UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 WASHINGTON D.C. 20460

OFFICE OF THE ADMINISTRATOR

SCIENCE ADVISORY BOARD

August 4, 2011

EPA-SAB-11-012

The Honorable Lisa P. Jackson

Administrator

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W.

Washington, D.C. 20460

Subject: SAB Review of EPA’s Draft Hydraulic Fracturing Study Plan

Dear Administrator Jackson:

This Science Advisory Board (SAB) report responds to a request from EPA’s Office of Research 

and Development (ORD) to review and provide advice on its February 2011 Draft Plan to Study 

the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources (draft Study Plan). 

Hydraulic fracturing (HF) generates fractures in underground geologic formations to facilitate 

extraction of natural gas (or oil) from low-permeability formations in the subsurface. The 

process involves the use of directional drilling to drill vertically to the formation of interest and 

then horizontally into the formation. After installation of a wellbore which is subsequently 

perforated along its horizontal extent, water-based hydraulic fracturing fluid is injected and the 

formation is subjected to high pressure to induce fracturing. This method of natural gas 

extraction has the potential to impact ground and surface water resources through water 

acquisition, mixing with the fracking fluid chemicals, well injection of the fracking fluid, 

flowback and post-fracturing produced water, and water treatment and waste disposal.

The draft Study Plan identifies research questions and proposes a research program to assess

potential impacts of HF on drinking water resources and identify data gaps. The scope of the 

proposed research includes the full lifecycle of water in HF, from water acquisition through the 

mixing of chemicals and actual fracturing to the post-fracturing stage, including the management 

of flowback and produced water and its ultimate treatment and/or disposal. The SAB was asked 

to comment on the appropriateness of EPA’s proposed water lifecycle framework, research 

questions, and research approach, activities, and outcomes. 

In general, the SAB found EPA’s approach for the Study Plan to be appropriate and

comprehensive, and concludes that EPA has identified the necessary tools in its overall research 

approach to assess potential impacts of hydraulic fracturing on drinking water resources. EPA 
ii

identified specific potential outcomes for the research related to each step in the HF water 

lifecycle. However, the SAB does not anticipate that all of these outcomes can be achieved

given the time and cost constraints of the proposed research program. Further, the SAB 

identifies several areas of the Study Plan that can be better focused and suggests several 

additional important topics for further study to maximize impact within the time available until a 

report of interim research results is provided in 2012. 

The SAB concludes that while EPA’s use of the water lifecycle is an appropriate framework to 

characterize hydraulic fracturing and to identify potential impacts on drinking water, EPA should 

make certain adjustments to the framework, including consideration of water quantity impacts on 

the local watershed mass balance and consideration of the postclosure/well abandonment phase 

within the lifecycle. The SAB also finds that the Study Plan provides inadequate detail on how 

to address the overall research questions. EPA should develop more focused research questions 

that could be answered within the time and budget constraints of the project. 

To help focus efforts, the SAB recommends that EPA consider the four steps of the risk 

assessment paradigm (i.e., hazard identification, exposure assessment, dose-response assessment, 

and risk characterization) to assess and prioritize research activities for each water lifecycle stage 

presented in the draft Study Plan, and to focus research questions. The SAB recommends that 

EPA first focus on hazard identification and potential human exposure in the current research 

effort. The SAB concludes that important routes of potential human health exposure include 

exposure to liquids that are brought back to the surface during hydraulic fracturing operations 

and to potential groundwater contamination. EPA will be obtaining information as the study 

progresses and should use its expertise to set priorities for these and other pathways as needed. 

The SAB further recommends that none of the proposed comprehensive toxicity testing be 

conducted at this time due to time and cost constraints. Rather, EPA should evaluate available 

databases to understand the toxicity of selected constituents determined to have a high potential 

for exposure. 

The SAB has several additional suggestions to improve EPA’s draft Study Plan. EPA should 

specify whether the research focus is strictly on hydraulic fracturing in shale gas production or 

will include fracturing in conventional natural gas production, coal bed methane production, or 

other types of natural gas and oil extraction activity. SAB is not suggesting that studies be 

limited to particular type of activity; rather, EPA should be careful with the realm of inference

drawn in the report to different activities (i.e., results should not be generalized across all types 

of HF activity). EPA should also collect baseline hydrologic and water quality data in a given

case study area before HF activity begins so that significant changes in water availability or 

water quality caused by HF activity can be more readily documented. Furthermore, the Study 

Plan should address the cumulative consequences of carrying out multiple HF operations in a 

single watershed or region. 

In addition, EPA should gather currently available information on the composition of postfracturing produced water from the hydraulic fracturing process, and proprietary information on 

all additives included in any injected water. EPA should include the following constituents in 

EPA’s analysis of impacts of water acquisition and other HF processes on water quality: 

hydrogen sulfide, ammonium, radon, iron, manganese, arsenic, selenium, total organic carbon, 
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and bromide, in addition to HF fluid constituents and formation chemicals. Further, EPA should 

assess the potential of constituents in HF-impacted waters to form disinfection by-products 

during drinking water treatment.

EPA should also include consideration of water quality parameters for which Maximum 

Contaminant Levels (MCLs) have not been established under the Safe Drinking Water Act, in 

addition to the proposed parameters for which MCLs have been established. Since MCLs have 

not been established for some of the chemicals used in the HF process, MCLs alone will not be 

sufficient for assessing all potentially significant impacts of hydraulic fracturing on drinking 

water quality. EPA should focus study of treatment of post-fracturing produced water 

constituents on literature searches of municipal and industrial wastewater management practices 

with similar waters, and assess the need for any special storage, handling, management, or 

disposal controls for solid residuals after treatment. 

Lastly, EPA should develop one or more focused research outcomes related to the planned 

research pertaining to environmental justice issues. For the case studies, EPA should also assess 

demographic information, such as race, color, national origin, and income, to screen whether 

hydraulic fracturing disproportionately impacts some citizens near sites used for the case studies 

(e.g., identify whether more HF wells are near communities with lower incomes). 

The SAB appreciates the opportunity to provide EPA with advice on this important subject. We 

look forward to receiving the Agency’s response and to providing future advice on this topic.

Sincerely,

/signed/ /signed/

Dr. Deborah L. Swackhamer, Chair Dr. David A. Dzombak, Chair

Science Advisory Board SAB Hydraulic Fracturing Study Plan

Review Panel 

Enclosures
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NOTICE

This report has been written as part of the activities of the EPA Science Advisory Board (SAB), 

a public advisory group providing extramural scientific information and advice to the 

Administrator and other officials of the Environmental Protection Agency. The SAB is 

structured to provide balanced, expert assessment of scientific matters related to problems facing 

the Agency. This report has not been reviewed for approval by the Agency and, hence, the 

contents of this report do not necessarily represent the views and policies of the Environmental 

Protection Agency, nor of other agencies in the Executive Branch of the Federal government, nor 

does mention of trade names of commercial products constitute a recommendation for use. 

Reports of the SAB are posted on the EPA Web Site at http://www.epa.gov/sab. 
v

U.S. Environmental Protection Agency

Science Advisory Board

HYDRAULIC FRACTURING REVIEW PANEL 

CHAIR

Dr. David A. Dzombak, Walter J. Blenko Sr. Professor of Environmental Engineering, 

Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, 

PA

PANEL MEMBERS

Dr. George Alexeeff, Acting Director, Office of Environmental Health Hazard Assessment, 

California Environmental Protection Agency, Oakland, CA

Dr Tom Ballestero, Professor, Civil Engineering, University of New Hampshire, Durham, NH

Dr. Mark Benjamin, Professor, Department of Civil and Environmental Engineering, 

University of Washington, Seattle, WA

Dr. Michel Boufadel, Professor of Environmental Engineering, Civil and Environmental 

Engineering, College of Engineering, Temple University, Philadelphia, PA

Dr. Elizabeth Boyer, Associate Professor, School of Forest Resources, Pennsylvania State 

University, University Park, PA

Mr. David Burnett, Directory of Technology, GPRI, Department of Petroleum Engineering, 

Look College of Engineering, Texas A&M University, College Station, TX

Dr. Thomas L. Davis, Professor, Department of Geophysics, Colorado School of Mines, 

Golden, CO

Dr. Shari Dunn-Norman, Professor, Geological Sciences and Engineering, Missouri University 

of Science and Technology, Rolla, MO

Dr. John P. Giesy, Professor and Canada Research Chair, Veterinary Biomedical Sciences and 

Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Dr. Jeffrey Griffiths, Associate Professor, Department of Public Health and Community 

Medicine, School of Medicine, Tufts University, Boston, MA

Dr. Philip Gschwend, Professor, Civil and Environmental Engineering, Massachusetts Institute 

of Technology, Cambridge, MA

Dr. Cynthia M. Harris, Director and Professor, Institute of Public Health, Florida A&M 

University, Tallahassee, FL
vi

Dr. Nancy K. Kim, Senior Executive, Health Research, Inc., Troy, NY

Dr. Cindy M. Lee, Professor, Department of Environmental Engineering and Earth Sciences, 

Clemson University, Anderson, SC

Dr. Duncan Patten, Research Professor, Hydroecology Research Program, Department of Land 

Resources and Environmental Sciences, Montana State University, Bozeman, MT

Dr. Stephen Randtke, Professor, Department of Civil, Environmental, and Architectural 

Engineering, University of Kansas, Lawrence, KS

Dr. Danny Reible, Professor, Department of Civil, Architectural and Environmental 

Engineering, University of Texas, Austin, TX

Dr. Connie Schreppel, Director of Water Quality, Mohawk Valley Water Authority, Utica, NY

Dr. Geoffery Thyne, Sr. Research Scientist, Enhanced Oil Recovery Institute, University of 

Wyoming, University of Wyoming, Laramie, WY

Dr. Jeanne VanBriesen, Professor, Civil and Environmental Engineering, Carnegie Mellon 

University, Pittsburgh, PA

Dr. Radisav Vidic, Professor and Chairman, Civil and Environmental Engineering, University 

of Pittsburgh, Pittsburgh, PA

SCIENCE ADVISORY BOARD STAFF

Mr. Edward Hanlon, Designated Federal Officer, U.S. Environmental Protection

Agency, Science Advisory Board Staff, Washington, DC
vii

U.S. Environmental Protection Agency

Science Advisory Board

CHAIR

Dr. Deborah L. Swackhamer, Professor and Charles M. Denny, Jr. Chair in Science, 

Technology and Public Policy, Hubert H. Humphrey School of Public Affairs and Co-Director of 

the Water Resources Center, University of Minnesota, St. Paul, MN

SAB MEMBERS

Dr. David T. Allen, Professor, Department of Chemical Engineering, University of Texas, 

Austin, TX

Dr. Claudia Benitez-Nelson, Full Professor and Director of the Marine Science Program, 

Department of Earth and Ocean Sciences , University of South Carolina, Columbia, SC

Dr. Timothy J. Buckley, Associate Professor and Chair, Division of Environmental Health 

Sciences, College of Public Health, The Ohio State University, Columbus, OH

Dr. Patricia Buffler, Professor of Epidemiology and Dean Emerita, Department of 

Epidemiology, School of Public Health, University of California, Berkeley, CA

Dr. Ingrid Burke, Director, Haub School and Ruckelshaus Institute of Environment and Natural 

Resources, University of Wyoming, Laramie, WY

Dr. Thomas Burke, Professor, Department of Health Policy and Management, Johns Hopkins 

Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD

Dr. Terry Daniel, Professor of Psychology and Natural Resources, Department of Psychology, 

School of Natural Resources, University of Arizona, Tucson, AZ

Dr. George Daston, Victor Mills Society Research Fellow, Product Safety and Regulatory 

Affairs, Procter & Gamble, Cincinnati, OH

Dr. Costel Denson, Managing Member, Costech Technologies, LLC, Newark, DE

Dr. Otto C. Doering III, Professor, Department of Agricultural Economics, Purdue University, 

W. Lafayette, IN

Dr. David A. Dzombak, Walter J. Blenko, Sr. Professor of Environmental Engineering, 

Department of Civil and Environmental Engineering, College of Engineering, Carnegie Mellon 

University, Pittsburgh, PA

Dr. T. Taylor Eighmy, Vice President for Research, Office of the Vice President for Research, 

Texas Tech University, Lubbock, TX
viii

Dr. Elaine Faustman, Professor and Director, Institute for Risk Analysis and Risk 

Communication, School of Public Health, University of Washington, Seattle, WA

Dr. John P. Giesy, Professor and Canada Research Chair, Veterinary Biomedical Sciences and 

Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Dr. Jeffrey K. Griffiths, Professor, Department of Public Health and Community Medicine, 

School of Medicine, Tufts University, Boston, MA

Dr. James K. Hammitt, Professor, Center for Risk Analysis, Harvard University, Boston, MA

Dr. Bernd Kahn, Professor Emeritus and Associate Director, Environmental Radiation Center, 

Georgia Institute of Technology, Atlanta, GA

Dr. Agnes Kane, Professor and Chair, Department of Pathology and Laboratory Medicine, 

Brown University, Providence, RI

Dr. Madhu Khanna, Professor, Department of Agricultural and Consumer Economics, 

University of Illinois at Urbana-Champaign, Urbana, IL

Dr. Nancy K. Kim, Senior Executive, Health Research, Inc., Troy, NY

Dr. Kai Lee, Program Officer, Conservation and Science Program, David & Lucile Packard 

Foundation, Los Altos, CA (Affiliation listed for identification purposes only)

Dr. Cecil Lue-Hing, President, Cecil Lue-Hing & Assoc. Inc., Burr Ridge, IL

Dr. Floyd Malveaux, Executive Director, Merck Childhood Asthma Network, Inc., Washington, 

DC

Dr. Lee D. McMullen, Water Resources Practice Leader, Snyder & Associates, Inc., Ankeny, 

IA

Dr. Judith L. Meyer, Professor Emeritus, Odum School of Ecology, University of Georgia, 

Lopez Island, WA

Dr. James R. Mihelcic, Professor, Civil and Environmental Engineering, University of South 

Florida, Tampa, FL

Dr. Jana Milford, Professor, Department of Mechanical Engineering, University of Colorado, 

Boulder, CO

Dr. Christine Moe, Eugene J. Gangarosa Professor, Hubert Department of Global Health, 

Rollins School of Public Health, Emory University, Atlanta, GA
ix

Dr. Horace Moo-Young, Dean and Professor, College of Engineering, Computer Science, and 

Technology, California State University, Los Angeles, CA

Dr. Eileen Murphy, Grants Facilitator, Ernest Mario School of Pharmacy, Rutgers University, 

Piscataway, NJ

Dr. Duncan Patten, Research Professor, Hydroecology Research Program, Department of Land 

Resources and Environmental Sciences, Montana State University, Bozeman, MT

Dr. Stephen Polasky, Fesler-Lampert Professor of Ecological/Environmental Economics, 

Department of Applied Economics, University of Minnesota, St. Paul, MN

Dr. Arden Pope, Professor, Department of Economics, Brigham Young University, Provo, UT

Dr. Stephen M. Roberts, Professor, Department of Physiological Sciences, Director, Center for 

Environmental and Human Toxicology, University of Florida, Gainesville, FL

Dr. Amanda Rodewald, Professor of Wildlife Ecology, School of Environment and Natural 

Resources, The Ohio State University, Columbus, OH

Dr. Jonathan M. Samet, Professor and Flora L. Thornton Chair, Department of Preventive 

Medicine, University of Southern California, Los Angeles, CA

Dr. James Sanders, Director and Professor, Skidaway Institute of Oceanography, Savannah, 

GA

Dr. Jerald Schnoor, Allen S. Henry Chair Professor, Department of Civil and Environmental 

Engineering, Co-Director, Center for Global and Regional Environmental Research, University 

of Iowa, Iowa City, IA

Dr. Kathleen Segerson, Philip E. Austin Professor of Economics , Department of Economics, 

University of Connecticut, Storrs, CT

Dr. Herman Taylor, Director, Principal Investigator, Jackson Heart Study, University of 

Mississippi Medical Center, Jackson, MS

Dr. Barton H. (Buzz) Thompson, Jr., Robert E. Paradise Professor of Natural Resources Law 

at the Stanford Law School and Perry L. McCarty Director, Woods Institute for the 

Environment, Stanford University, Stanford, CA

Dr. Paige Tolbert, Professor and Chair, Department of Environmental Health, Rollins School of 

Public Health, Emory University, Atlanta, GA

Dr. John Vena, Professor and Department Head, Department of Epidemiology and Biostatistics, 

College of Public Health, University of Georgia, Athens, GA
x

Dr. Thomas S. Wallsten, Professor and Chair, Department of Psychology, University of 

Maryland, College Park, MD

Dr. Robert Watts, Professor of Mechanical Engineering Emeritus, Tulane University, 

Annapolis, MD

Dr. R. Thomas Zoeller, Professor, Department of Biology, University of Massachusetts, 

Amherst, MA

SCIENCE ADVISORY BOARD STAFF

Dr. Angela Nugent, Designated Federal Officer, U.S. Environmental Protection Agency, 

Washington, DC
xi

Table of Contents

1. EXECUTIVE SUMMARY................................................................................................................................1

2. INTRODUCTION............................................................................................................................................11

2.1. BACKGROUND ...........................................................................................................................................11

2.2. CHARGE QUESTIONS TO THE PANEL..........................................................................................................12

3. RESPONSE TO THE CHARGE QUESTIONS............................................................................................14

3.1. WATER USE IN HYDRAULIC FRACTURING.................................................................................................14

3.2. RESEARCH QUESTIONS..............................................................................................................................16

3.3. RESEARCH APPROACH ..............................................................................................................................25

3.4. PROPOSED RESEARCH ACTIVITIES - WATER ACQUISITION........................................................................35

3.5. PROPOSED RESEARCH ACTIVITIES - CHEMICAL MIXING ...........................................................................39

3.6. PROPOSED RESEARCH ACTIVITIES - WELL INJECTION...............................................................................43

3.7. PROPOSED RESEARCH ACTIVITIES – FLOWBACK AND PRODUCED WATER................................................49

3.8. PROPOSED RESEARCH ACTIVITIES - WASTEWATER TREATMENT AND WASTE DISPOSAL .........................52

3.9. RESEARCH OUTCOMES..............................................................................................................................56

APPENDIX A: EPA’S CHARGE TO THE PANEL.......................................................................................... A-1

APPENDIX B: TABLE 2 FROM EPA’S FEBRUARY 2011 DRAFT HYDRAULIC FRACTURING 

STUDY PLAN..........................................................................................................................................................B-1

APPENDIX C: FIGURE 7 FROM EPA’S FEBRUARY 2011 DRAFT HYDRAULIC FRACTURING 

STUDY PLAN......................................................................................................................................................... C-1

APPENDIX D: FIGURES 9A AND 9B FROM EPA’S FEBRUARY 2011 DRAFT HYDRAULIC 

FRACTURING STUDY PLAN............................................................................................................................. D-1
xii

Abbreviations and Acronyms 

BMP Best Management Practices

BTEX Benzene, Toluene, Ethylbenzene, and Xylenes

CWT Centralized Waste Treatment

CWA Clean Water Act

DOE U.S. Department of Energy

DBP Disinfection By-product

EPA U.S. Environmental Protection Agency

HF Hydraulic Fracturing

MCLs Maximum Contaminant Levels

NETL DOE’s National Energy Technology Laboratory

O&M Operation & Maintenance

ORD EPA Office of Research and Development

POTW Publicly Owned Treatment Works

PPRTVs Provisional Peer-Reviewed Toxicity Values 

PWSS Public Water Supply Systems

QSAR Quantitative Structure-Activity Relationships

Rn Radon

SAB EPA Science Advisory Board

TDS Total Dissolved Solids

TOC Total Organic Carbon

UIC Underground Injection Control

USDW Underground Sources of Drinking Water

USGS U.S. Geological Survey
1

EXECUTIVE SUMMARY

In January 2010, EPA’s Office of Research and Development (ORD) initiated planning for a 

study to assess the potential impacts of hydraulic fracturing on drinking water resources. EPA 

proposed a study scope in March 2010 that was reviewed by the Science Advisory Board (SAB) 

in an open meeting on April 7-8, 2010; SAB’s Report on its review of the study scope was 

transmitted to the Administrator on June 24, 2010. Subsequently, EPA developed a draft 

Hydraulic Fracturing Study Plan and requested SAB review of the draft Plan. The charge 

questions for the review are provided in Appendix A. The SAB Hydraulic Fracturing Review 

Panel reviewed the draft Study Plan and background materials provided by ORD, considered 

public comments that were received on the draft Study Plan, held public meetings on March 7-8, 

2011, and held public teleconferences on May 19 and May 25, 2011 to provide advice to EPA on 

the scientific adequacy, suitability and appropriateness of EPA’s draft Study Plan. The Panel 

also considered oral statements that were received on the draft Study Plan during the public 

meetings and teleconferences. The external draft SAB Report on EPA’s Draft Hydraulic 

Fracturing Study Plan dated June 14, 2011 was reviewed and approved by the Chartered SAB at 

a public teleconference on July 5, 2011. 

The draft Study Plan assesses the potential impacts of hydraulic fracturing on drinking water 

resources, and identifies the driving factors that affect the severity and frequency of any potential 

impacts. A summary of the research questions upon which the draft Study Plan was formulated 

is provided in Appendix B (Table 2 from the Study Plan). The draft Study Plan proposes to 

assess potential impacts from five aspects of the water lifecycle associated with hydraulic 

fracturing: Water Acquisition, Chemical Mixing, Well Injection, Flowback and Produced Water, 

and Water Treatment and Waste Disposal. As noted in the draft Study Plan, EPA plans to 

conduct this lifecycle analysis through literature reviews, data gathering and analysis, modeling, 

laboratory investigations, and field investigations and case studies.

The SAB was asked to comment on various aspects of EPA’s Study Plan, including EPA’s 

proposed water lifecycle framework for the study plan, EPA’s proposed research questions that 

would address whether or not hydraulic fracturing impacts drinking water resources, and EPA’s 

proposed research approach, activities, and outcomes. The enclosed report provides the advice 

and recommendations of the SAB through the efforts of the SAB Hydraulic Fracturing Review 

Panel. 

In general, the SAB found EPA’s overall approach for the draft EPA Study Plan to be 

appropriate and comprehensive, and concludes that EPA has identified the necessary tools in its 

overall research approach to assess adequately potential impacts of hydraulic fracturing on 

drinking water resources. However, the SAB identified several areas of the Study Plan that can 

be better focused and recommends several additional important topics for study to maximize

impact within the time available until a report of interim research results is provided in 2012. 

While a more detailed description of the technical recommendations is included in this SAB 

Report, the key points and recommendations are highlighted below. 
2

Charge Question 1: Water Use in Hydraulic Fracturing

EPA has developed a Study Plan that identifies a set of proposed research activities associated 

with each stage of the hydraulic fracturing water lifecycle, from water acquisition through the 

mixing of chemicals and actual fracturing to post-fracturing production, including the 

management of post-fracturing produced water and ultimate treatment and disposal. 

The SAB concludes that EPA’s use of the water lifecycle depicted in Figure 7 of the draft Study 

Plan is an appropriate framework to characterize hydraulic fracturing and to identify the potential 

drinking water issues. Figure 7 is provided within this SAB report as Appendix C. The SAB 

also finds that the Study Plan adequately identifies and addresses the areas of concern identified 

for each stage of the hydraulic fracturing water lifecycle. However, the SAB concludes that the 

diagram is incomplete, and has several recommendations to strengthen the framework and 

provide an improved assessment of potential drinking water issues. 

The SAB recommends that EPA make certain adjustments to the hydraulic fracturing lifecycle 

framework. EPA should assess water quantity impacts on the local watershed mass balance, and 

the framework depicted in Figure 7 should link water fluxes associated with hydraulic fracturing 

to water flows in the surrounding natural hydrological cycle. The water mass balance that 

accounts for waters entering and leaving the system is a critical issue, and EPA should initially 

focus the water mass balance assessment towards the case study efforts. EPA should also assess 

interbasin transfers of post-fracturing produced water in order to identify possible water quality 

and quantity issues associated with such transfers. 

The SAB recommends that EPA also add a postclosure/well abandonment phase as a new 

component to Figure 7, and separately consider this phase in the Study Plan. SAB recognizes 

that potential risks for this new component may not be at the same level as potential risks in 

other phases of the lifecycle. EPA should determine if there is historical evidence to indicate if 

there are any differences regarding the postclosure/well abandonment phase of hydraulic 

fracturing wells when compared to the postclosure/well abandonment phase for other types of 

wells. 

In addition to the water quality impacts indicated in Figure 9a, EPA should assess the potential 

release of volatile contaminants to the air, and their potential for subsequent deposition to surface 

water resources. Figure 9a is provided within this SAB report as Appendix D. 

Charge Question 2: Research Questions

EPA has identified a comprehensive set of research questions to address the primary mechanisms 

and pathways that can allow hydraulic fracturing to impact drinking water resources (see 

Appendix B). The questions cover each step of the life cycle of a hydraulic fracturing process 

that can impact drinking water and are appropriately focused on the unique aspects of hydraulic 

fracturing that can lead to such impacts. EPA also proposes to conduct scenario evaluations that 

will assess the environmental futures and impacts of hydraulic fracturing operations at various 

spatial and temporal scales in the selected case study areas. The scenarios will include at least 

two futures: (1) average annual conditions in 10 years based on the full exploitation of non-
3

conventional natural gas and (2) average annual conditions in 10 years based on sustainable 

water use in hydraulic fracturing operations. 

As presented by EPA staff at the March 7, 2011 SAB meeting, EPA’s budget for the research on 

HF impacts to drinking water resources is as follows:

Fiscal Year 2010 (Enacted): $1.9 million.

Fiscal Year 2011 (President’s Request): $4.4 million.

Fiscal Year 2012 (President’s Request): $6.1 million.

EPA’s schedule for delivery of research products includes completion of a report of interim 

research results in 2012. This interim report will contain a synthesis of EPA’s research to date 

and will include results from retrospective case studies and initial results from scenario 

evaluations. Since certain portions of the work described in the draft Study Plan, including 

prospective case studies and work performed under EPA’s Science to Achieve Results (STAR) 

program, are longer-term activities that are not likely to be finished by 2012, additional reports 

of study findings will be published as these long-term activities progress, with a follow-up report 

on the study in 2014.

EPA’s use of retrospective case studies will focus on investigating reported instances of drinking 

water resource contamination or other impacts in areas where hydraulic fracturing has already 

occurred. EPA will conduct retrospective case studies at three to five sites across the United 

States; these studies will use existing data and possibly field sampling, modeling, and/or parallel 

laboratory investigations to determine the potential relationship between reported impacts and 

hydraulic fracturing activities. EPA will also conduct prospective case studies that will involve 

sites where hydraulic fracturing will occur after the research is initiated. These case studies 

allow sampling and characterization of the site before, during, and after water extraction, 

drilling, hydraulic fracturing fluid injection, flowback, and gas production. EPA will work with 

industry and other stakeholders to conduct two to three prospective case studies in different 

regions of the United States. 

The SAB finds that the Study Plan provides inadequate detail on how to address the overall 

research questions presented in Table 2 (see Appendix B) and that EPA should develop more 

focused research questions that could be answered within the budget and time constraints of the 

project. The SAB provides recommendations for supplementing and revising the existing 

questions. These recommendations are designed to recognize explicitly key issues that may not 

be adequately addressed in the current questions. The SAB also finds that the scenario 

evaluation does not, but should, cross all research questions. For example, the potential effects 

of water acquisition on drinking water quality are not included in scenario evaluation. SAB also 

notes that scenario evaluations beyond the case studies for water acquisition and flowback water, 

and their modeling, would particularly assist EPA’s research effort. 

SAB recommends that EPA clarify whether the research focus is on hydraulic fracturing in shale 

gas production, conventional natural gas production, coal bed methane production, and/or other 

types of hydraulic fracturing activity. SAB is not suggesting that studies be limited to particular 

type of activity; rather, EPA should be careful with the realm of inference drawn in the report to 

different activities (i.e., results should not be generalized across all types of HF activity). In 
4

addition, to the extent that the Study Plan is being designed to inform decision-making related to 

an EPA regulatory framework, the Study Plan should include specific research questions aimed 

at this objective. 

Within the body of this Report, SAB provides comments that may affect the primary and 

secondary research questions and how they are answered at each life cycle stage. An important 

challenge facing the study is the diverse nature of hydraulic fracturing operations around the 

country. The geological setting, the hydrological setting, the community setting and the 

requirements and standard operating procedures at each stage of the hydraulic fracturing life 

cycle vary with geographical location. These differences can give rise to fundamental 

differences in the nature of the potential impacts to drinking water resources. The SAB 

recommends that EPA include several focused research questions associated with individual 

lifecycle stages. The SAB also concludes that the Study Plan should address the cumulative 

consequences of carrying out multiple HF operations in a single watershed or region. While 

detailed research on cumulative impacts may be beyond the scope of the current study, the 

incremental impacts of hydraulic fracturing operations should be well characterized in the 

current study and a framework for assessment of cumulative impacts should be established. This 

will provide the foundation for subsequent assessment of total environmental exposures and 

risks, and cumulative impacts. 

The SAB recommends that EPA consider the four steps of the risk assessment paradigm (i.e., 

hazard identification, exposure assessment, dose-response assessment, and risk characterization) 

to assess and prioritize research activities for each water lifecycle stage presented in the draft 

Study Plan, and to focus research questions. At this time, EPA should focus on hazard 

identification and potential human exposure for the components of HF fluids in the current 

research effort. The SAB strongly recommends that none of the proposed toxicity testing of 

chemical constituents be conducted at this time due to time and cost constraints. Rather, EPA 

should evaluate the toxicity of selected constituents determined to have a high potential for 

exposure through literature sources and available databases. The SAB recommends that EPA 

explicitly recognize this in the framing of the secondary research questions. 

The SAB does not agree that developing analytical methods for detecting chemicals associated 

with HF is an appropriate goal for the research. The SAB concludes that it may be difficult to 

develop analytical methods for specific constituents that do not have existing EPA-approved 

methods, and difficult to achieve a practical indicator approach, within the time and budget 

allotted for the study. If it is undertaken, such an effort could succeed for a limited number of 

chemicals, but at the cost of diverting resources from goals that should have higher priority. 

SAB recommends that EPA conduct research in a few additional areas. EPA should assess the 

capacity of microseismic data to provide detailed information about extent of fracturing and to 

assist in the hydraulic fracturing modeling (see discussion under Charge Question 4c). In 

addition, potential impacts to drinking water may be the result of the hydraulic fracturing process

or the result of the manner in which it is implemented (e.g., the particular manner in which site 

preparation and drilling are conducted). Potential impacts to drinking water resources that are 
5

the result of particular management practices should be identified as being linked to those 

management practices. This would be most useful if there are sufficient data available to 

compare various management practices. 

The SAB recommends EPA include both prospective and retrospective case studies as planned 

because the studies address different questions and perspectives. In retrospective case studies 

there is concern that it may not be possible to obtain sufficient data to separate risks that may be 

associated with the various management practices employed. 

In prospective case studies there is concern that the best management practices examined in these 

case studies will not necessarily be used at other sites, and that the water quality parameters that 

are analyzed before, during, and after injection of the HF fluids will probably undergo minimal 

change during the relatively short duration of the research program. Also, the number of 

retrospective and prospective case studies that can be evaluated in the given time will be limited, 

which will make it difficult to generalize from the data gathered. The SAB recommends that 

EPA take a long view, and consider what kind of data will be desired in ten years in order to 

design the data collection protocols for the prospective studies. Further, the SAB notes that the 

selected case study locations must be chosen based on reasonable, mechanistically possible 

contamination scenarios, incorporating uncertainty.

An additional issue is that EPA needs to view the environmental concerns and issues in the 

context of the local community. As noted in Section 9 of the Study Plan, to address these 

concerns, EPA plans to combine the data collected on the locations of well sites within the 

United States with demographic information (e.g., income and race) to screen whether hydraulic 

fracturing disproportionately impacts some citizens and to identify areas for further study. The 

SAB concludes this would effectively inform environmental justice discussions. The SAB 

recommends that EPA consider information such as race, color, national origin, and income in 

this analysis, identify metrics that would gauge the environmental justice impacts resulting from 

this analysis, and develop one or more specific research outcomes related to the planned research 

pertaining to environmental justice issues. For the case studies, EPA should also assess 

demographic information, such as race, color, national origin, and income, to screen whether 

hydraulic fracturing disproportionately impacts some citizens near sites used for the case studies 

(e.g., identify whether more HF wells are near communities with lower incomes). Also, EPA 

should conduct systematic interviews with local public health officers to identify potentially 

vulnerable subpopulations, the consideration of fairness in local decision-making, and the 

impacts of current operations associated with HF operations at case study locations. 

Another issue is the importance of assessing uncertainty at each step in the research study. 

Given time and resource constraints, the studies will not be able to answer all questions with a 

high degree of certainty. The SAB recommends that EPA explicitly identify or estimate the 

uncertainty or confidence in all research conclusions, and in the assessment of cause and effect 

associated with potential HF impacts to drinking water supplies. The quality of the information 

on which the research was based as well as any uncertainties arising in the conduct of the 

research should be evaluated, at least in a preliminary manner.
6

The SAB has a number of specific concerns associated with the research questions at individual 

lifecycle stages. These are presented in the discussion associated with the subsequent charge 

questions. 

Charge Question 3: Research Approach

EPA’s research approach involves application of a broad range of scientific expertise in 

environmental and petroleum engineering, ground water hydrology, fate and transport modeling, 

and toxicology, as well as many other areas, and use of case studies and generalized scenario 

evaluations, to address the key questions associated with each of the five water cycle stages of 

hydraulic fracturing. 

The SAB agrees that EPA has identified the necessary tools in its overall research approach as 

outlined in the Study Plan to adequately assess potential impacts of hydraulic fracturing on 

drinking water resources. However, the SAB concludes that EPA should conduct a well-focused 

study so that critical research questions are identified, approaches are designed that will enable 

answering those questions, and conclusions reached are supported by appropriate analysis. 

The SAB finds that the Study Plan provides limited detail on anticipated data acquisition, 

analysis, management, and storage (including model simulation results), and recommends that 

EPA revise the draft Study Plan to include such details. The SAB recommends that EPA 

consider using existing data acquisition and analysis methods rather than develop new methods 

due to time and budget constraints. EPA should also carefully consider the quality of various 

types of data that would be used within the analysis (industry data, local and non-industry data), 

and consider archiving samples for later use.

The SAB finds that the Study Plan overemphasizes case studies in the study approach, and 

underemphasizes the review and analysis of existing data and the use of scenario analysis. The 

SAB concludes that the specific objectives of case studies are unclear and should be clarified, 

and that EPA should explain better the rationale for the selected case studies. The SAB 

concludes there is significant value to the synthesis of existing data, and that EPA should review 

all available data sources to learn from what is already known about the relationship of hydraulic 

fracturing and drinking water resources. The SAB also provides citations for additional literature 

that EPA should assess in order to ensure a comprehensive understanding of the trends in the 

hydraulic fracturing process and the potential impacts of hydraulic fracturing on drinking water 

resources.

Charge Question 4(a): Proposed Research Activities - Water Acquisition

To address the research questions listed in Table 2 (see Appendix B) for the Water Acquisition 

stage of the water lifecycle, EPA plans to conduct retrospective and prospective case studies, 

analyze and map water quality and quantity data, and assess impacts of cumulative water 

withdrawals. The SAB finds that these proposed activities will, in general, adequately address 

the research questions associated with this lifecycle stage as outlined in Table 2. However, the 

SAB recommends that the Study Plan include an additional research effort to collect baseline 
7

hydrologic and water quality data in a given area before HF activity begins, so that significant 

changes in water availability or water quality caused by HF activity can be more readily 

documented. 

SAB also recommends that EPA consider developing a “vulnerability index” or a list of criteria 

that could be used to indicate situations where a water supply is vulnerable to adverse impacts on 

water quality or quantity, and where further evaluation may be warranted. SAB recognizes that, 

given EPA’s limits on available time and site-specific data, this activity could potentially be 

delayed until there is more experience and available data.

The SAB recommends that EPA’s list of analytes (provided in Table G1 of the draft Study Plan) 

that would be studied to assess the potential impacts of water acquisition and other HF activities 

on water quality should specifically include the following constituents: hydrogen sulfide, 

ammonium, radon, iron, manganese, arsenic, selenium, total organic carbon, and bromide, in 

addition to HF fluid constituents and likely formation or additive chemicals. EPA should also 

assess the potential of constituents in HF-impacted waters to form disinfection by-products 

(including trihalomethanes, haloacetic acids, total organic halogen, and other halogenated 

organic compounds) in drinking water treatment. 

The SAB recommends that EPA include consideration of HF water quality parameters for which 

Maximum Contaminant Levels (MCLs) have not been established under the Safe Drinking 

Water Act, in addition to the proposed parameters for which MCLs have been established. Since 

MCLs have not been established for some of the chemicals used in the HF process, MCLs alone 

will not be sufficient for assessing all potentially significant impacts of hydraulic fracturing on 

drinking water quality. EPA should also examine trends in water quality associated with HF 

water acquisition and determine whether adverse impacts will result if these trends continue. 

Advances in membrane desalination, increasing use of aquifer storage and recovery systems, and 

regional water shortages are changing perspectives on what constitutes a source of drinking 

water. The SAB recommends that EPA not automatically exclude from consideration potential 

impacts on a water source having more than 10,000 mg/L of total dissolved solids if it could 

reasonably be anticipated to be a viable source of water supply in the future.

Charge Question 4(b): Proposed Research Activities - Chemical Mixing

The SAB concludes that, overall, EPA has generally proposed a sound approach to address the 

research questions associated with this lifecycle stage as outlined in Table 2 (see Appendix B). 

The SAB has some recommendations for specific components of the research plan that could be 

strengthened as described further below.

SAB recommends that EPA gather both currently available information on the composition of 

post fracturing produced water from the hydraulic fracturing process, and proprietary 

information on all additives included in any injected water. The SAB supports EPA’s proposed 

approach to analyze existing data rather than collect samples to assess HF fluid composition and 

toxicity of fluid components, and concludes that EPA’s effort to gather data from nine hydraulic 

fracturing service companies will likely provide sufficient information on the composition of HF 
8

fluids. SAB recommends that EPA also gather HF fluid composition data from states collecting 

such data, and consider the role that recycling and reuse of HF fluids will play in influencing 

both quantity and composition of HF fluids. Also, while it would be helpful if EPA developed 

indicators of contamination, it may be difficult to achieve a practical indicator approach within 

the time allotted for the current study. 

SAB generally supports EPA’s plans to identify factors that influence the likelihood of 

contamination of drinking water resources as a result of chemical mixing activities. Although 

SAB agrees that EPA will identify a number of factors that influence the likelihood of 

contamination of drinking water resources as a result of chemical mixing activities, the list of 

factors may not be complete, the project time and budget may not allow time for a complete 

evaluation of the factors, and the results should not be generalized across all HF sites. 

SAB does not conclude that case studies alone will provide sufficient information regarding 

effectiveness of mitigation approaches in reducing impacts to drinking water resources. SAB 

recommends that EPA analyze data from HF service companies and states in order to provide 

additional insight. The retrospective case studies may also be a source of useful information 

about approaches that failed to prevent or control impacts. 

Charge Question 4(c): Proposed Research Activities - Well Injection

With the cooperation of service companies, full access to data, and careful selection of case 

studies, the SAB agrees that the proposed research can adequately address several fundamental 

questions associated with possible impacts of the injection and fracturing processes on drinking 

water resources. However, the SAB concludes it will not be possible to cover all facets of the 

proposed research within the time allotted for the research activities, and recommends that EPA 

narrow the scope of activities associated with specific case studies and site investigations and use 

a wide variety of sources available to EPA in order to increase the success of the research 

program. The SAB provides a number of specific recommendations for focusing EPA’s 

fundamental and secondary research questions associated with this topic area. 

As a starting point, the SAB recognizes that there are three primary opportunities during well 

injection for contaminants to affect drinking water resources: escape through the well, through 

the cement surrounding the well, and as a result of various steps of the hydraulic fracturing 

process itself. Assuming drilling and cementing practices for HF wells are not different from 

practices for other industry wells, the consensus of the Panel is that well drilling and cementing 

practices be researched separately from the hydraulic fracturing process itself. In doing so, the 

SAB finds the EPA can better focus on the question of the potential influence of the hydraulic 

fracturing process on drinking water resources and contamination of aquifers. 

Charge Question 4(d): Proposed Research Activities - Flowback and Produced Water

The SAB concludes that, overall, EPA has generally proposed a sound approach to address the 

research questions associated with this lifecycle stage as outlined in Table 2 (see Appendix B). 

The SAB has some recommendations for specific components of the research plan that could be 

strengthened as described further below.
9

The handling, treatment and disposal of post-fracturing produced water represents an important 

route of exposure and has potential for adverse widespread impacts. Although flowback and 

produced water are sometimes mentioned independently, these distinctions are only operational 

as there is a continuous evolution of water quality for post-fracturing produced water. To the 

extent differentiation of flowback and produced water is desired by EPA, the SAB recommends 

that EPA clearly define flowback and produced water in the main body of the Study Plan.

The SAB supports EPA’s plan to gather information on the composition of post- fracturing 

produced water from the hydraulic fracturing process as much as possible from currently 

available data, including proprietary information where possible. The SAB recommends the 

collection of water quality data before, during, and after injection, and from carefully selected 

locations, including the ongoing studies on the quality of surface waters in the regions with 

significant hydraulic fracturing activity. EPA should evaluate quality assurance/quality control 

(QA/QC) aspects of the studies that would be assessed or conducted by EPA. 

The SAB recommends that EPA consider the use of a risk assessment framework analysis (i.e., 

hazard identification, exposure assessment, dose-response assessment, and risk characterization) 

to assess and prioritize research activities for the lifecycle stages of flowback and produced 

water. Specific comments on hazard identification, exposure assessment, toxicity testing, 

analytical methods, and indicators of contamination are included within this Report’s response to 

Charge Question 2. 

Charge Question 4(e): Proposed Research Activities - Wastewater Treatment and Waste 

Disposal

The SAB concludes that, overall, EPA has generally proposed a sound approach to address the 

research questions associated with this lifecycle stage as outlined in Table 2 (see Appendix B). 

The SAB has some recommendations for specific components of the research plan that could be 

strengthened as described further below.

The Panel strongly recommends the use of scenario modeling, in concert with both retrospective 

and prospective case studies, to “define the boundaries” for activities under this portion of the 

water lifecycle. Scenario modeling involving simple mass balances should be conducted as a 

first-order effort to determine if or when dilution constitutes adequate “treatment.” Existing 

practice in some areas is to discharge return flows to wastewater treatment plants and to rely on 

dilution to “treat” a number of constituents not removed by conventional wastewater treatment 

processes, such as total dissolved solids (TDS), chloride, bromide, and non-biodegradable 

organic matter. For these constituents, simple calculations can be done to estimate effluent and 

downstream concentrations, which can then be evaluated for their potential to cause adverse 

impacts (not only to humans, via drinking water supplies, but also to other receptors in future 

studies). 

Hydraulic fracturing return flows contain many constituents that are similar to those for which 

treatment technologies exist within the state of practice of industrial wastewater treatment. For 

those constituents, SAB finds that EPA should conduct a thorough literature review to identify 

existing treatment technologies that are currently being used to treat HF wastewater, identify 
10

knowledge relevant to hydraulic fracturing return flows, and identify constituents of HF return 

waters that might merit additional attention. SAB recommends that EPA review the documented 

data in the retrospective case studies to assess the efficacy and success of industrial wastewater 

treatment operations and pre-treatment operations for hydraulic fracturing return flows. Only a 

limited number of Publicly Owned Treatment Plants (POTWs) have the ancillary treatment 

technologies needed to remove the constituents in hydraulic fracturing return waters. SAB 

recommends that EPA focus its efforts towards literature searches on POTW and industry 

management practices that can minimize the adverse effects associated with certain constituents 

such as TDS, natural organic matter (NOM), bromide, and radioactive species. In addition, EPA 

should assess the need for any special storage, handling, management, or disposal controls for 

solid residuals after treatment. EPA should assess whether land application (e.g., for disposal, 

irrigation, or road application for dust suppression or deicing) of hydraulic-fracturing associated 

wastewaters or residuals from treatment of these wastewaters, which is mentioned in the Study 

Plan, has the potential to affect drinking water resources. 

Charge Question 5: Research Outcomes

EPA has proposed to conduct certain research activities associated with all stages of the 

hydraulic fracturing water lifecycle shown in Figure 7 of the Study Plan in order to address the 

research questions posed in Table 2 of the Study Plan. Table 2 and Figure 7 are provided within 

this SAB report as Appendix B and Appendix C, respectively. EPA proposes to conduct the 

research using case studies and generalized scenario evaluations, which will rely on data 

produced by a combination of the tools listed in Section 5.3 of the Study Plan. In addition, EPA 

outlines a program of quality assurance that will be developed for all aspects of the proposed 

research. EPA’s proposed research activities for each stage of the hydraulic fracturing water 

lifecycle are outlined in Figure 9 of the Study Plan, and EPA provides brief summaries of how 

the proposed research activities will answer the fundamental research questions. Figure 9a is 

provided within this SAB report as Appendix D.

The SAB focused on the potential research outcomes that EPA identified for each step in the HF 

water lifecycle. These potential research outcomes are identified in Chapter 6 of the draft Study 

Plan, at the end of the discussion of each stage of the water lifecycle. For each potential research 

outcome listed in the draft report, the SAB determined whether the outcome is likely to be 

achieved in whole, in part, or not at all, by the proposed research. In addition to comments on 

specific outcomes for steps in the HF water lifecycle, comments on environmental justice 

research outcomes are included within this report’s response to Charge Question 2. 

EPA identified specific potential outcomes for the research related to each step in the HF water 

lifecycle. However, the SAB does not anticipate that all of these outcomes can be achieved 

given the time and cost constraints of the proposed research program. 
11

INTRODUCTION

Background

In January 2010, EPA’s Office of Research and Development (ORD) initiated planning for a 

study to assess the potential impacts of hydraulic fracturing on drinking water resources. EPA 

proposed a study scope in March 2010 that was reviewed by the Science Advisory Board (SAB) 

in an open meeting on April 7-8, 2010; SAB’s Report on its review of the study scope was 

provided to the Administrator in June 2010. In its response to EPA in June 2010, the SAB 

endorsed a lifecycle approach for the study plan, and recommended that: (1) initial research be 

focused on potential impacts to drinking water resources, with later research investigating more 

general impacts on water resources; (2) five to ten in-depth case studies be conducted at 

“locations selected to represent the full range of regional variability of hydraulic fracturing 

across the nation”; and (3) engagement with stakeholders occur throughout the research process.

Subsequently, EPA developed a draft Hydraulic Fracturing Study Plan and requested SAB 

review of the draft Plan. The draft Study Plan assesses the potential impacts of hydraulic 

fracturing on drinking water resources, and identifies the driving factors that affect the severity 

and frequency of any potential impacts. The draft Study Plan proposes to assess potential 

impacts from five aspects of the water lifecycle associated with hydraulic fracturing: Water 

Acquisition, Chemical Mixing, Well Injection, Flowback and Produced Water, and Water 

Treatment and Waste Disposal. As noted in the draft Study Plan, EPA plans to conduct this 

lifecycle analysis through literature reviews, data gathering and analysis, modeling, laboratory 

investigations, and field investigations and case studies.

The SAB was asked to comment on various aspects of EPA’s approach for the Study Plan, 

including EPA’s proposed water lifecycle framework for the study plan, EPA’s proposed 

research questions that would address whether or not hydraulic fracturing impacts drinking water 

resources, and EPA’s proposed research approach, activities, and outcomes. EPA identified the 

proposed research questions from stakeholder meetings and a review of the existing literature on 

hydraulic fracturing. Stakeholders also helped EPA to identify the potential case study sites 

discussed in the draft study plan. 

The Panel reviewed the draft Study Plan and background materials provided by EPA, and 

considered public comments that were received on the draft Study Plan, held public meetings on 

March 7-8, 2011 to provide advice to EPA on its draft Study Plan. The Panel held follow-up 

public teleconference calls on May 19 and May 25, 2011, to discuss the external draft SAB 

Report dated April 28, 2011. The Panel considered oral statements that were received on the 

draft Study Plan during the public meetings and teleconferences. 

The updated external draft SAB Report dated June 14, 2011, was submitted to the chartered SAB 

for discussion at the July 5, 2011, public teleconference. The external draft SAB Report was 

revised based on comments received from the Board. 
12

The enclosed report provides the advice and recommendations of the SAB through the efforts of 

the SAB Hydraulic Fracturing Review Panel. EPA will consider the comments from the SAB 

during the development of its final plan to study the potential impacts of hydraulic fracturing on 

drinking water resources. 

Charge Questions to the Panel

The Agency’s Charge to the Panel (Appendix A) included a total of five questions, which were 

broken into nine total charge questions that were reviewed by the Panel:

Charge Question 1: Water Use in Hydraulic Fracturing

EPA has used the water lifecycle shown in Figure 7 to characterize hydraulic fracturing 

and to identify the potential drinking water issues. Please comment on the 

appropriateness of this framework for the study plan. Within the context of the water 

lifecycle, does the study plan adequately identify and address the areas of concern?

Charge Question 2: Research Questions

EPA has identified both fundamental and secondary research questions in Table 2. Has 

EPA identified the correct research questions to address whether or not hydraulic 

fracturing impacts drinking water resources, and if so, what those potential impacts may 

be?

Charge Question 3: Research Approach

The approach for the proposed research is briefly described in Chapter 5. Please provide 

any recommendations for conducting the research outlined in this study plan, particularly 

with respect to the case studies. Have the necessary tools (i.e., existing data analysis, 

field monitoring, laboratory experiments, and modeling) been identified? Please 

comment on any additional key literature that should be included to ensure a 

comprehensive understanding of the trends in the hydraulic fracturing process.

Charge Question 4(a): Proposed Research Activities - Water Acquisition

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for the Water Acquisition stage of the water 

lifecycle? Please provide any suggestions for additional research activities.

Charge Question 4(b): Proposed Research Activities - Chemical Mixing

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for the Chemical Mixing stage of the water 

lifecycle? Please provide any suggestions for additional research activities.
13

Charge Question 4(c): Proposed Research Activities - Well Injection

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for the Well Injection stage of the water lifecycle? 

Please provide any suggestions for additional research activities.

Charge Question 4(d): Proposed Research Activities - Flowback and Produced Water

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for the Flowback and Produced Water stage of the 

water lifecycle? Please provide any suggestions for additional research activities.

Charge Question 4(e): Proposed Research Activities - Wastewater Treatment and Waste Disposal

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for the Wastewater Treatment and Waste Disposal

stage of the water lifecycle? Please provide any suggestions for additional research 

activities.

Charge Question 5: Research Outcomes

If EPA conducts the proposed research, will we be able to:

a. Identify the key impacts, if any, of hydraulic fracturing on drinking water 

resources; and 

b. Provide relevant information on the toxicity and possible exposure pathways of 

chemicals associated with hydraulic fracturing?
14

RESPONSE TO THE CHARGE QUESTIONS

Water Use in Hydraulic Fracturing

Charge Question 1: EPA has used the water lifecycle shown in Figure 7 to characterize 

hydraulic fracturing and to identify the potential drinking water issues. Please comment 

on the appropriateness of this framework for the study plan. Within the context of the 

water lifecycle, does the study plan adequately identify and address the areas of concern?

3.1.1. General Comments

EPA has developed a Study Plan that identifies a set of proposed research activities associated 

with each stage of the hydraulic fracturing water lifecycle, from water acquisition through the 

mixing of chemicals and actual fracturing to post-fracturing production, including the 

management of flowback and produced water and ultimate treatment and disposal. 

In general, the SAB concludes that EPA’s use of the water lifecycle depicted in Figure 7 (see 

Appendix C) of the draft study plan is an appropriate framework to characterize hydraulic 

fracturing and to identify the potential drinking water issues, and adequately identifies and 

addresses the areas of concern identified for each stage of the hydraulic fracturing water 

lifecycle. However, the SAB finds that the diagram is incomplete, and has several 

recommendations to strengthen the framework and provide an improved assessment of potential 

drinking water issues. 

The SAB recommends that EPA make certain adjustments to the hydraulic fracturing lifecycle 

framework. EPA should assess water quantity impacts on the local watershed mass balance, and 

the framework depicted in Figure 7 should link water fluxes associated with hydraulic fracturing 

to water flows in the surrounding natural hydrological cycle. The water mass balance 

assessment is a critical effort, and EPA should initially focus the water mass balance assessment 

towards the case study efforts. 

EPA should also add a postclosure/well abandonment phase as a new component to Figure 7, and 

SAB recommends that EPA separately consider this phase in the Study Plan. SAB recognizes 

that potential risks for this new component may not be at the same level as potential risks in 

other phases of the lifecycle. EPA should determine if there is historical evidence to indicate if 

there are any differences regarding the postclosure/well abandonment phase of hydraulic 

fracturing wells when compared to the postclosure/well abandonment phase for other types of 

wells. 

EPA should also assess interbasin transfers of post-fracturing produced water in order to identify 

possible water quality and quantity issues associated with such transfers. In addition, EPA 

should assess additional sources of water quality impacts beyond those indicated in Figure 9a 

(see Appendix D). 
15

3.1.2. Specific Comments

The SAB recommends that EPA make certain adjustments to the hydraulic fracturing lifecycle 

framework. First, EPA’s framework depicted in Figure 7 should involve imbedding water fluxes 

associated with hydraulic fracturing within water flows in the surrounding natural hydrological 

cycle. To take this broader view, EPA should reformat Figure 7 to put a box around the block 

diagram that links to the hydrological cycle. Also, within the first block of the framework (i.e., 

the water acquisition block), EPA should change the wording from ‘Water availability’ to ‘Water 

availability and environmental flows,’ and also change the wording from ‘Impact of water 

withdrawal on water quality’ to ‘Impact on environmental fluxes and water quality.’ 

The SAB agrees that assessing the water mass balance for any particular site or collection of sites 

is an important undertaking and supports EPA’s efforts to conduct this analysis. The SAB 

concludes that EPA should initially focus this water mass balance assessment towards the case 

study efforts. A critical issue associated with water mass balance is assessing and accounting for 

the change in hydrologic/environmental flows. When assessing the water balance 

interconnection between natural flow and flow associated with hydraulic fracturing activities, a 

large water volume is removed and stored for hydraulic fracturing activities, and EPA should tie 

that water into the broad hydrological cycle on a regional scale.

In addition, SAB recommends that EPA include feedback loops that assess interbasin transfers of 

flowback and produced water, in order to identify possible water quality and quantity issues 

associated with such transfers. 

Regarding water quality impacts, SAB concludes that some other sources of impacts beyond 

those indicated in the Figure 9a (see Appendix D) should be assessed. It is important to 

recognize that substantial credibility in the impact analysis for individual chemicals will result 

when complete mass balances (i.e., summations of transfers to air, water, soil, and other media) 

are assessed. EPA should also consider spatial (e.g., geographic locations of wells and their 

proximity to nearby drinking water resources) and temporal (e.g., length of time associated with 

operation of hydraulic fracturing wells within a watershed) issues relevant to assessing 

cumulative water quality impacts. The SAB recognizes that there are difficulties in 

incorporating spatial and temporal issues into the water quality impact assessment, but EPA 

should attempt to provide some boundaries for these issues to assist in determining what future 

work may be useful. 
16

Research Questions

Charge Question 2: EPA has identified both fundamental and secondary research questions 

in Table 2. Has EPA identified the correct research questions to address whether or not 

hydraulic fracturing impacts drinking water resources, and if so, what those potential 

impacts may be?

3.2.1. General Comments

EPA has identified a comprehensive set of research questions to address the primary mechanisms 

and pathways that can allow hydraulic fracturing to impact drinking water resources. The 

questions cover each step of the life cycle of a hydraulic fracturing process that can impact 

drinking water and are appropriately focused on the unique aspects of hydraulic fracturing that 

can lead to such impacts. EPA has identified research questions to address whether or not 

hydraulic fracturing impacts drinking water resources. 

As presented by EPA staff at the March 7, 2011 SAB meeting, EPA’s budget for the research on 

HF impacts to drinking water resources is as follows:

Fiscal Year 2010 (Enacted): $1.9 million.

Fiscal Year 2011 (President’s Request): $4.4 million.

Fiscal Year 2012 (President’s Request): $6.1 million.

EPA’s schedule for delivery of research products includes completion of a report of interim 

research results in 2012. This interim report will contain a synthesis of EPA’s research to date 

and will include results from retrospective case studies and initial results from scenario 

evaluations. Since certain portions of the work described in the draft Study Plan, including 

prospective case studies and work performed under EPA’s Science to Achieve Results (STAR) 

program, are longer-term activities that are not likely to be finished by 2012, additional reports 

of study findings will be published as these long-term activities progress, with a follow-up report 

on the study in 2014.

EPA’s use of retrospective case studies will focus on investigating reported instances of drinking 

water resource contamination or other impacts in areas where hydraulic fracturing has already 

occurred. EPA will conduct retrospective case studies at three to five sites across the United 

States; these studies will use existing data and possibly field sampling, modeling, and/or parallel 

laboratory investigations to determine the potential relationship between reported impacts and 

hydraulic fracturing activities. EPA will also conduct prospective case studies that will involve 

sites where hydraulic fracturing will occur after the research is initiated. These case studies 

allow sampling and characterization of the site before, during, and after water extraction, 

drilling, hydraulic fracturing fluid injection, flowback, and gas production. EPA will work with 

industry and other stakeholders to conduct two to three prospective case studies in different 

regions of the United States. 

The SAB finds that the Study Plan provides inadequate detail on how to address the overall 

research questions presented in Table 2 (see Appendix B) and discussed within the draft Study 

Plan, and that EPA should develop more specific research questions that could be answered 
17

within the budget and time constraints of the project. EPA should conduct a well-focused study 

so that critical research questions are identified, approaches are designed that will enable 

answering those questions, and conclusions reached are supported by appropriate analysis. At 

the same time, EPA’s framework should take a broader view with regard to water quantity than 

depicted in Figure 7 (see Appendix C), and link water fluxes associated with hydraulic fracturing 

to water flows in the surrounding natural hydrological cycle. The SAB provides 

recommendations for supplementing and revising the existing questions. These 

recommendations are designed to recognize explicitly key issues that may not be adequately 

addressed in the current questions. 

SAB provides comments that may affect the primary and secondary research questions and how 

they are answered at each life cycle stage. To the extent that the Study Plan is being designed to 

inform decision-making related to an EPA regulatory framework, the Study Plan should include 

specific research questions aimed at this objective. An important challenge facing the study is 

the diverse nature of hydraulic fracturing operations around the country. The geological setting, 

the hydrological setting, the community setting and the requirements and standard operating 

procedures at each stage of the hydraulic fracturing life cycle vary across the country. These 

differences can give rise to fundamental differences in the nature of the potential impacts to 

drinking water resources. For example, the limited availability of reinjection wells in the 

Marcellus Shale region gives rise to a completely different set of potential impacts to drinking 

water than in areas where reinjection of produced waters is routine. 

EPA proposes to conduct scenario evaluations that will assess the environmental futures and 

impacts of hydraulic fracturing operations at various spatial and temporal scales in the selected 

case study areas. The scenarios will include at least two futures: (1) average annual conditions in 

10 years based on the full exploitation of non-conventional natural gas and (2) average annual 

conditions in 10 years based on sustainable water use in hydraulic fracturing operations. The 

SAB finds that the scenario evaluation does not, but should, cross all research questions. See 

further discussion on this topic under this Report’s response to Charge Question 3. The specific 

objectives of case studies are unclear and should be clarified. As the study moves forward, it is 

important for EPA to explain the rationale for the selected case studies.

SAB recommends that EPA clarify whether the research focus is on hydraulic fracturing in shale 

gas production, conventional natural gas production, coal bed methane production, or other types 

of hydraulic fracturing activity. SAB is not suggesting that studies be limited to particular type 

of activity; rather, EPA should be careful with the realm of inference drawn in the report to 

different activities (i.e., results should not be generalized across all types of HF activity). 

The Study Plan should address the cumulative consequences of carrying out multiple HF 

operations in a single watershed or region. While the Study Plan includes proposed research 

activities in the context of water acquisition, considering the cumulative impacts of large water 

withdrawals, the panel notes that there are many other aspects to understanding cumulative 

effects of the hydraulic fracturing process. For example, considering the role of disturbing and 

revegetating many acres of land, the presence of multiple well pads on the landscape, and how 

these changes to the landscape in turn affect the water budget and downstream water quality. 

While detailed research on cumulative impacts may be beyond the scope of the current study, the 
18

incremental impacts of hydraulic fracturing operations should be well characterized in the 

current study and a framework for assessment of cumulative impacts should be established. This 

will provide the foundation for subsequent assessment of total environmental exposures and 

risks, and cumulative impacts. 

SAB recommends that EPA conduct research in a few additional areas. EPA should assess the 

capacity of microseismic data to provide detailed information about extent of fracturing and to 

assist in the hydraulic fracturing modeling (see discussion under Charge Question 4c). In 

addition, potential impacts to drinking water may be the result of the hydraulic fracturing process 

or the result of the manner in

which it is implemented (e.g., the particular manner in which site preparation and drilling are 

conducted). In retrospective case studies there is concern that it may not be possible to obtain 

sufficient data to separate risks that may be associated with the various management practices 

employed.

The SAB recommends EPA include both prospective and retrospective case studies as planned 

because the studies address different questions and perspectives. In retrospective case studies 

there is concern that it may not be possible to obtain sufficient data to separate risks that may be 

associated with the various management practices employed. 

In prospective case studies there is concern that the best management practices examined in these 

case studies will not necessarily be used at other sites, and that the water quality parameters that 

are analyzed before, during, and after injection of the HF fluids will probably undergo minimal 

change during the relatively short duration of the research program. Also, the number of 

retrospective and prospective case studies that can be evaluated in the given time will be limited, 

which will make it difficult to generalize from the data gathered. The SAB recommends that 

EPA take a long view, and consider what kind of data will be desired in ten years in order to 

design the data collection protocols for the prospective studies. Further, the SAB notes that the 

selected case study locations must be chosen based on reasonable, mechanistically possible 

contamination scenarios, incorporating uncertainty.

An additional issue is that EPA needs to view the environmental concerns and issues in the 

context of the local community outcomes should be identified by EPA for environmental justice 

issues. As noted in Section 9 of the Study Plan, to address these concerns, EPA plans to 

combine the data collected on the locations of well sites within the United States with 

demographic information, such as race, color, national origin, and income, to screen whether 

hydraulic fracturing disproportionately impacts some citizens and to identify areas for further 

study. The SAB concludes this would effectively inform environmental justice discussions. The 

SAB recommends that EPA develop one or more specific research outcomes related to the 

planned research pertaining to environmental justice issues. For the case studies, EPA should 

also assess demographic information, such as race, color, national origin, and income, to screen 

whether hydraulic fracturing disproportionately impacts some citizens near sites used for the case 

studies (e.g., identify whether more HF wells are near communities with lower incomes). Also, 

EPA should conduct systematic interviews with local public health officers to identify potentially 

vulnerable subpopulations, the consideration of fairness in local decision-making, and the 

impacts of current operations associated with HF operations at case study locations.
19

Another issue is the importance of assessing uncertainty at each step in the research study. 

Given time and resource constraints, the studies will not be able to answer all questions with a 

high degree of certainty. The SAB recommends that EPA explicitly identify or estimate the 

uncertainty or confidence in all research conclusions, and in the assessment of cause and effect 

associated with potential HF impacts to drinking water supplies. The quality of the information 

on which the research was based as well as any uncertainties arising in the conduct of the 

research should be evaluated, at least in a preliminary manner. This is particularly true for case 

studies and evaluations of current practices in that it is expected that these portions of the 

research will be based upon grey literature sources that have not been peer reviewed or subject to 

the same quality constraints that will govern the proposed studies. The need to collect 

proprietary information may limit the quality of the research product. 

The SAB has a number of specific concerns noted below associated with the research questions 

at individual lifecycle stages. Additional specific comments on each of the lifecycle stages are 

included within this report’s responses to Charge Questions 4(a) through 4(e).

3.2.2. Specific Comments

Water acquisition

The potential impacts associated with water acquisition are clearly related to the volume of water 

required and the availability and quality of such water to the community impacted. EPA should 

assess the volume of water in context with the needs and availability of water to the surrounding 

community, and a series of secondary questions should be added to reflect this. For example: 

What are the depths of functional groundwater wells in the area of hydraulic fracturing and what 

is the potential relationship between these wells and hydraulic fracturing activities both on the 

surface and below ground? 

The Study Plan proposes a sustainability analysis that will reflect minimum river flow 

requirements and aquifer drawdown for drought, average, and wet precipitation years. Minimum 

river flow requirements need to be determined as suggested, but also, more importantly, “What 

are the environmental flow requirements?” Minimum flows and environmental flows are quite 

different concepts. Environmental flow refers to the amount of water needed in a watercourse to 

maintain healthy ecosystems. Minimum flow is a level below which the amount of flow in a 

specified watercourse should not drop at a given time. This term is also used in law to denote 

water which is expressly dedicated to remain in the stream channel which should not be diverted 

for other purposes. These flow requirements should be determined based on hydrological 

processes in the region where hydraulic fracturing is being practiced.

The Study Plan also emphasizes the relationship between water acquisition (related to 

availability) and water quality. Additional questions should relate this relationship to different 

sources of water. For example: How different will impacts of water withdrawal be on different 

water sources, e.g., different stream types (perennial and intermittent) and lakes, and their water 

quality based on their different base geology? 
20

The draft Study Plan should recognize the differences between acquiring low quality water that 

is not considered a valuable resource to the community as opposed to displacing agricultural or 

drinking water that could be used by the community. This is an area where the cumulative 

impacts of well field development as opposed to single well impacts will be important. For 

example, a secondary question addressing this might be: What are the cumulative effects of 

water acquisition for multiple well sites relative to the effects of one or limited well sites? 

Chemical mixing

The fundamental question in this area is focused on accidental releases during the mixing 

process. The secondary questions appropriately emphasize the importance of the composition 

and potential toxicity of the fracturing fluids. Similarly, the total volumes and the physical and 

chemical properties of the constituents must be identified to address potential impacts at 

subsequent life cycle stages. The total quantities and physical and chemical properties can also 

be useful in subsequent evaluations of other issues not within the scope of the present study, for 

example, air emissions from the chemical mixing operations. The SAB recommends that the 

secondary question be expanded to explicitly recognize the need for information regarding 

volumes and physical and chemical properties of the mixing components. 

The potential toxicity of the fracturing fluids will likely be addressed primarily through literature 

sources. The SAB strongly discourages using any of EPA’s limited resources for toxicity studies 

of chemical constituents. SAB recommends that EPA explicitly recognize this in the framing of 

the secondary questions. 

EPA should assess the likelihood of releases during chemical mixing and the relationship of the 

frequency and volume of releases to best management practices to the extent possible. SAB 

recommends that EPA add an explicit secondary question to address this need. For example: 

Have different practices for chemical mixing resulted in different frequencies of spills and 

different volumes of spills when they occur? 

Well injection

This stage of the life cycle of hydraulic fracturing should be explicitly separated into well 

construction and well completion. Drilling and cementing are construction activities whereas 

fracturing is considered a completion activity. Well construction may lead to impacts on 

drinking water resources and any weaknesses or failures in construction will lead to subsequent 

problems during completion activities and/or operations. Well construction could be considered 

another life-cycle stage for hydraulic fracturing so that the potential impacts to drinking water 

resources could be addressed by specific research questions. Since subsequent well-bore failure 

is likely associated with problems during construction, a secondary question focused on the 

ability to detect and correct well-bore construction problems prior to or during injection may be 

appropriate. A secondary question on the influence of management practices, such as cementing 

casings all the way to the surface, should also be included. For example: What have been the 

management practices relative to cementing casings and what has been the history of failure of 

different practices? Re-fracturing a formation may put additional stresses on a well, particularly 
21

if re-fracturing is conducted years after initial construction. It may not be possible to address this 

in the proposed study, but any existing evidence of this practice as a possible mechanism for 

drinking water impacts should be reviewed. 

The remaining secondary questions are appropriate for the well injection and operation portion 

of the life cycle. The secondary questions should explicitly recognize, however, that the fate and 

transport of substances of concern includes not only substances introduced by the fracturing 

fluids but other substances that might be mobilized or rendered more toxic by the introduction of 

the fracturing fluid. For example, will changes in redox conditions in the subsurface due to 

fracturing fluid injection lead to redox changes and mobilization of metals such as arsenic, 

selenium and chromium or encourage/discourage specific metabolic processes?

The volume and depth of injection relative to subsurface drinking water resources is an important 

factor in the potential impact of the injection of fracturing fluids. As indicated previously, 

placing these quantities in context (cumulative impacts of adjacent wells, differences in geology 

and water availability, quality and location) is difficult given time and resource constraints, but 

the study should attempt to do so to the extent possible. A specific factor in some areas that may 

influence injection behavior is the presence of unplugged abandoned wells. A secondary 

question is recommended that explicitly recognizes the need to place results in the context of the 

local geology and history. For example: What is the relationship between well injection depths 

and impacts of injection fluids, considering local geology and historic use as evidenced, for 

example, by unplugged wells?

Since hydraulic fracturing occurs in the deep subsurface environment where it is difficult to 

assess effects on ground water resources, the operation and injection life cycle of a hydraulically 

fractured well has significant uncertainties. This lifecycle analysis is a critical component of the 

proposed study. 

Flowback and produced water

The SAB concludes that the draft Study Plan’s secondary questions in this lifecycle stage 

correctly emphasize the importance of the composition of post-fracturing produced water and its 

variability. How the composition of the flowback and produced water may vary as a function of 

management practices and local geology is important but difficult to assess given time and 

resource constraints. EPA should address this question to the extent possible, including an 

assessment of the uncertainty in the conclusions. A secondary question explicitly identifying this 

as an area of concern may be appropriate. For example: What factors such as management and 

local geology can be identified as primary drivers of composition of flowback and produced 

water, and what is the uncertainty of this determination?

The SAB concludes that given the constraints of time and funding, EPA should attempt to 

identify the fate of fracturing fluid components that are deemed to be of highest priority that are 

introduced with the injection. A specific secondary question that asks “What fraction of the 

injected components are returned to the surface and what is the likely fate of any components not 

returned to the surface?” may be appropriate. 
22

As with chemical mixing, EPA should identify the cause and likelihood of spills or releases of 

flowback or produced water, as well as management practices that reduce their likelihood or 

mitigate their impact. It may be appropriate for EPA to expand the existing secondary questions 

to explicitly identify the need for identifying the likelihood of spills or releases and the 

effectiveness of mitigation practices. 

Wastewater treatment and disposal

The form and potential impacts of wastewater treatment and disposal vary significantly with 

local conditions and practices. The lack of available reinjection wells in the Marcellus Shale 

area creates substantially greater concern for wastewater treatment practices in this area. EPA 

should explicitly identify these variations across the country and include a secondary question 

that recognizes the need to assess these variations. For example: How does the potential for 

reinjection vary across the country and across geological formations where hydraulic fracturing 

is practiced?

Specific issues associated with wastewater treatment are not currently identified in the secondary 

questions. Inorganic species such as bromide and radionuclides, as well as bulk parameters such 

as salinity, for which conventional wastewater treatment is largely ineffective, are of major 

concern. The presence of these constituents has also led to concerns about potential ecological 

effects and effects on drinking water treatment downstream (e.g., formation of brominated 

disinfection by-products). The SAB recommends that EPA add a secondary question focusing 

on these contaminants of concern. For example: What is the potential for species for which 

conventional wastewater treatment is largely ineffective (e.g., salinity, bromide, radioactive 

inorganics) to enter drinking water resources downstream from industrial wastewater treatment 

facilities?

Postclosure/well abandonment 

The SAB recommends that EPA add a postclosure/well abandonment phase as a new component 

to Figure 7, and separately consider this phase in the Study Plan. SAB recognizes that potential 

risks for this new component may not be at the same level as potential risks in other phases of 

the lifecycle. EPA should determine if there is historical evidence to indicate if there are any 

differences regarding the postclosure/well abandonment phase of hydraulic fracturing wells 

when compared to the postclosure/well abandonment phase for other types of wells. 

In addition, SAB recommends that EPA consider adding the following drinking water issues, 

primary research questions, and secondary research questions to the second stage in Table 2 (see 

Appendix B) of the draft Study Plan relative to the suggested “post closure and well 

abandonment” life cycle stage:

Drinking Water Issues:

• Long-term water quality impacts to water quality of primary aquifers and secondary 

aquifer water resources.
23

Primary Questions:

• What is the long-term mechanical integrity of wells that have been hydraulically 

fractured? 

• What monitoring schedule and types of monitoring are needed to better understand longterm integrity?

Secondary Questions:

• What field techniques are needed to assess long-term integrity of hydraulically fractured 

wells to ensure long-term mechanical integrity, particularly for casing and cementing?

• What modeling techniques are needed to predict integrity over long time horizons relative 

to material fatigue, seismic activity, and rock mechanics?

The SAB recommends that EPA consider the use of a risk assessment framework analysis (i.e., 

hazard identification, exposure assessment, dose-response assessment, and risk characterization) 

to assess and prioritize research activities for the lifecycle stages associated with hydraulic 

fracturing. 

The SAB concludes it will be difficult for EPA to identify comprehensively the toxicity of 

chemical additives, apply tools to prioritize data gaps, and identify chemicals for further 

assessment. The SAB does not agree that it will be possible for EPA to collect and evaluate new 

data on human toxicity of HF chemical additives given the cost and time constraints of the 

current project. Therefore, SAB strongly recommends that none of the proposed toxicity testing 

of chemical constituents be conducted at this time. 

At this time, EPA should focus on hazard identification and potential human exposure for the 

components of HF fluids in the current research effort. The SAB anticipates that an important 

opportunity for human health exposure is likely to be through exposure to liquids that are 

brought back to the surface during hydraulic fracturing operations, such as during surface water 

management of post-fracturing produced waters and during disposal of treated wastewater. In 

addition, since groundwater can potentially be contaminated by HF in a number of ways 

(including leakage from liquid storage areas; leakage from the injection wells; leakoff during 

hydraulic fracturing potentially along faults or up abandoned wells; seepage into the ground if 

hydraulic-fracturing associated wastewaters or residuals from treatment of these wastewaters are 

land applied; facilitated transport for natural gas; and other means), potential groundwater 

contamination is another important opportunity for human health exposure. EPA will be 

obtaining information as the study progresses and should use its expertise to set priorities for 

these and other pathways as needed. EPA should evaluate the toxicity of selected constituents 

determined to have a high potential for exposure for which toxicity is unknown through literature 

sources and available databases. The SAB recommends that EPA explicitly recognize this in the 

framing of the secondary questions. 

EPA should collect and review pre-existing data on toxicity of HF additives, and conduct a 

limited effort to estimate toxicity (such as through toxicity estimates using quantitative structureactivity relationships, or QSARs, for HF additives for which no pre-existing toxicity data exist 
24

and a high potential for exposure is likely). The review of existing data and of the QSARs 

should be used to identify chemicals for further assessment.

The SAB finds the development of potential chemical indicators of contamination associated 

with hydraulic fracturing an appealing approach. However, SAB concludes that it may be 

difficult to achieve a practical indicator approach or identify a set of such contamination 

indicators within the time allotted for the study. The EPA can likely develop a list of possible 

indicators for which analytical methods exist that can be tested in the prospective case studies 

and scenario modeling. Tracers that can be added might be another tactic to consider but must 

take into consideration public and industry concerns about such an approach. SAB finds that 

EPA’s consideration of inorganic salts and organic HF additives (for which analytical methods 

already exist) as contamination indicators can adequately support the research outcome related to 

toxicity assessment. 

The SAB also recommends that development of analytical methods for specific constituents that 

do not have existing EPA-approved methods should be given a low priority due to cost and time 

constraints. The EPA should focus on existing methods for the near term effort and develop a 

list of priorities for future efforts based on the first-order hazard assessment.

Two other potential products of this research activity are to prioritize a list of chemicals 

requiring further toxicity study and to develop Provisional Peer-Reviewed Toxicity Values 

(PPRTVs) for chemicals of concern. The SAB also recommends that these activities have a low 

priority if exposure to a substance is not likely and/or levels of exposure are minimal (e.g., parts 

per trillion). For prioritizing chemicals for further study, EPA should review the process it used 

to develop its most recent Contaminant Candidate List (CCL) and apply any lessons learned. 

Toxicity testing of hydraulic fracturing fluids could perhaps be separately conducted as a long 

term research study, potentially through EPA’s Science to Achieve Results (STAR) program, or 

through a CRADA (Cooperative Research and Development Agreement) with industry. EPA 

could develop a prioritized list of components requiring future studies relating to toxicity and 

human health effects. Scenario modeling may be useful in developing the list of priorities for 

future toxicity testing. 
25

Research Approach

Charge Question 3: The approach for the proposed research is briefly described in 

Chapter 5. Please provide any recommendations for conducting the research outlined in 

this study plan, particularly with respect to the case studies. Have the necessary tools 

(i.e., existing data analysis, field monitoring, laboratory experiments, and modeling) been 

identified? Please comment on any additional key literature that should be included to 

ensure a comprehensive understanding of the trends in the hydraulic fracturing process.

3.3.1. General Comments

EPA’s research approach involves application of a broad range of scientific expertise in 

environmental and petroleum engineering, ground water hydrology, fate and transport modeling, 

and toxicology, as well as many other areas, and use of case studies and generalized scenario 

evaluations, to address the key questions associated with each of the five water cycle stages of 

hydraulic fracturing. 

The SAB concludes that EPA has identified the necessary tools in its overall research approach 

as outlined in the Study Plan to adequately assess potential impacts of hydraulic fracturing on 

drinking water resources. However, the SAB provides several recommendations for improving 

the tools that have been identified and also offers recommendations for additional focused 

analyses. The SAB concludes that the Study Plan provides limited detail on anticipated data 

analysis, management, and storage (including model simulation results), and recommends that 

the Study Plan include such details. The SAB recommends that EPA consider using existing 

data analysis methods rather than developing new methods due to time and budget constraints. 

EPA should also carefully consider the quality of various types of data that would be used within 

the analysis (industry data, local and non-industry data). It is imperative for EPA to set a 

standard for use of data and prior research information that will support the present research 

effort. The SAB notes that while anecdotal information and publications that have not been peer 

reviewed may provide useful data, EPA should classify the data as such. Since the scientific 

value of grey literature can be uncertain, EPA should appropriately qualify any use of such 

literature within the draft report. As much as possible, peer reviewed information should be 

employed and complete citations should be provided for that information. The SAB also 

recommends that EPA consider archiving samples for later use.

The SAB finds that the Study Plan generally overemphasizes case studies in the study approach, 

and underemphasizes the review and analysis of existing data and the use of scenario analysis. 

However, the SAB recognizes that case studies will likely provide accurate information on 

hydraulic fracturing fluids and well operations, although difficulties associated with collecting 

proprietary information may limit the quality of the research product. The SAB agrees there is 

significant value to the synthesis of existing data, and that EPA should review all available data 

sources to learn from what is already known about the relationship of hydraulic fracturing and 

drinking water resources. The SAB also provides citations for additional literature that EPA 

should assess to ensure a comprehensive understanding of the trends in the hydraulic fracturing 

process and the potential impacts of hydraulic fracturing on drinking water resources.
26

3.3.2. Specific Comments

In addition to the general comments provided above, the SAB specifically considered issues of 

research approach including: partnering, the value of the case studies, the role of scenario 

evaluation, the analysis of existing data, and the methods described for the research. The SAB’s 

recommendations for each of these topics are provided below.

Partnering

Table A2 lists a significant EPA role in the research and some collaborators within the federal 

agencies (U.S. Department of Energy National Energy Technology Laboratory, NETL, and U.S. 

Geological Survey, USGS). Table F1 includes extensive collaborators for the case study work. 

However, it is not clear what data may be available from collaborators involved in the analysis of 

existing data, as well as the extent of the existing data, the laboratory studies or the scenario 

development and analysis. While EPA has extensive expertise and the timeline is short on this 

study, the SAB recommends EPA consider expanding the research team to include researchers 

with experience in this area of investigation (especially those with experience in well 

construction and fracturing operations). 

Case Studies

The SAB generally agrees that the case study approach would be a useful endeavor, since case 

studies could potentially provide high quality data from specific hydraulic fracturing sites related 

to the core research questions to be answered. However, the draft Study Plan does not provide 

adequate justification for the purpose of the case studies, link the expected results to the specific 

research questions, or explain how models will be integrated among the different research 

components. Thus, there was insufficient information to evaluate the likelihood of success from 

this research approach. The SAB recommends that Table 1 be revised to include an additional 

column indicating how case studies link to research questions. 

There is concern that the number of case studies planned might be insufficient to span the range 

of geological and hydrological regimes where drilling is active or anticipated. There is concern 

that the case studies will ultimately be too limited in scope for results to be applied generally. 

Thus, the Panel discussed the total number of case studies needed to yield useful data for the 

research program, and whether a statistically acceptable number of case studies could be 

undertaken to meet the research objectives. The SAB did not reach consensus on this point 

because the specific objectives of these case studies are unclear. As the study moves forward, it 

is important for EPA to explain the rationale for the selected case studies.

 

The retrospective case studies described include three to five sites where possible drinking water 

contamination was observed related to hydraulic fracturing. All the sites described are in small 

geographic areas and represent potential groundwater contamination. No case study deals with 

the potential effects of large scale, basin-wide disposal practices on drinking water resources. 

The SAB recommends that EPA conduct at least one case study with this larger watershed-scale 

focus. The SAB specifically recommends that EPA consider conducting a case study in the Ohio 

River Basin of Southwestern Pennsylvania, since this is a location where such watershed-scale 

drinking water impacts are suspected. 
27

The prospective case studies appear to be at small geographic scale and, similar to the 

retrospective case studies and, do not incorporate a watershed level approach. The SAB 

expresses concern that the prospective case studies do not have clearly defined boundaries. For 

example, it is unclear if waste disposal will be incorporated in the case studies. The SAB 

recommends a full life cycle approach, as EPA has proposed for this project, be applied to the 

prospective case studies, where life cycle includes the acquisition of water through to disposal of 

wastewater across multiple potential options. The case study plan describes monitoring, but 

insufficient detail is provided to assess the suitability of the target chemicals. The SAB 

recommends that the case study monitoring plan target specific measurements and not be 

developed as a general plan. 

The SAB discussed the relative merit of prospective versus retrospective case studies, especially 

given the budget constraints. After extensive discussion of the importance of the different 

components of each type of case study, the Panel concluded that there is value in each. While 

the difficulties of completing both case study formats within the limits of time and budget was 

discussed, the SAB recommends EPA include both prospective and retrospective case studies as 

planned because the studies address different questions and perspectives. The SAB notes that 

retrospective studies conducted at sites with known environmental and health issues would 

provide information on sources, fate and transport of releases of hydraulic fracturing 

contaminants to the environment. The prospective studies will help identify limitations of 

existing studies and data, what data are needed for future studies, and situations where hydraulic 

fracturing would be less likely to present significant environmental or health problems. The 

prospective studies would also provide useful information on water mass balance, well drilling 

operations, treatment system performance, health and safety issues of chemical mixing, and other 

issues. The SAB notes that while prospective studies may not provide useful information on 

long term hydraulic fracturing performance in deep formations, such studies may be helpful and 

representative for assessing impacts from hydraulic fracturing operations that occur at the surface 

because techniques for assessing surface environments are much better developed. The SAB 

recommends that EPA take a long view, and consider what kind of data will be desired in ten 

years in order to design the data collection protocols for the prospective studies. Further, the 

SAB notes that the selected case study locations must be chosen based on reasonable, 

mechanistically possible contamination scenarios, incorporating uncertainty.

Scenario Evaluation 

The SAB notes that the scenario evaluation component of the research plan was not as clearly 

articulated as the case studies. For example, it is unclear how “typical management and 

engineering practices in representative geological settings” will be selected for scenario 

generation or how system vulnerability will be incorporated into models. The Panel discussed 

using scenario evaluations to examine “worst case scenarios” and establish boundaries for 

subsequent research tasks. For example, if the worst case scenario in a given situation would 

lead to nondetectable levels of contamination, then monitoring for contaminants in that setting 

would waste precious resources. If scenario modeling shows that ground water contamination 

would occur only after a long period of time, then that scenario would use additional scenario 

modeling rather than monitoring wells to assess potential groundwater contamination. If 

scenario modeling shows that the greatest potential for contamination occurs only during “start 
28

up” operations in a given area, that given area may be a good location for a prospective study 

with the monitoring designed to coincide with the onset of HF operations. 

The SAB notes that the scenario evaluation focus does not cross all research questions 

(according to the tables in the appendices of the EPA’s draft Study Plan). For example, the 

potential effects of water acquisition on drinking water quality are not included in scenario 

evaluation. Since that potential effect is also not incorporated extensively in the case studies, the 

SAB is concerned that it might be neglected. Similarly, no scenario evaluation is proposed for 

research on flowback and produced water and its disposal. The SAB recommends that modeling 

to evaluate scenarios be used across all research questions identified. Further, the SAB notes the 

central role that modeling studies play in designing monitoring, laboratory work and even what 

is addressed in the case studies. Scenario evaluation can be a unifying driver for the study by 

integrating the different approaches to focus on a key set of answerable questions. 

EPA should assess EPA’s 2009 guidance on application of models (U.S. EPA, 2009) to help 

identify factors that should be assessed when selecting which environmental models to use in the 

study. 

Analysis of Existing Data 

Although the draft Study Plan describes analysis of existing data as a key starting point for the 

research plan, the details of this approach are unclear. Chapter 5 provides only brief details, 

while Figure 9a (see Appendix D) shows this as a significant part of the draft Study Plan. The 

SAB agrees there is significant value to the synthesis of existing data, and that EPA should 

review all available data sources to learn from what is already known about the relationship of 

hydraulic fracturing and drinking water resources. EPA’s 2004 study clearly documented the 

lack of existing data and thus EPA should identify what new data are available and better 

articulate applicability of the new data to the research questions. In the response below, SAB 

provides citations for additional literature that EPA should assess in order to ensure a 

comprehensive understanding of the trends in the hydraulic fracturing process and the potential 

impacts of hydraulic fracturing on drinking water resources. The Panel discussed at length the 

limitations of the small data set that will be generated from the limited number of case studies 

that will be conducted in the available time and budget. These limitations suggest the analysis of 

all existing available data will be even more critical to answer the research questions identified. 

The SAB recommends EPA more carefully consider the nature and extent of existing data in this 

field, and provide details of the planned analysis of these data. For example, the SAB 

recommends looking at (1) data on existing source water conditions and the water quantity and 

quality needed for ecological ("environmental") flows, (2) data on existing well technologies, 

and (3) data on existing disposal technologies. 

Field and Laboratory Methods 

Overall the draft Study Plan inadequately describes the field and laboratory methods that will be 

utilized and thus provides insufficient information to allow full evaluation by the SAB. Field 

monitoring is not well described, and the laboratory scale experimentation and analysis was only 

briefly described in the draft Study Plan. The modeling components do not fully address the 
29

physical mechanisms that could be encountered, such as density-dependent flows, thermallyinduced flows, and surface-water–groundwater interactions. The use of isotopic analysis is 

mentioned for both gas and water analysis but the SAB concludes that more detail is needed to 

assess this approach. 

In several sections of the Study Plan, EPA recommends the development of separate analytical 

methods for detecting chemicals associated with hydraulic fracturing events. The SAB 

concludes that there is insufficient time or resources to develop new analytical methods during 

this study. The SAB recommends EPA employ known methods and use scenario modeling and 

mass balances to identify worst case outcomes. It would be helpful if EPA identified 

conservative or persistent indicator chemicals common to most or all fracturing fluids to narrow 

the analytical focus.

3.3.3. Additional Literature

Additional literature that EPA should assess to ensure a comprehensive understanding of the 

trends in the hydraulic fracturing process, and the potential impacts of hydraulic fracturing on 

drinking water resources, include the following:

Alberta Environment. Water management framework: Instream flow needs and water 

management system for the lower Athabasca River. 2008. Alberta Environment and Fisheries 

and Oceans Canada. July 31,2008. 

http://environment.alberta.ca/documents/Athabasca_RWMF_Technical.pdf. 

American Petroleum Institute. Overview of Exploration and Production Waste Volumes and 

Waste Management Practices in the United States. 2000. American Petroleum Institute. 

http://www.api.org/aboutoilgas/sectors/explore/waste-management.cfm. 

Blauch, M.E., R.R. Myers, T.R. Moore, B.A. Lapinski, and N.A. Houston. Marcellus shale postfrac flowback waters – where is all the salt coming from and what are the implications? 2009. 

Presented at 2009 Society of Petroleum Engineers International Conference, Charleston, WV. 

SPE Paper # 125740. September 23-25, 2009.

Chen, G., M.E. Chenevert, M.M. Sharma, and M. Yu. A study of wellbore stability in shales 

including poroelastic, chemical, and thermal effects. 2003. Journal of Petroleum Science and 

Engineering 38 (3-4): 167-176.

Chenevert, M.E., and M. Amanullah. Shale Preservation and Testing Techniques for BoreholeStability Studies. 2001. Journal of Society of Petroleum Engineers Drilling & Completion

16(3): 146-149.

Cheung, K., Klassen, P., Mayer, B., Goodarzi, F., and Aravena, R. Major ion and isotope 

geochemistry of fluids and gases from coalbed methane and shallow groundwater wells in 

Alberta, Canada. 2010. Applied Geochemistry 25: 1307-1329.
30

Clark, C.E., and J.A. Veil. Produced Water Volumes and Management Practices in the United 

States. 2009. U.S. Department of Energy, Office of Fossil Energy, Argonne National 

Laboratory National Energy Technology Laboratory, Environmental Science Division. 

ANL/EVS/R-09/1. http://www.evs.anl.gov/pub/dsp_detail.cfm?PubID=2437. 

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Proposed Research Activities - Water Acquisition

Charge Question 4(a): Proposed research activities are provided for each stage of the 

water lifecycle and summarized in Figure 9. Will the proposed research activities 

adequately answer the secondary questions listed in Table 2 for the Water Acquisition stage 

of the water lifecycle? Please provide any suggestions for additional research activities.

3.4.1. General Comments

To address the research questions listed in Table 2 (see Appendix B) and summarized in Figure 9 

(see Appendix D) for the Water Acquisition stage of the water lifecycle, EPA plans to conduct 

the following activities:

• Conduct retrospective and prospective case studies. 

• Analyze and map water quality and quantity data.

• Assess impacts of cumulative water withdrawals. 

The SAB finds that the proposed activities will, in general, adequately address the research 

questions associated with this lifecycle stage as outlined in Table 2. However, the SAB 

recommends that the draft Study Plan include an additional desired research outcome to collect 

baseline hydrologic and water quality data in each prospective case study before HF activity 

begins, so that significant changes in water availability or water quality caused by HF activity 

can be more readily documented. EPA should develop a “vulnerability index” or a list of criteria 

that could be used in the future to indicate situations where a water supply is vulnerable to 

adverse impacts on water quality or quantity, and identify where further evaluation may be 

warranted. 

Further, the SAB recommends that EPA provide more details or broaden the scope of work 

aimed at understanding the cumulative effects of water withdrawals on water availability. The 

proposed work uses only scenario analysis and modeling to provide a first approximation of the 

effects of large water withdrawals. Attention should be given to quantifying the role of this 

water use on both surface water and groundwater, and to quantify thresholds of change that 

would lead to transient and permanent effects on water availability. Though the proposed 

modeling includes scenarios under wet through dry conditions, the use of frequency analysis 

with data from existing streamflow monitoring stations should be expanded in this context. For 

example, EPA should use flow duration curves and flood frequency curves to help understand 

the natural variability in flows. This can help to quantify the role of both the timing and 

magnitude of small and large water withdrawals in the context of probable hydrological 

variability. Also, this can be used to highlight the fact that water withdrawals can adversely 

affect even wetter regions of the country (e.g., Pennsylvania) during periods when rainfall is 

significantly less than normal. 

The SAB recommends that EPA’s list of analytes (provided in Table G1 of the draft Study Plan) 

that would be studied to assess the potential impacts of water acquisition and other hydraulic 

fracturing activities on water quality should specifically include the following constituents: 

hydrogen sulfide, ammonium, radon, iron, manganese, arsenic, selenium, total organic carbon, 
36

and bromide. In addition, EPA should also assess the potential of constituents in HF-impacted 

waters to form disinfection by-products (including trihalomethanes, haloacetic acids, other 

halogenated organic compounds and disinfection by-products formed by other disinfecting 

agents such as ozone and chloramines) in drinking water treatment. 

The SAB recommends that EPA include consideration of HF water quality parameters for which 

Maximum Contaminant Levels (MCLs) have not been established under the Safe Drinking 

Water Act, in addition to the proposed parameters for which MCLs have been established. Since 

MCLs have not been established for some of the chemicals used in the HF process, MCLs alone 

will not be sufficient for assessing all potentially significant impacts of hydraulic fracturing on 

drinking water quality. EPA should also examine trends in water quality associated with HF 

water acquisition and determine whether adverse impacts will result if these trends continue.

The SAB has a number of specific comments noted below associated with this lifecycle stage. 

Additional specific comments on the research questions for this lifecycle stage are included 

within this Report’s response to Charge Question 2.

Advances in membrane desalination, increasing use of aquifer storage and recovery systems, and 

regional water shortages are changing perspectives on what constitutes a source of drinking 

water. The SAB recommends that EPA not automatically exclude from consideration potential 

impacts on a water source having more than 10,000 mg/L of total dissolved solids if it could 

reasonably be anticipated to be a viable source of water supply in the future.

3.4.2. Specific Comments

The draft Study Plan does not explicitly address the obstacles private well owners and small 

public water supply systems (PWSSs) may encounter if they experience adverse impacts on 

water availability or water quality that they believe are related to HF activities. Unlike larger 

users, private well owners and small PWSSs will generally lack the financial resources to hire 

experts to prove that their water resources have been adversely impacted. This problem is 

related to both management practices and environmental justice (as discussed in Section 9 of the 

draft Study Plan), and is an issue for anyone whose private well is impacted. The SAB 

recommends that the draft Study Plan include an additional desired research outcome to develop 

a recommended protocol for collecting baseline hydrogeologic and water quality data in each 

prospective study area before HF activity begins, so that significant changes in water availability 

or water quality caused by HF activity can be more readily documented. EPA should develop a 

“vulnerability index” or a list of criteria that could be used to indicate situations where a water 

supply is vulnerable to adverse impacts on water quality or quantity, , and identify where further 

evaluation may be warranted. 

EPA’s list of analytes to be considered in studying the potential impacts of water acquisition 

(and other HF activities) on water quality (Table G1) should explicitly include: 1) hydrogen 

sulfide, a toxic and corrosive substance that also imparts a strongly offensive odor to air and 

water, exerts an oxygen demand in streams, and exerts a high oxidant demand (e.g., chlorine 

demand) when present in a public water supply; 2) ammonium, a compound naturally present in 

many alluvial aquifers and some deeper formation that exerts a large chlorine demand and is also 
37

toxic to many aquatic organisms; 3) radon, a radioactive gas that could potentially be released 

into drinking water by HF activities; 4) iron, manganese, arsenic, and selenium, constituents that 

may be mobilized by HF activities, including water withdrawal; and 5) total organic carbon 

(TOC), bromide and potential disinfection by-product precursors that can form trihalomethanes, 

haloacetic acids, and other halogenated organic compounds when present in source waters that 

are treated with chlorine-based disinfectants. 

The SAB concludes that since proprietary and/or new chemicals are used in the HF process for 

which no Maximum Contaminant Levels (MCLs) under the Safe Drinking Water Act have been 

established, MCLs are not sufficient for assessing all potentially significant impacts on drinking 

water quality. For example, changes in nutrient or carbon loading to a stream that do not directly 

cause an MCL to be exceeded can still cause changes in water quality, such as increased 

production of taste- and odor-causing compounds or disinfection by-product (DBP) precursors, 

resulting in increased treatment costs or degradation of drinking water quality. An increase in 

bromide in source waters may cause an increase in cancer risk (if more carcinogenic brominated 

species are preferentially formed) even if the MCLs for DBPs are not exceeded. A significant 

increase in the chloride concentration can cause considerable economic loss to a community 

even if the secondary MCL for TDS of 500 mg/L is not exceeded. Therefore, the SAB 

recommends that EPA include in its analysis parameters for which MCLs have not been 

established, in addition to the proposed parameters for which MCLs have been established. EPA 

should also include potential impacts on water quality that do not involve MCL exceedances. 

When assessing the fate and mass balance of potential contaminants associated with hydraulic 

fracturing operations, EPA should assess the potential release of contaminants to the air, in order 

to close the mass balance. Such releases, with subsequent deposition to surface water resources, 

could potentially result in contamination of water supply sources, and thus their magnitude 

should be estimated to determine if further study is warranted. Further, it is important to note 

that unhealthy exposures can result from breathing air containing chemicals volatilized from 

potable water (such as in the shower), as well as through consumption and potentially other 

exposure routes. These indoor air exposures associated with potable water are within the scope 

of traditional drinking water research and should be considered. 

EPA should also examine trends in water quality associated with HF water acquisition and 

determine whether adverse impacts will result if these trends continue, e.g., if HF water 

acquisition activities continue to increase in the area up to the maximum level that can be 

reasonably expected. 

The draft Study Plan states (p. 1) notes that for EPA’s study, EPA defines “drinking water 

resources” to be any body of water, ground or surface, that could currently, or in the future, 

produce an appropriate quantity and flow rate of water to serve as a source of drinking water for 

public or private water supplies. This includes both underground sources of drinking water 

(USDWs) and surface waters. USDWs are defined in the glossary as aquifers capable of 

supplying a public water system and having a TDS concentration of 10,000 mg/L or less. It is 

reasonable to consider very deep, highly saline aquifers isolated from drinking water resources as 

potential sites for waste injection, but shallower brackish waters are increasingly being 

considered as potential sources of supply, especially in more arid areas of the U.S. Due to 
38

advances in membrane desalination, even seawater is now considered as a potential source of 

water supply, as exemplified by the membrane desalination plant operated by Tampa Bay Water 

and similar plants being planned or designed in California, Texas, and other locations . 

Furthermore, some relatively saline aquifers may be suitable for use in future “aquifer storage 

and recovery” operations. The SAB recommends that EPA not automatically exclude from 

consideration potential impacts on a water source having more than 10,000 mg/L of total 

dissolved solids if it could reasonably be anticipated to be a viable source of water supply in the 

future. The SAB is not proposing that EPA expand the scope of the study to intentionally look 

for opportunities to evaluate such cases.
39

Proposed Research Activities - Chemical Mixing

Charge Question 4(b): Proposed research activities are provided for each stage of the 

water lifecycle and summarized in Figure 9. Will the proposed research activities 

adequately answer the secondary questions listed in Table 2 for the Chemical Mixing

stage of the water lifecycle? Please provide any suggestions for additional research 

activities.

3.5.1. General Comments

To address the research questions listed in Table 2 (see Appendix B) and summarized in Figure 9 

(see Appendix D) for the Chemical Mixing stage of the water lifecycle, EPA plans to conduct the 

following activities:

• Conduct retrospective and prospective case studies. 

• Compile a list of chemicals used in HF fluids.

• Identify possible chemical indicators and analytical methods.

• Develop additional analytical methods.

• Review scientific literature on surface chemical spills.

• Identify known toxicity of HF chemicals.

• Predict toxicity of unknown chemicals

• Develop Provisional Peer-Reviewed Toxicity Values (PPRTVs) for chemicals of 

concern. 

The SAB concludes that, overall, EPA has generally proposed a sound approach to address the 

research questions associated with this lifecycle stage as outlined in Table 2. The SAB has some 

recommendations for specific components of the research plan that could be strengthened as 

described further below.

The SAB supports EPA’s proposed approach to analyze existing data rather than collecting 

samples for analysis to assess HF fluid composition and toxicity of fluid components, and agrees 

that EPA’s effort to gather data from nine hydraulic fracturing service companies will likely 

provide sufficient information on the composition of HF fluids. Appendix C of the Draft Plan 

indicated that all companies have agreed to comply with the request and that information would 

be submitted by January 2011. Nearly all the information received by EPA was designated as 

confidential business information (CBI). EPA is currently reviewing the CBI claims. 

Information that was not claimed to be CBI has been made available to the public in the EPA 

Docket, at the following website address: http://www.regulations.gov, and the docket number is: 

EPA-HQ-ORD-2010-0674. SAB recommends that EPA also gather HF fluid composition data 

from states collecting such data, and consider the role that recycling and reuse of HF fluids will 

play in influencing both quantity and composition of HF fluids. 

Specific comments on exposure analyses, hazard identification , toxicity testing, analytical 

methods, and indicators of contamination are included within this Report’s response to Charge 

Question 2. The SAB finds that EPA should give low priority to development of analytical 

methods for specific components for which there are no existing EPA-approved methods due to 

time and budget limitations.
40

The SAB generally supports EPA’s plans to identify factors that influence the likelihood of 

contamination of drinking water resources as a result of chemical mixing activities. Although 

SAB agrees that EPA will identify a number of factors that influence the likelihood of 

contamination of drinking water resources as a result of chemical mixing activities, the list of 

factors may not be complete, the project time and budget may not allow time for a complete 

evaluation of the factors, and the results should not be generalized across all HF sites. 

The SAB does not agree that case studies alone will provide sufficient information regarding 

effectiveness of mitigation approaches in reducing impacts to drinking water resources. SAB 

recommends that EPA analyze data from HF service companies and states in order to provide 

additional insight. The retrospective case studies may also be a source of useful information 

about approaches that failed to prevent or control impacts.

The SAB has a number of specific comments noted below associated with this lifecycle stage. 

Additional specific comments on the research questions for this lifecycle stage are included 

within this Report’s response to Charge Question 2.

3.5.2. Specific Comments 

 

What is the composition of hydraulic fluids and what are the toxic effects of these constituents?

The draft Study Plan indicated that the approach to be used in answering the question about 

composition of HF fluids and toxicity of the components will be to analyze existing data. The 

SAB agrees that EPA’s effort to gather data from nine hydraulic fracturing service companies is 

an approach that is likely to answer the question on composition of HF fluids. The SAB supports 

the analysis of existing data rather than reverse engineering of collected samples of fluids in 

order to assess HF fluid composition and toxicity of fluid components. Given the size of the 

companies and their geographic coverage, a comprehensive list of the composition of HF fluids 

is anticipated. The level of detail requested should provide the EPA with data adequate to 

answer the question. The SAB notes that a few states are collecting relevant data either as a 

requirement of permitting (e.g., Wyoming) or on a voluntary basis (e.g., Pennsylvania) that can 

be of use to the EPA for this question. The SAB also recommends that EPA consider the role 

that recycling and reuse of HF fluids will play in composition. SAB recommends that EPA 

consider assessing how to reduce the potential adverse effects of additive chemicals, and options 

to encourage development of ‘greener’ HF additives and HF methods, perhaps through 

partnership with the U.S. Department of Energy (DOE).

Specific comments on hazard identification, exposure assessment, toxicity testing, analytical 

methods, and indicators of contamination are included within this Report’s response to Charge 

Question 2. The SAB finds the development of potential chemical indicators of contamination 

an appealing approach. The consensus of the SAB is that it may be difficult to achieve a 

practical indicator approach within the time allotted for the study. The EPA can likely develop a 

list of possible indicators for which analytical methods exist that can be tested in the prospective 

case studies and scenario modeling. Tracers that can be added might be another tactic to 

consider but must take into consideration public and industry concerns about such an approach.
41

The SAB also recommends that development of analytical methods for specific components for 

which there are no existing EPA-approved methods should be given a low priority due to cost 

and time constraints. The EPA should focus on existing methods for the near term effort and 

develop a list of priorities for future efforts based on the first-order hazard assessment.

The U.S. House of Representatives Committee on Energy and Commerce Minority Staff 

provided a recent document (U.S. House of Representatives, 2011) on ‘Chemicals used in 

Hydraulic Fracturing’ which lists a large number of chemicals used in HF fluid reported by a 

number of drilling companies.

This report indicates that companies using these fluids purchase them from third party suppliers 

and the proprietary information belongs to those suppliers, and may provide important detailed 

information about chemical constituents of HF fluids. . 

In addition, the Ground Water Protection Council (GWPC) and the Interstate Oil and Gas 

Compact Commission (IOGCC), with funding support from the DOE, unveiled a web-based 

national registry on April 11, 2011, disclosing the chemical additives used in the hydraulic 

fracturing process on a well-by-well basis (www.fracfocus.org). EPA should assess these data 

when assessing the composition and toxicity of HF fluids. The information on the web site 

covers wells drilled starting in 2011. A fact sheet on the effort is available from the State of 

Oklahoma (http://www.iogcc.state.ok.us/national-registry-provides-public-and-regulatorsaccess-to-information-on-chemical-additiv).

What factors may influence the likelihood of contamination of drinking water resources?

The SAB concludes that the EPA will be able to identify a number of factors that influence the 

likelihood of contamination of drinking water resources as a result of chemical mixing activities, 

but the list of factors may not be complete and should not be generalized across all HF sites. The 

EPA indicated that it will analyze existing data and use the retrospective case studies to answer 

this question. The SAB expresses support in general for the planned approach to answering this 

question. The information request to the nine HF services companies will likely provide input on 

some of the factors (e.g., total quantities used, chemical and physical properties of components, 

etc.). The EPA will also search the existing literature for research about potential contamination 

of drinking water resources using the list of chemicals supplied through the information request. 

The states may provide information about the spills that may have affected drinking water 

resources. The SAB supports EPA’s plan to develop a list of the knowledge gaps about factors 

influencing the contamination of drinking water resources as a result of chemical mixing 

activities for future research efforts. The SAB is concerned that several factors will be site 

specific and difficult to generalize across the range of geographical areas that are involved in HF 

activities. The SAB recommends that the EPA will need a full understanding of all the activities 

involved such as the cleaning of mixing vessels or tanker trucks and handling of the wash water. 

The SAB notes that the prospective case studies are potentially useful in answering this question; 

however, the SAB also notes that the best management practices examined in these case studies 

will not necessarily be used at other sites. The number of retrospective and prospective case 

studies that can be evaluated in the given time will be limited, which will not allow for 

generalization from the data gathered.
42

How effective are mitigation approaches in reducing impacts to drinking water resources? 

The SAB expresses concern that the prospective case studies alone will not provide adequate 

answers for this question. The partners involved in the prospective case studies will likely 

follow best management practices and take extra precautions, the impact of which will be 

difficult to assess. There is concern that the number of case studies planned might be insufficient 

to span the range of geological and hydrological regimes where drilling is active or anticipated. 

There is concern that the case studies may ultimately be too limited in scope for results to be 

applied generally. Thus, the Panel discussed the total number of case studies needed to yield 

useful data for the research program, and whether a statistically acceptable number of case 

studies could or should be undertaken to meet the research objectives. The SAB did not reach 

consensus on this point because the specific objectives of these case studies are unclear. As the 

study moves forward, it is important for EPA to explain the rationale for the selected case 

studies. The analysis of data supplied by the HF service companies and states may be helpful in 

providing additional insight. The retrospective case studies may be a source of useful 

information about approaches that failed to reduce impacts. However, overall the SAB is not 

convinced that this question can be adequately addressed through the Study Plan. 
43

Proposed Research Activities - Well Injection

Charge Question 4(c): Proposed research activities are provided for each stage of the 

water lifecycle and summarized in Figure 9. Will the proposed research activities 

adequately answer the secondary questions listed in Table 2 for the Well Injection stage 

of the water lifecycle? Please provide any suggestions for additional research activities.

3.6.1. General Comments

In order to address the research questions listed in Table 2 (see Appendix B) and summarized in 

Figure 9 (see Appendix D) for the Well Injection stage of the water lifecycle, EPA plans to 

conduct the following activities:

• Conduct retrospective and prospective case studies. 

• Analyze well files

• Test well failure and existing subsurface pathway scenarios

• Study reactions between HF fluids

• Identify known toxicity of naturally occurring substances

• Predict toxicity of unknown chemicals

• Develop Provisional Peer-Reviewed Toxicity Values (PPRTVs) for chemicals of 

concern. 

The SAB does not agree it will be possible to cover all facets of the proposed research within the 

time allotted for the research activities and recommends that EPA narrow the scope of activities 

associated with specific case studies and site investigations and use a wide variety of sources 

available to EPA in order to increase the success of the research program. With the cooperation 

of service companies, full access to data, and careful selection of case studies, the SAB 

concludes that the proposed research can adequately address most of the fundamental questions 

associated with possible impacts of the injection and fracturing processes on drinking water 

resources, even with this more narrow scope. The SAB provides a number of specific 

recommendations for focusing EPA’s fundamental and secondary research questions associated 

with this topic area. The SAB recommends that EPA should research well drilling and 

cementing practices separately from the hydraulic fracturing process. 

The SAB has a number of specific comments noted below associated with this lifecycle stage. 

Additional specific comments on the research questions for this lifecycle stage are included 

within this Report’s response to Charge Question 2.

3.6.2. Specific Comments

Fundamental Research Question

The fundamental research question addressed under the topic of well injection is “What are the 

possible impacts of the injection and fracturing process on drinking water resources?” 

Addressing this fundamental question involves establishing different degrees of risk. There are 

different risks dependent on different geologic and hydrogeologic conditions requiring a 

prioritization of research to be conducted. By conducting retrospective and prospective case 
44

studies as outlined in the draft Study Plan the various risk factors and their interdependence can 

be evaluated. While not totally encompassing and thus unable to cover all possible impacts, the 

research will aid in addressing the fundamental research question pertaining to possible impacts. 

As a starting point, the SAB recognizes that there are three escape mechanisms during well

injection such that contaminants might affect drinking water: escape through the well, through 

the cement surrounding the well, and as a result of various steps of the hydraulic fracturing 

process itself. Assuming drilling and cementing practices for HF wells are not different from 

practices for other industry wells, the consensus of the Panel is that well drilling and cementing 

practices be researched separately from the hydraulic fracturing process itself. In doing so, the 

SAB concludes the EPA can better focus on the question of the potential influence of the 

hydraulic fracturing process on drinking water resources and contamination of aquifers. 

Since groundwater can potentially be contaminated by HF during well injection (including 

leakage from the injection wells, leakoff during hydraulic fracturing along faults or up 

abandoned wells), the possibility of exposures through potential groundwater contamination 

should be assessed. The SAB also recognizes that while discharges to surface water can also 

lead to exposures, they tend to be transient. Groundwater contamination is more likely to lead to 

long-term contamination and long-term exposure. In addition, groundwater is preferentially used 

as a source of supply by smaller utilities and communities (including rural communities) and by 

the majority of non-community water systems. Many such supplies are only minimally 

monitored, and their owners often lack the resources for independent protection of the aquifers 

from which their supplies are drawn. Unlike surface waters, groundwater is susceptible to 

contamination by methane and radon, and groundwater is more susceptible to contamination by 

volatile organic contaminants, including the Benzene, Toluene, Ethylbenzene, and Xylenes 

(BTEX) compounds that have reportedly been used at times to prepare HF fluids or may come 

from the formation itself. EPA will be obtaining information as the study progresses and should 

use its expertise to set priorities for these and other pathways as needed. 

Secondary Research Questions

Discussion under item 4(c) focused on four secondary research questions:

1) How effective are well construction practices at containing gases and fluids before, during 

and after fracturing?

The SAB concludes that EPA’s research activities regarding well construction practice should be 

split into two categories – the drilling, cementing and completion practices (i.e., well bore 

integrity during construction) versus the fracturing process itself. Regulatory agencies in some 

states may have access to data on well bore integrity that can enable the EPA to address specific 

examples of well bore and well failure. The SAB suspects that the data will be ‘spotty’, 

however, and may vary from state to state. The value of ‘mining’ such data may be in the 

retrospective case studies to evaluate risk. It will be area and site dependent. In addition, there 

are thousands of underground injection wells currently that are controlled by the Underground 

Injection Control Program (UIC) that can shed light on the general topic of well bore and well 

integrity. The Study Plan should define the data that would be collected to assess well failure 
45

and relate relevant factors particularly associated with HF operations into a risk assessment 

model. The Study Plan should also be specific about how the frequency of well failures will be 

determined because the method to be used is not obvious in the draft Study Plan. The well 

architecture itself is shifting away from vertical wells to highly deviated wells with multi-zone 

completions. EPA may have to specifically focus and direct its research activities based on well 

type in order to adequately evaluate the effectiveness of well construction practices and the risk 

of contamination of groundwater resources.

The hydraulic fracturing process needs to be addressed separately. The SAB recommends that 

EPA conduct research on factors such as depth of the hydraulic fracturing and proximity to 

underground aquifers, the geology of the subsurface, the hydrogeologic framework, stresses in 

the subsurface, the fluids and their amendments used in the process, and the interaction with the 

rock and fluids in the subsurface. By addressing these factors in a systematic manner through 

the use of case studies, modeling and laboratory analyses, risk assessment modeling may be 

undertaken to prioritize risk related to the HF process itself.

In the case studies EPA could provide special focus on the key factors necessary in establishing a 

risk assessment model. A shortcoming of this approach is that typical risk assessments do not 

include the potential for catastrophic failure (e.g., earth motions competent to break water supply 

lines). EPA should assess the potential for catastrophic failure within the scenarios assessed 

within the case studies, since treating end members within a risk assessment model can aid in 

creating transparency and hazard preparedness. Modeling the hydraulic fracture process through 

finite difference or finite element mathematical modeling may give insights into criteria for 

establishing risk. 

Finally, EPA should be sure to include case study sites where hydraulic fracturing is being 

conducted in relatively shallow environments in proximity to drinking water aquifers. 

Microseismic monitoring, if available, could be used to help create appropriate fracture models. 

In areas of variable topography, underground mining, or in karst regions within the subsurface, 

stress variances can induce a variation in fracture growth. 

2) What are the potential impacts of pre-existing artificial or natural pathways/features on 

contaminant transport?

The SAB generally agrees that geologic and hydrogeologic characterization is necessary, but 

notes this is a difficult task to undertake and complete with sufficient detail to inform subsurface 

transport models especially within the limits on budget and time for the study. The SAB 

recommends that EPA’s first step should be to focus on specific areas where the most complete 

data on these topics are available. The SAB also recommends that EPA use the resources of 

other governmental agencies such as the U.S. Geological Survey to address subsurface 

characterization and to establish analogous injection sites (e.g., carbon dioxide sequestration 

projects). Site characterization is an essential ingredient of determining the viability of sites to 

store carbon dioxide. The DOE may be able to provide EPA with information on stresses in the 

subsurface, which is a significant factor to consider. It is also essential for EPA to establish 
46

stress profiles and determine the mechanical stratigraphy and hydrological properties of the case 

study areas. Generally, the data are available to engage in site characterization as part of the case 

studies that will be selected and undertaken. 

The SAB concludes that a major concern to be addressed is the presence of faults in the 

subsurface. Not all faults are transmissive in nature, and numerous studies have documented 

faults as seals or sealing faults. The SAB notes that a key concern is what happens when there is 

injection near a fault. Generally, it is industry practice to avoid faults by conducting reflection 

seismic profiling to identify faults. These studies are often conducted for purposes of 

geosteering to avoid faults and drilling out of zone. However, sub-seismic faults exist, making it 

difficult to avoid faults altogether. Microseismic monitoring can assist in determining what 

happens if a hydraulic fracture is conducted near a fault. EPA should gather available seismic 

profile data to assist in evaluating the potential for releases to underground sources of drinking 

water. Whether or not the fault is transmissive requires other forms of study including transient 

pressure testing.

The SAB recommends that EPA identify a shallow site known to have faults as one of the 

prospective case studies. The SAB expresses concern about fracture fluids propagating in fault 

and fracture zones. These fluids can occur in gaseous or liquid state and have different mobility 

and flow characteristics. Mobile gases can move along fault and fractures zones in a relatively 

short time; liquids will take longer to move than gases. Different fluids create different potential 

problems and a variety of scenarios needs to be investigated. The SAB recommends that EPA 

focus additional research on the different fluids associated with the hydraulic fracturing process. 

The SAB recommends that EPA conduct soil geochemistry studies which may shed light on the 

question of vapor transport associated with the hydraulic fracturing process. 

The SAB recognizes that the use of a chemical tracer may aid the monitoring effort, but notes 

that the tracer would have to be carefully and judiciously chosen. The tracer design must be 

unique, unambiguously related to the hydraulic fracturing process, uniquely identifiable, readily 

measurable at substantial dilutions, non-toxic and non-reactive. 

The SAB concludes that long term monitoring is preferred over short term monitoring with 

respect to monitoring of HF impacts on water resources. The SAB recognizes that EPA may 

have difficulty in precisely determining cause and effect associations within the monitoring 

networks, for various reasons. If fractures are only opened during the hydraulic fracturing 

process, a very short time period for mobilization can occur. In low permeability formations, 

however, it may take considerable time for pressure to abate. Fluid flow in these low 

permeability reservoirs is non-Darcy flow involving diffusion. Upon production, pressure 

drawdown occurs and fractures usually close over time. EPA should assess the seismic 

conditions that create changes in subsurface geology of the formation (e.g. Marcellus Shale) 

which are created by the perforated gun-shoot holes through the casing and the application of 

pressure. Long term monitoring is a key aspect to assuring that these fractures do not cause 

contamination to groundwater and preferential flow pathways into and for ground water 

migration and contamination. In addition, abandoned wells and mines are potential primary 
47

conduits to near surface aquifers as well as surface waters. The identification of abandoned 

wells is problematic, and the SAB recommends that EPA assess the role these wells and old 

mine workings play in certain parts of the country relative to hydraulic fracturing operations.

The SAB encourages EPA to consider expanding its emphasis on hydraulic fracture mapping. 

There are many local issues tied to formation geology, vertical depth between aquifers and 

formations being fractured, and the existence of karst formations or naturally occurring regionalfracture systems that may enhance hydrogeologic communication after fracturing is completed. 

Much work has taken place in the private sector on this. Advances are being made in microseismic testing and interpretation, use of tiltimeters, and fracture network mapping and 

modeling. The SAB recommends that EPA carefully examine this issue as it develops its case 

studies. EPA should also consider collaborating with DOE and the U.S. Geological Survey to 

convene workshops on advanced hydrofracture mapping technology development and new 

technology applications, to help increase the knowledge base on such new geophysical 

techniques and hydrogeologic testing methods.

3) What chemical/physical/biological processes could impact the fate and transport of 

substances in the subsurface?

The SAB highly recommends that EPA pursue efforts to identify the chemicals used in the 

hydraulic fracturing process and their chemical and physical properties. Biological processes 

and the details regarding how the biological impact will be investigated are unclear in the draft 

Study Plan. 

A major concern is the reaction of the injected chemicals within the formations and whether 

these reactions increase the potential for contamination of water resources in a given area. This 

information would aid in the determination of risk factors and assist the development of a risk 

assessment process. The primary composition of the chemicals used in the hydraulic fracturing 

process and their interaction with the natural compounds in the subsurface need to be addressed 

in this study. Research should also address the potential transformations of products formed 

from reactions of HF fluids with formation materials. 

The Study Plan implies that this research would only involve laboratory studies. The SAB finds 

that the results may not be representative of what happens in the field. SAB recommends that 

analysis of samples collected in conjunction with the case studies be included in answering this 

question in addition to the laboratory studies. SAB also recommends that modeling be 

conducted to assist in answering this question, if there are models available that can predict the 

decomposition products from reactions of HF fluids with formation materials.

4) What are the toxic effects of naturally occurring substances?

EPA’s proposed research activities can answer the question about the known toxic effects of 

naturally occurring substances that have been evaluated previously (e.g., radon, hydrogen 

sulfide, and selenium) by compiling existing toxicity information. As discussed in this Report’s 

response to Charge Question 2, the SAB cautions EPA on spending resources on evaluating the 

toxicities of substances unless EPA knows that the probability of exposure to a particular 
48

substance is high. The SAB also notes that Table 5 is fairly general and does not include radon 

or ammonia and that Table D2 should be included in the discussion in Section 6.3.5. Specific 

comments on hazard identification, exposure assessment, toxicity testing, analytical methods, 

and indicators of contamination are included within this Report’s response to Charge Question 2. 

The SAB also recommends that EPA consider hazard broadly and include risks that these 

substances may have (explosions) that are not due to toxicity. EPA should also acknowledge 

importance of any aesthetic impacts that both naturally occurring and well-injection derived 

substances may have on drinking water quality. 

Recommendations for Additional Research Activities

The SAB provides the following recommendations for additional research activities:

1) Conduct a case study involving seismic and groundwater monitoring in a highly stressed area 

involving faults within 1000 feet of wells undergoing hydraulic fracture treatment. The 

purpose of this recommendation is to emphasize the complex interplay between natural 

fractures within a formation and its response to hydraulic fracture treatment. In shales in 

particular, the stress-dependence of the permeability of natural fractures, as well as the 

permeability generated by shear fracturing that may develop, are the dominant features that 

control fluid flow and potential fluid mobility pathways. See Maxwell et al. (2011).

2) Identify and characterize common and best practices for well construction (e.g., casing 

design, construction under different scenarios, settings, failure rates, life expectancies, and 

performance of cements under a variety of hydraulic fracturing conditions) and monitoring, 

and determine whether such practices meet minimum standards from a public water supply 

perspective. Exploration wells represent permanent establishment of potential means of 

hydrogeologic communication between formations and aquifers and the incidence of well 

completion failure, especially around annulus cementing through the aquifer, and such 

incidences need to be well understood. EPA should gather available information on this 

topic from the American Petroleum Institute and the National Ground Water Association. 

3) Research fluids and fluid movements associated with hydraulic fracturing in terms of 

mobility. There are gaseous and liquid states, and potentially even “hybrid” states and 

phases, different flow paths, and different flow mechanisms under different temperature and 

pressure regimes.

4) Review Tables 5, D2 (needs to be included in section 6.3.5), and D3 for completeness (e.g., 

radon is not included). In the future, as discussed in specific comments in this Report’s 

response to Charge Question 2, toxicity studies, if exposure is likely, may need to be 

undertaken.
49

Proposed Research Activities – Flowback and Produced Water

Charge Question 4(d): Proposed research activities are provided for each stage of the 

water lifecycle and summarized in Figure 9. Will the proposed research activities 

adequately answer the secondary questions listed in Table 2 for the Flowback and 

Produced Water stage of the water lifecycle? Please provide any suggestions for 

additional research activities.

3.7.1. General Comments

In order to address the research questions listed in Table 2 (see Appendix B) and summarized in 

Figure 9 (see Appendix D) for the Flowback and Produced Water stage of the water lifecycle, 

EPA plans to conduct the following activities:

• Conduct retrospective and prospective case studies 

• Compile list of chemicals found in flowback and produced water

• Identify or develop analytical methods

• Review scientific literature on surface chemical spills

• Investigate scenarios involving contaminant migration up the well

• Identify known toxicity of HF wastewater constituents

• Predict toxicity of unknown chemicals

• Develop Provisional Peer-Reviewed Toxicity Values (PPRTVs) for chemicals of 

concern. 

The SAB concludes that, overall, EPA has generally proposed a sound approach to address the 

research questions associated with this lifecycle stage as outlined in Table 2. The SAB has some 

recommendations for specific components of the research plan that could be strengthened as 

described further below.

The handling, treatment and disposal of post-fracturing produced water represents an important 

route of exposure and has potential for adverse widespread impacts. Although sometimes 

flowback and 

produced water are mentioned independently, these distinctions are only operational as there is a 

continuous evolution of water quality for post-fracturing produced water. To the extent 

differentiation of flowback and produced water is desired by EPA, the SAB recommends that 

EPA clearly define flowback and produced water in the main body of the Study Plan.

EPA should gather both currently available information on the composition of post-fracturing 

produced water from the hydraulic fracturing process, and proprietary information on all 

additives included in any injected water. The SAB recommends the collection of water quality 

data before, during, and after injection, and from carefully selected locations, including the 

ongoing studies on the quality of surface waters in the regions with significant hydraulic 

fracturing activity. EPA should evaluate quality assurance/quality control (QA/QC) aspects of 

the studies that would be assessed or conducted by EPA. 
50

Specific comments on hazard identification, exposure assessment, toxicity testing, analytical 

methods, indicators of contamination, and on the research questions for this lifecycle stage, are 

included within this Report’s response to Charge Question 2. The SAB has a number of specific 

comments noted below associated with this lifecycle stage. 

3.7.2. Specific Comments

The SAB recommends the handling of liquids that are brought back to the surface during 

hydraulic fracturing operations, such as during surface water management of flowback and 

produced waters and during disposal of treated wastewater, represents an important route of 

exposure and has potential for adverse widespread environmental impacts from the development 

of unconventional gas resources. This is particularly true in situations where Class II 

Underground Injection Control (UIC) wells are not the main disposal alternative. A lifecycle 

approach is an important component of this study, and this lifecycle must be correctly 

characterized. In addition, since groundwater can potentially be contaminated by hydraulic 

fracturing in a number of ways (including leakage from liquid storage areas; leakage from the 

injection wells; leakoff during hydrofracking potentially along faults or up abandoned wells; 

seepage into the ground if hydraulic-fracturing associated wastewaters or residuals from 

treatment of these wastewaters are land applied; facilitated transport for natural gas; and other 

means), potential groundwater contamination is another important opportunity for human health 

exposure. EPA will be obtaining information as the study progresses and should use its expertise 

to set priorities for these and other pathways as needed. 

The SAB agrees with EPA that it is very important to gather information on the composition of 

flowback and produced water from the hydraulic fracturing process, to the extent these data are 

currently available. EPA should contact Publicly Owned Treatment Works (POTWs) who 

accept this water for treatment, accessing the Colorado Oil and Gas Commission database, and 

assessing ongoing DOE National Energy Technology Laboratory projects, particularly since the 

sampling and analysis to be conducted as part of this study would be rather limited. Within the 

human exposure assessment, EPA should assess which chemicals are of primary concern and 

their probability for transport in groundwater and air. The SAB recommends that water quality 

data be collected before, during, and after injection, and from carefully selected locations, 

including the ongoing studies on the quality of surface waters in the regions with significant 

hydraulic fracturing activity. In cases where actual concentrations of contaminants are needed to 

assess potential environmental impacts, including toxic effects, it would be necessary to validate 

QA/QC aspects of the studies that collected these data. It is expected that the prospective case 

studies would follow requisite QA/QC protocols. Development of new analytical techniques 

may be beyond the capability of the proposed study in terms of time and budget; there is likely 

sufficient information in the literature to utilize when conducting sample collection and analysis 

as part of this study.

The Study Plan appears to emphasize the focus of study and research towards shale formations, 

but also notes that coal bed methane and other types of hydraulic fracturing are to be considered 

(Section 2.3). The Study Plan should clarify and specify the research focus for this lifecycle 

stage (i.e., whether the focus for gathering information is on hydraulic fracturing in shale units, 
51

natural gas production, coal bed methane production, other types of hydraulic fracturing activity, 

or a combination of the above). 

The SAB recommends a number of specific research questions under the response to Charge 

Question 2, and provides a few additional recommended specific research questions:

• Inventory types of water being used in hydraulic fracturing to answer questions regarding 

how much high quality water is being used (e.g., water less than 10,000 mg/L TDS) vs. 

lower quality waters.

• Inventory post-fracturing produced water quality for different geographic regions and by 

HF product used to facilitate specific environmental monitoring and improve reporting 

outcomes as well as to inform first responders in the case of spills and leaks and to 

develop necessary management (treatment) approaches as a function of ultimate disposal 

alternatives.

• Consider normal industrial practices at coal bed methane hydraulic fracturing facilities. 

These facilities have documented best management approaches for produced waters, and 

also have identified boundaries for use of and expectations associated with produced 

water quality and hazard scenarios and spills.

• Assess industry practices on containment technologies and releases from pits and liners 

with leaky seals, and describe the “best management practices” for handling flowback 

and produced water during storage and transport of HF materials. 

• The SAB recommends that identification of potential for leaks and spills during storage 

and transport should be based on documented events in the past, which can serve to 

assess the probability for the release of contaminants during different stages of flowback 

and produced water management provided that trends in management practices are taken 

into consideration. 

• Assess potential adverse environmental impacts associated with buried pits and 

impoundments through evaluating the quality of soils and groundwater near such 

structures. 

• The SAB recommends that the disposal of post-fracturing produced water to existing 

POTWs and Centralized Waste Treatment (CWT) facilities needs to be evaluated in 

terms of the fate of key constituents (e.g., chloride, bromide, radium) that may be 

relevant for drinking water treatment facilities downstream of these wastewater treatment 

plants. 
52

Proposed Research Activities - Wastewater Treatment and Waste Disposal

Charge Question 4(e): Proposed research activities are provided for each stage of the 

water lifecycle and summarized in Figure 9. Will the proposed research activities 

adequately answer the secondary questions listed in Table 2 for the Wastewater 

Treatment and Waste Disposal stage of the water lifecycle? Please provide any 

suggestions for additional research activities.

3.8.1. General Comments

In order to address the research questions listed in Table 2 (see Appendix B) and summarized in 

Figure 9 (see Appendix D) for the Wastewater Treatment and Waste Disposal stage of the water 

lifecycle, EPA plans to conduct the following activities:

• Conduct retrospective and prospective case studies 

• Assess existing data on treatment and/or disposal of HF wastewaters

• Identify HF chemical constituents that create disinfection byproducts

• Evaluate potential impacts of high chloride concentrations on drinking water utilities

The SAB concludes that, overall, EPA has generally proposed a sound approach to adequately 

address the research questions associated with this lifecycle stage as outlined in Table 2. The

SAB has some recommendations for specific components of the research plan that could be 

strengthened as described further below.

The Panel strongly recommends the use of scenario modeling, in concert with both retrospective 

and prospective case studies, to “define the boundaries” for activities under this portion of the 

water lifecycle. If dilution is potentially inadequate, then adverse impacts are possible and 

additional treatment may be needed. Scenario modeling involving simple mass balances should 

be conducted as a first-order effort to determine if or when dilution constitutes adequate 

“treatment.” Existing practice in some areas is to discharge return flows to wastewater treatment 

plants and to rely on dilution to “treat” a number of constituents not removed by conventional 

wastewater treatment processes, such as TDS, chloride, bromide, and non-biodegradable organic 

matter. For these constituents, simple calculations can be done to estimate effluent and 

downstream concentrations, which can then be evaluated for their potential to cause adverse 

impacts (not only to humans, via drinking water supplies, but also to other receptors in future 

studies). 

Hydraulic fracturing return flows contain many constituents that are similar to those for which 

treatment technologies exist within the state of practice of industrial wastewater treatment. For 

those constituents, SAB concludes that EPA should conduct a thorough literature review to 

identify existing treatment technologies that are currently being used to treat HF wastewater, 

identify knowledge relevant to hydraulic fracturing return flows, and identify constituents of HF 

return waters that might merit additional attention. SAB recommends that EPA review the 

documented data in the retrospective case studies to assess the efficacy and success of industrial 

wastewater treatment operations and pre-treatment operations for hydraulic fracturing return 

flows. Only a limited number of Publicly Owned Treatment Plants (POTWs) have the ancillary 

treatment technologies needed to remove the constituents in hydraulic fracturing return waters. 
53

SAB recommends that EPA focus its efforts towards literature searches on POTW and industry 

management practices that can minimize the adverse effects associated with certain constituents 

such as TDS, natural organic matter (NOM), bromide, and radioactive species. In addition, EPA 

should assess the need for any special storage, handling, management, or disposal controls for 

solid residuals after treatment. EPA should assess whether land application (e.g., for 

disposal, irrigation, or road application for dust suppression or deicing) of hydraulic-fracturing 

associated wastewaters or residuals from treatment of these wastewaters, which is mentioned in 

the Study Plan, has the potential to affect drinking water resources. 

The SAB encourages EPA to consider measures of pollution prevention associated with 

treatment of hydraulic fracturing wastewaters, and consider developing research questions that 

are built around how to develop technologies and strategies that reduce and eliminate the need 

for treatment and disposal. In addition, in some cases the HF wastes might be reused by 

injection into new wells, and the changes in water quality associated with such reinjection should 

be considered when assessing the composition of the wastes needing treatment. EPA should 

develop proposed research activities related to how the presence of hydraulic fracturing fluids 

impacts issues (social and technological) related to water reuse. Several recent publications of 

the WateReuse Association and WateReuse Foundation may be useful to EPA regarding this 

topic (See Huang and Li, 2009; Salveson, 2009; and Davis, 2009). 

In addition, surface impoundments, holding ponds, and other strategies used for recycling, 

temporary storage, and disposal of HF wastes should be constructed with the best available 

technologies for surface impoundments. EPA’s Surface Impoundment Study highlighted best 

practices for these types of temporary storage scenarios. See U.S. EPA, 2001. EPA’s surface 

impoundment regulations also provide requirements on surface impoundment construction and 

operation/maintenance. See 40 CFR Parts 264/265, Subpart K.

The SAB has a number of specific comments noted below associated with this lifecycle stage. 

Additional specific comments on the research questions for this lifecycle stage are included 

within this Report’s response to Charge Question 2.

3.8.2. Specific Comments

The SAB recommends that the research question itself be reworded to “Are treatment processes 

that are commonly used in water and wastewater treatment plants effective at removing 

constituents of hydraulic fracturing (HF) wastewater, and how do these constituents affect the 

performance of such treatment processes?”

Hydraulic fracturing return flows contain many constituents that are similar to those for which 

treatment technologies exist within the state of practice of industrial wastewater treatment. For 

those constituents, a thorough literature review should be conducted to match treatability studies 

and treatment technologies that are currently being used to treat HF wastewater to hydraulic 

fracturing return flows, and to identify constituents of HF wastes that might merit additional 

attention. The EPA retrospective case studies should review the documented data to assess the 

efficacy and success of industrial wastewater treatment operations and pre-treatment operations 

for hydraulic fracturing wastewater (return flows). Such studies need to critically assess 
54

characteristics of: volumes and flowrates; influent and effluent concentrations; the fate of the 

treated water; management practices, and the disposal of solid residuals. Rather than just a 

handful of retrospective studies as proposed, the full richness of available data should be 

explored. In addition, facilities maintenance (aspects, requirements, frequency, etc.) and cost 

factors (capital, operation and maintenance) at different stages of the life-cycle) need 

documentation. 

Few POTWs are designed to remove many of the contaminants of the hydraulic fracturing 

process. Dissolved solids are not removed in such systems, and in high concentrations they can 

disrupt some unit operations. This phenomenon has been well-studied, so the research on this 

topic should focus on industry management practices that can minimize the adverse effects. All 

POTWs that now accept hydraulic fracturing return flows should be included in the retrospective 

studies in the assessment of the potential impacts of TDS. Similarly, the effects of increased 

NOM and bromide concentrations on disinfection byproducts formation in drinking water 

treatment processes and on corrosion of water distribution networks can be assessed based on a 

thorough literature review and information that the service companies likely have on the salt 

content of the wastewaters. Radioactive species also deserve special attention. Therefore, once 

again, the research should focus on management options to avoid concentrations that lead to 

adverse effects, rather than on studying effects that have already been well characterized. 

The EPA effort should include studying the impact on water treatment plants of the potential 

increased burden of analyzing for contaminants in the treated effluent from any plants (POTWs

or industrial) that treat hydraulic fracturing wastewater and discharge the treated effluent 

upstream of water treatment plants. Controlled release and dilution of the wastewater is one such 

management method and deserves discussion and investigation. If specific contaminants in 

hydraulic fracturing return flows are identified as posing a significant risk to a drinking water 

supply source, then pre-treatment options for those contaminants should be investigated. Also, 

POTW life cycle costs in light of this new stream of wastewater should be addressed. Pilot scale 

testing objectives are in need of articulation.

Solid residuals from POTWs are typically taken to landfills, incinerated, or applied to land (there 

may be some intermediate steps). If some hydraulic fracturing wastewater contaminants are 

collected in the POTW residuals stream, then the need for any special storage, handling, 

management, or disposal controls should be assessed. The EPA retrospective studies need to 

investigate this issue. In states that allow land application of POTW residuals, there is a large 

data set on sludge quality and chemistry. The prospective studies might be designed to assess 

the ability to predict treatment performance, and then predict the real time genesis of outflow and 

residuals composition from the POTWs.

The draft Study Plan should address the cumulative consequences of carrying out multiple HF 

operations in a single watershed or region. Examples of such consequences include causing a 

water body to exceed its total maximum daily load limit, which may cause the waterbody to be 

considered impaired and placed on the “303(d) list” of impaired waters (stream segments, lakes) 

that the Clean Water Act requires all states to submit for EPA approval. The SAB notes that an 

important impact of the cumulative HF wastewater discharges in a region might be missed if the 

focus is entirely on discharges from individual developments. This is especially true given the 
55

fact that entire regions are now under development or consideration for development of these 

hydrocarbon resources. Some example study questions include: “What is the assimilative 

capacity of natural systems (wetlands, lakes, streams) to accommodate hydraulic fracturing 

treated wastewaters?”; “Is this the best expenditure of ecosystem services?”; and “Is this an 

equitable expenditure of environmental services?”

The DOE collaboration associated with treatment technologies should be more clearly articulated 

and defined, as well as the anticipated collaboration with any other entities mentioned in the draft 

Study Plan.
56

Research Outcomes

Charge Question 5: If EPA conducts the proposed research, will we be able to:

a. Identify the key impacts, if any, of hydraulic fracturing on drinking water 

resources; and 

b. Provide relevant information on the toxicity and possible exposure pathways of 

chemicals associated with hydraulic fracturing?

3.9.1. General Comments

EPA has proposed to conduct certain research activities associated with all stages of the 

hydraulic fracturing water lifecycle shown in Figure 7 of the Study Plan in order to address the 

research questions posed in Table 2 and summarized in Figure 9 of the Study Plan. Table 2 and 

Figures 7 and 9 are provided within this report as Appendix B, Appendix C, and Appendix D, 

respectively. EPA proposes to conduct the research using case studies and generalized scenario 

evaluations, which will rely on data produced by a combination of the tools listed in Section 5.3 

of the Study Plan. In addition, EPA outlines a program of quality assurance that will be 

developed for all aspects of the proposed research. EPA’s proposed research activities for each 

stage of the hydraulic fracturing water lifecycle are outlined in Figure 9 of the Study Plan, and 

EPA provides brief summaries of how the proposed research activities will answer the 

fundamental research questions. 

To respond to this Charge Question, the SAB focused on the potential research outcomes that 

EPA identified for each step in the HF water lifecycle. These potential research outcomes are 

identified in Chapter 6 of the draft Study Plan, at the end of the discussion of each stage of the 

water lifecycle. For each potential research outcome listed in the draft report, the SAB 

determined whether the outcome is likely to be achieved in whole, in part, or not at all, by the 

proposed research. 

The two charge sub-questions are inherently very broad, primarily because of the heterogeneity 

of hydraulic fracturing operations. For example, the potential ‘key impacts’ of hydraulic 

fracturing are likely to depend strongly on local geological and hydrological conditions, and the 

magnitude of those impacts is likely to depend on the site-specific details of the fracturing 

operation and the management practices that are in place, both for routine operation and for 

dealing with emergency situations such as flooding and spills. For this reason, the short (but not 

particularly helpful) response to the charge question is: “Yes” at some sites and under certain 

conditions, and “No” at other sites or under other conditions. While one could try to identify the 

most important conditional factors that influence the potential impacts of HF at different sites 

and then prepare a response to the charge question for each of the corresponding contingencies, 

the SAB concludes that such an approach would lead to a large and unwieldy matrix of 

conditional contingencies that would not be particularly valuable to EPA or the stakeholders.

In responding to these two charge sub-questions, the SAB reiterates the importance of assessing 

uncertainty at each step in the research study. Given time and resource constraints, the studies 

will not be able to answer all questions with a high degree of certainty. The SAB recommends 

that EPA explicitly identify or estimate the uncertainty or confidence in all research conclusions, 

and in the assessment of cause and effect associated with potential HF impacts to drinking water 
57

supplies. The quality of the information on which the research was based as well as any 

uncertainties arising in the conduct of the research should be evaluated, at least in a preliminary 

manner.

The SAB focused on the potential research outcomes that the EPA identified for each step in the 

HF water lifecycle. These potential research outcomes are identified in Chapter 6 of the draft 

Study Plan, at the end of the discussion of each stage of the water lifecycle. For each potential 

research outcome listed in the draft report, the SAB attempted to determine whether the outcome 

is likely to be achieved in whole, in part, or not at all, by the proposed research. The SAB 

recognizes that the ability to achieve a particular potential outcome is contingent on local 

conditions and therefore cannot be assessed for all sites in a limited research program. 

Nevertheless, the potential research outcomes are much more specific than the charge question 

and the SAB finds this specificity allows for more focused evaluation.

The SAB recognizes that the EPA did not claim that the listed potential research outcomes were 

comprehensive, or that the lists comprised the most important outcomes that the research would 

achieve. However, the potential research outcomes appeared as the final entry in the sections 

describing the various steps in the HF water life cycle, and the SAB concludes that EPA intended 

the lists to capture most of the key outcomes that EPA hoped would be achieved. The SAB 

considered whether other, non-listed research outcomes might affect SAB’s response to the 

charge question, but did not identify any non-listed outcomes that would significantly alter this 

SAB assessment. 

As described further below, the SAB concludes that: 1) all of the potential water acquisition 

research outcomes identified by EPA can be achieved; 2) approximately 50% of the potential 

chemical mixing research outcomes identified by EPA can be achieved; 3) approximately 40% 

of the potential well injection research outcomes identified by EPA can be achieved; 4) 

approximately 40% of the potential 

flowback and produced water research outcomes identified by EPA can be achieved; and 5) 

approximately 33% of the potential wastewater treatment and waste disposal research outcomes 

identified by EPA can be achieved. 

The SAB concludes that all of the potential water acquisition research outcomes identified by 

EPA can be achieved. EPA can identify possible impacts on water availability and quality 

associated with large-volume water withdrawals for hydraulic fracturing. Also, EPA could 

determine the cumulative effects of large volume water withdrawals within a watershed and 

aquifer, and develop metrics that can be used to evaluate the vulnerability of water resources. 

While the SAB agrees that these research outcomes can be accomplished at HF sites that are 

carefully characterized in the case studies, the potential for extrapolation of these findings to 

other sites will be limited. Regarding the assessment of current water resource management 

practices related to hydraulic fracturing, the SAB concludes that EPA can accomplish this task 

through collection of data on water management practices from a representative cross-section of 

the industry. However, it is unclear whether the “assessment” referred to in this outcome would 

comprise only data-gathering about existing `management practices or a more in-depth analysis 

of the effectiveness of the practices. 
58

With respect to the chemical mixing life-cycle stage, the SAB concludes that EPA can 

summarize available data on the identity and frequency of use of many (but not all) hydraulic 

fracturing chemicals, the concentrations at which the chemicals are typically injected, and the 

total amounts used, assuming cooperation from the HF service companies is forthcoming. The 

goal of identifying the toxicity of chemical additives can be achieved for those additives whose 

toxicity has been studied previously, and the goal of identifying data gaps can also be achieved. 

The SAB finds that the outcome of identifying chemical indicators for HF fluids is a worthy 

goal, but is skeptical that this outcome can be achieved. The SAB concludes that the outcome of 

determining the likelihood that surface spills will result in the contamination of drinking water 

resources is too broad to achieve in a general sense, but that it will be possible to achieve that 

outcome for a few chemicals that can be selected based on their potential to pose significant risk 

to human and environmental health. The SAB agrees that an assessment of management 

practices related to on-site chemical storage and mixing is achievable as part of the proposed 

research, assuming full cooperation of the HF service companies.

With respect to the well injection life-cycle stage, the frequency and severity of well failures, as 

well as the factors that contribute to them, can be assessed, if the relevant data are supplied by 

the HF service companies and if EPA determines the number of hydraulically fractured wells in 

a defined period for which well failure data are also available. The goal of identifying the key 

conditions that determine the extent of interaction of existing pathways with hydraulic fractures 

is excessively broad and is unlikely to be achieved in a way that is of significant practical value. 

However, significant progress toward achieving this goal might be made in cases where 

appropriate modeling has been carried out by the HF service companies, if those companies 

make their data available to the EPA. The SAB concludes that while EPA could identify the key 

conditions that increase or decrease the likelihood of the interaction of existing pathways with 

hydraulic fractures through modeling, the simulated outcomes will be dependent on assumptions 

and choices made about how to represent the physical system. These assumptions and choices 

may not be well constrained by reliable data. The outcome of analyzing water quality of a 

potentially affected water body before, during, and after injection can certainly be achieved. 

However, implicit in this outcome is the expectation that any impacts of HF activities could be 

inferred based on changes in water quality. The SAB is skeptical that such impacts could be 

detected in the relatively short time frame of the proposed research. While the SAB agrees that 

EPA can evaluate water quality before, during, and after injection, the evaluation might have to 

be continued substantially beyond the end of the initial research before the outcome can be 

established with reasonable confidence. The goal of quantifying the mobility and fate of HF 

additives and of naturally occurring substances that are mobilized by HF activities (e.g., 

formation fluid, gases, trace elements, radionuclides, organic material), and other substances that 

might be mobilized or rendered more toxic by the introduction of the fracturing fluid, is too 

broad to be achieved by the proposed research, but this goal might be achieved for a limited 

number of high-priority chemicals. Specific comments on analytical methods are included 

within this Report’s response to Charge Question 2. 

With respect to the flowback and produced water (i.e., post-fracturing produced water), the SAB 

concludes that the outcomes of compiling existing data on the identity, quantity, and toxicity of 

flowback and produced water, and the preparation of a prioritized list of components for future 

investigation with respect to toxicity and human health effects are achievable. EPA plans to 
59

determine the likelihood that surface spills will result in the contamination of drinking water 

resources. The outcome of determining the likelihood that surface spills will result in the 

contamination of drinking water resources is too broad to be achievable in any meaningful way. 

The SAB finds that this likelihood will be highly site specific and will not be quantifiable with a 

simple, generalized equation, and thus the SAB does not agree that the outcome can be achieved 

or quantified by some generalized equation. However, procedures can be developed for 

assessing the likelihood that surface spills will lead to significant contamination of drinking 

water, when the procedures are applied to specific spill scenarios in specific hydrogeologic 

settings. The description of the data that will be collected in order to evaluate the risks to 

drinking water resources posed by current methods for on-site management of HF wastes is 

vague. A thorough analysis of on-site management practices could be useful for evaluating those 

risks, but the SAB is unable to assess whether the data that will be collected and the analysis that 

will be conducted will achieve that goal.

With respect to wastewater treatment and waste disposal, the SAB concludes that the research 

will achieve the outcome of identifying the fate and effects of inorganic constituent of HF wastes 

in 

wastewater treatment and drinking water treatment plants with minimal or no new laboratory 

research (largely, but not exclusively, by literature surveys and information generated in an 

ongoing DOE study; see U.S. Department of Energy, 2011). This goal is unlikely to be achieved 

for organic constituents of HF wastes, especially those that will be present in trace 

concentrations after mixing with other water entering the treatment plants. The SAB agrees that 

EPA may be able to achieve an outcome of assessing some short- and long-term effects of the 

constituents resulting from inadequate treatment of hydraulic fracturing wastewaters on water 

and wastewater treatment processes, and on the water quality of the treated water. However, this 

potential outcome can be achieved only for a very limited range of potential effects.

In addition to the research outcomes identified in the draft research plan, the SAB recommends 

that EPA include as an outcome the generation of new research ideas for reducing the potential 

adverse effects of HF activities (for example, ways to reduce water usage, identify BMPs, or 

develop ‘greener’ HF additives).

An additional issue is that EPA needs to view the environmental concerns and issues in the 

context of the local community. Specific comments on environmental justice issues are included 

within this Report’s response to Charge Question 2. 

3.9.2. Specific Comments

Potential Research Outcomes: Water Acquisition (Section 6.1)

The potential research outcomes related to water acquisition identified in the draft Study Plan 

were:

a) Identify possible impacts on water availability and quality associated with large volume water 

withdrawals for hydraulic fracturing.
60

b) Determine the cumulative effects of large volume water withdrawals within a watershed and 

aquifer.

c) Develop metrics that can be used to evaluate the vulnerability of water resources. 

d) Provide an assessment of current water resource management practices related to hydraulic 

fracturing.

SAB's response to these outcomes is as follows:

a) The SAB considers Outcome 6.1a to be largely a conceptual outcome that can be achieved by 

understanding the steps involved in hydraulic fracturing and the environment in which it is 

conducted. The phrase “possible impacts” suggests that the task can be accomplished by 

brainstorming among a broad and representative group of technical experts and stakeholders. A 

significant amount of such brainstorming has already occurred, and most of the possible impacts 

of HF have probably been identified. Continued attention should be paid to this task throughout 

the project to increase the chance of identifying other, less obvious potential impacts, based on 

data collected and observations made as the research progresses. Thus, the SAB agrees that 

Outcome 6.1a can be achieved.

b, c) The possible cumulative effects of large volume withdrawals from a watershed have been 

documented in many prior water resource investigations unrelated to HF (see U.S. Army 

Engineer Waterways Experiment Station, 1999; Prudic, D.E., 2007; and Alberta Environment, 

2007). These effects are highly site-specific, and many studies on withdrawal do not address 

impacts on water quality. Most large withdrawals are tied to either high density areas or 

agriculture, and HF activities can be within low density non-agricultural areas. The outcome of 

determining the cumulative effects of large volume water withdrawals will be accomplished at 

HF sites that are carefully characterized in case studies, and the potential for extrapolation of the 

findings to other sites will be limited due to the unique site-specific ecological and 

developmental factors associated with the locations for each case study.

The situation is largely the same with respect to establishment of metrics for evaluating the 

vulnerability of water resources to withdrawal of large volumes of water. It might be possible to 

establish metrics that relate specifically to HF environments and activities, such as the presence 

of pre-existing hydraulic interconnections in the underground (e.g., from mines) or the 

generation of such pathways during the HF process. However, while these metrics might be 

categorized as generally applicable, the data needed to apply them are detailed and site-specific, 

so it is unclear whether simply identifying the metrics represents a valuable outcome.

d) It is unclear to the SAB whether the “assessment” referred to in this outcome would comprise 

only data-gathering about existing management practices or a more in-depth analysis of the 

effectiveness of the practices. If the former, then the task can be accomplished by collection of 

data on water management practices from a representative cross-section of the industry. If the 

latter, then the metrics for evaluating the practices need to be carefully developed, and it is not 

clear that the EPA has paid sufficient attention to this effort to allow it to succeed.
61

Potential Research Outcomes: Chemical Mixing (Section 6.2) 

The potential research outcomes related to chemical mixing identified in the draft Study Plan 

were:

a) Summarize available data on the identity and frequency of use of various hydraulic fracturing 

chemicals, the concentrations at which the chemicals are typically injected, and the total amounts 

used.

b) Identify the toxicity of chemical additives, and apply tools to prioritize data gaps and identify 

chemicals for further assessment. 

c) Identify a set of chemical indicators associated with hydraulic fracturing fluids and associated 

analytical methods.

d) Determine the likelihood that surface spills will result in the contamination of drinking water 

resources.

e) Assess current management practices related to on-site chemical storage and mixing.

SAB's response to these outcomes is as follows:

a) SAB concludes that Potential Outcome 6.2a is achievable, assuming cooperation from the HF 

service companies is forthcoming. The Panel noted that a state agency in Wyoming is currently 

collecting data on chemical use in HF, and the EPA should take maximum advantage of that 

effort, as well as any similar efforts undertaken by other state, federal, or non-governmental 

agencies.

b) The SAB does not agree that it is possible, within the cost and time constraints of the 

proposed research, to collect and evaluate new data on human toxicity of HF chemical additives. 

Specific comments on hazard identification, exposure assessment, toxicity testing, analytical 

methods, and indicators of contamination are included within this Report’s response to Charge 

Question 2. 

c) The logical potential chemical indicators of HF fluids are the HF additives themselves and, in 

some cases, specific salt ions or aggregate measures of salt concentration (e.g., specific 

conductivity, TDS). The HF additives are usually added at low concentrations into the injected 

water, and they are likely to be partially modified (e.g., by microbial action), volatilized, and/or 

diluted substantially before entering a drinking water resource. Development of analytical 

methods for detecting low concentrations of such chemicals can be very time-consuming and 

costly. On the other hand, in situations where the concentration of salts (or the relative 

concentration of specific ions) can serve as an indicator of HF fluids, no research is needed to 

choose the specific indicator (either chloride or TDS is likely to be as good as any other choice), 

and no methods development is required. Therefore, the SAB recommends that during this 

project, inorganic salts and, possibly, organic HF additives for which analytical methods already 

exist be used as chemical indicators of the presence of HF fluids in water resources. If it is 
62

determined, based on other components of the research, that some HF chemicals might be 

particularly valuable indicators of the presence of HF fluids, then efforts to develop analytical 

methods for those chemicals can be undertaken subsequently.

It should be noted that, if a chemical that is present in the formation water (e.g., chloride) is 

chosen as the indicator and is found at elevated concentrations in a nearby water resource, the 

possibility can be raised that the concentration increase would have occurred even in the absence 

of HF activity. Barring the unlikely possibility that a direct pathway for the chemical from the 

HF environs to the water resource can be established, this issue falls more in the legal than the 

scientific domain (i.e., what is the burden of proof needed to attribute the higher concentration to 

HF activity?). In addition, establishing that an increase in concentration has occurred at a site 

where HF activity has been ongoing for several years would require some historical record of the 

concentration of the indicator prior to HF activity; at a site where HF activity is starting (i.e., the 

site of a prospective case study), it would require that the indicator appear in the water resource 

within one or at most two years for the potential outcome to be achieved during this research 

program. Neither of these scenarios can be assured, even if an appropriate indicator is selected. 

Use of HF additives as indicators does not suffer from this drawback but, as noted above, it is 

likely to be considerably more difficult to detect such additives in the water resource. For these 

reasons, although the SAB is supportive of the search for an indicator chemical as part of this 

project, it is not convinced that an appropriate indicator will be found (i.e., this outcome is a 

worthy goal, but it might not be achieved).

d) There is no question that surface spills of HF fluids are potential sources of contamination to 

shallow aquifers or surface waters. The likelihood that such contamination will actually occur 

depends strongly on the management practices for the HF liquid waste stream and on the local 

geology and hydrology, as well as the magnitude of the spill and the types of retardation and/or 

transformations to which the chemicals are susceptible. Useful information on the possible 

modes of transport and transformation of HF chemicals can be obtained in laboratory studies, but 

such studies also depend on the hydrogeological conditions and are often costly to conduct. The 

SAB finds that a general question about “the likelihood that surface spills will result in the 

contamination of drinking water resources” is unanswerable, but that it can be answered once 

site-specific and contaminant-specific information is available. Because of the cost of obtaining 

the necessary contaminant-specific information, it is appropriate for the EPA to identify the 

chemicals that pose the greatest risk to human and environmental health before initiating such 

studies. To the extent that those chemicals can be identified, and their transport and 

transformation characterized, as part of this research program, the outcome can be achieved for 

those chemicals. If these tasks cannot be completed as part of the current research program, then 

the research will still generate a useful outcome, but the goal of determining the likelihood of 

contamination of drinking water resources will not be achieved.

e) Assuming that HF service companies are forthcoming with information about their chemical 

storage and mixing management practices, and that a broad data-gathering effort is undertaken, 

an assessment of management practices related to on-site chemical storage and mixing is 

achievable as part of the proposed research. It should be noted that chemical storage and mixing 

in HF are not obviously and fundamentally different from the corresponding activities in many 

other industrial settings. The implicit question that is being addressed by this potential outcome 
63

is whether the management practices are appropriate for the risks and challenges that exist for 

chemical storage and mixing at HF sites. Data regarding current practices, when combined with 

an assessment of the risks associated with chemical storage and mixing, should help answer this 

question.

Potential Research Outcomes: Well Injection (Section 6.3)

The potential research outcomes related to well injection identified in the draft Study Plan were:

a) Determine the frequency and severity of well failures, as well as the factors that contribute to 

them.

b) Identify the key conditions that increase or decrease the likelihood of the interaction of 

existing pathways with hydraulic fractures.

c) Evaluate water quality before, during, and after injection.

d) Determine the identity, mobility, and fate of potential contaminants, including fracturing fluid 

additives and/or naturally occurring substances (e.g., formation fluid, gases, trace elements, 

radionuclides, organic material) and their toxic effects.

e) Develop analytical methods for detecting chemicals associated with hydraulic fracturing 

events.

SAB's response to these outcomes is as follows:

a) Outcome 6.3a is achievable if thorough historical data on well failures are provided by the HF 

service companies and if EPA determines the number of hydraulically fractured wells in the 

country. The draft Study Plan indicates that “EPA will select a representative sample of sites 

and request the complete well files for the sites” and “will analyze the well files to assess the 

typical causes, frequency, and severity of well failures.” From these statements, it is clear that 

EPA anticipates full cooperation from service companies. If that cooperation is forthcoming, 

then this task will be achievable and could yield valuable information.

b) EPA proposes to achieve potential Outcome 6.3b primarily or exclusively via computer 

modeling of contaminant transport under various “hydraulic fracturing well injection scenarios,” 

taking into account features of both the engineering systems and the local geology. Such 

modeling will undoubtedly shed some light on the potential contamination of drinking water

sources during the well injection phase of HF operations. However, the simulated outcomes will 

be strongly dependent on assumptions and choices made about how to represent the physical 

system, and the SAB has concerns that these assumptions and choices are not well constrained 

by reliable data. As a result, converting the modeling outcomes to useful interpretive or 

predictive outcomes may be problematic if the modeling assumptions and choices are not well 

constrained by reliable data. The SAB is unable to determine if sufficient data exist to constrain 

modeling choices, and thus cannot determine if this outcome can be met.
64

As currently phrased, the claimed potential outcome is excessively broad and is unlikely to be 

achieved in a way that is of significant practical value. For example, the presence of many preexisting interconnected fractures is likely to facilitate interaction of existing pathways with 

hydraulic fractures, but that conclusion is intuitive. Modeling could probably be carried out to 

identify some details of pre-existing fractures that pose especially high risk for interaction with 

hydraulic fractures. The effort required for such modeling is large, but in many cases much of 

the modeling might already have been completed as part of the pre-drilling analysis. EPA should 

request any geophysical data, well logs, etc., that the developers of sites have accumulated and 

use that information to the extent possible in this portion of the research

c) The SAB assumes that the water quality referred to in potential Outcome 6.3c was the water 

quality of the drinking water source that might be at risk of contamination as a result of HF 

activities. The plan to evaluate water quality before, during, and after injection of the HF fluids 

indicates that this potential outcome applies primarily or exclusively to the prospective case 

studies. While there is no doubt that such an evaluation can be carried out, the water quality 

parameters that are analyzed will probably undergo minimal change during the relatively short 

duration of the research program. In addition, the need to rely on inorganic salts as tracers for 

the HF fluids (because analytical methods for the organic additives are either not available at all, 

or not yet proven for the concentrations and matrices of interest) will complicate the 

interpretation of the data, because it will raise the question of whether hydraulic fracturing was 

truly the cause of any observed change in chemical composition.

The SAB has some concern that the absence of a strong contaminant signal could be 

misinterpreted as support for the null hypothesis (i.e., that the contaminants cannot migrate to the 

water body), when in fact it simply reflects a time lag between the initiation of HF activities and 

the appearance of HF fluids in the water source that is longer than the observation period. The 

SAB concludes that the water quality evaluation that will be carried out is a worthwhile effort, 

but that it might have to be continued substantially beyond the end of the initial research before 

the outcome can be established with reasonable confidence.

d) Potential Outcome 6.3d is written in a way that suggests that the identity, mobility, fate, and 

toxicity of all potentially significant contaminants will be determined as part of the project, and 

that outcome is clearly not achievable. As noted elsewhere in this report, the SAB recommends 

that none of the proposed toxicity testing be carried out as part of the current research. If that 

recommendation is accepted, the determination of toxic effects will be limited to those 

contaminants for which the toxicity has already been assessed. However, the goal of quantifying 

the mobility and fate of the contaminants that are deemed to be of highest priority is achievable. 

Given the plethora of HF additives and naturally occurring substances of potential interest, the 

SAB recommends that the contaminants of primary concern be identified based on an initial 

investigation of their usage rates, physical/chemical properties, and potential routes of human 

exposure, and that transport-and-fate studies be carried out only on those contaminants, by a 

combination of laboratory, field, and computer modeling experiments.

e) Specific comments on hazard identification, exposure assessment, toxicity testing, analytical 

methods, and indicators of contamination are included within this Report’s response to Charge 

Question 2. 
65

Potential Research Outcomes: Flowback and Produced Water (Section 6.4)

The potential research outcomes related to flowback and produced water identified in the draft 

Study Plan were:

a) Compile information on the identity, quantity, and toxicity of flowback and produced water 

components.

b) Develop analytical methods to identify and quantify flowback and produced water 

components.

c) Provide a prioritized list of components requiring future studies relating to toxicity and human 

health effects.

d) Determine the likelihood that surface spills will result in the contamination of drinking water 

resources.

e) Evaluate risks posed to drinking water resources by current methods for on-site management 

of wastes produced by hydraulic fracturing.

SAB's response to these outcomes is as follows: 

a) The compilation of existing data relating to the identity, quantity, and toxicity of flowback and 

produced water components is achievable as part of the research, and the SAB finds that 

successful completion of this step is critical. The SAB wishes to reiterate its belief that the 

toxicity data collected as part of this effort should be restricted to data that are already in the 

scientific literature.

b) Specific comments on hazard identification, exposure assessment, toxicity testing, analytical 

methods, and indicators of contamination are included within this Report’s response to Charge 

Question 2. 

c) The likelihood that surface spills will result in contamination of drinking water resources 

depends on the volume of the spill, the identities and concentrations of the contaminants in the 

spillage, and the details of the potential pathways from the site of the spill to the water resource. 

Therefore, this likelihood is highly site specific and cannot be quantified by some generalized 

equation. The SAB agrees that the EPA understands and appreciates this site-specificity, but the 

wording of potential outcome 6.4d does not reflect that understanding; therefore, if the potential 

outcome is interpreted literally, it cannot be achieved. The SAB recommends that EPA consider 

revising this potential outcome so that it refers to development of procedures that can be used to 

assess the likelihood that various types of surface spills will lead to significant contamination of 

drinking water resources, when the procedures are applied to specific spill scenarios in specific 

hydrogeologic settings.
66

d) The data that the EPA anticipates collecting with regard to on-site management of HF wastes 

are vague. The draft plan indicates the data will be collected from literature reviews, 

retrospective case studies, and prospective case studies, but it is unclear exactly what information 

will be sought. Statements such as, “it will be informative to compare the typical management 

practices to unexpected situations that may lead to impacts...on drinking water resources” and 

“information will also be collected on the ways in which wastewater is transported for treatment 

or disposal” suggest that the research will, at best, generate a list of some management (and 

probably some mismanagement) practices. However, it is difficult to see how such data will be 

translated into a useful, generalized evaluation of the risks associated with on-site management 

of HF wastes.

Potential Research Outcomes: Wastewater Treatment and Waste Disposal (Section 6.5)

The potential research outcomes related to wastewater treatment and waste disposal identified in 

the draft Study Plan were:

a) Evaluate treatment and disposal methods that are currently being used to treat flowback and 

produced water resulting from hydraulic fracturing activities.

b) Assess the short- and long-term effects resulting from inadequate treatment of hydraulic 

fracturing wastewaters.

SAB's response to these outcomes is as follows: 

a) The SAB interpreted potential outcome 6.5a as comprising both the effectiveness with which 

components of HF wastes can be removed from the waste stream using treatment and disposal 

methods that are currently being used to treat HF wastewater, and the effect of such wastes on 

the performance of treatment processes with respect to removal and/or degradation of other (nonHF) waste components. It should be noted that, in some cases, the HF wastes might be reused by 

injection into new wells, and the changes in water quality associated with such reinjection should 

be considered when assessing the composition of the wastes needing treatment. The draft Study 

Plan identifies pre-treatment of HF wastewaters prior to direct land application or prior to 

discharge to a community wastewater treatment system, as well as discharge directly to a 

community wastewater treatment system (without pre-treatment) as potential treatment/disposal 

methods. The draft Study Plan notes that substantial work that addresses these issues has been 

completed by DOE NETL, and that only research to fill in the remaining knowledge gaps will be 

carried out as part of the proposed project. It is not clear that an assessment of the effectiveness 

of pre-treatment for solutions that will be re-injected is an important research activity for this 

project.

The monovalent inorganic constituents in HF wastes can be removed from the solution only by 

desalination processes such as reverse osmosis, and the effectiveness of these processes is 

relatively well-established. Some of the organic constituents of HF wastes might be removed by 

biodegradation, volatilization, or adsorption, but few studies have attempted to track these 

compounds as they pass through a treatment plant, and the feasibility of doing so in situations 
67

where the HF fluids are discharged to a POTW is complicated by the low concentrations of those 

compounds that are expected to be present once the HF fluids have been diluted by other 

influents to the plant.

The effects of the major inorganic contaminants in HF waste fluids on wastewater treatment 

processes and on soils have been extensively studied in other contexts, and the results of that 

research should be taken into account, along with the results of the DOE research. The effects of 

the organic contaminants on process performance will be more difficult to evaluate, other than 

anecdotally, for the same reasons that make the fate of the compounds themselves difficult to 

assess.

Based on the above considerations, the SAB concludes that potential outcome 6.5a is likely 

achievable with respect to the inorganic constituents of HF wastes, with minimal or no new 

laboratory research. However, the same cannot be said for the organic constituents. For the 

organic constituents, it is unlikely that this potential outcome will be achieved in situations 

where the HF wastes are a small portion of the total waste stream entering the treatment plant. 

The outcome might be achieved in a scenario where the HF wastes account for the majority of 

the influent to the treatment process (e.g., in a treatment or pre-treatment facility treating only 

HF fluid or wastewater consisting primarily of HF fluid).

b) Taken in conjunction with the research plan for topic 6.5, it appears that potential outcome 

6.5b is referring primarily to the effects that components of HF wastewaters might have on 

drinking water quality (e.g., TDS in drinking water, DBP formation during disinfection of 

drinking water) and the infrastructure of wastewater and drinking water treatment systems (e.g., 

increasing corrosion rates). Although the potential outcome is written as though a wide (or even 

comprehensive) range of such effects will be investigated, in truth only a couple will be 

explored. Furthermore, even those effects are probably better studied by combining mass 

balance calculations with existing literature on DBP formation and corrosion. The SAB's 

assessment is that this potential outcome can be achieved for a very limited range of effects, and 

that very little new laboratory research is required to do so.
A-1

APPENDIX A: EPA’s CHARGE TO THE PANEL

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

Office of Research and Development

February 9, 2011 

MEMORANDUM

SUBJECT: Request for review of the Draft Plan to Study the Potential Impacts of Hydraulic 

Fracturing on Drinking Water Resources 

FROM: Fred S. Hauchman, Director /Signed/

Office of Science Policy (8104R)

TO: Edward Hanlon, Designated Federal Officer

EPA Science Advisory Board Staff (1400R)

This memorandum requests that the Science Advisory Board (SAB) review and comment 

on the EPA Office of Research and Development’s (ORD) Draft Plan to Study the Potential 

Impacts of Hydraulic Fracturing on Drinking Water Resources. The purpose of this draft study 

plan is to identify research activities that will answer the following questions:

• Can hydraulic fracturing impact drinking water resources?

• If so, what are the conditions associated with the potential impacts on drinking water resources? 

Background

Hydraulic fracturing, which involves the pressurized injection of water, chemical 

additives, and proppants into geological formations, induces fractures in the formation that 

stimulate the flow of natural gas or oil, thus increasing the volume of gas or oil that can be 

recovered from coalbeds, shales, and tight sands. As natural gas production has increased, so 

have concerns about the potential environmental and human health impacts of hydraulic 

fracturing in the U.S., particularly with respect to drinking water resources. In its Fiscal Year 

2010 Appropriation Conference Committee Directive to EPA, the U.S. House of Representatives 

urged EPA to conduct a study of hydraulic fracturing and its relationship to drinking water, 

specifically:

“The conferees urge the Agency to carry out a study on the relationship between 

hydraulic fracturing and drinking water, using a credible approach that relies on the 

best available science, as well as independent sources of information. The conferees 

expect the study to be conducted through a transparent, peer-reviewed process that 

will ensure the validity and accuracy of the data. The Agency shall consult with other 

Federal agencies as well as appropriate State and interstate regulatory agencies in 

carrying out the study, which should be prepared in accordance with the Agency's 

quality assurance principles.”
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In March 2010, EPA asked the SAB to review an initial research scoping document 

related to hydraulic fracturing.1 This document outlined the initial approach for determining the 

scope of the study, potential research questions, and an initial approach for conducting the study. 

In its response to EPA2

We appreciate the efforts of the SAB to prepare for the upcoming review of the Draft 

Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources, and 

we look forward to discussing the plan in detail on March 7-8, 2011. Questions regarding the 

enclosed materials should be directed to Susan Burden at 

in June 2010, the SAB endorsed a lifecycle approach for the study plan, 

and recommends that: (1) initial research be focused on potential impacts to drinking water 

resources, with later research investigating more general impacts on water resources; (2) five to 

ten in-depth case studies be conducted at “locations selected to represent the full range of 

regional variability of hydraulic fracturing across the nation”; and (3) engagement with 

stakeholders occur throughout the research process.

Following the receipt of the SAB comments in June 2010, EPA developed the attached 

Draft Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. 

The draft plan focuses on the full lifecycle of water in the hydraulic fracturing process, from 

water acquisition, through the mixing of chemicals and actual fracturing, to the post-fracturing 

stage, including the management of flowback and produced water and its ultimate treatment 

and/or disposal. The research questions outlined in the study plan address how activities in each 

of these stages may impact drinking water resources. EPA has identified these research 

questions from stakeholder meetings and a review of the existing literature on hydraulic 

fracturing. Stakeholders have also helped EPA to identify the potential case study sites 

discussed in the draft study plan. 

Specific Request

ORD requests that the SAB comment on the scope, proposed research questions, research 

approach, research activities, and research outcomes outlined in the Draft Plan to Study the 

Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. Comments from the 

SAB will be considered during the development of the final plan to study the potential impacts of 

hydraulic fracturing on drinking water resources. 

burden.susan@epa.gov or 202-564-

6308.

 1

http://yosemite.epa.gov/sab/sabproduct.nsf/0/3B745430D624ED3B852576D400514B76/$File/Hydraulic%20Frac

%20Scoping%20Doc%20for%20SAB-3-22-10%20Final.pdf

2

http://yosemite.epa.gov/sab/sabproduct.nsf/0/CC09DE2B8B4755718525774D0044F929/$File/EPA-SAB-10-009-

unsigned.pdf
A-3

Charge to the SAB 

We ask the SAB to focus on the questions below during the review of the Draft Plan to 

Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources:

1. Water Use in Hydraulic Fracturing

EPA has used the water lifecycle shown in Figure 7 to characterize hydraulic fracturing 

and to identify the potential drinking water issues. Please comment on the 

appropriateness of this framework for the study plan. Within the context of the water 

lifecycle, does the study plan adequately identify and address the areas of concern?

2. Research Questions

EPA has identified both fundamental and secondary research questions in Table 2. Has 

EPA identified the correct research questions to address whether or not hydraulic 

fracturing impacts drinking water resources, and if so, what those potential impacts may 

be?

3. Research Approach

The approach for the proposed research is briefly described in Chapter 5. Please provide 

any recommendations for conducting the research outlined in this study plan, particularly 

with respect to the case studies. Have the necessary tools (i.e., existing data analysis, 

field monitoring, laboratory experiments, and modeling) been identified? Please 

comment on any additional key literature that should be included to ensure a 

comprehensive understanding of the trends in the hydraulic fracturing process.

4. Proposed Research Activities

Proposed research activities are provided for each stage of the water lifecycle and 

summarized in Figure 9. Will the proposed research activities adequately answer the 

secondary questions listed in Table 2 for each stage of the water lifecycle? Please 

provide any suggestions for additional research activities.

5. Research Outcomes

If EPA conducts the proposed research, will we be able to:

a. Identify the key impacts, if any, of hydraulic fracturing on drinking water resources; and 

b. Provide relevant information on the toxicity and possible exposure pathways of 

chemicals associated with hydraulic fracturing?

Attachment: Draft Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking 

Water Resources
B-1

APPENDIX B: Table 2 From EPA’s February 2011 Draft Hydraulic 

Fracturing Study Plan
B-2
C-1

APPENDIX C: Figure 7 From EPA’s February 2011 Draft Hydraulic 

Fracturing Study Plan
C-2
D-1

APPENDIX D: Figures 9a and 9b From EPA’s February 2011 Draft 

Hydraulic Fracturing Study Plan
D-2
D-3