if an influx of produced water occurs.

As discussed earlier, high levels of uncertainty are embedded in the produced waters dataset, but a broad

comparison of produced water and groundwater is presented in section C, below. More data is needed to

develop an accurate comparison, but the data presented here serve as a use ful guide for future research.



## Testing priority codes

For most of the categories that follow , codes are used to describe whether increasing the number of samples

for a particular parameter should be a high priority each county. The codes used are based on the number of

samples required by power analysis to achieve a power of 0.80, as described in the Groundwater Data

section. For counties with less than 26 samples of a particular parameter, the code “T” is used to

recommend that testing be a high priority . In this situation, a region

- wide testing initiative is strongly

recommended to enhance the baseline dataset. For counties that have between 26 and 38 samples, the

code “R” is used to indicate that testing is recommended. In this situation, testing init iatives are

recommended to enhance the baseline dataset. Finally, for counties that have more than 38 samples, the

code “A” is used to indicate that testing should take place as needed. In this situation, testing initiatives are

no t necessary, but those interested in the water quality of a specific well that has not yet been tested should

understand that the groundwater chemistry of the well could vary significantly from the baseline even if

more than 38 samples exist for a given county ; if financially po ssible, testing is recommended.



### A. Gas Hydrocarbons

Baseline c haracterization

Natural gas is made up mostly of methane (CH

4 ) , but may include hydrocarbon gases such as propane (C 3 H 8 ),

hexane (C 6 H 14 ), and ethane (C 2 H 6 ) ( Union gas 2012 ) . No samples for methane, ethane, propane, or hexane

were available in the Texas Water Development Board groundwater quality database. However, all of these

cases contain organic carbon. Therefore, a test for total organic carbon (TOC) would enc ompass

measurements for these gases in a baseline water quality test.22

O ut of the 35 counties examined

, eight counties have samples for total organic carbon (TOC) , and 13 counties

have samples for 13 C/ 12 C stable isotope ratios. Appendix X, Table 2 3 depic ts the total number of samples of

each of these constituents that are found in the sixteen counties for which samples of these parameters are

available.

Although the total number of samples known to exist in the entire Eagle Ford shale region conforms to the

power analysis guidelines presented by Cohen (1992), a map depicting the sample locations (Figure 9)

indicates that most of the region lacks geographically relevant samples for TOC. More sampl es taken over a

broader geographic region are recommended to help verify whether hydrocarbons are pre

- existing in certain

water wells

.

F IGURE 6 T OTAL ORGANIC CARBON CONCENTRATIONS IN TH E COUNTIES OF INTERE ST

.

Testing for TOC over a broader geographic region is recommended, and would p rovide data necessary for

comparing baseline water samples to those that are potentially contaminated from oil and gas. However,

establishing this dataset will take time , and since heterogeneity in TOC concentrations might exist across the

landscape a rea ding at any one well has a high probability of Type I or II error 22

. Simply put, the dataset is

not yet large enough or well distributed enough to be able to accurately depict when a sample concentration

is a true representation of what is expected. Ther efore, as the dataset for TOC is being established, these

concentrations should be support ed with a carbon isotopic signature. This w ill enable a more accurate

22 Type I and II error indicate that a sample was mistakenly thought to be different or similar, respectively, when

compared the average, when in fact the opposite is true.23

assessment of whether hydrocarbons occurring in a well without background TOC concentrations we re pre

existing or were sourced from a petroleum hydrocarbon

- bearing formation.

Only 35 samples are available in the TWDB Infrequent Constituents database for 13 C/ 12 C stable isotope ratios

in groundwater across the entire Eagle Ford shale region (Appendix X , Table 2 3 ) . However, these samples

were more geographically distributed across the region 23 than the TOC sample sites. Interestingly, the δ 13 C

concentrations found in groundwater for the counties of interest were less negative than δ 13 C concent rations

found in the Eagle Ford shale , indicating that the methane found in these groundwater samples could also be

thermogenic (e.g. sourced from a d eep formation which potentially bears petroleum hydrocarbons) ( Schoell

1980 ; Barker and Fritz 1981 )

.

F IGURE 7 G EOGRAPHIC DISTRIBUTI ON OF CONCENTRATIONS AND SAMPLES OF 13 C/ 12 C STABLE ISOTOPE

RATIOS

.

The range of 13 C/ 12 C stable isotope ratio s in groundwater is between

- 7.2 ‰ and

- 18.1 ‰ ( Appendix X, Table

23 ) 24

. In a single sample t

- test, the mean of 13 C/ 12 C stable isotop e ratios is

- 10.57391, with a p

- value of less

than 0.01, and 95 % confidence intervals of

- 11.687710 and

- 9.462116. These results indicate that regional

variation exists in the 13 C/ 12 C stable isotope ratio of groundwater in the countie s of interest. This result

23 Exploration of the dataset reveals that these samples were taken between the years 2002 and 2009. Some of

the samples that appear in lines across the landscape were taken within the same month, implying a coordinated

sampling effort.

24 A boxplo t shown in Appendix X, Figure 2 0 indicates that the 13 C/ 12 C stable is otope ratio of

- 18.1 ‰ could be an

outlier.24

implies that the probability of Type I or II error is high when comparing groundwater samples to potentially

contaminated samples, and underscores the importance of additional testing.

In order to compare these groundwater sampl es to expected δ 13 C concentrations found in the Eagle Ford

shale formation, a strategic literature search was conducted , and is described in Appendix V

. Out of the

references returned, only two provided values for δ 13 C in the Eagle Ford s hale formation. Kearns (2011)

reports δ 13 C values between a range of

- 24.094 ‰ and

- 26.023 ‰ for five core samples taken in DeWitt

County in the Eagl e Ford Formation, while 40 Eagle Ford samples taken in Gonzales County at varying depths

exhibited a δ 13 C range of

- 27.0 7 ‰ to

- 26.78 ‰

. Additionally, Comet (1993) documents δ 13 C values in whole

oil, postulated to have been sourc ed from the Eagle Ford (Table 6 ) which overlap with the range found by

Kearns (2011). However, the locations of Comet’s 13 C/ 12 C samples are not p rovided. Therefore, it is not

possible to discern whether the samples given represent a range of 13 C/ 12 C ratios relevant to the geographic

scope of this paper.

T ABLE 6 V ALUES OF 13C/12C ISOTOPE RATIOS FOUND IN POTENTIAL E AGLE F ORD S OURCE FORMATIONS

C OMET (1993)

Formation Mean ‰ (range ‰ ) number of samples

Mississippi Delta Oils

- 26.7 (

- 27.9 to

- 25.4) n=50

Louisiana Wilcox

- 26.8 (27.4 to

- 26.2) n=24

Austin Chalk*

- 28.0 (

- 29.1 to

- 25.4) n=29

The carbon isotope values for Dimmit and Guadalupe Counties differ by up to 3 ‰ . When Comet’s data is

included, the difference is up to 5 ‰. These data offer a more well

- defined carbon isotope signature for the

Eagle Ford formation than can be said for groundwater across the landscape , wher e the range is up to 10 ‰

different 25

. O ne reason for the broader range of 13 C/ 12 C isotope ratios in groundwater could be that more

than one aquifer is included in the analysis. To test this hypothesis, 13 C/ 12 C stable isotope ratios were plotted

against depth, but no trend was discovered (see Appendix X, Figure 20 ). The wide distribution of values in

groundwater, and the lack of trend with depth further support the notion that more baseline data is needed

on 13 C/ 12 C isotope ratios

. I n order to assess whe ther C 13 /C 12 stable isotope ratios in produced water of the

Eagle Ford shale have a unique enough signature from those in aquifers of the region, a paired t

- test

comparing core sample C 13 /C 12 stable isotope ratios from Kearns (2011) to groundwater ratios w as

conducted. The t

- test indicates that the mean of differences was 16. 2 ‰ with a p

- value less than 0.01. This

indicates that groundwater C 13 /C 12 stable isotope ratios are distinct enough from C 13 /C 12 stable isotope ratios

values found in the Eagle Ford s hale formation to serve as an indicator of contamination from gas leaks into

aquifers . However, the groundwater samples of 13 C/ 12 C isotope ratios do not represent data from Gonzales

or Dewitt Counties, where the core samples for the Eagle Ford formation w ere taken (see Appendix X I, Figure

1 9 and Table 2 3 ) . Additionally, for 23 counties in the area of interest, no carbon isotope data for

groundwater is available. Considering the limitations of the sample size and the geographic distributions of

25 If the outlier of

- 18.1 ‰ is removed, the range of 13 C/ 12 C stable isotope ratios in groundwater is

- 15.3 ‰ to

- 7.2

‰, with a difference of about 8 ‰.25

data, a ge neral comparison can be made between expected concentrations in the Eagle Ford and the

overlying groundwater aquifers, but the chance of Type I or Type II error remain.



### Health effects

The human health effects of methane are poorly researched. Neither the EPA nor the Agency for Toxic

Substances and Disease Registry list any potential human health effects of methane exposure. However,

methane gas present in high enough concentrations in groundwater could pose an asphyxiation or explosion

hazard if allowed to build up in an enclosed space ( Osborn, Vengosh et al. 2011 )

.



### Cost of testing

Testing for total organic carbon is a much cheaper test than a carbon isotope test (Table 7). Additionally,

relatively few of the labs surveyed conduct carbon isotope testing.

T ABLE 7 C OST OF TESTING FOR C ARBON ISOTOPE RA TIOS AND TOTAL ORGAN IC CARBON WITH LABS

CERTIFIED TO TEST DR INKING WATER IN THE STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost Number of Labs

13 C/ 12 C 133 171 240 3

TOC 25 35 42 7



### Recommendations

Both TOC and 13 C/ 12 C stable isotope ratios sho uld be sampled more thoroughly in groundwater across the

region of the Eagle Ford shale. Additionally, more samples of 13 C/ 12 C stable isotope ratios for hydrocarbons

in the Eagle Ford formation are needed to establish expected regional variation for 13 C/ 1 2 C ratios across the

region. These are important tests to undertake because of the hazards that are posed when water is

contaminated by gas hydrocarbons

.

TOC sampling is a high priority for baseline water quality testing because it can serve as a primary indicator of

potential contamination from petroleum hydrocarbons

, because it is poorly construed across the landscape

for the counties of interest

, and because no one county has enough TOC samples to be considered

statistically powerful. Also, testing for TOC is relatively affordable, so establishing a more robust baseline of

TOC in groundwater across the Eagle Ford shale region is achievable.

That being said, TOC sampling will be ineffective to use as a regional baseline if anomalies in TOC

concentrations exist across the landscape. In order to support TOC concentration findings, more samples of

13 C/ 12 C stable isotope ratios are needed.



### B. Liquid Hydrocarbons

Baseline characterization

Gasoline range organics (GRO) and diesel range organics (DRO) represent l iquid petroleum products that

have a specific number of carbons chained together; C 6 – C 10 , and C 10 – C 28 , respectively ( Environmental

Protection Agency 1999 )

. No samples exist in the TWDB database for either GRO or DRO

. However, a test

for total petroleum hydrocarbons (TPH) would include hydrocarbons in the range of both GRO and DRO. In

the TWDB database, only two s amples exist for the counties of interest

. Those samples were taken in26

D immitt County, and both samples bear the same concentration (see Figure 1 2 ). It is unclear whether the

values provided in the database represent background water quality data or a case of contamination that was

reported through the EPA STORET database 26 ( Rein and Hopkins 2008 )

.

F IGURE 8 G ROUNDWATER C ONCENTRATIONS OF T OTAL P ETROLEUM H YDROCARBONS IN THE C OUNTIES OF

INTEREST

. T WO DATAPOINTS ARE FO UND IN THE DATABASE

, BUT THEIR LOCATIONS OVERLAP ON THE MAP

.



### Health effects

Health effects associa ted with some TPH compounds include headaches and dizziness, numbness in the feet

and legs. Additionally effects on the blood, immune system, lungs, skin, and eyes are known to occur for

some TPH compounds ( Agency for Toxic Substances and Disease Registry 1999 )

.



### Cost of test ing

The cost of testing for TPH is less expensive than testing for both GRO and DRO at the same time (Table 8)

.

The test is moderately expensive, but more labs test for TPH than GRO or DRO.

T ABLE 8 C OST OF TESTING FOR L IQUID HYDROCARBONS W ITH LABS CERTIFIED T O TEST DRINKING WATE R IN

THE STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost N umber of Labs

Diesel Range Organics 68 82 97 3

Gasoline Range Organics 72 84 91 3

26 TPH concentrations were reported in the infrequent const ituents portion of the TWDB groundwater quality

database. Most data in the infrequent constituents database came from the EPA STORET database.27

TPH 50 89 138 4



### Recommendations

Considering these potential health impacts and the lack of current baseline groundwater quality data for

liquid hydrocarbons , it is clear that more background water quality data is needed to determine whether

cases of existing liquid hydrocarbon leaks into groundwater exist in counti es that make up the Eagle Ford

s hale region. Although liquid hydrocarbons are not expected to occur in groun dwater

, additional background

data would aid in preventing false claims that contamination was either present or not present before oil and

g as extraction activities began. Since virtually no baseline groundwater quality data is available for TPH , and

tes ting is relatively expensive, it is recommended that an agency , industry, or other organization take on a

groundwater sampling initiative for TPH that is geographically representative of the Eagle Ford shale region.28



### C. Salts

Relevant parameters in produced water

The concentration of like constituents in groundwater and produced water can be compared in order to

determine whether the mean difference in each is statistically significant. If produced water concentrations

of any particular salt are always much higher than the concentrations in the groundwater, that particular salt

can be considered an effective parameter to use for detecting a change in groundwater chemistry caused by

oil and gas activities

.

In this analysis, Eagle Ford shale formation produced water samples are compared to groundwater samples

for Wood County , for the parameters that are available in the produced waters database . However, given

the uncertainties associated with how closely Wood County data resembles the geochemistry of the Eagle

Ford in the current active drilling area, additional produced water samples from other formations were

compared to groundwater samples to establish a generally applicable range of how greatly produced water

differs from groundwater. These additional prod uced water samples were compiled from only the counties

of interest, and represent all formations that are listed for those counties.

A paired t

- test was used to determine whether the differences in produced water quality of the Eagle Ford

were statistical ly significant when compared to groundwater. First, data for Wood County indicates that all

analyte concentrations were significantly greater in produced water except for pH and sulfate ( Appendix XI,

Table 24 ). Total dissolved solids (TDS), chloride, and sodium return the greatest mean of differences.

Additionally, for all three analytes, the maximum values found in groundwater do not overlap with the

minimum values found in produced water ( Appendix XI, Table 2 5 ).

Although only Wood County data was ava ilable for the Eagle Ford shale in the produced waters database,

produced water chemistry for all the counties of interest was compared to groundwater chemistry for all the

counties

. Slight differences from the Wood County data are observed when these add itional data points are

considered

.

First, pH and sulfate are statistically significant when results for all counties are considered ( Appendix XI,

Table 26 ). Notably, pH in groundwater exhibits a broader range of values than produced water ( Appendix XI,

Table 27 ) , and would be a poor indicator of post

- drill contamination without a baseline water quality test for

the actual well at which potential contamination is experienced. Therefore, a baseline of pH in groundwater

would not be expected to be higher or lower than produced water pH unless both produced water and

baseline groundwater quality for the site were known prior to the potential influx of contaminants to the

aquifer.

Next, data for potassium were not available in the Wood County dataset; where as 143 produced water

samples recorded potassium concentrations for other formations in the counties of inter e st ( Appendix XI,

Table 2 7 ). Nonetheless, potassium concentrations are not likely to be a useful indicator of contamination,

considering that the maximum groundwater concentration of potassium is close to the value of the third

quantile of the potassium concentration for produced water. Also, the maximum concentration of potassium

in produced water is an order of magnitude higher than the third qua ntile, indicating that the dataset may

contain outliers that skew the distribution of potassium concentrations (Appendix XI , Table 27 ).

According to the produced waters data for all counties of interest, sulfate concentrations in produced water

are higher than in groundwater by a statistically significant amount (Appendix XI, Table 26 ). However, the29

range of concentrations in groundwater indicates that the maximum concentration of sulfate in groundwater

is greater than the third quantile in produced water (Appendix XI, Table 2 7 ). Similar to potassium, the high

sulfate concentrations found in the upper quantile of the produced waters may be skewed by outliers.



### Baseline characterization

Only Caldwell and Guadalupe counties have poor statistical power for all of the general water chemistry

parameters that are listed in the produced waters dataset, although testing is recommended for some of

these parameters in Madison (Appendix XI, Figure 27) and Washington (Appendix XI, Figure 28) counties.

Every other count y has strong statistical power based on the number of samples it has.

Other salts that have not yet been discussed, but which were indicated as important in the case studies,

include bromide, nitrate, and selenium. N umber, percent, and groundwater testing recommendations for

these parameters are given in Appendix IX, Figure 29. Power analysis indi cates that most counties have an

acceptable number of samples for bromide and selenium, but many counties need more samples for nitrate

in order to adequately ch aracterize the baseline for these parameters.



### Health effects

A lthough a change in chemistry could occur from an influx of produced water into an aquifer , the

constituents found in the produced waters database are not necessarily harmful. No Maximum Contam inant

Levels (MCL) exist for the chemicals listed in the produced waters database. However, t he EPA has defined

Nati o n al Secondary Drinking Water Standards ( Secondary Standards ) for pH, c hloride, s ulfate, and Total

Dissolved Solids (TDS) (Table 9 ). Alter natively, MCLs are defined for bromate 27 , nitrate, and selenium. The

known health effects of these parameters are listed in Table 9.

T ABLE 9 EPA MCL S AND S ECONDARY S TANDARDS FOR SALTS A ND P H IN GROUNDWATER

( E NVIRONMENTAL P ROTECTION A GENCY 2012 )

.

Chemical MCL (mg/l) Health effects

pH 6.5

– 8.5*

Chlo ride 250*

Sulfate 250*

TDS 500*

Bromate 0.01 Increased risk of cancer

Nitrate 10 Infants below the age of six months who drink water containing nitrate in

excess of the MCL could become seriously ill and, if untreated, may die.

Symptoms include shor tness of breath and blue

- baby syndrome.

Selenium 0.05 Hair or fingernail loss; numbness in fingers or toes; circulatory problems

*EPA Secondary Standard for drinking water

27 Bromate is a common byproduct of bromide interactions with disinfectants in surface water. Source: New York

State Department of Health. (2011, April 2011). "Bromate in Drinking Water

- Information Fact Sheet." Drinking

Water Protection Program

.30



### Cost of testing

Magnesium, potassium, and bromide are the most expensive paramete rs to test out of the salt category.

However, on average, salts are less expensive to test than other parameters. There are also a greater

number of laboratories that test salts than there are that test some of the other parameters discussed in this

anal ysis (Table 10)

.

T ABLE 10 C OST OF TESTING

, IN USD, FOR VARIOUS SALTS WI TH LABS CERTIFIED TO TEST DRINKING WATER

IN THE STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost Number of Labs

Bromide 13 30 60 7

Calcium 9 11 15 3

Chloride 13 22 43 7

Magnesium 9 35 60 2

Nitrate 13 22 43 9

Potassium 9 35 60 2

Selenium 10 17 20 5

Sodium 9 11 15 3

Sulfate 13 23 58 11

TDS 12 21 33 11



### Recommendations

If contamination does occur, the baseline for TDS, chlorides, and sodium has al ready established across most

of the Eagle Ford shale region 28 , and concentrations in groundwater as high as what would be found in

produced water would imply contamination in a post

- drilling test. Therefore, rather than spend limited

resources to test all of the potential analytes in the produced waters database, only the produced water

parameters that deviate substantially from the mean found in groundwater should be a high priority for

testing . Also, considering that there is no secondary standard liste d for sodium, TDS and chloride should take

higher priority than sodium in a list of analytes for baseline ground water quality testing. Likewise,

parameters such as bromide, selenium, and nitrate should be a high priority for testing in counties where

poor statistical power is available. Considering that the cost of testing these parameters is relatively low, and

that the baseline is partially established in all counties of the Eagle Ford shale region, testing for salts could

feasibly be taken on by water well owners.

28 Locations of where TDS, chlorides, and sodium have been tested are depicted in Appendix XI, Figure 19.31



### D. Metals

Baseline characterization

Every case study mentioned in this analysis considers trace metals in either baseline ground water quality

testing or in testing for potential post

- drill contamination. Concentrations of trace metals in produ ced waters

of the Eagle Ford shale formation were either not found in the literature, or did not represent enough

samples to warrant a comparison with groundwater concentrations. Therefore, it is unclear how necessary

trace metal samples are to background water quality testing in the Eagle Ford shale region in particular.

Nonetheless, a list of trace metals was compiled from the case studies discussed in the introduction. With

the exception of phosphorus

, for each trace metal identified every county has at least one sample 29 . The

number of samples varies by county and parameter, but testing recommendations based on power analysis

can be found for each parameter and county in Appendix II, Tables 36 to 42

.



### Health effects

Table 1 1 lists the potential health effects of metals, metalloids, and additional salts that are known to occur

in oil and gas flowback fluids. No MCL or health effects were listed for Boron, Cobalt, Molybdenum, Nickel,

Phosphorus, Silicon, or Strontium.

T ABLE 11 EP A M AXIMUM C ONTAMINANT L EVELS (MCL) AND S ECONDARY S TANDARDS FOR METALS IN

DRINKING WATER AND A SSOCIATED HEALTH EFF ECTS

.

Element MCL (mg/l) Health effects

Aluminum *0.05 to

0.2

Antimony 0.006 Increase in blood cholesterol; decrease in blood sugar

Arsen ic 0.01 Skin damage or problems with circulatory systems, and may have

increased risk of getting cancer

Barium 2 Increase in blood pressure

Beryllium 0.004 Intestinal lesions

Cadmium 0.005 Kidney damage

Chromium 0.1 Allergic dermatitis

Copper 1

Iron *0.3 mg/L

Lead 0.015 Infants and children: Delays in physical or mental development; children

could show slight deficits in attention span and learning abilities; Adults:

Kidney problems; high blood pressure

Manganese 0.05*

Mercury 0.002 Ki dney damage

Selenium 0.05 Hair or fingernail loss; numbness in fingers or toes; circulatory problems

Silver *0.10 mg/L

*EPA Secondary Standard

29 Silicon was not included in the database.32



### Cost of testing

Testing metals is generally not expensive (Table 12) . Additionally, ma ny metals can be tested together in a

batch, making the cost of testing multiple parameters more affordable.

T ABLE 12 C OST OF TESTING

, IN USD, FOR METALS WITH LABS CERTIFIED TO TEST DR INKING WATER IN THE

STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost Number of Labs

Metals package 175 175 175 1

Metals single 10 20 35 5



### Recommendations

More data is needed on the concentrations of trace metals that are expected to be found in produced water

of the Eagle Ford shale region. Without this information, defining a narrow list of baseline groundwater

testing for metals is difficult. Although the baseline is well characterized for some metals, the dataset is less

robust for others. When it comes to metals, baseline testing must be considered on a county

- by

- county basis

for each parameter. At a minimum, it is safe to say that metals which are known to cause health effects

should be considered as a higher testing priority than other metals.



### E. Naturally

- Occurring Radioactive Materia ls (NORM)

Baseline characterization

Various kinds of radionuclides are known to occur naturally in oil and gas formations including uranium

- 238,

uranium

- 235, thorium

- 232, and their daughter products: radium

- 226, radium

- 228, lead

- 210, and polonium

210 ( NORSEDECOM 2003 ) 30 . Generally, the concentrations of radionuclides found in produced water are not

expected to be very high, but waste handling methods can lead to higher concentrations of long

- living

radionuclides being stored at the surface ( Valeur and Ramboll Oil and Gas 2010 )

.

In the Eagle Ford shale formation, very high in

- situ gamma radiation from potassium

- 40, thorium , and

uranium have been observed ( Fertl 1979 ) . At the surface however, the RRC reports that one Eagle Ford

drilling field in Wood County documented radiation greater than 500 microroentgen/hour ( μ R/hr) 31 ( Railroad

Commission of Texas 2000 ) . Aside from the case in Wood County, groundwater contamination from

uranium and radon

- 226 has been documented in Live Oak, Karnes, and Gonzales Counties ( Wukasch and

Cook 1971 or later ; McConnell, Ramanujam et al. 1998 ) . These cases of contamination are related to

historical uranium mining and wast e disposal, activities which have also taken place in Duval, Karnes, Webb,

Live Oak, Bee, and Fayette Counties ( Pirson 1970 ; Annamalai and McGarvey 1980 ; Fishman and Huang 1980 ;

Jones 1981 ; Otto Jr. 1984 ; McConnell, Ramanujam et al. 1997 ) . The possibility of encountering historical

radionuclide contamination underscores the importance of baseline testing for radioactive elements or

30 Cited in Valeur (2010)

31 According to the RRC website, a microroentgen is a measurement of exposure to x

- ray or gamm a ray radiation in

the air, whereas picocuries (pCi) measure the amount of a substance that decays over time RRC (2000). 500 μ R/hr

is one order of magnitude greater than the regulatory standard (50 μ R/hr) for release of materials for uses other

than oil a nd gas activities.33

particle emissions in t he Eagle Ford shale region to avoid false assumptions about the presence or absence of

radioactive materials before oil and gas drilling begins.

Knowing which parameters are the most important ones to test for, however, is more complicated. Out of

the rad ionuclides discussed here, radium

- 226 and

- 228 are the most common, and the most long lived ( Fertl

1979 ; Lawrie, De smond et al. 2000 ; Valeur and Ramboll Oil and Gas 2010 ) . Given this evidence, it at first

seems appropriate to focus baseline water quality testing on radium

- 226 and radium

- 228; however, given the

fac t that potassium, thorium, and uranium are known to exist in high concentrations in the Eagle Ford

formation, only testing for radium would be insufficient

.

Yet, testing for all of these parameters is not necessary, because radionuclides each give off a certain kind of

radiation that is sometimes the same for other radionuclides, and the number of baseline analytical tests can

be significantly reduced if only the appropriate kinds of radiation are tested. Three kinds of radioactive

emissions exist: alpha , beta, and gamma radiation. All of the radionuclides discussed give off alpha or beta

particle emissions, except for potassium

- 40 which emits gamma radiation (Table 1 3 )

.

T ABLE 13 T YPES OF RADIOACTIVE EMISSIONS KNOWN TO O CCUR FROM VARIOUS

RADIONUCLIDES ( F ERTL 1979 )

Radionuclide Type of emission

Uranium

- 238 Alpha

Thorium

- 232 Alpha

Radium

- 226 Alpha

Radium

- 228 Beta

Radon

- 222 Alpha

Potassium

- 40 Gamma

Lead

- 210 Beta

Polonium

- 210 Alpha

The numbers of wells with reliable samples that have tested radionuclides in the counties of interest are

listed in Appendix XIII , Table 43 . Radium

- 226 and Radium

- 228 have been tested in most counties, but rad on,

thorium and potassium

- 40 have been tested in fewer than 10 counties. Additionally, lead

- 210, polonium

210, and gamma radiation are not recorded anywhere in the database.

Every county has tested for a lpha or b eta radiation (Appendix XIII, Table 34 ). However, most of the counties

have poor statistical power due to the low number of samples that have been reported, and additional

sampling is needed. Additionally, some records indicate concentrations that are greater than the EPA MCL

(see Figure 15). It is unclear whether these data points were taken in response to a case of contamination, or

whether they represent unaffected background data.3 4



### Health effects

Although alpha and beta particles are the most easily shielded from skin contact, ingestion o f alpha and beta

particles is known to carry greater risk than external exposure to these particles ( Smith and Argonne National

Laboratory 1992 ) . Gamma radiation, however, is able to penetrate through thick protective layers, and is

generally considered to be the most harmful ( Environmental Protection Agency 2012 )

. The EPA lists MCLs for

uranium, radium, alpha particles, and beta particles, and all are associated with an increased risk of cancer

( Table 1 4 ) ( Environmental Protection Agency 2012 ) . Potassium

- 40 and thorium are also known to cause

cancer ( Argonne National Laboratory 2005 ; Environmental Protection Agency 2012 ) , but are not regulated in

drinking water.

T ABLE 14 EPA M AXIMUM C ONTAMINANT L EVELS FOR RADIOACTIV E ELEMENTS / PARTICLES IN DRINKIN G

WA TER

Radioactive element MCL

Uranium 30 μ g/l

Radium 5 pCi/l

Alpha particles 15 pCi/l

Beta particles 4 millirems/year

F IGURE 9 A LPHA PARTICLE CONCEN TRATIONS IN THE COUN TIES OF INTEREST

. R ED POINTS REPRESENT

VALUES GREATER THAN THE EPA MCL.35



### Cost of testing

On average, the cost of testing alpha and beta particle emissions together is less expensive than testing these

parameters separately. Additionally, it is clear that testing for specific radionuclides is much more expensiv e.

Similarly, testing gamma emissions is less expensive than testing for potassium

- 40, the only gamma radiation

emitter on the list.

T ABLE 15 C OST OF TESTING

, IN USD, FOR R ADIONUCLIDES WITH LA BS CERTIFIED TO TEST DRINKING

WATER IN THE STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost Number of Labs

Alpha 16 37 50 3

Alpha/Beta 50 54 65 4

Beta 16 37 50 3

Gamma 84 84 84 1

Potassium

- 40 250 250 250 1

Radium 226 65 92 125 4

Radium 226 and 228 150 168 185 4

Radium 228 85 1 02 125 4

Radon 222 35 96 200 4

Uranium 20 107 255 8



### Recommendations

C onsidering the health effects associated with radionuclides , regional heterogeneity of alpha concentrations

(Figure 13) , and the low statistical power of the available sample sizes mo re testing is recommended. Testing

for alpha, beta, and gamma radiation is recommended, since these parameters encompass the effects of

multiple radionuclides, and because these tests cost less than test for individual radionuclides.



### F. Volatile Organic Com pounds (VOCs)

The volatile organic compounds (VOCs) most commonly associated with oil and gas are the BTEX chemicals:

benzene, toluene, ethylbenzene, and xylene. These chemicals are not generally thought to occur in

groundwater, but determining backgroun d concentrations is necessary to verify this speculation. A

comprehensive national study seeking to determine baseline concentrations of VOCs in groundwater found

toluene in at least 1 % of samples, although concentrations greater than the MCL were not fo und ( Wukasch

and Cook 1971 or later ) . The study area, however, did not include samples within counties of the Eagle Ford

shale region , and e thylbe nzene and xylene were not considered in the research

.



### Baseline characterization

For this analysis, c oncentrations of BTEX chemicals are only provided for six counties in the TWDB

groundwater quality database. All counties have less than 26 samples, indic ating insufficient statistical power

(Table 16 )

. Additionally, geospatial analysis indicates that the available samples are not evenly spaced36

enough to establish a reliable baseline across the region (Figure 1 3 ) , and some samples exceeded the MCL

.

In th ree counties, no samples were take n for xylene; whereas benzene, e thylbenzene, and toluene were

tested at the same time in all the other samples

. It is unclear whether these samples were taken in response

to a case of potential contamination, or if they w ere intended to repr esent baseline ground water quality.

T ABLE 16 N UMBER AND PERCENT OF WELLS WITH RELIABLE SAMPLES FOR WHICH CO NCENTRATIONS OF

BTEX CHEMICALS ARE FOUND IN THE TWDB GROUNDWATER DATABASE

.

F IGURE 10 B ENZENE CONCENTRATION S IN THE COUNTIES OF INTEREST

. P OINTS MARKED IN RED INDICATE

CONCENTRATIONS THAT EXC EED THE EPA MCL FOR BENZENE

. County Total

wells Benzene Ethylbenzene Toluene Xylene

Bastrop 791 3 0.4% 3 0.4% 3 0.4% NA

Colorado 574 1 0.2% 1 0.2% 1 0.2% NA

Dimmit 527 24 4.6% 24 4.6% 24 4.6% 24 4.6%

Fayette 863 4 0.5% 4 0.5% 4 0.5% NA

La Salle 362 4 1.1% 4 1.1% 4 1.1% 4 1.1%

Zavala 748 3 0.4% 3 0.4% 3 0.4% 3 0.4%

Grand Total 3865 39 1.0% 39 1.0% 39 1.0% 31 0.8%37



### Health effects

All four VOCs listed here are regulated by the EPA in drinking water. All of the BTEX chemicals are considered

to present serious health effects (Table 21)

.

T ABLE 17 H EALTH EFFECTS O F VOLATILE ORGANIC C OMPOUNDS COMMONLY FO UND IN OIL AND GAS

FLOWBACK ( E NV IRONMENTAL P ROTECTION A GENCY 2012 )

.

Chemical

parameter MCL (mg/l) Health Effects

Benzene 0.005 Anemia; decrease in blood platelets;

increased risk of cancer

Toluene 1 Nervous system, kidney, or liver problems

Ethylbenzene 0.7 Liver or kidneys problems

Xylene 10 Nervous system damage



### Cost of testing

The cost of testing BTEX chemicals is high Table 18) . This cost is conceivably not affordable for some water

well owners.

T ABLE 18 C OST OF TESTING

, IN USD, FOR VOC WITH LABS CERTI FIED TO TEST DRINKIN G WATER IN THE

STATE OF T EXAS

.

Test Min of Cost Mean of Cost Max of Cost Count of Lab

BTEX 40 87 125 5

VOC 50 149 200 8



### Recommendations

Considering the potential health impacts of BTEX chemicals, the fact that they are frequently li sted as

contaminants from oil and gas activities in the counties of inter e st, that they could occur naturally, and

because so few samples have been taken across the landscape it is highly recommended that a strategic

baseline groundwater sampling initiativ e for VOC, including BTEX, take place by an agency , industry, or other

organization.



### G. Polycyclic Aromatic Hydrocarbons (PAHs)

Baseline characterization

PAHs are known to occur in oil and gas flowback water ( Bojes, Pope et al. 2007 ; Joa, Panova et al. 2009 )

. All

counties of interest have tested PAHs fewer than 26 times, indicating poor statistical power ( Appendix XIV,

Table 4 5 ) . Geospatial analysis indicates wide geographical gaps in sampling (Figure 1 4 ). All of these tests

were taken at the same time, and seven of the 49 samples exceeded the EPA MCL for benzo(a)pyrene (Tables

25 and 26) . Therefore, it is unclear whe ther these samples represent background concentrations or if they

were taken in response to potential contamination.38



### Health effects

Animal testing has shown that PAHs cause reproductive and developmental health effects. Additionally,

detrimental effects to the skin, body fluids, and immune system have been observed in animals ( Agency for

Toxic Substances a nd Disease Registry 1996 ) . The EPA has listed 16 priority

- pollutant PAHs ( Appendix 14,

Table 45 ), but o nly Benzo(a)pyrene is regulated in drinking water ( Bojes, Po pe et al. 2007 ; Joa, Panova et al.

2009 ; Environmental Protection Agency 2012 ) . Seven of the 16 priority

- pollutant PAHs have been listed as

probable carcinogens by the EPA ( NTP 2005 ) 32 . Points marked in red in Figure 1 4 exceed the EPA MCL of 10

μg/l of Benzo(a)pyrene.

F IGURE 11 B ENZO ( A ) PYRENE CONCENTRATION S IN THE COUNTIES OF INTEREST

.



### Cost of testing

All 16 priority PAH c an be tested at the same time in a p ackage. In fact, laboratories do not offer individual

tests of these parameters. Nonetheless, the cost of testing for PAH is expensive, and may be unaffordable to

some well owners.

T ABLE 19 C OST OF TESTING

, IN USD, FOR PAH WITH LABS CERTIFIED TO TEST DRINKING WAT ER IN THE

STATE OF T EXAS

.

Test Min of Cost Average of Cost Max of Cost Number of Lab s

PAH 120 148 176 2

32 Cited in Bojes, H. K., P. G. Pope, et al. (2007). "Characterization of EPA’s 16 priority pollutant polycyclic aromatic

hydrocarbons (PAHs) in tank bottom solids and associated contaminated soils at oil exploration and production

sites in Texas." Regulatory Toxicology and Pharmacology 47 (3): 288

- 295.39



### Recommendations

Considering the serious health effects associated with PAHs, thei r association with oil and gas flowback, and

the lack of available data in the Eagle Ford shale region, a strategic sampling effort for PAHs is recommended

for the counties of interest. Because the cost of testing is so high, such an initiative might best be taken on

by an agency , industry or other organization.40



## IV. Discussion

This analysis employed five different strategies to determine which parameters should be tested prior to oil

and gas drilling to establish a functional baseline for comparison to potent ially contaminated samples. First,

a list of potential parameters was defined using prominent case studies of oil and gas contamination cases.

Second, known concentrations of parameters found in produced water were compared to known

concentrations of tho se same parameters for the same geographic region, in order to determine if

differences could reasonably be expected. Third, statistical power analysis was used to determine whether

the minimum number of samples needed to establish confidence in a range o f concentrations for any given

parameter had already been acquired for each county and parameter of interest . Next, health effects were

considered to highlight potential pollutants that should be prioritized in a sampling initiative. Finally, cost of

tes ting was considered to introduce a perspective about whether a well owner might be expected to

voluntarily participate in baseline ground water quality sampling, or whether an organized and geographically

strategic sampling initiative should be led by an ag ency, industry, or other organization.

The results of employing these strategies reveal that some of the most dangerous chemicals are not

adequately characterized in baseline water quality, if at all. These high priority baseline tests include TOC,

13 C/ 12 C, TPH, nitrate, alpha particles , beta particles , gamma radiation, VOC, and PAH

. The average cost of

testing all of these parameters is approximately $1000.

Contrastingly, with the exception of Caldwell and Guadalupe counties, most salts are well charact erized

across the region. In counties where more tests are needed, TDS, chlorides, bromide, nitrate, and selenium

are the most essential testing parameters. On average, the cost of testing all of these parameters would

total less than $250.

For the most part, metals are also well characterized, but each county has a slightly different number of tests

for each parameter, indicating that testing initiatives for metals will be more localized and tailored to each

county than testing for high priority baseline parameters mentioned above. Another aspect of metals is that

some of the metals analyzed are regulated in drinking water, because of health effects that are associated

with their presence at or above threshold concentrations. For counties and well owner s faced with many

baseline water quality needs, these regulated metals are higher priority parameters than other metals or

salts. The cost of testing these 14 metals listed in table 12 would be about $300 if the average price is true,

or it could be $140 if the lowest price is true ; in which case, the package price would be more expensive.

Counties seeking to enhance current baseline datasets can use the testing priority codes listed in Appendix XII

to determine which metals need to be tested the most in that particular county.

In conclusion, background water quality data is an essential component of assessing potential groundwater

pollution. Considering that cases of potential groundwater contamination linked to oil and gas activities have

been contenti ous due to lack of background water quality data, groundwater stakeholders in the newly and

rapidly developing Eagle Ford shale region would be wise to quickly establish regional initiatives to conduct

baseline water quality testing for the parameters reco mmended here.41



## References

(2011). An ACT relating to the disclosure of the composition of hydraulic fracturing fluids used in

hydraulic fracturing treatments. Chapter 91, Natural Resources Code, Subchapter S

. Agency for Toxic Substances and Disease Registry (1996). Polycyclic Aromatic Hydrocarbons (PAHs)

ToxFAQs. U. S. D epartment of Health and Human Services.

Agency for Toxic Substances and Disease Registry (1999). Total Petroleum Hydrocarbons (TPH).

Annamalai, V. and F. X. McGarvey (198 0). Operating experience in the recovery of uranium at the

Pawnee and Zamzow sites. SPE Annual Technical Conference and Exhibition . Dallas, Texas, 1980

Copyright 1980, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

Argonne Natio nal Laboratory (2005). Potassium

- 40 Human Health Fact Sheet.

Barker, J. F. and P. Fritz (1981). "The occurrence and origin of methane in some groundwater flow

systems." Canadian Journal of Earth Sciences 18 : 1802

- 1816.

Bojes, H. K., P. G. Pope, et al. (2 007). "Characterization of EPA’s 16 priority pollutant polycyclic aromatic

hydrocarbons (PAHs) in tank bottom solids and associated contaminated soils at oil exploration

and production sites in Texas." Regulatory Toxicology and Pharmacology 47 (3): 288

- 295.

Breit, G. N., C. Skinner, et al. (2006). Produced Waters Database, U.S. Department of the Interior,

Central Energy Data Management.

Cohen, J. (1992). "A Power Primer." Quantitative Methods in Psychology 112 (1): 155

- 159.

Colborn, T., C. Kwiatkowski, et a l. (2011). "Natural Gas Operations from a Public Health Perspective."

International Journal of Human and Ecological Risk Assessment

. Comet, P. A., J. K. Rafalska, et al. (1993). "Sterane and triterpane patterns as diagnostic

- tools in the

mapping of oils, c ondensates and source rocks of the Gulf

- of

- Mexico region." Organic

Geochemistry 20 (8): 1265

- 1296.

Condon, S. M. and T. S. Dyman (2006). 2003 Geologic Assessment of Undiscovered Conventional Oil and

Gas Resources in the Upper Cretaceous Navarro and Taylor G roups, Western Gulf Province,

Texas. U.S. Geological Survey Digital Data Series

. Chapter 2

. Dukes, R. T., K. DuBose, et al. (2012). "Eagle Ford Shale Counties." Eagle Ford Shale News, Marketplace,

Jobs Retrieved February 26, 2012, from www.EagleFordShale.com

. Environmental Protection Agency (1999). Total petroleum hydrocarbons (TPH) as Gasoline and Diesel.

12/07/1999

. Environmental Protection Agency (2010). Emergency Administrative Order: Range Resources

Corpor ation and Range Production Company. R. VI. Docket Number: SDWA

- 06

- 2011

- 1208

. Environmental Protection Agency (2011). Investigation of Ground Water Contamination near Pavillion,

Wyoming. Ada, Oklahoma.

Environmental Protection Agency. (2012, January 26, 201 2). "Basic Information about Benzene in

Drinking Water." Water: Basic Information about Regulated Drinking Water Contaminants

Retrieved February 26, 2012, from

http://water .epa.gov/drink/contaminants/basicinformation/benzene.cfm

. Environmental Protection Agency. (2012, January 30, 2012). "Basic Information about Toluene in

Drinking Water." Water: Basic Information about Regulated Drinking Water Contaminants

Retrieved Febru ary 26, 2012, from

http://water.epa.gov/drink/contaminants/basicinformation/toluene.cfm

. Environmental Protection Agency. (2012, January 10, 2012). "Gamma Rays." Radiation Protection

Retrieved April 27, 2012, 2012, from http://epa.gov/rpdweb00/understand/gamma.html

.42

Environmental Protection Agency. (2012, March 6, 2012). "List of Contaminants & their MCLs." Drin king

Water Contaminants Retrieved March 13, 2012, 2012, from

http://water.epa.gov/drink/contaminants/index.cfm

. Environmental Protection Agency. (2012, March 6, 2012). "Thorium." Radiation Protection Retrieved

April 19, 2012, from http://www.epa.gov/radiation/radionuclides/thorium.html#healtheffects

. Farquhar, G. D., M. H. O'Leary, et al. (1982). "On the Relationship between Carbon Isotope

Discrimination and the Intercellular Carbon Dioxide Concentration in Leaves." Australian Journal

of Plant Physiology 9 (2): 121

- 137.

Fertl, W. H. (1979). "Gamma Ray Spectral Data Assists In Complex Formation Evaluatio n." The Log

Analyst (5).

Fishman, P. H. and W. H. Huang (1980). Mineralogical analysis and uranium distribution of the

sedimentary

- type uranium ores. SPE Annual Technical Conference and Exhibition . Dallas, Texas,

1980 Copyright 1980, American Institute of M ining, Metallurgical, and Petroleum Engineers, Inc.

Petroleum Engineers, Inc.

Holbrook, P. (1985). "The Effect of Mud Filtrate Invasion on the EWR Log

- A Case History." SPWLA

Twenty

- Sixth Annual Logging Symposium

. Hsu, S. C. and P. P. Nelson (2002). "Char acterization of Eagle Ford Shale." Engineering Geology 67 (1

- 2):

169

- 183.

Hughes, J. D. (2011). Will Natural Gas Fuel America in the 21st Century, Post Carbon Institute.

Joa, K., E. Panova, et al. (2009). "Determination of polycyclic aromatic hydrocarbons ( pahs) in oil shale

processing wastes: current practice and new trends." Oil Shale 26 (1): 59

- 72.

Jones, T. A. (1981). Deep Well Disposal of In

- Situ Uranium Wastewater in the Southern Duval Mineral

District. SPE Annual Technical Conference and Exhibition . Sa n Antonio, Texas, 1981 Copyright

1981, Society of Petroleum Engineers of AIME.

Kearns, T. J. (2011). Chemostratigraphy of the Eagle Ford formation . Master of Science in Geology, The

University of Texas at Arlington.

Lai, J. (1997). Mechanical behavior of E agle Ford Shale . Doctor of Philosophy, University of Texas at

Austin.

Lawrie, W. C., J. A. Desmond, et al. (2000). "Determination of radium

- 226 in environmental and personal

monitoring samples." Applied Radiation and Isotopes 53 : 133

- 137.

Leusch, F. and M. Bartkow (2010). A short primer on benzene, toluene, ethylbenzene and xylenes (BTEX)

in the environment and in hydraulic fracturing fluids. G. University and S. W. R. Centre.

Lippman Consulting and U.S. Energy Information Administration (2010). Over the la st decade, U.S. shale

gas production has increased 14

- fold and now comprises about 22 percent of total U.S.

production. R. Newell.

McConnell, M. A., V. M. S. Ramanujam, et al. (1997). "Assessment of uranium exposure in a community

near former uranium minin g and milling." Environmental and Molecular Mutagenesis 29 (SUPPL.

28): 34.

McConnell, M. A., V. M. S. Ramanujam, et al. (1998). "Distribution of uranium

- 238 in environmental

samples from a residential area impacted by mining and milling activities." Enviro nmental

Toxicology and Chemistry 17 (5): 841

- 850.

Molofsky, L. J., J. A. Connor, et al. (2011). Methane in Pennsylvania water wells unrelated to Marcellus

shale fracturing. Oil & Gas Journal . Tulsa, United States, Tulsa, PennWell Corporation. 109: 54

-

56,58

- 60,62

- 67,93.

Mullen, J. (2010). Petrophysical Characterization of the Eagle Ford Shale in South Texas. Canadian

Unconventional Resources and International Petroleum Conference, Calgary, Alberta, Canada

, Society of Petroleum Engineers.43

Mullen, J., J. C. Low ry, et al. (2010). Lessons Learned Developing the Eagle Ford Shale. SPE Tight Gas

Completions Conference . San Antonio, Texas, USA, Society of Petroleum Engineers. SPE 138446

. Neff, J., T. C. Sauer, et al. (2011). Bioaccumulation of Hydrocarbons from Produc ed Water Discharged to

Offshore Waters of the US Gulf of Mexico. Produced Water Environmental Risks and Advances in

Mitigation Technologies . K. Lee and J. Neff, Springer Science + Business Media, LLC.

New York State Department of Health. (2011, April 2011) . "Bromate in Drinking Water

- Information Fact

Sheet." Drinking Water Protection Program

. NORSEDECOM (2003). Naturlige radionuklider i det marine miljo

- en oversikt over eksisterende

kunnskap med vekt pa Nordsjo

- omradet. E. Stralberg, A. T. S. Varskog, A . Raaum and P. Varskog.

NTP, N. T. P. (2005). Report on Carcinogens. P. H. Service. Washington, DC, US Department of Health and

Human Services.

Office of Research and Development (2011). Plan to Study the Potential Impacts of Hydraulic Fracturing

on Drinki ng Water Resources Environmental Protection Agency. EPA/600/R

- 11/122

. Osborn, S. G., A. Vengosh, et al. (2011). "Methane contamination of drinking water accompanying gas

well drilling and hydraulic fracturing." Proceedings of the National Academy of Scienc es 108 (20):

8172

- 8176.

Otto Jr., J. B. (1984). "Enhancement of Uranium Loading on Ion Exchange Resin From Carbonate

Leachate Lowering pH From 8 to 6.5." SPE Journal of Petroleum Technology (06).

Pirson, S. J. (1970). "Environmental Logging And Mapping In Th e Search For Minerals." The Log Analyst

. Railroad Commission of Texas. (2000). "NORM

– Naturally Occurring Radioactive Material." Retrieved

April 19, 2012, from http://www.rrc. state.tx.us/environmental/publications/norm.php

. Railroad Commission of Texas. (2012, February 17, 2012). "Eagle Ford Information." Retrieved February

26, 2012, from http://www. rrc.state.tx.us/eagleford/index.php#counties

. Railroad Commission of Texas (2012). February 7, 2012 Letter to Administrator Jackson Re: EPA Draft

Report on Ground Water Contamination near Pavillion, WY Docket ID No. EPA

- HQ

- ORD

- 2011

-

0895. Austin, TX.

Rein, H. and J. Hopkins (2008). Explanation of the Groundwater Database and Data Entry. User Manual

50

. Schlumberger. (2012). "Oilfield Glossary." Retrieved April 24, 2012, from

http://www.glossary.oilfield. slb.com

. Schoell, M. (1980). "The hydrogen and carbon isotopic composition of methane from natural gases of

various origins." Geochimica et Cosmochimica Acta 44 (5): 649

- 661.

Slater, C., T. Preston, et al. (2001). "Stable isotopes and the international sys tem of units." Rapid

Communications in Mass Spectrometry 15 : 1270

- 1273.

Smith, K. P. and Argonne National Laboratory (1992). An Overview of Naturally Occurring Radioactive

Materials (NORM) in the Petroleum Industry. Argonne, Illinois, United States Departm ent of

Energy.

Smitherman, B. T. and D. Porter (2012) "Railroad Commissioners: “EPA’s Vacate Order in Range Case

Confirms Railroad

Commission Findings Based on Scientific Evidence”." News Release

. Sumi, L. (2005). Our Drinking Water at Risk. Durango, CO, O il and Gas Accountability Project,.

Texas Administrative Code (2006). Applicability: Groundwater Contamination Report General Provisions

Relating to Public Files and Joint Report. Section 601.2

. Texas Groundwater Protection Committee (2011). Joint Groundwa ter Monitoring and Contamination

Report

– 2010 Austin, Texas, Texas Commission on Environmental Quality.

U. S. Geological Survey. "Eagle Ford Formation and Woodbine Formations, undivided." Mineral

Resources On

- Line Spatial Data Retrieved March 25, 2012.44

U .S. Energy Information Administration (2010). Eagle Ford Shale Play, Western Gulf Basin, South Texas.

U.S. Energy Information Administration (2011). Trends in Eagle Ford drilling highlight the search for oil

and natural gas liquids. Today in Energy

.

U.S. E nergy Information Administration (2012). Five states accounted for about 56% of total U.S. crude

oil production in 2011.

- . Annual crude oil production. Online, U.S. Department of Energy.

U.S. General Accounting Office (1989). Drinking Water: Safeguards ar e not Preventing Contamination

from Injected Oil and Gas Wastes.

U.S. Geological Survey (2002). Detailed Ascii Field Description.

Union gas. (2012). "Chemical Composition of Natural Gas." About Natural Gas , from

http://www.uniongas.com/aboutus/aboutng/composition.asp

. Valeur, J. R. and Ramboll Oil and Gas (2010). Environmental Impacts of Different NORM Disposal

Methods. SPE Middle East Health, Safety, Security, and Environment Conferenc e and Exhimition

. Manama, Bahrain, Society of Petroleum Engineers.

Wilson, S., L. Sumi, et al. (2011). Natural Gas Flowback: How the Texas Natural Gas Boom Afects Health

and Safety. W. Subra, Texas Oil and Gas Accountability Project

Earthworks Action.

Wuka sch, M. C. and L. M. Cook (1971 or later). High Radioactivity in Drinking Water and Ground Water

in South Texas.45



## Appendix I

– Counties

The data used in this analysis represents all Eagle Ford shale counties listed by three sources: Railroad

Commission [R], Energy Information Administration [E], and the website EagleFordShale.com [S].

 Atascosa [R, E, S]

 Colorado [S]

 Goliad [E, S]

 Lavaca [R, E, S]

 Milam [R, E, S]

 Austin [E, S]

 Dewitt [R, E, S]

 Gonzales [R, E, S]

 Lee [R, E, S]

 Robertson [S]

 Bastrop [E , S]

 Dimmit [R, E, S]

 Grimes [R, E, S]

 Leon [R, S]

 Washington [E, S]

 Bee [R, E, S]

 Duval [E, S]

 Guadalupe [R]

 Live Oak [R, E, S]

 Webb [R, E, S]

 Brazos [E, S]

 Edwards [R]

 Houston *

 Madison [S]

 Wilson [R, E]

 Burleson [R, E, S]

 Fayette [E, S]

 Karnes [R, E, S]

 Maverick [R, E, S]

 Wood *

 Caldwell [R]

 Frio [R, E, S]

 LaSalle [R, E, S]

 McMullen [R, E, S]

 Zavala [R, E, S]

* Houston and Wood Counties were mentioned in EagleFordShale.com as having been listed by t he RRC in a list of Eagle Ford s hale counties.

Alt hough they are no longer listed on the RRC’s webpage for th e Eagle Ford s hale, there is reason to suggest that Eagle Ford drilling is not

entirely ruled out for Houston and Wood counties.

The Railroad Commission of Texas (RRC) reports that drilling in the Eagle Ford shale is taking place in 16 fields

in 24 counties ( Railroad Commission of Texas 2012a ) . Ho wever, this analysis includes 35 counties in the Eagle

Ford shale region. The re ason for including more counties than the RRC lists as existing in the Eagle Ford

shale is that both the Energy Information Administration (EIA) (Figure 1) and the website

EagleFordShale.com 33 have included some counties in the Eagle Ford shale region that are not listed by the

RRC. Additionally, the RRC includes counties in the Eagle Ford shale that have not been listed by these other

sources (Figure 4) ( U.S. Energy Information Administration 2010 ; Dukes, DuBose et al. 2012 ) . Considering

that both the EIA and EagleFordShale.com are websites that seek to predict trends in drilling activity, it is

possible that some counties not listed by the RRC, but which are listed by these other sources, will experience

drilling in the for e seeable future. Therefore, the decision to include counties not listed by the RRC is

intended to ensure that this analysis is relevant to future audiences.

33 EagleFordShale.com is currently hosting a website for the Eagle Ford Task Force, a group formed by current

Railroad Commissioner David Porter to help overcome economic and logistical obstacles of developing the Eagle

Ford shale play. Thi s website provides detailed and referenced information about Eagle Ford shale counties. Since

this website is about development of the shale, it makes sense that the list of counties the website offers might

include counties that the business community exp ects to see drilling at in the near future.46



## Appendix II

– Carbon isotope values

Car bon

- 13 ( 1 3 C ) isotope concentrations are calculated by comparing the ratio of 13 C to 12 C isotopes of carbon

in a given sample of gas, to a predefined standard, Pee Dee Belemnite (PDB). The following equation

( Farquhar, O'Leary et al. 1982 ) describes this comparison:

δ 13 C (‰) = ((R sample /R standard )

– 1) x 1000 Equation 1

In equation 1, R sample represents the ratio of 13 C/ 12 C found in the sample, while R standard represents the ratio of

13 C/ 12 C found in the PDB standard ( Farqu har, O'Leary et al. 1982 ) . The PDB standard has a 13 C isotop e ratio

that is less than one ( Slater, Preston et al. 2001 )

. Therefore, if the concentration of 13 C in a sample is less

than the concentration of 13 C in the standard, the resulting concentration of δ 13 C (‰) would be more

negative than it would have been if the 13 C sample concentration were higher than the standard.

Methane h as a specific δ 13 C concentration (corresponding to when and how it was formed), which is also

referred to as an isotopic signature or “fingerprint.” Naturally occurring methane in a groundwater aquifer

could come from recent microbial degradation of organ ic matter, termed biogenic methane. However,

methane in groundwater could also come from an aquifer’s connection with a deeper source of methane that

was formed from high temperatures and pressures, also called “thermogenic” methane. Thermogenic gas

tend s to have a less negative δ 13 C concentration than biogenic methane ( Schoell 1980 ; Barker and Fritz

1981 ) 34

.

When thermogeni c methane from a shale formation reaches an aquifer that contains more biogenic gas than

thermogenic gas, it would likely mak e the overall concentration of δ 13 C in the aquifer less negative. If only

small amounts of biogenic gas were present before the t hermogenic methane leaked into the aquifer, then

the concentration of methane gas found in the aquifer would very closely resemble the isotopic ratio found

in gas that is produced from the natural gas formation. The extent to which the groundwater δ 13 C

co ncentration s change depends on the quantity and type of thermogenic gas that enters the aquifer.

34 Schoell 1980 Cited in Osborn et al. (2011)47



## Appendix III

– Starting list of potential testing parameters

This list represents the initial list of potential baseline ground water quality analytes. From thi s list, data

availability for each parameter are assessed for each of the counties of interest , and recommendations for

future testing are made based on data availability, health impacts, and cost associated with testing each

parameter.

T ABLE 20 C ATEGORIES OF POTENTI AL BASELINE GROUNDWA TER CHEMISTRY PARAMETERS

.

Category Potential baseline chemical analytical parameters

1. Gas hydrocarbons Methane

Ethane

Propane

Hexane

Total organic carbon

Carbon isotopes

2. Liquid hydrocarbons Total Petroleum Hydrocarbons

Gasoline range organics

Diesel range organics

3. Salts Bicarbonate

Bromide

Calcium

Chloride

Magnesium

Nitrate

Potassium

Selenium

Sodium

Sulfate

Total Dissolved Solids

4. Metals Aluminum

Antimony

Arsenic

Barium

Beryllium

Boron

Cadmium

Ch romium

Cobalt

Copper

Iron

Lead

Manganese

Mercury

Molybdenum48 Nickel

Phosphorus

Potassium

Silver

Strontium

Sulfur

Titanium

Uranium

5. Radioactive elements/parameters Alpha

Beta

Gamma

Uranium

Thorium

Radium 226, 228

Radon 222

Potassium

- 40

6. Volatile organic com pounds (VOCs) Benzene

Toluene

Ethylbenzene

Xylene

7. Polycyclic aromatic hydrocarbons (PAHs) Acenaphthene

Acenaphthylene

Anthracene

Benzo(a) anthracene

Benzo

- (a)

- pyrene

Benzo(b)fluoranthene

Benzo(ghi)perylene

Benzo(k)fluoranthene

Chrys ene

Dibenzo (a,h) anthracene

Fluoranthene

Fluorene

Indeno (1,2,3

- cd) pyrene

Naphthalene

Phenanthrene

Pyrene49



## Appendix III

– Pavillion, WY test results

T ABLE 21 C ONTAMINANTS FOUND IN MONITORING W ELLS DRILLED BY THE EPA IN P AVILLION

, WY

Component found in groundwater Hydraulic fracturing ingredient the

component was used in at the site

 Acetate and benzoic acid

 “Natural breakdown products of

organic contaminants like BTEX and

glycols”

 Benzene, Tol uene, Ethylbenzene,

and Xylene (BTEX)

 Trimethylbenzenes  “Aromatic solvent (usually a BTEX

solution) used in a breaker”

 “Toluene and xylene were used in

flow enhancers and a breaker”

 Chloride

 Potassium chloride used in carbon

dioxide foam hydraulic fractur ing

 Ammonium chloride used in a

crosslinker

 Diesel range organics (DRO)

 “Diesel oil (mixture of saturated

and aromatic hydrocarbons

including naphthalenes and

alkylbenzenes) was used in a guar

polymer slurry/liquid gel

concentrate and in a solvent.”

 “ Petr oleum raffinates (mixture of

paraffinic, cycloparaffinic,

olefinic, and aromatic

hydroc arbons) were used in a

breaker.”

 “ Heavy aromatic petroleum

naphtha (mixture of paraffinic,

cycloparaffinic and aromatic

hydrocarbons) was used in

surfactants and in a so lvent. ”

 guar polymer

 solvent

 Diethylene glycol

 foaming agent

 solvent

 Isopropanol

 biocide

 s urfactant

 b reakers

 foaming agents50  Potassium hydroxide (KOH)

 Potassium metaborate  crosslinker

 solvent

 Triethylene glycol

 solvent

 Tert

- butyl alcohol

 “B reakdown product of methyl

tert

- butyl ether (a fuel additive)

,

and tert

- butyl hydroperoxide (a

gel breaker used in hydraulic

fracturing)”51



## Appendix IV

– RRC groundwater contamination report

In the joint groundwater monitoring and contamination report, the RRC in dicates that BTEX stands for

Benzene, To luene, Ethylbenzene, and Xylene; NG stands for natural gas; but COND is not described. Here it is

assumed that COND stands for Condensate. These codes were consolidated into their respective categories

for analysis as described in Table 4.

T ABLE 22 C ONSOLIDATED CATEGORI ES OF RRC REPORTED CONTAMINANT S

Consolidated category Reported contaminant

BTEX Benzene, dissolved benzene, BTEX

Liquid hydrocarbons hydrocarb, hydrocarb seep, PSH, total pe troleum hydrocarbons (TPH), COND,

condensate, crude oil

Gas hydrocarbons NG, methane

Chlorides Chloride, sodium chloride

F IGURE 12 A CTIVITY STATUS FOR PENDING CASES OF GROUNDWATER CONTAMINATION ATTRIBUTED TO OIL

AND GAS ACTIVIT IES IN 2010 ( T EXAS G ROUNDWATER P ROTECTION C OMMITTEE 2011 )

.

2 3 3 6 9 18 23

0 5 10 15 20 25 Remediation completed. No further action or inspection

required. Violations and contamination due to current activities

found. Contamination confirmed but not fully investigated No violations and historical contamination. Corrective action pending review and approval. Corrective action periodically observed for effectiveness. Corrective action underway.

Number of Cases52

F IGURE 13 M AP OF THE NUMBER OF PENDING GROUNDWATER CONTAMINATION CASES CAUSED BY OIL

AND GAS ACTIVITIES R EPORTED IN 2010 ( T EXAS G ROUNDWATER P ROTECTION C OMMITTEE 2011 )

.53



## Appendix V

– Data preparation

USGS Produced Water Database

The database was filtered for “EAGLEFORD” under the category “RevSAMPFORM.” According to the user

manual, REVSAMPFORM stands for “Revised sample formation name,” and indicates the following:

“Geologic units from which the samples was [sic] produced. Correct ions to SAMPFORM made to be

consistent with stratigraphic columns in the USGS 1995 National Oil and Gas Assessment and the USGS

Geologic Names Lexicon http://ngmdb.usgs.gov/Geolex/geolex_home.htm l ” Additionally, some records in

the database were codes for “null” entries, where no concentration was available. In preparing the dataset

for analysis, values of zero in the USGS produced waters database were interpreted as null entries, as were

valu es of

- 3,

- 2, and

- 1 , because the USGS produced waters database description reads “values of

- 3 replace

original character entries of "ND", "NA" or null entries;

- 2 replace original character entries of "none",

"negative", or "nil",

- 1 replaces original character entries of "trace" and "minor". (Null entries: 0)

. ” ( U.S.

Geological Survey 2002 )



## Kearns (2010)

Geochemical analysis of Eagle Ford core samples taken by Kearns (2010) include major elements, trace

elements, and isotopes listed below. The data were taken at two sites: one in Gonzales County, and one in

De Witt County. The samples in Gonzales County (n=72) represent depths from 8090.5 to 8173.5 feet, while

the samples taken in DeWitt (n=42) Co unty represent depths of 13700.5 to 13828.5 feet ( Kearns 2011 )

.

 N %

 S %

 Ca %

 Ni ppm

 Sr ppm

 TOC %

 Mg %

 Ti %

 Cu ppm

 Zr ppm

 C/N

 Al %

 Mn %

 Zn ppm

 Mo ppm

 δ15N

 Si %

 Fe %

 Th ppm

 δ13C

 P %

 V ppm

 Rb ppm

 TIC %

 K %

 Cr ppm

 U ppm



## TWDB Groundwater Datab ase

The following procedures were used to extract data from the TWDB groundwater quality database:

1. Data for each county was extracted using the “Water Quality Publication Report Query” and each

county code.

2. The data was filtered for reliability codes 08

– 14 and 16 using the column labeled “reliability rem.”

(see Appendix VII

– Reliability codes)

3. Flags indicating quantity boundaries, such as greater than “>” or less than “<,” were ignored when

preceding a concentration.

4. Blanks were revised as “NA” for func tionality with statistical and geospatial analysis software.

5. Zeros were set to “NA” if they deviated substantially from the range of other values in the dataset.

6. Zero values for carbonate were changed to NA values when they made up most of the samples in a

county. For example, no data for carbonate was provided for Wood County.54



## Geospatial Analysis

ESRI was the data source for Texas county boundaries data (ESRI 2000). Location data for water wells in

Texas was acquired from the TWDB’s GIS Data webpage (TWD B GISa; TWDB GISb) . The groundwater quality

data tables were added to the map and then joined by state well number with the TWDB “Well Location

S hapefile ” . Finally, the data were projected in NAD 1983 with no UTM Zone. For displaying graduated colors,

i n some cases the natural breaks (Jenks) method was used to display the range of concentrations. However,

if significant thresholds, such as an MCL, were known for a specific chemical, the displayed concentration

ranges were altered to depict this threshol d.



## Literature Review

L iterature was systematically queried using two databases: ISI Web of Knowledge, and OnePetro. Additional

literature may be included that the author found through other sources. Search terms for the literature

searches were as follo ws:

 “Eagle Ford” AND f ormation

 “Eagle Ford” AND shale

 “ County Name County” Texas55



## Appendix VI

– Stratigraphic column

F IGURE 14 S TRATIGRAPHIC COLUMN OF THE E AGLE F ORD FORMATION (C ONDON AND DYMAN 2006, CITED

IN M ULLEN 2010).56



## Ap pendix V II

– Reliability cod es for groundwater quality

samples in Texas Water Development Board database.

Code Description

01 Not indicative of aquifer quality. Data should be used carefully.

02 Sample collected from well not sufficiently pumped; and n ot filtered or preserved.

Data should still be used carefully.

03 Sample collected from well sufficiently pumped but not filtered or preserved. Holding

time probably not honored.

04 Chemical analysis taken from a report. Sample collection and preserva tion

procedures unknown.

08 Sample filtered in the field. Temperature, conductivity, and pH measured in the field.

Alkalinity measured in the lab. Nutrient sample not preserved and included in anion

sub

- sample. Sample kept cold until delivered to the lab.

09 Same as #08, but not filtered in the field.

10 Sampled in accordance with the TWDB's A Field Manual for Ground

- Water Sampling,

2003. Samples are collected when temperature, conductivity, and pH have stablized.

Sample was filtered and field tested for alkalinity. Samples are preserved as

applicable, kept chilled, and delivered to the lab. Holding times are honored. Organic

sub

- samples are not filtered.

11 Same as #10 but not filtered.

12 Sample collected by TCEQ staff following prescribed QA

- QC pr ocedures.

13 Cation sample preserved and run thru TDH lab. Anion and nutrient sub

- samples sent

to lab at Texas Tech lab and run within 24 hours. Field test completed as described in

#10.

14 Similar to #10 but sample results determined by using a Hach DR

- 2000 lab.

15 Collection procedures not documented, results obtained by use of a Groundwater

Conservation District's Hach equipment.

16 Sample collected by USGS for NAWQA program using "Clean Sample" technique.

99 Reliability unknown, not available, or not yet entered into database. Sample collected

from tank, distribution, or bailed from well.57



## Appendix VIII

– TWDB Groundwater Database Listed

Parameters

Concentrations for the following chemicals and parameters are provided in the Texas Water Devel opment

Board groundwater database:

pH Boron Lead Silicon

Temperature Bromide Lithium Silver

Conductivity Cadmium Magnesium Sodium

Sodium Adsorption Ratio Calcium Manganese Strontium

Total Dissolved Solids Calcium Carbonate Mercury Sufate

Alkalinity Ca rbonate Molybdenum Tellurium

Aluminum Chloride Nitrate Uranium

Antimony Chromium Nitrite plus Nitrate Vanadium

Arsenic Cobalt Oxygen Zinc

Barium Copper Phosphorus

Beryllium Fluoride Potassium

Bicarbonate Iron Selenium58



## Appendix I X

– All In frequent Constituents Identified in the

TWDB Groundwater Database

1,1,1

- TRICHLOROETHANE, TOTAL, UG/L

1,1,2,2

- TETRACHLOROETHANE, TOTAL, UG/L

1,1,2

- TRICHLOROETHANE, TOTAL, UG/L

1,1

- DICHLOROETHANE, TOTAL, UG/L

1,1

- DICHLOROETHYLENE, TOTAL, UG/L

1,2,4

- TRICHLOROBENZENE, TOTAL, UG/L

1,2

- DICHLOROBENZENE, TOTAL, UG/L

1,2

- DICHLOROETHANE, TOTAL, UG/L

1,2

- DICHLOROPROPANE, TOTAL, UG /L

1,2

- DIPHENYLHYDRAZINE, TOTAL, UG/L

1,3

- DICHLOROBENZENE, TOTAL, UG/L

1,4

- DICHLOROBENZENE, TOTAL, UG/L

2, 4, 5

- T, WATER, DISSOLVED, UG/L

2, 4

- D, WATER, DISSOLVED, UG/L

2,4,5

- T, TOTAL, UG/L

2,4,5

- TP INCLUDES ACIDS & SALTS IN WATER, UG/L

2,4,6

- TRICHLOROPHENOL, TOTAL, UG/L

2,4

- D, TOTAL, UG/L

2,4

- DICHLOROPHENOL, TO TAL, UG/L

2,4

- DIMETHYLPHENOL, TOTAL, UG/L

2,4

- DINITROPHENOL, TOTAL, UG/L

2,4

- DINITROTOLUENE, TOTAL, UG/L

2,6

- DINITRO

- 2

- CRESOL, TOTAL, UG/L

2,6

- DINITROTOLUENE , TOTAL, UG/L

2

- CHLOROETHYL VINYL ETHER, TOTAL, UG/L

2

- CHLORONAPHTHALENE, TOTAL, UG/L

2

- NITROPHENOL, TOTAL, UG/L

3,3'

- DICHLOROBENZIDINE, TOTAL, UG/L

4,4'

- DDD, TOTA L, UG/L

4,4'

- DDE, TOTAL, UG/L

4,4'

- DDT, TOTAL, UG/L

4

- BROMOPHENYL PHENYL ETHER, TOTAL, UG/L

4

- CHLORO

- 3

- CRESOL, TOTAL, UG/L

4

- CHLOROPH ENYL PHENYL ETHER, TOTAL, UG/L

4

- NITROPHENOL, TOTAL, UG/L

A

- BHC

- ALPHA, TOTAL, UG/L

ACENAPHTHENE, TOTAL, UG/L

ACENAPHTHYLENE, TOTAL, UG/L

ACROLE IN, DISSOLVED, UG/L

ACRYLONITRILE, DISSOLVED, UG/L ALACHLOR, TOTAL, UG/L

ALDRIN, TOTAL, UG/L

ALKALINITY PHENOLPHTHALEIN FIELD DATA (MG/L)

AL KALINITY, FIELD, DISSOLVED AS CACO3

ALKALINITY, TOTAL (MG/L AS CACO3)

ALPHA, DISSOLVED (PC/L)

ALPHA, TOTAL (PC/L)

ALUMINUM, DISSOLVED (UG/L AS AL)

ALUMINUM, TOTAL (UG/L AS AL)

ANION/CATION CHG BAL, PERCENT

ANTHRACENE, TOTAL, UG/L

ANTIMONY, DISSOLVED (UG/L AS SB)

ANTIMONY, TOTAL (UG/L AS SB)

ARSENIC, DISSOLVED (UG/L AS AS)

ARSENIC, TOTAL (UG/L AS AS)

BANVEL (DICAMBA), TOTAL, UG/L

BARIUM, DISSOLVED (UG/L AS BA)

BARIUM, TOTAL (UG/L AS BA)

B

- BHC

- BETA, TOTAL, UG/L

BENZENE, VOLATILE ANALYSIS, TOTAL, UG/L

BENZIDINE, TOTAL, UG/L

BENZO(A) ANTHRACENE, TOTAL, UG/L

BENZO

- (A)

- PYRENE, TOTAL, UG/L

BENZO(B)FLUORANTHENE, TOTAL, UG/L

BENZO(GHI)PERYLENE, TOTAL, UG/L

BENZO(K)FLUORANTHENE, TOTAL, UG/L

BERYLLIUM, DISSOLVED (UG/L AS BE)

BERYLLIUM, TOTAL (UG/L AS BE)

BETA, DISSOLVED (PC/L)

BETA, TOTAL (PC/L)

BIS (2

- CHLOROETHOXY) METHANE, TOTAL, UG/L

BIS (2

- CHLOROETHYL) ETHER, TOTAL, UG/L

BIS (2

- CHLOROISOPROPYL) ETHER, TOTAL, UG/L

BIS(2

- ETHYLHEXYL) PHTHALATE, TOTAL, UG/L

BISPHENOL, TOTAL, UG/L

BORON, DISSOLVED (UG/L AS B)

BROMIDE, DISSOLVED, (MG/L AS BR)

BROMIDE, DISSOLVED, (UG/L AS BR)

BROMODICHLOROMETHANE, TOTAL, UG/L

BROMOFORM, TOTAL, UG/L59

BROMOMETHANE, TOTAL, UG/L

BUTYLBENZYL PHTHALATE, TOTAL, UG/L

CADMIUM, DISSOLVED (UG /L AS CD)

CADMIUM, TOTAL (UG/L)

CALCIUM, DISSOLVED (MG/L AS CA)

CARBON DIOXIDE (MG/L AS CO2)

CARBON TETRACHLORIDE, TOTAL, UG/L

CARBON, TOTAL (MG/ L AS C)

CARBON, TOTAL INORGANIC (MG/L AS C)

CARBON, TOTAL ORGANIC (MG/L AS C)

CARBON

- 13 / CARBON

- 12 STABLE ISOTOPE RATIO PER

MIL

CARBON

- 14 DISS APPARENT AGE (YEARS BP)

CARBON

- 14 FRAC TION MODERN

CHLORDANE, TOTAL, UG/L

CHLORIDE, TOTAL (MG/L AS CL)

CHLOROBENZENE, TOTAL, UG/L

CHLORODIBROMOMETHANE, TOTAL, UG/L

CHLOROETHA NE, TOTAL, UG/L

CHLOROFORM, TOTAL, UG/L

CHLOROMETHANE, TOTAL, UG/L

CHLOROPHENOL, TOTAL, UG/L

CHROMIUM, DISSOLVED (UG/L AS CR)

CHROMI UM, FIELD ACIDIFIED W/HNO3, FILTERED,

UG/L

CHROMIUM, TOTAL (UG/L AS CR)

CHRYSENE, TOTAL, UG/L

CIS

- 1,3

- DICHLOROPROPENE, TOTAL, UG/L

CIS

- 1,3

- DICHLOROPROPYLENE, TOTAL, UG/L

CO BALT, DISSOLVED (UG/L AS CO)

COPPER, DISSOLVED (UG/L AS CU)

COPPER, TOTAL (UG/L AS CU)

CYCLOHEXANONE, TOTAL, UG/L

DACTHAL (DCPA), TOTAL, UG/L

DDD, TOTAL, UG/L

DDE, TOTAL, UG/L

DDT, TOTAL, UG/L

DELTA

- BHC, TOTAL, UG/L

DEUTERIUM, EXPRESSED AS PERMIL VSMOW

DIAZINON, TOTAL, UG/L

DIBENZO (A,H) ANTHRACENE, TOTAL, UG/L

DIBROMOCHLOROMETHANE, TOTAL, UG/L

DIELDRIN, TOTAL, UG/L DIETHYL PTHALATE, TOTAL, UG/L

DIMETHYL PTHALATE, TOTAL, UG/L

DI

- N

- BUTYL PHTHALATE, TOTAL, UG/L

DI

- N

- OCTYL PHTHALATE, TOTAL, UG/L

DIPHENYLAMINE, TOTAL, UG/L

DURSBAN (CHLOROPYRIFOS), TOTAL, UG/L

ENDOSULFAN

- ALPHA, TOTAL, UG/L

ENDOSULFAN

- BETA, TOTAL, UG/L

ENDOSULFAN SULFATE, TOTAL, UG/L

ENDOSULFAN, TOTAL, UG/L

ENDRIN ALDEHYDE, TOTAL, UG/L

ENDRIN, TOTAL, UG/L

ETHYL PARATHION, TOTAL, UG/L

ETHYLBENZENE IN WATER, UG/L

FLUORANTHENE, TOTAL, UG/L

FLUORENE, TOTAL, UG/L

FLUORIDE, TOTAL (MG/L AS F)

GAMMA

- BHC (LINDANE), TOTAL, UG/L

GROSS ALPHA RADIATION,TOTAL, PRODUCED

WATER(pCi/L)

GROSS BETA RADIATION, TOTAL, PRODUCED

WATER(pCi/L)

HALOGEN, TOTAL ORGANIC, UG /L

HARDNESS, NON

- CARBONATE (MG/L AS CACO3)

HARDNESS, TOTAL (MG/L AS CACO3)

HEPTACHLOR EPOXIDE, TOTAL, UG/L

HEPTACHLOR, TOTAL, UG/L

HEXACHLOROBENZENE (HCB ), TOTAL, UG/L

HEXACHLOROBUTADIENE, TOTAL, UG/L

HEXACHLOROCYCLOPENTADIENE, TOTAL, UG/L

HEXACHLOROETHANE, TOTAL, UG/L

HYDROGEN ION CONCENTRATION, TOTAL (MG/L)

HYDROGEN SULFIDE, MG/L

HYDROXIDE ION (MG/L AS OH)

INDENO (1,2,3

- CD) PYRENE

IODIDE (MG/L AS I)

IRON, DISSOLVED (UG/L AS FE)

IRON, TOTAL (U G/L AS FE)

ISOPHORONE, TOTAL, UG/L

LEAD, DISSOLVED (UG/L AS PB)

LEAD, FIELD FILTERED, ACIDIFIED W/HNO3, UG/L

LEAD, TOTAL (UG/L AS PB)

LINDANE, T OTAL, UG/L60

LITHIUM, DISSOLVED (UG/L AS LI)

LITHIUM, TOTAL (UG/L AS LI)

MAGNESIUM, DISSOLVED (MG/L AS MG)

MAGNESIUM, TOTAL (MG/L AS MG)

MALATH ION, TOTAL, UG/L

MANGANESE, DISSOLVED (UG/L AS MN)

MANGANESE, TOTAL (UG/L AS MN)

MERCURY, DISSOLVED (UG/L AS HG)

MERCURY, TOTAL (UG/L AS HG)

ME THOXYCHLOR, TOTAL, UG/L

METHYL PARATHION, TOTAL, UG/L

METHYLENE CHLORIDE, TOTAL, UG/L

MOLYBDENUM, DISSOLVED, UG/L

NAPHTHALENE, TOTAL, UG/L

NICKEL, DISSOLVED (UG/L AS NI)

NICKEL, TOTAL (UG/L AS NI)

NITRATE NITROGEN, DISSOLVED (MG/L AS N)

NITRATE NITROGEN, TOTAL (MG/L AS N)

NITRITE NITROGEN, DISSOLVED (MG/L AS N)

NITRITE NITROGEN, TOTAL (MG/L AS N)

NITRITE NITROGEN, TOTAL (MG/L AS NO2)

NITRITE PLUS NITRATE, DISSOLVED (MG/L AS N)

NITRITE PLUS NITRATE, TOTAL (MG/L AS N)

NITROBENZENE, TOTAL, UG/L

NITROGEN, AMMONIA, DISSOLVED (MG/L AS N)

NITROGEN, AMMONIA, TOTAL (MG/L AS N)

NITROGEN, KJELDAHL, DISSOLVED (MG/L AS N)

NITROGEN, ORGANIC, TOTAL (MG/L AS N)

N

- NITROSODIMETHLAMINE, TOTAL, UG/L

N

- NITROSO

- DI

- N

- PROPYLAMINE, TOTAL, UG/L

N

- NITROSODIPHENYLAMINE, TOTAL, UG/L

OXIDATION REDUCTION POTENTIAL (ORP), MILLIVOLTS

OXYGEN, DISSOLVED (MG/L)

OXYGEN, DISSOLVED, ANALYSIS BY PRO BE (MG/L)

OXYGEN

- 18, EXPRESSED AS PERMIL VSMOW

OXYGEN

- 18/OXYGEN

- 16 OF SULFATE (RATIO PER MIL)

PCB

- 1221, TOTAL, UG/L

PCB

- 1232, TOTAL, UG/L

PCB

- 1242, TOTAL, UG/L

PCB

- 1248, TOTAL, UG/L

PCB

- 1254, TOTAL, UG/L

PCB

- 1260, TOTAL, UG/L

PCB

- 1262 (ARACLOR), TOTAL, UG/L PCB

- 1016, TOTAL, UG/L

PENTACHLOROPHENOL (PCP), TOTAL, UG/L

PH (STANDARD UNITS) LAB

PH (STANDARD UNITS), FIELD

PHENANTHRENE, TOTAL, UG/L

PHENOL, TOTAL, UG/L

PHOSPHORUS, DISSOLVED (MG/L AS P)

PHOSPHORUS, DISSOLVED ORTHOPHOSPHATE (MG/L

AS P)

PHOSPHORUS, IN TOTAL ORTHOPHOSPHATE (MG/L AS

P)

PHOSPHORUS, TOTAL (MG/L AS P)

PHOSPHORUS, TOTAL AS PO4 (MG/L)

PICLORAM, TOTAL, UG/L

POTASSIUM 40 (K

- 40), DISSOLVED, PC/L

POTASSIUM, DISSOLVED (MG/L AS K)

PURGEABLE ORGANIC CARBON, UG/L

PYRENE, TOTAL, UG/L

RADIUM 226 + RADIUM 228, DISSOLVED, PC/L

RADIUM 226 + RADIUM 228, TOTAL, PC/L

RADIUM 226, DISSOLVED, PC/L

RADIUM 226, DISSOLVED, RADON METHOD, PC/L

RADIUM 226 , TOTAL, PC/L

RADIUM 228, DISSOLVED (PC/L AS RA

- 228)

RADIUM 228, TOTAL, PC/L

RADON 222, DISSOLVED, PC/L

RESIDUE, TOTAL FILTERABLE (DRIED AT 180C), MG/L

SELENI UM, DISSOLVED (UG/L AS SE)

SELENIUM, TOTAL (UG/L)

SILVER, DISSOLVED (UG/L AS AG)

SILVER, FIELD FILTERED, ACIDIFIED W/HNO3, UG/L

SILVER, TOTAL (UG/L AS AG)

SI LVEX, TOTAL, UG/L

SODIUM CHLORIDE (NACL), MG/L

SODIUM PLUS POTASSIUM (MG/L)

SODIUM, DISSOLVED (MG/L AS NA)

SOLIDS, SUSPENDED, RESIDUE ON EVAP AT 180C,

MG/L

SPECIFIC CONDUCTANCE, FIELD (UMHOS/CM AT 25C)

STRONTIUM, DISSOLVED (UG/L AS SR)

STRONTIUM, ISOTOPE OF MASS 86 AND 87 RATIO

SULFATE, TOTAL (MG/L AS SO4)

SULFIDE, DISSOLVED (MG/L AS S)

SULFUR

- 34/32 OF SULFATE, DISSOLVED, PER MIL61

TEMPERATURE, WATER (CELSIUS)

TETRACHLOROETHYLENE, DISSOLVED, UG/L

THALLIUM, DISSOLVED (UG/L AS TL)

THALLIUM, TOTAL (UG/L AS TL)

THORIUM, NATURAL, DISSOLVED PC/L

TIN, TOTAL (UG/L AS SN)

TOLUENE, VOLATILE ANALYSIS, TOTAL, UG/L

TOTAL PETROLEUM HYDROCARNON mg/L

TOXAPHENE, TOTAL, UG/L

TRANS

- 1,2

- DICHLOROETHYLENE, TOTAL, UG/L

TRANS

- 1,3

- DICHLOROPROPENE, TOTAL, UG/L

TRANS

- 1,3

- DICHLOROPROPYLENE, TOTAL, UG/L

TRICHLOROETHYLENE, TOTAL, UG/L

TRICHLOROFLUOROMETHANE, TOTAL, UG/ L TRITIUM COUNTING ERROR

TRITIUM IN WATER (TRITIUM UNITS)

TRITIUM, DISSOLVED (TRITIUM UNITS)

TRITIUM, TOTAL (TRITIUM UNITS)

TURBIDITY, LAB, NEPHELOMETRIC TURBIDITY UNITS,

NTU

URANIUM, NATURAL, DISSOLVED, UG/L

URANIUM, NATURAL, TOTAL (PC/L AS U)

VANADIUM, DISSOLVED (UG/L AS V)

VINYL CHLORIDE, TOTAL, UG/L

XYLENE, TOTAL, UG/L

ZINC, DISSOLVED (UG/L AS ZN)

ZINC, TOTAL (UG/L AS ZN)62



## Appendix X

- Carbon isotope ratios by depth

F IGURE 15 13 C/ 12 C STABLE ISOTOPE RATIO S IN GROUNDWATE R BY DEPTH IN THE COUNTIES OF I NTEREST

.

F IGURE 16 C OUNTIES WHERE 13 C/ 12 C STABLE ISOTOPE RATIO DATA FOR GROUNDWATER OR CORE SAMPLES

ARE AVAILABLE

. 0

500

1000

1500

2000

2500

3000

3500 -20 -15 -10 -5 0

Depth (ft) 13 

## C/ 12 

## C stable isotope ratio ( ‰)63 T ABLE 23 C ARBON ISOTOPE RANGES FOR GROUNDWATER IN THE CO UNTIES OF INTEREST

.

County Number of samples 13 C/ 12 C

Brazos 1

- 10.1

Burleson 1

- 14.5

Colorado 2

- 11.3 to

- 7.9

Dimmit 2

- 18.1 to

- 12.1

Duval 4

- 13.2 to

- 8.2

Karnes 2

- 10.6 to

- 7.2

La Salle 1

- 9.6

Lavaca 6

- 13.1 to

- 7.3

Live Oak 4

- 10.9 to

- 8.3

Webb 1

- 10.7

Zavala 2

- 11.8 to

- 9.9

Total 26

F IGURE 17 D ISTRIBUTION OF CARBON ISOTOPE RA NGES FOUND IN GROUND WATER IN E AGLE F ORD SHALE

COUNTIES

.64

F IGURE 18 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR GAS

HYDROCARBONS WITH IN E AGLE F ORD SHALE COUNTIES

. T ESTING CODES : A = AS NEEDED

, R =

RECOMMENDED

, T = TESTING NEEDED

County Total w ells Total organic c arbon 13 C/ 12 C

Bastrop 791 13 1.6% T T

Bee 631 1 0.2% T T

Brazos 687 T 1 0.1% T

Burleson 847 T 1 0.1% T

Colorado 574 11 1.9% T 2 0.3% T

Dimmit 527 T 2 0.4% T

Duval 683 1 0.1% T 4 0.6% T

Edwards 604 0.0% T 3 0.5% T

Fayette 863 12 1.4% T T

Goliad 507 1 0.2% T 5 1.0% T

Karnes 410 T 2 0.5% T

La Salle 362 T 1 0.3% T

Lavaca 386 T 6 1.6% T

Live Oak 540 5 0.9% T 5 0.9% T

Webb 339 9 2.7% T 1 0.3% T

Zavala 748 T 2 0.3% T65



## Appendix XI

– Salts

Produced water comparison with groundwater

T ABLE 24 W OOD C OUNTY T

- TEST RESULTS FOR PRO DUCED WATER COMPARED TO GROUNDWATER ; A LL

CONCENTRATIONS MEASU RED IN MG / L

, EXCEPT FOR P H. 35

Parameter Mean of the

differences p

- value t df Lower 95% CI Upper 95% CI

pH

- 0.3834286 0.1175

- 1.6063 34

- 0.8685358 0.1016787

Bicarbonate 225.9209 3.86E

- 12 10.7383 32 183.0664 268.7754

Calcium 1978.569 0 24.5712 33 1814.742 2142.396

Chloride 52614.51 0 46.3473 34 50307.46 54921.56

Magnesium 444.2947 0 24.845 33 407.9122 480.6772

Sodium 31611.01 0 52.758 32 30390.54 32831.47

Sulfate

- 7.293103 0.1655

- 1.4241 28

- 17.783536 3.197329

Tot al Dissolved

Solids 86411.64 0 43.3803 32 82354.16 90469.12

T ABLE 25 W OOD C OUNTY SUMMARY STATIS TICS

. WW = PRODUCED WATER

, GW = GROUNDWATER ; A LL

CONCENTRATIONS MEASU RED IN MG / L

, EXCEPT FOR P H. 36

Parameter n Mean Min. 1st Qu. Median 3rd Qu. Max

WW pH 35 7.096 6.4 7.025 7.15 7.25 7.45

GW pH 55 7.472 4.22 6.525 7.91 8.47 8.89

WW

Bicarbonate 35 414.7 137 366.5 430 459 570

GW Bicarbonate 53 176.63 24.41 125.69 170.85 218.44 452.75

WW Calcium 35 1990 1156 1631 1894 2432 2761

GW Calci um 54 10.14 0.76 1.975 3.425 8.23 61

WW Chloride 35 52651 26562 52497 54285 55156 60965

GW Chloride 55 34.142 1 8.055 14.3 38.4 285

WW

Magnesium 35 445.5 205 399 415 518 638

GW Magnesium 53 2.066 0.2 0.5 1 1.4 11.8

WW Sodium 34 31665 13590 31356 32110 32802 35963

GW Sodium 53 82.19 2.09 36.8 81 106 344

WW Sulfate 29 17.28 3 12 17 22 48

GW Sulfate 54 23.36 1 10.22 18.3 34.85 95

WW TDS 35 86702 43435 86487 89366 90671 100321

GW TDS 52 266.3 56 204.8 251.5 308.5 887

35 For p

- values of zero, the p

- value returned in the statistical software used, “R,” is “<2.2e

- 16” which is coded as

“***” and indicates a p

- value of 0.66

T ABLE 26 A LL E AGLE F ORD SHALE C OUNTIES : T

- TEST RESULTS FOR PRO DUCED WATER COMPARED TO

GROUNDWATER

. TDS = T OTAL D ISSOLVED S OLIDS ; A LL CONCENTRATIONS ME ASURED IN MG / L

, EXCEPT

FOR P H.

Parameter Mean of the

differences p

- value t df Lower 95% CI Upper 95%

CI

pH

- 0.220 177 0 2827 1524

- 0.2693818

- 0.1709723

Bicarbonate 536.3342 0 26.6662 1583 496.8834 575.7849

Calcium 2355.311 0 16.8098 1593 2080.48 2630.142

Chloride 26434.53 0 28.7776 1591 24632.77 28236.28

Magnesium 305.6848 0 16.9282 1570 270.2651 341.1045

Sodium 14162.53 0 32.3223 1562 13303.07 15021.98

Sulfate 202.6485 1.62E

- 09 6.0823 1121 137.2767 268.0203

TDS 44018.91 0 29.5107 1569 41093.12 46944.7

Potassium 147.9325 7.27E

- 08 5.6843 141 96.48327 199.3818

T ABLE 27 A LL C OUNTIES IN TH E E AGLE F ORD SHALE REGION : SUMMARY STATISTICS

. WW = PRODUCED

WATER

, GW = GROUNDWATER

. A LL CONCENTRATIONS ME ASURED IN MG / L

, EXCEPT FOR P H.

Parameter n Mean Min 1st Qu. Median 3rd Qu. Max

WW pH 1555 7.254 5 6.65 7.4 7.9 8.9

GW pH 2827 7.459 4.14 7 7.37 7. 96 9.86

WW Bicarbonate 2881 898.2 3 344.5 701 1185.5 4731

GW Bicarbonate 2864 333.4 0 214.8 290.4 366.1 2374.8

WW Calcium 1600 2412.3 1 37 189.5 1521.2 40992

GW Calcium 2877 55.96 0.1 6.84 40.7 83 909

WW Chloride 1605 26751 490 3589 11876 32517 245367

GW Chloride 2869 187.6 1 30.7 75.3 194 9579

WW Magnesium 1577 317.8 1 17 51 338 17205

GW Magnesium 2876 12.501 0 1.518 6.55 15.1 327

WW Sodium 1589 14398 148 2725 7357 18061 123775

GW Sodium 2835 213.3 1.1 51.6 119 248 7230

WW Sulfate 1128 336.3 1 1 3 43 210 14100

GW Sulfate 2868 117.4 0 18.68 46.5 109 2830

WW TDS 1603 45032 1033 7568 21275 54148 398024

GW TDS 1543 795.6 36 333 538 909 17606

WW Potassium 143 155.6 2 10 15 138.5 1635

GW Potassium 2832 6.37 0 2.498 4.64 7.482 13467



## Salts data a v ailability

T ABLE 28 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

FOUND IN PRODUCED WA TER IN A TASCOSA

, A USTIN

, B ASTROP

, B EE

, AND B RAZOS C OUNTIES

. T ESTING

CODES : A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

County Atascosa Austin Bastrop Bee Brazos

Total wells 1117 321 791 631 687

TDS 180 16% A 67 21% A 84 11% A 43 7% A 72 10% A

Chloride 182 16% A 68 21% A 84 11% A 43 7% A 72 10% A

Sodium 180 16% A 68 21% A 84 11% A 44 7% A 73 11% A

Sulfate 182 16% A 68 21% A 84 11% A 43 7% A 72 10% A

Calcium 182 16% A 68 21% A 84 11% A 44 7% A 73 11% A

Magnesium 182 16% A 68 21% A 84 11% A 44 7% A 73 11% A

Bicarbonate 182 16% A 67 21% A 84 1 1% A 44 7% A 73 11% A

Potassium 176 16% A 68 21% A 84 11% A 42 7% A 73 11% A

T ABLE 29 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

FOUND IN PRODUCED WA TER IN B URLESON

, C ALDWELL

, C OLORADO

, D EWITT

, AND D IMMIT C OUNTIES

. T ESTING CODES : A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County Burleson Caldwell Colorado De Witt Dimmit

Total wells 847 599 574 513 527

TDS 85 10% A 25 4% T 104 18% A 40 8% A 97 18% A

Chloride 85 10% A 25 4% T 105 18% A 40 8% A 99 19% A

Sodium 85 10% A 25 4% T 104 18% A 40 8% A 98 19% A

Sulfate 85 10% A 25 4% T 105 18% A 40 8% A 99 19% A

Calcium 85 10% A 25 4% T 105 18% A 40 8% A 100 19% A

Magnesium 85 10% A 25 4 % T 105 18% A 40 8% A 100 19% A

Bicarbonate 85 10% A 25 4% T 105 18% A 40 8% A 99 19% A

Potassium 85 10% A 24 4% T 104 18% A 40 8% A 98 19% A68

T ABLE 30 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SA LTS

FOUND IN PRODUCED WA TER IN D UVAL

, E DWARDS

, F AYETTE

, F RIO

, AND G OLIAD C OUNTIES

. T ESTING

CODES : A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County Duval Edwards Fayette Frio Goliad

Total well s 683 604 863 756 507

TDS 129 19% A 75 12% A 60 7% A 140 19% A 42 8% A

Chloride 129 19% A 79 105% A 60 7% A 143 19% A 42 8% A

Sodium 129 19% A 75 95% A 60 7% A 140 19% A 42 8% A

Sulfate 129 19% A 79 105% A 60 7% A 143 19% A 42 8% A

Calcium 129 19% A 79 100% A 60 7% A 143 19% A 42 8% A

Magnesium 129 19% A 79 100% A 60 7% A 143 19% A 42 8% A

Bicarbonate 129 19% A 76 96% A 60 7% A 142 19% A 42 8% A

Potassium 129 19% A 79 104% A 60 7% A 140 19% A 42 8% A

T ABLE 31 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

FOUND IN PRODUCED WA TER IN G ONZALES

, G RIMES

, G UADALUPE

, H OUSTON

, K ARNES C OUNTIES

. T ESTING

CODES : A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County Gonzales Grimes Guadalupe Houston Karnes

Total wells 582 357 638 400 410

TDS 277 48% A 40 11% A 18 3% T 81 20% A 43 10% A

Chloride 277 48% A 41 11% A 18 3% T 82 21% A 43 10% A

Sodium 277 48% A 40 11% A 18 3% T 81 20% A 43 10% A

Sulfate 277 48% A 41 11% A 18 3% T 82 21% A 43 10% A

Calcium 277 48% A 41 11% A 18 3% T 82 21% A 43 10% A

Magnesium 277 48% A 41 11% A 18 3% T 82 21% A 43 10% A

Bicarbonate 277 48% A 41 11% A 18 3% T 82 21% A 43 10% A

Potassium 277 48% A 41 11% A 17 3% T 82 21% A 41 10% A

T ABLE 32 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

FOUND IN PRODUCED WA TER IN L A S ALLE

, L AVACA

, L EE

, L EON

, AND L IVE O AK C OUNTIES

. T ESTING CODES :

A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County La Salle Lavaca Lee Leon Live Oak

Total well s 362 386 399 323 540

TDS 84 23% A 96 25% A 65 16% A 73 23% A 65 12% A

Chloride 85 23% A 97 25% A 73 18% A 73 23% A 65 12% A

Sodium 84 23% A 96 25% A 66 17% A 75 23% A 65 12% A

Sulfate 85 23% A 97 25% A 73 18% A 73 23% A 65 12% A

Calcium 85 23% A 97 25% A 74 19% A 75 23% A 65 12% A

Magnesium 85 23% A 97 25% A 74 19% A 75 23% A 65 12% A69

Bicarbonate 85 23% A 97 25% A 71 18% A 75 23% A 65 12% A

Potassium 83 23% A 97 25% A 66 17% A 74 23% A 65 12% A

T ABLE 33 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

FOUND IN PRODUCED WA TER IN M ADISON

, M AVERICK

, M C M ULLEN

, M ILAM

, AND R OBERTSON C OUNTIES

. T ESTING CODES : A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County Madison Maverick McMullen Milam Robertson

Total wells 365 92 184 314 824

TDS 36 10% R 64 70% A 47 26% A 70 22% A 95 12% A

Chloride 37 10% R 66 72% A 47 26% A 78 25% A 96 12% A

Sodium 37 10% R 64 70% A 47 26% A 71 23% A 96 12% A

Sulfate 37 10% R 65 71% A 48 26% A 78 25% A 96 12% A

Calcium 37 10% R 66 72% A 48 26% A 79 25% A 97 12% A

Mag nesium 37 10% R 66 72% A 48 26% A 79 25% A 97 12% A

Bicarbonate 37 10% R 66 72% A 48 26% A 78 25% A 97 12% A

Potassium 37 10% R 65 71% A 48 26% A 71 23% A 96 12% A

T ABLE 34 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TESTING NEEDS FOR SA LTS

FOUND IN PRODUCED WA TER IN W ASHINGTON

, W EBB

, W ILSON

, W OOD

, AND Z AVALA C OUNTIES

. T ESTING

CODES : A = AS NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

County Washington Webb Wilson Wood Zavala

Total wells 478 339 512 442 748

TDS 37 8% R 126 37% A 95 19% A 52 12% A 114 15% A

Chloride 38 8% A 127 37% A 100 20% A 55 12% A 115 15% A

Sodium 37 8% R 127 37% A 97 19% A 53 12% A 114 15% A

Sulfate 38 8% A 127 37% A 100 20% A 54 1 2% A 115 15% A

Calcium 38 8% A 127 37% A 100 20% A 54 12% A 115 15% A

Magnesium 38 8% A 127 37% A 100 20% A 53 12% A 115 15% A

Bicarbonate 38 8% A 126 37% A 98 19% A 54 12% A 115 15% A

Potassium 38 8% A 127 37% A 96 19% A 53 12% A 114 15% A70

F IGURE 19 T OTAL DISSOLVED SOLID S (TDS) CONCENTRATIONS IN TH E E AGLE F ORD SHALE REGION

.71



## Regulated s alts d ata a vailability

T ABLE 35 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR SALTS

W ITH PRIMARY DRINKING WATER STANDARDS IN E AGLE F ORD SHALE COUNTIES

. T ESTING CODES : A = AS

NEEDED

, R = RECOMMENDED

, T = TESTING NEEDED

Total wells Bromide Nitrate Selenium

Atascosa 1117 168 15% A 41 4% A 174 16% A

Austin 321 67 21% A 13 4% T 67 21% A

Bastrop 791 62 8% A 15 2% T 78 10% A

Bee 631 40 6% A 13 2% T 42 7% A

Brazos 687 62 9% A 15 2% T 72 10% A

Burleson 847 70 8% A 22 3% T 76 9% A

Caldwell 599 13 2% T 4 1% T 17 3% T

Colorado 574 87 15% A 22 4% T 95 17% A

De Witt 513 38 7% A 10 2% T 39 8% A

Dimmit 527 103 20% A 35 7% R 104 20% A

Duval 683 139 20% A 17 2% T 141 21% A

Edwards 604 66 11% A 15 2% T 66 11% A

Fayette 863 45 5% A 18 2% T 56 6% A

Frio 756 130 17% A 39 5% A 137 18% A

Goliad 507 41 8% A 15 3% T 42 8% A

Gonzales 582 197 34% A 14 2% T 207 36% A

Grimes 357 39 11% A 17 5% T 40 11% A

Guadalupe 638 14 2% T 3 0% T 17 3% T

Houston 400 66 17% A 17 4% T 79 20% A

Karnes 410 37 9% R 11 3% T 40 10% A

La Salle 362 72 20% A 19 5% T 88 24% A

Lavaca 386 95 25% A 19 5% T 95 25% A

Lee 399 50 13% A 15 4% T 55 14% A

Leon 323 56 17% A 20 6% T 72 22% A

Live Oak 540 72 13% A 26 5% R 75 14% A

Madison 365 28 8% R 9 2% T 34 9% R

Maverick 92 8 9% T 56 61% A 36 39% R

McMullen 184 35 19% R 13 7% T 43 23% A

Milam 314 52 17% A 17 5 % T 53 17% A

Robertson 824 75 9% A 14 2% T 83 10% A

Washington 478 42 9% A 19 4% T 42 9% A

Webb 339 114 34% A 37 11% R 119 35% A

Wilson 512 92 18% A 23 4% T 93 18% A

Wood 442 33 7% R 20 5% T 52 12% A

Zavala 748 104 14% A 22 3% T 114 15% A72



## Appendix XII

– Metals : number of samples

T ABLE 36 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TESTING NEEDS FOR ME TALS

IN A TASCOSA

, A USTIN

, B ASTROP

, B EE

, AND B RAZOS C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T =

T ESTING NEEDED

Atascosa Austin Bastrop Bee Brazos

Total wells 1117 321 791 631 687

Aluminum 167 15% A 54 17% A 60 8% A 30 5% R 66 10% A

Antimony 139 12% A 53 17% A 56 7% A 28 4% R 60 9% A

Arsenic 179 16% A 67 21% A 78 10% A 42 7% A 74 11% A

Barium 179 16% A 67 21% A 80 10% A 42 7% A 75 11% A

Beryllium 139 12% A 54 17% A 56 7% A 29 5% R 60 9% A

Boron 229 21% A 75 23% A 106 13% A 34 5% R 118 17% A

Cadmi um 174 16% A 54 17% A 76 10% A 30 5% R 69 10% A

Chromium 174 16% A 54 17% A 67 8% A 30 5% R 69 10% A

Cobalt 140 13% A 54 17% A 56 7% A 29 5% R 60 9% A

Copper 179 16% A 67 21% A 78 10% A 43 7% A 74 11% A

Iron 204 18% A 71 22% A 146 18% A 44 7% A 75 11% A

Lead 179 16% A 67 21% A 69 9% A 42 7% A 74 11% A

Manganese 180 16% A 67 21% A 81 10% A 44 7% A 74 11% A

Mercury 60 5% A 26 8% R 33 4% R 17 3% T 21 3% T

Molybdenum 167 15% A 54 17% A 58 7% A 35 6% R 66 10% A

Nickel 86 8% A 27 8% R 28 4% R 2 1 3% T 41 6% A

Phosphorus 60 5% A 13 4% T 29 4% R 1 0% T 14 2% T

Silver 60 5% A 26 8% R 24 3% T 17 3% T 20 3% T

Strontium 139 12% A 54 17% A 56 7% A 29 5% R 60 9% A

T ABLE 37 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

Burleson Caldwell Colorado De Witt Dimmit

Total wells 847 599 574 513 527

Aluminum 76 9% A 13 2% T 78 14% A 28 5% R 104 20% A

Antimony 69 91% A 13 2% T 78 14% A 28 5% R 67 13% A

Arsenic 81 117% A 17 3% T 94 16% A 39 5% A 104 20% A

Barium 81 100% A 17 3% T 98 17% A 39 5% A 104 20% A

Beryllium 69 85% A 13 2% T 78 14% A 28 5% R 69 13% A

Boron 137 199% A 36 6% R 135 24% A 49 5% A 125 24% A

Cadmium 73 53% A 17 3% T 74 13% A 29 5% R 97 18% A

Chromium 73 100% A 17 3% T 68 12% A 29 5% R 97 18% A

Cobalt 69 95% A 13 2% T 78 14% A 28 5% R 69 13% A

Copper 81 117% A 17 3% T 94 16% A 39 5% A 104 20% A73

Iron 87 107% A 45 8% A 104 18% A 61 5% A 105 20% A

Lead 81 93% A 17 3% T 88 15% A 39 5% A 104 20% A

Manganese 81 100% A 17 3% T 91 16% A 39 5% A 104 20% A

Mercury 20 25% T 7 1% T 35 6% R 16 5% T 51 10% A

Molybdenum 76 380% A 13 2% T 78 14% A 28 5% R 104 20% A

Nickel 55 72% A 8 1% T 39 7% A 18 5% T 40 8% A

Phosphorus 23 42% T 14 2% T 6 1% T 5% T 26 5% R

Silver 20 26% T 7 1% T 29 5% R 16 5% T 51 10% A

Strontium 64 320% A 13 2% T 78 14% A 28 5% R 69 13% A

T ABLE 38 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

Duval Edwards Fayette Frio Goliad

Total wells 683 604 863 756 507

Aluminum 128 19% A 64 11% A 42 5% A 130 17% A 30 6% R

Antimony 124 18% A 63 10% A 40 5% A 106 14% A 28 6% R

Arsenic 141 21% A 75 12% A 56 6% A 141 19% A 42 8% A

Barium 141 21% A 75 12% A 61 7% A 14 4 19% A 42 8% A

Beryllium 124 18% A 63 10% A 40 5% A 106 14% A 28 6% R

Boron 147 22% A 69 11% A 62 7% A 181 24% A 31 6% R

Cadmium 115 17% A 66 11% A 50 6% A 137 18% A 32 6% R

Chromium 115 17% A 66 11% A 42 5% A 137 18% A 32 6% R

Cobalt 124 18% A 63 10% A 40 5% A 106 14% A 28 6% R

Copper 141 21% A 75 12% A 57 7% A 141 19% A 42 8% A

Iron 151 22% A 79 13% A 56 6% A 172 23% A 42 8% A

Lead 141 21% A 75 12% A 48 6% A 141 19% A 42 8% A

Manganese 141 21% A 75 12% A 48 6% A 141 19% A 42 8% A

Mercu ry 51 7% A 12 2% T 21 2% T 52 7% A 18 4% T

Molybdenum 135 20% A 63 10% A 42 5% A 130 17% A 42 8% A

Nickel 50 7% A 38 6% A 27 3% R 63 8% A 17 3% T

Phosphorus 10 1% T 29 5% R 6 1% T 54 7% A 4 1% T

Silver 51 7% A 12 2% T 13 2% T 52 7% A 18 4% T

Strontium 124 18% A 63 10% A 40 5% A 106 14% A 28 6% R

T ABLE 39 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

Gonzal es Grimes Guadalupe Houston Karnes

Total wells 582 357 638 400 410

Aluminum 193 33% A 24 7% T 14 2% T 66 17% A 31 8% R

Antimony 192 33% A 24 7% T 14 2% T 63 16% A 27 7% R74

Arsenic 209 36% A 40 11 % A 17 3% T 82 21% A 40 10% A

Barium 209 36% A 41 11% A 17 3% T 82 21% A 40 10% A

Beryllium 192 33% A 24 7% T 14 2% T 64 16% A 27 7% R

Boron 293 50% A 48 13% A 30 5% R 68 17% A 81 20% A

Cadmium 206 35% A 33 9% R 17 3% T 79 20% A 32 8% R

Chromium 206 35% A 33 9% R 17 3% T 79 20% A 32 8% R

Cobalt 192 33% A 24 7% T 14 2% T 64 16% A 27 7% R

Copper 209 36% A 40 11% A 17 3% T 82 21% A 40 10% A

Iron 252 43% A 42 12% A 57 9% A 83 21% A 41 10% A

Lead 209 36% A 40 11% A 17 3% T 82 21% A 40 10% A

Ma nganese 217 37% A 40 11% A 17 3% T 82 21% A 40 10% A

Mercury 29 5% R 18 5% T 5 1% T 26 7% R 16 4% T

Molybdenum 193 33% A 24 7% T 14 2% T 66 17% A 37 9% R

Nickel 152 26% A 19 5% T 10 2% T 43 11% A 18 4% T

Phosphorus 116 20% A 2 1% T 5 1% T 32 8% R 5 1% T

Silver 27 5% R 18 5% T 5 1% T 20 5% T 16 4% T

Strontium 192 33% A 24 7% T 14 2% T 64 16% A 27 7% R

T ABLE 40 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

La Salle Lavaca Lee Leon Live Oak

Total wells 362 386 399 323 540

Aluminum 75 21% A 78 20% A 55 14% A 58 18% A 54 10% A

Antimony 70 19% A 78 20% A 49 12% A 54 17% A 49 9% A

Arsenic 89 25% A 95 25% A 57 14% A 73 23% A 75 14% A

Barium 89 25% A 95 25% A 57 14% A 73 23% A 75 14% A

Beryllium 70 19% A 78 20% A 49 12% A 54 17% A 49 9% A

Boron 116 32% A 91 24% A 129 32% A 56 17% A 72 13% A

Cadmium 88 24% A 76 20% A 55 14% A 72 22% A 62 11% A

Chromium 88 24% A 76 20% A 55 14% A 72 22% A 62 11% A

Cobalt 69 19% A 78 20% A 49 12% A 54 17% A 49 9% A

Copper 89 25% A 95 25% A 57 14% A 73 23% A 75 14% A

Iron 117 32% A 98 25% A 100 25% A 97 30% A 80 15% A

Lead 90 25% A 95 25% A 57 14% A 73 23% A 75 14% A

Manganese 89 25% A 95 25% A 68 17% A 74 23% A 76 14% A

Mercury 28 8% R 37 10% R 13 3% T 26 8% R 36 7% R

Molybdenum 74 20% A 78 20% A 55 14% A 56 17% A 54 10% A

Nickel 54 15% A 38 10% A 34 9% R 40 12% A 24 4% T

Phosphorus 33 9% R 1 0% T 22 6% T 29 9% R 0% T

Silver 28 8% R 37 10% R 13 3% T 25 8% T 36 7% R

Strontium 69 19% A 78 20% A 49 12% A 54 17% A 49 9% A75

T ABLE 41 N UMBER

, PERCE NT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

Madison Maverick McMullen Milam Robertson

Total wells 365 92 184 314 824

Aluminum 28 8% R 34 37% R 32 17% R 52 17% A 83 10% A

Antimony 28 8% R 7 8% T 32 17% R 52 17% A 72 9% A

Arsenic 37 10% R 35 38% R 45 24% A 53 17% A 85 10% A

Barium 37 10% R 36 39% R 45 24% A 53 17% A 85 10% A

Beryllium 28 8% R 7 8% T 32 17% R 5 2 17% A 72 9% A

Boron 33 9% R 17 18% T 48 26% A 80 25% A 182 22% A

Cadmium 34 9% R 35 38% R 41 22% A 53 17% A 78 9% A

Chromium 34 9% R 35 38% R 41 22% A 52 17% A 78 9% A

Cobalt 28 8% R 7 8% T 32 17% R 52 17% A 72 9% A

Copper 37 10% R 36 39% R 45 24% A 53 17% A 85 10% A

Iron 41 11% A 40 43% A 62 34% A 88 28% A 160 19% A

Lead 37 10% R 36 39% R 45 24% A 53 17% A 85 10% A

Manganese 37 10% R 36 39% R 45 24% A 65 21% A 96 12% A

Mercury 10 3% T 29 32% R 14 8% T 14 4% T 30 4% R

Molybdenum 28 8% R 34 37% R 32 17% R 52 17% A 83 10% A

Nickel 20 5% T 7 8% T 25 14% T 30 10% R 36 4% R

Phosphorus 13 4% T 5 5% T 12 7% T 25 8% T 14 2% T

Silver 5 1% T 29 32% R 14 8% T 14 4% T 30 4% R

Strontium 28 8% R 7 8% T 32 17% R 50 16% A 72 9% A

T ABLE 42 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR METALS

IN C OUNTIES

. A = A S NEEDED

, R = R ECOMMENDED

, T = T ESTING NEEDED

Washington Webb Wilson Wood Zav ala

Total wells 478 339 512 442 748

Aluminum 24 5% T 106 31% A 90 18% A 51 12% A 104 14% A

Antimony 24 5% T 77 23% A 73 14% A 33 7% R 92 12% A

Arsenic 42 9% A 120 35% A 96 19% A 54 12% A 114 15% A

Barium 42 9% A 117 35% A 96 1 9% A 55 12% A 114 15% A

Beryllium 24 5% T 77 23% A 73 14% A 35 8% R 92 12% A

Boron 41 9% A 105 31% A 131 26% A 52 12% A 153 20% A

Cadmium 33 7% R 102 30% A 93 18% A 49 11% A 110 15% A

Chromium 33 7% R 103 30% A 93 18% A 51 12% A 110 15% A

Cobalt 24 5% T 77 23% A 73 14% A 33 7% R 92 12% A

Copper 42 9% A 118 35% A 96 19% A 54 12% A 114 15% A

Iron 62 13% A 117 35% A 96 19% A 134 30% A 121 16% A76

Lead 42 9% A 117 35% A 96 19% A 52 12% A 114 15% A

Manganese 44 9% A 114 34% A 96 19% A 56 13% A 11 4 15% A

Mercury 21 4% T 47 14% A 37 7% R 25 6% T 49 7% A

Molybdenum 24 5% T 107 32% A 90 18% A 49 11% A 104 14% A

Nickel 18 4% T 63 19% A 38 7% A 21 5% T 39 5% A

Phosphorus 0% T 27 8% R 33 6% R 18 4% T 48 6% A

Silver 21 4% T 4 7 14% A 37 7% R 28 6% R 49 7% A

Strontium 24 5% T 77 23% A 73 14% A 33 7% R 92 12% A77



## Appendix XIII

– Radionuclides : number of samples

T ABLE 43 N UMBER OF RADIONUCLID E SAMPLES AVAILABLE IN THE TWDB GROUNDWATER DATABASE FOR

EACH COUNTY

.

County Total Wells Radium

- 226 and

Radium

- 228 Radon

222 Uranium Thorium Potassium

- 40

Atascosa 1117 20 25

Austin 321 13 13

Bastrop 791 13

Bee 631 5 1 5 1 1

Brazos 687 6 8

Burleson 847 3 8

Caldwell 599 3

Colorado 574 20 22

De Witt 513 6 5

Dimmit 527 9 16

Duval 683 38 4 39 4 4

Edwards 604 9 14

Fayette 863 4 6

Frio 756 17 21

Goliad 507 6 1 8 2 2

Gonzales 582 2 12

Grimes 357 2 2

Guadalupe 638 2

Houston 400 3 11

Karnes 410 9 4 6 3 3

La Salle 362 2 9

Lavaca 386 20 20

Lee 399 7

Leon 323 1 8

Live Oak 540 14 3 13 3 3

Madison 365 1 4

Maverick 92 11

McMullen 184 3

Milam 314 1 11

Robertson 824 18 26

Washington 478 3 3

Webb 339 21 13 25 1 6 16

Wilson 512 3 1 17

Wood 442 9

Zavala 748 14 27

Grand Total 18715 281 27 42178

T ABLE 4 4 N UMBER

, PERCENT OF TOTAL WATER WELLS

, AND GROUNDWATER TEST ING NEEDS FOR

RADIONUCLIDE PARTICL E EMI SSIONS IN E AGLE F ORD SHALE COUNTIES

. A = A S NEEDED

, R =

R ECOMMENDED

, T = T ESTING NEEDED

County Total W ells Alpha Beta

Atascosa 1117 41 4% A 40 4% A

Austin 321 26 8% R 13 4% T

Bastrop 791 21 3% T 13 2% T

Bee 631 1 6 3% T 12 2% T

Brazos 687 21 3% T 15 2% T

Burleson 847 20 2% T 17 2% T

Caldwell 599 4 1% T 4 1% T

Colorado 574 38 7% A 9 2% T

De Witt 513 17 3% T 12 2% T

Dimmit 527 36 7% R 33 6% R

Duval 683 6 6 10% A 18 3% T

Edwards 604 26 4% R 12 2% T

Fayette 863 20 2% T 18 2% T

Frio 756 34 4% R 34 4% R

Goliad 507 17 3% T 12 2% T

Gonzales 582 18 3% T 15 3% T

Grimes 357 18 5% T 16 4% T

Guadalupe 6 38 3 0% T 3 0% T

Houston 400 21 5% T 18 5% T

Karnes 410 18 4% T 13 3% T

La Salle 362 19 5% T 19 5% T

Lavaca 386 38 10% A 18 5% T

Lee 399 8 2% T 8 2% T

Leon 323 20 6% T 19 6% T

Live Oak 5 40 38 7% A 23 4% T

Madison 365 10 3% T 9 2% T

Maverick 92 28 30% R 28 30% R

McMullen 184 13 7% T 13 7% T

Milam 314 3 1% T 3 1% T

Robertson 824 40 5% A 22 3% T

Washington 478 21 4% T 18 4% T

Webb 339 25 7% T 22 6% T

Wilson 512 24 5% T 26 5% R

Wood 442 18 4% T 19 4% T

Zavala 748 28 4% R 22 3% T

Grand Total 18715 814 4% A 596 3% A79



## Appendix XIV

– PAH samples

T ABLE 45 N UMBER AND PERCENT OF SAM PLES OUT OF THE TOTA L NUMBER OF WATER WELLS IN EACH

COUNTY FOR PAH CONCENTRATIONS IN GR OUNDWATER

. Atascosa Bastrop Colorado

Dimmit Fayette Karnes La Salle Wilson Zavala

Total wells 1117 791 574 527 863 410 362 512 748

Percent 0.6% 0.4% 0.2% 4.7% 0.3% 0.2% 1.4% 0.2% 0.4%

Acenaphthene 7 3 1 25 3 1 5 1 3

Acenaphthylene 7 3 1 25 3 1 5 1 3

Anthracene 7 3 1 25 3 1 5 1 3

Benzo(a) anthracene 7 3 1 25 3 1 5 1 3

Benzo

- (a)

- pyrene 7 3 1 25 3 1 5 1 3

Benzo(b)fluoranthene 7 3 1 25 3 1 5 1 3

Benzo(ghi)perylene 7 3 1 25 3 1 5 1 3

Benzo(k)fluoranthene 7 3 1 25 3 1 5 1 3

Chrysene 7 3 1 25 3 1 5 1 3

Dibenzo (a,h) anthracene 7 25 1 5 1 3

Fluoranthene 7 3 1 25 3 1 5 1 3

Fluorene 7 3 1 25 3 1 5 1 3

Indeno (1,2,3

- cd) pyrene 7 3 1 25 3 1 5 1 3

Naphthalene 7 3 1 25 3 1 5 1 3

Phenanthrene 7 3 1 25 3 1 5 1 3

Pyrene 7 3 1 25 3 1 5 1 3