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\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
| 1 WASHINGTON D.C. 20460
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OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
August 11, 2016
EPA-SAB-16-005
The Honorable Gina McCarthy
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
Subject: SAB Review of the EPA's draft Assessment of the Potential Impacts of Hydraulic
Fracturing for Oil and Gas on Drinking Water Resources
Dear Administrator McCarthy:
The EPA Science Advisory Board (SAB) is pleased to transmit its response to a request from the U.S.
Environmental Protection Agency (EPA) Office of Research and Development (ORD) to review and
provide advice on scientific charge questions associated with the EPA's draft Assessment of the
Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources (External
Review Draft, EPA/600/R-15/047, June 2015). The draft Assessment Report synthesizes available
scientific literature and data on the potential impacts of hydraulic fracturing for oil and gas development
on drinking water resources, and identifies possible operational events during the life cycle of hydraulic
fracturing for oil and gas operations that could result in impacts to drinking water.
The SAB was asked to comment on the EPA's statements on the goals, background and history of its
Assessment; on the EPA's analyses regarding the water acquisition, chemical mixing, well injection,
flowback and produced water, and wastewater treatment and waste disposal steps of the hydraulic
fracturing water cycle (HFWC); on the EPA's analysis of chemicals used or present in hydraulic
fracturing fluids; and on the EPA's synthesis of science on potential impacts of hydraulic fracturing on
drinking water resources as presented in the Assessment's Chapter 10 and Executive Summary. The
specific charge questions to the SAB Hydraulic Fracturing Research Advisory Panel (SAB Panel) from
the EPA are provided as Appendix A to the SAB report.
The EPA developed the draft Assessment Report in response to a request in 2009 from the U.S.
Congress, which urged the EPA to examine the relationship between hydraulic fracturing and drinking
water resources. The EPA consulted with stakeholders, and developed a Research Scoping document
followed by a detailed research Study Plan, both of which were reviewed by the SAB, in 2010 and in
2011, respectively. An EPA Progress Report on the study detailing the research approaches, activities,
and remaining work was released in late 2012. A consultation on the Progress Report was conducted in
May 2013 with members of the SAB Panel. The EPA's draft Assessment Report was released in June
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2015 for public comment and review by the SAB Panel operating under the auspices of the chartered
SAB.
In general, the SAB finds the EPA's overall approach to assess the potential impacts of HFWC
processes for oil and gas production on drinking water resources, focusing on the individual stages in the
HFWC, to be comprehensive but lacking in several critical areas. The SAB also finds that the agency
provided a generally comprehensive overview of the available literature that describes the factors
affecting the relationship of hydraulic fracturing and drinking water, and adequately described the
findings of such published data in the draft Assessment Report. However, the SAB has concerns
regarding various aspects of the draft Assessment Report, including concerns regarding several major
findings presented within the draft that seek to draw national-level conclusions regarding the impacts of
hydraulic fracturing on drinking water resources. The SAB has recommendations for changes to text in
the draft Assessment Report and for follow-on activities to address gaps. Also included, as Appendix B,
is a dissenting view from four of the 30 members of the SAB Panel regarding the broader SAB Panel's
viewpoint on one of the EPA's major findings.
The SAB's key findings and recommendations are summarized below.
Clarity of and Support for Major Findings: The SAB has concerns regarding the clarity and adequacy
of support for several major findings presented within the draft Assessment Report that seek to draw
national-level conclusions regarding the impacts of hydraulic fracturing on drinking water resources.
The SAB is concerned that these major findings as presented within the Executive Summary are
ambiguous and appear inconsistent with the observations, data, and levels of uncertainty presented and
discussed in the body of the draft Assessment Report. Of particular concern in this regard is the high-
level conclusion statement on page ES-6 that "We did not find evidence that these mechanisms have led
to widespread, systemic impacts on drinking water resources in the United States." The SAB finds that
the EPA did not support quantitatively its conclusion about lack of evidence for widespread, systemic
impacts of hydraulic fracturing on drinking water resources, and did not clearly describe the system(s) of
interest (e.g., groundwater, surface water), the scale of impacts (i.e., local or regional), nor the
definitions of "systemic" and "widespread." The SAB observes that the statement has been interpreted
by readers and members of the public in many different ways. The SAB concludes that if the EPA
retains this conclusion, the EPA should provide quantitative analysis that supports its conclusion that
hydraulic fracturing has not led to widespread, systemic impacts on drinking water resources. Twenty-
six of the 30 members of the SAB Panel concluded that the statement also requires clarification and
additional explanation (e.g., discuss what is meant by "any observed change" in the definition of
"impact" in Appendix J, and consider including modifying adjectives before the words "widespread,
systemic impact" in the statement on page ES-6). Four members of the SAB Panel concluded that this
statement is clear, concise and accurate.
The SAB recommends that the EPA revise the major statements of findings in the Executive Summary
and elsewhere in the final Assessment Report to clearly link these statements to evidence provided in the
body of the final Assessment Report. The EPA should consider prioritizing the major findings that have
been identified within Chapters 4-9 of the final Assessment Report according to expectations regarding
the magnitude of the potential impacts of hydraulic fracturing-related activities on drinking water
resources. The SAB also recommends that the EPA discuss the significant data limitations and
uncertainties, as documented in the body of the draft Assessment Report, when presenting the major
findings. Regarding the EPA's findings of gaps and uncertainties in publicly available data that the
agency relied upon to develop conclusions within the draft Assessment Report, the EPA should clarify
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and describe the different databases that contain such data and the challenges of accessing them, and
make recommendations on how these databases could be improved to facilitate more efficient
investigation of the data they contain.
The final Assessment Report should make clear that while the hydraulic fracturing industry is rapidly
evolving, with changes in the processes being employed, the Assessment necessarily was developed
with the data available at a point in time.
Recognition of Local Impacts: The SAB finds that the EPA's initial goal of assessing the HFWC using
national-level analyses and perspective was appropriate. However, the final Assessment Report should
also recognize that many stresses to surface or groundwater resources associated with stages of the
HFWC are often localized in space and temporary in time but nevertheless can be important and
significant. For example, the impacts of water acquisition will predominantly be observed locally at
small space and time scales. These local-level impacts, when they occur, have the potential to be severe,
and the final Assessment Report needs to better recognize the importance of local impacts. In this
regard, the SAB recommends that the agency should include and critically analyze the status, data on
potential releases, and any available findings from the EPA and state investigations conducted in
Dimock, Pennsylvania; Pavillion, Wyoming; and Parker County, Texas, where many members of the
public have stated that hydraulic fracturing activities have caused local impacts to drinking water
resources. Examination of these high-visibility cases is important so that the reader can more fully
understand the status of investigations in these areas, conclusions associated with the investigations,
lessons learned, if any, for the different stages of the hydraulic fracturing water cycle, what additional
work should be done to improve the understanding of these sites and the HFWC, plans for remediation,
if any, and the degree to which information from these case studies can be extrapolated to other
locations.
Prospective Case Studies: The SAB is concerned that the EPA had planned to but did not conduct
various assessments, field studies, and other research, and the SAB recommends that the EPA delineate
these planned activities within the final Assessment Report and discuss why they were not conducted or
completed. All but two Panel members find the lack of prospective case studies as originally planned by
the EPA and described in the research 2011 Study Plan is a limitation of the draft Assessment Report.
Probability and Risk of Failure Scenarios: To help the reader understand the most significant failure
mechanisms associated with the various stages in the HFWC, the EPA should clearly describe the
probability, risk and relative significance of potential hydraulic fracturing-related failure mechanisms,
and the frequency of occurrence and most likely magnitude and/or probability of risk of water quality
impacts associated with such failure mechanisms. For example, the agency should include additional
major findings associated with the higher likelihood of impacts to drinking water resources associated
with hydraulic fracturing well construction, well integrity, and well injection problems. These findings
should discuss factors and effects regarding the severity and frequency of potential impacts from poor
cementation techniques, hydraulic fracturing operator error, migration of hydraulic fracturing chemicals
from the deep subsurface, and abandoned/orphaned oil and gas wells. The agency should also provide
more information regarding the extent or potential extent of the effects of chemical mixing processes
from hydraulic fracturing operations on drinking water supplies. The EPA should provide additional
detail on the extent and duration of the impacts of spilled liquids and releases of flowback and produced
waters when they occur. Furthermore, the agency should also include additional major findings
associated with the effects on drinking water resources of large spill events that escape site containment,
and sustained, undetected leaks.
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Chemical Toxicity and Hazard: The agency should compile toxicological information on constituents
(e.g., chemicals, dissolved compounds and ions, and particulates) employed in hydraulic fracturing in a
more inclusive manner, and not limit the selection of hydraulic fracturing constituents of concern to
those that have noncancer oral reference values (RfVs) and cancer oral slope factors (OSFs) that were
peer reviewed only by a governmental or intergovernmental source. The agency should use a broad
range of toxicity data, including information pertinent to subchronic exposures from a number of
reliable sources cited by the SAB in addition to those used in the draft Assessment Report to conduct
hazard evaluation for hydraulic fracturing constituents. As the agency broadens inclusion of
toxicological information to populate missing toxicity data, the EPA can expand the tiered hierarchy of
data described in the draft Assessment Report to give higher priority to constituents with RfVs without
excluding other quality toxicological information that is useful for hazard and risk assessment purposes.
Also, an important limitation of the agency's hazard evaluation of constituents across the HFWC is the
agency's lack of analysis of the most likely exposure scenarios and hazards associated with hydraulic
fracturing activities. To help prioritize future research and risk assessment efforts, the agency should
identify the most likely exposure scenarios and hazards and obtain toxicity information relevant to these
exposure scenarios. The EPA provides a wide range of possible scenarios along the HFWC, but more
emphasis is needed on identifying the most likely durations and routes of exposures of concern so that
the EPA can determine what toxicity information is most relevant and focus its research and monitoring
efforts on the most important and/or likely scenarios. The SAB concludes that the selection of likely
scenarios should be based on consideration of findings in prospective and retrospective site
investigations, as well as case studies of public and private wells and surface water supplies impacted by
spills or discharges of flowback, produced water or treated or partially treated wastewater from HFWC
operations. Furthermore, the EPA developed a multi-criteria decision analysis (MCDA) approach to
analyze hydraulic fracturing constituents and identify/prioritize those of most concern. In light of the
limitations described in the SAB's response to Charge Question 7, and given that the EPA applied this
approach to very few constituents, the EPA should explicitly state that these MCDA results (based only
on constituents with RfVs) should not be used to prioritize the constituents of most concern nationally,
nor to identify future toxicity testing research needs.
Characteristics of HF Fluids: For the sake of clarity, the final Assessment Report should distinguish
between hydraulic fracturing constituents injected into a hydraulic fracturing well vs. constituents that
come out of the hydraulic fracturing well in produced fluids, and between those constituents and
potential impacts unique to hydraulic fracturing oil and gas extraction from those that also exist as a
component of conventional oil and gas development, or those constituents that are naturally occurring in
the formation waters of the production zone. The agency should also clarify whether constituents
identified as being of most concern in produced water are products of the hydraulic fracturing activity,
initial flowback, or later-stage produced water, or are constituents of concern derived from oil and gas
production activities that are not unique to hydraulic fracturing activity or are naturally occurring in the
formation water. This will help inform the readers about the different characteristics of HF injection
flowback and produced waters and in-situ subsurface constituents relative to formation water produced
in conventional oil and gas development.
The SAB finds that the data presented by the EPA within Chapter 5 of the Assessment Report indicate
that spills occur at hydraulic fracturing sites; that there are varying causes, composition, frequency,
volume, and severity of such spills; and that little is known about certain hydraulic fracturing
constituents and their safety. The SAB also finds that the EPA's conclusion based on these limited data
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(i.e., that the risk to drinking water supplies from this stage of the HFWC is not substantial) is not
supported or linked to data presented in the body of the draft Assessment Report. The EPA should revise
its interpretation of these limited data. In addition, Chapter 8's summary of water quality characteristics
of hydraulic fracturing wastewaters from various sites clearly indicates that spills or discharges of
inadequately treated hydraulic fracturing wastewater could result in significant adverse impacts on
drinking water quality.
The EPA uses FracFocus 1.0 as the primary source of information on the identity and frequency of use
of constituents in hydraulic fracturing processes, and the SAB expresses concern that the FracFocus
database may not be sufficient. Although the agency acknowledged limitations of the FracFocus data,
the EPA can do more to address these limitations by characterizing available toxicology data on
proprietary constituents, and by using information provided in updated versions of FracFocus on
chemical class, type, mass and concentration.
Baseline Water Quality Data: The EPA should discuss the importance of background and preexisting
chemistry of surface and groundwater in developing a better understanding of whether impacts from
drilling and completion activities can be identified. A major public concern is the appearance of
contaminated or degraded drinking water in wells in areas where hydraulic fracturing occurs. Since
naturally occurring contaminants and degraded drinking water in wells can occur from issues not related
to hydraulic fracturing, the EPA should also include additional discussion on how background and pre-
existing baseline chemistry of surface and groundwater data are used to better understand the impacts of
hydraulic fracturing-related spills and leaks. The scientific complexity of baseline sampling and data
interpretation should be clearly and concisely described.
Approach for Assessing Water Quality and Quantity Impacts: The SAB provides several
suggestions to improve the agency's approach for assessing the potential that the hydraulic fracturing
water cycle processes for oil and gas production may change the quality or quantity of drinking water
resources. While the draft Assessment Report comprehensively summarizes available information
concerning the sources and quantities of water used during HFWC operations from surface water,
groundwater, and treated HFWC wastewaters, the SAB finds that the potential for water availability
impacts on drinking water resources is greatest in areas with high hydraulic fracturing water use, low
water availability, and frequent drought. The SAB notes, but did not independently confirm, the EPA
conclusion that there are important gaps in the data available to assess water use that limit understanding
of hydraulic fracturing potential impacts on water acquisition.
Definition of Proximity: The final Assessment Report should discuss the agency's rationale for
selecting a one-mile radius to define proximity of a drinking water resource to hydraulic fracturing
operations, and the potential need to consider drinking water resources at distances greater than one mile
from a hydraulic fracturing operation. The EPA should present more information regarding the vertical
distance between surface-water bodies and the target zones being fractured, the depths of most existing
and potential future water-supply aquifers compared to the depths of most hydraulically fractured wells,
and the increased potential, if any, for impacts on drinking water quality in aquifers. In regard to
potential impacts on aquifers, of particular interest are situations where the vertical distance between the
hydraulically fractured production zone and a current or future drinking water source is relatively small
depending on local hydrogeological conditions.
Treatment of Hydraulic Fracturing Wastewater: The agency should provide clearer information on
the fundamentals of certain hydraulic fracturing wastewater treatment processes, and the occurrence and
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removal of disinfection by-product precursors in addition to bromide. The agency should describe the
basis for nationwide estimates of hydraulic fracturing-related wastewater production, various aspects of
hydraulic fracturing-waste disposal, the locations of hydraulic fracturing-related wastewater treatment
and disposal facilities relative to downstream public water supply intakes and wells, the impacts of water
recycling on pollutant concentrations and their potential impacts on drinking water quality should spills
of recycled water occur, and trends in hydraulic fracturing-related wastewater disposal methods and
their potential impacts on drinking water resources.
Best Management Practices and the Applicable Regulatory Framework: To better inform the
readers on available processes, methods and technologies that can minimize hydraulic fracturing's
potential impacts to drinking water resources, the SAB recommends that the agency describe best
management practices used by industry at each stage of the HFWC. The EPA should also discuss: (1)
federal, state and tribal standards and regulations implemented with the aim of minimizing the potential
impacts to drinking water resources associated with hydraulic fracturing operations, and (2) the
evolution of oilfield and federal, state and tribal regulatory practices relevant to HFWC activities. The
EPA may develop these summaries as a longer-term future activity.
Accessibility of the Assessment to a Broad Audience: The SAB recommends that the draft
Assessment Report be revised to make it more suitable for a broad audience. It is important that the
Assessment Report, and especially the Executive Summary, be understandable to the general public. The
SAB makes specific recommendations about opportunities to define terms, provide illustrations, and
clarify ambiguities.
In the enclosed report, the SAB provides a number of specific recommendations to improve the clarity
and scientific basis of the EPA's analyses within the EPA's draft Assessment Report, as well as
recommendations that the agency may consider longer-term activities to conduct after finalization of the
Assessment Report.
The SAB appreciates the opportunity to provide the EPA with advice on this important subject. We look
forward to receiving the agency's response.
Sincerely,
/Signed/
/Signed/
Dr. Peter S. Thorne
Chair
Dr. David A. Dzombak
Chair
SAB Hydraulic Fracturing Research Advisory Panel
Science Advisory Board
Enclosure
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NOTICE
This report has been written as part of the activities of the EPA Science Advisory Board, a public
advisory group providing extramural scientific information and advice to the Administrator and other
officials of the Environmental Protection Agency. The Board is structured to provide balanced, expert
assessment of scientific matters related to the problems facing the agency. This report has not been
reviewed for approval by the agency and, hence, the contents of this report do not 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 or commercial products constitute a
recommendation for use. Reports of the EPA Science Advisory Board are posted on the EPA website at
http ://www. epa. gov/ sab.
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U.S. Environmental Protection Agency
Science Advisory Board
Hydraulic Fracturing Research Advisory Panel
CHAIR
Dr. David A. Dzombak, Hamerschlag University Professor and Head, Department of Civil and
Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA
MEMBERS
Dr. Stephen W. Almond, Director of Research & Development, Fritz Industries, Inc., Houston, TX
Dr. E. Scott Bair, Emeritus Professor, School of Earth Sciences, Ohio State University, Columbus, OH
Dr. Peter Bloomfield, Professor, Statistics Department, North Carolina State University, Raleigh, NC
Dr. Steven R. Bohlen, State Oil and Gas Supervisor, and Head of the Division of Oil, Gas and
Geothermal Resources (DOGGR), State of California Department of Conservation, Sacramento, CA
Dr. Elizabeth W. Boyer, Associate Professor, Department of Ecosystem Science & Management,
Pennsylvania State University, University Park, PA
Dr. Susan L. Brantley, Distinguished Professor of Geosciences and Director, Earth and Environmental
Systems Institute, Pennsylvania State University, University Park, PA
Dr. James V. Bruckner, Professor of Pharmacology and Toxicology, Department of Pharmaceutical
and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA
Dr. Thomas L. Davis, Professor, Department of Geophysics, Colorado School of Mines, Golden, CO
Dr. Joseph J. DeGeorge, Global Head of Safety Assessment and Laboratory Animal Resources, Merck
Research Laboratories, Lansdale, PA
Dr. Joel Ducoste, Professor, Department of Civil, Construction, and Environmental Engineering, North
Carolina State University, Raleigh, NC
Dr. Shari Dunn-Norman, Professor, Geosciences and Geological and Petroleum Engineering
Department, Missouri University of Science and Technology, Rolla, MO
Dr. Katherine Bennett Ensor, Professor, Department of Statistics, Rice University, Houston, TX
Dr. Elaine M. Faustman, Professor, Department of Environmental and Occupational Health Sciences,
and Director, Institute for Risk Analysis and Risk Communication, School of Public Health, University
of Washington, Seattle, WA
Mr. John V. Fontana, Professional Geologist and President, Vista GeoScience LLC, Golden, CO
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Dr. Daniel J. Goode, Research Hydrologist, U.S. Geological Survey, Pennsylvania Water Science
Center, Exton, PA
Dr. Bruce D. Honeyman, Associate Vice President for Research and Emeritus Professor of
Environmental Science and Engineering, Colorado School of Mines, Golden, CO
Mr. Walter R. Hufford, Director of Government and Regulatory Affairs, Talisman Energy USA Inc. -
REPSOL, Warrendale, PA
Dr. Richard F. Jack, Director, Vertical Marketing for Environmental and Industrial Markets, Thermo
Fisher Scientific Inc., San Jose, CA
Dr. Dawn S. Kaback, Principal Geochemist, Amec Foster Wheeler, Denver, CO
Dr. Abby A. Li, Senior Managing Scientist, Exponent Health Sciences, Exponent, Inc., San Francisco,
CA
Mr. Dean N. Malouta, White Mountain Energy Consulting, LLC, Houston, TX
Dr. Cass T. Miller, Daniel A. Okun Distinguished Professor of Environmental Engineering,
Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC
Dr. Laura J. Pyrak-Nolte, Professor, Department of Physics, College of Science, Purdue University,
West Lafayette, IN
Dr. Stephen J. Randtke, Professor, Department of Civil, Environmental, and Architectural
Engineering, University of Kansas, Lawrence, KS
Dr. Joseph N. Ryan, Professor of Environmental Engineering and Bennett-Lindstedt Faculty Fellow,
Department of Civil, Environmental, and Architectural Engineering, University of Colorado-Boulder,
Boulder CO
Dr. James E. Saiers, Clifton R. Musser Professor of Hydrology and Associate Dean of Academic
Affairs, School of Forestry and Environmental Studies, Yale University, New Haven, CT
Dr. Azra N. Tutuncu, Professor and Harry D. Campbell Chair, Petroleum Engineering Department, and
Director, Unconventional Natural Gas and Oil Institute, Colorado School of Mines, Golden, CO
Dr. Paul K. Westerhoff, Senior Advisor to the Provost for Engineering & Science, and Professor,
School of Sustainable Engineering and The Built Environment, Ira A. Fulton Schools of Engineering,
Arizona State University, Tempe, AZ
Dr. Thomas M. Young, Professor of Civil and Environmental Engineering, University of California -
Davis, Davis, CA
SCIENCE ADVISORY BOARD STAFF
Mr. Edward Hanlon, Designated Federal Officer, U.S. Environmental Protection Agency, Science
Advisory Board Staff, Washington, DC
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U.S. Environmental Protection Agency
Science Advisory Board
BOARD
CHAIR
Dr. Peter S. Thorne, Professor and Head, Department of Occupational & Environmental Health,
College of Public Health , University of Iowa, Iowa City, IA
MEMBERS
Dr. Joseph Arvai, Max McGraw Professor of Sustainable Enterprise and Director, Erb Institute, School
of Natural Resources & Environment, University of Michigan, Ann Arbor, MI
Dr. Kiros T. Berhane, Professor, Preventive Medicine, Keck School of Medicine, University of
Southern California, Los Angeles, CA
Dr. Sylvie M. Brouder, Professor and Wickersham Chair of Excellence in Agricultural Research,
Department of Agronomy, Purdue University, West Lafayette, IN
Dr. Ingrid Burke, Director and Wyoming Excellence Chair, Haub School and Ruckelshaus Institute of
Environment and Natural Resources, University of Wyoming, Laramie, WY
Dr. Ana V. Diez Roux, Dean, School of Public Health, Drexel University, Philadelphia, PA
Dr. Michael Dourson, Director, Toxicology Excellence for Risk Assessment Center, Professor of
Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, OH
Dr. Joel J. Ducoste, Professor, Department of Civil, Construction, and Environmental Engineering,
North Carolina State University, Raleigh, NC
Dr. David A. Dzombak, Hamerschlag University Professor and Head, Department of Civil and
Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA
Dr. Elaine M. Faustman, Professor Department of Environmental and Occupational Health Sciences,
and Director, Institute for Risk Analysis and Risk Communication, School of Public Health, University
of Washington, Seattle, WA
Dr. Susan P. Felter, Research Fellow, Global Product Stewardship, Procter & Gamble, Mason, OH
Dr. R. William Field, Professor, Department of Occupational and Environmental Health, and
Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA
Dr. H. Christopher Frey, Glenn E. Futrell Distinguished University Professor, Department of Civil,
Construction and Environmental Engineering, College of Engineering, North Carolina State University,
Raleigh, NC
Dr. Steven Hamburg, Chief Scientist, Environmental Defense Fund, Boston, MA
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Dr. Cynthia M. Harris, Director and Professor, Institute of Public Health, Florida A&M University,
Tallahassee, FL
Dr. Robert J. Johnston, Director of the George Perkins Marsh Institute and Professor, Department of
Economics, Clark University, Worcester, MA
Dr. Kimberly L. Jones, Professor and Chair, Department of Civil and Environmental Engineering,
Howard University, Washington, DC
Dr. Catherine J. Karr, Associate Professor - Pediatrics and Environmental and Occupational Health
Sciences and Director - NW Pediatric Environmental Health Specialty Unit, University of Washington,
Seattle, WA
Dr. Madhu Khanna, ACES Distinguished Professor in Environmental Economics, Department of
Agricultural and Consumer Economics, University of Illinois at Urbana-Champaign, Urbana, IL
Dr. Francine Laden, Mark and Catherine Winkler Associate Professor of Environmental
Epidemiology, Harvard School of Public Health, and Channing Division of Network Medicine, Brigham
and Women's Hospital and Harvard Medical School, Boston, MA
Dr. Lois Lehman-McKeeman, Distinguished Research Fellow, Discovery Toxicology, Bristol-Myers
Squibb, Princeton, NJ
Dr. Robert E. Mace, Deputy Executive Administrator, Water Science & Conservation, Texas Water
Development Board, Austin, TX
Dr. Mary Sue Marty, Senior Toxicology Leader, Toxicology & Environmental Research, The Dow
Chemical Company, Midland, MI
Dr. Denise Mauzerall, Professor, Woodrow Wilson School of Public and International Affairs, and
Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ
Dr. Kristina D. Mena, Associate Professor, Epidemiology, Human Genetics, and Environmental
Sciences, School of Public Health, University of Texas Health Science Center at Houston, El Paso, TX
Dr. Surabi Menon, Director of Research, ClimateWorks Foundation, San Francisco, CA
Dr. James R. Mihelcic, Samuel L. and Julia M. Flom Professor, Civil and Environmental Engineering,
University of South Florida, Tampa, FL
Dr. H. Keith Moo-Young, Chancellor, Office of Chancellor, Washington State University, Tri-Cities,
Richland, WA
Dr. Kari Nadeau, Naddisy Family Foundation Professor of Medicine, Director, FARE Center of
Excellence at Stanford University and Sean N. Parker Center for Allergy and Asthma Research at
Stanford University School of Medicine, Stanford, CA
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Dr. James Opaluch, Professor and Chair, Department of Environmental and Natural Resource
Economics, College of the Environment and Life Sciences, University of Rhode Island, Kingston, RI
Dr. Thomas F. Parkerton, Senior Environmental Associate, Toxicology & Environmental Science
Division, ExxonMobil Biomedical Science, Houston, TX
Mr. Richard L. Poirot, Independent Consultant, Burlington, VT
Dr. Kenneth M. Portier, Vice President, Department of Statistics & Evaluation Center, American
Cancer Society, Atlanta, GA
Dr. Kenneth Ramos, Associate Vice-President of Precision Health Sciences and Professor of Medicine,
Arizona Health Sciences Center, University of Arizona, Tucson, AZ
Dr. David B. Richardson, Associate Professor, Department of Epidemiology, School of Public Health,
University of North Carolina, Chapel Hill, NC
Dr. Tara L. Sabo-Attwood, Associate Professor and Chair, Department of Environmental and Global
Health, College of Public Health and Health Professionals, University of Florida, Gainesville, FL
Dr. William Schlesinger, President Emeritus, Cary Institute of Ecosystem Studies, Millbrook, NY
Dr. Gina Solomon, Deputy Secretary for Science and Health, Office of the Secretary, California
Environmental Protection Agency, Sacramento, CA
Dr. Daniel O. Stram, Professor, Department of Preventive Medicine, Division of Biostatistics,
University of Southern California, Los Angeles, CA
Dr. Jay Turner, Associate Professor, Department of Energy, Environmental & Chemical Engineering,
Campus Box 1180, Washington University, St. Louis, MO
Dr. Edwin van Wijngaarden, Associate Professor, Department of Public Health Sciences, School of
Medicine and Dentistry, University of Rochester, Rochester, NY
Dr. Jeanne M. VanBriesen, Professor, Department of Civil and Environmental Engineering, Carnegie
Mellon University, Pittsburgh, PA
Dr. John Vena, Professor and Founding Chair, Department of Public Health Sciences, Medical
University of South Carolina, Charleston, SC
Dr. Elke Weber, Jerome A. Chazen Professor of International Business, Columbia Business School,
New York, NY
Dr. Charles Werth, Professor and Bettie Margaret Smith Chair in Environmental Health Engineering,
Department of Civil, Architectural and Environmental Engineering, Cockrell School of Engineering,
University of Texas at Austin, Austin, TX
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Dr. Peter J. Wilcoxen, Professor, Public Administration and International Affairs, The Maxwell
School, Syracuse University, Syracuse, NY
Dr. Robyn S. Wilson, Associate Professor, School of Environment and Natural Resources, Ohio State
University, Columbus, OH
SCIENCE ADVISORY BOARD STAFF
Mr. Thomas Carpenter, Designated Federal Officer, U.S. Environmental Protection Agency, Science
Advisory Board, Washington, DC
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TABLE OF CONTENTS
Acronyms and Abbreviations ix
1. EXECUTIVE SUMMARY 1
2. INTRODUCTION 25
2.1. Background 25
2.2. SAB Review 25
3. RESPONSES TO THE EPA's CHARGE QUESTIONS 27
3.1. Goals, Background and History of the Assessment 27
3.2. Water Acquisition Stage in the III WC 31
3.3. Chemical Mixing Stage in the HFWC 41
3.4. Well Injection Stage in the III WC 51
3.5. Flowback and Produced Water Stage in the HFWC 69
3.6. Wastewater Treatment and Waste Disposal Stage in the III WC 94
3.7. Chemicals Used or Present in Hydraulic Fracturing Fluids 114
3.8. Synthesis of Science on Potential Impacts of Hydraulic Fracturing on Drinking
Water Resources, and Executive Summary 129
REFERENCES 138
APPENDIX A-EPA'S CHARGE QUESTIONS A-l
APPENDIX B-DISSENTING OPINION B-l
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Acronyms and Abbreviations
ACToR
Aggregated Computational Toxicology Resource Database
AT SDR
Agency for Toxic Substances and Disease Registry
BMP
Best Management Practices
BOD
Biochemical Oxygen Demand
Br
Bromine
BTEX
Benzene, Toluene, Ethylbenzene, and Xylenes
CBI
Confidential Business Information
CBM
Coal Bed Methane
CI
Chlorine
CI- / Br
Chlorine/Bromine Ion Ratio
CI" /1-
Chlorine/Iodine Ion Ratio
COGCC
Colorado Oil and Gas Conservation Commission
CWA
Clean Water Act
CWT
Centralized Wastewater Treatment
CWTFs
Centralized Wastewater Treatment Facilities
DOE
U.S. Department of Energy
DBP
Disinfection By-Product
EPA
U.S. Environmental Protection Agency
FDA
U.S. Food and Drug Administration
GIS
Geographic Information System
GLP
General Laboratory Practices
HAA
Haloacetic Acid
HF
Hydraulic Fracturing
HFWC
Hydraulic Fracturing Water Cycle
Kow
Octanol-Water Partition Coefficient
MCDA
Multi-Criteria Decision Analysis
MCLs
Maximum Contaminant Levels
MCLGs
Maximum Contaminant Level Goals
mg/L
Milligrams per Liter
MRLs
Minimal Risk Levels
NAS
National Academy of Sciences
NDMA
N-Nitrosodimethylamine
NGO
Non-Governmental Organization
NPDES
National Pollutant Discharge Elimination System
OECD
Organisation for Economic Co-operation and Development
ORD
EPA Office of Research and Development
OSFs
Cancer Oral Slope Factors
POTW
Publicly Owned Treatment Works
pCi/L
Picocuries per Liter
PWS
Public Water Supply
PWSS
Public Water Supply Systems
RCRA
Resource Conservation and Recovery Act
RfDs
Chronic Reference Doses
RfV
Reference Value
SAB
EPA Science Advisory Board
Sr
Strontium
TDS
Total Dissolved Solids
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TENORMS
Technologically-Enhanced Naturally Occurring Radioactive Materials
THM
Trihalomethane
TLVs
Threshold Limit Values
TOC
Total Organic Carbon
TOX
Total Organic Halide
TTC
Threshold of Toxicological Concern
UIC
Underground Injection Control
USGS
U.S. Geological Survey
VOCs
Volatile Organic Compounds
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1. EXECUTIVE SUMMARY
Overview
The EPA's Office of Research and Development (ORD) requested that the Science Advisory Board
(SAB) conduct a peer review and provide advice on scientific charge questions associated with the
EPA's draft Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking
Water Resources (ExternalReview Draft, EPA/600/R-15/047, June 2015) (hereafter, the "draft
Assessment Report"). The draft Assessment Report synthesizes available scientific literature and data on
the potential for the hydraulic fracturing water cycle processes involved in oil and gas production to
impact the quality or quantity of drinking water resources, and identifies factors affecting the frequency
or severity of any potential impacts.
The EPA developed the draft Assessment Report in response to a request in 2009 from the United States
Congress, which urged the EPA to examine the relationship between hydraulic fracturing and drinking
water resources. The EPA consulted with stakeholders, and developed a Research Scoping document
followed by a detailed research Study Plan, both of which were reviewed by the SAB, in 2010 and in
2011, respectively. An EPA Progress Report on the study detailing the research approaches, activities,
and remaining work was released in late 2012. A consultation on the Progress Report was conducted in
May 2013 with members of SAB's Hydraulic Fracturing Research Advisory Panel (the Panel). The
EPA's draft Assessment Report was released in June 2015 for public comment and review by the Panel.
The EPA used literature and the results from the EPA's research projects to develop the draft
Assessment Report.
The EPA examined over 3,500 individual sources of information, and cited over 950 of these sources in
the draft Assessment Report. The sources of data that the EPA evaluated included articles published in
science and engineering journals, federal and state reports, non-governmental organization reports, oil
and gas industry publications, other publicly available data and information, including confidential and
non-confidential business information, submitted by industry to the EPA. The draft Assessment Report
also includes citation of relevant literature developed as part of the EPA's research Study Plan (U.S.
EPA 2011).
At a series of public meetings held in the last quarter of 2015 and the first quarter of 2016, the SAB
Panel reviewed the draft Assessment Report and considered many oral and written public comments to
develop advice on the scientific adequacy of the EPA's draft Assessment Report. The SAB encourages
the EPA to review and consider the public comments received as it finalizes the draft Assessment
Report. At a public meeting on June 14, 2016, the chartered SAB deliberated on the SAB Panel's draft
report and agreed that chair and the lead reviewers on the chartered SAB would work with the chair of
the SAB Panel to revise the draft SAB report in accordance with discussions at the June 14, 2016 public
meeting. The body of this report provides the advice and recommendations of the SAB.
The SAB was asked to provide advice and comment on various aspects of the EPA's draft Assessment
Report through responses to eight charge questions. The multi-part charge questions were formulated to
follow the structure of the assessment, including the introduction, the descriptions of hydraulic
fracturing activities and drinking water resources, the individual stages in the hydraulic fracturing water
cycle (HFWC), the identification and hazard evaluation of hydraulic fracturing constituents (e.g.,
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chemicals, dissolved compounds and ions, and particulates), and the overall synthesis of the materials
presented in the assessment.
The enclosed report provides detailed comments and recommendations for improving the draft
Assessment Report, as well as recommendations that the agency may consider longer-term activities that
may be conducted after finalization of the Assessment Report. Also included, as Appendix B, is a
dissenting view from four of the 30 members of the Panel associated with a position taken by the SAB
Panel with respect to one of the EPA's major findings. The SAB's key findings and recommendations
are summarized below.
In general, the SAB finds the EPA's overall approach to assess the potential impacts of hydraulic
fracturing water cycle processes involved in oil and gas production on drinking water resources,
focusing on the individual stages in the HFWC, to be comprehensive but lacking in several critical areas.
The SAB also finds that the agency provided a generally comprehensive overview of the available
literature that describes the factors affecting the relationship of hydraulic fracturing and drinking water,
and adequately described the findings of such published data in the draft Assessment Report. However,
the SAB has concerns regarding various aspects of the draft Assessment Report and has
recommendations for changes to its text and follow-on activities to address gaps that the SAB has
identified.
The SAB recognizes that there are a large number of recommendations included in the body of the SAB
report. The SAB has identified recommendations that the agency may consider longer-term future
activities that the agency can conduct after finalization of the Assessment Report. The SAB recommends
that the agency describe the additional research needed to adequately assess knowledge and information
gaps for the HFWC stages and include this in Chapter 10 or in a chapter that the EPA would add to the
final Assessment Report on ongoing research, and data and research needs.
Thematic Areas for Improving the Draft Assessment Report
The SAB report is organized around the chapters of the draft Assessment Report, which correspond to
the identified stages of the HFWC. However, the SAB identified the following cross-cutting thematic
areas for improvement of the draft Assessment Report, presented by topic area below.
Revisions to the Assessment's Statements on Major Findings
In its draft Assessment Report, the agency sought to draw national-level conclusions regarding the
impacts of hydraulic fracturing on drinking water resources. The SAB finds that several major summary
findings do not clearly, concisely, and accurately describe the findings as developed in the chapters of
the draft Assessment Report, and that these findings are not adequately supported with data or analysis
from within the body of the draft Assessment Report. The SAB finds that these major findings are
presented ambiguously within the Executive Summary and appear inconsistent with the observations,
data, and levels of uncertainty presented and discussed in the body of the text.
The SAB expresses particular concern regarding the draft Assessment Report's high-level conclusion on
page ES-6 that "We did not find evidence that these mechanisms have led to widespread, systemic
impacts on drinking water resources in the United States." The SAB finds that the EPA did not support
quantitatively its conclusion about lack of evidence for widespread, systemic impacts of hydraulic
fracturing on drinking water resources, and did not clearly describe the system(s) of interest (e.g.,
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groundwater, surface water), the scale of impacts (i.e., local or regional), nor the definitions of
"systemic" and "widespread". The SAB observes that the statement has been interpreted by readers and
members of the public in many different ways. The SAB concludes that if the EPA retains this
conclusion, the EPA should provide quantitative analysis that supports its conclusion that hydraulic
fracturing has not led to widespread, systemic impacts on drinking water resources. Most Panel
members also conclude that the statement requires clarification and additional explanation (e.g.,
consider including possible modifying adjectives before the words "widespread, systemic impact" in the
statement on page ES-6). The SAB also concludes that the EPA should carefully consider whether to
revise the definition of impact as provided in Appendix J of the draft Assessment Report (e.g., discuss
what is meant by "any observed change" in the definition of "impact" in Appendix J). Four of the 30
Panel members find that this statement on page ES-6 is acceptable as written, but note that the EPA
should have provided a more robust discussion on how it reached this conclusion. Further details
regarding these four Panel members' opinion are noted in Appendix B to this Report.
The agency should strengthen the Executive Summary and Chapter 10 Synthesis by linking the stated
findings more directly to evidence presented in the body of the draft Assessment Report. The EPA
should more precisely describe each of the major findings of the draft Assessment Report, in both the
Executive Summary and Chapter 10 Synthesis, including specific cases of drinking water impacts that
relate to these major findings. The EPA should consider prioritizing the major findings that have been
identified within Chapters 4-9 of the final Assessment Report according to expectations regarding the
magnitude of the potential impacts of hydraulic fracturing-related activities on drinking water resources.
The agency should revise the synthesis discussion in Chapter 10 to present integrated conclusions, rather
than a summary of findings from Chapters 4-9. The draft Assessment Report compartmentalizes the
major stages of the HFWC into separate chapters. This compartmentalization is preserved in the
Synthesis. As a result, implications that stem from integration of the major findings and potential issues
that cut across chapters of the draft Assessment Report go largely unexplored. Integrated conclusions are
needed. The agency should also revise Chapter 10 to discuss methods to reduce uncertainties related to
the HFWC, including ongoing research, and data and research needs.
More Attention to Local Impacts
The SAB finds that the EPA's initial goal of assessing the HFWC using national-level analyses and
perspective was appropriate. However, the final Assessment Report should recognize that many stresses
to surface or groundwater resources associated with stages of the HFWC are often localized in space and
temporary in time but can nevertheless be important and significant. For example, the impacts of water
acquisition will predominantly be felt locally at small space and time scales. These local-level potential
impacts have the potential to be severe, and the final Assessment Report needs to better characterize and
recognize the importance of local impacts, especially since locally important impacts are unlikely to be
captured in a national-level summary of impacts.
With regard to local impacts, the SAB recommends that the agency include and explain the status, data
on potential releases, and findings if available, for the EPA and state investigations conducted in
Dimock, Pennsylvania; Pavillion, Wyoming; and Parker County, Texas, where many members of the
public have stated that hydraulic fracturing activities have caused local impacts to drinking water
resources. Examination of these high-visibility cases is important so that the reader can more fully
understand the status of investigations in these areas; conclusions associated with the investigations;
lessons learned, if any, for the different stages of the hydraulic fracturing water cycle; what additional
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work should be done to improve the understanding of these sites with respect to the HFWC; plans for
remediation, if any; and the degree to which information from these case studies can be extrapolated to
other locations.
The SAB is concerned that the EPA had planned to but did not conduct various assessments, field
studies, and other research, and the SAB recommends that the EPA delineate these planned activities
within the final Assessment Report and discuss why they were not conducted or completed. For
example, the EPA had planned to conduct prospective case studies that contemplated drilling
observation wells, collection of groundwater samples and other monitoring before and during drilling,
hydraulic fracturing, and production operations. The goal was to follow the complete development of
production wells, and to collect data prior to, during, and after hydraulic fracturing at the sites. Such
studies would allow EPA to evaluate changes in water quality over time: throughout drilling, injection of
fracturing fluids, flowback, and production. These planned prospective studies were not conducted or
completed by the EPA, and the reasons for not conducting them were not described in the draft
Assessment Report. The datasets collected during planned prospective case studies would have
benefited the EPA's assessment in evaluating changes in water quality over time, if any, and assessing
the fate and transport of HFWC constituents if a release was observed. The SAB finds that the EPA
should evaluate lessons learned from its initial attempts and implementation challenges in developing
the prospective case studies, including how these lessons could inform design of future prospective case
studies.
The SAB concludes that the lack of prospective case studies as originally planned by the EPA and
described in the research 2011 Study Plan is a limitation of the draft Assessment Report, since the
studies would have allowed the EPA to monitor the potential impacts of HF activities on the HFWC to a
level of detail not routinely practiced by industry or required by most state regulations. Such detailed
data would enable EPA to reduce current uncertainties and research gaps regarding the relationship
between hydraulic fracturing and drinking water. Two Panel members do not find the lack of
prospective case studies to be a limitation to the draft Assessment Report, based on the perspective that
investigations conducted by universities, consulting firms, and other external stakeholders could be used
in lieu of the agency conducting such studies.
The SAB recommends that the EPA investigate prospective studies that may have been conducted by
other organizations on site-specific hydraulic fracturing operations to identify research gaps regarding
the relationship between hydraulic fracturing and drinking water resources, and to describe such studies
in the final Assessment Report. The final Assessment Report should identify ongoing and future needs
for research, assessments, and field studies. The EPA, as a longer-term future activity, should continue
research on expanded case studies and long-term prospective case studies in collaboration with
appropriate state and regional regulatory agencies. The SAB finds that the final Assessment Report
should describe the agency's plans for conducting prospective studies and other research that the EPA
had planned but did not conduct as described in the research Study Plan.
The draft Assessment Report provided limited information on the magnitude of hydraulic fracturing
spills from all available sources and used information from two states - Pennsylvania and Colorado - to
estimate the frequency of on-site spills nationwide. The SAB finds that the draft Assessment Report's
analysis of spill data cannot be extrapolated across the entire United States. The SAB recommends that
the agency revisit a broader grouping of states and "refresh" the final Assessment Report with updated
information on the reporting of spills associated with HFWC activities. The draft Assessment Report
does not provide a robust discussion regarding the information yielded from available data on HFWC
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spills, and SAB recommends that the EPA assess and discuss the current status of data reporting on
spills, the nature of hydraulic fracturing fluids, and a more thorough presentation and explanation of the
frequency and types of data reported by the hydraulic fracturing industry. In addition, the SAB finds that
it is essential to have more extensive and reliable information on type, intensity, and duration of
exposures to constituents to determine whether hydraulic fracturing activities in different locales pose
health risks in relation to water quality impacts.
Data Limitations and What Needs to Be Done to Address Such Limitations
Throughout the draft Assessment Report, within discussions for each stage of the HFWC, the EPA notes
that there are data limitations that prevented the EPA from doing analyses that the EPA desired to
conduct. Within these discussions, the EPA should outline the level of data that the EPA would desire in
order for it to conduct an appropriate assessment of that topic area.
For example, based on information in the draft Assessment Report analyses on sources and quantities of
water used in hydraulic fracturing, the SAB notes, but did not independently confirm, the EPA
conclusion that there are gaps and uncertainties in publicly available data upon which the EPA relied .
The agency should, as a longer-term future activity: (1) synthesize information that is collected by the
states but not available in mainstream databases, such as well completion reports, permit applications,
and the associated water management plans; and (2) assess whether there are specific local and regional
aquifers that are particularly impacted by HFWC activities, and if so, provide quantifiable information
on this topic. In the final Assessment Report the agency should describe the scale of the EPA's task for
investigating, gathering and organizing data collected by states and data available from state agencies.
The agency should also describe the challenges associated with conducting this investigation and the
critical lessons learned from the effort. The EPA should also clarify and describe the different databases
that contain relevant data, the challenges of assessing them, and make recommendations on how these
databases could be improved to facilitate more efficient investigation of these databases. Such
descriptions would also provide for greater transparency to external stakeholders.
Data Needs Regarding Constituents of Concern
The SAB finds that the EPA could improve its use of the FracFocus Chemical Disclosure Registry
database. The agency should acknowledge the limited information on the fluids being injected, and
should describe its concerns regarding its reliance on the February 2013 FracFocus version 1.0 for its
findings in the final Assessment Report. The agency should also revise the final Assessment Report to
characterize data on proprietary compounds that the EPA may have, and information provided in
FracFocus on chemical class, type, mass and concentration (i.e., concentration of the constituent, in
terms of % by mass, in the hydraulic fracturing fluid).
In Chapter 9, the EPA presents a Multi-Criteria Decision Analysis (MCDA) approach that the EPA
conceived, designed and formulated as a logical approach for assessing the scope and potential impacts
of hydraulic fracturing on national drinking water resources given that the information used is limited
and fragmented. The SAB finds that the agency should not restrict the criteria for selection of hydraulic
fracturing constituents of concern (or not of concern) to solely constituents that have non-cancer oral
reference values (RfVs) and cancer oral slope factors (OSFs) that were peer reviewed only by a
governmental or intergovernmental source. The agency should expand the criteria for identifying
hydraulic fracturing constituents of concern through use of peer-reviewed toxicity data, including
information pertinent to sub-chronic exposures available from a number of reliable sources. The final
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Assessment Report should explicitly indicate what fraction of the constituents identified in hydraulic
fracturing fluid and/or produced waters have some hazard information (e.g., toxicity data available from
or used by the U.S. federal government, state governments, or international non-governmental
organizations for risk assessment purposes, or publicly available peer-reviewed data), and what fraction
have no available information.
There is uncertainty regarding which hydraulic fracturing constituents are currently in use. A crucial
oversight within the draft Assessment Report is the lack of discussion on the degree of undetected,
unmonitored hydraulic fracturing constituents and analytical assessment of the many uncommon
constituents used in hydraulic fracturing. The SAB recommends that the EPA assess impacts and the
underlying uncertainty associated with these undetected, unmonitored hydraulic fracturing constituents
and incorporate such an assessment into this chapter of the final Assessment Report. This assessment
should also consider how many hydraulic fracturing constituents that are in use do not have analytical
methods, and are not undergoing monitoring.
The SAB recommends that the EPA, in collaboration with state agencies, outline a plan for analyzing
organic compounds in HF flowback and produced waters. Flowback and produced water composition
data are limited and the majority of available data are for inorganics. Furthermore, data are needed on
the formation of disinfection by-products in drinking water treatment plants downstream from
Centralized Wastewater Treatment Facilities (CWTFs) and from Publicly Owned Treatment Works
(POTWs) receiving hydraulic-fracturing-related wastewater. Also, significant releases of bromide from
hydraulic fracturing operations to surface or ground waters subsequently become part of intake water at
downstream drinking water treatment plants and upon disinfection can result in concentrations of
brominated organic compounds that are potentially deleterious to human health due to the formation of
disinfection by-products (DBP). The EPA should discuss whether a bromide salt is ever added as an
injection constituent.
For the sake of clarity, the final Assessment Report should distinguish between hydraulic fracturing
constituents injected into a hydraulically fractured well vs. constituents that come out of the well in
produced fluids. It should also distinguish between those constituents and potential impacts unique to
hydraulic fracturing oil and gas extraction and those that also exist as a component of conventional oil
and gas development or are naturally occurring constituents in the drinking water source or production
zone. The final Assessment Report should also clarify whether constituents identified as being of most
concern in produced water are products of the hydraulic fracturing activity, flowback, or later-stage
produced water, or are constituents of concern derived from oil and gas production activities that are not
unique to hydraulic fracturing activity. This will help inform the readers about the different
characteristics of HF flowback and produced waters and in-situ groundwater constituents as compared to
formation water produced in conventional oil and gas development.
The SAB finds that the data presented by the EPA within Chapter 5 indicate that spills occur at
hydraulic fracturing sites; that there are varying causes, composition, frequency, volume, and severity of
such spills; and that little is known about certain hydraulic fracturing constituents and their safety. The
SAB also finds that the EPA's conclusion based on these limited data (i.e., that the risk to drinking water
supplies from this stage of the HFWC is not substantial) is not supported or linked to data presented in
the body of the draft Assessment Report. The EPA should revise its interpretation of these limited data.
In addition, Chapter 8's summary of water quality characteristics of hydraulic fracturing wastewaters
from various sites clearly indicates that spills or discharges of inadequately treated hydraulic fracturing
wastewater could result in significant adverse impacts on drinking water quality.
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Best Management Practices and Changes in Hydraulic Fracturing Operations
The SAB recognizes that the EPA did not intend for the final Assessment Report to serve as a guide to
best management practices for hydraulic fracturing operations. Nevertheless, it is clear that management
practices can significantly influence the potential for adverse impacts to drinking water resources to
occur, both in terms of frequency and occurrence. Therefore, the SAB recommends that the agency
describe best management practices used by industry at each stage of the HFWC, to better inform the
readers on available processes, methods and technologies that can prevent or minimize hydraulic
fracturing's potential impacts to drinking water resources. Also, the EPA should summarize significant
technological changes that have occurred since 2012 in hydraulic fracturing operations related to the
HFWC (e.g., changes in well construction practices, well integrity testing, and well injection) and assess
the influence of these changes on the frequency and severity of potential impacts to drinking water
resources). This summary of best management practices and technological changes need not be an
exhaustive analysis of such practices and changes. The EPA may develop this summary as an item for
longer-term future activity.
Evolving Regulatory Framework
In Chapter 1, the agency should provide a concise overview discussion of the relevant federal, state and
tribal laws and requirements pertaining to HFWC activities for oil and gas development, and
mechanisms for enforcement of the laws and requirements with respect to protection of surface water
quality, groundwater quality, municipal water supplies, and private wells. The overview should provide
a description of organizations typically responsible for monitoring and regulating HFWC activities, and
describe: (1) federal, state and tribal standards and regulations that have been implemented with the aim
of preventing or minimizing the potential impacts of hydraulic fracturing on drinking water resources;
and (2) changes in oilfield operations and regulations that are relevant to HFWC activities. The final
Assessment Report should make clear that the hydraulic fracturing industry is rapidly evolving, with
changes in the processes being employed, whereas the Assessment necessarily was developed with the
data available at a point in time. The EPA should consider reviewing hydraulic fracturing-related
standards and regulations within a few key states such as Pennsylvania, Wyoming, Texas, Colorado and
California, which all have implemented new hydraulic fracturing-related regulations since 2012. The
EPA could consider the work completed on this topic by the Interstate Oil and Gas Compact
Commission, the State Review of Oil, Natural Gas, Environmental Regulations, Inc. organization, and
the Groundwater Protection Council. This overview discussion of the relevant laws and requirements
need not be an exhaustive analysis of such practices and changes. The EPA may develop this overview
as a longer-term future activity.
Transparency and Clarity of the Assessment
The SAB recommends that the draft Assessment Report be revised to make it more suitable for a broad
audience. As currently written, the Executive Summary is understandable to technical experts in
geoscience and engineering, but will be less clear to a general audience. It is important that the general
public be able to understand the Assessment Report and especially the Executive Summary. The SAB
makes specific recommendations about opportunities to define terms, provide illustrations, clarify
ambiguities, and be more precise in the presentation of major findings. Clearer statements are needed on
the goals and scope of the assessment and on specific descriptions of hydraulic fracturing activities.
Well-designed diagrams and illustrations (including photographs of field site equipment and facilities)
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should be added to enhance the public's understanding of hydraulic fracturing activities and operations.
Technical terms should be used sparingly and should always be defined, and graphics should be
introduced to illustrate and clarify key concepts and processes.
Highlights of Responses to Specific Charge Questions
The SAB provides a number of additional suggestions to improve the agency's approach for assessing
the potential that HFWC activities may change the quality or quantity of drinking water resources.
Among these is a recommendation that the final Assessment Report should identify critical data and
research needs for reducing uncertainties. A more detailed description of the technical recommendations
is included in the body of the SAB report, and the responses to specific charge questions are highlighted
below.
Goals. Background and History of the Assessment (Charge Question 1)
The goal of the assessment was to review, analyze, and synthesize available data and
information concerning the potential impacts of hydraulic fracturing on drinking water
resources in the United States, including identifying factors affecting the frequency or severity of
any potential impacts. In Chapter 1 of the assessment, are the goals, background, scope,
approach, and intended use of this assessment clearly articulated? In Chapters 2 and 3, are the
descriptions of hydraulic fracturing and drinking water resources clear and informative as
background material? Are there topics that should be added to Chapters 2 and 3 to provide
needed backgroundfor the assessment?
Chapters 1, 2, and 3 provide a generally well written overview of the assessment and descriptions of
hydraulic fracturing, the HFWC, and drinking water resources. However, Chapter 1 could be improved
by including and highlighting a concise statement of the goals of the assessment, and by incorporating a
more careful statement of its scope. The description of hydraulic fracturing in Chapter 2 is clear and
informative, but needs to give more emphasis to some aspects of hydraulic fracturing that distinguish it
from conventional water well and oil/gas well construction. The description of drinking water resources
in Chapter 3 is also clear and informative, but could be improved, in particular by paying more attention
to the local geology, hydrogeology, and to the physical properties (thickness, porosity, permeability,
fracture density) of the rock layers overlying target horizons, and including more discussion of the
characteristics and proximity of overlying water-supply aquifers.
As the intended users of the final Assessment Report range from policy makers and regulators to the
industry and the public, the EPA should include illustrative material (illustrations, diagrams, and charts)
in these chapters so that non-technical readers have visuals to facilitate understanding of the technical
material. Within Chapters 2 and/or 3, the final Assessment Report should also include discussions of
new hydraulic fracturing technologies. Within Chapter 1 or an appendix, the final Assessment Report
should include an overview discussion of federal, state and tribal standards and regulations that pertain
to hydraulic fracturing activities for oil and gas development, and mechanisms for enforcement of the
laws with respect to protection of surface water quality, groundwater quality, municipal water supplies,
and private wells. The overview should provide a description of organizations responsible for
monitoring and regulating HFWC activities.
The EPA should add more information regarding groundwater resources in hydraulically fractured areas
(e.g., typical depths to aquifers, confined or unconfined aquifers, and aquifer thicknesses). The final
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Assessment Report should present more information regarding the vertical distance between surface-
water bodies and the target zones being fractured and the depths of most existing and potential future
water-supply aquifers compared to the depths of most hydraulically fractured wells. In addition, in
regard to potential impacts on aquifers, the final Assessment Report should present more information
regarding situations where the vertical distance between the hydraulically fractured production zone and
a current or future drinking water source is relatively small depending on local hydrogeological
conditions. Differences in the fracturing morphology as a function of depth should also be discussed.
The final Assessment Report should include text to describe why the EPA assessed certain HF-related
topics and issues, while others (e.g., contamination from drilling fluids and cuttings) were considered to
be beyond the scope of the assessment.
It should be emphasized that the EPA-conducted research was integrated with a large amount of
additional information and research. The EPA should explicitly explain what it did in terms of its own
research in developing the assessment. The EPA should also discuss the temporal characteristics and
differences in temporal characteristics for the HFWC stages in Chapter 2 (e.g., the differences in
duration of the actual hydraulic fracturing of the rock versus the duration of production). In addition, the
EPA should assess whether there are specific local and regional aquifers that are particularly impacted
by hydraulic fracturing activities, and if so, provide quantifiable information on this topic within the
final Assessment Report.
Also, the section on site identification and well development in Chapter 2 should include some
discussion noting that the geological formations now being targeted for oil and gas production using
hydraulic fracturing and horizontal drilling require closer well spacing that, compared to conventional
drilling methods, may have greater potential impacts on drinking water resources. More discussion of
the potential impacts on drinking water resources, both positive and negative, of well densities and
multiple wells on one pad in unconventional oil and gas development should be included. In addition,
the EPA should recognize in Chapter 2 that some oil and gas resources being developed with the aid of
hydraulic fracturing are located in close proximity to large populations.
Water Acquisition Stage in the HFWC (Charge Question 2)
The scope of the assessment was defined by the HFWC, which includes a series of activities
involving water that support hydraulic fracturing. The first stage in the HFWC is water
acquisition: the withdrawal of ground or surface water neededfor hydraulic fracturing fluids.
This is addressed in Chapter 4.
a. Does the assessment accurately and clearly summarize the available information
concerning the sources and quantities of water used in hydraulic fracturing?
b. Are the quantities of water used and consumed in hydraulic fracturing accurately
characterized with respect to total water use and consumption at appropriate temporal
and spatial scales?
c. Are the major findings concerning water acquisition fully supported by the information
and data presented in the assessment? Do these major findings identify the potential
impacts to drinking water resources due to this stage of the HFWC? Are there other
major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible andfully supported?
d. Are the uncertainties, assumptions, and limitations concerning water acquisition fully
and clearly described?
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e. What additional information, background, or context should be added, or research gaps
should be assessed to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
An enormous amount of available information about the quantities of water used in hydraulic fracturing
was synthesized in Chapter 4 of the draft Assessment Report. The agency concludes Chapter 4 with a
statement that the quantity of water withdrawn for hydraulic fracturing represents a small proportion of
freshwater usage at regional or state-wide levels. While the draft Assessment Report comprehensively
summarizes available information concerning the sources and quantities of water used during HFWC
operations from surface water, groundwater, and treated wastewaters, the SAB finds that the EPA's
statistical extrapolation to describe average conditions at the national scale masks important regional and
local differences in water acquisition impacts. Many stresses to surface or groundwater resources
associated with water acquisition and hydraulic fracturing are often localized in space and temporary in
time but nevertheless can be important and significant.
The SAB concurs with the EPA's findings that water withdrawals for hydraulic fracturing are capable of
temporarily altering the flow regimes of streams, even in regions of rainfall abundance, and that the
potential for water availability impacts on drinking water resources is greatest in areas with high
hydraulic fracturing water use, low water availability, and frequent drought. While the SAB concurs
with these findings, within the final Assessment Report the agency should succinctly summarize the
regulatory, legal, management, and market frameworks in which the HFWC activities are managed that
aim to minimize the potential for these negative impacts. For example, the regulatory framework in
Pennsylvania that is discussed in the draft Assessment Report and its effects on managing water
withdrawal could be cited among the EPA's major findings.
The EPA should describe best management practices being implemented by the states or other
regulatory agencies (e.g., the Susquehanna River Basin Commission) that have well established
programs in permitting, collecting, monitoring and managing water resources as a longer-term future
activity. In the final Assessment Report the agency should describe the scale of the task for gathering
and organizing data collected by states, its efforts to investigate data available from state agencies, and
the critical lessons learned from the effort.
The SAB recommends that the EPA conduct further work to explore how hydraulic fracturing water
withdrawals affect short-term water availability at local scales. The EPA should enhance the
understanding of localized impacts by providing more focus and analysis on the Well File Review and
on examining other information not in literature and common databases to provide information about
actual hydraulic fracturing water acquisition and its relationship to drinking water.
The SAB is concerned that the EPA had planned to conduct, but did not conduct, prospective case
studies that contemplated drilling observation wells, collection of groundwater samples and other
monitoring before and during drilling, hydraulic fracturing and production operations. The goal for the
prospective studies was to follow the complete development of production wells, and to collect data
prior to, during, and after hydraulic fracturing at the sites. Such studies would allow EPA to carefully
evaluate changes in water quality over time: throughout drilling, injection of fracturing fluids, flowback,
and production.
The SAB finds that the datasets collected during planned prospective case studies would have benefited
the EPA's assessment in evaluating changes in water quality over time, if any, and assessing the fate and
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transport of potential constituent contaminants if a release was observed. The SAB finds that such
detailed data would enable the EPA to reduce current uncertainties and research gaps about the relation
between hydraulic fracturing water acquisition and drinking water. The SAB finds that the EPA should
evaluate lessons learned from its initial attempts and implementation challenges in developing the
prospective case studies, including how these lessons could inform design of future prospective case
studies.
There are several additional major findings that the EPA should identify within this chapter. First, it
should more clearly emphasize that many stresses on water resources are expected to be localized in
space and temporary in time but can be important and significant, and should not understate the potential
for localized problems associated with such stresses. Second, the final Assessment Report should
consider further exploring and describing how water acquisition and associated potential impacts on
lowered streamflow and water table drawdown could affect the availability and quality of drinking
water. Third, the EPA final Assessment Report should expand on the discussion of the evolution and
utilization of technologies that are being used to facilitate use and reuse of produced water and use of
other historically underutilized sources of water (e.g., seawater, brackish groundwater containing 3,000-
10,000 mg/L TDS, mine drainage, and treated wastewaters) that if used for hydraulic fracturing (or other
purposes) could reduce the impacts of water acquisition on drinking water sources.
Chemical Mixing Stage in the HFWC (Charge Question 3)
The second stage in the HFWC is chemical mixing: the mixing of water, chemicals, and proppant
on the well pad to create the hydraulic fracturing fluid. This is addressed in Chapter 5.
a. Does the assessment accurately and clearly summarize the available information
concerning the composition, volume, and management of the chemicals used to create
hydraulic fracturing fluids?
b. Are the major findings concerning chemical mixing fully supported by the information
and data presented in the assessment? Do these major findings identify the potential
impacts to drinking water resources due to this stage of the HFWC? Are there other
major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible andfully supported?
c. Are the uncertainties, assumptions, and limitations concerning chemical mixing fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
The chemical mixing stage of the HFWC, addressed in Chapter 5 of the draft Assessment Report,
includes a series of above-ground, engineered processes involving complex hydraulic fracturing fluid
pumping and mixing operations. The potential failure of these processes, including on-site and near-site
containment, poses a potentially significant risk to drinking water supplies. The SAB finds that the data
presented by the EPA within this chapter indicate that spills occur at hydraulic fracturing sites; that there
are varying causes, composition, frequency, volume, and severity of such spills; and that little is known
about certain hydraulic fracturing constituents and their safety. While the EPA conducted a large effort
in developing this chapter, all but one Panel member are concerned that two fundamental, underlying
questions have not been answered: (1) What is the potential that spills occurring during the chemical
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mixing process affect drinking water supplies? and (2) What are the relevant concerns associated with
the degree to which these spills impact drinking water supplies?
The SAB is also concerned that the EPA's major finding that: "None of the spills of hydraulic fracturing
fluid were reported to have reached groundwater" is supported only by an absence of evidence rather
than by evidence of absence of impact. The EPA should assess the likelihood of detecting an impact
given the current state of groundwater and surface water monitoring in the United States. If routine
monitoring systems are adequate to capture this impact if it occurred, then a lack of evidence of impact
may support a conclusion that there was no impact. If the routine monitoring systems would not be
expected to capture an impact that occurred, then a lack of evidence of impact may not support a
conclusion of no impact. The limitations of the data sources (e.g., FracFocus) appear to have led to an
incomplete record associated with the potential impacts associated with such spills. Further, there is a
lack of a critical assessment of the data presented in this chapter in a number of instances, and the SAB
concludes that the EPA needs to conduct such critical assessment to support conclusions that the EPA
may make on such data. One Panel member finds that the draft Assessment Report provided a thorough
description of the variables associated with a spill (i.e., amount, duration, soils, weather, groundwater,
surface water, constituents released, and other spill aspects), and noted that the Report should provide
more granularity on how states respond to spills.
There are two areas of uncertainty in this chapter of the draft Assessment Report that should be
described more clearly in the final Assessment Report:
(1) There is uncertainty regarding which hydraulic fracturing constituents have been used
globally and at any specific site; and
(2) There is uncertainty regarding the frequency, severity, and types of hydraulic fracturing-
related spills and their associated impacts.
To reduce these uncertainties, the EPA should make Chapter 5 more current by including more recent
available data, and conduct a more comprehensive and thorough analysis of the available data, on these
topics. Chapter 5, as it stands, provides little information on the magnitude of hydraulic fracturing spills
and it does not adequately describe either the uncertainty associated with the data or the lack of
understanding of such spills. The SAB notes that the EPA's estimates on the frequency of on-site spills
were based upon information from two states. While the SAB recognizes that the states of Pennsylvania
and Colorado likely have the most complete datasets on this topic that the EPA could access, the SAB
finds that the draft Assessment Report's analysis of spill data cannot be extrapolated across the entire
United States. The SAB also notes that subsurface conditions commonly vary within and between states
and this limits potential extrapolation of this dataset towards topics other than frequency of spills (e.g.,
while the geology may not have a large effect on the frequency or volume of a spill, the dataset could be
used to assess issues regarding the fate and potential impacts of spilled hydraulic fracturing constituents
in different geologies). The SAB encourages the agency to contact state agencies, review state databases
and update the final Assessment Report to reflect a broader analysis. While the SAB recognizes that
state database systems vary, the databases should be incorporated into the EPA's reporting of metrics
within the final Assessment Report.
The SAB recommends that the agency revisit a broader grouping of states and "refresh" the final
Assessment Report with updated information on the reporting of spills associated with HFWC activities.
The SAB finds that the reported uncertainties, assumptions, and limitations concerning chemical mixing
are not fully and clearly described, and that data limitations compromise the ability to develop
definitive, quantitative conclusions within the final Assessment Report regarding the frequency and
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severity of spilled liquids. The SAB also concludes that the retrospective case studies that are reported in
the draft Assessment Report do not provide sufficient clarity on: the potential severity of spilled liquids;
pre-existing conditions of groundwater; causation for the issue; whether related to specific HF activity,
and if so which aspect (e.g., well integrity); or current regulatory status with the relevant agencies
associated with the sites. The EPA provided incomplete data on chemical mixing process spill frequency
and the potential severity of effects of such spills on drinking water resources. The SAB finds that the
EPA's conclusion based on these limited data (i.e., that the risk to drinking water supplies from this
stage of the HFWC is not substantial) is not supported or linked to data presented in the body of the draft
Assessment Report. The EPA should revise its interpretation of these limited data.
The SAB recommends that the EPA revise its assessments associated with the chemical mixing stage of
the HFWC. To address these aforementioned concerns, the agency should:
• Revise Chapter 5 of the final Assessment Report to provide more information regarding the
extent or potential extent of the effects of spills associated with chemical mixing processes from
hydraulic fracturing operations on drinking water supplies.
• Define "severity" in a way that is amenable to quantitative analysis and clearly delineate those
factors contributing to spill severity.
• Describe the type of data needed to provide a meaningful assessment of the extent, severity and
potential impacts of spills. The assessment needs to be critical and based on the relevant factors
contributing to spill severity, including the mass of constituents spilled, the total volumes of the
spills, duration of the spills, and site geology.
• Describe clearly the efforts that the EPA made to use available data, and barriers, if any, that the
EPA encountered.
• Include within the final Assessment Report a more thorough presentation and explanation of the
frequency and types of data that the hydraulic fracturing industry reports, some of which may
not be readily accessible (i.e., not in an electronic format that is 'searchable').
• Provide improved analysis on the current state of data reporting on spills and the nature of
hydraulic fracturing fluids.
• Investigate at least one state as a detailed example for scrutinizing the available spill data (since
a number of states have spill reporting requirements and processes).
Well Injection Stage in the HFWC (Charge Question 4)
The third stage in the HFWC is well injection: the injection of hydraulic fracturing fluids into the
well to enhance oil and gas production from the geologic formation by creating new fractures
and dilating existing fractures. This is addressed in Chapter 6.
a. Does the assessment clearly and accurately summarize the available information
concerning well injection, including well construction and well integrity issues and the
movement of hydraulic fracturing fluids, and other materials in the subsurface?
b. Are the major findings concerning well injection fully supported by the information and
data presented in the assessment? Do these major findings identify the potential impacts
to drinking water resources due to this stage of the HFWC? Are there other major
findings that have not been brought forward? Are the factors affecting the frequency or
severity of any impacts described to the extent possible andfully supported?
c. Are the uncertainties, assumptions, and limitations concerning well injection fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
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resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
The well injection stage has an important role in the HFWC's potential influence on drinking water
resources. The chapter covers a wide range of topics and raises many potential issues regarding the
potential effects of hydraulic fracturing on drinking water resources. While Chapter 6 provides a
comprehensive overview of the well injection stage in the HFWC, the chapter is very densely written
and may not be accessible to the nontechnical reader. The SAB recommends that the EPA include
additional, clearer diagrams and illustrations in this chapter to help the reader better understand the
concepts and the most significant failure scenarios and mechanisms regarding this stage in the HFWC.
The EPA should also include discussions of new technologies and federal, state and tribal standards and
regulations intended to improve hydraulic fracturing operations.
Chapter 6 provides a comprehensive list of possible hydraulic fracturing-related failure scenarios and
mechanisms related to this stage in the HFWC. Before drawing conclusions on water quality impacts
associated with this HFWC stage, the agency should:
• More clearly describe the probability, risk, and relative significance of potential hydraulic
fracturing-related failure mechanisms, and the frequency of occurrence and most likely
magnitude and/or probability of risk of water quality impacts, associated with this stage in the
HFWC.
• Include a discussion of recent state hydraulic fracturing well design standards, required
mechanical integrity testing in wells, new technologies and fracture fluid mixes, and federal,
state and tribal regulatory standards that have changed, or may have changed, the probability of
risk of water quality impacts associated with this stage in the HFWC.
• Include an analysis and discussion on hydraulic fracturing case studies and example situations
where impacts may have occurred.
Important lessons from carbon capture and storage studies, such as those conducted under the U.S.
Department of Energy (DOE), have shown that well construction and integrity issues are a primary
concern with potential releases of constituents into the environment associated with subsurface storage.
The SAB notes that these carbon capture and storage studies have relevance to assessments regarding
potential releases from hydraulic fracturing activities. The SAB recommends that the agency examine
DOE data and reports on risks of geological storage of CO2 to water resources and include relevant
information in the Assessment Report.
In the descriptions of the interpretive models used to assess fracture propagation and fluid migration
introduced and discussed in this chapter, the EPA should clarify that the model results are not based on
construction of a rigorous, predictive model that has been verified by reproducing field measured values
of fluid pressure and as such the model results cannot be called "evidence." In the final Assessment
Report the EPA should clearly describe the limitations of interpretive models. The EPA should clarify
that the models provide possible outcomes that are limited by the assumptions made in design and
implementation of the model. Any reference to a model needs to state the assumptions/limitations of the
model. Predictive models need to be validated with actual field measurements/data before making
forward predictions of fracture propagation and fluid migration.
The final Assessment Report should include some discussion about the ongoing work associated with
induced seismicity in HFWC activities and potential impacts on drinking water resources associated
with hydraulic fracturing activity. Induced seismicity from well injection for hydraulic fracturing should
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be distinguished from induced seismicity associated with hydraulic fracturing wastewater disposal via
Class II deep well injection. Detailed discussion of induced seismicity from hydraulic fracturing-related
wastewater disposal and related federal, state and tribal regulatory response should be reserved for
Chapter 8 which is focused on hydraulic fracturing-related wastewater treatment and disposal. The
trends associated with such induced seismicity should also be discussed, including whether deep well
injection of hydraulic fracturing-related wastewater is being reduced because of regulatory changes
driven by public concerns about seismic activity and its associated costs, as recently occurred in
Oklahoma.
A key aspect associated with assessing impacts from HFWC operations on drinking water supplies is
well construction and operations that are protective of drinking water resources, location and
characterization of abandoned/orphaned oil and gas wells, and isolation of potable water from hydraulic
fracturing operations. The agency should recognize in the final Assessment Report that the following
activities are essential activities for the protection of drinking water resources during the well injection
stage of hydraulic fracturing operations: inspection, testing and monitoring of the tubing, tubing-casing
annulus and other casing annuli; and monitoring and testing of the potable groundwater through which
the tubing, tubing-casing annulus and other casing annuli pass.
The SAB also notes that the EPA can reduce uncertainties associated with hydraulic fracturing cement
and casing characterization by examining and assessing substantially more than the 327 well files
evaluated out of the approximately 24,000 well files referenced in the draft Assessment Report. The
SAB recommends that the EPA conduct full statistical analyses on such an expanded Well File Review,
communicate more fully the statistical analyses that were conducted, and develop graphs or tables
associated with such analyses. The recommendations in this paragraph can be considered longer-term
future activities.
The SAB recommends that when estimated percentages are quoted from the Well File Review, the EPA
should accompany them with the relevant confidence intervals, and indicate whether they are found in
the text of the Well File Review or are inferred from graphs. The EPA should also discuss whether the
relatively low percentage of horizontal well completions covered by the Well File Review limits its
relevance to current practice.
The agency should include additional major findings associated with the higher likelihood of impacts to
drinking water resources associated with hydraulic fracturing well construction, well integrity, and well
injection problems. These findings should discuss factors and effects regarding the severity and
frequency of potential impacts from poor cementation techniques, hydraulic fracturing operator error,
migration of hydraulic fracturing constituents from the deep subsurface, and abandoned/orphaned oil
and gas wells.
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Flowback and Produced Water Stage in the HFWC (Charge Question 5)
The fourth stage in the HFWC focuses on flowback and produced water: the return of injected
fluid and water producedfrom the formation to the surface and subsequent transport for reuse,
treatment, or disposal. This is addressed in Chapter 7.
a. Does the assessment clearly and accurately summarize the available information
concerning the composition, volume, and management offlowback and produced waters?
b. Are the major findings concerning flowback and produced water fully supported by the
information and data presented in the assessment? Do these major findings identify the
potential impacts to drinking water resources due to this stage of the HFWC? Are there
other major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible andfully supported?
c. Are the uncertainties, assumptions, and limitations concerning flowback and produced
water fully and clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
Overall, the discussion on hydraulic fracturing flowback and produced water within Chapter 7 provides
a clear and accurate summary of the available information concerning composition, volume, and
management of flowback and produced waters. The chapter also provides an overview of fate and
transport of spilled liquids and the various components necessary to evaluate migration of a spill (i.e.,
amount of material released, timing of the release, response efforts, timing of response measures, soils,
geology, and receptors).
The EPA should provide additional detail on the extent and duration of the impacts of spilled liquids and
releases of flowback and produced waters when they occur, and conduct various activities including
those described below to reduce uncertainties associated with conclusions regarding such impacts:
• While Chapter 7 summarizes many types of incidents regarding the management of flowback
and produced waters and refers to case studies that describe leaks and spills, the chapter should
provide additional detail on the extent and duration of the impacts associated with these
incidents, including details on the impact of spilled liquids and releases when they occur. In
Chapter 7, the agency should quantify in text and in a figure the frequency of the different types
of release events, including whether the spilled material impacts groundwater or surface water, to
understand the likely probability of these events.
• While the major findings on hydraulic fracturing flowback and produced water presented in
Section 10.1.4 of the draft Assessment Report are supported by the analysis presented in Chapter
7, the major findings should be more explicitly quantified and clearly identified within Chapter
7.
• The agency should also include additional major findings associated with the effects on drinking
water resources of large spill events that escape containment, and sustained, undetected leaks.
• The final Assessment Report should discuss what is known about the fate of un-recovered
fracture fluids that are injected into hydraulically fractured wells, and where these fluids go if
they do not come back to the surface. The EPA should describe the challenge of monitoring and
modeling the fate of injected fracture fluids over time.
• Chapter 7 emphasizes the horizontal and vertical distance between spill and receptor without
adequately indicating that certain subsurface geologic conditions and hydraulic gradient
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scenarios in the shallow subsurface can allow spilled liquids to migrate a considerable distance
from the point of release. The final Assessment Report should describe the frequency and
severity of such events and recognize that such events could occur.
• While data gaps have been identified in Chapter 7, especially with respect to baseline conditions
and individual incidents, the final Assessment Report should clarify whether there are data gaps
because the data are non-existent or just not easily (i.e., electronically) available.
• The final Assessment Report should also include additional analysis and discussion on how
recycled hydraulic fracturing produced water that is reused onsite at hydraulic fracturing
facilities without treatment might affect the severity or frequency of potential contamination of
surrounding drinking water resources, in the event of a spill or release.
• The EPA should expand and clarify the discussion provided in Chapter 7 on the current use by
industry of tracers for injection fluids, as well as any efforts made by the EPA or other
researchers to develop tracers, and describe how the use of tracers might be an approach that
could allow assessment of releases of contamination and interpretation of the source of
contamination if it occurs. For example, the agency should summarize what constituents, metal
cations, and isotopes are used currently for chemical and radioactive tracers, the degree to which
tracers are used, where tracers are used, what concentrations are in use, and what concentrations
are measured for these tracers in flowback or produced waters.
• Regarding constituents of concern in flowback and produced waters:
o The agency should clarify whether constituents identified as being of most concern in
produced water are products of the hydraulic fracturing activity, flowback, or later-stage
produced water, or are constituents of concern derived from oil and gas production
activities that are not unique to hydraulic fracturing activity. These efforts may require
the development of analytical methods, which can be considered a recommendation for
longer-term future research activity,
o The SAB recommends that the EPA, in collaboration with state agencies, outline a plan
for analyzing organic constituents in HF flowback and produced waters since data on
flowback water composition are limited and the majority of the available data are for
inorganics. In addition, the EPA should evaluate as a longer-term future activity the
potential for using non-targeted chemical analysis to identify currently unmonitored HF
constituents.
o The agency should present additional information in Chapter 7 on changes in flowback
and produced waters chemistry over time,
o The agency should include more information and discussion in Chapter 7 regarding
radionuclides associated with hydraulic fracturing flowback and produced water
(including the Pennsylvania Department of Environmental Protection research on this
topic), bromide concentrations in hydraulic fracturing flowback and produced water and
wastes and in surface waters, and the natural occurrence of brines in the subsurface,
o The agency should develop a summary of best management practices for hydraulic
fracturing surface impoundments as a longer-term future activity.
The final Assessment Report should also include a discussion on the importance of background and
preexisting chemistry of surface and groundwater in developing a better understanding of whether
impacts from drilling and completion activities can be identified. A major public concern is the
appearance of contaminated (e.g., chemical constituents introduced into the water through HFWC
activities) or degraded (e.g., adverse changes in water quality associated with naturally occurring
chemicals influenced by HFWC activities) drinking water in wells in areas where hydraulic fracturing
occurs. Since naturally occurring contaminants and degraded drinking water in wells can occur from
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issues not related to hydraulic fracturing, the EPA should also include additional discussion on how
background and pre-existing baseline chemistry of surface and groundwater data are used to better
understand the impacts of hydraulic fracturing-related spills and leaks. The scientific complexity of
baseline sampling and data interpretation should be clearly and concisely described. Although baseline
sampling is simple in concept, it can be very difficult to obtain meaningful results in practice.
Concentrations of naturally occurring contaminants, including methane, aromatic hydrocarbons,
radionuclides, and disinfection by-product precursors, can vary significantly, both temporally and
spatially, especially in surface water and in groundwater drawn from shallow and/or alluvial
wells. Water quality can be significantly influenced by hydrological events (rainfall, flooding, drought),
by water acquisition for purposes other than hydraulic fracturing, and by spills or discharges or
constituents not associated with hydraulic fracturing. Obtaining representative samples, characterizing
natural variations in water quality, properly collecting (and preserving and storing) samples for the
analytes of interest, accurately determining the concentrations of the analytes of interest, and correctly
interpreting the data can be challenging tasks. In addition, the analysis of water chemistry data from
private wells requires the water chemistry data to be integrated with water-level data and details about
the construction and maintenance history of each well.
Wastewater Treatment and Waste Disposal Stage in the HFWC (Charge Question 6)
The fifth stage in the HFWC focuses on wastewater treatment and waste disposal: the reuse,
treatment and release, or disposal of wastewater generated at the well pad. This is addressed in
Chapter 8.
a. Does the assessment clearly and accurately summarize the available information
concerning hydraulic fracturing wastewater management, treatment, and disposal?
b. Are the major findings concerning wastewater treatment and disposal fully supported by
the information and data presented in the assessment? Do these major findings identify
the potential impacts to drinking water resources due to this stage of the HFWC? Are
there other major findings that have not been brought forward? Are the factors affecting
the frequency or severity of any impacts described to the extent possible andfully
supported?
c. Are the uncertainties, assumptions, and limitations concerning wastewater treatment and
waste disposal fully and clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
Overall, Chapter 8 clearly and accurately summarizes a large amount of existing information on the
rapidly evolving topic of treatment, reuse, and disposal of wastewater associated with hydraulic
fracturing, and recognizes the significant data and information gaps associated with this stage of the
HFWC. The chapter's summary of water quality characteristics of hydraulic fracturing-related
wastewaters from various sites states in several locations that spills or discharges of inadequately treated
wastewater from HFWC operations could result in significant adverse impacts on drinking water quality.
While Chapter 8 adequately summarizes many aspects related to hydraulic fracturing wastewater
treatment based upon literature analysis, it provides little in the way of new or original findings - such
as those anticipated based on the EPA's November 2011 final Hydraulic Fracturing Research Study Plan
(U.S. EPA 2011), and has other limitations. The chapter does not adequately address the potential
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frequency and severity of impacts of hydraulic fracturing wastewaters on drinking water quality, nor
potential scenarios in the near future that could influence such impacts (e.g., reduced access to deep well
injection due to restrictions associated with seismic activity). In addition, major findings concerning
hydraulic fracturing-related wastewater treatment and disposal, including the conclusion in the chapter
that "there is no evidence that these contaminants have affected drinking water facilities, " are not fully
supported by the information and data presented in Chapter 8, and also are not supported by peer
reviewed literature that has demonstrated contaminants from oil and gas wastewater disposal facilities
have reached drinking water facilities and have had effects (e.g., see States et al. 2013, which is cited in
the draft Assessment Report; and Landis et al. 2016). The agency should clearly and accurately describe
the basis for this statement in Chapter 8.
Chapter 8 of the draft Assessment Report also did not bring forward all the major findings associated
with the wastewater treatment and waste disposal phase of the HFWC. The draft Assessment Report
does not mention that elevated radionuclide concentrations are likely to be present in the effluents from
some CWTFs and most POTWs treating hydraulic fracturing-related wastewaters. The SAB also
recommends that the EPA include an assessment of the potential accumulation of radium in pipe scales,
sediments, and residuals; the potential for leaching of this radium into drinking water resources; and the
potential impacts of such leaching.
To address the above-noted concerns, the EPA should conduct further analyses including the following
listed activities. The SAB recommends that these activities be addressed in the final Assessment Report.
However, to avoid undue delay in publishing the final Assessment Report, the SAB recommends that
the activities that cannot be promptly addressed without further study should be identified in the final
Assessment Report as research that needs to be addressed as a longer-term future activity:
• The final Assessment Report should more clearly describe the potential frequency and severity
of impacts associated with this stage in the HFWC, before drawing conclusions on water quality
impacts associated with this HFWC stage.
• The chapter describes unit processes and treatment technologies used in both CWTFs and other
treatment facilities (e.g., on-site and at POTWs), but many of these descriptions are very general
and sometimes incorrectly describe such unit processes; the chapter needs to be revised to
address this issue.
• The agency should further assess impacts on public drinking water supplies that rely upon
surface water intakes downstream of hydraulic fracturing activities or discharges of hydraulic
fracturing fluids. To assess this topic, a variety of information is needed including: the size and
location of injection wells, CWTFs and POTWs receiving wastewater discharges (directly or
indirectly); the locations and treatment capabilities of drinking water treatment facilities; and the
locations of streams and lakes and their flowrates and volumes, respectively. There are relatively
few CWTFs known to be discharging to surface waters or POTWs, and the EPA should provide
information on the contributions that CWTFs may make to TDS, regulated contaminants, and
other contaminants of concern in downstream public water supplies. The EPA should also
provide similar information for any POTWs known to be accepting wastewater associated with
hydraulic fracturing.
• The chapter should clearly summarize the regulatory framework around CWTFs and POTWs
receiving wastewater discharges associated with hydraulic fracturing-related oil and gas
production.
• While the chapter notes that treated hydraulic fracturing wastewater discharges can increase
formation of brominated and iodinated disinfection by-products (DBPs) at downstream drinking
water treatment plants, the agency should also discuss in Chapter 8 other DBPs that could form
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at downstream water treatment plants (and water resource reclamation facilities) impacted by
wastewater discharges associated with hydraulic fracturing.
• The agency should clearly and accurately summarize in Chapter 8 available information
regarding the impacts of water recycling on pollutant concentrations and their potential impacts
on drinking water quality should spills of recycled water occur.
• The agency should revise Chapter 8 in the draft Assessment Report to adequately describe the
composition and disposal methods of residuals from CWTFs (including residuals from zero-
liquid discharge facilities), and whether and to what extent those residuals may impact drinking
water sources now and in the future.
• The agency should further consider, in Chapter 8: temporal trends for costs of hydraulic
fracturing water purification technologies over the past decade; trends in hydraulic fracturing-
related wastewater disposal methods including the scientific, regulatory and economic drivers of
these changes and their potential impacts on drinking water resources; and potential future
trajectories associated with these trends (e.g., if deep well injection of hydraulic fracturing-
related wastewater is being reduced because of regulatory changes driven by public concerns
about seismic activity and its associated costs).
• The SAB finds that the chapter does not adequately assess other waste disposal issues such as:
(1) disposal of cuttings and drilling muds and disposal of residuals from drinking water treatment
plants and POTWs impacted by wastewater discharges associated with hydraulic fracturing; and
(2) disposal of soils, pond sediments, and other solid media contaminated by hydraulic fracturing
constituents. The chapter should be revised to include some level of assessment on these topics,
and to outline data gaps that should be addressed in longer-term future activity.
• The agency should also describe, in Chapter 8, the potential impacts of induced seismicity
(associated with and likely caused by hydraulic fracturing wastewater disposal activity) on water
quality and drinking water resources, and on oil and gas production and public water supply
infrastructure (e.g., damage to wells and storage vessels, and also to pipelines transporting
hydraulic fracturing-related water and wastewater).
• The final Assessment Report should further describe that technologically-enhanced naturally
occurring radioactive materials (TENORM) may pose a significant risk since treatment processes
used to remove other constituents (such as metals, biochemical oxygen demand, or TDS) from
hydraulic fracturing wastewaters may not remove radionuclides to levels that are protective of
public health. The frequency and severity of impacts associated with strontium in hydraulic
fracturing wastewaters should also be acknowledged in the final Assessment Report.
• The final Assessment Report should include analyses on the potential for hydraulic fracturing
wastewaters to form nitrosamines (e.g., N-Nitrosodimethylamine, NDMA,) and describe the
potentially significant impacts of nitrosamine formation within hydraulic fracturing wastewater
discharges on drinking water resources.
Chemicals Used or Present in Hydraulic Fracturing Fluids (Charge Question 7)
The assessment used available information and data to identify chemicals used in hydraulic
fracturing fluids and/or present in flow back and produced waters. Known physicochemical and
toxicological properties of those chemicals were compiled and summarized. This is addressed in
Chapter 9.
a. Does the assessment present a clear and accurate characterization of the available
chemical and toxicological information concerning chemicals used in hydraulic
fracturing?
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b. Does the assessment clearly identify and describe the constituents of concern that
potentially impact drinking water resources?
c. Are the major findings fully supported by the information and data presented in the
assessment? Are there other major findings that have not been brought forward? Are the
factors affecting the frequency or severity of any impacts described to the extent possible
andfully supported?
d. Are the uncertainties, assumptions, and limitations concerning chemical and
toxicological properties fully and clearly described?
e. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize chemical and toxicological information in this
assessment? Are there relevant literature or data sources that should be added in this
section of the report?
The EPA clearly articulates its approach for characterizing the available physicochemical and
toxicological information. However, Chapter 9 of the draft Assessment Report should characterize
toxicological information on constituents employed in hydraulic fracturing in an inclusive manner, and
not restrict the criteria for selection of hydraulic fracturing constituents of concern to solely constituents
that have noncancer oral reference values (RfVs) and cancer oral slope factors (OSFs) that were peer
reviewed only by a governmental or intergovernmental source. The agency should use a broad range of
toxicity data, including information pertinent to subchronic exposures from a number of reliable sources,
in expanding the criteria for hydraulic fracturing constituents of concern. As the EPA broadens inclusion
of toxicological information to populate missing toxicity data, the EPA can expand the tiered hierarchy
of data described in the EPA report to give higher priority to constituents with RfVs without excluding
other quality toxicological information that is useful for hazard and risk assessment purposes.
The final Assessment Report should explicitly indicate what fraction of the constituents identified in
hydraulic fracturing fluid and/or produced waters have some hazard information (e.g., toxicity data
available from or used by the U.S. federal government, state governments, or international non-
governmental organizations, for risk assessment purposes, or publicly available peer-reviewed data), and
what fraction have no available information. In addition, the EPA should summarize potential hazards
from methane (physical hazard), bromide and/or chloride-related disinfection by-products formed in
drinking water, and naturally occurring constituents and other constituents (e.g., metals, radionuclides)
in hydraulic fracturing wastewater that were discussed in earlier chapters. An important limitation of the
EPA's hazard evaluation of constituents across the HFWC is the agency's lack of analysis of most likely
exposure scenarios and hazards associated with hydraulic fracturing activities. To help prioritize future
research and risk assessment efforts, the agency should identify within the final Assessment Report the
most important/likely exposure scenarios (durations and routes) and hazards (constituents) and obtain
toxicity information relevant to those exposure scenarios.
The EPA uses FracFocus 1.0 as the primary source of information on the identity and frequency of use
of constituents in hydraulic fracturing processes. The SAB expresses concern that the FracFocus
database may not be sufficient because it does not include certain confidential business information
(CBI) which is proprietary, and lacks information on the identity, properties, and frequency of use for
approximately 11% of hydraulic fracturing constituents used in HF operations (see EPA draft
Assessment Report, p. 5-73). Although the agency acknowledged limitations of the FracFocus data, the
EPA can do more to address them by characterizing in some way the toxicology data on proprietary
constituents that the EPA may have, and by using information provided in updated versions of
FracFocus on chemical class, type, mass and concentration (i.e., concentration of the constituent, in
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terms of % by mass, in the hydraulic fracturing fluid). Based on this information, the agency should
assess and clearly describe how gaps in knowledge about proprietary constituents affect the uncertainty
regarding conclusions that can be drawn on potential impacts of hydraulic fracturing on drinking water
resources. Since the FracFocus data that the agency assessed were current up to February 2013, the SAB
also recommends that the final Assessment Report discuss the current status, use and changes to the
FracFocus platform, and outline what follow-on analyses should be done with the FracFocus database.
As feasible, the EPA should consider conducting some preliminary analyses of trends as part of the final
Assessment Report. For example, analyses on trends in green chemical usage in HF could be conducted.
Further, the EPA should articulate needs for information that is collected and available from individual
states and that could help with assessment yet is not readily accessible. In addition, the agency should
note that the current version of FracFocus also provides some additional insights into the CBI associated
with constituents used during HF operations (for example, chemical type and categories).
Absent additional information, it is not feasible to conclude which constituents—each differing in
occurrence, concentration, and volume during the various phases of hydraulic fracturing gas and oil
extraction—are of greatest concern. While additional field studies should be given a high priority to
better understand the intensity and duration of exposures to constituents of flowback and produced
water, the SAB recommends this as a longer-term future activity.
In Chapter 9, the EPA presents a MCDA approach that the EPA conceived, designed and formulated as
a logical approach for assessing the scope and potential impacts of hydraulic fracturing on national
drinking water resources given that the information used is limited and fragmented (e.g., concentration,
volume and duration in different parts of the water cycle.) While the SAB agrees in principle that
toxicological and physicochemical information could approximate hazard potential under certain
exposure scenarios, the SAB does not agree with specific elements of, and limited selection of data
illustrating, the MCDA approach. The MCDA outlined by the EPA gives equal weight to information on
physicochemical scores, occurrence and toxicity. This may place undue emphasis on physicochemical
score. While useful in judging a constituent's likelihood of occurrence in drinking water, this value may
be a relatively poor surrogate for actual exposure. As an example, constituents may not be addressed that
tend to remain at their original deposition site and serve as a reservoir for prolonged release. In light of
the limitations described above and in the SAB's response to Charge Question 7a (e.g., the EPA limited
toxicological information to government reviewed reference values), and given that the EPA applied this
approach to only 37 constituents used in hydraulic fracturing fluids and 23 constituents detected in
flowback or produced water, the EPA's MCDA results should be considered for preliminary hazard
evaluation purposes only, as the EPA originally intended. In addition, the agency should suggest use of
an MCDA approach on a regional or site-specific basis where more complete constituent identity,
concentrations and toxicity information is available for the specific case being analyzed.
For clarity, the final Assessment Report should distinguish between constituents injected into a
hydraulic fracturing well vs. constituents and hydrocarbons that come out of the well in produced fluids.
The SAB suggests that if no constituents are added to a hydraulically fractured well, there is still a
potential for impacts to drinking water resources from constituents present naturally in the subsurface
which could also be brought to the surface in produced water. In Chapter 9 and throughout the draft
Assessment Report, constituents and potential impacts unique to hydraulic fracturing oil and gas
extraction should be clearly distinguished from those that also exist as a component of conventional oil
and gas development. The agency should clarify whether constituents identified as being of most
concern in produced water are products of the hydraulic fracturing activity, flowback, or later-stage
produced water, or are constituents of concern derived from oil and gas production activities that are not
unique to hydraulic fracturing activity. These efforts may require the development of analytical
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methods, which can be considered a recommendation for longer-term future research activity. Such
activities will help inform the readers about the different characteristics of HF flowback and produced
waters and in-situ groundwater constituents relative to formation water produced in conventional oil and
gas development.
Synthesis of Science on Potential Impacts of Hydraulic Fracturing on Drinking Water Resources, and
Executive Summary (Charge Question 8)
The Executive Summary and Chapter 10 provide a synthesis of the information in this assessment. In
particular, the Executive Summary was written for a broad audience.
a. Are the Executive Summary and Chapter 10 clearly written and logically organized?
b. Does the Executive Summary clearly, concisely, and accurately describe the major findings
of the assessment for a broad audience, consistent with the body of the report?
c. In Chapter 10, have interrelationships and major findings for the major stages of the HFWC
been adequately explored and identified? Are there other major findings that have not been
brought forward?
d. Are there sections in Chapter 10 that should be expanded? Or additional information added?
The EPA should significantly modify the form and content of the Executive Summary and Chapter 10
Synthesis of the draft Assessment Report. The Executive Summary is unlikely to be understandable by a
large segment of its readership, and should be revised to make this section more suitable for a broad
audience. Clearer statements are needed on the goals and scope of the assessment and on specific
descriptions of hydraulic fracturing activities, and additional diagrams and illustrations should be
provided to enhance the public's understanding of hydraulic fracturing activities and operations.
Technical terms should be used sparingly and should always be defined, and graphics should be
introduced to illustrate and clarify key concepts and processes.
Several major findings presented in both the Executive Summary and Chapter 10 Synthesis were
discussed at length by the SAB Panel. The SAB finds that several major findings are ambiguous and
require clarification, and/or are inconsistent with observations presented in the body of the draft
Assessment Report. These major findings include:
• "We did not find evidence that these mechanisms have led to widespread, systemic impacts on
drinking water resources in the United States(on page ES-6).
• "High fracturing water use or consumption alone does not necessarily result in impacts to
drinking water resources(on page ES-9, lines 19-20).
• "None of the spills of hydraulic fracturing fluid were reported to have reached groundwater. "
(on pages ES-13 and 10-8)
• "The number of identified cases, however, was small compared to the number of hydraulically
fractured wells'' (on page ES 6).
• "According to the data examined, the overall frequency of occurrence [of hydraulically fractured
geologic units that also serve as a drinking water sources] appears to be low. " (on page ES-15,
lines 34-35).
• "Chronic releases can and do occur from produced water stored in unlined pits or
impoundments, and can have long-term impacts." (on page ES-19, lines 18-19).
The SAB is concerned that these major findings do not clearly, concisely, and accurately describe the
findings developed in the chapters of the draft Assessment Report, and that the EPA has not adequately
supported these major findings with data or analysis from within the body of the draft Assessment
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Report. Four Panel members concluded that the major finding described above under the first bullet is
clear as written.
The agency should strengthen the Executive Summary and Chapter 10 Synthesis by linking the stated
findings more directly to evidence presented in the body of the draft Assessment Report. The EPA
should more precisely describe each of the major findings of the final Assessment Report in both the
Executive Summary and Chapter 10 Synthesis, including specific cases of drinking water impacts, that
relate to these major findings.
The agency should revise the synthesis discussion in Chapter 10 to present integrated conclusions, rather
than a summary of findings from Chapters 4-9. The agency should also revise Chapter 10 to discuss
methods to reduce uncertainties related to the HFWC, including ongoing research, and data and research
needs.
The Executive Summary focuses on national- and regional-level generalizations of the potential effects
of hydraulic fracturing-related activities on drinking water resources. Although these generalizations are
often desirable and useful, the EPA should make these conclusions cautiously, and clearly qualify these
conclusions through acknowledgement of the substantial heterogeneity existing in both natural and
engineered systems. Furthermore, the EPA should provide more emphasis in the Executive Summary on
the importance of local hydraulic fracturing potential impacts. These local-level impacts may occur
infrequently, but they have the potential to be severe and the Executive Summary should more clearly
describe such impacts. Further, the locally important impacts are unlikely to be captured in a national
level summary of impacts.
The final Assessment Report should also identify ongoing research and needs for future research,
assessment and field studies. The SAB recommends that the EPA include in that discussion the EPA's
future plans for conducting prospective studies and other research that the EPA had planned to conduct
but did not conduct or complete.
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2. INTRODUCTION
2.1. Background
In its Fiscal Year 2010 Appropriation Conference Committee Directive to the EPA, the U.S. House of
Representatives urged the agency 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.
Hydraulic fracturing (HF) is a well stimulation technique used by oil and gas producers to explore and
produce natural gas and oil from sources such as coalbed methane and shale formations. The extraction
process includes: site exploration, selection and preparation; equipment mobilization-demobilization;
well construction and development; mixing and injecting fracturing fluids; hydraulic fracturing of the
formation; produced water and waste management, transport, treatment, and/or disposal; gas production
(infrastructure for storage and transportation); and site closure.
In June 2015, the EPA's Office of Research and Development (ORD) released a draft assessment report
(U.S. EPA 2015a), entitled Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas
on Drinking Water Resources. ORD requested the EPA SAB conduct a peer review of the EPA's draft
Assessment report and respond to specific charge questions.
The draft Assessment Report synthesizes available scientific literature and data on the potential that
hydraulic fracturing for oil and gas production may change the quality or quantity of drinking water
resources, and identifies factors affecting the frequency or severity of any potential changes. The draft
Assessment Report follows the hydraulic fracturing water cycle (HFWC) described in the Study Plan
(U.S. EPA 2011) and Progress Report (U.S. EPA 2012). The HFWC includes five stages: (1) water
acquisition for hydraulic fracturing fluids; (2) chemical mixing to form fracturing fluids; (3) well
injection of fracturing fluids; (4) flowback and produced water; and (5) wastewater treatment and
disposal. Potential impacts on drinking water resources are considered at each stage in this cycle.
2.2. SAB Review Process
In response to the U.S. Congress, the EPA developed a study scope for the HF study (U.S. EPA 2010)
that was reviewed by the SAB Environmental Engineering Committee and additional members of the
SAB in an open meeting on April 7-8, 2010. The SAB's report on its review of the study scope was
provided to the Administrator in June 2010. In its response to the EPA in June 2010, the SAB endorsed
a lifecycle approach for the research 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 (SAB 2010).
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EPA then developed a research Study Plan (U.S. EPA 2011) that was reviewed by the SAB Panel in an
open meeting on March 7-8, 2011. In its response to the EPA in August 2011, the SAB found the EPA's
approach for the research Study Plan to be appropriate and comprehensive, and concluded that the EPA
has identified the necessary tools in its overall research approach to assess impacts of hydraulic
fracturing on drinking water resources (SAB 2011). The EPA's research Study Plan identified specific
potential outcomes for the research related to each step in the HFWC, and the SAB did not anticipate
that all of these outcomes could be achieved given the time and cost constraints of the proposed research
program. Further, the SAB identified several areas of the research Study Plan that could be better
focused and suggested several additional topics for further study.
In late 2012, the EPA released a Progress Report (U.S. EPA 2012) on the study detailing the EPA's
research approaches and next steps. The SAB Hydraulic Fracturing Research Advisory Panel held a
consultation with agency staff in an open meeting on May 7-8, 2013. At the May 2013 consultation
meeting, ORD briefed the SAB Panel on the current status of its research, and the Panel members
individually addressed 12 charge questions spanning each of the five components of the hydraulic
fracturing lifecycle, including water acquisition, chemical mixing, well injection, flowback and
produced water, and wastewater treatment and waste disposal. Members discussed the charge questions
and also developed individual written responses which were posted on the SAB May 2013 meeting
webpage.
On June 4, 2015, ORD released its draft Assessment Report and requested the SAB to conduct a peer
review on the draft Assessment Report. On September 30, 2015, the SAB Panel conducted a public
teleconference to receive a briefing on the EPA's draft Assessment Report and to discuss the EPA's
charge questions. On October 28-30, 2015, the SAB Panel conducted an advisory meeting to develop
consensus advice in response to charge questions associated with the research described in the EPA's
draft Assessment Report. The charge questions are listed at the beginning of each section below and in
Appendix A.
The SAB Panel held a public teleconference call on December 3, 2015 to complete agenda items from
the October 28-30, 2015 SAB Panel meeting and further develop preliminary key points in response to
charge questions on the agency's draft assessment. The SAB Panel then held public teleconferences on
February 1, February 2, March 7 and March 10, 2016, to discuss substantive comments from Panel
members on this draft SAB report. At a public meeting on June 14, 2016, the chartered SAB deliberated
on the SAB Panel's draft report and agreed that chair and the lead reviewers on the chartered SAB
would work with the chair of the SAB Panel to revise the draft SAB report in accordance with
discussions at the June 14, 2016 public meeting.
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3. RESPONSES TO THE EPA'S CHARGE QUESTIONS
3.1. Goals, Background and History of the Assessment
Question 1: The goal of the assessment was to review, analyze, and synthesize available data and
information concerning the potential impacts of hydraulic fracturing on drinking water resources in the
United States, including identifying factors affecting the frequency or severity of any potential impacts.
In Chapter 1 of the assessment, are the goals, background, scope, approach, and intended use of this
assessment clearly articulated? In Chapters 2 and 3, are the descriptions of hydraulic fracturing and
drinking water resources clear and informative as background material? Are there topics that should be
added to Chapters 2 and 3 to provide needed background for the assessment?
Chapter 1 provides an introductory section and a discussion on the background, scope, approach and
organization of the draft Assessment Report. Chapter 2 provides a discussion on hydraulic fracturing, oil
and gas production, and the U.S. energy sector. It defines hydraulic fracturing, discusses how
widespread hydraulic fracturing is, and describes the trends and outlook for the future of hydraulic
fracturing. Chapter 3 describes drinking water resources in the United States, and discusses current and
future drinking water resources and the proximity of drinking water resources to hydraulic fracturing
activity.
3.1.1. Goals and Scope of the Assessment
In Chapter 1 of the assessment, are the goals, background, scope, approach, and intended use of this
assessment clearly articulated?
Chapter 1 is well written, and introduces the background and intended use of the assessment clearly and
understandably. However, it needs a clear and explicit statement of the goals and objectives of the
assessment to provide a coherent framework for the entire document. Chapter 1 also needs to better
distinguish the goals from the approach. For instance, the review, synthesis, and analysis of scientific
literature and information provided by stakeholders, and of research conducted, should be stated as part
of the approach rather than a goal of the study.
It should be emphasized that the EPA-conducted research was integrated with a large amount of
additional information and research. The EPA should be explicit about how its own research was used in
developing the assessment. The use of the EPA-sponsored research projects, technical input from
agencies, industries, Non-Governmental Organizations (NGOs) and other stakeholders should be
highlighted as part of the approach.
As stated on page 1-2 of the draft Assessment Report, the scope of the assessment is "defined by the
HFWC" and it is desirably broad, in particular not limiting it solely to the actual hydraulic fracturing
step. The final Assessment Report should provide additional explanation of the rationale for the
agency's choice to use the HFWC to assess impacts of hydraulic fracturing on drinking water resources.
The EPA should discuss in the final Assessment Report all of the ways in which hydraulic fracturing
and related activities might impact the quality or quantity of drinking water resources in one of the five
HFWC stages. The EPA should include text to describe why the EPA assessed certain HF-related topics
and issues within the final Assessment Report, while others (e.g., contamination from drilling fluids and
cuttings) were considered to be beyond the scope of this assessment. Also, the EPA should consistently
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revise text throughout the final Assessment Report when referring to hydraulic fracturing to note that the
EPA is referring to the entire HFWC, consisting of the five stages defined in the assessment.
As noted in Chapter 1, the definition of the study scope was broad but not all inclusive, and some
aspects of oil and gas production are stated to be outside the scope of the draft Assessment Report.
However, the statement in Chapter 1 about aspects of the draft Assessment Report that are outside the
scope of the assessment is not entirely consistent with the rest of the draft Assessment Report. For
example, hydraulic fracturing well closure is explicitly excluded in Chapter 1, and yet Chapter 2
contains a section on "Site and Well Closure." Also, hydraulic fracturing imposes unique stresses on
well structure, such as casing and cement, and hence well integrity, even post production, is within the
scope (e.g., concerns about the integrity of inactive or orphaned wells are discussed in Chapter 6). The
EPA should revise statements in Chapter 1 to include situations and analyses that are discussed later in
the draft Assessment Report, or if appropriate to the draft Assessment Report's goals, exclude them
from later discussion.
The intended users of the final Assessment Report range from policy makers and regulators to the
industry and the public; however, parts of Chapters 1 to 3 are overly technical for many of those users.
The technical details are important, and should not be diluted. The EPA should include illustrative
material (illustrations, diagrams, and charts) in these chapters so that non-technical readers have visuals
to facilitate understanding of the technical material. Where appropriate, the EPA should move some
technical details to an appendix of the final Assessment Report, replaced by graphical material. The
SAB recognizes that many readers of the final Assessment Report will read only the Introduction and
Executive Summary, and thus recommends that the EPA should not put all such details in appendices.
Considerable public interest associated with hydraulic fracturing and the HFWC in general is generated
by experiences at individual sites. In Chapter 1, the agency should acknowledge the importance of these
experiences, and the needs associated with public outreach and education related to drinking water
quality.
In Chapter 1, the agency should provide a general overview discussion of the relevant federal, state and
tribal laws and requirements pertaining to hydraulic fracturing activities for oil and gas development,
and mechanisms for enforcement of the laws and requirements with respect to protection of surface
water quality, groundwater quality, municipal water supplies, and private wells. The overview should
provide a description of organizations responsible for monitoring and regulating HFWC activities.
The final Assessment Report should make clear that the hydraulic fracturing industry is rapidly
evolving, with changes in the processes being employed, whereas the Assessment necessarily was
developed with the data available at a point in time.
3.1.2. Descriptions of Hydraulic Fracturing and Drinking Water Resources
In Chapters 2 and 3, are the descriptions of hydraulic fracturing and drinking water resources clear and
informative as background material?
The description of hydraulic fracturing in Chapter 2 is clear and informative. Regarding time scale, the
EPA should emphasize the relatively short time span of the actual hydraulic fracturing operation within
Chapter 2, and place this emphasis in perspective with the time frames of the other parts of the HFWC.
The SAB finds that the section on site identification and well development should include some
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discussion noting that the geological formations now being targeted for oil and gas production using
hydraulic fracturing and horizontal drilling require closer well spacing that, compared to conventional
drilling methods, may have greater potential impacts on drinking water resources (Zoback and Arent
2014). More discussion of the potential impacts on drinking water resources, both positive and negative,
of well densities and multiple wells on one pad in unconventional oil and gas development should be
included. In addition, the EPA should recognize in Chapter 2 that some oil and gas resources being
developed with the aid of hydraulic fracturing are located in close proximity to large populations.
The description of drinking water resources in Chapter 3 is informative and generally clear. However,
the chapter should include more description and depiction (including diagrams and photographs) of the
natural geologic framework into which the engineered hydraulic fracturing systems are incorporated.
Chapter 3 could also be improved by paying more attention to the local geology and to the physical
properties (thickness, porosity, permeability, fracture density) of the rock layers overlying target
horizons, and including more discussion of the characteristics and proximity of aquifers. In Chapter 3,
the agency should also include more discussion about potential issues associated with future hydraulic
fracturing water supplies and sources (e.g., the chapter should discuss potential issues such as over
pumping or ground subsidence associated with the deeper aquifers in the West if such aquifers are
considered potential future hydraulic fracturing water sources). The EPA should also consider including
a discussion in Chapter 3 on how the EPA and states protect underground sources of drinking water
from oil, gas, and injection wells via well completion standards.
3.1.3. Topics to be Added
Are there topics that should be added to Chapters 2 and 3 to provide needed background for the
assessment?
The EPA should discuss the temporal characteristics of the HFWC stages in Chapter 2 (e.g., the
differences in duration of the actual hydraulic fracturing of the rock versus the duration of production).
In Section 3.2, references to "co-location" of hydraulic fracturing with surface and groundwater should
be clarified.
Within Chapters 2 and 3, the EPA also should discuss new hydraulic fracturing technologies, best
management practices and federal, state and tribal standards and regulations intended to improve
hydraulic fracturing operations associated with each stage of the HFWC. The EPA may develop these
summaries as a longer-term future activity.
Although aquifers are presented on the first page of Chapter 3 as part of the drinking water resources of
the United States, aquifers are only superficially mentioned in the body of the chapter. The EPA should
add more information regarding groundwater resources in hydraulically fractured areas (e.g., typical
depths to aquifers, confined orunconfined aquifers, and aquifer thicknesses). All of this information is
available from the U.S. Geological Survey (USGS 1996; 2000).
The final Assessment Report should discuss the criteria that the agency used to select a one mile radius
to define proximity of a drinking water resource to hydraulic fracturing operations, and the potential
need to consider drinking water resources at distances greater than one mile from a hydraulic fracturing
operation (e.g., in the case of undetected leakage from an impoundment and subsequent long-distance
transport in a transmissive subsurface feature). The final Assessment Report should present more
information regarding the vertical distance between surface-water bodies and the target zones being
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fractured and the depths of most existing and potential future water-supply aquifers compared to the
depths of most hydraulically fractured wells. In addition, in regard to potential impacts on aquifers, the
final Assessment Report should present more information regarding situations where the vertical
distance between the hydraulically fractured production zone and a current or future drinking water
source is relatively small depending on local hydrogeological conditions. Differences in the fracturing
morphology as a function of depth should also be discussed. The EPA should include a graphical
representation of this topic to improve the clarity of the discussion, and consider including graphs from a
2012 publication on microseismic fractures in shale plays (Fisher and Warpinski 2012).
Many of the public comments on the EPA's draft Assessment Report expressed concern that operations
associated with the HFWC had impacted nearby water wells or springs; often describing problems with
attribution even after water testing by homeowners, regulators, or industry. This highlights important
challenges with understanding whether the observed conditions (regarding methane, dissolved mineral
constituents, or other contaminants) existed prior to the drilling; were caused by the drilling and
extraction process; or were caused by other factors. The SAB suggests that the EPA address these issues
in Chapter 4 of the final Assessment Report, with brief descriptions of: (1) Regulatory frameworks of
the oil and gas industry aimed at the protection of source water supplies and the presumption of liability
(over specific setback distances and timeframes); (2) Regulatory frameworks (or lack thereof) of the oil
and gas industry affecting standards for construction of water wells; and (3) Educational needs toward
public understanding of water well construction, maintenance, water testing, and data interpretation.
Some publications on water well construction, maintenance, water testing, and data interpretation that
may assist the EPA in addressing these topics in the final Assessment Report include DeSimone et al.
(2014); Matheson and Bowden (2012); Minnesota Department of Health (2014); and US. Geological
Survey (1994).
Within the final Assessment Report, the agency should also consider including a discussion highlighting
communities experiencing water constraints that are or might be related to hydraulic fracturing activities
in those regions. To the extent that data are available, the EPA could include quantifiable information on
specific local and regional aquifers that are particularly impacted by hydraulic fracturing activities. The
EPA should consider including maps of aquifers similar to the county-specific maps that the EPA
provided within Chapter 3.
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3.2. Water Acquisition Stage in the HFWC
Question 2: The scope of the assessment was defined by the HFWC, which includes a series of activities
involving water that support hydraulic fracturing. The first stage in the HFWC is water acquisition: the
withdrawal of ground or surface water neededfor hydraulic fracturing fluids. This is addressed in
Chapter 4.
a. Does the assessment accurately and clearly summarize the available information concerning
the sources and quantities of water used in hydraulic fracturing?
b. Are the quantities of water used and consumed in hydraulic fracturing accurately
characterized with respect to total water use and consumption at appropriate temporal and
spatial scales?
c. Are the major findings concerning water acquisition fully supported by the information and
data presented in the assessment? Do these major findings identify the potential impacts to
drinking water resources due to this stage of the HFWC? Are there other major findings that
have not been brought forward? Are the factors affecting the frequency or severity of any
impacts described to the extent possible and fully supported?
d. Are the uncertainties, assumptions, and limitations concerning water acquisition fully and
clearly described?
e. What additional information, background, or context should be added, or research gaps
should be assessed to better characterize any potential impacts to drinking water resources
from this stage of the HFWC? Are there relevant literature or data sources that should be
added in this section of the report?
Chapter 4 presents a discussion on water acquisition, in particular the withdrawal of ground or surface
water needed for hydraulic fracturing fluids. The chapter examines the sources, quality and provisioning
of water used during hydraulic fracturing; water use per hydraulic fracturing well (including factors
affecting such use and national patterns associated with that use); cumulative water use and consumption
at national, state and county scales; and a chapter synthesis of major findings, factors affecting the
frequency or severity of impacts, and associated uncertainties.
3.2.1. Summary of Available Information on Sources and Quantities of Water Used in HF
a. Does the assessment accurately and clearly summarize the available information concerning the
sources and quantities of water used in the hydraulic fracturing process?
The assessment regarding the water acquisition stage in the HFWC clearly summarizes available
information concerning the sources and quantities of water used from surface water, groundwater, and
treated wastewaters from CWTFs or POTWs. Chapter 4 of the draft Assessment Report focuses on the
water acquisition stage within the HFWC. The EPA collected, analyzed, and clearly and accurately
summarized an enormous amount of available information about the quantities of water used in
hydraulic fracturing. The analysis of water acquisition for hydraulic fracturing is, from a geographical
standpoint, the most comprehensive to date. Information on water use from surface water, groundwater,
and treated wastewater from CWTFs or POTWs is nicely characterized. References are included
regarding the use or reuse of wastewater, as well as brackish groundwaters containing 3,000-10,000
mg/L TDS that are not currently used as drinking water sources, which lessens the impacts by reducing
the demands on fresh drinking water sources. The analysis and discussion of potential impacts of water
acquisition is focused at large scales, and needs to better address local-scale potential impacts. This
should be considered by the agency for a longer-term future activity. The EPA should improve the
clarity of its summary of sources and quantities in water acquisition for hydraulic fracturing by using
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clearer, more consistent, and technically accurate wording in regard to discussion of potential impacts.
The EPA should also bring findings from the body of the draft Assessment Report on local-scale
impacts into the Executive Summary.
The EPA compared water use in hydraulic fracturing to water use for other purposes. The chapter
concludes that withdrawals for hydraulic fracturing represent a small proportion of freshwater usage at
regional or state-wide levels. The chapter points out that in a small percentage of areas, in particular at
the county and sub-county scale, there is potential for combined impacts from all uses of these sources.
Further, water withdrawals for hydraulic fracturing are also capable of altering the flow regimes of small
streams, even in regions of rainfall abundance. While the SAB concurs with these two findings in the
final Assessment Report, the agency should succinctly summarize the regulatory, legal, management,
and market frameworks in which the HFWC activities are managed that aim to minimize the potential
for these negative impacts. For example, the regulatory framework in Pennsylvania that is discussed in
the draft Assessment Report and its effects on managing water withdrawal could be cited among the
EPA's major findings.
The EPA has produced very informative graphics and tables that substantially improve the public
availability of information characterizing the sources and quantities of water used in hydraulic
fracturing, and the relationship between that use and drinking water. This information is also useful for
focusing future efforts to fill information gaps on sources and quantities of water used in hydraulic
fracturing.
The SAB notes, but did not independently confirm, the EPA conclusion, that there are important gaps in
the data available to assess water use that limit understanding of hydraulic fracturing's potential impacts
on water acquisition, which were identified and discussed in the draft Assessment Report in the context
of areas of uncertainties. The EPA summarized many databases, journal articles, technical reports, and
other information describing sources and quantities in water acquisition for hydraulic fracturing. Some
of this information (especially technical reports, media reports, and presentations at conferences) has not
been peer reviewed, as noted in the draft Assessment Report. The data gaps need to be addressed, as a
longer-term future activity.
The draft Assessment Report relied heavily on two publicly available databases that provide only limited
capability to assess the sources and quantities of water used in the hydraulic fracturing process: (a) the
FracFocus Chemical Disclosure Registry database, where major limitations include questions regarding
data completeness (e.g., including information from all wells in an area); and (b) the Water Use in the
U.S. database from the USGS, where major limitations are associated with limitations of the spatial and
temporal scale of the data (e.g., information is not available at sub-county scales, and information on
water used in hydraulic fracturing is reported as part of larger categories of mining water use).
3.2.2. Total Water Use at Appropriate Temporal and Spatial Scales
b. Are the quantities of water used and consumed in hydraulic fracturing accurately characterized with
respect to total water use and consumption at appropriate temporal and spatial scales?
The draft Assessment Report comprehensively characterizes the quantities of water used and consumed
for hydraulic fracturing at multiple temporal and spatial scales. Though the national scale images of how
water use is distributed across the country are useful and informative, the SAB finds that the EPA's
statistical extrapolation to describe average conditions at the national scale masks important regional and
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local differences in water acquisition impacts. The SAB concludes that the analyses at local scales (e.g.,
case studies) that were used to quantify how hydraulic fracturing water withdrawals affect short-term
water availability are more relevant to spatial and temporal scales for assessing impacts of water
acquisition. The final Assessment Report should discuss regulatory mechanisms that are in place to
address the potential for local impacts.
The draft Assessment Report comprehensively characterizes the quantities of water used and consumed
for hydraulic fracturing with respect to total water use at multiple temporal and spatial scales. The EPA
determined values for the average volume of water used per well using data from broad geographic
areas, and estimated total water use and consumption at national, state, and county scales. The EPA
compared the quantity of water used for hydraulic fracturing to quantities of water used for domestic
purposes, and to total water use for all purposes. The SAB recommends that the EPA expand this
comparison, put water use for hydraulic fracturing into a broader context by including all other primary
categories of water use from the U.S. Geological Survey classification, and update the comparison by
including contemporary values as possible. Further, the EPA should summarize the amounts of water
withdrawn for all uses relative to total annual streamflow.
The potential for the withdrawal of large volumes of water used in the hydraulic fracturing process to
affect water resources is characterized over broad geographic areas, in 15 individual states where
hydraulic fracturing currently occurs. This information is used to scale up the results to consider average
conditions across the nation. Though information on water used in hydraulic fracturing at large spatial
and temporal scales is useful and informative, these are not the most appropriate or relevant scales to
consider the potential problem of water acquisition impacts. Typically, the amount of water used in
hydraulic fracturing would be very small compared to water availability over any large geographic
region (e.g., state or nation) or over any long time frame (e.g., annually), given the short duration of the
water use activity. The volumes of water required in the hydraulic fracturing process are used
infrequently, during initial well completions and re-stimulation operations. The final Assessment Report
should explicitly state that many stresses to surface or groundwater resources associated with water
acquisition and hydraulic fracturing are often localized in space and temporary in time, but nevertheless
can be important and significant.
The discussion of quantities of water used and consumed in hydraulic fracturing is hampered by the lack
of information on water use and availability at local scales, as noted in the draft Assessment Report. The
SAB finds that the EPA should use case studies to quantify the effects of hydraulic fracturing water
withdrawals on short-term water availability, since case studies may provide information on the most
relevant and appropriate spatial and temporal scales discussed in the draft Assessment Report for
assessing the impacts of water acquisition. The SAB anticipates that this further work is anticipated to
involve EPA assessment of a large number of case studies that would explore varying factors such as
climate, geology, water management, and water sources. While the draft Assessment Report discusses
difficulties associated with assessing impacts at local scales where the greatest impacts are likely to
occur, reliable data are generally lacking at local scales, and site-specific factors strongly influence both
water use and water management decisions.
The SAB recommends that the EPA conduct further work, as a longer-term future activity, to explore
how hydraulic fracturing water withdrawals affect short-term water availability at local scales. The
agency should consider the recent publication by Botner et al. (2014) on this topic. The SAB concludes
that the EPA should discuss its plans for performing the water use impact monitoring proposed for the
prospective studies described in the Study Plan (U.S. EPA 2011) but which were subsequently not
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conducted. Two Panel members do not find the lack of prospective case studies to be a limitation to the
draft Assessment Report, based on the perspective that investigations conducted by universities,
consulting firms, and other external stakeholders could be used in lieu of the agency conducting such
studies. The SAB recommends that as a future activity the EPA should collect data available from state
agencies such as the Pennsylvania Department of Environmental Protection on this topic. The EPA
should clarify if any information from the Well File Review included descriptions of water acquired for
hydraulic fracturing at local and site-specific scales.
The EPA should include timeframes associated with time of impact and time of response at a water
system in its analyses to put numeric values in the proper time perspective. The SAB is concerned that
the EPA assessed total use rather than cumulative use. The EPA should consider reviewing the units of
volume and flowrate used in each section of the draft Assessment Report (including Chapters 3 and 4
and Appendix B, which pertain to water acquisition) and consider whether alternate units, or
supplemental units in parentheses, would improve clarity. Further, the EPA should check whether the
volumes or flowrates presented in the draft Assessment Report were accurately presented as percentages
of other volumes or flowrates, to make sure the information is accurately conveyed.
3.2.3. Major Findings
c. 1 Are the major findings concerning water acquisition fully supported by the information and data
presented in the assessment?
The major findings concerning water acquisition for hydraulic fracturing (from surface waters,
groundwaters, and treated wastewaters from CWTFs or POTWs) were generally supported by the
information and data presented in the assessment. However, the finding that there were no cases where
water use for hydraulic fracturing alone caused a stream or well to run dry is not an appropriate criterion
to use to determine occurrence of impacts, since, for example, a stream with substantially decreased
water availability, or a well experiencing regional water-level decline as a result of water acquisition,
may be impacted. While the agency concluded they documented no case of stream impacts associated
with the process of hydraulic fracturing, there may be impacts associated with the HFWC or other
activities that may have occurred. The SAB recommends that the EPA characterize imbalances between
water supply and demand, and localized effects, especially water quality effects, as affected by many
interactive factors. This characterization would provide an improved assessment of impacts (negative or
positive).
The major findings regarding the sources of water acquisition, the range of amounts of water used in
hydraulic fracturing, and the conditions where potential for impacts may occur are supported by the data
presented in the draft Assessment Report. One conclusion was that the amount of water used in
hydraulic fracturing is very small compared with total water use and consumption at county or statewide
spatial scales. The chapter should explicitly state that many stresses to surface or groundwater resources
associated with water acquisition for hydraulic fracturing are often localized in space and temporary in
time, but nevertheless can be important and significant. The impacts of water acquisition would
predominantly be felt locally at small space and time scales, which are not well represented in the draft
Assessment Report. The final Assessment Report should include additional emphasis noting that the
potential for impacts on drinking water resources is greatest in areas with high hydraulic fracturing
water use, low water availability, and frequent drought. This is illustrated within the draft Assessment
Report through examples from case studies. For example, in a study in southern Texas in the Eagle Ford
Shale region, groundwater use caused substantial changes in water storage and drawdown of the water
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table in a relatively small portion of the shale play area; though overall supply was found to be sufficient
in most of the shale play area; as described in Text Box 4-3 of the draft Assessment Report (Scanlon et
al. 2014).
c.2 Do these major findings identify the potential impacts to drinking water resources due to this stage
of the HFWC?
Several case studies were used to explore how hydraulic fracturing water withdrawals affect short-term
water availability. Given the emphasis on local conditions, these case studies are the most relevant to
spatial and temporal scales that were used in the draft Assessment Report for considering potential
impacts to drinking water resources due to hydraulic fracturing water acquisition. These case studies
illustrate how hydraulic fracturing water withdrawals may affect short- and long-term water availability
in areas experiencing high rates of hydraulic fracturing. Results suggest that water imbalances from
hydraulic fracturing operations have not occurred in either the Susquehanna River basin or the upper
Colorado River basin. These studies demonstrated that many local factors and local heterogeneity
explain whether water imbalances occur. However, the SAB finds that since the EPA conducted case
studies on only a few river basins, the role of factors such as climate, geology, water management, and
water sources could not be fully explored.
The EPA should improve the clarity of its major findings regarding the potential impacts to drinking
water resources from water acquisition, and use less ambiguous, more consistent, and technically
accurate wording. For example, the draft Assessment Report states that "Detailed case studies in
western Colorado and northeastern Pennsylvania did not show impacts, despite indicating that streams
could be vulnerable to water withdrawals from hydraulic fracturing. " (emphasis added). However, the
case study report that is cited concludes: "Minimal impacts to past or present drinking water supplies
or other water users resulting from hydraulic fracturing water acquisition were found in either study
basin due to unique combinations of these factors in each area. " (emphasis added). Since "Minimal
impacts" is not the same as "no impacts," the EPA should clarify these findings and results.
c. 3. Are there other major findings that have not been brought forward?
There are several other major findings that the EPA should consider bringing forward. First, the chapter
should more clearly emphasize that many stresses on water resources from water acquisition for
hydraulic fracturing are expected to be localized in space and temporary in time, taking care not to
understate the potential for localized problems. Several of the public commenters, for example,
expressed concern with surface waters taken from small rivers or streams. In such cases the timing of
water withdrawals in relation to flow conditions is important, since withdrawals during low flow periods
may result in dewatering and severe impacts on small streams. More attention needs to be given to
describing the potential impacts on water resources at "hot spots" in space (e.g., headwater streams) and
in time (e.g., seasonally, and/or under low flow conditions). The final Assessment Report should discuss
regulatory mechanisms that are in place to address the potential for local impacts.
Second, the SAB encourages the EPA to explore and describe how water acquisition and associated
potential impacts on lowered streamflow and water tables experiencing local or regional water-level
decline could affect the quality of drinking water, and assess whether such impacts would be short-term
(e.g., a few days) or long-term (e.g., weeks or months). For example, if streamflow is reduced, the final
Assessment Report should describe what might be the effects on chloride or total dissolved solids
concentrations in streamflow, and how this might affect water supply and treatment costs. The SAB also
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recommends that the EPA conduct a more thorough study of this issue, including a detailed economic
analysis, as a long-term future activity.
Third, reuse of hydraulic fracturing-related wastewater and produced formation water are described in
the draft Assessment Report, and the EPA should expand on the discussion of the evolution and
utilization of technologies being used to facilitate use and reuse of produced water and use of other
historically underutilized sources of water (e.g., seawater, brackish groundwater containing 3,000-
10,000 mg/L TDS, mine drainage, and treated wastewater) that if used for hydraulic fracturing (or other
purposes) could reduce the impacts of water acquisition on drinking water sources. While most
geographic areas show a very low percentage of reuse as a source of water for hydraulic fracturing, the
reuse percentages in some regions can be high. The EPA should consider exploring and describing
within the final Assessment Report how and why the Garfield County region in Colorado (Piceance
Basin) is able to use 100% wastewater for hydraulic fracturing (as indicated in Table 4-1 of the draft
Assessment Report). This situation may be due to a combination of a dry climate, the wastewater
quantity and quality in this area, that the area has been unitized (with all operators sharing infrastructure
to produce the fields), and that the area is mature (having been one of the early areas of unconventional
oil and gas development). The SAB also notes that the use of municipal wastewater for hydraulic
fracturing could remove this source for future consideration as a permanent or emergency water supply.
3.2.4. Frequency or Severity of Impacts
c. 4. Are the factors affecting the frequency or severity of any impacts described to the extent possible
andfully supported?
The description of the frequency of impacts is highly generalized and qualitative. Though the statements
about factors affecting the frequency and severity of impacts are reasonable, the SAB recommends that
the EPA strengthen and clarify the general statements within the draft Assessment Report by adding
more specific and quantitative results. The draft Assessment Report explains thoroughly the potential for
impacts and the types of conditions that warrant caution with respect to both water quantity and quality
impacts at local scales. The draft Assessment Report proposes that proper water management in these
areas may be able to reduce the potential impacts, which may include adding the use of non-drinking
water sources, and examples of this are shown in the draft Assessment Report.
The draft Assessment Report noted that there were no cases where water use for hydraulic fracturing
alone caused a stream or well to run dry, yet the SAB finds that this is not an appropriate criterion to use
to determine occurrence of impacts, since, for example, a stream with substantially decreased water
availability, or a well experiencing regional water-level decline as a result of water acquisition, may be
impacted. While the agency concluded they documented no case of stream impacts associated with the
process of hydraulic fracturing, there may be impacts associated with the HFWC or other activities that
may have occurred. The SAB recommends that the EPA characterize imbalances between water supply
and demand, and localized effects, especially water quality effects, as affected by many interactive
factors. This characterization would provide an improved assessment of impacts (negative or positive.)
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3.2.5. Uncertainties, Assumptions and Limitations
d. Are the uncertainties, assumptions, and limitations concerning water acquisition fully and clearly
described?
The draft Assessment Report fully and clearly describes the uncertainties, assumptions, and limitations
about water acquisition for hydraulic fracturing. The SAB notes, but did not independently confirm, the
EPA conclusion, that there are reportedly important gaps in the data and information available to assess
water use. The EPA summarizes a vast quantity of information from databases, journal articles,
technical reports, and other sources of information that describes sources and quantities in water
acquisition for hydraulic fracturing. Some of this information (especially technical reports, media
reports, and presentations at conferences) has not been peer reviewed, as noted in the draft Assessment
Report.
The FracFocus Chemical Disclosure Registry (http://fracfocus.org) is a database platform managed by
the Groundwater Protection Council (GWPC) and the Interstate Oil and Gas Compact Commission
(IOGCC). This database includes information on water and chemical use, as reported by the oil and gas
industry. Potential limitations and uncertainties of this dataset for this assessment stem from incomplete
information on all oil and gas wells, and from the reliability of the unverified information. Another
database EPA utilized is the Water Use in the United States database (http://water.usgs.gov/watuse/).
compiled by the U.S. Geological Survey. This includes data on water used by source and category, as
reported by local, state, and federal environmental agencies. Potential limitations and uncertainties of
this dataset are associated with the spatial and temporal scale of the information presented (by county
and state, in five-year intervals), the categories of data (e.g., with data definitions changing over time,
and with water used for hydraulic fracturing reported as part of a larger overall category of water use
associated with mining). The EPA should update, as a longer-term future activity, the study results with
the latest information from the current versions of these databases.
An additional source of uncertainty is the reportedly poor quality and sparse information on specific
water withdrawals from groundwater, streams, and surface-water reservoirs. Although data on locations
and volumes of water withdrawal are available for some regions (e.g., Pennsylvania's Susquehanna
River Basin), this sort of information is reportedly not recorded, or is at least inaccessible, for several
states included in the EPA's analysis. The availability or absence of data may reflect differences in
regulations and regulatory oversight. The SAB recommends that the EPA include within Chapter 4 a
review of the regulatory landscape governing water withdrawals for hydraulic fracturing.
The SAB also recommends that the EPA evaluate the various regulatory approaches for their efficacy in
safeguarding against freshwater depletion at local scales. The EPA should compile the various
regulatory approaches in local areas that should be succinctly summarized within the final Assessment
Report, and conduct evaluation of these approaches for their efficacy in safeguarding against freshwater
depletion at local scales. The EPA may consider addressing both of these recommendations as a longer-
term activity.
At local scales, where the greatest impacts are most likely to occur, the draft Assessment Report
describes these data as generally lacking. The case studies included in the draft Assessment Report
demonstrate that local heterogeneity and site-specific factors determine water imbalances at local sites,
and that results cannot be extrapolated to entire river basins. The EPA should, as a longer-term future
activity, enhance the understanding of localized impacts by providing more focus and analysis on the
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Well File Review and on examining other information not in the archival scientific literature and
common databases to provide updated information about actual hydraulic fracturing water acquisition
and its relationship to drinking water, and about water availability compared to other users of the
resource including agricultural, recreational, and industrial uses, and less focus on hypothetical scenarios
and modeling.
3.2.6. Information, Background or Context to be Added
e. 1. What additional information, background, or context should be added, or research gaps should be
assessed to better characterize any potential impacts to drinking water resources from this stage of the
HFWC?
Given limitations in the reported availability of data on water consumption and use, especially at local
scales, and in the representativeness of the case studies used, many interactive factors that influence the
potential for effects of hydraulic fracturing on water availability and quality (e.g., climate, geology,
water management, and multiple water sources) could not be fully characterized.
One of the key limitations toward understanding the potential impacts of hydraulic fracturing water
acquisition on drinking water is the availability and reliability of data. The EPA should articulate what
datasets were requested and reviewed as part of this report, what future needs are recommended for
reliable, independent data on water use and consumption that may better facilitate assessment of
potential impacts to drinking water resources, and which agencies excel at data base management.
Another area for improvement is the EPA's reliance on the publicly available databases for this draft
Assessment Report, including the FracFocus Chemical Disclosure Registry database. The SAB
identifies concerns regarding the EPA's reliance on an early version of the FracFocus database, and
provides suggestions for acknowledging and addressing these concerns, within the Executive
Summary's Thematic Areas for Improving the Draft Assessment Report and also within Section 3.2.5 of
this SAB Report.
The EPA could reduce gaps in understanding the relationship between water acquisition for hydraulic
fracturing and drinking water by using available information from the Well File study database that the
EPA developed to support the draft Assessment Report. The EPA's 2012 Progress Report identified the
Well File Review as a key data source for many aspects of the relationship between hydraulic fracturing
and drinking water, including water acquisition, yet the 2015 Well File Review Report does not contain
any information about water acquisition, and that report is not cited in Chapter 4 of the draft assessment.
Within the final Assessment Report, the EPA should add at least a brief summary of the information
about water acquisition that was provided by the Well File Review and explain why that information
was not included within the Assessment Report.
The case studies are limited in terms of the sites and associated environmental conditions that they
represent and the results are not readily transferrable to other areas. Therefore, many interactive factors
that need to be considered toward understanding effects of the HFWC on water availability and quality
(e.g., climate, geology, water management, and multiple water sources) could not be fully characterized.
The agency should, as a longer-term future activity, continue to explore how hydraulic fracturing water
withdrawals affect short-term water availability at local scales.
The EPA could, as a longer-term future activity, articulate how reported (or purported) cases of water
acquisition impacts on drinking water actually occurred, and to what extent the factors controlling the
frequency and extent of these impacts are being addressed by improved operator practices, and
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regulatory oversight. Controversial or contentious sites should not be ignored, but addressed directly.
The draft Assessment Report does not focus adequate attention on local experiences of water impacts
prior to and during the study period that have been described in local newspapers, media coverage,
agency reports, and/or publications. Such attention in future efforts would provide more information on
the frequency and severity of impacts based on actual experiences.
To address these gaps and uncertainties, the agency should, as a longer-term future activity: (1)
synthesize information that is collected by the states but not available in mainstream databases, such as
well completion reports, permit applications, and the associated water management plans; and (2) assess
whether there are specific local and regional aquifers that are particularly impacted by HFWC activities,
and if so, provide quantifiable information on this topic. For example, as noted in the draft Assessment
Report, water use management in the Susquehanna River basin and other areas is credited with
minimizing the impact of hydraulic fracturing withdrawals on stream flow.
The EPA should describe best management practices being implemented by the States or other
regulatory agencies. For example, in the Susquehanna River Basin, the Susquehanna River Basin
Commission (SRBC) has the regulatory authority and has well-established programs in permitting,
collecting, monitoring and managing water resources. The EPA may develop this summary as an item
for longer-term future activity.
For the Susquehanna River Basin, the EPA could present more detail, using monitoring data from
industry and from the SRBC, to develop a better understanding of how hydraulic fracturing could have
impacted the drinking water due to temporal dynamics. The agency should also describe SRBC
regulations for low-flow conditions of streams during which operators are prohibited from withdrawing
water. The EPA should consider exploring these dynamics at local scales by examining these and other
water use management events.
The EPA should describe the scale of the task in gathering and organizing data collected from the states.
Within the final Assessment Report, the EPA is encouraged to describe its efforts to investigate data
available from state agencies, and describe what critical lessons were learned from the effort.
e2. Are there relevant literature or data sources that should be added in this section of the report?
The SAB encourages the EPA to use additional available information from the Well File Review study
database to characterize potential water acquisition impacts, as planned in the 2012 Progress Report.
The EPA also should review the following additional literature and data sources related to water
acquisition for potential inclusion in this section of the final Assessment Report:
• Barth-Naftilan, E., N. Aloysius, and J. E. Saiers. 2015. Spatial and temporal trends in freshwater
appropriation for natural gas development in Pennsylvania's Marcellus Shale Play. Geophys.
Res. Lett. 42, doi: 10.1002/2015GL065240.
• DeSimone, L.A., P.B. McMahon, and M.R. Rosen. 2014. The quality of our nation's waters—
water quality in principal aquifers of the United States, 1991-2010. U.S. Geological Survey
Circular 1360, 151 p. http://dx.doi.org/10.3133/cirl360 Available at
http://pubs.usgs.gov/circ/1360/pdf/circl360report.pdf
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• Entrekin, S.A., K.O. Maloney, K.E. Kapo A.W. Walters, M.A. Evans-White, and K.M. Klemow.
2015. Stream vulnerability to widespread and emergent stressors: a focus on unconventional oil
and gas. PLoS ONE 10(9): e0137416. doi: 10.1371/journal.pone.0137416
• Fisher, M., and N. Warpinski. 2012. Hydraulic fracture height growth: Real data. SPEProd.
Oper. 27: 8-19. http://dx.doi.org/10.2118/145949-PA
• Freyman, M. 2014. Hydraulic fracturing and water stress: Water demand by the numbers.
Shareholder, lender & operator guide to water sourcing. Ceres report. Online URL:
http://www.ceres.org/issues/water/shale-energy/shale-and-water-maps/hvdraulicfracturing-water-
stress-water-demand-bv-the-numbers
• Hildenbrand, Z.L., D.D. Carlton Jr., B.E. Fontenot, J.M. Meik, J.L. Walton, J.T. Taylor, J.B.
Thacker, S. Korlie, C.P. Shelor, D. Henderson, A.F. Kadio, C.E. Roelke, P.F. Hudak, T Burton,
H.S. Rifai, and K.A. Schug. 2015. A comprehensive analysis of groundwater quality in the
Barnett Shale Region. Environ. Sci. Technol. 49(13), p. 8254-8262. DOI:
10.102 l/acs.est.5b01526.
• Jackson, R.B., E.R. Lowry, A. Pickle, M. Knag, D. DiGiulio, and K. Zhao. 2015. The depths of
hydraulic fracturing and accompanying water use across the United States. Environ. Sci.
Technol 49(15), p. 8969-8976. doi: 10.102 l/acs.est.5b01228.
• Matheson, M., and J. Bowden. 2012. How well do you know your water well? Available at:
http ://epa. ohio.gov/Portal s/0/general0 o20pdfs/HowW ellDoY ouKnowY ourW aterW ell.pdf
• Minnesota Department of Health. 2014. Well owner's handbook - a consumer's guide to water
wells in Minnesota. Well Management Section, Environmental Health Division, Minnesota
Department of Health. Available at:
http://www.health.state.mn.us/divs/eh/wells/construction/handbook.pdf.
• Rahm, B.G., and S.J. Riha. 2012. Toward strategic management of shale gas development:
Regional, collective impacts on water resources. Environ. Sci. & Pol. 17, p. 12-23. March 2012.
doi: 10.1016/j.envsci.2011.12.004.
• Rahm, B.G., J.T. Bates, L.R. Bertoia, A.E. Galford, D.A. Yoxtheimer, and S.J. Riha. 2013.
Wastewater management and Marcellus Shale gas development: trends, drivers, and planning
implications. J. Environmental Management 120, p. 105-113. May 15, 2013. doi:
10.1016/j.jenvman.2013.02.029. Online URL: http://dx.doi.org/10.1016/i.ienvman.2013.02.029.
• Reig, P., T. Luo, and J.N. Proctor. 2014.World Resources Institute, Global Shale Gas
Development: Water Availability & Business Risks, September 2014.
• Shank, M. K., and J. R. Stauffer Jr. 2014. Land use and surface water withdrawals effects on fish
and macroinvertebrate assemblages in the Susquehanna River basin, USA. J. Freshwater Ecol.
13. doi: 10.1080/02705060.2014.959082.
• USGS (U.S. Geological Survey). 1994. Ground water and the rural homeowner. Available at:
http://pubs.usgs.gov/gip/gw ruralhomeowner/.
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• Vengosh, A., R.B. Jackson, N. Warner, T.H. Darrah, and A. Kondash. 2014. A critical review of
the risks to water resources from unconventional shale gas development and hydraulic fracturing
in the United States. Environ. Sci. Techno/. 48(15), p. 8334-8348. March 7, 2014. DOI:
10.1021/es405118y.
3.3. Chemical Mixing Stage in the HFWC
Question 3: The second stage in the HFWC is chemical mixing: the mixing of water, chemicals, and
proppant on the well pad to create the hydraulic fracturing fluid. This is addressed in Chapter 5.
a. Does the assessment accurately and clearly summarize the available information concerning
the composition, volume, and management of the chemicals used to create hydraulic
fracturing fluids?
b. Are the major findings concerning chemical mixing fully supported by the information and
data presented in the assessment? Do these major findings identify the potential impacts to
drinking water resources due to this stage of the HFWC? Are there other major findings that
have not been brought forward? Are the factors affecting the frequency or severity of any
impacts described to the extent possible and fully supported?
c. Are the uncertainties, assumptions, and limitations concerning chemical mixing fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water resources
from this stage of the HFWC? Are there relevant literature or data sources that should be
added in this section of the report?
Chapter 5 presents a discussion on the chemical mixing of water, constituents, and proppant on the well
pad to create the hydraulic fracturing fluid. The chapter examines the chemical mixing process; provides
an overview of hydraulic fracturing fluids including discussions on water-based fluids, alternative fluids,
and proppants (granular additives such as fine sand injected to hold open microfractures); and discusses
the frequency and volume of hydraulic fracturing constituent use. The chapter describes the frequency
with which hydraulic fracturing constituents are used at the national scale, oil vs. gas usage of
constituents nationally, and a state-by-state discussion on the frequency of hydraulic fracturing
constituent use. Chapter 5 also examines constituent management and spill potential associated with
hydraulic fracturing operations, constituent storage, hoses and lines, blending operations, manifolding
(bringing together multiple fluid flow lines), high-pressure pumps, and surface wellhead fracture
stimulation. In addition, Chapter 5 presents a discussion on spill prevention, containment, and mitigation
associated with hydraulic fracturing operations, fate and transport of hydraulic fracturing constituents,
trends in constituents used in hydraulic fracturing, and a chapter synthesis of major findings, factors
affecting the frequency or severity of impacts, and uncertainties.
3.3.1. Composition, Volume and Management of Hydraulic Fracturing Constituents
a. Does the assessment accurately and clearly summarize the available information concerning the
composition, volume, and management of the chemicals used to create hydraulic fracturing fluid.
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The chemical mixing stage of the HFWC includes a series of above ground, engineered processes
involving complex fluid pumping and mixing operations, and the potential failure of these processes,
including on-site and near-site containment, poses a potential risk to drinking water supplies. The draft
Assessment Report does not accurately and clearly summarize the available information concerning the
composition, volume, and management of the constituents used to create hydraulic fracturing fluid.
Chapter 5, as it stands, provides little information on the magnitude of hydraulic fracturing spills and it
does not adequately describe either the uncertainty associated with the data or the lack of understanding
of such spills. Consequently, the EPA should revise its assessments associated with this stage of the
HFWC to address these concerns. An accurate assessment would detail data gaps and quantitative
uncertainties and provide an overall evaluation of the actual state of knowledge. The chapter is a
general, mostly qualitative, description of industrial mixing processes and fluid compositions. Many
public commenters expressed the view that a substantial fraction of chemical additives are unknown,
either by identity or behavior. This chapter does little to educate and alleviate the basic concerns
regarding the composition of hydraulic fracturing fluids and, by extension, how they would behave after
a spill. The agency should revise Chapter 5 of the draft Assessment Report to provide more information
regarding the extent or potential extent of the effects of chemical mixing processes associated with
hydraulic fracturing operations on drinking water supplies.
HFfluids: The draft Assessment Report's discussion of hydraulic fracturing fluids and their properties
is primarily based upon the FracFocus 1.0 database. A lack of verification of the accuracy and
completeness of the FracFocus information (page 5-73) makes conclusions regarding the data that are
reported uncertain. The SAB identifies issues with the EPA's reliance on the FracFocus version 1.0
database, and provides suggestions for acknowledging and addressing these concerns, within the
Executive Summary's Thematic Areas for Improving the Draft Assessment Report and also within
Section 3.2.5 of this SAB Report.
The draft Assessment Report broadly describes the extent of the constituent data record but should be
critical of what is not known and the consequences of this uncertainty. As such, the SAB does not
recommend that the EPA make generalizations regarding how constituents will behave. Since the
majority of hydraulic fracturing fluids are aqueous-based, concentrations in this report are calculated
based on water as the solvent. However, the SAB finds that the description of concentrations becomes
confusing, and likely inaccurate, when non-aqueous-carrier phases such as methanol are the dominant
liquid. To address these concerns, the SAB recommends that the final Assessment Report provide a
more rigorous explanation of volume, concentration, mass and chemical activity as it relates to the
solvent. The final Assessment Report should provide a critical analysis of the type of data needed to
provide a meaningful assessment of spill severity and impact, including description of the types of data
available from state agencies. If the appropriate data are not currently available (e.g., the masses of
constituents spilled have not been reported), then the final Assessment Report needs to detail the data
that must be acquired by states so that critical assessments can be made.
In addition, novel hydraulic fracturing fluids (e.g., energized fluids, foams, and gases) are currently in
development, and the Assessment Report should provide further discussion regarding the impacts of
these fluids on water quality, and the degree to which use of these fluids reduce water quantity
requirements for flowback and produced water.
Chemical mixing and delivery processes: The section on chemical mixing and delivery processes
provides a broad overview of the steps involved (i.e., 'phases'; Fig. 5-3) as well as a description of the
actual 'mechanical' actions involved, such as types of pumping equipment and hose operations. The
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fluid transfer steps of chemical mixing and delivery are key potential sources of spilled liquids to
containment structures or directly to the environment. The SAB recommends that the EPA
explain/assess the efficiency (i.e., failure rates) of these operations, and provide more information on:
(1) the potential for spilled liquids during routine operations; and (2) actions that can improve spill
prevention. For example, Figure 5.13 indicates that approximately one-third of spilled liquids are
sourced to 'equipment' or 'hose or line' failure. The EPA should describe whether these spills are the
consequence of many small leaks or substantial ones. Additionally, the agency should discuss if these
spills are within "site containment" or "outside containment" structures. Page 5-43, line 17, notes that
60% of spilled liquids in Colorado were caused by equipment failure, and the EPA should describe what
is the source of the variability in the origin of these spills within the final Assessment Report, with an
emphasis on what was spilled "outside containment."
Another source of uncertainty is the behavior of mixed constituents. To a certain extent the sub-text of
the discussion is that the various additives behave 'conservatively' (i.e., are non-reactive) upon mixing.
The EPA should describe what occurs when an acid comes into contact with some of the organic
additives, and whether constituent behavior depends on the solvent (i.e., water or methanol). Similarly,
the agency should improve this section by including practical information on spill mitigation practices
such as secondary containment, berm construction to prevent surface transport, and barriers to prevent
spilled hydraulic fracturing fluids from reaching the ground surface, subsurface, and groundwater.
Chemical and spill management and potential impacts on the environment: Within the Chapter 5
discussion on constituent and spill management and potential impacts on water resources, the datasets
for spills are incomplete, at least those that are readily available in electronic format. The SAB notes that
the EPA's estimates on the frequency of on-site spills were based upon information from two states.
While the SAB recognizes that the states of Pennsylvania and Colorado likely have the most complete
datasets on this topic that the EPA could access, the SAB finds that the draft Assessment Report's
analysis of spill data cannot be extrapolated across the entire United States. The SAB also notes that
geologies commonly vary within and between states and this limits potential extrapolation of this dataset
towards topics other than frequency of spills (e.g., while the geology may not have a large effect on the
frequency or volume of a spill, the dataset could be used to assess issues regarding the fate and potential
impacts of spilled hydraulic fracturing constituents in different geologies). The SAB encourages the
agency to contact state agencies, review state databases and update the draft Assessment Report to
reflect a broader analysis. While the SAB recognizes that state database systems vary, the databases
should be incorporated into the EPA's reporting of metrics within the final Assessment Report. The
SAB recommends that the agency revisit a broader grouping of states and "refresh" the final Assessment
Report with updated information on the reporting of spills associated with HFWC activities. The EPA
should address this significant 'completeness' issue in this section of Chapter 5, and describe the extent
and types of spill reporting to states. The SAB also recommends that the final Assessment Report
include a more thorough presentation and explanation of the frequency and types of data that the
hydraulic fracturing industry reports, some of which may not be readily accessible (i.e., not in electronic
format that is 'searchable'). For example, Reference [5] (noted below under the 'additional types of data
sources to consider' section of this response to charge question 3) documents that a substantial number
of uncontained spills have occurred during North Dakota oil field operations. The SAB notes that while
many of these spills may not be strictly part of the chemical mixing step, these spills provide
information on the integrity of fluid management operations in general. The EPA over-interpreted this
limited data in its conclusion that the risk to drinking water supplies from this stage of the HFWC is not
substantial, and the EPA should revise this interpretation of these limited data.
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Trends in constituent use in hydraulic fracturing operations: Section 5.9 of the draft Assessment
Report describes ongoing changes in the hydraulic fracturing industry in the form of developing
fracturing fluid additives that the EPA considers to be 'safer' to the environment. The SAB notes that
this section is not a critical review of such efforts. However, the SAB also notes that little is known
about certain hydraulic fracturing fluid constituents and their safety. The SAB recommends that the EPA
clarify in this section of the final Assessment Report that many issues may play an important role in the
hydraulic fracturing industry's substitution of fracturing fluid additives for currently used additives. The
SAB also recommends that the agency expand this chapter to include a more critical evaluation of this
trend in hydraulic fracturing and how the industry has further limited the number of constituents used in
the completion process.
3.3.2. Major Findings
bl. Are the major findings concerning chemical mixing fully supported by the information and data
presented in the assessment?
The EPA's major finding and conclusion described in Section 5.10.1 of the draft Assessment Report that
there were 'no documented impacts to groundwater' for the 497 spills evaluated by the EPA, and in
Section 10.1.2., on page 10-8, and on page ES-13, where the EPA notes that "None of the spills of
hydraulic fracturing fluid were reported to have reached groundwateris not supported by the
information and data presented in the draft Assessment Report, due to the EPA's incomplete assessment
of spilled liquids and consequences. All but one Panel member are concerned that this major finding is
supported only by an absence of evidence rather than by evidence of absence of impact. The EPA should
assess the likelihood of detecting an impact given the current state of groundwater and surface water
monitoring in the United States. If routine monitoring systems are adequate to capture this impact if it
occurred, then a lack of evidence of impact may support a conclusion that there was no impact. If the
routine monitoring systems would not be expected to capture an impact that occurred, then a lack of
evidence of impact may not support a conclusion of no impact. The 'available information' has been
broadly summarized in the draft Assessment Report but the limitations of the data sources (e.g.,
FracFocus) appear to have led to an incomplete record associated with the potential impacts associated
with such spills. The SAB identifies issues regarding the EPA's reliance on the FracFocus version 1.0
database, and provides suggestions for acknowledging and addressing these concerns, within the
Executive Summary's Thematic Areas for Improving the Draft Assessment Report and also within
Section 3.2.5 of this SAB Report. Further, there is a lack of a critical assessment of the data presented in
this chapter in a number of instances, and the SAB concludes that the EPA needs to conduct such critical
assessment to support conclusions that the EPA may make on such data. For example, while the EPA
considers spill volume to be an indicator of potential severity, spill volume is not necessarily an
indicator of potential severity because the composition of spilled fluids, including chemical species and
concentrations, plays an important role in determining the severity of a potential environmental threat
resulting from a spill.
Relationship between the chemical mixing step of the HFWC and drinking water quality: A
secondary conclusion of the draft Assessment Report is that there is reportedly insufficient information
to assess the relationship between the chemical mixing step of the HFWC and drinking water quality
(Section 5.10.3). The SAB finds that the data presented by the EPA within Chapter 5 supports an
occurrence of spilled liquids at hydraulic fracturing sites, and that there are varying causes, composition,
frequency, volume, and severity of such spills. The SAB finds that a substantial problem with the
synthesis presented in this chapter is the lack of a full and accurate description of the uncertainty
surrounding the EPA's conclusion. An example of this problem is the statement provided on page 5-71,
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line 14 of the draft Assessment Report noting: "The EPA analysis of 497 spills reports found no
documented impacts to groundwater from those chemical spills, though there was little information on
post-spill testing and samplingThe EPA should summarize efforts made to review spill files from the
states on each of these cases to determine what "post remedial sampling" was conducted. At the same
time, the EPA cites Gross et al. (2013), which examined the Colorado Oil and Gas Conservation
Commission (COGCC) spill database for 2010 to 2011. Gross et al. (2013) write that:
We analyzed publically available data reported by operators to the COGCC regarding
surface spills that impacted groundwater. From July 2010 to July 2011, we noted 77
reported surface spills impacting the groundwater in Weld County, which resulted in surface
spills associated with less than 0.5% of the active wells.
The SAB is concerned that this information raises questions regarding how the agency actually analyzed
spills as part the draft Assessment Report. The SAB recommends that the EPA clarify its statements in
the final Assessment Report on the lack of data on spills, and also clarify whether the reported apparent
lack of data is reflective of non-existent data or data reported somewhere but are not readily available.
The SAB also recommends that the agency expand this chapter of the final Assessment Report to
provide improved analysis on the current state of data reporting on spills and the nature of hydraulic
fracturing fluids
An additional point is that the draft Assessment Report conflates spill frequency and spill volume with
spill severity. The final Assessment Report should define "severity" in a way that is amenable to some
sort of quantitative analysis and clearly delineate those factors contributing to spill severity (e.g., the
mass of a spilled constituent that has the potential to reach an environmental receptor, and the toxicity of
spilled constituents). Additionally, a number of states have spill reporting requirements, and processes,
that may not yield data that are readily available in electronic, searchable form. The SAB recommends
that the EPA investigate at least one state as a detailed example for scrutinizing the spill data (e.g., see
North Dakota Department of Health 2015). The final Assessment Report should include a discussion of
this investigation and analysis
FracFocus 1.0: The EPA primarily used FracFocus version 1.0 during its study period to support most
of the data assessment associated with EPA's development of the draft Assessment Report. The EPA
outlines limitations of FracFocus data within the draft Assessment Report, and the SAB agrees with
those observations and expresses additional questions regarding the use of these data. The SAB finds
that a central problem regarding use of the FracFocus 1.0 dataset is that it does not represent the full
suite of hydraulic fracturing operations taking place within the United States during the study period. A
lack of verification of the accuracy and completeness of the FracFocus information makes conclusions
regarding the data that are reported uncertain. The SAB identifies a number of additional concerns
regarding the EPA's reliance on the FracFocus version 1.0 database, and provides suggestions for
acknowledging and addressing these concerns, within the Executive Summary's Thematic Areas for
Improving the Draft Assessment Report and also within Section 3.2.5 of this SAB Report.
b2. Do these major findings identify the potential impacts to drinking water resources due to this stage
of the HFWC?
The major findings presented in Chapter 5 of the draft Assessment Report do not identify the potential
impacts to drinking water resources due to the chemical mixing stage of the HFWC. The SAB concludes
that 'potential impacts' is inherently an issue of severity, and as described further under the response to
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sub-question b.4 of this charge question, the chapter does not provide the basis for understanding the
potential for spills affecting drinking water supplies. The SAB finds that a conclusion on potential
impact is a quantitative function of (at least) spill composition, frequency, containment probability,
response adequacy, and the transport of constituents to environmental receptors. The SAB finds that the
EPA does not adequately evaluate any of these factors in a manner to provide sufficient quantitative
assessment of potential impacts and severity.
h3. Are there other major findings that have not been brought forward?
There are three areas of uncertainty in this chapter of the draft Assessment Report that should be
described more clearly in the final Assessment Report:
1. Uncertainty regarding undetected and unmonitored hydraulic fracturing constituents. There is
uncertainty regarding which hydraulic fracturing constituents are currently in use. A crucial
oversight within the draft Assessment Report is the lack of discussion on the degree of undetected,
unmonitored hydraulic fracturing constituents and analytical assessment of the many uncommon
constituents used in hydraulic fracturing. The SAB recommends that the EPA assess impacts and the
underlying uncertainty associated with these undetected, unmonitored hydraulic fracturing
constituents and incorporate such an assessment into this chapter of the final Assessment Report.
This assessment should also consider how many hydraulic fracturing constituents that are in use do
not have analytical methods, and are not undergoing monitoring.
2. Uncertainty regarding the identity of hydraulic fracturing constituents used in particular hydraulic
fracturing operations, as compounded by limited knowledge about on-site storage of constituents.
There is uncertainty regarding the identity of constituents used in particular hydraulic fracturing
operations, and this uncertainty is compounded by limited knowledge about on-site hydraulic
fracturing constituent stockpiles. These stockpiles may change markedly over the time period of a
hydraulic fracturing operation. Container failure is a primary source of hydraulic fracturing spills,
and the effectiveness of spill containment is of interest in understanding response measures,
sampling and closure. The reports of most spills discussed in the draft Assessment Report included
little or no field investigation of the impacts of the release, or any documented after-spill
investigation of suspected constituent contamination. The EPA should bring such information, either
by direct EPA study or analogue studies, into the final Assessment Report.
3. Uncertainty regarding spills and their associated impacts. There is uncertainty regarding the
frequency, severity, and type of HFWC-related spills, and the agency should address this uncertainty
in this chapter of the final Assessment Report. The EPA should conduct, or at least include a plan
for, a detailed study of state reports on spills (perhaps one example target state) with a full statistical
analysis. A future study should include: (a) the state of practice by the industry in spill monitoring
and reporting; (b) an assessment of state records regarding spills; and (c) a more rigorous scientific
description of potential severity of spilled liquids (e.g., type of spill, concentration of constituents,
and volume).
To reduce these uncertainties, the EPA should make Chapter 5 more current by including more recent
available data, and conduct a more comprehensive and thorough analysis on the available data, on these
topics.
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3.3.3. Frequency or Severity of Impacts
b4. Are the factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
The factors affecting the frequency or severity of any impacts associated with HFWC-related spills are
not described to the extent possible nor are they fully supported. While the EPA conducted a large effort
in developing Chapter 5, the SAB is concerned that two fundamental, underlying questions have not
been answered: What is the potential that spills occurring during the chemical mixing process affect
drinking water supplies, and what are the relevant concerns associated with the degree to which these
spills impact drinking water supplies? One Panel member finds that the draft Assessment Report
provided a thorough description of the variables associated with a spill (i.e., amount, duration, soils,
weather, groundwater, surface water, constituents released, and other spill aspects), and noted that the
Report should provide more granularity on how states respond to spills.
This chapter addresses five linked topics: (1) chemical mixing and delivery processes; (2) description of
hydraulic fracturing fluid components and their properties; (3) the potential impacts of hydraulic
fracturing fluids on the environment, including spill volume and frequency; (4) principles of
environmental fate and transport of potentially spilled hydraulic fracturing fluids; and (5) trends in
constituent use in hydraulic fracturing operations. To conduct a 'severity' analysis, the EPA must assess
each of the above factors in such a way that a quantitative assessment of likelihood can be derived. By
these criteria, the SAB finds that the EPA's assessment towards each of these linked topics is in need of
substantial improvement.
The SAB recommends that the EPA substantially modify the discussion in Section 5.8 on fate and
transport of spilled hydraulic fracturing constituents. The SAB finds that this section portrays that more
is known about fate and transport of hydraulic fracturing constituents than is actually known. This
section's discussion is not useful to this chapter because it does not describe the uncertainty about
severity of hydraulic fracturing spills. The SAB finds EPA's descriptions of the classes of constituents
and their range of uses as useful information. However, the SAB recommends that the EPA combine
detailed chemical property information with similar information provided elsewhere in the draft
Assessment Report (e.g., Chapter 9). The SAB also recommends that the EPA minimize the value of the
speculative transport scenarios that the agency assessed and reported on in this chapter. The SAB
concludes that there are too many factors affecting the fate of hydraulic fracturing constituents in the
environment for the EPA to use octanol-water partition coefficient (Kow) as a proxy for relative mobility.
These other factors include, for example, fate issues associated with constituents in mixtures,
constituents in non-aqueous phases, and the nature of the environmental media into which these
hydraulic fracturing constituents may be released.
3.3.4. Uncertainties, Assumptions and Limitations
c. Are the uncertainties, assumptions, and limitations concerning chemical mixing fully and clearly
described?
The SAB finds that the reported uncertainties, assumptions, and limitations concerning chemical mixing
are not fully and clearly described. Data limitations compromise the EPA's ability to develop definitive,
quantitative conclusions within the draft Assessment Report regarding the frequency and severity of
spilled liquids. Data limitations do not constitute evidence that water resources are unaffected; rather,
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these limitations indicate the lack of inclusion of monitoring information from hydraulic fracturing sites
described within the draft Assessment Report, and the lack of a thorough assessment of the uncertainties
of each chemical mixing section of Chapter 5 of the draft Assessment Report. The details of the
monitoring required to assess severity (and not simply what monitoring has already been conducted) is
not and should be included in Chapter 5. A further complication is that analytical protocols for many
constituents used in hydraulic fracturing operations do not exist, and the lack of detection of such
constituents does not mean they are not present in the environment. To address these concerns, although
the final Assessment Report is not intended to be a risk analysis, the SAB recommends that the EPA
include in this chapter a detailed analysis of the failure rates of the fluid handling equipment and the
efficiency of containment measures. Furthermore, within each section of this chapter, the EPA should
include a critical assessment of data gaps, statements of what is needed to close those gaps, and an
explicit statement of uncertainty associated with the topics covered within these sections.
3.3.5. Information, Background or Context to be Added
dl. What additional information, background, or context should be added, or research gaps should be
assessed, to better characterize any potential impacts to drinking water resources from this stage of the
HFWC?
Various data, analysis, and reporting gaps occur within this chapter of the draft Assessment Report. The
EPA should address each of the following gaps as it develops the final Assessment Report:
• What qualifies as a 'spill' is not defined clearly in the draft document. The final Assessment
Report should include a section on requirements for reporting spills, and the EPA should
highlight differences, as they may exist, between state and Federal agencies. For example, the
EPA should describe: (a) whether there is a spill volume below which a report is not required;
and (b) whether a report is required if a spill is contained by on-site mitigation measures, and is
deemed to not reach the 'environment.'
• A primary gap in understanding on the potential impacts of the HFWC on drinking water
involves the requirement for monitoring of water resources, including analysis of the potentially-
affected environmental receptors prior to the initiation of hydraulic fracturing operations.
Industry reports spills but the spill data are not all easily accessible, nor is industry-conducted
monitoring readily available in a convenient electronic format. The reported spill data are likely
a subset of all spills (varying by region, and the definition of what constitutes a spill.) and, when
reported, the spill data may not be easily accessible or may not constitute the needed range of
data to assess the impact on water quality compared to conditions prior to hydraulic fracturing
operations. The SAB recommends that the final Assessment Report include a summary of
current federal, state and tribal monitoring requirements before, during and after hydraulic
fracturing operations, including types of monitoring wells (i.e., construction specifications),
analytical protocols for constituents, and sampling intervals that would provide the data needed
to assess the impact of hydraulic fracturing on water quality (e.g., see Bunn et al. 2012). The
final Assessment Report should also describe the current monitoring that is occurring during
hydraulic fracturing operations and identify gaps in such monitoring.
The EPA should conduct each of the following efforts as it revises the draft Assessment Report:
• The final Assessment Report should identify future research and assessment needs and future
field studies. The agency should outline its plans for collaborating with regulatory agencies and
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research groups (e.g., at universities). The SAB finds that the agency should outline its plans for
conducting prospective studies and other research that the EPA had planned to conduct but did
not conduct.
• A quantitative assessment of the frequency and type of equipment failure (e.g., as described
further in the response to sub-question 5a, subpoint 2, in the body of the SAB Report).
• A quantitative assessment of containment failure.
• An emphasis on the mass of constituents potentially released, not volumes (as indicated in Fig.
5-5).
• An analysis of the mass of constituents released in spills reported.
• A clear distinction between spill volume, frequency, severity; and identification of what are the
target parameters and how will their values be determined.
• A clearer discussion of the chemical additives, including: concentrations, behavior in mixture;
the effects of uncertainties in additive identity on potential severity; and limitations of property
estimation methods.
• A well-documented case of a spill (perhaps an analogue) that is illustrative of actual risk and
consequences.
• Extension of the chapter's analysis to updated versions of FracFocus and state reporting systems.
• An analysis of state response to spills, including: how spills are handled, who responds, the state
and federal required actions on spills, and penalties for not reporting.
• A discussion of the principles of monitoring, with a recognition that specific monitoring
campaigns will of necessity be site-specific.
In addition, once hydraulic fracturing fluids enter the environment, their transport and fate can become
highly complex, costly, and in some cases difficult to assess and remediate. The EPA should update the
chapter's discussion to emphasize efforts to contain and prevent hydraulic fracturing spills.
Also, the discussion in Section 5.8 on fate and transport provides little realistic assessment of the
transport of hydraulic fracturing fluids to a drinking water receptor. The complexities involved in fate
and transport are not covered in depth in Section 5.8. Hydraulic fracturing spills are not monolithic in
type or potential severity, and this section gives the false impression that the transport of spilled fluids
through complex earth materials is well understood. The SAB recommends that the EPA include some
analogue cases that can provide illustrative examples of a spill and its likely fate in the environment. For
example, a spill that would exemplify potential impacts of hydraulic fracturing fluid spills could be
included to illustrate key ideas about environmental fate and transport and link it to the types of
monitoring systems that could be installed to assess and evaluate potential impacts to drinking water
from hydraulic fracturing sites. The SAB also suggests that the EPA consider studies from Superfund
sites or many of the documented cases of leaking underground storage tanks as a source of example
spills that the EPA could consider for such an assessment.
d2. Are there relevant literature or data sources that should be added in this section of the report?
The SAB recommends that the EPA consider the following additional literature sources within this
chapter of the final Assessment Report:
Monitoring: The following references are examples of publications that discuss approaches to
monitoring schemes that are necessarily site-specific. The second reference, a journal, focuses on the
topic:
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• Bunn, A.L., D.M. Wellman, R.A. Deeb, E.L. Hawley, M.J. Truex, M. Peterson, M.D. Freshley, E.M.
Pierce, J. McCord, M.H. Young, T.J. Gilmore, R. Miller, A.L. Miracle, D. Kaback, C. Eddy-Dilek, J.
Rossabi, M.H. Lee, R.P. Bush, P. Beam , G.M. Chamberlain, J. Marble, L. Whitehurst, K.D. Gerdes,
and Y. Collazo. 2012. Scientific opportunities for monitoring at environmental remediation sites
(SOMERS): integrated systems-based approaches to monitoring. U.S. DOE (U.S. Department of
Energy) DOE/PNNL-21379. Prepared for Office of Soil and Groundwater Remediation, Office of
Environmental Management, U.S. DOE, Washington, D.C., by Pacific Northwest National
Laboratory, Richland, WA.
• National Groundwater Association, Groundwater Monitoring and Review, various articles.
Spills: The following are examples of specific reports of spilled liquids. The article written by Gross,
S.A. et al., is referenced within Chapter 5 of the draft Assessment Report; the SAB recommends that the
EPA discuss this publication within Chapter 5.
• Bair, E.S., and R.K. Digel. 1990. Subsurface transport of inorganic and organic solutes from
experimental spreading of oil-field brine. Ground Water Monitoring and Remediation, vol. 10, no. 3,
p. 94 - 105.
• Drollette, B.D., K. Hoelzer, N.R. Warner, T.H. Darrah, O. Karatum, M.P. O'Connor, R.K. Nelson,
L.A. Fernandez, C.M. Reddy, A. Vengosh, R.B. Jackson, M. Eisner, and D.L. Plata. 2015. Elevated
levels of diesel range organic compounds in groundwater near Marcellus gas operations are derived
from surface activities. Proceedings of the National Academy of Sciences 112(43), p. 13184-13189.
October 27, 2015. doi/10.1073/pnas,1511474112.
• Gross, S.A., H.J. Avens, A.M. Banducci, J. Sahmel, J. Panko, and Tvermous, B.T. 2013. Analysis of
BTEX groundwater concentrations form surface spills associates with hydraulic fracturing
operations. J. Air Waste Manag. Assoc. 63(4), p. 424-432.
• New York Times. 2014. Reported Environmental Incidents in North Dakota's Oil Industry. An
interactive database by spill type can be found here:
http://vvvvvv.nvtimes.eom/interactive/2014/l 1/23/us/north-dakota-spill-database.html
Reporting: Although most State databases are not electronically searchable and thus create a substantial
problem in finding and using hydraulic fracturing data, the SAB recommends that Chapter 5 of the final
Assessment Report be revised to include an assessment of state-level reporting efforts, and that the
following references be considered by the EPA in this assessment:
• North Dakota Department of Health. 2015. Reporting requirements for spills can be found here:
http://www.ndhealth.gov/EHS/Spills/
• Groundwater Protection Council. 2014. State Oil and Gas Regulation Designed to Protect Water
Resources. Groundwater Protection Council.
Frequency: the SAB recommends that Chapter 5 of the final Assessment Report be revised to
substantially update the analysis on the relative frequency of chemical mixing spills compared to other
types of spilled liquids. The following reference provides information that may support this analysis:
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• U.S. EPA (U.S. Environmental Protection Agency). 2000. National Water Quality Inventory: 2000
Report. Chapter 6: Groundwater quality. United States Environmental Protection Agency Office of
Water, Washington DC 20460. EPA-841-R-02-001. August 2002.
3.4. Well Injection Stage in the HFWC
Question 4: The third stage in the HFWC is well injection: the injection of hydraulic fracturing fluids
into the well to enhance oil and gas production from the geologic formation by creating new fractures
and dilating existing fractures. This is addressed in Chapter 6.
a. Does the assessment clearly and accurately summarize the available information concerning
well injection, including well construction and well integrity issues and the movement of
hydraulic fracturing fluids, and other materials in the subsurface?
b. Are the major findings concerning well injection fully supported by the information and data
presented in the assessment? Do these major findings identify the potential impacts to
drinking water resources due to this stage of the HFWC? Are there other major findings that
have not been brought forward? Are the factors affecting the frequency or severity of any
impacts described to the extent possible and fully supported?
c. Are the uncertainties, assumptions, and limitations concerning well injection fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water resources
from this stage of the HFWC? Are there relevant literature or data sources that should be
added in this section of the report?
Chapter 6 presents a discussion on well injection, in particular the injection of hydraulic fracturing fluids
into the well to enhance oil and gas production from a geologic formation by creating new fractures and
dilating existing fractures. The chapter examines fluid migration pathways within and along hydraulic
fracturing production wells, includes an overview of well construction, and discusses hydraulic
fracturing fluid movement including fluid migration associated with induced fractures within subsurface
formations. It also provides an overview of subsurface fracture growth, discussion on the migration of
fluids through pathways related to fractures/formations, and a chapter synthesis of major findings,
factors affecting the frequency or severity of impacts, and uncertainties.
3.4.1. General Comments
This is a dense and technically complex chapter. The EPA should include more accurate and frequent
illustrations, photos, maps, and diagrams in this chapter to help the reader better understand the complex
issues and technologies discussed.
A key aspect of assessing impacts to drinking water resources from the well injection stage of hydraulic
fracturing operations is well construction and operations that are protective of drinking water resources,
location and characterization of abandoned/orphaned oil and gas wells, and isolation of potable water
from hydraulic fracturing operations. The agency should recognize in the final Assessment Report that
the following are essential activities for the protection of drinking water resources during the well
injection stage of hydraulic fracturing operations: inspection, testing and monitoring of the tubing,
tubing-casing annulus and other casing annuli; and monitoring and testing of the potable groundwater
aquifers through which the tubing, tubing-casing annulus and other casing annuli pass.
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In Chapter 4 of the draft Assessment Report, the EPA used text boxes and case study summaries to
illustrate concepts which may be new or unknown to the public. The SAB recommends that the EPA
include similar boxes and summaries in Chapter 6, and perhaps other chapters as well, to improve the
explanation to the reader on what has happened and why, and to help address concerns that have been
raised by the public. Furthermore, the chapter should include more information on borehole
construction, geologic layering and heterogeneities in physical properties, and well integrity issues
presented in language that will be understood by the nontechnical reader.
To better inform the readers on available processes, methods and technologies that can minimize
hydraulic fracturing's potential impacts to drinking water resources, the SAB also recommends that this
and other chapters of the final Assessment Report should summarize the many improvements, changes
or accomplishments that have occurred since 2012 in hydraulic fracturing operations related to the
HFWC, including significant technological and regulatory oversight improvements that have occurred
related to well construction, well integrity and well injection.
Important lessons from carbon capture and storage studies, such as those conducted by and with support
of the DOE, have shown that well construction and integrity issues are a primary concern with potential
releases of constituents into the environment associated with subsurface storage. The SAB notes that
these carbon capture and storage studies have relevance to assessments regarding potential releases from
hydraulic fracturing activities. The SAB recommends that the agency examine DOE data and reports on
risks of geological storage of CO2 to water resources and include relevant information in the Assessment
Report.
3.4.2. Summary of Available Information on Hydraulic Fracturing Well Injection
a. Does the assessment clearly and accurately summarize the available information concerning well
injection, including well construction and well integrity issues and the movement of hydraulic fracturing
fluids, and other materials in the subsurface?
To better characterize any potential impacts to drinking water resources from the well injection stage of
the HFWC, the EPA should further assess available information that will support activities
recommended by the SAB within the responses below to sub-questions 4a, 4b and 4c.
The description of available data and information regarding well construction, injection and well
integrity in Chapter 6 is generally well documented, but is geared toward a professional audience. The
EPA should revise the text of this chapter of the final Assessment Report so that the reader can better
understand the intricacies of hydraulic fracturing well design and of well integrity issues.
The chapter's well construction discussion should discuss federal, state and tribal regulatory oversight
(including recent improvements and developments which have helped make operations safer),
mechanical integrity testing of cement and wells, well integrity testing at the time of initial completion,
and subsequent monitoring after the many fractures are placed.
In Chapter 6, the agency should include meaningful, accurate and properly scaled diagrams and charts to
accompany the text. The relevant appendices linked to this chapter should be expanded to include more
information on well construction, injection and well integrity design. The EPA should strengthen the
chapter's presentation of technical concepts by including clearer geologic illustrations and improved
figures to help the reader understand heterogeneity (e.g., natural fractures, rock properties, and geologic
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layering) of the subsurface. The EPA should also fully explain any acronyms that are being used in this
chapter since the acronyms are often confusing and presented without elaboration.
3.4.3. Major Findings
bl. Are the major findings concerning well injection fully supported by the information and data
presented in the assessment?
b2. Do these major findings identify the potential impacts to drinking water resources due to this stage
of the HFWC?
Most major findings presented by the EPA in Chapter 6 are generally supported by the information and
data provided by the EPA, and the major findings presented by the EPA in this chapter identify many
conceivable potential impacts to drinking water associated with this stage in the HFWC. However, the
EPA should state more clearly the findings of this chapter, and the chapter's conclusions should flow
clearly from those specific findings. Before drawing conclusions on water quality impacts associated
with this HFWC stage, the EPA should:
• Clarify the description of the probability, risk, and relative significance of potential hydraulic
fracturing-related failure mechanisms, and the frequency of occurrence and most likely
magnitude and/or probability of risk of water quality impacts, associated with this stage in the
HFWC;
• Include a discussion of recent state standards for hydraulic fracturing well design, required
mechanical integrity testing in wells, new technologies and fracture fluid mixes, and federal,
state and tribal regulatory standards that have changed, or may have changed, the probability of
risk of water quality impacts associated with this stage in the HFWC; and
• Include an analysis and discussion on hydraulic fracturing case studies and example situations
where impacts may have occurred.
To improve the presentation and identification of major findings in Chapter 6, the EPA should provide a
hierarchy regarding what are the most important first order factors and effects vs. second and third order
factors and effects associated with the potential impacts of hydraulic fracturing well construction, well
integrity and well injection on drinking water resources. For example, the EPA should discuss first and
second order factors and effects regarding the severity and frequency of potential impacts from poor
cementation techniques, hydraulic fracturing operator error, migration of hydraulic fracturing
constituents from the deep subsurface, and abandoned/orphaned oil and gas wells (including likelihood
of impacts, number of abandoned/orphaned oil and gas wells, and plugging issues associated with such
wells). The SAB recommends that the EPA prioritize and improve the discussion of conclusions
regarding frequency and severity of impacts, and describe high vs. low probability of occurrence, and
what the EPA considers high vs. low probability impacts. The EPA should include a conceptual,
summary figure that includes axes of probability vs. impact within this analysis.
On pages 6-56 and 6-57 of this chapter, the EPA includes the following major finding: "Given the surge
in the number of modern high-pressure hydraulic fracturing operations dating from the early 2000s,
evidence of any fracturing-relatedfluid migration affecting a drinking water resource (as well as the
information necessary to connect specific well operation practices to a drinking water impact) could
take years to discoverThe EPA should provide additional information regarding this finding, and
further describe the basis for making this statement.
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Also, the last sentence of the conclusory discussion in Section 6.4.4. on page 6-57 states: "Evidence
shows that the quality of drinking water resources may have been affected by hydraulic fracturing fluids
escaping the wellbore and surrounding formation in certain areas, although conclusive evidence is
currently limited. " The SAB recommends that the EPA revise this sentence since this conclusory
sentence is internally contradictory.
h3. Are there other major findings that have not been brought forward?
While the major findings for Chapter 6 are supported by the information and data and identify many
conceivable potential impacts to drinking water resources, the EPA did not bring forward assessments of
the likelihood and commonality of possible impacts to drinking water resources associated with
hydraulic fracturing well construction, well integrity and well injection. Also, there are several issues
regarding cement and casing, spatial and temporal considerations, and stray gas that are critical to
ensuring hydraulic fracturing well integrity that the EPA should further assess, which are further
described below. The EPA's further assessment on these issues may result in additional major findings
within this chapter of the final Assessment Report.
Cement and Casing
The SAB finds that cement integrity, initially and over time, is critical to ensuring hydraulic fracturing
well integrity, and hydraulic fracturing cement integrity and issues surrounding such integrity have not
been well defined in Chapter 6 of the draft Assessment Report. Also, design principles associated with
hydraulic fracturing cement integrity are absent from the draft Assessment Report and should be
included to help the reader better understand cement integrity.
The highest priority for improving the EPA's hydraulic fracturing cement and casing discussion in the
final Assessment Report is for the EPA to rewrite and better describe recommendations and
requirements for mechanical integrity testing in wells prior to, during and after the hydraulic fracturing
process has been completed. While these tests are mentioned in the footnotes of Chapter 6, the final
Assessment Report should specifically discuss the importance of conducting these tests in the text of
Chapter 6, or highlight these tests in a text box that the EPA could include in this chapter. The SAB
recommends that the final Assessment Report mention that: (a) these tests are vitally important to
conduct to ensure hydraulic fracturing well integrity; (b) that these tests, along with cement bond log
analyses, should be conducted before a well is hydraulically fractured and also on a periodic basis
through the life of the hydraulic fracturing well to ensure hydraulic fracturing well integrity; and (c) if
these tests indicate a compromise of the well integrity, remedial activity should be conducted before
further hydraulic fracturing operations can proceed. The SAB also suggests that the EPA include a
figure in the final Assessment Report that depicts a cement bond log that indicates good cement
bonding, no cement bonding, and partial bonding. The SAB suggests that the EPA consider use of a
diagram published by the Society of Petroleum Engineers on this topic (Society of Petroleum Engineers
2013).
Since the quality, placement and type of cement is critical towards ensuring hydraulic fracturing cement
integrity, the EPA should improve the final Assessment Report's discussion on the various classes of
cements used as well as different types of casings for hydraulically fractured wells. The EPA should
include a diagram that illustrates typical cementation practices both in active as well as in
abandoned/orphaned oil and gas wells. Regarding abandoned/orphaned oil and gas wells, the EPA
should provide a profile diagram of an abandoned well with typical placement of cement, and include
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discussion on the frequency of, and requirements for, cementing of abandoned wells. The EPA should
also describe how abandoned wells of questionable integrity can provide a pathway to freshwater
sources, and note that such wells are abundant, not routinely characterized, and in many instances not
even identified.
The EPA should also include more information on aging hydraulically fractured wells, how wells may
be re-completed (i.e., re-fracturing previously hydraulically fractured wells) and use of acids in old wells
(and whether use of such acids degrades old cement), and include statements on whether these wells and
hydraulic fracturing activities result in potential impacts to drinking water resources. The EPA should
also better describe the use of evaluation methodologies (e.g., cement bond logs, temperature logs,
acoustic and circumferential bond logs, and pressure testing) and limitations of such methodologies in
assessing hydraulic fracturing well cement and casing integrity.
The SAB finds that databases and data exist for cement and casing integrity in hydraulic fracturing, and
while these databases have not generally been readily accessible this situation appears to be improving.
The EPA should note in Chapter 6 the benefits to be gained through industry disclosure and sharing of
specific data on cement and casing integrity to increase transparency on issues associated with this topic.
In order to reduce uncertainties associated with cement and casing characterization in hydraulic
fracturing, the SAB also provides recommendations regarding the well file review under the 'Statistical
Analysis' heading of Section 3.4.4 of this SAB report.
Within Chapter 6 of the final Assessment Report, the EPA should also describe available new research
and technology that has been developed since 2010 with respect to cements, low thermal gradient setting
times, swellable elastomers and flexible cements. The EPA should describe how available and
widespread are the uses of these technologies, whether the availability and use of these technologies
affects the temporal variation of occurrence of problems associated with cement and well integrity, and
whether any, some, or most of the identified impacts associated with cement and well integrity have
been or could be mitigated by such technologies.
The EPA should also better explain how pressure diffusion in karst limestone formations and in porous
zones adjacent to shales can be critical in diffusing migration pathways associated with installation and
cementing practices of hydraulically fractured wells. The EPA should improve the discussion to note
that these pathways are complex and that porous zones can help diffuse pressures. This discussion
should also describe the various difficulties associated with cementing hydraulically fractured wells in
such zones.
The EPA should discuss the potential effects of natural and induced seismicity on cementing integrity
and the challenges of studying this phenomenon.
Furthermore, within Chapter 6 the final Assessment Report, the EPA should avoid use of words such as
"conduits" to describe minute cracks and fissures in rocks, since mechanical discontinuities occur on a
range of scales and very few cracks/fissures are as large-scale as implied by words such as "conduits."
Spatial and Temporal Issues
Within Chapter 6 of the final Assessment Report, the EPA should include additional discussion on how
the manner by which hydraulically fractured wells are completed may affect how gas escapes from the
hydraulic fracturing well, and how methods for hydraulically fracturing a well have improved over time
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to further mitigate such gas release incidences. The EPA should include a summary of temporal and
spatial variations associated with hydraulic fracturing-related gas release incidences that have occurred,
and the SAB concludes that such information would help to address many public concerns on this topic.
The SAB recommends that, at a minimum, the EPA should report the dates of such incidences (which
may be noted on the collected data and from the literature review) so that conclusions regarding
temporal trends may be drawn or inferred.
The EPA describes many timeframes in Chapter 6 but does not adequately differentiate or discuss these
timeframes. The period of fluid injection to fracture the source rock may be hours or days for each
fractured well segment; in contrast, the flow of oil and/or gas back into the well lasts for the entire
production life of the well, which can be many years. Since hydraulic fracturing has a short time
duration (hours/days) and post-fracturing produced water collection and disposal are performed over
many years, the EPA should consider including and discussing a bar graph that summarizes duration of
different events in the "life-cycle" of a well. For example, see the graph suggested by SAB Panel
member Dr. Scott Bair in his preliminary individual Panel member comments for Charge Question 4.1
Such a summary would provide clarity on the difference in the duration of these stresses and the
difference in the duration of fluid flow directions oriented away from and into the well.
The EPA should include information regarding the spatial proximity of wells to each other and to water
sources and to known geologic faults to help the reader better understand the physical situation in which
hydraulic fracturing well injection is conducted. In addition, the SAB notes that statistical information
on hydraulic fracturing well data summaries is generally not available. The recommendations in the
above two sentences can be considered longer term future activity. In addition, the EPA should provide
more information on the three-dimensional nature and aspects of well injection in the HFWC.
Stray Gas
The EPA should expand the stray gas migration discussion in Chapter 6 on techniques that can be used
to identify the source of stray gas such as noble gas tracers, and more clearly describe the pathways for
such migration. While the draft Assessment Report accurately describes the general state of the art of
these techniques, and describes variations in stray gas with respect to different types of oil and gas
production (e.g., coal bed methane), the science of stray gas migration and analysis is described only
briefly and should be rewritten to include greater clarification on the topic. For example, in its
descriptions of situations where hydraulically fractured wells may not be properly cased and cemented,
the EPA should distinguish between fracture-related gas vs. stray gas that may migrate naturally through
formations.
1 See SAB's October 28-30, 2015 meeting website for these posted individual SAB Panel member comments, at the
following website address:
http://YOsemite.epa.gov/sab/sabproduct.nsf/a84bfeel6cc358ad85256ccd006b0b4b/26216d9fbba8784385257e4a00499ea0IQp
enDocument&Date=2015-10-28.
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3.4.4. Frequency or Severity of Impacts
b4. Are the factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
The SAB finds that Chapter 6 could be improved if the final Assessment Report clarified the
probabilities associated with the frequency and severity of impacts to drinking water resources
associated with various stages of the hydraulic fracturing well injection process. The chapter generally
does an excellent job of explaining the possible situations that may occur and result in a release from the
well injection process that may impact drinking water resources. However, the chapter should provide a
more focused discussion on the likelihood, frequency, magnitude, and severity of such impacts. The
text, if not modified, would leave the reader to deduce or make incorrect inferences regarding such
impacts. The EPA should clarify in Chapter 6 what is known about the frequency and the severity of
such impacts, and should not state that the EPA is unable to assess such impacts or severity.
As recommended in the following paragraphs, the EPA should further assess data available to improve
the discussion on likelihood, frequency, magnitude, and severity of such impacts. While the anecdotal
data on this topic are well described and very fully documented within the draft Assessment Report, the
data are not statistical in nature, and therefore conclusions on severity of impact are difficult to assess.
Conclusions as to severity and risk based on such data should be developed after these and other data are
assessed.
Statistical Analysis
Chapter 6 does not quantify the number of impacts described in the literature associated with the well
injection stage of the HFWC. While the draft Assessment Report states that there are inadequate data to
quantify the frequency or severity of such impacts, available literature and research presented in the
draft Assessment Report did uncover a limited number of impacts. In addition, the EPA's Well File
Review that is described in Text Box 6.1 on page 6-6 of the draft Assessment Report statistically
examined a number of well files selected from approximately 24,000 wells. The SAB notes that the EPA
can reduce uncertainties associated with hydraulic fracturing cement and casing characterization by
examining and assessing substantially more than the 327 well files evaluated out of the approximately
24,000 well files total that are referenced in the draft Assessment Report, as a longer-term future
activity, and use this information to help assess the frequency of impacts relative to the number of
hydraulically fractured wells. The SAB also recommends that the EPA conduct full statistical analyses
on such an expanded Well File Review, and develop graphs or tables associated with such analyses. The
recommendations in this paragraph can be considered longer-term future activities.
The SAB recommends that when estimated percentages are quoted from the Well File Review, the EPA
should accompany them with the relevant confidence intervals, and indicate whether they are found in
the text of the Review or are inferred from graphs. The EPA should also discuss whether the relatively
low percentage of horizontal well completions covered by the Review limits its relevance to current
practice.
Distinguishing Sources of Stray Gas
The EPA should distinguish studies that "presume" that impacts are caused anthropogenically, since the
actual causes of such impacts may be natural (fault seepage) or due to historical events (such as releases
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from old, abandoned/orphaned oil and gas wells). The SAB recommends that the EPA rely on
scientifically sound peer-reviewed papers (e.g., Darrah et al. 2014, that is cited in the draft Assessment
Report) that identify sources of migrated gases based on isotopic and compositional analysis of the gas
to identify the actual causes of such impacts, and that do not attempt to eliminate natural pathways based
on assumptions that are not scientifically justified.
Section 6.4.1.3 of the draft Assessment Report describes several cases of documented impacts, and
clarifies that the causes may be inconclusive. The SAB recommends that the EPA describe the
frequency of such impacts relative to the number of wells. Some of these documented impacts were not
documented to have occurred from hydraulic fracturing activities, and the reasons for such inconclusive
documentation should also be described.
The EPA should expand the stray gas migration discussion in Chapter 6 on techniques, such as noble gas
tracers, used to identify the source of stray gas, and as noted earlier, more clearly describe the pathways
for such migration. The final Assessment Report should discuss publications describing cases of such
migration, and evaluate the veracity of conclusions drawn in these studies. The EPA provided a good
discussion on Page 6-2 of the complexity and challenges associated with differentiating stray gas
migration due to hydraulic fracturing activities from numerous potential natural and anthropogenic
processes of gas, and the many potential natural occurring or man-made routes that may exist for such
migration.
The EPA should expand and clarify the discussion on the current use by industry of tracers for injection
fluids, as well as any efforts made by the EPA or other entities to develop tracers, and describe how the
use of tracers might be an approach that could allow assessment of releases of contamination and
interpretation of the source of contamination if it occurs. For example, the agency should summarize
what constituents, metal cations, and isotopes are used currently for chemical and radioactive tracers, the
degree to which tracers are used, where tracers are used, what concentrations are in use, and what
concentrations are measured for these tracers in injection fluids. The EPA should consider the
publication of Warner et al. (2014) in its expansion of discussion on the use of tracers for assessing
potential releases of hydraulic fracturing fluids.
Distinguishing sources and pathways for gas resulting from casing failure, from natural migration in
faults or shallow formations, or from unknown abandoned/orphaned oil and gas wells is typically
difficult, and assessments of source and migration path often result in conflicting expert opinions.
Beginning on page 6-16 in Section 6.2.2.1 in Text Box 6-2, the draft Assessment Report states that new
noble gas and hydrocarbon stable isotope data can be used to further distinguish these sources and
pathways. The SAB finds that clear evidence of the existence of these pathways is needed to make
sound conclusions on those sources and pathways.
It is stated in Chapter 6 that methane occurs naturally in many aquifers and that methane from different
sources (i.e., significantly different formations and/or depths) can often be distinguished isotopically or
compositionally. The text should be modified to clarify that the increase of methane alone in an aquifer
or a nearby, domestic/residential or commercial potable well is not a good indicator of a release from a
hydraulic fracturing well due to the potential release of naturally occurring methane in that aquifer from
pumping or sampling disturbances in the water well. The text should also note that the best method for
confirming cause and effect of methane releases is pre-drilling baseline sampling and post-drilling
sampling of well fluids, combined with use of isotopic and compositional analysis of dissolved gases,
anions and cations and knowledge of the existing or perturbed natural pathways. However, as noted in
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the previous paragraph, interpretation of these data is complicated and often results in conflicting expert
opinions.
Modeling Fluid Flow
The EPA should improve the description and presentation in Chapter 6 of the objectives, designs,
limitations and conclusions of the models and simulations that support analysis of the well injection
stage of the HFWC. The modeling associated with this stage of the HFWC that the EPA conducted as
part of its Assessment Report only studied the injection of fluid over a short period of time under
hydrostatic conditions. The draft Assessment Report should describe additional project modeling work
that is forthcoming. The SAB is concerned that the draft Assessment Report presents a confusing
description regarding how the agency uses actual data (e.g., pressure data, water chemistry data or other
measured parameters) to describe situations where hydraulic fracturing fluids reach drinking water
resources, vs. how the EPA uses modeling predictions of such occurrences to describe these situations.
In the descriptions of the models and simulation results the EPA should clarify that the models are
interpretive and are based on a generic geologic system, generic fracturing stress, a specified hydraulic
gradient, and generic physical rock properties.
Section 6.2.2 of the draft Assessment Report inappropriately uses the word "evidence" with regard to
modeling. In the descriptions of the models for fracture propagation and fluid migration introduced and
discussed in this chapter, the EPA should clarify that these model predictions and results are not
"evidence", and fully and clearly describe the limitations of such models. The EPA should state that the
results from an interpretive model are not presentable as "evidence", and that predictive models must
match natural physical and/or chemical properties measured in the field or in the laboratory. The EPA
should note that the modeling results presented in section 6.2.2 do not represent actual sites, nor do they
contain all combinations of stresses, hydraulic gradients, rock properties, typical geologic settings, and
natural heterogeneity (e.g., fractures, rock properties, and geologic layering). The EPA should clarify
that the models provide possible outcomes that are limited by the assumptions made in design and
implementation of the model. Any reference to a model needs to state the assumptions/limitations of the
model. Predictive models must be validated with measurements/data in order to justify making
predictive simulations. Regarding typical geology, the SAB recommends that the EPA include a
discussion on the importance of understanding the regional geology of an area prior to installing a
hydraulic fracturing well or drilling into a play where hydraulic fracturing will be involved. The brief
overview of regional geologic factors should acknowledge the importance of the physical properties of
the various rock layers (e.g., thicknesses, lithologies, continuity, porosities and permeabilities, fracture
density), the hydrocarbon charge (entry mechanism) and maturation in the reservoir, the overall degree
and complexity of deformation, the extent of separation from base potable groundwater to the objective
producing section, and geothermal and stress field gradients.
In addition, the EPA should provide more or improved figures to illustrate each model/scenario
described in Chapter 6. The EPA should add a description of the modeling assumptions and the
strengths and weaknesses of any modeling parameters, and should make clear that the models described
only provide insights that depend on the quality of input data and the assumed physics and geology.
The chapter's description of natural fractures and the nature of induced vs. natural fractures is brief and
should be rewritten to include more clarity and information. The EPA should gather data abundantly
available from industry, academia and service companies regarding how fractures grow and whether
fractures are likely to reach ground surfaces, and describe such data and analysis in the final Assessment
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Report. Recent research efforts such as those conducted at Colorado School of Mines' Reservoir
Characterization Project (RCP), indicate hydraulically induced fractures generally stay within a very
narrow range above and below the fractured horizon (see Vinal and Davis 2015). In addition, fracture
propagation distances are reported by Davies et al (2012). The SAB notes that Figure 6-1 misleadingly
depicts what appears to be a fresh water zone behind an un-cemented intermediate casing string. The
SAB recommends that Figure 6-1 be revised since it does not depict a realistic scenario of current
industry practice. While Figure 6-5 is a potentially helpful pictorial guide for the well injection stage of
the HFWC, the EPA should describe the complexity of the subsurface geology and well construction
within the chapter in the interpretation of this figure. In addition, Figure 6-5 should be revised to address
the misleading distances and scale and oversimplified geology associated with the figure. The EPA
should also describe a typical industry injection rate and pressure plot for a hydraulic fracturing injection
as a function of time, as related to Figure 6-5, and include the entire fall-off period within this
description.
The SAB notes that hydraulic fracturing simulation and design software, such as STIMPLAN, has been
used in an attempt to create fractures that grow to intersect the base of potable water-bearing units, and
that such simulations were unsuccessful in propagating fractures upward from the target zone to potable
water without assuming geological and geophysical parameters which contradict actual conditions in the
subsurface. Smith and Montgomery (2015) provides useful information on parameters that affect
fracture height growth.
The EPA should acknowledge in the chapter that unidentified abandoned/orphaned oil and gas wells of
questionable integrity can provide a pathway to freshwater sources, and conduct a literature review or
other search to identify the order of magnitude of this problem.
Induced Seismicitv
In addition, the final Assessment Report should include some discussion about what is known regarding
induced seismicity and impacts on drinking water resources associated with HFWC activities. The EPA
should consider the publication by Dillon and Clark (2015) when developing this discussion regarding
the occurrence and causal factors of such events. Detailed discussion of induced seismicity from
hydraulic fracturing-related wastewater disposal and related federal, state and tribal regulatory response
should be reserved for Chapter 8 which is focused on hydraulic fracturing-related wastewater treatment
and disposal. Since 2009 a significant increase in induced seismicity has been noted in Texas,
Oklahoma, Ohio, and other states, and this induced seismicity has been typically linked to high-rate
disposal injection wells and not hydraulically fractured wells. Induced seismicity from well injection for
hydraulic fracturing should be distinguished from induced seismicity associated with hydraulic
fracturing wastewater disposal via Class II deep well injection. The SAB notes that there have been
reports of slightly higher magnitude seismicity at hydraulic fracturing sites (up to Magnitude 4+ in
Alberta and British Columbia as well as in Ohio) (Fischetti 2012; Skoumal et al. 2015; Holland 2011;
Horner et al. 1994; and Perry et al. 2011). The SAB recommends that the EPA include better
documentation within this chapter on the occurrence and any causal factors of such events. For example,
the EPA should include discussion on whether the increased rates or volumes of injection in British
Columbia and Alberta were causal factors for seismicity in those areas, or whether slippage along
natural fractures was the main cause for such seismicity. If fracturing was induced by Class II deep well
injection, the EPA should describe the vertical extent of such induced fracturing and how such induced
fractures compare to fractures caused by hydraulic fracturing activity. The SAB also recommends that
the EPA discuss in the final Assessment Report the importance of continual seismic monitoring at new
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hydraulic fracturing sites or hydraulic fracturing sites that have the potential for elevated seismicity and
impacts on drinking water resources, and provide information on available micro-seismic data and how
such data may impact assessments regarding induced seismicity.
The EPA should provide an overview of the state of seismic monitoring technology and advances of
monitoring technology regarding the detection of seismicity, and provide documentation and monitoring
data available for induced seismicity for hydraulic fracturing and deepwell injection. The trends
associated with such induced seismicity should also be discussed, including whether deep well injection
of hydraulic fracturing-related wastewater is being reduced because of regulatory changes driven by
public concerns about seismic activity and its associated costs, as recently occurred in Oklahoma (Wines
2016). The EPA can consider the recommended activities in this paragraph for longer-term future
activity.
3.4.5. Uncertainties, Assumptions and Limitations
c. Are the uncertainties, assumptions, and limitations concerning well injection fully and clearly
described?
Overall, while Chapter 6 discusses many hydraulic fracturing well injection technologies and scenarios
and possibilities, the EPA should revise the chapter and better describe the uncertainties, assumptions
and limitations of the data and the use of data associated with well injection. In addition, this chapter
should include an assessment on the probability or likelihood of occurrence of impacts to drinking water
resources from well injection. Such an assessment would improve the readers' understanding of
uncertainties associated with this chapter.
The EPA should more clearly describe the uncertainties associated with the probability, risk, and relative
significance of potential hydraulic fracturing-related failure mechanisms, and the frequency of
occurrence and most likely magnitude of water quality impacts associated with the well injection stage
of the HFWC. In particular, the EPA should provide more information on the relative probability of
scenarios presented for potential impacts of the well injection stage of the HFWC. Specific examples of
possible improvements are discussed in the following paragraphs.
The discussion in Chapter 6 on the frequency and severity of impacts associated with the well injection
stage of the HFWC leaves the reader with high uncertainty on the frequency and severity of impacts, and
whether any impacts can happen at any location at any time. The EPA should identify, prioritize and
describe hydraulic fracturing-related issues that have arisen in regard to well injection to reduce
uncertainties and help identify methods to minimize impacts of the well injection stage of the HFWC
and minimize the uncertainties associated with abandoned/orphaned oil and gas wells.
As described above within the response to sub-questions 4b 1 and 4b2, the SAB finds that cement
integrity, initially and over time, is critical to ensuring hydraulic fracturing well integrity, and that the
limited discussion on hydraulic fracturing cement integrity and issues surrounding such integrity within
Chapter 6 increase the uncertainties associated with how cement integrity may affect impacts to drinking
water resources. The EPA should describe the uncertainties surrounding hydraulic fracturing well
cementing integrity. The EPA should also discuss how mechanical integrity testing in wells prior to,
during, and after hydraulic fracturing operations have been completed would lessen the uncertainties
associated with hydraulic fracturing well cementing integrity.
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The SAB also notes that the EPA can reduce uncertainties associated with hydraulic fracturing cement
and casing characterization by examining and assessing substantially more than the 327 well files
evaluated out of the approximately 24,000 well files referenced in the draft Assessment Report. The
SAB also recommends that the EPA conduct full statistical analyses on such an expanded Well File
Review, and develop graphs or tables associated with the results of such analyses. The recommendations
in this paragraph can be considered longer-term future activities.
3.4.6. Information, Background or Context to be Added
dl. What additional information, background, or context should be added, or research gaps should be
assessed, to better characterize any potential impacts to drinking water resources from this stage of the
HFWC?
The EPA should conduct as longer-term future activities the various recommended activities suggested
above within the responses to Charge Questions 4a and 4b to better characterize any potential impacts to
drinking water resources from the well injection stage of the HFWC. Wastewater injection and detailed
discussion of induced seismicity from hydraulic fracturing-related wastewater disposal and related
federal, state and tribal regulatory response should be reserved for Chapter 8 which is focused on
hydraulic fracturing-related wastewater treatment and disposal.
The EPA should also further assess hydraulic fracturing case studies, conduct and assess hydraulic
fracturing water quality measurements, describe new hydraulic fracturing technologies, assess hydraulic
fracturing-related impacts from a systems view, and describe regulatory improvements associated with
hydraulic fracturing, as further discussed below. The recommendations in this paragraph can be
considered longer-term future activities.
Case Studies
The EPA should include a discussion within Chapter 6 on the strengths and weaknesses of available case
studies for well injection activities. The EPA should clarify known data, inferences, and the success of
remedial activities that may have occurred associated with these case studies. The EPA describes two
case studies in the chapter: Bainbridge, Ohio (which was a cement failure and not related to hydraulic
fracturing injection) (Bair et al. 2010); and Kildeer, North Dakota (which was a blowout that happened
coincidentally, but was not related to hydraulic fracturing injection) (Battelle 2013). While these cases
are interesting, they are not directly related to the hydraulic fracturing injection process but are relevant
as part of the greater HFWC picture. The SAB finds that this is an important distinction to be made.
While the EPA describes casing and cement issues causing gas migration behind outer well casings, the
SAB recommends that the EPA discuss publications describing cases of such migration.
Water Measurements
The EPA should discuss the importance of baseline (prior to drilling activity) water quality data
measurements in developing a better understanding of whether impacts from drilling and completion
activities can be identified. The SAB notes that this information is important to understand because it
provides a baseline reference as to water quality and water levels surrounding hydraulic fracturing sites
before HFWC activities occurs. The EPA should identify and describe best practices such as those now
required by the State of Colorado. The SAB notes that pre-drilling water quality and water level data
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will fluctuate with seasonal and other changes in the groundwater flow system. The State of Colorado is
now requiring sampling and measurement prior to and after all oil and gas drilling activity (State of
Colorado 2014). Many oil and gas companies are also implementing such requirements as part of their
own best practices. Shell is one example; see Shell Inc. (undated). In addition, the requirements of
several states for baseline or pre-drilling testing is described in a recent publication (Bosquez et al.
2015). This publication describes the strategies that these states have taken to encourage the collection
of baseline data, which in some states differ from the approach of Colorado. For instance, some states
have a rebuttable presumption that contamination of a domestic well within half a mile of a gas well is
caused by the construction of the gas well. The scarcity of baseline data is mentioned as a limitation in
EPA's draft Assessment, at least in the Executive Summary, but the steps that these states have taken to
require or encourage baseline data collection are not.
As discussed further in the response to Charge Question 7, the EPA should also characterize the toxicity
and mobility of the most important hydraulic fracturing constituents of concern that are injected into
hydraulically fractured wells. An overview of HF fluid constituents with toxicity risks is presented by
Stringfellow et al. (2014). The EPA should also be careful to distinguish between hydraulic fracturing
constituents injected into a hydraulic fracturing well vs. constituents and hydrocarbons that come out of
the hydraulic fracturing well in produced fluids.
The EPA should also discuss in Chapter 6 what is known or inferred about the fate of un-recovered
fracture fluids that are injected into hydraulically fractured wells. The EPA should describe and include
an assessment on where these fluids go if they do not come back to the surface. If this is not possible to
do with any rigor, a description of the differences between millidarcy, microdarcy and nanodarcy
permeability rocks may help the reader understand the variability in fluid recovery under various
geologic scenarios, at least in concept, if not using actual recovery analyses. Two publications with
information on constituents in flowback fluids are Abualfaraj et al. (2014) and U.S. DOE (2011). In
addition, the EPA should describe the challenge of monitoring and modeling the fate of injected fracture
fluids over time.
The SAB acknowledges that there are times when distinction between flowback and produced water is
helpful, especially in considering the temporal evolution of post-fracturing water returned to the surface,
but more specific definitions of the two terms are needed in Appendix J of the final Assessment Report
to clarify the distinction. The EPA should also describe what is meant by produced water and whether
this water comes from hydraulic fracturing and/or from non-HF activities. The EPA should consider
moving Chapter 6's discussion on flowback and produced water to Chapter 7. Further discussion on this
topic is provided in Section 3.5.1 of the body of the SAB report.
Technology
The EPA should include discussions of new technologies that relate to the protection of drinking water
resources and are associated with the well injection stage of the HFWC, including: cement bond logs,
acoustic logs used to "hear" gas movement such as spectral noise testing, cement development
technologies, and monitoring technologies. For example, new cement designs and swellable elastomers
are being used in the hydraulic fracturing industry but are not and should be described within Chapter 6.
In addition, many states require the use of newer "greener" hydraulic fracturing technologies and the
EPA should consider adding a discussion on such technologies to this chapter. A recent publication
highlights some of these advancements in technology (Todd et al. 2015).
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Systems View
The SAB recommends that the EPA undertake, as a longer-term future activity, a systems approach to
identify and list the highest probability and highest magnitude issues associated with the well injection
stage of the HFWC, and distinguish what is naturally occurring and what is induced via oil and gas
development and completion. Such an approach would assess an engineered hydraulic fracturing system
coupled to a heterogeneous natural system, and identify leading causes of failures in the engineered
hydraulic fracturing systems. It would also assess which activities are or are not common to all oil and
gas development, and which problems are uniquely caused by hydraulic fracturing-related activity. The
approach would distinguish which issues arise from the natural earth and which may have been
anthropogenically induced, identify systemic failures, and describe heterogeneities and site-specific
variations in natural systems. The EPA could identify actionable issues within the findings of such a
systems analysis. In addition, the SAB recommends the EPA examine the best practices of some major
oil and gas producers as well as the regulatory requirements by various states to ascertain best practices
in sampling for ground water before and after development and completion activities. Such descriptions
may provide valuable insights in identifying and distinguishing pre-existing water quality issues as well
as water quality issues associated with oil and gas development activity. Such best practices and
analyses would certainly be beneficial on a forward looking basis, but may also help discriminate
between pre-existing and development-induced problems in certain cases where data may have been
captured in the past. The recommendations in this paragraph can be considered as recommendations for
longer-term future activity.
Best Management Practices and Regulatory Changes
The EPA should examine, as a longer-term future activity, federal, state and tribal standards and
regulations that have been implemented with the aim of improving hydraulic fracturing operations
associated with the well injection stage of the HFWC. The SAB recommends that the EPA investigate
the evolution of oilfield and federal, state and tribal regulatory practices that are relevant to hydraulic
fracturing operations, as the evolution of such practices is not described adequately in Chapter 6. The
EPA should describe best management practices associated with federal, state and tribal standards and
regulations related to the well injection stage of the HFWC. The EPA could consider the work
completed on this topic by the American Petroleum Institute (2012). The EPA should also consider
hydraulic fracturing-related standards and regulations within a few key states such as Pennsylvania,
Wyoming, Texas, Colorado and California which all have implemented new hydraulic fracturing-related
regulations since 2012. The EPA could consider the work completed on this topic by the Interstate Oil
and Gas Compact Commission, the State Review of Oil, Natural Gas, Environmental Regulations, Inc.
(STRONGER) organization, the Groundwater Protection Council (GWPC), the American Petroleum
Institute (2012), Freyman (2014), Horner (2013), and Richardson et al. (2013). The EPA should also
more accurately describe changes in such standards and regulations as an "evolution" vs.
"improvement" in these federal, state and tribal regulations. These summaries of best management
practices and regulatory changes need not be an exhaustive analysis of such practices and changes, and
may be prepared as a longer-term, future activity.
The EPA should also consider conducting an assessment on whether new hydraulic fracturing well
construction standards have lowered the frequency and severity of the potential impacts of hydraulic
fracturing well injection on drinking water resources. The recommendations in this paragraph can be
considered as recommendations for longer-term future activity.
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d2. Are there relevant literature or data sources that should be added in this section of the report?
The SAB recommends that the EPA consider the following additional literature sources within this
chapter of the final Assessment Report:
• Abualfaraj, N., Gurian, P.L.; and Olson, M.S. 2014. Characterization of Marcellus Shale flowback
water .Environ. Eng. Sci. 31(9): 514-524. September 2014. doi:10.1089/ees.2014.0001.
• Aly, M., B. Clancey, J. Montgomery, M. A. Bugti, A. F. Ahmadzamri. 2015. Geochemical
Applications for Identifying the Source of Hydrocarbons in Well Annuli. International Petroleum
Technology Conference. IPTC-18309-MS.
• Balashov, V.N., T. Engelder, X. Gu, M.S. Fantle, and S.L. Brantley. 2015. A model describing
flowback chemistry changes with time after Marcellus Shale hydraulic fracturing. American
Association of Petroleum Geologists Bulletin 99(1), 143-154. January 2015. doi:
110.1306/06041413119.
• Blanton, T. L. 1982. An experimental study of interaction between hydraulically induced and pre-
existing fractures, SPE Unconventional Gas Recovery Symposium, 16-18 May, Pittsburgh,
Pennsylvania, 1982. Society of Petroleum Engineers Publication SPE-10847-MS.
• Bosquez, T. IV, D. Carmeli, J. Esterkin, M. Kieng Hau, K. Komoroski, C. Madigan, and M. Sepp.
2015. Fracking debate: the importance of pre-drill water-quality testing. American Bar Association
Section of Litigation. February 18, 2015.
• Browning, R., M. Duffy, D. Gaugler, and P. Jones. 2012. Effectiveness of self-healing cement
additives based on test methodology using simulated cement sheath cracks. Society of Petroleum
Engineers Publication. SPE 161028.
• Bui, B. T. and A.N. Tutuncu. 2013. Modeling the failure of cement sheath in anisotropic stress field.
Society of Petroleum Engineers Publication SPE 167178.
• Cavanagh, P., C.R. Johnson, S. LeRoy-Delage, G.DeBruin, I. Cooper, H. Bulte and B. Dargaud.
2007. Self-healing cement- novel technology to achieve leak-free wells. IADC Drilling Conference
Paper, SPE/IADC 105781,
• Davies, R.J., Mathias, S., Moss, J., Hustoft, S., and Newport, L. 2012. Hydraulic fractures: How far
can they go 1, Marine and Petroleum Geology 2012: 1-6. doi:10.1016/j.marpetgeo.2012.04.001
• De Andrade, J., S. Sangesland, J. Todorovic and T. Vralstad. 2015. Cement sheath integrity during
thermal cycling: a novel approach for experimental tests of cement systems. Society of Petroleum
Engineers Publication. SPE-173871-MS.
• Dillon, D.K. and D. Clarke. 2015. Findings and update on the National Research Council's
Committee on Induced Seismicity Potential of Energy Production and Related Technologies. Oral
presentation given at American Association of Petroleum Geologists Annual Convention &
Exhibition, Denver, Colorado, May 31-June 3, 2015.
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Freyman, M. 2014. Hydraulic fracturing and water stress: Water demand by the numbers.
Shareholder, lender & operator guide to water sourcing. Ceres report. Online URL:
http://www.ceres.org/issues/water/shale-energy/shale-and-water-maps/hvdraulicfracturing-water-
stress-water-demand-bv-the-numbers
Horner, R. 2013. Hydraulic Fracturing Water Issues: Differences in State Regulatory Approaches.
American Society of Mechanical Engineers Open Forum, Washington, D.C. June 19, 2013.
Ingraffea, A.R., Wells, M.T., Santoro, R.L., and Shonkoff, S.B.C. 2014. Assessment and risk
analysis of casing and cement impairment in oil and gas wells in Pennsylvania, 2000-2012.
Proceedings of the National Academy of Sciences 111(30): 10955-10960. July 29, 2014.
www.pnas.org/cgi/doi/10.1073/pnas.1323422111.
King, G., and R.L. Valencia. 2016. Well integrity for fracturing and re-fracturing: what is needed
and why? Society of Petroleum Engineers Publication. SPE-179120-MS.
Landry, G.R.D. Welty, M. Thomas, M. L. Vaughan and D. Tatum. 2015. Bridging the gap: an
integrated approach to solving sustained casing pressure in the Cana Woodford Shale. Society of
Petroleum Engineers Publication. SPE-174525-MS.
Lee, H.P., J.E. Olson, J. Holder, J.F.W. Gale, and R. D. Myers. 2015.The interaction of propagating
opening mode fractures with preexisting discontinuities in shale. Journal of Geophysical Research
120(1), p. 169-181. January 2015. http://dx.doi.org/10.1002/2014JB011358.
Leslie, I., T. Bradley, J. Balamaga, and I. Whyte. 2015. The effect of time on apparent cement
integrity - time lapse logging of cement bond logs. SPWLA 56th Annual Logging Symposium.
Llewellyn, G., F.L. Dorman, J.L. Westland, D. Yoxtheimer, P. Grieve, T. Sowers, E. Humston-
Flumer, and S.L. Brantley. 2015. Evaluating a groundwater supply contamination incident attributed
to Marcellus Shale gas development. Proceedings of the National Academy of Sciences 112(20),
6325-6330. May 19, 2015. doi: 10.1073/pnas. 1420279112.
McDaniel, J., L. Watters, and A. Shadravan. 2014. Cement sheath durability: increasing cement
sheath integrity to reduce gas migration in the Marcellus Shale Play. Society of Petroleum Engineers
Publication. SPE 168650.
Montague, J. A., and G.F. Pinder. 2015. Potential of hydraulically induced fractures to communicate
with existing wellbores. American Geophysical Union Water Resour. Res. 51. September 18, 2015.
doi: 10.1002/2014WR016771.
Olson, J.E., B. Bahorich, and J. Holder. 2012. Examining hydraulic fracture: Natural fracture
interaction in hydrostone block experiments. Society of Petroleum Engineers Publication SPE-
152618-MS, SPE Hydraulic Fracturing Technology Conference, 6-8 February, The Woodlands,
Texas, USA, 2012.
Parmar, J., H. Dehghanpour, and E. Kuru. 2012. Unstable displacement, A missing factor in
fracturing fluid recovery. Society of Petroleum Engineers Publication SPE-162649-MS, SPE
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Canadian Unconventional Resources Conferences, 30 October-1 November, 2012, Calgary, Alberta,
Canada.
Parmar, J., H. Dehghanpour, and E. Kuru. 2014. Displacement of water by gas in propped fractures:
Combined effects of gravity, surface tension, and wettability. Journal of Unconventional Oil and Gas
Resources 5, p. 10-21. March 2014. DOI: 10.1016/j.juogr.2013.11.005.
Richardson, N., M. Gottlieb, A. Krupnick, and H. Wiseman. 2013. The State of State Shale Gas
Regulation. Resources for the Future.
http://www.rff.org/files/sharepointAVorkImages/Download/RFF-Rpt-StateofStateRegs Report.pdf
Shadravan, A., A. Alegria, and Ro Castanedo. 2015. Rheological hierarchy optimization improves
fluid displacement and well integrity - 3 worldwide cases. Society of Petroleum Engineers
Publication. SPE 174773-MS.
Shadravan, A., E. Kias, R. Lew and R. Maharidge. 2015. Utilizing the evolving cement mechanical
properties under fatigue to predict cement sheath integrity. Society of Petroleum Engineers
Publication SPE-175231-MS.
Shadravan, A. J. Schubert, M. Amani and C. Teodoriu. 2015. Using fatigue-failure envelope for
cement-sheath-integrity evaluation. SPE Drilling and Completions Journal, March 2015. p. 68-75.
Shell Inc. Shell onshore tight sand or shale oil and gas operating principles. Undated. Available at
http://www.shell.com/content/dam/shell-new/local/corporate/corporate/downloads/pdf/shell-
operating-principles-tight-sandstone-shale.pdf
Smith, M.B., and C. Montgomery. 2015. Hydraulic Fracturing. Published by CRC Press, p. 59-105.
Stringfellow W.T., J.K. Domen, M.K. Camarillo, W.L. Sandelin, and S.Borglin. 2014. Physical,
chemical, and biological characteristics of compounds used in hydraulic fracturing. J. Hazard.
Mater. 275: 37-54. June 30, 2014. doi: 10.1016/j.jhazmat.2014.04.040.
Todd, B.N., D.C. Kuykendell, M.P. Peduzzi, and J. Hinton. Hydraulic fracturing - safe,
environmentally responsible energy development. 2015. Society of Petroleum Engineers SPE-
173515-MS. For presentation at the SPE E&P Health, Safety, Security and Environmental
Conference - Americas, held in Denver CO, March 16-18, 2015.
Tutuncu A.N. and Bui B.T., 2016, A coupled geomechanics and fluid flow model for induced
seismicity prediction in oil and gas operations and geothermal applications. Journal of Natural Gas
Science and Engineering 29: p. 110-124. doi:10.1016/j.jngse.2015.12.039.
Tutuncu, A.N. and B.T. Bui. 2015. Coupled geomechanical and fluid flow modeling for injection
induced seismicity prediction, 85th Society of Exploration Geophysicists Annual Meeting
Proceedings, SEG2015 SS 2.2, p. 4848-4852.
Tutuncu, A.N. 2014. Microseismic coupled geomechanical modeling for environmental risk
evaluation in shale reservoir developments. International Society for Rock Mechanics Publication
ARMS8-2014-325, ISRM Conference Paper.
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• U.S. DOE (U.S. Department of Energy). 2011. Cost effective recovery of low-TDS frac flowback
water for re-use. U.S. DOE DE FE0000784. Harish R. Acharya, Henderson, C., Matis, H.,
Kommepalli, H., Moore, B., and Wang, H. June 2011. U.S. DOE National Energy Technology
Laboratory, Morgantown, WV. https://vvvvvv.netl.doe.uov/file0o201ibrarv/Research/oil-
gas/FE0000784 FinalReport.pdf
• Vargas Bermea, J. A., S. Taoutaou, K. Olutimehin, M. Vinaipanit, S. Ashraf, G. Segret, J.
Asawakowitkorn, andN. Kongpat. 2015. A case study of flexible/expandable and self-healing
cement for ensuring zonal isolation in shallow, hydraulically fractured gas well, Onshore Thailand.
Society of Petroleum Engineers SPE/IADC-173065-MS.
• Vinal, I, and Davis, T. Surface time-lapse multi-component seismology - a new technology for
hydraulic fracture monitoring? A Montney Shale gas case study. 2015. First Break 33(2): 65-70.
• Warner, N.R., Darrah, T. H., Jackson, R. B., Millot, R., Kloppmann, W., Vengosh, A. New tracers
identify hydraulic fracturing fluids and accidental releases from oil and gas operations. 2014.
Environ. Sci. & Technol. September 28, 2014. dx.doi.org/10.1021/es5032135.
• Wang, W. and A. Dahi Taleghani. 2014. Cement sheath integrity during hydraulic fracturing; An
integrated modeling approach. Society of Petroleum Engineers Publication SPE-168642-MS, SPE
Hydraulic Fracturing Technology Conference, 4-6 February, 2014, The Woodlands, Texas, USA.
http://dx.doi.org/10.2118/168642-MS.
• Wang, L., J.D. Fortner and D.E. Giammar. 2015. Impact of water chemistry on element mobilization
from Eagle Ford Shale. Env. Eng. Sci. 32(4): 310-320. April 1, 2015. doi: 10.1089/ees.2014.0342.
• Warpinski, N. R., J. Du, and U. Zimmer. 2012. Measurements of hydraulic-fracture-induced
seismicity in gas shales. Society of Petroleum Engineers Publication SPE-151597, SPE Prod.
Operations, V. 27, p. 240-252. doi: 10.2118/151597-PA.
• Weijers, L., C. Wright, M. Mayerhofer and C. Cipola. 2005. Developing calibrated fracture growth
models for various formations and regions across the United States. Society of Petroleum Engineers
Publidation. SPE 96080
• Weingarten, M., Ge S., Godt J., Bekins B.A. and Rubinstein J.L. 2015. High-rate injection is
associated with the increase in U.S. mid-continent seismicity. Science 348(6241), p. 1336-1339, June
19, 2015.
• Wilson, B. 2014. Geologic and baseline groundwater evidence for naturally occurring, shallowly
sourced, thermogenic gas in northeastern Pennsylvania. American Association of Petroleum
Geologists Bulletin 98(2), p. 373-394. February 2014. doi: 10.1306/08061312218
• Wines, M. 2016. Oklahoma puts limits on oil and gas wells to fight quakes. New York Times, March
7, 2016. Available at http://www.nytimes.com/2016/03/08/us/oklahoma-earthquakes-oil-gas-
wells.html?rref=collection& r=0
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• Zoback, M.D, Rummel, F., Jung, R. and C.B. Raleigh. 1977. Laboratory hydraulic fracturing
experiments in intact and pre-fractured rock. International Journal of Rock Mechanics and Mining
Sciences & Geomechanics Abstracts 14(2), p. 49-58. March 1977. doi: 10.1016/0148-
9062(77)90196-6.
3.5. Flowback and Produced Water Stage in the HFWC
Question 5: The fourth stage in the HFWC focuses on flowback and produced water: the return of
injectedfluid and water producedfrom the formation to the surface and subsequent transport for reuse,
treatment, or disposal. This is addressed in Chapter 7.
a. Does the assessment clearly and accurately summarize the available information concerning the
composition, volume, and management offlowback and produced waters?
b. Are the major findings concerning flowback and produced water fully supported by the
information and data presented in the assessment? Do these major findings identify the potential
impacts to drinking water resources due to this stage of the HFWC? Are there other major
findings that have not been brought forward? Are the factors affecting the frequency or severity
of any impacts described to the extent possible andfully supported?
c. Are the uncertainties, assumptions, and limitations concerning flowback and produced water
fully and clearly described?
d. What additional information, background, or context should be added, or research gaps should
be assessed, to better characterize any potential impacts to drinking water resources from this
stage of the HFWC? Are there relevant literature or data sources that should be added in this
section of the report?
Chapter 7 presents a discussion on flowback and produced water, in particular the return of injected
fluid and water produced from the target geologic formation to the surface and subsequent transport for
reuse, treatment, or disposal. The chapter examines the volume of hydraulic fracturing flowback and
produced water, including a discussion on data sources and formation characteristics. The chapter also
examines the composition of hydraulic fracturing flowback and produced water, including temporal
changes in flowback composition, total dissolved solids enrichment, radionuclide enrichment, leaching
and biotransformation of naturally occurring organic compounds, similarity and variability of produced
water from conventional and unconventional formations, general water quality parameters, salinity,
organics and metals, naturally occurring radioactive material, and reactions within formations. Chapter 7
also includes a discussion on spatial trends, potential spill impacts on drinking water resources,
produced water management and spill potential, spills of hydraulic fracturing flowback and produced
water from unconventional oil and gas production, and case studies of potentially impacted sites. In
addition, the chapter presents a discussion on roadway transport of produced water and studies of
environmental transport of released produced water, includes a discussion on coalbed methane,
describes transport properties, and a chapter synthesis of major findings, factors affecting the frequency
or severity of impacts, and uncertainties.
3.5.1. Summary of Available Information on Hydraulic Fracturing Flowback and Produced
Waters
a. Does the assessment clearly and accurately summarize the available information concerning the
composition, volume, and management offlowback and produced waters?
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Overall, Chapter 7 provides a clear and accurate summary of the available information concerning
composition, volume, and management of flowback and produced waters. The chapter is generally
encyclopedic in providing a summary of the information that is available concerning chemistry and
volume of flowback and production waters. Since industry practices and available data are changing
rapidly, the EPA should update the chapter with additional information and literature searches. The SAB
identifies several references below for the EPA's consideration.
Some SAB recommendations regarding suggested points of emphasis or improvements in clarity of this
chapter of the draft Assessment Report are noted below and relate to: (1) the organic content of waste
waters, (2) the distinction between flowback and produced waters, (3) the occasional use of tracers by
operators, (4) duration of time needed for well completion versus well lifetime, (5) the proportion of
wells in conventional versus unconventional formations, (6) the relationship of leaks or spills to the
process of hydraulic fracturing itself, (7) the source of salt in waters, (8) best management practices, and
(9) issues related to coal bed methane.
1) The organic content of wastewaters: The water composition data provided in Chapter 7 are limited,
reflecting the fact that few compositional analyses of waters have been published, making analysis of the
available data more complicated. For example, most of the available data on produced water content
were for shale formations and coal bed methane basins, while little data were available for sandstone
formations. One observation from the compilation as presented in the draft Assessment Report that is
notable (and should be addressed) is that the majority of data were for inorganics: only limited data were
available for organics (see, however, Section 7.5.7). The draft Assessment Report summarizes the
organic chemicals reportedly used in hydraulic fracturing fluid. The SAB recommends that the EPA
improve this chapter by further discussion of organic compounds in produced water, and the extent to
which these organic compounds are derived from the shale itself rather than from injections. Some
references are available (e.g., Leenheer et al. 1982; Hayes 2009; Llewellyn et al. 2015; Bair and Digel
1990).
2) The distinction between flowback and produced waters: Within the draft Assessment Report, the EPA
included discussion on the distinction between flowback and produced waters. The SAB acknowledges
that distinguishing these waters may be important to do for some situations or analyses (e.g., for risk
assessment purposes). In the final Assessment Report, the SAB recommends that the EPA include
descriptions of the differences in composition between flowback and produced waters. The SAB
recognizes that produced water over the longer-term more closely resembles formation waters, i.e.,
produced waters represent pre-existing conditions prior to hydraulic fracturing, whereas, in contrast,
flowback over the shorter term includes constituents from injection of hydraulic fracturing fluids (Vidic
et al. 2013; Haluszczak et al. 2013; and Balashov et al. 2015).
In terms of distinguishing between flowback and produced water, the EPA should carefully consider
whether to strengthen the definitions of flowback and produced waters as provided in Appendix J of the
draft Assessment Report (e.g., perhaps to include discussion on the relevance of operational factors,
pressure monitoring, water quality aspects, and other factors that may be associated with these
distinctions). The EPA should also consider providing a description of the differences between
millidarcy, microdarcy and nanodarcy permeability of rocks to help the reader understand the variability
in fluid recovery under flowback vs. produced water phases under these various geologic conditions. In
the more porous and permeable rocks, formation or produced water may come to the surface quickly
within the production casing along with flowback water from the actual HF activity. In less porous and
permeable rocks, flowback water often precedes the flow of formation water into the borehole.
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However, these are not clear and unambiguous distinctions. The SAB also recommends that the EPA
develop, as a longer-term future activity, additional information on changes in produced water chemistry
over time. While this chapter of the draft Assessment Report distinguishes the terms "flowback" and
"produced water" to differentiate the terms in relation to overall well flow, the EPA should more clearly
acknowledge that such differentiation can be difficult or operational at best. This is important in that
releases of produced waters are more likely over time in the production phase of a well (Bair and Digel
1990).
3) The occasional use of tracers by operators: In drilling, perforating, completing or remediating a well,
operators may sometimes use chemical or radioactive tracers to study their technique (Scott et al. 2010).
Indeed, the EPA mentions briefly the use of tracers without much discussion on Page 2-15 ("Post-
fracture monitoring ofpressure or tracers can also help characterize the results of a fracturing job. ")
These tracers allow an operator to either sense the location and depth of injected fluids or cements using
downhole tools (for example with gamma logs for radioactive tracers) or to infer aspects of well
completion. With respect to the latter, an operator may infer where fractures have opened during
perforation stages by monitoring the return of these tracers to the surface. Within Chapter 7 of the draft
Assessment Report, the EPA has comprehensively summarized the available public database of
constituents or metals used for hydraulic fracturing but has not and should summarize what constituents,
metal cations, and isotopes are used for these chemical and radioactive tracers. It is important that the
agency summarize what tracers are used, how much and where tracers are used, what concentrations are
in use, and what concentrations are measured for these tracers in the flowback or produced waters, or are
in use during a cement squeeze. This is especially important for radioactive tracers, given the interest on
the part of the public with respect to the topic of radioactivity in development of unconventional
formations. Radioactive tracers that have been successfully used include antimony, iridium, and
scandium (daughters include tellurium and platinum).
The agency should also clarify that there are two types of tracers in use: minerals naturally present in the
geologic formation or dissolved ions in the brine contained within the formation that can be measured in
flowback or produced waters as a putative "fingerprint" of the formational waters, and elements or
constituents injected into the fracturing fluids intentionally to allow analysis of well completion or
cement squeeze processes. In this paragraph, the SAB is referring to the latter. Also, the SAB
recommends that the EPA expand and clarify the discussion provided in Chapter 7 on the current use by
industry of tracers for injection fluids, as well as any efforts made by the EPA or other entities to
develop tracers, and describe how the use of tracers might be an approach that could allow interpretation
of the source of contamination if it occurs. Within this chapter, the EPA should also explain the
difference between the use of natural tracers vs. induced (injected) tracers and the description of what
isotopes (natural and radioactive) are used as tracers of groundwater, brine, and fracturing fluid
movement.
The State of Pennsylvania Department of Environmental Protection (PA DEP) likely has information
about how often tracers have been used (and where and when) that the EPA could access. Likewise, if
spills of flowback water containing radioactive tracer isotopes occurred in Pennsylvania, then this
information should be available from PA DEP. The EPA should check the online PA DEP database to
see if companies have been cited for Notices of Violation (NOVs). Other states such as Texas and
Colorado would also likely be able to make this information available to the EPA upon request. The use
of tracers in monitoring and evaluation of HF operations is well documented. A list of relevant papers
which cover both the tracer types and uses in HF operations since 2014 is provided in section d2 of this
response.
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4) Duration of time needed for well completion vs. well lifetime: The SAB recommends that the EPA
include more information in Chapter 7 on the length of time it takes to hydraulically fracture a well and
the duration of time over which the flowback is likely to return to the surface. The SAB notes that this is
a pertinent aspect of the distinction between flowback water and production water because the chemistry
of the fluid changes in this time interval. Well completion activities and methods (including hydraulic
fracturing) are used to prepare a well for production following drilling, and the draft Assessment Report
accurately states that hydraulic fracturing of a well takes only a few days, while a well may produce for
decades. However, throughout the chapter the EPA continues to refer to hydraulic fracturing and
lifecycle, and this might imply to a casual reader that the completion process continues through the
lifetime of the well. This lack of clarity within the draft Assessment Report about the duration of time
for well completion could confuse external stakeholders, and should be rewritten. The agency should
also note in the Assessment Report that previously fractured, existing wells may be hydraulically
fractured again in the future.
A list of relevant papers on well fracture time is provided in section d2 of this response. The time
required to fracture a well will vary depending on the type of well. As indicated in the references below,
the unconventional treatments will typically be less than 2-3 hours per stage with many less than 2 hours
per stage. However, since some unconventional wells will have over 30 stages, the total fracturing time
could be well over 24 hours. Some of the conventional wells have very long pump times (12-18 hours)
from some of the lower-permeability gas fields like the Cotton Valley Lime Field in east Texas work
done in the 1980s. However, a number of wells in the Lost Hills and Kerridge fields in California, for
example, are on 1/8 acre spacing and pumping times will be less than an hour for such wells.
A list of relevant papers on the monitoring of well flowback is provided in section d2 of this response.
Flowback times will vary from a few days to well over a month depending on the reservoir type. For
example, reservoirs with very low permeability will typically produce HF flowback fluids very rapidly.
That is, what is going to flowback comes out quickly and the remaining fluid stays in the reservoir.
Conventional higher permeability reservoirs will typically require longer flowback monitoring times.
5) The proportion of wells in conventional versus unconventional oil/gas plays and oil/gas fields, and the
proportion of conventional versus unconventional wells: Another important aspect which the draft
Assessment Report does not make clear is the comparison of conventional to unconventional wells with
respect to water production. Some information is summarized in one paragraph (Section 7.5.1). In
relation to the number of hydraulically fractured wells drilled in the United States, the SAB recommends
that the EPA describe the percentage of hydraulically fractured wells installed in unconventional as
compared to conventional oil/gas plays and oil/gas fields.
While unconventional wells have been the focus of the public and the media, the EPA should also
describe how much hydraulic fracturing is occurring in conventional versus unconventional wells. In
addition, the EPA should describe how much wastewater is produced for each type of hydraulic
fracturing well when considered across the entire United States. This information is important to
describe, since some reports note that "up to 95 percent of new wells drilled today are hydraulically
fractured"2. This recommendation regarding consideration across the entire United States can be
considered a longer-term future activity.
2 See the U.S. Department of Energy's Office of Fossil Energy website on this topic at http://energy.gov/fe/shale-gas-101
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6) The relationship of leaks or spills to the process of hydraulic fracturing itself: Chapter 7 discusses
surface releases during hydraulic fracturing as a potential area of interest with respect to drinking water
resource impacts. The final Assessment Report should clarify whether fluid leaks through surface outer
well casings have any unique association with, or can be caused by, hydraulic fracturing. Surface
releases are most likely to occur during the production phase of a well, as opposed to the hydraulic
fracturing process. After production commences, hydrocarbons and water are separated, and the
produced brine may be pumped or trucked to a salt water disposal well (Class II injection well). While
all surface lines are subject to leaks, the EPA should discuss whether and how hydraulic fracturing
potentially impacts the frequency or severity of these surface line leaks. The draft Assessment Report
mentions several times in Chapter 6 that pressure cycling of wells can impact cement seals, and the EPA
should discuss whether or not these effects on cement seals result in impacts to hydraulic fracturing
wastewaters or change the likelihood of leaks as discussed in this chapter. The EPA should discuss the
potential effects of natural and induced seismicity on wellbore integrity and the challenges of studying
this phenomenon. Also, since it has been reported that the volume of water produced per unit of gas is
less in an unconventional as compared to a conventional well (Vidic et al. 2013), the EPA should
discuss whether impacts to drinking water resources are fewer for unconventional as compared to
conventional hydraulically fractured wells. The PA DEP likely has information on this topic that the
EPA could access, and Brantley et al. (2014) also summarizes some of this information. Also, the
percentage of leakage from tens of thousands of horizontal hydraulic fracturing wells in Oklahoma and
Texas were surveyed in Bachu and Valencia (2014). In addition, since line age and corrosion are factors
in developing leaks, the EPA should describe whether leakage rates are smaller for unconventional wells
because the hydraulic fracturing facilities are generally newer, and whether the materials being used
today are more or less subject to corrosion and breakage than those used in the past (i.e., whether
material selection is a factor positively or negatively affecting the frequency and volume of leaks and
spills). All of these recommendations regarding the relationship of leaks or spills to the HF process can
be considered a longer-term future activity.
7) The source of salt in produced water: The draft Assessment Report emphasizes (from Blauch et al.
2009) that the exceptionally high concentrations (> 100,000 mg/1 TDS < 350,000) of dissolved salts
measured in produced waters and in naturally occurring deep-basin brines are derived from dissolution
of halite and other evaporite minerals in the target shale. The SAB suggests that the EPA rewrite this
discussion, since this emphasis does not generally describe/explain the general presence of high
concentrations of dissolved salts in produced waters (since halite and associated evaporite minerals are
not found in all or most shales). The SAB notes that while some sedimentary basins may contain
subsurface halite layers that chemically interact with the exceptionally slow movement of deep-basin
fluids, the high concentrations of dissolved salts are largely derived from brines that entered the target
formation or in the surrounding formations including evaporite beds that may be present in the basin but
not necessarily in the target formation itself. Given that the Marcellus Shale in New York, Pennsylvania
and Ohio, and the Utica Shale in Ohio are approximately 400 million years old, diffusion of metal
cations from overlying and/or underlying evaporite layers into the target shales is possible. In addition,
on lines 25 and 26 of Page 7-16 the EPA does not comprehensively list causes of increasing solutes
because the increase in the dissolved salt content of production waters with time could be attributed to
transport of brine from small pores in the shale into the induced fractures. Alternately, the increase could
be related to the increasing percentage of deep formation waters (natural brines) moving back to the
lowered production pressures in the well after the hydraulic fracturing process is completed. A paper
describing a mass balance calculation on the brine salts for production wells in the Marcellus Shale
showed a proof of concept for how dissolved salts enter the production water and why it changes with
time (Balashov et al. 2015). The EPA could cite the Balashov et al. (2015) paper in the discussion
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provided on page 7-7, Section 7.3, and on Page 7-26, Section 7.4.1, lines 3-16 of the draft Assessment
Report.
8) Best management practices: Chapter 7 provides a broad, albeit somewhat dated, overview, but should
provide more details that would provide a reader enough information to understand best management
practices used by industry associated with the flowback and produced water stage of the HFWC. These
best management practices include regulatory requirements around secondary containment, reporting,
and remediation activities associated with hydraulic fracturing spills. The SAB finds that if the final
Assessment Report provided more clarity regarding regulatory and industry response to spills, the reader
would be better educated on the overall approach of the industry and its regulators towards these spills.
Further investigation of regulatory and industry response to spills can be a longer-term future activity.
Some relevant papers on best management practices for HF flowback and produced water, and
regulatory requirements for secondary containment are provided in section d2 of this response. This
summary of best management practices need not be an exhaustive analysis of such practices. The EPA
may develop this summary as a longer-term future activity.
9) Issues related to coal bed methane: On Page 7.1.2, Produced Water, Page 7-13, Lines 12-16 of the
draft Assessment Report, the EPA should note that coal bed methane (CBM) wells produce more water
than hydraulically fractured wells because these water-saturated coals, which are the target zones of
CBM wells, are usually part of an extensive but shallow unconfined aquifer system. As CBM wells are
pumped, some amount of pore de-saturation occurs. In contrast, fluids in deep organic shales and other
tight gas formations essentially occur in highly confined aquifers (i.e., reservoirs) in which all pores are
saturated with fluids. As a result, the pores in these deep reservoirs never de-saturate; they are always
filled with some type of fluid (oil, water, gas, brine). The SAB recommends that the EPA include these
distinctions within the final Assessment Report since such distinctions impact the quantity and quality of
hydraulic fracturing waters that are produced during hydraulic fracturing operations.
3.5.2. Major Findings
bl. Are the major findings concerning flowback and produced water fully supported by the information
and data presented in the assessment?
While the major findings, found in Section 10.1.4, are generally supported by the information and data
presented in the assessment, the major findings should be more explicitly quantified and clearly
identified within the chapter itself. The SAB notes that while it is difficult to find where major findings
are summarized in this chapter, the SAB assumes that the major findings are listed in Section 10.1.4 and
Text Box 7-1.
An example of a finding that is described but not adequately highlighted in the draft Assessment Report
is the following: spills of wastewaters from oil and gas development have happened and have affected
drinking water resources. While the SAB concurs with this statement, the EPA should place this
statement in context by also describing the timeframes needed to remediate surface or groundwater to
pre-existing conditions (e.g., National Research Council 2013). This general description and information
is important to include within the final Assessment Report since spills into aquifers are harder to
remediate than spills into surface water. As written, the draft Assessment Report leads a reader to
believe spills and leaks create permanent impacts. As mentioned elsewhere within the draft Assessment
Report, the EPA should support this statement with statistical data as much as possible.
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As discussed in the SAB response to Charge Question 5a, Chapter 7 of the draft Assessment Report is
generally well written and clear. It has the tone of an impartial review and is very encyclopedic,
especially up to Section 7.7 and page 7-30. In this regard, the chapter does a very good job answering
the question, "What is the composition of hydraulic fracturing flowback and produced water, and what
factors might influence this composition?" The SAB notes, however, that only the last 16 pages of the
chapter are devoted to analysis and discussion of potential impacts, modes of impacts, and analysis of
related data, and the SAB finds that these data are presented in encyclopedia format without
interpretation and analysis. In this regard, the SAB finds that the EPA did not adequately synthesize the
implications of the data to emphasize what is important in summarizing the findings to answer the
question, "Are the factors affecting the frequency or severity of any impacts described to the extent
possible and fully supported?" The SAB also finds that the EPA presents a significant amount of
information in Chapter 7 but provides very limited analysis of this information.
b2. Do these major findings identify the potential impacts to drinking water resources due to this stage
of the HFWC?
Chapter 7 identifies the potential impacts to drinking water resources due to this stage of the HFWC but
does not emphasize certain aspects of the system sufficiently.
While the draft Assessment Report provides an overview of fate and transport of spilled liquids and the
various components necessary to evaluate migration of a spill (i.e., amount of material released, timing
of the release, response efforts, timing of response measures, soils, geology, and receptors), it
emphasizes the horizontal and vertical distance between spill and receptor without adequately indicating
that certain subsurface geologic conditions and hydraulic gradient scenarios in the shallow subsurface
can allow fluids to migrate a considerable distance from the point of release. For example, page 7-48
notes that: ".. .impacts to drinking water systems depend on proximity." In fact, researchers have
identified some cases where constituents (both tracers intentionally spilled on the land surface for
research (Brantley et al. 2014) and contaminants unintentionally spilled on the land surface or leaked
from a borehole (Sloto et al. 2013; Llewellyn et al. 2015) entered fractures and moved several
kilometers into aquifers. While such long-distance travel incidents may have been rarely reported (Bair
and Digel 1990; Llewellyn et al. 2015; Vidic et al. 2013), the final Assessment Report should describe
the occurrence, frequency and severity of long-distance travel events, or outline a plan for such an
assessment as a future activity, and recognize that such events could occur.
Also, the draft Assessment Report does not provide sufficient emphasis on the importance of fractures,
bedding planes, and faults in the subsurface. For example, these heterogeneities can act as
discontinuities in the subsurface flow regime, and this should be discussed on lines 30-32 on page 7-42
of the final Assessment Report, and the chapter should note that if hydraulic fracturing fluids spill into a
fractured reservoir, the constituents associated with the release could migrate long distances. Likewise,
the final Assessment Report should note that if a hydraulic fracturing spill were to enter unconsolidated
sediments, migration of the constituents associated with this spill could be observed over a considerable
distance. While the draft Assessment Report appropriately emphasizes large volume spills of long
duration, the importance of small volume spills in specific types of areas (e.g., ridgetops with joints that
interconnect in subsurface) should also be discussed because hydraulic fracturing constituents could
travel into drinking water resources (Llewellyn et al. 2015). Thus, the final Assessment Report should
clarify that long-distance travel of hydraulic fracturing constituents is possible, may have been rarely
reported in the published literature, and can usually be prevented with adequate management practices.
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A few additional publications on long-distance travel of HF constituents are provided in section d2 of
this response.
The SAB also finds that portions of the modeling summary provided in this chapter are misleading as
the modelled subsurface did not include natural geologic heterogeneities and discontinuities found in the
rocks in all sedimentary basins. The SAB concludes this portion of the modeling exercises is unrealistic
because preferential flowpaths in the subsurface are generally important in relation to contaminant
mobility. Likewise, other interpretive modelling cited in the draft Assessment Report (Myers 2012) is
also misleading as it over-emphasizes and over-simplifies highly permeable, geologically unrealistic,
subsurface heterogeneities (e.g., the model grid provides for continuous fractures from the target zone to
the land surface which is geologically unrealistic). The role and characteristics of heterogeneities such as
hydraulic gradients, fractures, faults, and bedding planes in the movement of subsurface fluids should be
explained and emphasized in the final Assessment Report as well as the differences between the results
of interpretive models vs. predictive models. Two examples of interpretive models provided in this
chapter of the draft Assessment Report should be counterposed and explained as endmembers in this
regard. For example, the EPA could directly compare the two modeling examples and explain why one
study concluded that contamination could occur within a very short time period, whereas the other
concluded such contamination was unlikely. In essence, these contradictory conclusions are related to
the simplifying assumptions underlying the two models: the EPA should clarify these assumptions and
comment upon the state of knowledge underlying such assumptions and the veracity of the assumptions.
As mentioned in the response to Charge Question 5a, during drilling, perforating, completing or
remediating a hydraulic fracturing well, operators may sometimes inject chemical or radioactive tracers
to study their technique (Scott et al. 2010). Indeed, the EPA mentions briefly the use of tracers without
much discussion on Page 2-15 of the draft Assessment Report, noting that "Post-fracture monitoring of
pressure or tracers can also help characterize the results of a fracturing job. " The SAB recommends
that the EPA address questions related to the use of injected tracers in Chapter 7, particularly since the
public has expressed repeated interest in the topic of radioactivity in the waters associated with oil/gas
development. For example, the EPA should assess and discuss whether there have been any reports of
spilled liquids or leaks of radioactive tracers associated with hydraulic fracturing operations.
h3. Are there other major findings that have not been brought forward?
Chapter 7 did not bring forward all the major findings associated with the flowback and produced water
phase of the HFWC. The agency should also include additional major findings associated with the
effects on drinking water resources of large spill events that escape containment, and sustained,
undetected leaks. This over-arching observation would be useful to external stakeholders and the general
public, and it is important to state this as a major finding since most of the chapter reads like an
encyclopedia. In this regard, the EPA should also discuss specific areas of this phase of the HFWC that
need improvement and that could help to reduce the number of actual spills, leaks, and releases
associated with hydraulic fracturing. For example, the SAB recommends that the EPA consider
including discussion on whether hydraulic fracturing leaks or impacts could be diminished in number or
severity through closer regulation of the construction practices for hydraulic fracturing-related
containment areas that are described on Page 7-35, line 29 of the draft Assessment Report, through
increased monitoring of hydraulic fracturing activities, or through additional or new hydraulic fracturing
technologies designed to reduce or avoid blowouts.
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Another major finding that Chapter 7 does not sufficiently emphasize relates to how assessments are
conducted after releases of constituents from hydraulic fracturing operations occur to the environment.
The EPA should provide additional context in this chapter of the final Assessment Report concerning
how these assessments are conducted, what information is collected, how that information is provided to
external stakeholders, and what improvements could be offered in this process.
The EPA summarizes a number of steps that are needed to study a suspected impact on pages 7-35 and
7-36 of the draft Assessment Report. This discussion clearly describes how difficult it is to assess and
determine causation of impacts when a hydraulic fracturing incident occurs related to contamination of
groundwater, especially for subsurface leaks, mostly because the requisite data can be difficult and
costly to gather for such attribution. Furthermore, impacts in the subsurface can be very difficult and
costly to remediate. To help assess these issues, the SAB recommends that the EPA add a discussion on
the implications for the use of tracers during drilling or hydraulic fracturing, and also on implications for
the use of nonbiodegradable constituents associated with hydraulic fracturing operations.
Overall, while the draft Assessment Report emphasizes differences in hydraulic fracturing flowback and
produced waters from site to site, the EPA should assess and discuss generalizations of commonalities
among such waters in the final Assessment Report. The EPA should summarize what chemistry is
generally and most commonly observed in hydraulic fracturing waters, for both organic and inorganic
compounds. Such a "generalized water chemistry" would assist in efforts to evaluate potential health
risks associated with such waters. Some of this work could be considered as recommendations for
longer-term future activity, but the final Assessment Report should include some discussion of general
observations regarding flowback and produced water chemistry.
3.5.3. Frequency or Severity of Impacts
b4. Are the factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
While Chapter 7 of the draft Assessment Report provides support for observations made regarding
impacts that are described, the chapter does not describe the factors affecting frequency or severity of
impacts to the extent possible, as described further below.
Chapter 7 summarizes many types of incidents and refers to case studies that describe leaks and spills,
but the draft Assessment Report could be improved by providing additional detail on the extent and
duration of the impacts, including the following, most of which will require longer-term future activities
to address fully:
• The degree to which spills and releases impact drinking water supplies.
• Whether the waterway was severely impacted after a hydraulic fracturing spill or leak.
• The length of time the impact affected a surface or groundwater system.
• The spill types or volumes that are most deleterious to waterways or groundwaters.
• Outcomes: Are most or all spills cleaned up quickly with little impact?
• Whether even the larger spills had significant, long-term impact.
• Whether many or most hydraulic fracturing spills are contained within standard secondary
containment barriers.
Without such information, the reader is left to assume that all spills are impacting soil/groundwater/
surface water. As one example, the chapter's discussion of the Penn Township, Lycoming County, PA
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incident on page 7-37 of the draft Assessment Report confirms that the impact was temporary, noting:
"By January 2011, stream chloride concentrations had dropped below the limit established by
Pennsylvania's surface water quality standardsThe EPA should describe whether any long-term
impacts were observed regarding this incident. Further, within the EPA discussion on the Leroy
Township, Bradford County, PA event in the draft Assessment Report, while the EPA described that
localized surface water impacts were reported, the EPA should discuss whether long-term effects were
reported for the potable water wells.
To understand the likely probability of releases to surface water or groundwater from hydraulic
fracturing activities, the final Assessment Report should quantify in text and in a figure the frequency of
the different types of release events, including whether the spilled hydraulic fracturing material impacts
groundwater or surface water. While the EPA collected a large amount of information about hydraulic
fracturing wastewaters, it should evaluate the data and make tables and figures that concisely summarize
the collected data. The EPA should conduct a statistical analysis on these data, perhaps using statistical
tools of analysis for sparse datasets. For example, while Chapter 7 provides a good identification and
description of the sources for flowback and produced water spills, leaks, and releases, it would be very
helpful if the EPA clarified the text by summing up these types of release events from each section
together through the use of statistics.
In addition, while the draft Assessment Report provides a number of local statistics from specific
studies, these statistics should be summarized in the conclusion Section 7.8.4. For example, the EPA
should specifically note the following within Chapter 7: X number of wells were drilled in the US, Y
number of these wells were hydraulically fractured, and Z number of spilled liquids were reported. In
addition, while Chapter 7 refers back to Chapter 5 (Text box 5-14) for spill rate data and this is
described in text on page 7-33, lines 10 through 21, the chapter should include further summary
evaluation of these data. The data should be shown in easily interpreted figures - perhaps histograms - to
illustrate the size of leaks as well as frequency. Furthermore, to better understand the significance of
releases from hydraulically fractured wells, the EPA should assess, as a longer-term future activity, the
statistical difference between the number of releases for wells completed with hydraulic fracturing
versus those that were not completed with hydraulic fracturing for a specific time period or region.
Furthermore, the EPA should discuss the important finding that half of the 457 reported spills were for
1000 gallons or less of spilled fluids, and that these 457 reported spills were a lower bound of the
number of spills. In addition, the EPA should describe the composition of the spills, to the extent that
data are available. The finding that half of the 457 reported spills were for 1000 gallons or less of spilled
fluids should also be described through an illustration in addition to text. For example, a professional
basketball court is 94 feet long and 50 feet wide. If a 1000 gallon spill occurred and was contained
within that area, it would be about 19 inches deep. The EPA should summarize the number of spilled
liquids in absolute numbers and also in context relative to the number of wells drilled, truck trips, and
pipelines miles.
The EPA should, as a longer-term future activity, also develop figures or tables that summarize the
temporal and spatial scaling associated with statistics of spilled liquids/leaks/contamination events. For
example, the draft Assessment Report notes that the truck accident rate is low and the likelihood of
spilled liquids related to trucks is low, but does not note that truck spills could have important impacts in
a small local area. The final Assessment Report should recognize the potential for significant local
effects and consider this spatial scaling issue throughout the Report when it discusses conclusions
associated with hydraulic fracturing spills, leaks, and contamination events. It is important for the public
to understand why personal experience may differ from broad average observations, and that while not
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all oil/gas development sites are problematic, some oil/gas development sites have been problematic in
the past. For these reasons, the EPA should clarify through longer-term future work the spatial and
temporal aspects of these hydraulic fracturing spills, leaks, and contamination events. The SAB also
notes that clarification of the subtleties of this spatial and temporal scaling would help industry and the
reader better understand the relative frequency and significance of hydraulic fracturing-related problems
in a given area.
Chapter 7 of the draft Assessment Report makes several statements that are so general that the
statements have little meaning. For example, page 7-46 of the draft Assessment Report notes that:
"Conclusive determination of impacts to water resources depends on commitment of resources to the
implementation of sampling analysis and evaluation strategies. " It would be more useful if the EPA
synthesized the available information and described specifically what evaluation strategies and sampling
analysis is needed to provide a conclusive determination of impacts. The EPA should note, for example,
whether baseline data are needed to understand the impacts associated with spilled material.
3.5.4. Uncertainties, Assumptions and Limitations
c. Are the uncertainties, assumptions, and limitations concerning flow back and produced water fully and
clearly described?
While the EPA acknowledges uncertainties in the information presented in Chapter 7, the EPA should
examine these uncertainties in more depth, as a longer-term future activity. The uncertainties described
by the EPA in this chapter provide sufficient detail to provide approximate, general indications of some
risks associated with the flowback and produced water phase of the HFWC. However, the EPA should
provide more information on uncertainties associated with calculating risks from contaminants in
hydraulic fracturing waters (e.g., uncertainties associated with organic contaminants such as benzene
commonly present in produced waters).
In addition to deeper examination of uncertainties, the EPA should summarize approaches that could be
used to reduce these uncertainties and help protect drinking water resources. The EPA should provide a
section outlining the additional information that is needed to more completely understand the risks and
approaches that can be taken to control these risks associated with exposure to hydraulic fracturing
waters.
Chapter 7 identifies data gaps, especially with respect to baseline conditions and with respect to
individual incidents. However, the chapter should clarify if the gaps are present because the data are
non-existent or not easily (i.e., electronically) available. The draft Assessment Report should clarify if
needed data are available but not online publicly, or are not in a format that is easily scrutinized. For
example, the EPA should discuss whether the research team found electronically available data that
might be useful for analysis of water quality impacts, and whether the EPA was unable to provide
resources to collect these data into a database format. The EPA should more explicitly describe issues
surrounding the availability or lack of availability of data, including reasons for any lack of data
availability. This chapter should also describe what improvements have been or are being made by
regulatory agencies to improve database systems which provide more information on operational
activities associated with the oil and gas industry, and recognize that states have made considerable
advancements in electronic database systems that allow for increased reviews and assessments by
external stakeholders.
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3.5.5. Information, Background or Context to be Added
dl. What additional information, background, or context should be added, or research gaps should be
assessed, to better characterize any potential impacts to drinking water resources from this stage of the
HFWC?
As described further below, the EPA should provide more information in Chapter 7 on radionuclides in
wastes, bromide concentrations in hydraulic fracturing-related wastewaters and in surface waters, best
management practices (BMPs) for surface impoundments, and the natural occurrence in subsurface
brines, to the extent that data are available. The EPA should investigate the radionuclide issue in greater
depth as a longer-term future activity, including review of the new Pennsylvania Department of
Environmental Protection research.
Within the final Assessment Report, the EPA should increase the emphasis and better explain the
radioactive nature of some wastes produced during hydraulic fracturing operations. Many public
comments on the draft Assessment Report raised these concerns, and the EPA should expand the
discussion of the importance or possible impacts related to radioactivity within this chapter. While most
of the radioactivity derives from the geologic formation itself, radioactive tracers are sometimes
injected. As mentioned specifically in the response to Charge Question 5a, the final Assessment Report
should specifically and carefully address the use of radioactive tracers during well completion or
remediation. The EPA should also address radioactivity in shale cuttings as part of the assessment of
potential impacts within the final Assessment Report, even though such cuttings are related only to
hydraulic fracturing drilling.
Chapter 7 and Appendix E of the final Assessment Report should amplify discussion on the ion ratio of
CI/Br in flowback and produced water. The SAB notes that bromate is used in fluids used during HF
stimulation treatment. As discussed further in the Charge Question 6 response, significant releases of
bromide from hydraulic fracturing operations to surface or groundwaters subsequently become part of
intake water at downstream drinking water treatment plants and upon disinfection can result in
concentrations of brominated organic compounds that are potentially deleterious to human health
(Wilson and VanBriesen 2012) due to the formation of disinfection by-products (DBP). The EPA should
note that dissolved bromide generally comes from pore fluids that have dissolved bromide minerals in
the rock into which hydraulically fractured wells are drilled, and discuss whether a bromide salt is ever
added as an injection constituent. The final Assessment Report should also more consistently use the
terms "bromine" to refer to the element and "bromide" to refer to the metal ion. In some places the draft
Assessment Report refers to "bromine" whereas in other places the draft Assessment Report refers to
"bromide." The EPA should check that the terms are used appropriately, in each case referring to the
relevant chemical form for the particular context. The same applies to the use of chlorine and chloride,
and iodine and iodide.
The EPA should, as a longer-term future activity, also assess iodide in the same manner as bromides as
recommended in the above paragraph, even though the draft Assessment Report provides very little data
on the presence of iodide in flowback or produced waters. The SAB notes that iodate is not used during
HF operations. Since iodide also reacts with some oxidants to produce DBPs at downstream drinking
water plants, and recent evidence shows that brominated and iodinated DBPs are more cyto- and geno-
toxic than the chlorinated analogs (Plewa and Wagner 2009; and Richardson et al. 2014), information
about iodide in hydraulic fracturing-related wastewaters should be amplified in the final Assessment
Report. The ratio of dissolved Cl/I in table E-4 is around 5000/1, which is much lower (i.e., more iodide)
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than the ratio in seawater, which is 35,000/1. The EPA should discuss why iodide is more concentrated
in flowback and produced water relative to chloride than seawater. In addition, the final Assessment
Report should discuss the degree to which flowback and produced water contains bromate, chlorate,
perchlorate or iodate. All of these chemical species have human toxicity endpoints and some have
Maximum Contaminant Levels (MCLs) established under the Safe Drinking Water Act. Data sources
that provide information on levels of bromide, bromate, iodide, chlorate and perchlorate in oil/gas and
hydraulic fracturing-related wastewaters associated with different geologic formations where HF is
occurring are provided in section d2 below.
In Chapter 7, the agency should also increase the emphasis on and better explain the use of
impoundments for hydraulic fracturing flowback and production waters. The chapter states that, "The
causes of these spills were human error (38%), equipment failure (17%), failures of container integrity
(13%), miscellaneous causes (e.g., well communication, well blowout), and unknown causes. Most of the
volume spilled (74%), however, came from spills caused by a failure of container integrity. " While an
impoundment example is given on pages 7-41 to 7-42 and impoundments are mentioned in the draft
Assessment Report, impoundments are not emphasized sufficiently, nor are they clearly distinguished
from containment structures used to contain leaks and spills from storage containers or from hydraulic
fracturing operations. The EPA should describe best practices regarding the use of impoundments and
how are they constructed, monitored, and regulated. Since the EPA notes that container leakage (i.e.,
leakage from pits, impoundments or tanks) is the single biggest source of leakage on an event basis, the
nature and use of hydraulic fracturing impoundments and other containment structures are particularly
important to fully describe in the final Assessment Report. It is especially important for EPA to clearly
distinguish leaks and spills that escape containment from those that do not, and to distinguish leaks from
produced water storage impoundments from leaks and spills from chemical storage containers and other
containers that are typically far smaller in size than produced water storage impoundments.
The EPA should obtain and evaluate, as a longer-term future activity, available data concerning
impoundment leakage and location, and describe whether leaks from impoundments occur more
frequently if such impoundments are placed in different geographic locations such as in floodplains or
along ridgelines. The SAB notes that in some parts of the country (e.g., Pennsylvania), impoundments
are being used less frequently than in previous years, and the EPA should summarize any such changes
in best management practice and the reasons for these changes. Furthermore, page 7-44 of the draft
Assessment Report points to USGS studies, but should discuss and cite these studies in Section 7.7.2.3
of the final Assessment Report. In addition, the EPA should discuss the cause of the structural lack of
integrity responsible for leaks from impoundments, and whether leaks from impoundments are induced
by operational conditions, poor manufacturing of materials (e.g., linings or tanks), corrosion caused by
the flowback or produced water chemistry, or by seismic activity. The EPA should also concisely
describe which states have laws or regulations requiring lined pits and bermed areas to manage potential
spills, leaks and runoff from hydraulic fracturing operations, and include a list of best practices currently
in use in industry (such as the elimination of unlined pits, and use of tanks stored over lined berm-
surrounded catchment areas). This summary of best management practices and regulatory changes need
not be an exhaustive analysis of such practices and changes. The EPA may develop these summaries as
longer-term future activity.
In addition, the term "containment" is not adequately described in the draft Assessment Report. The
EPA should describe it adequately in the final Assessment Report and also more specifically discuss
whether spills are being contained or escaping containment and whether the containment structures for
hydraulic fracturing materials and fluids are being adequately designed, operated, maintained, and
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eventually decommissioned. In addition, the terms "impoundment," "container," and "containment" are
not defined in the Glossary (Appendix J) and the EPA should consider including such definitions in this
appendix of the final Assessment Report.
The final Assessment Report should increase the emphasis on, and better explain the presence of, natural
brines in the subsurface as encountered during or in the vicinity of hydraulic fracturing operations. Brine
salts have been identified in an incident with respect to drinking water (Boyer et al. 2012), but available
literature does not describe where these salts came from. The brines may have originated as ancient
brines (millions of years old) that originally were contained in pores of near-surface rocks that have
since been deeply buried, rather than from hydraulic fracturing wastewater spills or leaks; the chapter
should address this type of potential source. The EPA should also explain in the chapter that there can be
natural pathways of brines to the surface, that these natural pathways are not necessarily related to shale
gas development, and that brine salts can contaminate aquifers and surface waters naturally. The SAB
notes that this complicates the EPA's interpretation of spilled liquids and leaks of flowback and
production waters because the background conditions can be marked by the same salts that influence the
composition of flowback and produced waters. The SAB notes that the presence of natural brines from
depth that move to the surface or to shallow groundwater is especially important since there is
significant public concern regarding the transport of hydraulic fracturing fluid from the deep subsurface
of unconventional gas reservoirs to groundwater or surface water. While the potential and rate of such
transport may be very low in the context of shale gas development, the SAB recommends that the EPA
discuss this pathway and mechanism of brine movement in this chapter in the context of natural brines,
salt springs, and salt licks. The EPA should also discuss whether the presence of shallow brines implies
transport upward from depth or not, and if yes, what implications, if any, this transport may have for
injected fluids during hydraulic fracturing. A publication authored by Gupta and Bair (1997) shows
simulated flow directions of brines in the Cambrian Mt. Simon Sandstone and other younger Paleozoic
rocks around the Appalachian, Michigan, Illinois basins in the midwestern United States. The three-
dimensional, variable fluid density flow model was calibrated using measured values of bottom-hole
pressures in oil/gas wells and Class I injection wells in the region. Both the model results and the
measured bottom-hole pressures indicate that the flow rates of the brines are exceptionally low and flow
directions in the deep subsurface can be upward, downward or lateral, much like the flow systems
described by Toth (1963 1988). Thus, at least in the this region of the country, movement of brines,
albeit very slow, is not always upward as assumed in many modeling studies examining the flow of
injection fluids beyond the target zone for hydraulic fracturing.
The EPA should include additional discussion within Chapter 7 on the importance of background and
pre-existing chemistry of surface and groundwater in developing a better understanding of whether
impacts from drilling and completion activities can be identified. In this discussion it would be helpful
for the EPA to describe how to ascertain background condition of a waterway or aquifer, define what
"background" is, and describe situations where background conditions of waters may be an important
factor in considering potential impacts. The chapter's discussion on pre-existing conditions in
groundwater and surface waters is only provided in one paragraph on page 7-35. The EPA's discussion
on background conditions should include the importance of gathering pre-existing methane
concentrations or other constituents in numerous potable wells from non-target geologic zones, to help
in assessing whether any constituent detected in groundwater near oil and gas operations is originating
from those operations.
In addition, the EPA should include MCLs if available for constituents listed in Table 7-4. A major
public concern is the appearance of contaminated or degraded drinking water in wells in areas where
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hydraulic fracturing occurs. Since naturally occurring contaminants and degraded drinking water in
wells can occur from issues not related to hydraulic fracturing, the EPA should also discuss the
importance of background and pre-existing chemistry of surface and groundwater in developing a better
understanding of whether impacts from drilling and completion activities can be identified. The
scientific complexity of baseline sampling and data interpretation should be clearly and concisely
described. Although baseline sampling is simple in concept, it can be very difficult to obtain meaningful
results in practice. Concentrations of naturally occurring contaminants, including methane, aromatic
hydrocarbons, radionuclides, and disinfection by-product precursors, can vary significantly, both
temporally and spatially, especially in surface water and in groundwater drawn from shallow and/or
alluvial wells. Water quality can be significantly influenced by hydrological events (rainfall, flooding,
drought), by water acquisition for purposes other than hydraulic fracturing, and by spills or discharges or
constituents not associated with hydraulic fracturing. Obtaining representative samples, characterizing
natural variations in water quality, properly collecting (and preserving and storing) samples for the
analytes of interest, accurately determining the concentrations of the analytes of interest, and correctly
interpreting the data can be challenging tasks. Interpretation of water chemistry data from private wells,
whether from baseline sampling or subsequent sampling, and attribution of possible causes of changes in
water chemistry is not straightforward and can be complex. The analysis of water chemistry data from
private wells requires the water chemistry data to be integrated with water-level data and details about
the construction and maintenance history of each well. Interpretation and attribution can be confounded
by several factors including:
• Changes in groundwater flow directions, both vertical and lateral;
• The age of the well, type of casing, presence or absence of a well screen and water-treatment
equipment, aquifer materials, competency of cement and grout seals;
• The maintenance history of the well — routine disinfection of the wellbore, presence of mineral
deposits and bacterial slimes in the well and the screen, and corrosion of the casing and screen;
and
• The location and depth of the well relative to septic tanks; yard, household, and automotive
chemicals; and livestock.
Chemical analyses and water levels also need to be measured periodically so that temporal and spatial
trends can be assessed. Relevant information can be found in various sources, including Minnesota
Department of Health (2014), and U.S. Geological Survey (1994).
As described in the EPA's research Study Plan (U.S. EPA 2011), the EPA had planned to evaluate the
potential use of tracer constituents that could be used in hydraulic fracturing injectate to fingerprint fluid
provenance. While the draft Assessment Report includes little on this topic, the EPA should provide
some discussion of it and clarify that there are two types of tracers in use: minerals naturally present in
the geologic formation and ions present in brines that can be measured in flowback or produced waters
as a putative "fingerprint" of the formational waters, and elements or constituents injected into the
fracturing fluids intentionally to allow analysis of well completion or cement squeeze processes. The
EPA discusses minerals naturally present in the formation or brine in the chapter, but the EPA does not
sufficiently discuss elements or constituents injected into the fracturing fluids intentionally in the
chapter. The EPA should explicitly describe in the chapter whether it recommends the use of fingerprint
constituents in injected fluids, and what additional information is needed to evaluate whether to use
these constituents for this purpose. Some authors have argued that organic compounds have moved
kilometers from drilled wells (Llewellyn et al. 2015), and the EPA should assess whether the use of
fingerprint constituents could elucidate such mobility, if the fingerprint constituents had been injected
originally into the well.
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Within the EPA's Study Plan (U.S. EPA 2011), the EPA described several activities where it planned to
inject tracer or fingerprint analyses:
i) page 39: Prospective case studies. The prospective case studies will give the EPA a better
understanding of the processes and tools used to determine the location of local geologic and/or
man-made features prior to hydraulic fracturing. The EPA will also evaluate the impacts of local
geologic and/or man-made features on the fate and transport of chemical contaminants to
drinking water resources by measuring water quality before, during, and after injection. The
EPA is exploring the possibility of using chemical tracers to track the fate and transport of
injectedfracturing fluids. The tracers may be used to determine iffracturing fluid migrates from
the targetedformation to an aquifer via existing natural or man-made pathways.
ii) page 113: As part of these efforts, the EPA and DOE are working together on a prospective
case study located in the Marcellus Shale region that leverages DOE's capabilities in field-
based monitoring of environmental signals. DOE is conducting soil gas surveys, hydraulic
fracturing tracer studies, and electromagnetic induction surveys to identify possible migration of
natural gas, completion fluids, or production fluids.
Although the prospective case studies were not initiated, the EPA should nonetheless explicitly assess
and describe the potential for development of tracer metals or constituents that could be injected along
with hydraulic fracturing fluids, drilling fluids, or cement squeezes that could help in forensic analysis
of incidents related to those injections. The DOE's National Energy Technology Laboratory evaluated
fracture growth and fluid migration from HFWC activities and the results of that investigation should be
considered by the EPA (US DOE 2014).
The SAB recommends that the EPA outline a plan for analyzing organic compounds in HF flowback
and produced waters, in collaboration with state agencies. The EPA should also assess whether the
costs/benefits for conducting such an intense effort, and whether such an effort would advance the
assessment of potential impacts on drinking water. In addition, the EPA should evaluate as a longer-term
future activity the potential for using non-targeted chemical analysis to identify currently unmonitored
HF constituents. In Chapter 7, the agency should clarify the importance of data gaps associated with
analyzing organics in public drinking water supplies, describe the difficulties in conducting such
analysis, and note that such analysis may not be the most effective way to identify hydraulic fracturing-
related spills. Furthermore, the discussion in Section 7.4.5 on analysis of constituents in water should
cite new techniques of analysis that measure broad categories of compounds rather than individual
compounds (Llewellyn et al. 2015). Llewellyn et al. argue that a better approach for determining
contaminants may be to look for suites of organic compounds that provide fingerprints as patterns, rather
than to search for individual compounds which may be too difficult. Llewellyn et al. could also be cited
on p. 7-45. The SAB also finds that many constituents in produced waters are often categorized as
BTEX constituents, and that these constituents are frequently found in hydraulic fracturing wastewaters
because the constituents come out of the shales themselves. The chapter should note that while
petroleum (oil/condensate) contains many hundreds of individual constituents that could be included in
the dissolved phase as trace components, these constituents are generally classified as BTEX and total
petroleum hydrocarbons.
Chapter 7 of the draft Assessment Report does not adequately discuss or assess microbial processes
associated with hydraulic fracturing operations and the related potential impacts to drinking water
resources. The fate and transport of hydraulic fracturing constituents are often very dependent on
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microbial reactions, especially for organic constituents. The SAB recommends that the EPA further
describe microbial processes that affect the transformation of chemicals recovered in flow back and
produced water, and the transformation of chemicals that may impact ground and surface waters, within
the discussion on adsorption, absorption, and precipitation on line 26 of page 7-42 of the draft
Assessment Report. A reference on this topic is Akob (2015). Because most HF fluids contain a biocide,
the influence of these on microbial processes should be considered. Some discussion should be added to
the final Assessment Report; a full investigation of microbial processes would be a longer-term future
activity.
The EPA used the EPI Suite of models to estimate various properties of hydraulic fracturing
constituents. EPI Suite is a group of models that employ some parameters that are uncertain and require
detailed sensitivity analysis to assess whether the model provides meaningful results. The EPA should
also include information on chemical mechanisms or factors that EPI Suite does not consider when
estimating various properties of hydraulic fracturing constituents. While the draft Assessment Report
notes on page 7-43 that high salinity is not adequately incorporated into those EPI Suite estimations, the
EPA should revise the chapter and describe whether and how other potentially important factors such as
microbiological reactions are assessed. The EPA's approach to determine mobility of certain hydraulic
fracturing constituents is based on very limited data, and the EPA should revise the chapter and describe
how subsurface biogeochemical reactions may change the properties of hydraulic fracturing constituents
and make them more or less mobile than their original state. Given the large uncertainties associated
with unknown hydraulic fracturing constituents and unknown subsurface reactions that may change the
mobility of hydraulic fracturing constituents, the EPA should further describe the usefulness of using
EPI Suite analysis when assessing potential impacts of hydraulic fracturing constituents on drinking
water resources. In addition to using EPI Suite, the EPA should discuss the presence or absence of
alternative models and the availability of physical/chemical data compilations. Additional databases that
the EPA should consider using are described in the response to Charge Question 7 within the body of the
SAB report.
Also, the EPA should include additional analysis and discussion on how recycled hydraulic fracturing
produced water that is reused onsite at hydraulic fracturing facilities without treatment and how this
practice might affect the severity or frequency of potential contamination of surrounding drinking water
resources. This discussion could address whether or not certain constituents in the water might build up
over time, increasing the potential for adverse impacts in the event of a leak or spill, and whether
additional storage and handling of the water on site is likely to increase the frequency of leaks and spills.
Several available references describe the reuse of flowback and produced water that the EPA should
consider when developing the final Assessment Report (e.g., Balasubramanian et al. 2015; Barnes et al.
2015; Burgos and Lebas 2015; Farrell et al. 2015; Hussain et al. 2014; McMahon et al. 2015; and Seth et
al. 2013).
The EPA should review the results of a three-year study by scientists at the University of Cincinnati who
examined potential impacts of shale gas development in the vicinity of residential wells. They found no
effects from nearby gas drilling or hydraulic fracturing in a network of 23 residential wells that were
sampled 3 to 4 times a year over a 3-year period for methane concentration and its source (biogenic or
thermogenic). The investigation was designed specifically to sample methane prior to, during, and after
natural gas drilling, hydraulic fracturing, and gas extraction. Methane measured in the wells was found
to be derived from shallow underground coal beds and not from natural gas in the Utica Shale, which
occurs at a much greater depth (Botner et al. 2014). The study covered five counties at the epicenter of
the Utica Shale gas boom in eastern Ohio and was sponsored by the National Science Foundation, two
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non-profit philanthropic organizations, and private citizens, with no funding provided by the oil and gas
industry (Botner et al. 2014).
d2. Are there relevant literature or data sources that should be added in this section of the report?
(1) Data sources that provide information on chemicals used for HF tracers and HF industry use of
tracers are provided below.
• Drylie, S., J. Pechiney, R. Villasenor, and R. Woodroof. 2015. Determining the number of
contributing fractures in shale gas wells with production analysis and proppant tracer
diagnostics. Society of Petroleum Engineers. 2015, March 1. doi: 10.2118/173620-MS.
• Elahi, S.H., and , B. Jafarpour. 2015. Characterization of fracture length and conductivity from
tracer test and production data with ensemble kalman filter. Society of Petroleum Engineers.
2015, August 4. doi: 10.2118/178707-MS.
• Goswick, R.A., and , J.L. LaRue. 2014a. Utilizing oil soluble tracers to understand stimulation
efficiency along the lateral. Society of Petroleum Engineers. 2014, January 1.
• Goswick, R.A., and , J.L. LaRue. 2014b. Utilizing Oil Soluble Tracers to Understand Stimulation
Efficiency Along the Lateral. Society of Petroleum Engineers. 2014, October 27.
doi: 10.2118/170929-MS.
• Han, X., R. Duenckel, H. Smith, and H. D. Smith. 2014. An Environmentally Friendly Method to
Evaluate Gravel and Frac Packed Intervals Using a New Non-Radioactive Tracer Technology.
Offshore Technology Conference. 2014, May 5. doi: 10.4043/25166-MS.
• Leong, Y., J.E. de Iongh, S. Bahring, A. K. Tuxen, and , T.B. Nielsen. (2015, September 28).
Estimation of fracture volume between well pairs using deuterium tracer. Society of Petroleum
Engineers. doi: 10.2118/174832-MS.
• Roney, D., D.J. Quirk, A. Ziarani, and L.H. Burke. 2014. Integration of microseismic data, tracer
information, and fracture modeling into the development of fractured horizontal wells in the
Slave Point Formation. Society of Petroleum Engineers. 2014, September 30.
doi: 10.2118/171605-MS
• Salman, A., B. Kurtoglu, and H. Kazemi. 2014. Analysis of chemical tracer flowback in
unconventional reservoirs. Society of Petroleum Engineers. 2014, September 30.
doi: 10.2118/171656-MS.
• Scott, M.P., L.J. Raymond Jr., A. Datey, C. Vandenborn, and R.A. Woodroof Jr. 2010.
Evaluating hydraulic fracture geometry from sonic anisotropy and radioactive tracer logs. Society
of Petroleum Engineers Asia Pacific Oil & Gas Conference and Exhibition. Brisbane,
Queensland, Australia, October 18-20, 2010. SPE document #SPE-133059-MS. DOI:
http://dx.doi.org/10.2118/133059-MS
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• Srinivasan, K., J. Krishnamurthy, R. Williams, P. Dharwadkar, T. Izykowski, and W.R. Moore.
2016. Eight-plus years of hydraulic fracturing in the Williston Basin: what have we learned?
Society of Petroleum Engineers. 2016, February 1. doi:10.2118/179156-MS.
(2) Data sources that provide information on well fracture time are provided below.
• Fyten, G.C., R.S. Taylor, and D. Price. 2015. Viking stimulation: case history. Society of
Petroleum Engineers. 2015, October 20. doi: 10.2118/175955-MS.
• Govorushkina, A., C. Henderson, L. Castro, R. Allen, and E. Nasir. 2015. Interventionless
unconventional multistage hybrid completion: fracturing longer laterals in cemented
applications. Society of Petroleum Engineers. 2015, November 9. doi: 10.2118/176838-MS.
• Krenger, J. T., J. Fraser, A.J. Gibson, A. Whitsett, J. Melcher, and S. Persac. 2015. Refracturing
design for underperforming unconventional horizontal reservoirs. Society of Petroleum
Engineers. 2015, October 13. doi: 10.2118/177306-MS.
• Nejad, A.M., S. Sheludko, R.F. Shelley, T. Hodgson, and P.R. Mcfall. 2015. A case history:
evaluating well completions in eagle ford shale using a data-driven approach. Society of
Petroleum Engineers. 2015, February 3. doi: 10.2118/173336-MS
• Qiu, F., M.M. Porcu, J. Xu, R. Malpani, P. Pankaj, and T.L. Pope. 2015. Simulation study of
zipper fracturing using an unconventional fracture model. Society of Petroleum Engineers. 2015,
October 20. doi: 10.2118/175980-MS.
• Reddy, L., A. Jenkins, and E. Fathi. 2015. Dynamic assessment of induced stresses and in-situ
stress reorientation during multi-stage hydraulic fracturing in unconventional reservoirs. Society
of Petroleum Engineers. 2015, October 13. doi: 10.2118/177301-MS.
• Temizel, C., S. Purwar, A. Abdullayev, K. Urrutia, and A. Tiwari. 2015. Efficient use of data
analytics in optimization of hydraulic fracturing in unconventional reservoirs. Society of
Petroleum Engineers. 2015, November 9. doi: 10.2118/177549-M.
• Yousefzadeh, A., Q. Li, and R. Aguilera. 2015. Microseismic 101: monitoring and evaluating
hydraulic fracturing to improve the efficiency of oil and gas recovery from unconventional
reservoirs. Society of Petroleum Engineers. 2015, November 18. doi: 10.2118/177277-M.
(3) Data sources that provide information on monitoring of well flowback are provided below.
• Rane, J.P., and L. Xu. 2015. New dynamic-surface-tension analysis yields improved residual
surfactant measurements in flowback and produced waters. Society of Petroleum Engineers.
2015, August 1. doi: 10.2118/172190-PA.
• Salman, A., B. Kurtoglu, and H. Kazemi. 2014. Analysis of chemical tracer flowback in
unconventional reservoirs. Society of Petroleum Engineers. 2014, September 30.
doi:10.2118/171656-MS.
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• Vazquez, O., R. Mehta, E. Mackay, S. Linares-Samaniego, M. Jordan, and J. Fidoe. 2014. Post-
frac flowback water chemistry matching in a shale development. Society of Petroleum Engineers.
2014, May 14. doi: 10.2118/169799-MS.
• Williams-Kovacs, J.D., C.R. Clarkson, and B. Zanganeh. 2015. Case studies in quantitative
flowback analysis. Society of Petroleum Engineers. 2015, October 20. doi: 10.2118/175983-MS.
• Zhou, Q., R. Dilmore, A. Kleit, and J.Y. Wang. 2016. Evaluating fracture-fluid flowback in
Marcellus using data-mining technologies. Society of Petroleum Engineers. 2016, February 1.
doi: 10.2118/173364-PA.
• Zolfaghari, A., H. Dehghanpour, E. Ghanbari, and D. Bearinger. 2015. Fracture characterization
using flowback salt-concentration transient. Society of Petroleum Engineers. 2015, June 1.
doi: 10.2118/168598-PA.
• Zolfaghari, A., Y. Tang, J. Holyk, M. Binazadeh, H. Dehghanpour, and D. Bearinger. 2015.
Chemical analysis of flowback water and downhole gas shale samples. Society of Petroleum
Engineers. 2015, October 20. doi: 10.2118/175925-MS.
(4) Data sources that provide information on levels of bromine, bromate. iodide, chlorate and
perchlorate in oil/gas and HF wastewaters associated with different geologic formations where HF is
occurring are provided below.
• Akob, D.M., M., I.M. Cozzarelli, D.S. Dunlap, E.L. Rowan, and M.M. Lorah. 2015. Organic and
inorganic composition and microbiology of produced waters from Pennsylvania shale gas wells.
Applied Geochemistry 60 (116-125). September 2015. doi:10.1016/j.apgeochem.2015.04.011.
• Blauch, M.E. 2010. Developing effective and environmentally suitable fracturing fluids using
hydraulic fracturing flowback waters. Society of Petroleum Engineers. 2010, January 1.
doi:10.2118/131784-MS.
• Chen, R., S. Sharma, T. Bank, D. Soeder, and H. Eastman. 2015. Comparison of isotopic and
geochemical characteristics of sediments from a gas- and liquids-prone wells in Marcellus shale
from Appalachian Basin, West Virginia. Applied Geochemistry 60 (59-71). September 2015.
doi:10.1016/j.apgeochem.2015.01.001.
• Down, A., K. Schreglmann, D.L. Plata, M. Eisner, N.R. Warner, A. Vengosh, K. Moore, D.
Coleman, and R.B. Jackson. 2015. Pre-drilling background groundwater quality in the Deep
River Triassic Basin of central North Carolina, USA. Applied Geochemistry 60 (3-13).
S eptemb er 2015. doi: 10.1016/j. apgeochem. 2015.01.018.
• Houston, N.A., M.E. Blauch, D.R. Weaver, D. Miller, and O'Hara, D. 2009. Fracture-stimulation
in the Marcellus shale-lessons learned in fluid selection and execution. Society of Petroleum
Engineers. 2009, January 1. doi:10.2118/125987-MS.
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Johnson, J.D., and J.R. Graney. 2015. Fingerprinting Marcellus shale waste products from Pb
isotope and trace metal perspectives. 2015. Applied Geochemistry 60 (104-115). September
2015. doi:10.1016/j.apgeochem.2015.04.021.
Johnson, J.D., J.R. Graney, R.C. Capo, and B.W. Stewart. Identification and quantification of
regional brine and road salt sources in watersheds along the New York/Pennsylvania border,
USA. Applied Geochemistry 60 (37-50). September 2015.
doi:10.1016/j.apgeochem.2014.08.002.
King, G.E. 2012. Hydraulic fracturing 101: what every representative, environmentalist,
regulator, reporter, investor, university researcher, neighbor and engineer should know about
estimating frac risk and improving frac performance in unconventional gas and oil wells. Society
of Petroleum Engineers. 2012, January 1. doi: 10.2118/152596-MS
Lu, Z., S.T. Hummel, L.K. Lautz, G.D. Hoke, X. Zhou, J. Leone, and D.I. Siegel. 2015. Iodine as
a sensitive tracer for detecting influence of organic-rich shale in shallow groundwater. Applied
Geochemistry 60 (29-36). September 2015 doi:10.1016/j.apgeochem.2014.10.019
Macpherson, G.L. Lithium in fluids from Paleozoic-aged reservoirs, 2015. Appalachian Plateau
region, USA. Applied Geochemistry 60 (72-77). September 2015.
doi:10.1016/j.apgeochem.2015.04.013.
Phan, T.T.; R.C. Capo, B.W. Stewart, J.R. Graney, J.D. Johnson, S. Sharma, and J. Toro. 2015.
Trace metal distribution and mobility in drill cuttings and produced waters from Marcellus Shale
gas extraction: Uranium, arsenic, barium. Applied Geochemistry 60 (89-103). September 2015.
doi:10.1016/j.apgeochem.2015.01.013
Rane, J.P., and L. Xu. 2014. Monitoring residual surfactant in the flowback and produced water:
a way forward to improve well productivity. Society of Petroleum Engineers. 2014, April 21.
doi: 10.2118/172190-MS
Rhodes, A.L., and N.J. Horton. 2015. Establishing baseline water quality for household wells
within the Marcellus Shale gas region, Susquehanna County, Pennsylvania, U.S.A. Applied
Geochemistry 60 (14-28). September 2015. doi:10.1016/j.apgeochem.2015.03.004.
Rimassa, S.M., P.R. Howard, B. MacKay, K.A. Blow, andN. Coffman. 2011. Case study:
evaluation of an oxidative biocide during and after a hydraulic fracturing job in the Marcellus
Shale. Society of Petroleum Engineers. 2011, January 1. doi:10.2118/141211-MS.
Schachter, H.E. 2014. Detailed description of petro-cycle solutions innovative process for the
remediation, recycle and reuse of "frac water and flow back water" for the oil and gas industry
across the USA and Canada. Society of Petroleum Engineers. 2014, August 28.
doi: 10.15 5 3 0/urtec-2014-1921626.
Sharma, S., L. Bowman, K. Schroeder, and R. Hammack. 2015. Assessing changes in gas
migration pathways at a hydraulic fracturing site: Example from Greene County, Pennsylvania,
USA. Applied Geochemistry 60 (51-58). September 2015.
doi:10.1016/j.apgeochem.2014.07.018.
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• Stewart, B.W., R.C. Capo, and C.S. Kirby. 2015. Geochemistry of unconventional shale gas
from formation to extraction: Petrogenesis, hydraulic fracturing, and environmental impacts.
Applied Geochemistry 60 (1-126). September 2015. doi:10.1016/j.apgeochem.2015.06.012.
• Stewart, B.W., E.C. Chapman, R.C. Capo, J.D. Johnson, J.R. Graney, C.S. Kirby, and K.T.
Schroeder. 2015. Origin of brines, salts and carbonate from shales of the Marcellus Formation:
Evidence from geochemical and Sr isotope study of sequentially extracted fluids. Applied
Geochemistry 60 (78-88). September 2015. doi:10.1016/j.apgeochem.2015.01.004.
• Tischler, A., T.R. Woodworth, S.D. Burton, and R.D. Richards. 2009. Controlling bacteria in
recycled production water for completion and workover operations. Society of Petroleum
Engineers. 2009, January 1. doi:10.2118/123450-MS.
(5) Data sources that provide information on best management practices for HF flowback and produced
water, and regulatory requirements for secondary containment are provided below:
• Maloney, K.O. and D.A. Yoxtheimer. 2012. Production and disposal of waste materials from gas
and oil extraction from the Marcellus shale play in Pennsylvania. Environmental Practice 14,
278-287, doi:210.10170S146604661200035X.
• Rahm, B.G., J.T. Bates, L.R. Bertoia, A.E. Galford, D.A. Yoxtheimer, and S.J. Riha. 2013.
Wastewater management and Marcellus Shale gas development: Trends, drivers, and planning
implications. Journal of Environmental Management 120, 105-113, doi:
101.1016/j.jenvman.2013.1002.1029.
(6) Data sources that provide information on long-distance travel of HF constituents are provided below:
• Brantley, S.L., D. Yoxtheimer, S. Arjmand, P. Grieve, R. Vidic, J. Pollak, G.T. Llewellyn, J.
Abad, and C. Simon. 2014. Water resource impacts during unconventional shale gas
development: The Pennsylvania experience. International Journal of Coal Geology 126, 140-
156, dx.doi.org/110.1016/j.coal.2013.1012.1017.
• Llewellyn, G., F.L. Dorman, J.L. Westland, D. Yoxtheimer, P. Grieve, T. Sowers, E. Humston-
Flumer, and S.L. Brantley. 2015. A drinking water contamination incident attributed to
Marcellus Shale gas development. Proceedings of the National Academy of Sciences 112, 6325-
6330.
(7) Data sources that provide information on reuse of flowback and produces water are provided below:
• Balasubramanian, R., R. Ryther, R. De Paula, B. Epps, V. Keasler, J. Li, and R. Staub. 2015.
Development of very low peroxide containing peracid formulation as superior treatment option
for water reuse applications, Society of Petroleum Engineers (SPE), SPE International
Symposium on Oilfield Chemistry. The Woodlands, Texas, USA 13-15 April 2015, SPE-173780-
MS.
• Barnes, C.M., R. Marshall, J. Mason, D. Skodack, G. DeFosse, D.G. Smith, S. Foreman, T.
Hanna, and M. Cecchini. 2015. The new reality of hydraulic fracturing: treating produced water
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is cheaper than using fresh. Society of Petroleum Engineers (SPE), SPE International Symposium
on Oilfield Chemistry. Houston, Texas, USA 28-30 September 2015, SPE-174956-MS.
• Burgos, M. and G. Lebas. 2015. Beneficial reuse of production water for irrigation. International
Petroleum Technology Conference (IPTC). Doha, Qatar 6-9 December 2015. IPTC-18389-MS.
• Farrell, J.W., T. Baudendlstel, and M. Kidder. 2015. Water-flexible fracturing systems.
Unconventional Resources Technology Conference. San Antonio, Texas, USA, 20-22 July 2015.
SPE-178699-MS/URTeC: 2173887.
• Hussain, A., J. Minier-Matar, A. Janson, and S. Adham. 2014. Advanced technologies for
produced water treatment and reuse. Internation Petroleum Technology Conference (IPTC).
Doha, Qatar 20-22 January 2014. IPTC 17394.
• McMahon, B., B. MacKay, and A. Mirakyan. 2015. First 100% reuse of Bakken produced water
in hybrid treatments using inexpensive polysaccharide gelling agents. Society of Petroleum
Engineers (SPE), SPE International Symposium on Oilfield Chemistry. The Woodlands, Texas,
USA 13-15 April 2015, SPE-173783-MS.
• Seth, K., S. Shipman, M. McCutchan, and D. McConnell. 2013. Maximizing flowback reuse and
reducing freshwater demand: Case studies from the challenging Marcellus shale. Society of
Petroleum Engineers (SPE), SPE Eastern Regional Meeting. Pittsburgh, Pennsylvania, USA 20-
22 August 2013. SPE 165693.
(8) The SAB recommends that the EPA consider the following additional literature sources within this
chapter of the final Assessment Report:
• Akob, D.M.; I.M. Cozzarelli, D.S. Dunlap, E.L. Rowan, and M.M. Lorah. Organic and inorganic
composition and microbiology of produced waters from Pennsylvania shale gas wells. 2015.
Applied Geochemistry 60 (116-125). September 2015. doi:10.1016/j.apgeochem.2015.04.011.
• Amy, G., M. Siddiqui, W. Zhai, J. DeBroux, and W. Odem. 1994. American Water Works
Association Research Foundation (AwwaRF) Final Report - Survey on bromide in drinking
water and impacts on DBP formation. American Water Works Association Research Foundation.
• Bachu, S. and R.L. Valencia. 2014. Well Integrity: Challenges and Risk Mitigation Measures.
The Bridge 44(2): 28-34.
• Bair, E.S., and R.K. Digel. 1990. Subsurface transport of inorganic and organic solutes from
experimental spreading of oil-field brine. Ground Water Monitoring and Remediation, vol. 10,
no. 3, p. 94 - 105.
• Balashov, V.N., T. Engelder, X. Gu, M.S. Fantle, and S.L. Brantley. 2015. A model describing
flowback chemistry changes with time after Marcellus Shale hydraulic fracturing. American
Association of Petroleum Geologists Bulletin 99(1), 143-154. January 2015. doi:
110.1306/06041413119.
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Botner, Elizabeth C., D. Nash, and C. Paul. Monitoring methane levels and sources in
groundwater before and after the onset of fracking in the Utica Shale of Ohio, USA. 2014. 2014
GSA Annual Meeting in Vancouver, British Columbia (19-22 October 2014)
Boyer, E.W., B.R. Swistock, J. Clark, M. Madden, and D.E. Rizzo. 2012. The impact of
Marcellus Gas Drilling on Rural Drinking Water Supplies. The Center for Rural Pennsylvania,
Pennsylvania General Assembly,
http://www.rural.palegislature.us/documents/reports/Marcellus and drinking water 2012.pdf
accessed October 2014, Harrisburg, PA.
Brantley, S.L., D. Yoxtheimer, S. Arjmand, P. Grieve, R. Vidic, J. Pollak, G.T. Llewellyn, J.
Abad, and C. Simon. 2014. Water resource impacts during unconventional shale gas
development: The Pennsylvania experience. International Journal of Coal Geology 126, p. 140-
156. June 1, 2014. dx.doi.org/110.1016/j.coal.2013.1012.1017
Drollette, B.D., K. Hoelzer, N R. Warner, T.H. Darrah, O. Karatum, M P. O'Connor, R.K.
Nelson, L.A. Fernandez, C.M. Reddy, A. Vengosh, R.B. Jackson, M. Eisner, and D.L. Plata.
2015. Elevated levels of diesel range organic compounds in groundwater near Marcellus gas
operations are derived from surface activities. Proceedings of the National Academy of Sciences
112(43), p. 13184-13189. October 27, 2015. doi/10.1073/pnas,1511474112.
Ferrar, K.J., D.R. Michanowicz, C.L. Christen, N. Mulcahy, S.L. Malone, and R.K. Sharma.
2013. Assessment of effluent contaminants from three facilities discharging Marcellus shale
wastewater to surface waters in Pennsylvania. Environ. Sci. and Tech. 47(7), p.3472-81. April 2,
2013. dx.doi.org/10.1021/es30141 lq.
Gupta, N., and E.S. Bair, 1997. Variable-density flow in the midcontinent basins and arches
region: Water Resources Research, vol. 33, no. 8, p. 1785-1802.
Jackson, R.B., E.R. Lowry, A. Pickle, M. Knag, D. DiGiulio, and K. Zhao. 2015. The depths of
hydraulic fracturing and accompanying water use across the United States. Environ. Sci.
Technol. 49(15), p. 8969-8976. doi: 10.1021/acs.est.5b01228.
Llewellyn, G., F.L. Dorman, J.L. Westland, D. Yoxtheimer, P. Grieve, T. Sowers, E. Humston-
Flumer, and S.L. Brantley. 2015. Evaluating a groundwater supply contamination incident
attributed to Marcellus Shale gas development. Proceedings of the National Academy of Sciences
112(20), 6325-6330. May 19, 2015. doi: 10.1073/pnas. 1420279112.
Leenheer, J.A., T.I. Noyes, and H.A. Stuber. 1982. Determination of polar organic solutes in oil-
shale retort water. Environ. Sci. and Tech. 16(10), p. 714-723. October 1982. doi:
10.1021/es00104a015.
Leri, A.C., and S.C.B. Myneni. 2012. Natural organobromine in terrestrial ecosystems.
Geochimica Cosmochimica Acta 77, p. 1-10. January 15, 2012.
doi:10.1016/j.gca.2011.1011.1012.National Research Council (2013) Alternatives for Managing
the Nation's Complex Contaminated Groundwater Sites. National Academies Press, Washington
DC.
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Minnesota Department of Health. 2014. Well owner's handbook - a consumer's guide to water
wells in Minnesota. Well Management Section, Environmental Health Division, Minnesota
Department of Health. Available at:
http://www.health.state.mn.us/divs/eh/wells/construction/handbook.pdf.
Sloto, R.A. 2013. Baseline groundwater quality from 20 domestic wells in Sullivan County,
Pennsylvania, 2012. U.S. Geological Survey Scientific Investigations Report 2013-5085.
http://pubs.usgs.gov/sir/2013/5Q85/.
States, S., G. Cyprych, M. Stoner, F. Wydra, J. Kuchta, J. Monnell, and L. Casson. 2013.
Marcellus Shale drilling and brominated THMs in Pittsburgh, Pa., drinking water. J. American
Water Works Association 105(8), p. E432-E448. August 2013. doi:
http://dx.doi.org/10.5Q42/jawwa.2013.105.0093.
Toth, J.. 1963. A theoretical analysis of groundwater flow in small drainage basins. Journal of
Geophysical Research, vol. 68, no. 16, p. 4795-4812.
Toth, J.. 1988. Ground water and hydrocarbon migration. In Hydrogeology, Geology of North
America, vol. 0-2, ed. Back, W., Rosenshein, J.S., and Seaber, P.R., Geological Society of
America, Boulder, CO, p. 485-502.
U.S. DOE (U.S. Department of Energy). 2014. An Evaluation of Fracture Growth and Gas/Fluid
Migration as Horizontal Marcellus Shale Gas Wells are Hydraulically Fractured in Greene
County, Pennsylvania. NETL-TRS-3-2014. September 15, 2014.
https://www.netl.doe.gov/File%20Librarv/Research/onsite%20research/publications/NETL-
TRS-3-2014 Greene-Countv-Site 20140915 1 l.pdf.
USGS (U.S. Geological Survey). 1994. Ground water and the rural homeowner. Available at:
http://pubs.usgs.gov/gip/gw ruralhomeowner/
Vidic, R.D., S.L. Brantley, J.M. Vandenbossche, D. Yoxtheimer, and J.D. Abad. 2013. Impact of
Shale Gas Development on Regional Water Quality. Science 340(6134), p. 826-835. May 17,
2013. DOI: 10.1126/science. 1235009.
Wilson, J.M., and J.M. VanBriesen. 2012. Oil and gas produced water management and surface
drinking water sources in Pennsylvania. Environmental Practice 14(4), p. 288-300. December
2012. doi: 10.1017/S1466046612000427.
WY Oil and Gas Commission. 2013. Appendix K Sampling and Analysis Procedures for the
Wyoming Oil and Gas Conservation Commission Groundwater Baseline Sampling, Analysis,
and Monitoring Program. Wyoming Oil and Gas Conservation Commission.
http://wogcc.state.wv.us/downloads/WOGCC APPENDIX K 2013 Final 1223 13.pdf.
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3.6. Wastewater Treatment and Waste Disposal Stage in the HFWC
Question 6: The fifth stage in the HFWC focuses on wastewater treatment and waste disposal: the reuse,
treatment and release, or disposal of wastewater generated at the well pad. This is addressed in Chapter
8.
a. Does the assessment clearly and accurately summarize the available information concerning
hydraulic fracturing wastewater management, treatment, and disposal?
b. Are the major findings concerning wastewater treatment and disposal fully supported by the
information and data presented in the assessment? Do these major findings identify the
potential impacts to drinking water resources due to this stage of the HFWC? Are there other
major findings that have not been brought forward? Are the factors affecting the frequency
or severity of any impacts described to the extent possible andfully supported?
c. Are the uncertainties, assumptions, and limitations concerning wastewater treatment and
waste disposal fully and clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water resources
from this stage of the HFWC? Are there relevant literature or data sources that should be
added in this section of the report?
Chapter 8 presents a discussion on wastewater treatment and waste disposal, in particular the reuse,
treatment and discharge, and disposal of wastewater generated at the well pad in the HFWC. The chapter
describes volumes of hydraulic fracturing wastewater (including estimates at national, regional, state and
geologic formation levels, and estimation methods and their associated challenges), and hydraulic
fracturing-related wastewater characteristics including a discussion on what is wastewater. The chapter
presents a discussion on constituents in wastewater treatment residuals, wastewater management
practices, underground injection for disposal, CWTFs, hydraulic fracturing water reuse, evaporation,
publicly owned treatment works, and other management practices and issues. The chapter also examines
treatment processes for hydraulic fracturing wastewater, treatment of hydraulic fracturing waste
constituents, and potential impacts on drinking water resources, and discusses hydraulic fracturing
treatment issues associated with bromide and chloride, radionuclides, metal cations, volatile organic
compounds, semi-volatile organic compounds, and oil and grease. The chapter concludes with a
synthesis of major findings, discussion on factors affecting the frequency or severity of impacts, and
description of uncertainties.
3.6.1. Hydraulic Fracturing Wastewater Management, Treatment and Disposal
a. Does the assessment clearly and accurately summarize the available information concerning
hydraulic fracturing wastewater management, treatment, and disposal?
Chapter 8 in the draft Assessment Report clearly and accurately summarizes a large amount of available
information concerning the management, treatment, and disposal of hydraulic fracturing wastewater.
However, the chapter should also clearly and accurately summarize available information concerning
the regulatory framework for hydraulic fracturing-related wastewater management; the fundamental
principles of some of the treatment technologies described; the occurrence and removal of disinfection
by-product (DBP) precursors in addition to bromide; additional aspects of "waste disposal," including
cuttings, drilling muds, and treatment residuals; the locations of hydraulic fracturing-related wastewater
treatment and disposal facilities relative to downstream/downgradient public water supply (PWS)
intakes and wells; the impacts of water recycling on pollutant concentrations and their potential impacts
on drinking water quality (increased risks) should spills of recycled water occur; trends in hydraulic
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fracturing-related wastewater disposal methods, including the scientific and economic drivers of these
changes and their potential impacts on drinking water resources; and the potential impacts of seismic
activity associated with hydraulic fracturing-related wastewater disposal in deep well injection wells on
oil and gas production infrastructure (e.g., damage to wells and storage vessels, and also to pipelines
transporting water and wastewater), and on PWS infrastructure (e.g., damage to public water supply
wells).
Regulatory Framework for HF Wastewater Treatment
The regulatory framework for oversight of CWTFs and of POTWs receiving discharges of wastewater
associated with hydraulic fracturing is inadequately described. Some regulatory information is provided
in fragmentary and anecdotal fashion (e.g., in Text Box 8-1), but the pertinent regulations are not clearly
summarized, so it is not clear to the reader who is responsible for each of the various aspects of
wastewater treatment and waste disposal discussed in Chapter 8. The final Assessment Report should
specify: which, if any, local, state or federal agencies regulate CWTFs and their residuals, including
under which statutes [e.g., the Clean Water Act (CWA)/National Pollutant Discharge Elimination
System (NPDES), Resource Conservation and Recovery Act (RCRA), and state regulations]; whether
any exemptions for CWTFs exist; and whether POTWs accepting hydraulic fracturing-related
wastewater discharges associated with oil and gas production are required to adopt a sewer use
ordinance limiting such discharges (or specific components thereof) before receiving an NPDES permit,
and whether the treatment residuals from these POTWs are exempt under RCRA. In addition,
information dealing with deep well injection of hydraulic fracturing-related wastewater in Chapter 7 of
the draft Assessment Report should be moved to and consolidated in Chapter 8 of the final Assessment
Report.
Treatment Technologies and Costs
While the summary of treatment technologies in Chapter 8 is generally adequate, the chapter requires
more accurate and fundamentally sound descriptions of some technologies and their performance.
Chapter 8 does not adequately consider temporal trends for costs of hydraulic fracturing water
purification technologies over the past decade, trends in hydraulic fracturing-related wastewater disposal
methods including the scientific, regulatory and economic drivers of these changes and their potential
impacts on drinking water resources, nor potential future trajectories (e.g., if deep well injection of
hydraulic fracturing-related wastewater is being reduced because of regulatory changes driven by public
concerns about seismic activity and its associated costs.) An assessment of these trends and costs should
be included in the final Assessment Report. The EPA should consider use of the EPA's costing
information developed for wastewater treatment (U.S. EPA 1979a; 1979b; 1979c). The final Assessment
Report should use the EPA cost-curves or other comparative assessment tools to address relative capital
plus operation and maintenance costs for the major wastewater treatment technologies. The SAB
recommends that these activities be addressed in the final Assessment Report. However, to avoid undue
delay in publishing the final Assessment Report, the SAB recommends that the activities that cannot be
promptly addressed without further study should be identified in the Assessment Report as research
needs to be addressed as a longer-term future activity
Disposal Options and Costs
The agency should clearly and accurately summarize trends in oil and gas wastewater disposal in
Chapter 8. Disposal techniques have changed significantly over the past 15 years, and are likely to
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continue changing. There are inadequate scientific and economic descriptions of the drivers for these
changes. The economic costs associated with different wastewater disposal options for hydraulic
fracturing wastewater are not and should be adequately summarized. The final Assessment Report
should also discuss likely future trends in hydraulic fracturing-related wastewater disposal, and describe
and assess future uncertainties. For example, the final Assessment Report should discuss where
hydraulic fracturing wastewaters would likely end up if seismic activity leads to curtailment of deep
well injection of hydraulic fracturing wastes, and what will be done with hydraulic fracturing produced
waters that are recycled if well drilling slows and there is less demand for recycled water for hydraulic
fracturing.
As a longer-term future activity, the EPA should evaluate whether trends for deep well injection of
hydraulic fracturing-related wastewater are being reduced because of regulatory changes driven by
public concerns about seismic activity and its associated costs (as recently occurred in Oklahoma; see
Wines 2016).
The final Assessment Report should clarify what is meant by "waste disposal." The title of Chapter 8
(Wastewater Treatment and Waste Disposal) is ambiguous and the text is not clear as to whether
"waste" includes only those wastes generated during hydraulic fracturing-related wastewater treatment
or is more broadly construed to include other wastes associated with hydraulic fracturing. While the
draft Assessment Report does address treatment residuals, the SAB finds that it should further describe
the management of other hydraulic fracturing materials such as drill cuttings and drilling muds and the
potential of these materials to impact drinking water resources. The EPA should explicitly describe and
provide supporting documentation regarding the disposal routes for these wastes, and whether drilling
wastes are normally disposed in regulated landfills having low potential to leach constituents of concern
into nearby drinking water sources. The final Assessment Report should also discuss how hydraulic
fracturing spill-contaminated soils, pond sediments, and other solid media that are potentially impacted
by hydraulic fracturing constituents are managed and disposed, and whether the EPA considers these
potentially impacted media as "site reclamation" activities that the agency excluded from this report (as
noted on p. ES-4). If so, the EPA should reiterate this point in Chapter 8 for clarity. Within this
discussion, the EPA should clarify the extent to which these wastes are regulated, and options for
disposing of them in a legal manner. If the regulations include reporting requirements (e.g., as required
for other hazardous wastes under RCRA), then the EPA should consider reviewing the repositories for
such reports as a source of data for this discussion.
Organic Constituents in Wastewater
Chapter 8 describes typical wastewater characteristics for flowback and produced water with major
categories including organics, inorganics, total dissolved solids (TDS), and radionuclides. While the
description provided for TDS and inorganic characteristics for flowback and produced water is adequate
(Abualfaraj et al. 2014; Fan et al. 2014; Kondash et al. 2014; Lester et al. 2015; and Wang et al. 2014),
the organic composition of flowback/produced water is not adequately described within the draft
Assessment Report. This may be because there is a major gap in knowledge of hydraulic fracturing
constituents that are designated as confidential business information (CBI), and that a significant portion
of hydraulic fracturing injection fluid constituents being used by operators are considered proprietary
information. The sphere of unknown constituents is further enlarged by the fact that subsurface reactions
can change the structure and toxicity of both known and unknown constituents. The EPA tried to
express some of that uncertainty in Chapter 8, but certain statements within the chapter on this topic are
confusing, such as the following statement on page 8-11:
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Certain organic compounds are of concern in drinking water because they can cause damage to
the nervous system, kidneys, and/or liver and can increase the risk of cancer if ingested over a
period of time (U.S. EPA 2006). Some organics in chemical additives are known carcinogens,
including 2-butoxyethanol (2BE), naphthalene, benzene, andpolyacrylamide (Hammer and
VanBriesen 2012). Many organics are regulatedfor drinking water under the National Primary
Drinking Water Regulations.
Such statements suggest that if organic constituents do not fall into these categories, then there may not
be a concern regarding such constituents. To address these concerns that the draft Assessment Report
contains limited information on chemical identity and concentrations in hydraulic flowback and
produced water, the agency should acknowledge that there is a lack of information on what is being
injected, and should describe these concerns regarding its reliance on an early version of FracFocus data
within the final Assessment Report. Within the final Assessment Report, the agency should also
characterize in some way data on proprietary constituents that the EPA may have, and information
provided in newer versions of FracFocus on chemical class and concentration (i.e., concentration of the
constituent, in terms of % by mass, in the hydraulic fracturing fluid). As the FracFocus data that the
agency assessed were current up to February 2013, the SAB also recommends that the EPA should
discuss the current status of FracFocus and changes that have been made to the FracFocus platform and
system, and articulate needs for information that is collected and available from individual states and
that could help with assessment yet is not readily accessible.
Treatment Residuals
Regarding the residuals generated from hydraulic fracturing-related wastewater treatment, given the
processes used to remove many of the contaminants discussed in Chapter 8, various contaminants can
become highly concentrated in the residuals. While treatment residuals may contain sufficiently high
concentrations of dissolved metals, TDS, radionuclides, and organics that these residuals could be
classified as hazardous waste under RCRA rules based on their concentrations, residuals associated with
oil and gas operations have an existing exclusion from being considered hazardous waste under RCRA
(EPA 40 CFR 261.4(b)). The final Assessment Report should clarify which specific hydraulic fracturing
wastes (including treatment residuals) are exempt under RCRA, whether management of these wastes is
governed by other federal, state or tribal regulations, and how these wastes are actually managed. Since
hydraulic fracturing treatment residuals and other wastes can be a significant source of leaching of
hazardous chemicals into the environment, if not properly managed, the final Assessment Report should
summarize available information on this topic. If there are no known data sources and these wastes are
simply being disposed of in unknown locations with no records being kept, the EPA should identify this
as a data gap that would impact the ability of the EPA and others to evaluate the impacts of waste
disposal on drinking water resources.
In Table F-2 on page F-15 of the final Assessment Report, "Organics" should be divided into particulate,
liquid, dissolved, and perhaps emulsified states. Mechanisms (and processes) for removing these
different types (states) of organic matter differ greatly, and lumping them together oversimplifies such
mechanisms and processes and will almost certainly cause confusion in the minds of at least some
readers.
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Bromide and Nitrosamines
In Section 8.6.1.2 of the draft Assessment Report, the EPA used modeling to examine strategies for
reducing the impact of bromide on downstream users. The EPA should have included a description of
the model and its assumptions. The agency should reconsider or reassess its use of modeling to
determine definitive strategies for reducing impacts on PWS, since experimental data that were reported
earlier in this section of the draft Assessment Report describe how significant dilution of waters
containing dissolved bromide may not reduce levels to background concentrations.
Although N-Nitrosodimethylamine (NDMA) is mentioned in Appendix F (p. F-28), the discussion there
focuses on the possible role of bromide in forming NDMA and on possible future regulation of NDMA
and other nitrosamines. The potential for hydraulic fracturing wastewaters to form nitrosamines is
otherwise ignored. There is no mention of NDMA in Chapter 8. Considering that (1) hydraulic
fracturing wastewaters may contain high levels of known NDMA precursors (including bromide,
ammonia, and amines), (2) industrial discharges have been found to pose significant problems with
respect to NDMA formation (e.g., for the Orange County (California) Water District's Groundwater
Replenishment System), and (3) disinfection of water and wastewater can potentially result in formation
of problematic levels of NDMA, increased NDMA formation is a potentially significant impact of
hydraulic fracturing wastewater discharges on drinking water resources. The final Assessment Report
should include analyses on the potential for hydraulic fracturing wastewaters to form nitrosamines. Also,
the EPA should further describe how the reported high levels of Total Kjeldahl Nitrogen (TKN) for
some samples (e.g., on p. E-8) are also of concern, since TKN includes nitrogenous organic constituents
that may also be NDMA precursors.
On page F-28, lines 19-20 of the draft Assessment Report, in the discussion on drinking water treatment
at downstream drinking water treatment plants, the text states that: "Studies generally report that the
ratios of halogen incorporation into DBFs reflect the ratio of halogen concentrations in the source
water. " Though technically true, the statement is misleading, in that bromide is preferentially
incorporated into halogenated DBPs, and needs to be revised. The SAB notes that up to half of the
bromide in a given raw water supply may be incorporated into halogenated DBPs during drinking water
treatment at downstream drinking water treatment plants. Bromide is converted (oxidized) to bromine by
the applied disinfectant (e.g., chlorine). The bromine and the chlorine are incorporated into DBPs. The
ratio of bromide to applied chlorine and bromide to organic matter affects the bromination fraction in the
DBPs. The applied chlorine level is determined by the chlorine demand, water temperature and the
required CT (disinfectant concentration x contact time) for the plant. Literature reports have considered
bromide incorporation percentages (Luong et al. 1982; Amy et al. 1991) within THM, while
incorporation into unregulated DBPs is less well studied. The dissolved Br-to-Cl ratio in the DBPs can
be orders of magnitude higher than the ratio in the raw water, (e.g., Hua et al. 2006; Obolensky and
Singer 2005; and Westerhoff et al. 2004).
Antiscalants and Other Constituents
Some hydraulic fracturing wastewaters may contain significant concentrations of antiscalants, if
antiscalants are used in preparation of hydraulic fracturing fluids, and some may contain various
complexing agents used for other purposes besides scale control. Such constituents may, if discharged
into drinking water sources in sufficient amounts, influence the transport and fate of metal ions, and
adversely impact metal ion removal by various treatment processes. The agency should address this
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potential concern in Chapter 8. Data sources that would provide information on concentrations of
antiscalants in HF waters are provided in section d2 below.
In addition, the final Assessment Report should discuss the degree to which bromate, chlorate, chlorite,
perchlorate, and iodate are used in hydraulic fracturing fluids and are present in flowback and produced
water. The SAB notes that bromates, chlorites and hypochlorites are used in fluids during HF
stimulation. All of these constituents have human toxicity endpoints and some have MCLs, and the EPA
should describe whether these constituents are ever found in hydraulic fracturing waters. The SAB also
finds that the EPA's discussion on halogens and halogenated disinfection by-products in Chapter 8 is
inadequate.
Additional Recommended Corrections
The draft Assessment Report includes a number of inaccurate statements regarding treatment
technologies and the removal mechanisms involved, and the SAB recommends that the EPA correct
these statements to address concerns noted below:
• On page 8-38, electrocoagulation is characterized as an "emerging technology. " Perhaps it has only
recently begun to be used (or tested for use) to treat hydraulic fracturing wastewater, but the
technology is a niche technology that has been available for decades. Fundamentally, it is simply
another way to add metal salt coagulants to water, which has been a common water treatment
process for well over a century. Coagulation has long been used to treat wastewaters containing
emulsified oils or small droplets of oil (page 8-68), such as refinery wastewaters. It seems
inappropriate to lump this technology with technologies that are clearly both new and emerging,
such as forward osmosis. Also, the draft Assessment Report notes (page 8-47) that recent tests of
electrocoagulation "illustrated challenges, with removal efficiencies affected by factors such as pH
and salt content. " These challenges have also been well known for many decades. See, for example,
the EPA-600/8-77/005 (Manual of Treatment Technologies for Meeting the Interim Primary
Drinking Water Regulations) for information on the effects of pH and chemical dosage on removal
of selected metal ions in the coagulation process.
• In some places the draft Assessment Report refers to "bromine" whereas in other places the draft
Assessment Report refers to "bromide." The EPA should check that the terms are used appropriately,
in each case referring to the relevant chemical form for the particular context.
• On page 8-46, the draft Assessment Report states that:
TSS can be removed by several processes, such as coagulation, flocculation, sedimentation, and
filtration (including microfiltration and media and bag and/or cartridge filtration), and with
hydrocy clones, dissolved air flotation, freeze-thaw evaporation, electrocoagulation, and
biological aeratedfilters.
The SAB notes that coagulation, flocculation, and electrocoagulation do not "remove" TSS.
Coagulation and electrocoagulation destabilize colloidal particles (often by neutralizing their
charge), allowing them to aggregate into larger particles so they can be aggregated (flocculated) into
larger particles that are more readily removed by processes such as sedimentation, filtration, and
dissolved air flotation.
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• On pages 8-46 and 8-47, the draft Assessment Report states that monovalent ions are not removed
by basic treatment processes and require more advanced treatment such as nanofiltration. The SAB
notes that nanofiltration removes divalent ions well, but typically achieves little or no removal of
monovalent ions.
• On page 8-47, the draft Assessment Report states that "Media filtration can remove metals if
coagulation / oxidation is implemented prior to filtration. " This is a gross oversimplification of the
processes involved. Metals can be present in both particulate and dissolved forms. Those present in
particulate form can often be effectively removed by filtration; but, depending on the characteristics
of the particles and the filter, coagulation and flocculation may be required prior to filtration.
Dissolved metals can be removed by filtration only if they are first incorporated into particles, which
could occur if they are precipitated (e.g., precipitation of barium as BaS04) or adsorbed onto solids
such as iron or aluminum oxides produced by coagulation, various other precipitates, powdered
activated carbon, or adsorptive media. However, only certain combinations are effective.
Furthermore, although oxidation promotes the removal of some metals (such as Fe2+ and Mn2+), it
hinders the removal of chromium by converting it to a more soluble (and more toxic) form (Cr6+).
• On page 8-47, the draft Assessment Report states that "Advanced treatment processes such as ...
nanofiltration can remove dissolved metals and metalloids. " Nanofiltration is expected to be highly
effective only for those dissolved metals present in the form of multivalent ions or large coordination
complexes.
• On page 8-64, the draft Assessment Report states that "Radium ... will also co-precipitate calcium,
barium, and strontium in sulfate minerals. " Radium is present in only trace amounts, but can be co-
precipitated (removed from solution) when a sufficient amount of sulfate is added to precipitate
calcium, magnesium, or barium. Carbonate addition, forming calcium carbonate, would also be
expected to work reasonably well. It may be unlikely that enough radium would ever be present for
it to form a precipitate and for the other metals to then be co-precipitated with radium sulfate. Co-
precipitation, by definition, is the incorporation of a substance into a precipitate when it would have
remained in solution had the precipitate not formed. The SAB suggests that the EPA reword this
sentence to read: "Radium ... can also be removed by co-precipitation if sulfate or carbonate is
added to hydraulic fracturing wastewater to precipitate calcium, barium, or strontium. "
• On page 8-65, the draft Assessment Report states that "Common treatment processes, such as
coagulation, are effective at removing many metals. " As noted above, "coagulation" per se does not
remove metals. Coagulation can facilitate removal of metal-containing particles by neutralizing their
charge, and precipitates formed by metal-salt coagulants can adsorb (co-precipitate) certain metal
ions, depending on the ability of the metal to adsorb to the precipitate and other factors such as pH,
ionic strength, and the presence of competing ions.
• On page 8-66, line 23, aeration is listed as a process able to remove volatile organic compounds
(VOCs). Although the term "aeration" is often used to describe this process, it is more accurately
referred to as "air stripping." In wastewater treatment, aeration refers to the mixing of air/oxygen,
through mechanical processes, in wastewater.
• On page F-7, electrocoagulation is said to be "... less effective for removing TDS and sulfate. " This
technology is not effective at all for removing TDS and sulfate, nor is any other coagulation process,
except perhaps under extreme conditions one would not expect to encounter in practice. Any
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incidental removal associated with changes in pH or ionic composition could be just as readily and
less expensively obtained simply by adding an appropriate acid, base, or salt. Electrocoagulation is
correctly characterized in Table F-2, page F-15, as "not effective" for TDS and anion removal; and it
"removes" TSS and organics only to the extent that coagulated solids (including organic solids), and
dissolved organics coprecipitated with the coagulated solids, are removed by subsequent treatment
processes that remove particles.
• On page F-9, the draft Assessment Report notes that electrodialysis relies on "positively and
negatively charged particles and coated membranes to separate contaminants from the water. " This
statement is incorrect. The process relies on positive and negative charges (provided by electrodes,
not particles) that repel or attract anions and cations, causing them to pass through anion and cation
exchange membranes, respectively. Stacks of these membranes (alternating cation and anion
exchange membranes) separate the water into channels alternately enriched with dissolved solids or
depleted. The channels are segregated and manifolded together to produce a concentrate (brine)
stream and a fresh demineralized (product water) stream.
• On page F-10, the draft Assessment Report states: "Forward osmosis, an emerging technology for
treating hydraulic fracturing wastewater, uses an osmotic pressure gradient across a membrane to
draw the contaminants from a low osmotic solution (the feed water) to a high osmotic solution. "
This is incorrect. Only water passes through the membrane, not salts. The water is drawn into the
"high osmotic solution," which is made using a volatile salt such as ammonium carbonate that can
be driven off with heat, leaving behind pure water. The volatile salt is then condensed and reused.
• In Table F-2, page F-16, the draft Assessment Report indicates that electrodialysis (ED) is very
effective for removing organics. However, this technology is very ineffective for nearly all organics.
Particulate organics, oil and grease, and high molecular weight organic anions foul ED membranes
(which are ion-exchange membranes), either ruining them or significantly shortening their life. Only
small, charged organic ions could be removed, but removal would probably be rather poor in most
cases.
• Throughout the draft Assessment Report, the EPA refers to centralized waste treatment (CWT) and
CWTFs. In these discussions the EPA is describing centralized wastewater treatment facilities. For
clarity, the EPA should redefine both abbreviations noting that "wastewater" is being addressed in
these scenarios, and use these terms consistently throughout the final Assessment Report.
3.6.2. Major Findings
bl. Are the major findings concerning wastewater treatment and disposal fully supported by the
information and data presented in the assessment?
Certain major findings concerning hydraulic fracturing-related wastewater treatment and disposal are
not fully supported by the information and data presented in Chapter 8. The available information and
data do not support the conclusion in the chapter (page 8-75) that "there is no evidence that these
contaminants have affected drinking water facilities. " This conclusion is not fully supported by the
information and data presented in Chapter 8, and is also not supported by peer reviewed literature that
has demonstrated contaminants from oil and gas wastewater disposal facilities have reached drinking
water facilities and have had effects (e.g., see States et al. 2013, which is cited in the draft Assessment
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Report; and Landis et al. 2016). The agency should clearly and accurately describe the basis for this
statement in Chapter 8.
In addition, page 8-68 of the draft Assessment Report describes the "Summary of Findings," and begins
with the statement that: "Hundreds of billions of gallons of wastewater are generated annually in the
United States by the oil and gas industry. " This statement is qualified, and the limitations of the
methodologies are explained, in part, in Section 8.2.3 (page 8-9). However, Chapter 8 of the final
Assessment Report should clearly and accurately describe the basis for this estimate. The draft
Assessment Report includes many disparate estimates (for different years or time periods, different
groups of states, and different segments of the industry) and uses different units of volume and flowrate.
These are appropriately used, but are nevertheless likely to be confusing to at least some readers. To
provide more clarity, the SAB recommends that the EPA include a table in Chapter 8 that illustrates the
basis for this particular estimate, since it is arguably a "major finding." Such a table could perhaps
include reasonable estimates derived from several sources, including correction factors applied to adjust
for increased production over time and for other factors, and the range of estimates from which the
"hundreds of billions of gallons" estimate emerged. In addition, the EPA should provide a validated
approach to predict future hydraulic fracturing-related wastewater generation trends and describe
uncertainty in these predictions.
On page 8-70, line 29, of the draft Assessment Report, in the discussion on drinking water treatment at
downstream drinking water treatment plants, the text notes that bromide is of "concern due to the
formation of disinfection by-products (DBFs)." The SAB notes that bromide does not simply form
DBPs; it also increases both the rate and extent of Trihalomethane (THM) and Haloacetic Acid (HAA)
formation. The draft Assessment Report states on page 8-60 that "... brominatedandiodinated[DBPs]
are considered more toxic than other types of DBPs (Richardson et al. 2007'f and on page 8-70 that
"Brominated DBPs (and iodinated DBPs) are more toxic than other species of DBPs. " The final
Assessment Report should clarify whether these statements are based on toxic effects observed in cell
cultures, on animal toxicity studies, or on human toxicity data. The EPA should cite the appropriate
references for human toxicity data. For example, extensive information regarding the human health
impacts of DBPs is provided within the EPA's Stage 1 and Stage 2 Disinfectants and DBP rules (U.S.
EPA 1998, and U.S. EPA 2006) as well as numerous EPA documents (e.g., U.S. EPA 2005).
On page 8-72, lines 3-4, the draft Assessment Report states: "There may be consequences for
downstream drinking water systems if the sediments are disturbed or entrained due to dredging or flood
events. " The EPA should more clearly summarize these consequences, and provide an example or two
to clarify this statement. Since water treatment plants are typically well equipped to remove suspended
solids, and since the sediments would already have been sitting in water for an extended period of time
(such that hazardous chemicals soluble in water would already have had an opportunity to leach out of
them), the EPA should assess and describe how such entrained or disturbed sediments may have
potentially adverse impacts on drinking water quality.
b2. Do these major findings identify the potential impacts to drinking water resources due to this stage
of the HFWC?
Potential impacts to drinking water resources are not adequately addressed in Chapter 8. The EPA
should describe potential impacts from other DBPs besides THMs and HAAs that are produced in
drinking water treatment when intake water contains some amount of hydraulic fracturing wastewater.
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Deep well injection systems for oil and gas wastewater disposal are not uniformly distributed among the
different states or within states. The draft Assessment Report did not consider several issues associated
with this wastewater disposal method. First, transport of wastewater from a specific wellsite to a
disposal injection well poses risks for spills. Longer distances increase the likelihood of crossing surface
waters, where spills could impact surface water intakes, and the likelihood of spills in general, which
could impact water supply wells. Second, the final Assessment Report should summarize the extent to
which permitting of injection wells in different states considers their proximity and potential impacts to
water supplies (public water supply wells, private wells, surface water intakes). Third, as noted in the
draft Assessment Report on pages ES-19, ES-20, and 8-20, the EPA did not investigate water quality
issues nor potential impacts to drinking water from the disposal of hydraulic fracturing wastewater in
underground injection control wells; the EPA should assess the potential for such issues and impacts as a
longer-term future activity.
An additional concern about injection wells for oil and gas wastewater disposal is their potential impact
on seismic activity and the resulting impacts on the surrounding drilling infrastructure. The draft
Assessment Report does not mention anything about reporting of seismic activity discussed in the very
recent literature (Ellsworth 2013; Yeck et al. 2015; Weingartern et al. 2015; McNamara et al. 2015)
related to deep well injection. The SAB recommends that the EPA include discussion on this issue in
Chapter 8, and assess how the potential for seismic activity may affect operator selection of appropriate
flow rates and pressures to minimize or eliminate significant seismic events when deep well injection is
used. The SAB encourages the agency to collaborate with other federal, state or tribal regulatory
agencies, universities, industry and other stakeholders to update the research associated with this issue as
a longer-term future activity.
HF flowback and produced waters are not always considered "wastewater" since they may be
beneficially reused in the HFWC process. The final Assessment Report should note that reuse of
wastewater or HF flowback and produced waters to prepare hydraulic fracturing fluids may significantly
increase the concentrations of various contaminants (e.g., TDS and radionuclides) in both the flowback
and produced water. This would especially occur if the reused water is only partially diluted/treated or if
new hydraulic fracturing fluid technologies that can tolerate significantly higher TDS concentrations are
utilized (which could possibly alleviate the need to even partially treat wastewater before it is reused).
The final Assessment Report should note that the storage of any reused water with these elevated
contaminant concentrations represents a potential source of leaks/spills that could impact local drinking
water resources.
Chapter 8 of the draft Assessment Report cites limited studies that investigated radionuclides in effluents
from POTWs, CWTFs, and zero-liquid-discharge facilities. Based on the reporting of the data, the EPA
noted that POTWs receiving wastewater from hydraulic fracturing-related CWTFs did not show higher
effluent radionuclide concentrations than POTWs not receiving such waste streams. However, the final
Assessment Report should note that the reported concentrations were all significantly elevated above the
MCLs and several orders of magnitude above background river levels. In addition, the final Assessment
Report should further describe that technologically-enhanced naturally occurring radioactive materials
(TENORM) may pose a significant risk since treatment processes used to remove other constituents
(such as metals, biochemical oxygen demand, or TDS) from these hydraulic fracturing wastewaters may
not remove radionuclides to levels that are protective of public health (depending on the influent
concentration). While the draft Assessment Report does mention these topics, it should emphasize these
as topics of significant concern. The final Assessment Report should also acknowledge that other
strategies for disposal of treated wastewater from hydraulic fracturing-related activities include deep
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well injection and reuse, and that these strategies also have similar concerns with respect to spills and
leaks.
The draft Assessment Report does not provide sufficient discussion on where residuals from zero liquid
discharge facilities or reuse facilities end up, and should add to the discussion on this topic. Since these
residuals concentrate many water soluble pollutants that could find their way into drinking water
resources if not properly managed, the final Assessment Report should clearly and accurately summarize
available information regarding the regulatory framework applicable to these wastes. Data sources that
would provide information on fate of residuals from zero liquid discharge facilities or reuse facilities are
provided in section d2 below.
Chapter 8 provides a limited review of the different unit processes that can be used to reduce various
types of pollutants known to be commonly present in hydraulic fracturing flowback water and produced
water (Table 8-6). Since not all constituents in HF Flowback and produced waters are known, the
chapter should recognize that there are no data on the removal of unknown hydraulic fracturing
constituents, and that the presence of these unknown constituents results in a significant amount of
uncertainty in the selection of a management strategy that involves discharges into a drinking water
resource, land application, or road spreading.
To help assess the potential impacts of hydraulic fracturing wastewaters on drinking water resources, the
EPA should consider mapping all regulated injection well sites in the United States relative to locations
of intakes for drinking water treatment plants, and the locations of domestic wells. Inclusion of such
maps with a corresponding analysis within the final Assessment Report would strengthen the
examination of the potential impacts of hydraulic fracturing wastewaters on drinking water resources.
h3. Are there other major findings that have not been brought forward?
Chapter 8 of the draft Assessment Report did not bring forward all the major findings associated with
the wastewater treatment and waste disposal phase of the HFWC. The draft Assessment Report does not
mention that elevated radionuclide concentrations are likely to be present in the effluents from some
CWTFs and most POTWs treating hydraulic fracturing-related wastewaters. The study that the draft
Assessment Report cited as evidence of significant removal of radionuclides used data from another
study, and not direct evidence, to estimate removal. The draft Assessment Report notes that effluent
radium concentrations from CWTFs and zero-discharge facilities were on the order of thousands of
pCi/L. The SAB is concerned that the zero discharge facilities that will produce water for reuse will
have extremely high radium concentrations that will consequently pose an elevated risk if leaks or spills
of these reuse waters occur. Within the draft Assessment Report, the EPA describes a study that
assumed a 3-log (lOOOx) reduction in radium concentration using co-precipitation with barium sulfate.
However, this cited study did not actually measure the influent concentration. The SAB recommends
that the EPA include an assessment of the potential accumulation of radium in pipe scales, sediments,
and residuals; the potential for leaching of this radium into drinking water resources; and the potential
impacts of such leaching.
The use of CWTFs is a management strategy to reduce the pollutant load from flowback and produced
wastewater. While Chapter 8 discusses the unit processes typically used at these facilities, the final
Assessment Report should further describe that these processes may not be able to reduce the
concentrations to levels that allow for discharge to a drinking water resource. Examples of constituents
and discharge limits specified in NPDES discharge permits for CWTFs would be informative to include.
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Due to the non-disclosure of constituents used in hydraulic fracturing injection fluids and to unknown
subsurface reactions that affect the quality of flowback and produced water, the final Assessment Report
should address directly the extent to which the EPA can assess whether the effluent water from CWTFs
is treated to a level that provides sufficient environmental and public health protection. An additional
point regarding the discussion of CWTFs is that many of the descriptions of unit processes used are very
general and sometimes incorrect. As discussed in the response to Charge Question 4a, these descriptions
should be corrected.
The final Assessment Report should also assess iodide in the same manner as is recommended for
bromide (see the response to sub-question bl above), even though the draft Assessment Report provides
very little data on the presence of iodide in flowback or produced waters. During drinking water
treatment at downstream drinking water treatment plants, iodide also reacts with some oxidants to
produce DBPs, and recent evidence shows that brominated and iodinated DBPs are more cyto- and
geno-toxic than the chlorinated analogs (Plewa et al. 2009). Therefore, information about iodide in
flowback or produced waters should be amplified in the final Assessment Report. The ratio of dissolved
Cl/I in Table E-4 is around 5000/1, which is much lower (i.e., more iodide) than the ratio in seawater,
which is 35,000/1. The EPA should discuss why iodide is more concentrated in flowback and produced
water relative to chloride than in seawater.
3.6.3. Frequency or Severity of Impacts
b4. Are the factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
Chapter 8 does not adequately address the potential frequency and severity of impacts of hydraulic
fracturing wastewater treatment and waste disposal on drinking water quality, nor potential scenarios in
the near future that could influence such impacts (e.g., reduced access to deep well injection due to
restrictions associated with seismic activity). The EPA should more clearly describe the potential
frequency and severity of impacts associated with the wastewater treatment and waste disposal stage in
the HFWC, before drawing conclusions on water quality impacts associated with this stage of the
HFWC. Factors affecting the frequency or severity of potential impacts are not adequately described for
either private wells or municipal water systems.
There is inadequate information and analysis in the draft Assessment Report, including Appendix E,
related to bromide and iodide. Bromide is important for drinking water because upon addition of
oxidants or disinfectants (chlorine, ozone) brominated disinfection by-products form in drinking water
(e.g., brominated THMs and HAAs, bromate). The ratio of dissolved CI/Br in Table E-4 is roughly
200/1, which is lower than the ratio in seawater (-300/1) and lower than the -300/1 ratio observed in an
American Water Works Association (AWW A) national survey of bromide in drinking waters (Amy, G.
1994). The EPA should describe the reasons for elevated bromide in these flowback and produced
waters, relative to chloride, and further describe the severity of impacts associated with bromide in these
waters.
Additional data should be referenced regarding DBP formation in drinking water treatment plants
downstream from CWTFs or from POTWs receiving hydraulic-fracturing related wastewater. For
example, the State of Pennsylvania's public drinking water suppliers have been reporting full speciation
data on THM and HAA in compliance data for several years. Also, the EPA's Region 3 office is
conducting an ongoing study of bromide and DBPs in the Ohio River. The final Assessment Report
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should discuss the fluctuations in total organic halide (TOX) at water treatment plants downstream from
CWTFs and from POTWs receiving discharges of hydraulic fracturing-related wastewater, since
upstream POTWs and CWTFs likely receive pulses or extended releases of high salinity water.
The final Assessment Report should also describe the NPDES permits for CWTFs and POTWs
receiving hydraulic-fracturing related wastewater, and note whether these permits regulate based upon
grab samples. The EPA should also describe whether impacted POTWs are required to install and/or
would benefit from installation of real-time conductivity meters. The SAB notes that pulses of Br", I" or
other salts to downstream WTPs can lead to pulses of DBPs in distribution systems. This is relevant
because the EPA recognizes the potential for acute health risks to sensitive populations (e.g., pregnant
women) from exposure to high levels of DBPs.
Naturally occurring organic matter (NOM), typically measured as TOC or DOC, is a well-known major
precursor for formation of a broad spectrum of disinfection by-products in drinking water treatment,
including THMs and HAAs. Hydraulic fracturing wastewater can contain very high levels of TOC (e.g.,
as indicated by the data shown on pages E-9, E-25, and E-27). The draft Assessment Report
inadequately describes the potential for the organic matter in hydraulic fracturing wastewater to form
THMs, HAAs, and other by-products during drinking water treatment at downstream drinking water
treatment plants, and when present in PWS intake water and subjected to oxidation treatment for
disinfection, which could be readily evaluated using simple DBP formation potential tests. The EPA
previously noted that research on the DBP formation potential of hydraulic fracturing-related
wastewaters was important to conduct, as described in the EPA's research Study Plan (U.S. EPA 2011),
and the SAB recommends that the EPA describe these issues in the final Assessment Report. The SAB
recognizes that there is relatively little published data on concentrations of TOC/NOM found in HF-
related wastewaters, its UV absorbance (an indicator of precursor strength), and the extent to which it
forms DBPs (i.e., is it strong, weak, average, or highly variable compared to other sources of
precursors). The EPA should include any available data on TOC/NOM and ammonium concentrations in
HF-related wastewater in the final Assessment Report and note that these concentrations are a factor that
may influence the potential impacts of HF on drinking water resources. The SAB also notes that the
apparent lack of such data is a serious data gap and the EPA should prioritize this as a research need as a
longer-term future activity. Data sources that would provide information on DBPs are provided in
section d2 below.
HF wastewaters can contain high concentrations of ammonium (e.g., as shown on page E-7), which can
interfere with drinking water treatment by increasing chlorine demand and by converting free chlorine to
chloramines. The latter poses a significant risk to human health if the water treatment plant operators are
not aware that ammonium is present and therefore assume that the chlorine they add will be present as
free chlorine rather than combined chlorine; the final Assessment Report should describe this scenario.
Also, the final Assessment Report should mention the chlorine demand associated with hydraulic
fracturing wastewaters, which if significant could also adversely impact drinking water treatment plants.
Data sources that would provide information on HF wastes with high ammonium levels, resulting in the
formation of chloramines, are limited. However, citations for high ammonia and chloramine chemistry
are provided in section d2 below.
Strontium (Sr) is mentioned a number of times in Chapter 8. The draft Assessment Report lacked
discussion of the EPA's plans to regulate (establish an MCL for) dissolved Sr in drinking water, as the
agency announced in 2014. The current Health Reference Level is only 4 mg/L. Since hydraulic
fracturing wastewater can contain hundreds to over a thousand mg/L of Sr (page 8-65), discharge of
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even a small amount of inadequately treated hydraulic fracturing wastewater to a drinking water source
could compromise a water utility's ability to comply with the anticipated MCL for strontium. The
frequency and severity of impacts associated with strontium in hydraulic fracturing wastewaters should
be acknowledged in the final Assessment Report.
3.6.4. Uncertainties, Assumptions and Limitations
c. Are the uncertainties, assumptions, and limitations concerning wastewater treatment and waste
disposal fully and clearly described?
Chapter 8 of the draft Assessment Report does not fully and clearly describe uncertainties, assumptions,
and limitations concerning wastewater treatment and waste disposal.
CWT unit processes and disposal techniques have changed significantly over the past 15 years, and are
likely to continue changing. The draft Assessment Report does not adequately describe past trends or
anticipated future developments in treatment of produced water, nor does it adequately address future
uncertainties. For example, the final Assessment Report should describe where hydraulic fracturing-
related wastewaters would likely end up if significant seismic activity leads to curtailment of deep well
injection of wastes (as recently occurred in Oklahoma; see Wines 2016), and what will be done with
produced waters that are recycled if well drilling slows and there is less demand for recycled water for
hydraulic fracturing. The SAB recommends a more detailed analysis of these trends, including actual
and projected disposal costs, as a longer-term future activity.
A key limitation of Chapter 8 is that, although this chapter addresses potential impacts of hydraulic
fracturing-related wastewater treatment and disposal from a watershed perspective, especially in Section
8.6, the chapter should put into a watershed perspective CWTFs discharging to surface waters or
POTWs (Table 8-4, page 8-24), and other treatment and disposal facilities, such as disposal wells.
Chapter 3 provided information regarding the number of PWSs within 1 mile of a hydraulically
fractured well. Such information can be useful in assessing the potential impacts of spilled liquids and
migration through faults, especially if viewed in a three-dimensional setting. Additional analyses of this
type for the range of facilities noted in Chapter 8 would provide more insight into risks to drinking water
resources.
Chapter 8 inadequately describes potential impacts on public drinking water supplies that rely upon
surface water intakes located within the same watershed as, but downstream of, hydraulic fracturing
activities or discharges of hydraulic fracturing wastewaters. Many drinking water systems rely upon
surface water supplies which could be located many miles downstream of hydraulic fracturing sites, but
subject to potential impacts from hydraulic fracturing wastewater discharges (e.g., States et al. 2013,
which is cited in the draft Assessment Report). To assess this topic, a variety of information is needed
including: the size and location of injection wells, CWTFs, and POTWs receiving wastewater discharges
(directly or indirectly); the locations and treatment capabilities of drinking water treatment facilities; and
the locations of streams and lakes and their flowrates and volumes, respectively. There are relatively few
CWTFs known to be discharging to surface waters or POTWs (Table 8-4), and the EPA should provide
information on the contributions that CWTFs may make to TDS, regulated contaminants, and other
contaminants of concern in downstream PWSs. The EPA should also provide similar information for
any POTWs known to be accepting wastewater associated with hydraulic fracturing.
The EPA should also consider the potential impact that treatment of any hydraulic fracturing fluids
would have on the ability of a local POTW to recover resources (energy, water, nutrients) from
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wastewater. This is important because the EPA, DOE, other federal agencies, and some professional
organizations have been organizing meetings on accelerating this aspect of the wastewater sector. In
addition, the SAB notes that some POTWs are operated 24 hours per day while others are staffed only
during day time operating hours, and recommends that the EPA consider the impact that treatment of
any hydraulic fracturing fluids would have on local POTWs in terms of their staffing levels and operator
training.
On page 8-70 of the draft Assessment Report, the summary of findings states that modeling suggests
that small percentages of hydraulic fracturing wastewater in a river may cause a notable increase in DBP
formation in a drinking water treatment plant. Experimental data from a literature study described that
effect. Modeling was used to propose and evaluate strategies for diluting bromide to lessen impacts on
downstream drinking water resources. The EPA's use of modeling is not adequately supported, as
inadequate information is provided regarding the modeling approach, parameters involved, assumptions
made, and whether any sensitivity or uncertainty analysis was performed to estimate the probable range
of possible answers. The EPA should explicitly describe this information within the final Assessment
Report. If these modeling results are included in the final Assessment Report, the limitations associated
with the modeling should be explicitly identified and the results should be appropriately qualified in the
final Assessment Report.
In the uncertainty section (8.7.3) of Chapter 8, it is stated on page 8-73 that limited monitoring data may
be available from CWTFs with NPDES permits. Although the draft Assessment Report notes that
monitored data for certain constituents may be limited, the discharge permit holders may not test for
even a small fraction of the constituents found in hydraulic fracturing-related wastewater. The EPA has
not and should present monitoring requirements and analyses associated with NPDES permits for
CWTFs and evaluate the extent to which existing permits protect drinking water resources from
hydraulic fracturing-related wastewater discharges from CWTFs or POTWs.
The final Assessment Report should describe the treatment capacity (in millions of gallons per day,
MGD) of the CWTFs identified in Table 8-4, relative to the annual produced water volume within a
fixed distance (e.g., 100 miles). The EPA should also provide adequate justification for limiting analysis
to a one mile radius to define proximity of a drinking water resource to hydraulic fracturing operations.
The SAB notes that the EPA used a five mile radius for potential effects of coal-fired power plant
bromide discharges on downstream drinking water plants (U.S. EPA 2015b). While it is not clear that
the five mile radius is sufficient as the discharged bromide is conservative in surface waters, some
consistency in the proximity analysis for different sources of the same contaminant (bromide) may be
expected.
The EPA should also develop maps of watersheds that have drinking water treatment plants located
downgradient from active or planned hydraulic fracturing activities for oil or gas development. Limiting
proximity analysis to one mile results in considerable uncertainty associated with potential impacts to
drinking water resources. A Geographic Information System (GlS)-based research method is available
that can be used to estimate the number of drinking water treatment plants with upstream municipal
wastewater discharges (Rice et al. 2015; Rice and Westerhoff 2015). The EPA should conduct similar
work to understand potential risks to municipal surface water drinking water intakes greater than one
mile away from hydraulic fracturing-related treatment and disposal facilities.
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3.6.5. Information, Background or Context to be Added
dl. What additional information, background, or context should be added, or research gaps should be
assessed, to better characterize any potential impacts to drinking water resources from this stage of the
HFWC?
The EPA should include results from or status of research described in the final Study Plan (U.S. EPA
2011) and the EPA's December 2012 Progress Report (U.S. EPA 2012). Specifically, this includes the
results of laboratory experiments to simulate wastewater treatment processes to assess their ability to
remove a range of pollutants, such as radionuclides, VOCs, anions, metal cations, and inorganics, as
well as DBP formation potential tests on hydraulic fracturing fluids, produced waters, and treated and
untreated hydraulic fracturing-related wastewaters. While a limited number of such tests were performed
in studies cited in the draft Assessment Report, the SAB recommends that the EPA conduct these
additional research efforts.
The draft Assessment Report also includes little or no information on, or discussion of, several
important DBPs (including bromate and nitrosamines such as NDMA) and stakeholder activities (e.g.,
Technical Workshop 2011, Technical Roundtable 2012, Technical Workshop 2013), and this
information should be described within the final Assessment Report.
The draft Assessment Report concludes, in its summary of findings on page 8-68 that Hundreds of
billions of gallons of wastewater are generated annually in the United States by the oil and gas industry.
While this statement is qualified in the text and its limitations are explained in part in Section 8.2.3 on
page 8-9 of the draft Assessment Report, the EPA should provide a more clear explanation of the basis
for this estimate. The EPA also should more clearly and consistently describe the estimates that are
provided on this topic in various different locations within the final Assessment Report, and consistently
describe units of volume and flowrate. This statement, unlike other statements in the draft Assessment
Report, applies to the entire oil and gas industry rather than unconventional hydraulically fractured
wells; the draft Assessment Report explains that it was difficult to come up with an estimate pertaining
specifically to unconventional wells, but the draft Assessment Report appears to include sufficient
information to allow such an estimate to be made.
Also, based on the title of this chapter, Chapter 8 addresses both hydraulic fracturing-related wastewater
treatment and waste disposal. While the draft Assessment Report does briefly address hydraulic
fracturing-related wastewater treatment residuals, the draft Assessment Report provides little
information regarding other wastes associated with hydraulic fracturing such as drill cuttings and
drilling muds, and their potential to impact drinking water resources, and the SAB finds that it should
provide more information and analyses on these topics.
d2. Are there relevant literature or data sources that should be added in this section of the report?
The SAB recommends that the EPA consider the following additional literature sources within this
chapter of the final Assessment Report:
References on seismic activity
• Ellsworth, W.L. 2013. Injection-induced earthquakes. Science 341(6142). July 12, 2013. doi:
10.1126/science. 1225942.
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• McNamara, D.E., H.M. Benz, R.B. Hermann, E.A. Bergman, P. Earle, A. Holland, R. Baldwin,
and A. Gassner. 2015. Earthquake hypocenters and focal mechanisms in central Oklahoma
reveal a complex system of reactivated subsurface strike-slip faulting. Geophysical Research
Letters 42(8), p. 2742-2749. doi: 10.1002/2014GL062730.
• Weingartern, M., S. Ge, J.W., Godt, B.A. Bekins, and J.L. Rubinstein. 2015. High-rate injection
is associated with the increase in U.S. mid-continent seismicity. Science 348(6241), p. 1336-
1340. June 19, 2015. doi: 10.1126/science.aabl345.
• Yeck, W.L., L.V. Block, C.K. Wood, and V.M. King. 2015. Maximum magnitude estimations of
induced earthquakes at Paradox Valley, Colorado, from cumulative injection volume and
geometry of seismicity clusters. Geophys. J. Int. 200(1), p. 322-336. January 2015. doi:
10.1093/gji/ggu394.
References on energy in treatment plants
• McGucken, R., J. Oppenheimer, M. Badruzzaman, and J. Jacangelo. 2013. Toolbox for water
utility energy and greenhouse gas emission management. Sponsored by the Water Research
Foundation, Global Water Research Coalition, andNYSERDA. Water Resource Foundation.
Denver, Colorado.
• U.S. EPA (U.S. Environmental Protection Agency). 2013. Energy efficiency in water and
wastewater facilities: a guide to developing and implementing greenhouse gas reduction
programs, EPA-430-R-09-038.
http://www3.epa.gov/statelocalclimate/documents/pdf/wastewater-guide.pdf
References on bromides
• Amy, G., L. Tan, and M. Davis. 1991. The effects of ozonation and activated carbon adsorption
on trihalomethane speciation. Water Research 25(2): 191-202.
http ://www. sciencedirect.com/sci ence/arti cl e/pi i/0043 13549190029P
• Amy, G., M. Siddiqui, W. Zhai, J. DeBroux, and W. Odem. 1994. American Water Works
Association Research Foundation (AwwaRF) Final Report - Survey on bromide in drinking
water and impacts on DBP formation. American Water Works Association Research Foundation.
• Luong, T., C. Peters, and R. Perry. 1982. Influence of bromide and ammonia upon the formation
of trihalomethanes under water-treatment conditions. Environmental Science and Technology
16(8): 473-479. http://pubs.acs.org/doi/abs/10.1021/esOO 102a009'?iournalCode=esthag
• U.S. EPA (U.S. Environmental Protection Agency). 2015b. Effluent Limitations Guidelines and
Standards for the Steam Electric Power Generating Point Source Category. United States
Environmental Protection Agency EPA-HQ-OW-2009-0819, Washington DC.
https://vvvvvv.epa.gov/eg/steam-electric-povver-generating-eft1uent-guidelines-2015-final-rule
• Weaver, J., J. Xu, and S. Mravik. 2016. Scenario Analysis of the Impact on Drinking Water
Intakes from Bromide in the Discharge of Treated Oil and Gas Wastewater. ASCE Journal of
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Environmental Engineering 142(1). DOI:
http://ascelibrarv.oru/doi/abs/10.1061 / % 2 8 A S C E% 2 9 E E. 1943-7870.0000968
References on concentrations of antiscalants in HF waters
• There are many websites with information from vendors on what they sell and why (e.g.,
http://www.aimgroup.com.au/pdf/1207%20BWA oil seam gas chemicals.pdO. FracFocus
would presumably be one good source of data, since antiscalants are considered a common
ingredient in hydraulic fracturing fluids. Here are three of many journal publications:
• Lester, Y., I. Ferrer, E.M. Thurman, K.A. Sitterley, J.A Korak, G. Aiken, and K.G Linden. 2015.
Characterization of hydraulic fracturing flowback water in Colorado: Implications for water
treatment. Science of the Total Environment 512: p. 637-644.
• Ferrer, I. and E.M. Thurman, Analysis of hydraulic fracturing additives by LC/Q-TOF-MS.
Analytical and Bioanalytical Chemistry, 2015. 407(21): p. 6417-6428.
• Thurman, E.M., I. Ferrer, J. Blotevogel, and T. Borch. 2014. Analysis of hydraulic fracturing
flowback and produced waters using accurate mass: identification of ethoxylated surfactants.
Analytical Chemistry 86(19): p. 9653-9661.
References on fate of residuals from zero liquid discharge facilities or reuse facilities
If disposal of these wastes is regulated, e.g., under RCRA, then the reporting requirements may identify
the relevant data source. While the SAB Panel could not locate specific documentation on zero liquid
discharge technologies for HF activities, the following publications on zero liquid discharge
technologies for other applications should be useful to the EPA as it summarizes these technologies:
• Badruzzaman, M., J. Oppenheimer, S. Adham, and M. Kumar. 2009. Innovative beneficial reuse
of reverse osmosis concentrate using bipolar membrane electrodialysis and electrochlorination
processes. J. Membrane Sci. 326(2): p. 392-399.
• Ji, X., E. Curcio, S. A1 Obaidani, G. Di Profio, E. Fontananova, and E. Drioli, 2010. Membrane
distillation-crystallization of seawater reverse osmosis brines. Separation and Purification Tech.
71(1): p. 76-82.
• Kim, D.H. 2011. A review of desalting process techniques and economic analysis of the recovery
of salts from retentates. Desalination 270(1-3): p. 1-8.
• Martinetti, C.R., A.E. Childress, and T.Y. 2009. Cath, High recovery of concentrated RO brines
using forward osmosis and membrane distillation. J. Membrane Sci. 331(1-2): p. 31-39.
• Perez-Gonzalez, A.M., R. Urtiaga, and I. Ibanez. 2012. State of the art and review on the
treatment technologies of water reverse osmosis concentrates. Water Research 46(2): p. 267-283.
• Zhao, S., L. Zou, and D. Mulcahy. 2012. Brackish water desalination by a hybrid forward
osmosis-nanofiltration system using divalent draw solute. Desalination 284: p. 175-181.
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References on DBPs
There are hundreds of publications on DBPs, here are a few representative publications:
• Archer, A.D. and P.C. Singer. 2006. An evaluation of the relationship between SUVA and NOM
coagulation using the ICR database. J. American Water Works Assn. 98(7): p. 110-123.
• Hsu, S. and P.C. Singer. 2010. Removal of bromide and natural organic matter by anion
exchange. Water Research 44(7): p. 2133-2140.
• Singer, P.C. 1994. Control of disinfection by-products in drinking water. Journal of
EnvironmentalEngineering-ASCE 120(4): p. 727-744.
• U.S. EPA (U.S. Environmental Protection Agency). 1998. National Primary Drinking Water
Regulations: Stage 1 Disinfectants and Disinfection Byproducts Rule. 63 FR 69390-69476,
December 16, 1998. https://www.gpo.gov/fdsvs/pkg/FR-1998-12-16/pdf/98-32887.pdf#page= 1
• U.S. EPA (U.S. Environmental Protection Agency). 2005. Drinking Water Criteria Document for
Brominated Trihalomethanes. 2005. United States Environmental Protection Agency: EPA-822-
R-05-011. Washington DC.
• U.S. EPA (U.S. Environmental Protection Agency). 2006. National Primary Drinking Water
Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule. 71 FR 388-493, January 2,
2006. https://www.gpo.gov/fdsvs/pkg/FR-2006-01-04/pdf/Q6-3.pdf
References on ammonia and chloramine chemistry
• Hayes-Larson, E.L. and W.A. Mitch. 2010. Influence of the method of reagent addition on
dichloroacetonitrile formation during chloramination. Env. Sci. & Tech. 44(2): p. 700-706.
• Mitch, W.A. and D.L. Sedlak. 2002. Formation of N-nitrosodimethylamine (NDMA) from
dimethylamine during chlorination. Env. Sci. & Tech. 36(4): p. 588-595.
• Schreiber, I.M. and W.A. Mitch. 2005. Influence of the order of reagent addition on NDMA
formation during chloramination. Env. Sci. & Tech. 39(10): p. 3811-3818.
• Schreiber, I.M. and W.A. Mitch. 2005. Influence of chloramine speciation on NDMA formation:
Implications for NDMA formation pathways. Abstracts of Papers of the American Chemical
Society 230: p. U1503-U1504.
Additional resources:
• Jackson, R.B., E.R. Lowry, A. Pickle, M. Knag, D. DiGiulio, and K. Zhao. 2015. The depths of
hydraulic fracturing and accompanying water use across the United States. Environ. Sci.
Technol. 49(15), p. 8969-8976. doi: 10.1021/acs.est.5b01228.
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Rice, J., S. Via, and P. Westerhoff. 2015. Extent and impacts of unplanned wastewater reuse in
U.S. Rivers. Journal American Water Works Association, 107, p.11:93 In Press, doi:
10.5942/jawwa.2015.107.0178.
Rice, J. and P. Westerhoff. 2015. Spatial and temporal variation in de facto wastewater reuse in
drinking water systems across the USA. Environ. Sci. & Tech. 49(2), p. 982-989. January 20,
2015. doi: 10.1021/es5048057.
Thorp, L.W., and J. Noel. 2015. Aquifer exemptions: program overview and emerging concerns.
Journal of the American Water Works Association 107(9), p. 53-59. September 2015. doi:
http://dx.doi.org/10.5942/iawwa.2015.107.0138.
U.S. EPA-a (U.S. Environmental Protection Agency). 1979. Estimating water treatment costs,
volume 1 - summary. EPA-600/2-79-162e. 1979.
http://nepis.epa.gov/Exe/ZvNET. ex e/30000909.TXT?ZvActionD=ZyDocument&Client=EPA&I
ndex= 1976+Thru+1980&Docs=&Ouerv=&Time=&EndTime=&SearchMethod= 1 &TocRestrict
=n&Toc=&TocEntrv=&QField=&QFieldYear=&QFieldMonth=&QFieldDav=&lntQFieldOp=0
&ExtOFieldOp=0&XmlQuerv=&File=D%3A%5Czvfiles%5CIndex%20Data%5C76thru80%5C
Txt%5C00000001%5C30000909.txt&User=ANONYMOUS&Password=anonymous&SortMeth
od=h%7C-
& M ax i m uni Docum ent s= 1 &FuzzyDegree=0&ImageOualitv=r7 5 g8/r7 5 g8/x 150yl50gl 6/i425&D
isplav=p%7Cf&DefSeekPage=x&SearchBack=ZvActionL&Back=ZyActionS&BackDesc=Resu
1 ts%20page& M axi mum Pages=1 &ZyEntry= 1 & SeekPage=x&ZyPURL
U.S. EPA-b (U.S. Environmental Protection Agency). 1979. Estimating water treatment costs:
volume 2 - cost curves applicable to 1 to 200 mgd treatment plants. EPA-600/2-79-162b. 1979.
http://vosemite.epa.gOv/vvater/ovvrccatalog.nsf/9da204a4b4406ef885256ae0007a79c7/b772717b
690a5b 1 a85256b0600723 835! Open Docum ent
U.S. EPA-c (U.S. Environmental Protection Agency). 1979. Estimating water treatment costs,
volume 3 - cost curves applicable to 2,500 GPD to 1 mgd treatment plants, summary. 1979.
EPA-600/2-79-162c. 1979.
http://nepis.epa.gov/Exe/ZyNET.exe/3000091H.TXT?ZyActionD=ZyDocument&Client=EPA&l
ndex= 1976+Thru+1980&Docs=&Ouerv=&Time=&EndTime=&SearchMethod= 1 &TocRestrict
=n&Toc=&TocEntrv=&OField=&OFieldYear=&OFieldMonth=&OFieldDav=&lntOFieldOp=0
&ExtOFieldOp=0&XmlQuerv=&File=D%3A%5Czvfiles%5CIndex%20Data%5C76thru80%5C
Txt%5C00000001%5C300009IH.txt&User=ANONYMOUS&Password=anonvmous&SortMeth
od=h%7C-
& M ax i m um Docum ent s= 1 &FuzzyDegree=0&lmageQualitv=r7 5 g8/r7 5 g8/x 150y 150g 16/i425&D
isplav=p%7Cf&DefSeekPage=x&SearchBack=ZvActionL&Back=ZyActionS&BackDesc=Resu
1 ts° o20page& M axi mum Pages=1 &ZyEntry= 1 &SeekPage=x&ZyPURL
Wines, M. 2016. Oklahoma puts limits on oil and gas wells to fight quakes. New York Times,
March 7, 2016. Available at http://www.nytimes.eom/2016/03/08/us/oklahoma-earthciuakes-oil-
gas-vvel 1 s.htm 1'?rref=col 1 ection& r=0.
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3.7. Chemicals Used or Present in Hydraulic Fracturing Fluids
Question 7: The assessment used available information and data to identify chemicals used in hydraulic
fracturing fluids and/or present in flow back and produced waters. Known physicochemical and
toxicological properties of those chemicals were compiled and summarized. This is addressed in
Chapter 9.
a. Does the assessment present a clear and accurate characterization of the available chemical
and toxicological information concerning chemicals used in hydraulic fracturing?
b. Does the assessment clearly identify and describe the constituents of concern that potentially
impact drinking water resources?
c. Are the major findings fully supported by the information and data presented in the
assessment? Are there other major findings that have not been brought forward? Are the
factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
d. Are the uncertainties, assumptions, and limitations concerning chemical and toxicological
properties fully and clearly described?
e. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize chemical and toxicological information in this
assessment? Are there relevant literature or data sources that should be added in this section
of the report?
Chapter 9 presents a discussion on the identification and hazard evaluation of constituents used and
encountered across the HFWC. The chapter describes constituents used in hydraulic fracturing fluids,
constituents detected in flowback and produced water, toxicological and physicochemical properties of
hydraulic fracturing constituents, the selection of toxicity values including reference values and oral
slope factors, and physicochemical properties of such constituents, and provides a summary of
additional sources of toxicity information. The chapter presents a discussion on hazard identification of
reported hydraulic fracturing constituents, including how constituents were selected for hazard
identification, a multi-criteria decision analysis framework for hazard evaluation, and a summary of
constituents detected in multiple stages of the HFWC. The chapter concludes with a synthesis of major
findings, discussion of factors affecting the frequency or severity of impacts, and description of
uncertainties.
3.7.1. Summary of Available Information on Hydraulic Fracturing Chemicals
a. Does the assessment present a clear and accurate characterization of the available chemical and
toxicological information concerning chemicals used in hydraulic fracturing?
In the draft Assessment Report the EPA clearly articulates their approach for characterizing the available
chemical and toxicological information, including listing several sources for toxicological data in
Appendix G that did not meet their criteria. The assessment in Chapter 9 does a good job as a first
attempt to assess a very large and complex set of issues on a nationwide basis and introduce an approach
that integrates toxicology data with physicochemical properties.
The EPA developed a multi-criteria decision analysis (MCDA) approach to analyze hydraulic fracturing
constituents for those which may be of most concern. The SAB finds that inclusion of both exposure and
toxicity data are of paramount importance in such an approach. Physicochemical properties of
constituents (mobility in water, volatility, and persistence) were included as surrogates of exposure in
the approach developed by the EPA. A significant limitation of the EPA's approach was that criteria for
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physicochemical data and toxicological data were applied inconsistently, which resulted in
underutilization of much relevant available information and did not recommend inclusion of exposure or
concentration data when available.
The toxicological information was not characterized in Chapter 9 of the draft Assessment Report in an
"inclusive" manner because the criteria applied for data acceptability were too restrictive (discussed in
greater detail under Charge Question 7c). While the SAB agrees with the EPA's inclusion of several
important sources for reference values listed in Section 9.3.1 and Appendix G (e.g., IRIS,3 HHBP,4
PPRTVs5), Agency for Toxic Substances and Disease Registry (ATSDR) Minimal Risk Levels
(MRLs),6 California EPA Toxicity Criteria Database, IPCS CICAD,7 IARC,8 NTP RoC9), the SAB does
not agree that the EPA should limit toxicological information to reference values (RfV) or oral slope
factors (OSFs) that were peer reviewed only by a governmental or intergovernmental source. By doing
so, the EPA ignored available toxicology data that may be acceptable for risk assessment, including
sources listed in Appendix G. 1.2 that the EPA excluded. Thus, the EPA's estimate that toxicity data
were unavailable for 87% of the 1,173 constituents is an overstatement of the scope of the problem.
At a minimum, the EPA should explicitly indicate what fraction of the identified constituents have
hazard/toxicity information if reliable sources from states, other federal agencies, and international
bodies would be employed, even if those sources do not meet the very stringent criteria used for MCDA
analysis. It would be very useful for stakeholders to have this information and references available. As
part of this effort, the EPA should reference and discuss the Organisation for Economic Co-operation
and Development (OECD) (2014) hydraulic fracturing scoping project which identified 1121 "unique"
hydraulic fracturing constituents based on input from OECD member countries including the United
States. The SAB reviewed the OECD summary document but did not have access to the databases and
spreadsheets that were referenced. The SAB agrees with the broader inclusion of toxicological data
outlined in the OECD summary. This OECD project concluded that "a large majority of substances
were likely to have data available that would allow basic hazard assessment" based on an initial survey
of the EU REACH registration database, the EU classification and labelling inventory, and titles of
citations in the literature (OECD 2014).
The EPA also briefly described the ACToR10 database as another potential source of toxicological
information in Section 9.3.4.2 of the draft Assessment Report, but did not include this dataset in the
MCDA approach or Appendix A-2 listing of toxicological information. The EPA reported that taking all
assays related to oral toxicity together, ACToR had data available on 1145 of the 1173 hydraulic
fracturing constituents, but only 55% of constituents had "relevant" oral toxicity data. The EPA should
clarify the definition of "relevant" and should broaden this definition to include short-term or chronic
oral toxicity studies considered acceptable for risk assessment purposes. The EPA should explicitly state
the total number of constituents for which in vivo toxicology data are available in ACToR, OECD, EU,
and other databases excluded by the EPA, and should incorporate this information into the MCDA
approach and add this information to Appendix A-2. As discussed in the SAB's response to Charge
Question 7e, in cases where no in vivo data are available, the EPA is encouraged to consider emerging
3 Integrated Risk Information System, U.S. Environmental Protection Agency
4 Human health benchmarks for pesticides, U.S. Environmental Protection Agency
5 Provisional peer-reviewed toxicity values, U.S. Environmental Protection Agency
6 ATSDR Minimum risk levels
7 International Programme on Chemical Safety Concise International Chemical Assessment Documents
international Agency for Research on Cancer
9 National Toxicology Program Report on Carcinogens, U.S. Department of Health and Human Services
i° Aggregated Computational Toxicology Resource, U.S. Environmental Protection Agency
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high-throughput computational approaches, which are included in the ToxCast database and also
searchable in the ACToR database.
The draft Assessment Report also fails to note or make clear that some of the identified constituents
without reported toxicity information are (a) food additives, dietary supplements or, by FDA criteria are
generally recognized as safe (GRAS) at specified levels with known human safety profiles
(http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/); or (b) are chemically related forms
of the same substance, for which it would be reasonable to attribute similar safety profiles within the
quartiles of toxicity used in the evaluation. In fact, the problem of availability of toxicological
information for many constituents is not unique to hydraulic fracturing, and the EPA should consider
developing a tiered approach for toxicological information, including read-across methods of grouping
constituents of similar structure (http://echa.europa.eu/support/grouping-of-substances-and-read-across)
[European Centre for Ecotoxicology and Toxicology of Chemicals (Ecetox) Technical Report 116],
A more important limitation of the EPA's hazard characterization is that very little attention is paid to
the initial problem formulation stage of risk assessment, as recommended by NAS (2008). This initial
problem formulation step should be used to identify the most likely potential hazards of greatest
concern, and then this should be used to guide what toxicological information is most relevant. Instead,
the EPA focuses exclusively on identifying formal noncancer oral reference values (RfVs) and cancer
oral slope factors (OSFs) for constituents, without providing sufficient rationale for frequency, duration,
or intensity of exposure. Potential hazards that were highlighted in previous chapters and are of public
concern were not addressed adequately in this chapter (e.g., flammability of methane gas in Chapter 6,
and possible disinfection by-products [DBPs] in Chapter 8). Furthermore, if the most likely exposures of
concern are findings in shorter-term exposures, then findings in shorter-term toxicology studies that are
available from or used by governmental or non-governmental international organizations for risk
assessment (e.g., OECD screening information dataset) could be just as relevant as chronic studies. The
ATSDR publishes acute, intermediate, and chronic ATSDR MRLs for many constituents. American
Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) and National
Research Council's acute exposure guideline levels (http://dels.nas.edu/global/best/AEGL-Reports)
pertain to inhalation exposures, which may be pertinent to some drinking water exposure scenarios. The
EPA should characterize toxicological information on constituents employed in hydraulic fracturing in
an inclusive manner, and not restrict the criteria for selection of hydraulic fracturing constituents of
concern to those that have formal noncancer oral reference values (RfVs) and cancer oral slope factors
(OSFs) for those constituents.
In contrast to the toxicological information, the EPA uses chemical databases that are not peer reviewed
for physicochemical parameters. The EPA uses the frequency of reporting in FracFocus, and Kow values
calculated from EPI Suite KowWIN software, to develop lists of constituents of interest (Section 9.4.1)
and characterize "exposure" (Section 9.5.2). The SAB agrees with the EPA's general approach to use
available data to estimate exposure for MCDA assessments. However, more rigorous discussion of the
limitations of these data is needed to estimate exposure in drinking water and thus, potential adverse
effects. Since the MCDA gives equal weight to information on physicochemical scores, occurrence and
toxicity, this may place undue emphasis on the physiochemical score. While it may be useful in judging
a constituent's likelihood of occurrence in drinking water, this value may be a relatively poor surrogate
for actual exposure. Constituents may not be addressed that tend to remain at their original deposition
site and serve as a reservoir for prolonged release. In light of these limitations, the agency should use
MCDA results for preliminary evaluation purposes only. The agency should use MCDA on a regional or
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site-specific basis where more complete constituent identity, concentrations and toxicity information is
available.
The SAB has concerns about the selection of specific factors in the examples. The EPA describes the
limitations of the voluntary FracFocus database, but does not adequately justify their selection of
frequency of occurrence, instead of the median maximum concentration in hydraulic fluid, to estimate
the likelihood of exposure. A constituent could be used frequently but at very low concentrations in
hydraulic fracturing fluids, and therefore be of little concern toxicologically. The EPA should also
acknowledge that very potent constituents can be present but maybe only at specific sites.
Considerations of these situations should also be included in the explicit problem formulations. The
EPA should also recognize the concerns regarding its reliance on the FracFocus version 1.0 data, and, if
possible, provide an initial characterization of differences in uses of HF constituents reported in
FracFocus 3 compared to FracFocus 1.0.
The SAB recommends that the EPA use experimental Kow values when available, and discuss the
reliability of the EPI Suite KowWIN software to estimate Kow for the structures and range of values
estimated. ACToR and REACH are potential sources of experimental Kow and other physicochemical
values that the EPA should use. In addition, the EPA should discuss the chemical information within the
context of the HFWC, to describe differences in constituent characteristics, such as mobility when the
constituent spills as a solvent (100% concentration), and after it is diluted to much lower concentrations
in hydraulic fracturing fluid, flowback, or produced water. The SAB encourages the EPA to more
broadly include available physicochemical data on constituents, which may be limited in that they only
provide suggestions on bioavailability, lipid solubility, and potential for exposure. Such data together
with toxicology data can be used to identify possible exposure boundaries that will allow policy makers
and users of the assessment to prioritize constituent exposures of greater concern.
3.7.2. HF Constituents of Concern
b. Does the assessment clearly identify and describe the constituents of concern that potentially impact
drinking water resources?
In the draft Assessment Report, EPA clearly identifies and describes 1,076 constituents historically used
in hydraulic fracturing fluids (Appendix A-2), and 134 constituents reported in flowback and produced
water (Appendix A-4). The EPA should be commended for being very clear and transparent in
Appendix A about the sources of information on which they relied for each constituent listed. These lists
provides a valuable starting point for further refinement and updates. The SAB encourages the EPA to
reconcile its lists of constituents with the international OECD (2014) list of constituents as a further
check of potential constituents of interest, although the SAB recognizes that there are differences in
regulations and practices between the European Union and the United States.
In addition, Chapter 9 of the draft Assessment Report notes that 70% of disclosures contain at least one
CBI constituent. In the final Assessment Report the SAB recommends that the EPA bring forward
information and approaches from Chapter 5 to clarify that 11% of all hydraulic fracturing constituents
were CBI and characterize the toxicological properties of CBI constituents that were provided to the
EPA by nine service companies (discussed further under the SAB response to Charge Question 7e).
The EPA indicates that there is a paucity of information on constituent identity and concentrations in
flowback and produced water, with only three references cited in Table A-4 of the draft Assessment
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Report. Previous chapters suggest numerous pathways for potential impacts to drinking water but do not
indicate which of them are most likely to lead to drinking water contamination. Absent such directional
information, it is not feasible to conclude which constituents—each differing in occurrence,
concentration, and volume during the various phases of hydraulic fracturing gas and oil extraction—are
of greatest concern. While additional field studies should be given a high priority to better understand
the intensity and duration of exposures to constituents of flowback and produced water (discussed
further under the SAB response to Charge Question 7e), such field studies can be considered a
recommendation for longer-term future activity.
In the absence of exposure information, the multi-criteria decision analysis (MCDA) approach presented
by the EPA is a commendable and reasonable conceptual approach to prioritize constituents of concern,
but not as the EPA prescribed it for a national level. The EPA clearly states that the approach is
described for illustrative purposes, to demonstrate how combining toxicological and physicochemical
information may be informative. The SAB supports an approach that considers both hazard and
exposure potential. However, due to the limitations described above and in the SAB's response to
Charge Question 7a, the EPA's MCDA results should be considered for preliminary hazard evaluation
purposes only, as the EPA originally intended. The MCDA approach presented can be useful on a
regional or site-specific basis when more adequate toxicological data (i.e., not based solely on RfD) and
constituent information (e.g., concentration and volume of spill) are available. In light of these
limitations, and given that the EPA applied this approach to only 37 constituents used in hydraulic
fracturing fluids and 23 constituents detected in flowback or produced water, the EPA should explicitly
state that these MCDA results should not be used to prioritize the constituents of most concern
nationally nor to identify future toxicity testing research needs.
EPA's MCDA results give equal weight to physicochemical score (water solubility, volatility, and
persistence in water) as to occurrence (concentration) and toxicity. The SAB is concerned that this may
place undue emphasis on the physicochemical scores, which may be a relatively poor surrogate for
exposure. While the SAB agrees that the three physicochemical sub-factors (water solubility, volatility,
persistence) are useful to judge the constituent's likelihood of higher concentrations in drinking water,
this approach may not adequately address constituents that tend to remain at their original site of
deposition and serve as potential reservoirs for sustained/prolonged low level release into drinking
water. The EPA discussed this uncertainty in Section 9.6.3 (last paragraph on page 9-8) of the draft
Assessment Report. However, the EPA should clearly emphasize that local exposure data on
concentration and volume of spilled liquids should take priority over these physicochemical score
surrogate measures and/or consider different weights for the physicochemical scores compared to
concentration and toxicity data. In addition, structure activity databases and approaches may provide
additional information relevant for estimating physicochemical properties (references listed in the
SAB's response to Charge Question 7e).
3.7.3. Major Findings
cl. Are the major findings fully supported by the information and data presented in the assessment?
The SAB has concerns regarding three of the major findings included in Chapter 9, as follows.
1. The EPA concludes, "Agencies may use these [MCDAJ results to prioritize chemicals for hazard
assessment or for determining future research priorities" (page 9-39 of the draft Assessment
Report). The SAB disagrees with this finding, based on the current method and limited scope of
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the MCDA exercise. The incomplete characterization of the available toxicological information
in Chapter 9 could misdirect policy makers to close inaccurately perceived hazard information
gaps. The lack of clarity or exclusion of such information inflates the "unknown" hazard
information, rather than making clear that there is a substantial body of unused hazard
information. The EPA should broaden the definition of relevant hazard information to include,
for example, toxicity data available from or used by the U.S. federal government, state
governments, or international non-governmental organizations used for risk assessment
purposes, or publicly available peer-reviewed data. The final Assessment Report should
explicitly indicate what fraction of the constituents identified in hydraulic fracturing fluid and/or
produced waters have some hazard information (e.g., toxicity data available from or used by the
U.S. federal government, state governments, or international non-governmental organizations for
risk assessment purposes, or publicly available peer-reviewed data), and what fraction have no
available information. The EPA should also provide information on toxicological properties of
CBI constituents based on the voluntary disclosures to the EPA and updated information
provided in the recent versions of FracFocus.
2. The EPA describes a list of potential hazards associated with constituents in multiple places in
Chapter 9 of the draft Assessment Report: "Potential hazards associated with these chemicals
include carcinogenesis, immune system effects, changes in body weight, changes in blood
chemistry, cardiotoxicity, neurotoxicity, liver and kidney toxicity, and reproductive and
developmental toxicity. " In its present form, this statement does not take into account factors that
affect the frequency, duration, or severity of exposure. This major finding should be qualified
with "depending on the level and duration of exposure" at the end of each of these sentences
throughout Chapter 9 and other parts of the document. In addition, the EPA should include in
Chapter 9 the paragraph found in the Executive Summary and Synthesis Chapters 10-8 line 13-
20, which clarifies that hazards, and thus impact on water quality, depend on magnitude of
exposure, and that this is best evaluated in site-specific assessments at the regional, local, or
individual water-tap levels.
3. The EPA's major conclusion is that there is a significant data gap with regard to hazard
identification, making it challenging to understand the toxicity and potential health impacts of
the large majority of constituents. As discussed in the SAB's response to Charge Question 7a,
this conclusion is not fully supported because the EPA did not use all reasonably qualified
toxicological information and approaches (e.g., did not use all United States and European Union
government- or international non-governmental organization-based toxicity data and safety
assessments, nor accepted read-across approaches for highly similar constituents).
c2. Are there other major findings that have not been brought forward?
In Chapter 9 of the final Assessment Report the EPA should summarize from previous chapters the
discussions of potential hazards from methane (physical hazard), bromide and/or chloride-related
disinfection by-products formed in drinking water, and organics in hydraulic fracturing wastewater.
Information about exposure levels when available and regulatory action levels should be included to
provide context for these constituents as well as the naturally occurring radioactive materials.
The EPA should use the full body of toxicological information, consistent with the agency's usual
approach in hazard assessment. A criterion for acceptable toxicology data should be scientific and
regulatory guideline quality, rather than funding source and formal assessments of chronic reference
doses (RfDs). The EPA should take full advantage of the available peer-reviewed hazard assessments
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that were excluded in Section G. 1.2 of the draft Assessment Report, as well as other sources of
toxicological information. The SAB lists these additional sources below in the response to Charge
Question 7e. At a minimum, the EPA should include all state and federal government hazard
assessments in its analysis. This is particularly appropriate, because the EPA concludes that hazards are
best assessed on a local level. The European Chemicals Agency Website for Registration, Evaluation
Authorization Restriction of Chemicals (REACH/ECHA) is a database for toxicology and
physicochemical data that may be useful for a large spectrum of constituents. The EPA excluded MCLs
because they are treatment based (page 9-6), but the EPA could consider MCLs or Maximum
Contaminant Level Goals (MCLGs) (which are not treatment based) when evaluating concern levels
using the proposed MCDA approach. As the EPA broadens inclusion of toxicological information to
populate missing toxicity data, the agency can develop an expanded version of the tiered hierarchy of
toxicity values described in Section 9.3.1. This allows the EPA to give higher priority to RfVs without
excluding other toxicological information that is useful for hazard and risk assessment purposes.
The problem of availability of toxicology data for constituents is not unique to hydraulic fracturing, so
the EPA might consider approaches used for toxicological data evaluation by the EPA and other
regulatory agencies, such as read-across and substances on the GRAS (U.S. FDA 1961) for some of the
substances (http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/).
The EPA should also directly consider and include exposure, use of threshold-of-toxicological-concern
(TTC) concepts, and use of best practices for mitigation of hazards identified in the course of the
analysis (e.g., recent information from FracFocus 3 and other sources on trends in substitution of less
hazardous constituents, as well as containment practices). These concepts and best practices should be
used to the extent feasible in the final Assessment Report or be explicitly noted as gaps in the
Assessment Report if not used. Since constituents that are highly diluted are less likely to produce toxic
effects, the SAB suggests the TTC be used to assign lower priority to contaminants potentially present in
these HF fluids. These assignments of lower priority should be based on calculated masses of
constituents used in HF considering the volume of dilution in various fluids (HF fluids, flowback, and
produced water) or based on measured concentrations. Constituents with calculated or measured
concentrations yielding daily intakes below the TTC could be eliminated as having potential impacts on
drinking water. This could focus any analyses to those constituents that have the potential to be present
at levels of concern.
3.7.4. Frequency or Severity of Impacts
c3. Are the factors affecting the frequency or severity of any impacts described to the extent possible and
fully supported?
There appears to be minimal emphasis on and discussion of factors that influence the frequency or
severity of potential impacts. For example, while there is some information on hydraulic fracturing
fluids used in various volumes and storage containers, as well as some mention of variations in
secondary containment, there is no discussion of how these factors could influence spill conditions,
aside from noting container failure as a substantial contribution to spills. Likewise, while there is
discussion of well failures as a potential impact on drinking water resources, there is limited discussion
of the likelihood of failure at different production stages (e.g., well communication failures,
overpressuring failures, and structural failures during operation) and the type of constituents that would
be released. Each of these elements (and numerous others) is discussed in the draft Assessment Report,
but there is limited synthesis of how this may affect the severity of impacts on drinking water resources.
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3.7.5. Uncertainties, Assumptions and Limitations
d. Are the uncertainties, assumptions, and limitations concerning chemical and toxicologicalproperties
fully and clearly described?
The EPA clearly states in Chapter 9 what they report as uncertainties, assumptions, and limitations.
However, the SAB notes areas of disagreement with some of the assumptions, limitations, and
uncertainties presented.
A major assumption was that chronic toxicity data should be the basis for identifying constituents of
potential concern. It is not likely, based on the nature of the exposures (for example, local surface spills),
that all exposures or impacts will be chronic. Data provided in some of the cases where measurements
were made point to transient, rather than chronic, exposure durations. This assumption, while perhaps a
useful simplification, should be explicitly indicated as resulting in some data gaps and overestimates of
the severity of some impacts (e.g., those noted to yield transient exposures).
A major uncertainty is whether the list of constituents used for hydraulic fracturing (Table A-2), based
on references listed in Table A-l of the draft Assessment Report, is representative of current hydraulic
fracturing practices. This could be better characterized by comparing constituents listed in FracFocus
versionl.O with those in FracFocus 3 to help assess whether the hydraulic fracturing industry is changing
constituents used within the HFWC, and whether there is movement in the United States toward
"greener" chemistry. While this use of the FracFocus database may provide useful information, the SAB
expresses concern that the FracFocus database may not be sufficient because it does not include certain
CBI information which is proprietary, and lacks information on the identity, properties, and frequency of
use for approximately 11% of hydraulic fracturing constituents used in HF operations (which are
considered CBI; see EPA draft Assessment Report, p. 5-73). The agency should acknowledge the
limitations on information about what is being injected, and should describe these concerns regarding its
reliance on FracFocus version 1.0 data within the final Assessment Report. Within the final Assessment
Report, the agency should also characterize data that the EPA may have on proprietary constituents, and
information provided in FracFocus on chemical class and concentration (i.e., concentration of the
constituent, in terms of % by mass, in the hydraulic fracturing fluid). In addition, the agency should note
that the current version of FracFocus may provide some additional insights into the CBI associated with
chemicals used during HF operations (for example, chemical type and categories).
3.7.6. Information, Background or Context to be Added
el. What additional information, background, or context should be added, or research gaps should be
assessed, to better characterize chemical and toxicological information in this assessment?
As discussed in the SAB's response to Question 7a, very little attention is paid to the initial problem
formulation stage of risk assessment, as recommended by the NAS (2008). The EPA should carry
forward to this chapter discussion of the most likely pathways for potential impacts to drinking water
resources based on consideration of case studies, retrospective studies, and/or scenarios for private well
and downstream surface water municipal water treatment plants that were discussed in previous
chapters. In doing so, the EPA should clearly distinguish between HFWC event versus severity of
impact in Chapter 9. For example, a temporary HFWC event could result in shorter-term or longer-term
impact, and an event limited in geographical scale could have long-term health impact depending on
local conditions and severity of impact.
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When discussing the most likely scenarios for spills or leaks through the HFWC, it would be useful to
provide background and context on best practices and existing federal, state and tribal regulations that
govern spills and leaks that could be employed to further mitigate potential for exposure. The SAB finds
that resumption of local case studies or initiation of the originally planned studies described in the
research Study Plan (EPA 2011) could provide better understanding of exposure to constituents based on
actual scenarios, provided that adequate baseline data exist. Such data could also be used to "validate"
the MCDA approach by comparing the MCDA results using actual exposure data with results based on
use of the physicochemical properties in the MCDA equations (i.e., occurrence and Kow). Two Panel
members do not find the lack of such case studies to be a limitation to the draft Assessment Report,
based on the perspective that investigations conducted by universities, consulting firms, and other
external stakeholders could be used in lieu of the agency conducting such studies.
Additional field studies should be given a high priority, to develop a much more comprehensive
chemical exposure database. It is acknowledged in several places in the draft Assessment Report that
chemical hazard evaluation should be most useful to conduct on a regional or site-specific basis. It is
essential to have more extensive and reliable information on the intensity and duration of exposures to
determine whether hydraulic fracturing activities in different locales pose health risks. Therefore, it is
important to bring forward and synthesize the key information from case studies, retrospective studies,
and/or scenarios for private well and downstream surface water municipal water treatment plants that
were discussed in previous chapters. The recommendations in this paragraph can be considered as
recommendations for longer-term future activity.
As discussed in the SAB's response to Charge Questions 7a and 7c, the EPA should use the full body of
toxicological information, consistent with the agency's usual approach for hazard evaluation. A criterion
for acceptable toxicology data should be scientific and regulatory guideline quality, rather than funding
source and formal assessments of chronic RfDs. The EPA should include all state and federal
government hazard assessments, as well as peer-reviewed hazard assessments (especially those
following the EPA's approach for peer review), and MCLs or MCLGs in its analysis. Shorter-term and
chronic toxicology studies that meet OECD and General Laboratory Practices (GLP) guidelines (e.g.,
OECD screening information dataset) are relevant hazard data that should be included even if a formal
chronic RfD has not been established. The EPA should reference and utilize the OECD (2014) initial
survey and spreadsheets that identify constituents used in hydraulic fracturing with potential hazard data
based on EU REACH, EU Classification and Labeling inventory, and publications. Similarly, the EPA
should utilize ACToR to search for relevant oral short-term and chronic studies. Potential hazards that
were highlighted in previous chapters and are of public concern should also be added to Chapter 9 (e.g.,
flammability of methane gas in Chapter 6, and potential disinfection by-products [DBPs] in drinking
water treatment plants in Chapter 8). In addition, the EPA should also directly consider and include
exposure, use of TTC concepts, and use of best practices for mitigation of hazards identified in the
course of the analysis. The SAB suggests the TTC be used to assign lower priority to contaminants
potentially present in these HF fluids.
There is a gap in knowledge of constituents that are designated as confidential business information
(CBI). The chemical and toxicological information for CBI constituents used in hydraulic fracturing
activities should be better characterized using data that the EPA may have and/or information provided
in FracFocus regarding chemical class and concentration (i.e., concentration of the constituent, in terms
of % by mass, in the hydraulic fracturing fluid). The EPA should indicate in Chapter 9 that 11% of all
ingredients reported in FracFocus were CBI (page 5-73 line 28). The EPA can provide aggregate
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information on potential hazards posed by CBI constituents without publically disclosing specific
information. The EPA can characterize the toxicological and MCDA results in a manner similar to the
approach used for known constituents. This would enable an assessment of the potential for significant
impact (or not) from CBI constituents relative to known constituents. The EPA should also recognize the
concerns regarding its reliance on an early version of FracFocus data.
The EPA should distinguish between constituents injected into a hydraulic fracturing well vs.
constituents and hydrocarbons that come out of the well in produced fluids. The SAB suggests that if no
constituents are added to a hydraulic fracturing well, there is still a potential for impacts to drinking
water resources from constituents present naturally in the subsurface which could also be brought to the
surface in produced water. In Chapter 9 and throughout the final Assessment Report, constituents and
potential impacts unique to hydraulic fracturing oil and gas extraction should be clearly distinguished
from those that also exist as a component of conventional oil and gas development. This is not to say
that the ones that overlap both production methods should not be included, but rather that the ones that
may cause unique potential impacts from the specific methods of hydraulic fracturing production should
be highlighted. For example, it is not clear from this chapter of the draft Assessment Report to what
extent hydraulic fracturing produced water—through its constituents—poses significant, unique
potential impacts to drinking water resources (other than over the first few days when flowback water
contains hydraulic fracturing fluid constituents). As such, the agency should clarify whether constituents
identified as being of most concern in produced water are products of the hydraulic fracturing activity,
flowback, or later-stage produced water, or are constituents of concern derived from oil and gas
production activities that are not unique to hydraulic fracturing activity. This will help inform the
readers about the different characteristics of HF flowback and produced waters and in-situ subsurface
constituents relative to formation water produced in conventional oil and gas development. To
understand better the composition of these fluids, analytical methods may need to be developed, which
can be considered a recommendation for longer-term future research activity.
To help prioritize future research and risk assessment efforts, the agency should identify the most likely
exposure scenarios and hazards and obtain toxicity information relevant to those exposure scenarios.
The EPA provides a wide range of possible scenarios along the HFWC, but more emphasis is needed to
identify the most likely durations and routes of exposures of concern so that the EPA can determine
what toxicity information is most relevant and focus research and monitoring efforts on the most
important and/or likely scenarios. The SAB finds that the selection of likely scenarios should be based
on consideration of findings in prospective and retrospective site investigations, as well as case studies
of public and private wells and surface water supplies impacted by spills or discharges of flowback,
produced water or treated or partially treated wastewater from HFWC operations.
e2. Are there relevant literature or data sources that should be added in this section of the report?
As stated in the SAB's response to Charge Question 7a, the SAB supports use of the sources of
toxicological information that the EPA included. However, several additional sources were excluded or
not mentioned by the EPA and should be included; these are listed below. Many of these sources of
relevant in vivo toxicology data were mentioned in the SAB's response to previous the EPA Charge
Questions 7a-d. In addition, while the draft Assessment Report briefly described the ACToR database in
Chapter 9, the agency should fully utilize the in vivo toxicology and physicochemical data available
through ACToR, including acute, short-term, and chronic toxicity data, data on corrosivity, and
experimental physicochemical data. The physicochemical data (e.g., Kow) are not only useful for
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predicting toxicant fate and transport in drinking water resources, but also can contribute toward
evaluating the ability of a compound to cross cell membranes, which is relevant for predicting toxicity.
When no in vivo data are available, the EPA is encouraged to consider emerging high-throughput
screening approaches that also incorporate estimates of external doses (Wambaugh et al. 2013; Wetmore
et al. 2015). This approach is an advancement in the use of high-throughput screening data to prioritize
the use of oil spill dispersants (Judson et al. 2010). Despite limitations of the Judson et al. (2010)
approach, the publication illustrates a use of emerging approaches to address risk management needs
when in-vivo toxicology data are not available. The EPA should, as a longer-term future activity, review
the in vivo datasets and computational results available through ACToR and specifically state which
constituents have relevant in vivo data that can be used for risk assessment purposes despite not
achieving the EPA's strict inclusion criteria used in the draft Assessment Report. The SAB recommends
that the EPA also specify where emerging high-throughput test data are available within the ToxRef
database as a result of the EPA's computational toxicology research efforts.
Further, application of the Threshold of Toxicological Concern may be appropriate when evaluating the
potential impacts of highly diluted constituents (e.g., in flowback or produced water).
List of sources of in vivo toxicological information:
State RfV values: the EPA collected all publicly available RfVs and/or OSFs from different states,
including Texas, but they only included the California EPA values because they were peer-reviewed
according to the EPA's definition (Appendix G). The EPA should use all state values, especially
because the EPA encourages risk assessments at the local level. The EPA can choose to give lower
priority to state values that are not peer reviewed in their tiered hierarchical priority scheme, but should
not exclude these values as toxicological information.
• ACToR: the EPA discussed ACToR but did not include available in vivo toxicology data if they
did not meet the EPA's narrow definition of acceptable toxicological information. Thus,
toxicology studies reviewed by the EPA that are used to compare with high-throughput in silico
data were not included. The EPA should use the experimental physicochemical and in vivo
toxicology database available through ACToR. In addition, ACToR provides links to other
databases, including tools for using structure activity to predict toxicity.
• National Library of Medicine (NLM).The National Library of Medicine (NLM) has a
comprehensive website, the Toxicology and Environmental Health Information Program:
(TEH1P; https://www.nlm.nih.gov/pubs/factsheets/tehipfs.html). This website provides "one-stop
shopping" for toxicant information that is available free to the public. It provides resources from
the NLM and from other agencies/organizations. Included in this is the NLM's TOXNET
database, which has integrated all of the free toxicology and environmental health databases
available (see Appendix 1 for list). The SAB strongly encourages the EPA to discuss what
toxicity information is useful from this database. European Chemicals Agency Registration,
Evaluation Authorization Restriction of Chemicals (REACH) Information on Chemicals.
http://echa.europa.eu/information-on-chemicals. Includes physicochemical and toxicological data
for chemicals registered under REACH. As of September 2015 it provided data for 13441 unique
substances and contains information from 51920 Dossiers.
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U.S. FDA Generally Recognized as Safe (GRAS)
http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS. List of chemicals found in food
that are considered by FDA as generally recognized as safe either through scientific procedures
or, for a substance used in food before 1958, through experience based on common use in food.
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values
(TLV's). http://www.acgih.org/tlv-bei-guidelines/policies-procedures-presentations/overview.
The EPA excluded these assessments because they are specific to workers and not generalizable
to the general public and because it is not a governmental or intergovernmental body. Rather
than ignore these values completely, the EPA should consider these assessments as valuable
sources of peer reviewed toxicological values that can be adapted for drinking water risk
assessment needs when other RfVs are unavailable.
Organisation for Economic Co-operation and Development (OECD). 2014. Provision of
knowledge and information - chemicals used in hydraulic fracturing. 52nd Joint Meeting of the
Chemicals Committee and the Working Part on Chemicals, Pesticides and Biotechnology.
ENV/JM(2014)25. For presentation at November 4-6, 2014 Meeting, Paris, France. September
19, 2014. The report provides data to support their conclusion that a large majority of substances
used in hydraulic fracturing are likely to have data available that would allow basic hazard
assessment. This report includes "factsheets" for each responding country including the U.S., one
spreadsheet that identifies chemicals and elucidates hazard data availability and a second that
contains (limited) information on commercial products in which chemicals were found,
concentrations of chemicals in commercial products, typical concentrations of constituents and
product in hydraulic fracturing fluids.
Toxicology Excellence for Risk Assessment International Toxicity Estimates for Risk
Assessment http://www.tera. org/iter/. ITER (International Toxicity Estimates of Risk) is a free
Internet database of human health risk values for over 680 constituents of environmental concern
from several government organizations worldwide (e.g., ATSDR, Health Canada, U.S. The EPA,
RIVM.)
Toxicology Excellence for Risk Assessment Voluntary Children's Chemical Evaluation Program
Peer Consultations, http://www.tera.org/Peer/VCCEP/index.htm 1. The VCCEP pilot program
uses a tiered testing approach to assessing need of data for risk assessment purposes. For toxicity
data, specific types of studies have been assigned to one of three tiers. For exposure data, the
depth of exposure information increases with each tier. These data and the proposes risk
assessments are reviewed based on procedures in accordance with the U.S. Office of
Management and Budget, the National Academy of Sciences, and the U.S. The EPA.
European Chemicals Agency Grouping of substances and read-across
http://echa.europa.eu/support/grouping-of-substances-and-read-across. Provides general
guidance and examples of how to group substances based on the read-across approach.
European Centre for Ecotoxicology and Toxicology of Chemicals (2012). Category approaches,
Read-across, (Q)SAR. Technical Report 116). Provides state-of-the art practical read-across
strategies in applying non-testing approaches for regulatory purposes.
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Additional relevant literature:
The SAB recommends that the EPA consider the following additional literature sources within this
chapter of the final Assessment Report:
• Elliot, Elise G., A.S. Ettinger, B.P. Leaderer, M.B. Bracken, and N.C. Deziel. A systematic
evaluation of chemicals in hydraulic-fracturing fluids and wastewater for reproductive and
developmental toxicity. 2016. Jrnl. of Exp. Sci. andEnv. Epi. Advance online publication, 6
January 2016; doi:10.1038/jes.2015.81." Note: this reference has been added for the EPA's
consideration since it shows the use of chemical/physical factors in reviewing HF constituents.
• Judson, R.S., Martin, M.T., Reif, D.M., Houck, K.A., Knudsen, T.B., Rotroff, D.M., Xia, M.,
Sakamuru, S„ Huang, R., Shinn, P., Austin, C.P., Kavlock, R.J. and Dix, D.J. 2010. Analysis of
eight oil spill dispersants using rapid, in vitro tests for endocrine and other biological activity.
Environ Sci & Technol. 44, p. 5979-5985.
• National Academies Press. 2008. Science and Decisions: Advancing Risk Assessment. ISBN:0-
309-12047-0; http://www.nap.edu/catalog/12209.html.
• Organisation for Economic Co-operation and Development (OECD). 2014. Provision of
knowledge and information - chemicals used in hydraulic fracturing. 52nd Joint Meeting of the
Chemicals Committee and the Working Part on Chemicals, Pesticides and Biotechnology.
ENV/JM(2014)25. For presentation at November 4-6, 2014 Meeting, Paris, France. September
19, 2014.
• Wambaugh, J.F., R.W. Setzer, D.M. Reif, S. Gangwal, J. Mitchell-Blackwood, J.A. Arnot, O.
Joliet, A. Frame, J. Rabinowitz, T.B. Knudsen, R.S. Judson, P. Egeghy, D. Vallero, and E.A.
Cohen Hubal. 2013. High-throughput models for exposure-based chemical prioritization in the
ExpoCast Project. Environ Sci Technol 47(15), p. 8479-8488. August 6, 2013. doi:
10.1021/es400482g.
• Wetmore, B.A., J.F. Wambaugh, B. Allen, S.S. Ferguson, M.A. Sochaski, R.W. Setzer, K.A.
Houck, C.L. Strope, K. Cantwell, R.S. Judson, E. LeCluyse, H. Clewell, R.S. Thomas, and M.E.
Andersen. 2015. Incorporating high-throughput exposure predictions with dosimetry adjusted in
vitro bioactivity to inform chemical toxicity testing. Toxicol Sci. 148(1), p. 121-36. November
2015. doi: 10.1093/toxsci/kfvl71.
• APPENDIX 1 The National Library of Medicine (NLM) Toxicology and Environmental Health
Information Program (TEH1P) Fact Sheet, https://vvvvvv.nlm.nih.uov/pubs/factsheets/tehipfs.html
TEHIP maintains a comprehensive web site that provides access to resources produced by it and by
other government agencies and organizations. This web site includes links to databases, bibliographies,
tutorials, and other scientific and consumer-oriented resources. TEHIP also is responsible for the
Toxicology Data Network (TOXNET®), an integrated system of toxicology and environmental health
databases that are available free of charge on the web. TOXNET includes:
• HSDB® (Hazardous Substances Data Bank) provides data for over 5,000 hazardous chemicals.
HSDB has information on human exposure, industrial hygiene, emergency handling procedures,
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environmental fate, regulatory requirements, nanomaterials, and related areas. The information in
HSDB has been assessed by a Scientific Review Panel.
• TOXLINE® has references to the biomedical literature on biochemical, pharmacological,
physiological, and toxicological effects of drugs and other chemicals. It contains over 4 million
citations, almost all with abstracts and/or index terms and CAS Registry Numbers.
• ChemlDplus® provides access to the structure and nomenclature authority files used for the
identification of chemical substances cited in NLM databases. The database contains more than
400,000 chemical records, of which over 300,000 include chemical structures.
• IRIS (Integrated Risk Information System) contains data in support of human health risk
assessment, including hazard identification and dose-response assessments. It is compiled by the
Environmental Protection Agency (EPA) and contains descriptive and quantitative information
related to human cancer and non-cancer health effects that may result from exposure to
substances in the environment. IRIS data is reviewed by the EPA scientists and represents the
EPA consensus.
• ITER contains data in support of human health risk assessments. It is compiled by Toxicology
Excellence for Risk Assessment (TERA) and contains data from CDC/ATSDR. Health Canada.
RIVM. U.S. The EPA. I ARC. NSF International and independent parties offering peer-reviewed
risk values. ITER provides comparison charts of international risk assessment information and
explains differences in risk values derived by different organizations.
• TRI (Toxics Release Inventory) is a set of publicly available databases containing information on
releases of specific toxic chemicals and their management as waste, as reported annually by U.S.
industrial and federal facilities to the EPA. There is information on over 650 chemicals and
chemical categories. Pollution prevention data is also reported by each facility for each chemical.
• CCRIS (Chemical Carcinogenesis Research Information System) is a factual data bank
developed by the National Cancer Institute. It contains evaluated data and information, derived
from both short and long-term bioassays on over 9,000 chemicals. Studies relate to carcinogens,
mutagens, tumor promoters, carcinogens, metabolites and inhibitors of carcinogens.
• GENE-TOX provides genetic toxicology (mutagenicity) test data from expert peer review of
open scientific literature for more than 3,000 chemicals from the EPA.
• DART® (Developmental and Reproductive Toxicology) provides biomedical journals references
covering teratology and other aspects of developmental and reproductive toxicology.
• LactMed (Drugs and Lactation Database) is a database of drugs and other chemicals to which
breastfeeding mothers may be exposed. It includes information on the levels of such substances
in breast milk and infant blood, and the possible adverse effects in the nursing infant.
• CPDB (Carcinogenic Potency Database) reports analyses of animal cancer tests used in support
of cancer risk assessments for human. It was developed by the Carcinogenic Potency Project at
the University of California, Berkeley and the Lawrence Berkeley National Laboratory. It
includes 6,540 chronic, long-term animal cancer tests.
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• CTD (Comparative Toxicogenomics Database) contains manually curated data describing cross-
species chemical-gene/protein interactions and chemical- and gene-disease relationships. CTD
was developed at North Carolina State University (NCSU).
In addition to TOXNET, other toxicology and environmental health-related web resources available
from TEHTP include:
• ALTBIB® provides access to PubMed®/MEDLINE® citations relevant to alternatives to the use
of live vertebrates in biomedical research and testing. Many citations provide access to free full
text.
• Dietary Supplement Label Database (DSLD) is a joint project of the National Institutes of Health
(NIH) Office of Dietary Supplements (ODS) and the National Library of Medicine (NLM). The
DSLD contains the full label contents from a sample of dietary supplement products marketed in
the U.S.
• Drug Information Portal is a gateway to selected drug information from the U.S. National
Library of Medicine and other key U.S. government agencies. It includes information on more
than 48,000 drugs from the time they are entered into clinical trials (Clinicaltrials.gov) through
their entry in the U.S. market place.
• Haz-Map® is an occupational health database designed for health and safety professionals and
for consumers seeking information about the adverse effects of workplace exposures to chemical
and biological agents. The main links in Haz-Map are between chemicals and occupational
diseases. These links have been established using current scientific evidence.
• Household Products Database links over 13,000 consumer brands to health effects from Material
Safety Data Sheets (MSDS) provided by manufacturers and allows scientists and consumers to
research products based on chemical ingredients.
• LiverTox provides up-to-date, comprehensive and unbiased information about drug induced liver
injury caused by prescription and nonprescription drugs, herbals and dietary supplements. It is a
joint effort of the Liver Disease Research Branch of the National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK) and the Division of Specialized Information Services
of the National Library of Medicine (NLM).
• TOXMAP® is a web site from the National Library of Medicine (NLM) that uses maps of the
United States to show the amount and location of toxic chemicals released into the environment.
Data is derived from the EPA's Toxics Release Inventory (TRI), which provides information on
the releases of toxic chemicals into the environment as reported annually by industrial facilities
around the United States.
• ToxMystery is an interactive learning site helping children age 7 to 10 find clues about toxic
substances that can lurk in the home. ToxMystery provides a fun, game-like experience, while
teaching important lessons about potential environmental health hazards. ToxMystery is
available in English and Spanish.
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• Tox Town is an interactive guide to the connections between commonly encountered toxic
substances, the environment, and the public's health. Tox Town is available in English and
Spanish.
TEHIP is part of the Division of Specialized Information Services (SIS) which produces information
resources covering toxicology, environmental health, outreach to underserved and special populations,
HIV/AIDS, drugs and household products, and disaster/emergency preparedness and response.
3.8. Synthesis of Science on Potential Impacts of Hydraulic Fracturing on Drinking Water
Resources, and Executive Summary
Question 8: The Executive Summary and Chapter 10 provide a synthesis of the information in this
assessment. In particular, the Executive Summary was written for a broad audience.
a. Are the Executive Summary and Chapter 10 clearly written and logically organized?
b. Does the Executive Summary clearly, concisely, and accurately describe the major findings
of the assessment for a broad audience, consistent with the body of the report?
c. In Chapter 10, have interrelationships and major findings for the major stages of the HFWC
been adequately explored and identified? Are there other major findings that have not been
brought forward?
d. Are there sections in Chapter 10 that should be expanded? Or additional information added?
Chapter 10 provides a synthesis of the information in the draft Assessment Report. The chapter
describes the major findings for each of the five HFWC stages: (1) water acquisition for hydraulic
fracturing fluids; (2) chemical mixing to form fracturing fluids; (3) well injection of fracturing fluids; (4)
flowback and produced water; and (5) wastewater treatment and disposal. It discusses key data
limitations and uncertainties, including limitations in monitoring data and chemical information. It also
presents conclusions and uses for the draft Assessment Report. The Executive Summary provides a
similar synthesis of the information as provided in Chapter 10, and also includes a discussion of the
scope and approach of the draft Assessment Report and a description of the proximity of current
hydraulic fracturing activity and drinking water resources.
3.8.1. Organization of Executive Summary and Chapter 10
a. Are the Executive Summary and Chapter 10 [Synthesis] clearly written and logically organized?
The organization of the Executive Summary is logical, mirroring the draft Assessment Report's overall
structure that is framed around the identified stages of the HFWC. As currently written, the Executive
Summary is understandable to technical experts in geoscience and engineering, but will be less clear to a
general audience. This broader audience comprises a substantial portion of the Executive Summary's
readership and will include policy makers, regulators, the media, and the general public. The SAB
therefore recommends that the EPA should significantly modify the form and content of the Executive
Summary and Chapter 10 Synthesis of the final Assessment Report to make these discussions more
understandable to the reader and more suitable for a broad audience.
The SAB recommends that the EPA employ several strategies to facilitate the readership's
understanding of the Executive Summary and Chapter 10 Synthesis of the final Assessment Report. The
EPA should provide clearer statements on the goals and scope of the assessment and on specific
descriptions of hydraulic fracturing activities, and additional diagrams and illustrations should be
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provided to enhance the public's understanding of hydraulic fracturing activities and operations.
Technical terms should be clearly defined. Examples of these terms include, but are not limited to,
"chronic oral reference value," "slope factor," "well pad," "conductivity," and "integrity failure."
Measurements should, whenever possible, be placed in context to allow the reader to gain perspective.
For example, the text notes that approximately 4 million gallons is an average volume of water used
during hydraulic fracturing of a horizontal well. The text should note how this volume compares to
water consumed for other uses. As a second example, the draft Assessment Report describes wastewater
with radium activities exceeding tens of thousands of picocuries per liter. The final Assessment Report
should describe whether this is a dangerous level of radioactivity, and how these levels compare with
levels from other common radioactive sources.
Another way to facilitate understanding of the Executive Summary and Chapter 10 for a general
audience is to employ more figures, graphs, and text boxes. The EPA should include additional figures
to clarify key concepts. Since many readers will struggle to visualize a constructed gas well, the
heterogeneous nature of rocks and sediments that comprise drinking water aquifers and confining units,
and pathways by which surface spills may contaminate groundwater, soil water, and surface water,
diagrams and photographs would help in this regard. A map of the major shale plays in the United States
should also be considered for inclusion so that readers can visualize the geographic distribution of
unconventional oil-and-gas plays addressed in the Executive Summary.
The Executive Summary should cover the history of the EPA ORD effort surrounding the assessment of
hydraulic-fracturing impacts on drinking water. In particular, the Executive Summary should describe
the Research Scoping Plan, the development of the EPA's research Study Plan (U.S. EPA 2011), and the
EPA's 2012 Progress Report (U.S. EPA 2012). The peer review by the Science Advisory Board, as well
as efforts that the EPA undertook to engage stakeholders should also be summarized.
Prospective case studies, whereby drinking water resources at specific field sites were to be assessed
before and after hydraulic-fracturing activities, were part of the EPA's research Study Plan. These
planned prospective studies were not conducted or completed. While the reasons for not conducting
these studies were not described in the draft Assessment Report, the draft Assessment Report
acknowledges the lack of before-and-after studies as a serious limitation in the assessment of hydraulic
fracturing effects on drinking water. Since the EPA's exclusion of these studies could be construed as a
lack of due diligence on the part of the EPA without further explanation, the SAB finds that the EPA
should include in the Executive Summary its rationale for excluding the prospective case studies.
Further the SAB finds that the agency should highlight studies by other organizations that have
conducted work associated with a "prospective" view. Two Panel members do not find the lack of
prospective case studies to be a limitation to the draft Assessment Report, based on the perspective that
investigations conducted by universities, consulting firms, and other external stakeholders could be used
in lieu of the agency conducting such studies.
The Executive Summary focuses on national- and regional-level generalizations of the potential effects
of hydraulic fracturing-related activities on drinking water resources. Although these generalizations are
often desirable and useful, the EPA should make these conclusions cautiously, and clearly qualify these
conclusions through acknowledgement of the substantial heterogeneity existing in both natural and
engineered systems. Furthermore, the EPA should provide more emphasis in the Executive Summary on
the importance of local hydraulic fracturing impacts. These local-level impacts may occur infrequently,
but they have the potential to be severe and the Executive Summary should more clearly describe such
impacts. Data sources that suggest the possibility that hydraulic fracturing-related activities may have
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contaminated surface or groundwater at the local to sub-regional scale are provided in the response to
Charge Question 8(d) below.
The SAB finds that Chapter 10 - the Report Synthesis - is nearly identical to the Executive Summary.
The SAB concludes that this chapter should be rewritten. The EPA should revise the Synthesis to
integrate information and findings from the various chapters of the final Assessment Report.
Conclusions that are presented in the Synthesis should be more than results (e.g., measurements,
observations, and model calculations); they should describe what is learned from the analyses, results
and findings across the chapters and describe what these imply when considered together. In the present
version of the Synthesis, the Conclusions (Section 10.3) are presented on a single page, which is far too
cursory given the expansiveness of the draft Assessment Report's coverage. Moreover, the conclusions
are not illuminating: they reflect little in the way of new or original information and reveal only an
incremental advance in the knowledge of hydraulic fracturing impacts. The draft Assessment Report
contains a great deal of valuable information, yet the Synthesis does not carry that information forward,
fully describe and assess what the EPA learned from the assessment, nor describe the implications of
results that have been identified.
The SAB suggests that the EPA reorganize the Synthesis by prioritizing the major findings that have
been identified within Chapters 4-9 of the final Assessment Report (as opposed to mimicking the overall
organization of these chapters). The EPA should consider prioritizing these findings according to
expectations regarding the magnitude of the potential impacts of hydraulic fracturing-related activities
on drinking water resources. This structure could, in turn, facilitate consideration and explication of
particular practices that have mitigated, or could mitigate, the frequency and severity of water-resource
impairments that may be linked to the hydraulic fracturing-related activities.
3.8.2. Major Findings and Interrelationships of Major Hydraulic Fracturing Stages
b. Does the Executive Summary clearly, concisely, and accurately describe the major findings of the
assessment for a broad audience, consistent with the body of the report?
The Executive Summary does not clearly, concisely, and accurately describe the major findings of the
assessment for a broad audience. Some of the major findings are presented ambiguously within the
Executive Summary and appear inconsistent with the observations and data presented in the body of the
draft Assessment Report. The statements of findings in the Executive Summary should be linked clearly
to evidence provided in the body of the final Assessment Report and scrutinized to avoid any drift in
tone or in the way impacts are described or implied.
The SAB has concerns regarding the clarity and adequacy of support for several major findings
presented within the draft Assessment Report that seek to draw national-level conclusions regarding the
impacts of hydraulic fracturing on drinking water resources. The SAB is concerned that these major
findings do not clearly, concisely, and accurately describe the findings developed in the chapters of the
draft Assessment Report, and that the EPA has not adequately supported these major findings with data
or analysis from within the body of the draft Assessment Report. The SAB finds that these major
findings are presented ambiguously within the Executive Summary and appear inconsistent with the
observations, data, and levels of uncertainty presented and discussed in the body of the draft Assessment
Report.
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The SAB expresses particular concern regarding the draft Assessment Report's high-level conclusion
statement on page ES-6 that "We did not find evidence that these mechanisms have led to widespread,
systemic impacts on drinking water resources in the United States." The SAB finds that the EPA did not
support quantitatively its conclusion about lack of evidence for widespread, systemic impacts of
hydraulic fracturing on drinking water resources, and did not clearly describe the system(s) of interest
(e.g., groundwater, surface water), the scale of impacts (i.e., local or regional), nor the definitions of
"systemic" and "widespread". The SAB observes that the statement has been interpreted by readers and
members of the public in many different ways. The SAB concludes that if the EPA retains this
conclusion, the EPA should provide quantitative analysis that supports its conclusion that hydraulic
fracturing has not led to widespread, systemic impacts on drinking water resources. Most Panel
members also conclude that the statement requires clarification and additional explanation (e.g., discuss
what is meant by "any observed change" in the definition of "impact" in Appendix J, and consider
including possible modifying adjectives before the words "widespread, systemic impact" in the
statement on page ES-6). Four of the 30 Panel members find that this statement is acceptable as written,
but note that the EPA should have provided a more robust discussion on how the EPA reached this
conclusion (e.g., through a comparison of the number of wells drilled vs. reported spills, or analysis on
reported potable wells shown to be impacted by HFWC). Further details regarding these four Panel
member's opinion are noted in Appendix B to this Report.
Most members of the SAB Panel have concerns regarding the data limitations supporting the EPA's
major findings. These concerns include the nature of reported incidents of spilled liquids and releases
associated with hydraulic fracturing, the lack of systematic study of hydraulic fracturing-related impacts
that have occurred, the limited ability to review significant amounts of hydraulic fracturing data due to
litigation and confidential business information issues, and the lack of knowledge about or monitoring
methods for many constituents in hydraulic fracturing fluids.
Regarding the EPA's basis and support for its major finding regarding "widespread, systemic impact" in
the statement on page ES-6, the SAB Panel notes that the statement is presented also in Chapter 10 in
somewhat different form on pages 10-19 and 10-20, where it is stated that a major finding of the
assessment is a "lack of evidence that hydraulic fracturing processes have led to widespread, systemic
impacts on drinking water resources in the U.S. The number of identified cases appears to be small
compared to the number of hydraulically fractured wells. " While the draft Assessment reports that there
are insufficient data, a paucity of long-term systemic studies, and other mitigating factors, the SAB
concludes that the EPA has not gone far enough to emphasize how preliminary these key conclusions
are and how limited the factual bases are for these judgments.
Regarding the recommendation from most members of the SAB Panel that the EPA provide quantitative
support for its conclusion that hydraulic fracturing has not led to widespread, systemic impacts on
drinking water resources, the SAB notes that the EPA's estimates on the frequency of on-site spills were
based upon information from two states. While the SAB recognizes that the states of Pennsylvania and
Colorado likely have the most complete datasets on this topic that the EPA could access, the SAB
encourages the agency to contact state agencies, review state databases and update the draft Assessment
Report to reflect a broader analysis. While the SAB recognizes that state database systems vary, the
databases should be incorporated into the EPA's reporting of metrics within the final Assessment
Report. The SAB finds that the draft Assessment Report's analysis of spill data cannot be extrapolated
across the entire United States. The SAB recommends that the agency revisit a broader grouping of
states and "refresh" the final Assessment Report with updated information on the reporting of spills
associated with HFWC activities.
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In addition, the SAB finds that available data on the presence/identity of constituents in flowback and
produced water appears to be very limited. For example, only three references are cited for all of the
constituents listed in Table A-4 of the draft Assessment Report. Since information could not be located
on measured concentrations for many hydraulic fracturing constituents, it is not possible to estimate
human exposures or begin to assess the potential risks to health associated with exposures to these
constituents. The EPA should have some information, at least in terms of orders of magnitude, on how
exposures to certain hydraulic fracturing constituents compare to adverse effect doses for these
constituents (e.g., for a few of the most potent constituents) to make this major finding. The statement is
ambiguous and requires clarification and additional explanation.
Other examples of insufficient precision or elaboration on major findings within the Executive Summary
include:
• Page ES-6, lines 20-21: "The number of identified cases, however, was small compared to the
number of hydraulically fractured wells'' The descriptor "small" is vague and subjective. The
agency should quantify this statement based on the available data, and acknowledge the
uncertainty in the estimates. In addition, the agency should consider including other additional
benchmarks for comparison.
• Page ES-9, lines 19-20: "High fracturing water use or consumption alone does not necessarily
result in impacts to drinking water resourcesThis statement infers that to have an impact,
hydraulic fracturing activity must be the sole water use or source of consumption. While the
agency concluded they documented no case of stream impacts associated with the process of
hydraulic fracturing, there may be impacts associated with the HFWC or other activities that may
have occurred. The agency should revise this statement and discussion surrounding this
statement to reflect situations where hydraulic fracturing may have contributed to impacts that
have occurred, and to refer to cases described in Chapter 4 of the draft Assessment Report that
describe situations where hydraulic fracturing may have influenced streams that ran dry or
experienced very low flows and drinking water wells that ran out of water or experienced
significant declines in water level.
• Page ES-13, lines 22-23: "None of the spills of hydraulic fracturing fluid were reported to have
reached groundwater." This statement is not supported by the information and data presented in
the assessment, due to the EPA's incomplete assessment of spilled liquids and consequences. All
but one Panel member are concerned that this major finding is supported only by an absence of
evidence rather than by evidence of absence of impact.
• Page ES-15, lines 34-35: "According to the data examined, the overall frequency of occurrence
[of hydraulically fractured geologic units that also serve as a drinking water sources] appears to
be low. " The agency should clarify this ambiguous statement, including the use of the word
"low," and provide evidence within the assessment for this statement.
• Page ES-19, lines 18-19: "Chronic releases can and do occur from produced water stored in
unlinedpits or impoundments, and can have long-term impacts." The SAB notes that some states
(e.g., Ohio) do not require pit liners in hydraulic fracturing impoundments (Horner 2013). The
agency should discuss the frequency of this occurrence, provide details on pit liner requirements,
describe in what states reported releases occur most frequently (which presumably depends on
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reporting requirements), describe whether the frequency has decreased over time, and discuss the
impacts that may occur.
The SAB is concerned that the draft Assessment Report does not clearly, concisely, and accurately
describe these major findings for a broad audience, and that the EPA has not supported these six major
findings with data or analysis from within the body of the draft Assessment Report. The SAB concludes
that these major findings are presented ambiguously within the Executive Summary and appear
inconsistent with the observations and data presented in the body of the draft Assessment Report. Four
Panel members concluded that the major finding regarding "widespread, systemic impacts" is clear as
written. The SAB recommends that the EPA revise these statements of findings in the Executive
Summary and elsewhere in the final Assessment Report to clearly link these statements to evidence
provided in the body of the final Assessment Report. The SAB also recommends that the EPA discuss
the significant data limitations and uncertainties associated with these major findings, as documented in
the body of the final Assessment Report, when presenting the major findings. Regarding the EPA's
findings of gaps and uncertainties in publicly available data that the EPA relied upon to develop
conclusions within the draft Assessment Report, the EPA should clarify and describe the different
databases that contain such data and the challenges of accessing them, and make recommendations on
how these databases could be improved to facilitate more efficient investigation of these databases.
cl. In Chapter 10 [Synthesis], have the interrelationships and major findings for the major stages of the
HFWC been adequately explored and identified.
Chapter 10 devotes little attention to the interrelationships among the major stages of the HFWC. Its
presentation of major findings is incomplete, owing to insufficient analyses and omission of information
that should have been taken into account within the draft Assessment Report.
The draft Assessment Report compartmentalizes the major stages of the HFWC into separate chapters.
This compartmentalization is preserved in the Synthesis. As a result, implications that stem from
integration of the major findings and potential issues that cut across chapters of the draft Assessment
Report go largely unexplored.
The Synthesis does not culminate with any sort of integrated assessment of the relative contributions of
hydraulic fracturing-related activities to the drinking water resource impairment or depletion. Such an
integrated assessment would be useful and thus the EPA should consider rewriting Chapter 10 to
describe the integrated assessment of these activities. The agency should strengthen the Executive
Summary and Chapter 10 Synthesis by linking the stated findings more directly to evidence presented in
the body of the final Assessment Report. The SAB recognizes there may be difficulties in conducting
such an integrated assessment given the limitations in the availability of monitoring and other types of
environmental data as described repeatedly throughout the draft Assessment Report.
SAB's response above to sub-question b for Charge Question 8 regarding the Executive Summary
describes SAB's concerns and recommendations regarding the presentation of major findings within
Chapter 10 (since the presentation of major findings within Chapter 10 replicates the presentation of
major findings within the Executive Summary). As described in that response, some of the major
findings are presented ambiguously within the Executive Summary and appear inconsistent with the
observations and data presented in the body of the draft Assessment Report. The statements of findings
in the Executive Summary should be linked clearly to evidence provided in the body of the final
Assessment Report and scrutinized to avoid any drift in tone or in the way impacts are described or
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implied. Additional specific concerns and recommendations on this topic are provided in SAB's
response above to sub-question b for this charge question.
c.2 Are there other major findings that have not been brought forward?
The Synthesis (and the draft Assessment Report, more generally) fails to bring forward important
findings on the relationships between the HFWC and reported impacts to public and private wells and
surface water supplies including private wells in Dimock, Pennsylvania; Pavillion, Wyoming; and
Parker County, Texas. Although the role of hydraulic fracturing-related activities in water-well
contamination within these localities continues to be debated, these sites have a high profile and many
members of the public including other stakeholders view them as being of high potential relevance to
hydraulic fracturing-related impacts to drinking water resources. While the EPA appropriately aimed to
develop national-level analyses and perspective, many stresses to surface or groundwater resources
associated with stages of the HFWC are often localized in space and temporary in time, but nevertheless
can be important and significant. For example, many impacts of water acquisition will predominantly be
felt locally at small space and time scales. These local-level impacts, when they occur, have the potential
to be severe, and the final Assessment Report needs to better recognize the importance of local impacts.
In this context, the SAB recommends that the EPA should include and fully explain the status, data on
potential releases, and findings if available for the EPA and state investigations conducted in Dimock,
Pennsylvania; Pavillion, Wyoming; and Parker County, Texas where many members of the public have
stated that hydraulic fracturing activities have caused local impacts to drinking water resources.
Examination of these high-visibility, well-known cases is important so the reader can more fully
understand the status of investigations in these areas, conclusions associated with the investigations,
lessons learned, if any, for the different stages of the hydraulic fracturing water cycle, what additional
work should be done to improve the understanding of these sites and the HFWC, plans for remediation,
if any, and the degree to which information from these case studies can be extrapolated to other
locations.
3.8.3. Information, Background or Context to be Added
d. Are there sections in Chapter 10 [Synthesis] that should be expanded? Or additional information
added?
The Synthesis should be revised and expanded. As currently written, the Synthesis is a replication of
findings presented in the previous chapters. The Synthesis should be revised to be more integrative
according to SAB's response above to sub-questions a and c for Charge Question 8. Moreover, the
Synthesis should be expanded to present recommendations drawn from a holistic consideration of the
findings presented in Chapters 4-9 of the draft Assessment Report. These recommendations could
include discussion of current practices identified in the study that have been demonstrated to lower the
frequency of accidents (e.g., spills) and other problems (e.g., well-integrity failure) or improvements to
existing hydraulic fracturing practices.
While the Synthesis identifies several limitations and uncertainties that hinder evaluation of the potential
effects of hydraulic fracturing-related activities on drinking water resources, the Synthesis should
describe recommended next steps (e.g., where we go from here). The agency should revise Chapter 10 to
leverage the final Assessment Report's review of relevant literature and synthesis of knowledge gaps to
identify ongoing research, and data and research needs and steps that could reduce the uncertainties
associated with the potential effects of hydraulic fracturing-related activities on drinking water
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resources. This research agenda should be appropriately selective, perhaps consisting of one or two
priority research areas associated with each stage of the HFWC, as well as critical research foci that cut
across these stages.
The final Assessment Report should also identify future research and assessment needs and future field
studies. The SAB has identified a number of data and research needs in this report. Research needs
identified by other organizations who have studied potential impacts of unconventional oil and gas
development, e.g., the Health Effects Institute (HEI2015), should be examined in assembling the EPA
list of research needs. The SAB concludes that this discussion should include the EPA's plans for
conducting prospective studies and other research that the EPA had planned to conduct but did not
conduct. Two Panel members do not find the lack of prospective case studies to be a limitation to the
draft Assessment Report, based on the perspective that investigations conducted by universities,
consulting firms, and other external stakeholders could be used in lieu of the agency conducting such
studies. Given the length of time required to conduct prospective case studies and the need to finalize the
Assessment Report, the SAB recommends that the EPA consider the recommendations of all but two
Panel members to conduct research on expanded case studies and prospective case studies as an item for
longer-term future activity. This SAB Report also identifies several recommendations for future research
and assessment needs that should be considered for inclusion.
Data sources that suggest the possibility that hydraulic fracturing-related activities may have
contaminated surface or groundwater at the local to sub-regional scale:
Surface activities implicated in groundwater contamination:
• Drollette, B.D., K. Hoelzer, N R. Warner, T.H. Darrah, O. Karatum, M P. O'Connor, R.K.
Nelson, L.A. Fernandez, C.M. Reddy, A. Vengosh, R.B. Jackson, M. Eisner, and D.L. Plata.
2015. Elevated levels of diesel range organic compounds in groundwater near Marcellus gas
operations are derived from surface activities. Proceedings of the National Academy of Sciences
112(43), p. 13184-13189. October 27, 2015. doi/10.1073/pnas,1511474112.
Impacts to surface-water by inadequate treatment and disposal of HF-related wastewaters:
• Warner, N.R., C.A. Christie, R.B. Jackson, and A. Vengosh. 2013. Impacts of shale gas
wastewater disposal on water quality in western Pennsylvania. Environmental Science and
Technology. 47: 11849-11857.
• Olmstead, S.M., L.A. Muehlenbachs, J.S. Shih, Z. Chu, and A.J. Krupnick. 2013. Shale gas
development impacts on surface water quality in Pennsylvania. Proceedings of the National
Academy of Sciences 110: 4962-4967, doi: 10.1073/pnas. 1213871110.
Effects of gas-well drilling or improper zonal isolation on groundwater contamination.
• Llewellyn, G., F.L. Dorman, J.L. Westland, D. Yoxtheimer, P. Grieve, T. Sowers, E. Humston-
Flumer, and S.L. Brantley. 2015. Evaluating a groundwater supply contamination incident
attributed to Marcellus Shale gas development. Proceedings of the National Academy of
Sciences 112(20), 6325-6330. May 19, 2015. doi: 10.1073/pnas. 1420279112.
• Jackson, R.B., A. Vengosh, T.H. Darrah, N.R. Warner, A. Down, R.J. Poreda, S.G. Osborn, K.
Zhao, and J.D. Karr. 2013. Increased stray gas abundance in a subset of drinking water wells
near Marcellus shale gas extraction. Proceedings of the National Academy of Sciences. 110:
11250-11255.
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• Fontenot, B.E., L.R. Hunt, Z.L. Hildenbrand, D.D. Carlton Jr., H. Oka, J.L. Walton, D. Hopkins,
A. Osorio, B. Bjorndal, Q.H. Hu, and K.A. Schug. 2013. An evaluation of water quality in
private drinking water wells near natural gas extraction sites in the Barnett Shale Formation.
Environmental Science and Technology. 47: 10032-10040.
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REFERENCES
The following additional references were cited or included as suggested additional literature for the EPA
to consider within the body of the SAB Report, and are provided to improve the literature base for
EPA's final Assessment Report and to help ensure a more comprehensive understanding of hydraulic
fracturing activities and operations:
Abualfaraj, N., Gurian, P.L.; and Olson, M.S. 2014. Characterization of Marcellus Shale flowback
water .Environ. Eng. Sci. 31(9): 514-524. September 2014. doi:10.1089/ees.2014.0001.
Akob, D.M., I.M. Cozzarelli, D.S. Dunlap, E.L. Rowan, and M.M. Lorah. 2015. Organic and inorganic
composition and microbiology of produced waters from Pennsylvania shale gas wells. Applied
Geochemistry 60: 116-125. September 2015. doi:10.1016/j.apgeochem.2015.04.011.
Aly, M., B. Clancey, J. Montgomery, M. A. Bugti, A. F. Ahmadzamri. 2015. Geochemical Applications
for Identifying the Source of Hydrocarbons in Well Annuli. International Petroleum Technology
Conference. IPTC-18309-MS.
American Petroleum Institute (API). 2012. Overview of Industry Guidance/Best Practices on Hydraulic
Fracturing (HF). API. Available at
http://www.api.Org/~/media/Files/Policv/Exploration/Hydraulic Fracturing lnfoSheet.pdf.
Amy, G., M. Siddiqui, W. Zhai, J. DeBroux, and W. Odem. 1994. American Water Works Association
Research Foundation (AwwaRF) Final Report - Survey on bromide in drinking water and
impacts on DBP formation. American Water Works Association Research Foundation.
Amy, G., L. Tan, and M. Davis. 1991. The effects of ozonation and activated carbon adsorption on
trihalomethane speciation. Water Research 25(2): 191-202.
http ://www. sciencedirect.com/sci ence/arti cl e/pi i/0043 13549190029P
Archer, A.D. and P.C. Singer. 2006. An evaluation of the relationship between SUVA and NOM
coagulation using the ICR database. J. American Water Works Assn. 98(7): 110-123. July 2006.
Bachu, S. andR.L. Valencia. 2014. Well Integrity: Challenges and Risk Mitigation Measures. The
Bridge 44(2): 28-34.
Badruzzaman, M., J. Oppenheimer, S. Adham, and M. Kumar. 2009. Innovative beneficial reuse of
reverse osmosis concentrate using bipolar membrane electrodialysis and electrochlorination
processes. J. Membrane Sci. 326(2): 392-399. January 20, 2009.
Bair, E.S. and R.K. Digel. 1990. Subsurface transport of inorganic and organic solutes from
experimental spreading of oil-field brine. Ground Water Monitoring and Remediation 10(3): 94 -
105. August 1990.
Bair, E.S., D.C. Freeman, and J.M. Senko. 2010. Expert panel report on the Bainbridge Township gas
invasion incident. Ohio Department of Natural Resources, Division of Minerals Resources
Management, 2010, 431 p.
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APPENDIX A-EPA'S CHARGE QUESTIONS
Charge Questions for the SAB Review of the USEPA Report:
Assessment of the Potential Impacts of Hydraulic
Fracturing for Oil and Gas on Drinking Water Resources
Revised (October 8, 2015)
Background
The purpose of this assessment (U.S. EPA, 2015), entitled Assessment of the Potential Impacts of
Hydraulic Fracturing for Oil and Gas on Drinking Water Resources, was to synthesize available
scientific literature and data on the potential that hydraulic fracturing for oil and gas may change the
quality or quantity of drinking water resources, and to identify factors affecting the frequency or severity
of any potential changes. In fiscal year 2010, the U.S. Congress urged the U.S. Environmental
Protection Agency (EPA) to examine the relationship between hydraulic fracturing and drinking water.
In response, the EPA developed a research study plan (U.S. EPA, 2011) which was reviewed by the
Agency's Science Advisory Board (SAB) and issued in 2011. A progress report (U.S. EPA, 2012) on the
study detailing the EPA's research approaches and next steps was released in late 2012, and was
followed by a consultation with individual experts in May 2013. The EPA's study included original
research, and the results from these research projects were considered in the development of this draft
assessment report.
This assessment follows the HFWC described in the Study Plan and Progress Report. The water cycle
includes five stages: (1) water acquisition for hydraulic fracturing fluids; (2) chemical mixing to form
fracturing fluids; (3) well injection of fracturing fluids; (4) flowback and produced water; and (5)
wastewater treatment and disposal. Potential impacts on drinking water resources are considered at each
stage in this cycle. Drinking water resources are defined broadly within this report to include any body
of groundwater or surface water that now serves, or in the future could serve, as a source of drinking
water for public and private use.
EPA authors examined over 3,500 individual sources of information, and cited over 950 of these sources
for this assessment. Sources evaluated included articles published in science and engineering journals,
federal and state reports, non-governmental organization reports, oil and gas industry publications, other
publicly-available data and information, and data, including confidential and non-confidential business
information, submitted by industry to the EPA. The assessment also included citation of relevant
literature developed as part of the Study Plan.
This assessment is a synthesis of the science. It is not a human exposure or risk assessment, and does not
attempt to evaluate policies or make policy recommendations. Rather, it focuses on the potential impacts
of hydraulic fracturing activities, and factors affecting the frequency or severity of any potential
changes. As such, this report can be used by federal, tribal, state, and local officials; industry; and the
public to better understand and address vulnerabilities of drinking water resources to hydraulic
fracturing activities.
EPA asks the SAB to review the hydraulic fracturing drinking water assessment and provides the
following charge questions for that review. The charge questions follow the structure of the assessment.
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Charge question 1 asks about the introduction of the assessment (Chapter 1), and descriptions of
hydraulic fracturing activities and drinking water resources (Chapters 2-3). Charge questions 2 through 6
ask about the individual stages in the HFWC (Chapters 4-8). Charge question 7 asks about the
identification and hazard evaluation of chemicals (Chapter 9); and charge question 8 asks about the
synthesis of the material presented in the Executive Summary and Chapter 10.
Charge Questions
1. The goal of the assessment was to review, analyze, and synthesize available data and information
concerning the potential impacts of hydraulic fracturing on drinking water resources in the
United States, including identifying factors affecting the frequency or severity of any potential
impacts. In Chapter 1 of the assessment, are the goals, background, scope, approach, and
intended use of this assessment clearly articulated? In Chapters 2 and 3, are the descriptions of
hydraulic fracturing and drinking water resources clear and informative as background material?
Are there topics that should be added to Chapters 2 and 3 to provide needed background for the
assessment?
2. The scope of the assessment was defined by the HFWC, which includes a series of activities
involving water that support hydraulic fracturing. The first stage in the HFWC is water
acquisition: the withdrawal of ground or surface water needed for hydraulic fracturing fluids.
This is addressed in Chapter 4.
a. Does the assessment accurately and clearly summarize the available information
concerning the sources and quantities of water used in hydraulic fracturing?
b. Are the quantities of water used and consumed in hydraulic fracturing accurately
characterized with respect to total water use and consumption at appropriate temporal and
spatial scales?
c. Are the major findings concerning water acquisition fully supported by the information
and data presented in the assessment? Do these major findings identify the potential
impacts to drinking water resources due to this stage of the HFWC? Are there other
major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible and fully supported?
d. Are the uncertainties, assumptions, and limitations concerning water acquisition fully and
clearly described?
e. What additional information, background, or context should be added, or research gaps
should be assessed to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
3. The second stage in the HFWC is chemical mixing: the mixing of water, chemicals, and
proppant on the well pad to create the hydraulic fracturing fluid. This is addressed in Chapter 5.
a. Does the assessment accurately and clearly summarize the available information
concerning the composition, volume, and management of the chemicals used to create
hydraulic fracturing fluids?
b. Are the major findings concerning chemical mixing fully supported by the information
and data presented in the assessment? Do these major findings identify the potential
impacts to drinking water resources due to this stage of the HFWC? Are there other
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major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible and fully supported?
c. Are the uncertainties, assumptions, and limitations concerning chemical mixing fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
The third stage in the HFWC is well injection: the injection of hydraulic fracturing fluids into the
well to enhance oil and gas production from the geologic formation by creating new fractures
and dilating existing fractures. This is addressed in Chapter 6.
a. Does the assessment clearly and accurately summarize the available information
concerning well injection, including well construction and well integrity issues and the
movement of hydraulic fracturing fluids, and other materials in the subsurface?
b. Are the major findings concerning well injection fully supported by the information and
data presented in the assessment? Do these major findings identify the potential impacts
to drinking water resources due to this stage of the HFWC? Are there other major
findings that have not been brought forward? Are the factors affecting the frequency or
severity of any impacts described to the extent possible and fully supported?
c. Are the uncertainties, assumptions, and limitations concerning well injection fully and
clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
The fourth stage in the HFWC focuses on flowback and produced water: the return of injected
fluid and water produced from the formation to the surface and subsequent transport for reuse,
treatment, or disposal. This is addressed in Chapter 7.
a. Does the assessment clearly and accurately summarize the available information
concerning the composition, volume, and management of flowback and produced waters?
b. Are the major findings concerning flowback and produced water fully supported by the
information and data presented in the assessment? Do these major findings identify the
potential impacts to drinking water resources due to this stage of the HFWC? Are there
other major findings that have not been brought forward? Are the factors affecting the
frequency or severity of any impacts described to the extent possible and fully supported?
c. Are the uncertainties, assumptions, and limitations concerning flowback and produced
water fully and clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
The fifth stage in the HFWC focuses on wastewater treatment and waste disposal: the reuse,
treatment and release, or disposal of wastewater generated at the well pad. This is addressed in
Chapter 8.
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a. Does the assessment clearly and accurately summarize the available information
concerning hydraulic fracturing wastewater management, treatment, and disposal?
b. Are the major findings concerning wastewater treatment and disposal fully supported by
the information and data presented in the assessment? Do these major findings identify
the potential impacts to drinking water resources due to this stage of the HFWC? Are
there other major findings that have not been brought forward? Are the factors affecting
the frequency or severity of any impacts described to the extent possible and fully
supported?
c. Are the uncertainties, assumptions, and limitations concerning wastewater treatment and
waste disposal fully and clearly described?
d. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize any potential impacts to drinking water
resources from this stage of the HFWC? Are there relevant literature or data sources that
should be added in this section of the report?
7. The assessment used available information and data to identify chemicals used in hydraulic
fracturing fluids and/or present in flowback and produced waters. Known physicochemical and
toxicological properties of those chemicals were compiled and summarized. This is addressed in
Chapter 9.
a. Does the assessment present a clear and accurate characterization of the available
chemical and toxicological information concerning chemicals used in hydraulic
fracturing?
b. Does the assessment clearly identify and describe the constituents of concern that
potentially impact drinking water resources?
c. Are the major findings fully supported by the information and data presented in the
assessment? Are there other major findings that have not been brought forward? Are the
factors affecting the frequency or severity of any impacts described to the extent possible
and fully supported?
d. Are the uncertainties, assumptions, and limitations concerning chemical and toxicological
properties fully and clearly described?
e. What additional information, background, or context should be added, or research gaps
should be assessed, to better characterize chemical and toxicological information in this
assessment? Are there relevant literature or data sources that should be added in this
section of the report?
8. The Executive Summary and Chapter 10 provide a synthesis of the information in this
assessment. In particular, the Executive Summary was written for a broad audience.
a. Are the Executive Summary and Chapter 10 clearly written and logically organized?
b. Does the Executive Summary clearly, concisely, and accurately describe the major
findings of the assessment for a broad audience, consistent with the body of the report?
c. In Chapter 10, have interrelationships and major findings for the major stages of the
HFWC been adequately explored and identified? Are there other major findings that have
not been brought forward?
d. Are there sections in Chapter 10 that should be expanded? Or additional information
added?
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APPENDIX B-DISSENTING OPINION
Prepared by Stephen Almond, Shari Dunn-Norman, John Fontana, and Walt Hufford, Members
of the SAB Hydraulic Fracturing Research Advisory Panel
Preamble
In 2009, the U.S. House of Representatives Fiscal Year 2010 Appropriation Conference Committee
requested the United States Environmental Protection Agency (EPA or agency) conduct an assessment
on the potential impacts to drinking water from the process of hydraulic fracturing. In responding to that
request, EPA assigned to the Office of Research and Development (ORD) the task of developing and
executing an assessment that not only examined the process of hydraulic fracturing, but also greatly
expanded the scope to include the entire life cycle of oil and natural gas development associated with the
use, management and protection of water. The ORD held meetings with external stakeholders to gain an
understanding of the life cycle processes of exploration and production activities. Subsequently, ORD
developed a work plan detailing its proposed investigation of each of the principal areas the agency
identified as being relevant to the water life cycle, including: (1) sourcing of water, (2) mixing of water
with chemicals/proppant, (3) injection of water/proppant to fracture the reservoir, (4) management of the
flowback/produced water, and (5) reuse, treatment/discharge and disposal of these waters. Following the
development of a draft work plan in 2011, the agency initiated its investigation and has provided updates
regarding those efforts.
Early in the process, the EPA designated this effort as a Highly Influential Scientific Assessment (HISA).
Therefore, it is important that the SAB very carefully consider the wording and structure of our
responses to the EPA. Both the draft report issued by the agency in June 2015 and our work in the SAB
panel have been scrutinized by external stakeholders. As such, the facts and conclusions in our response
to EPA should be based on the body of scientific evidence that has been produced within the agency's
draft report and by other external stakeholders who have continued their work associated with life cycle
water use by the oil and natural gas industry. Significant effort has been expended by these external
stakeholders (academia, non-governmental organizations, other regulatory agencies and industry) to
both identify and mitigate risks dealing with hydraulic fracturing activities. This has included
investigations associated with water quality and quantity.
Following the release in June 2015 of the EPA draft report entitled Assessment of the Potential Impacts
of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources the SAB panel was asked to: 1)
respond to certain Charge Questions (CQs) that were submitted by the EPA, and 2) provide other
feedback associated with the draft report. Responses to these CQs have been developed through "face-
to-face" meetings, conference calls, and working group sessions that focused on each CQ. The SAB
panel heard from and reviewed comments (both oral and written) from the public as part of our
deliberations with over 396 unique comments provided to the SAB. This active participation included a
diverse group of individuals representing individual citizens, private property owners, environmental
organizations, trade associations and other entities.
This dissent is being provided while recognizing and respecting those on the panel who may disagree
with the opinions stated herein. Further, this document does not necessarily reflect the views or opinions
of any organization or affiliation and are offered as conclusions resulting from our deliberations. It is in
that spirit that these dissenting remarks and recommendations are offered.
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Dissenting Opinion
Major Finding of "no widespread, systemic impacts on drinking water resources
within the United States"
The first (January 7, 2016) draft of the SAB report provided the following text regarding this
conclusion:
The SAB has concerns regarding the clarity and adequacy of the support for several major
findings presented within the draft Assessment Report that seek to draw national-level
conclusions regarding the impacts of hydraulic fracturing on drinking water resources. The SAB
is concerned that these major findings are presented ambiguously within the Executive Summary
and are inconsistent with the observations, data, and levels of uncertainty presented and
discussed in the body of the draft Assessment Report. Of particular concern in this regard is the
high-level conclusion statement on page ES-6 that "We did not find evidence that hydraulic
fracturing mechanisms have led to widespread, systemic impacts on drinking water resources in
the United States. The SAB finds this statement does not clearly describe the system(s) of interest
(e.g., groundwater, surface water) nor the definitions of "systemic, " "widespread" or
"impacts. " The SAB is concerned that this statement does not reflect the uncertainties and data
limitations described in the body of the Report associated with such impacts. The statement is
ambiguous and requires clarification and additional explanation.
The SAB recommends that the EPA revise the major statements of findings in the Executive
Summary and elsewhere in the draft Assessment Report to be more precise, and to clearly link
these statements to evidence provided in the body of the draft Assessment Report.
The second (February 16, 2016) draft of the SAB report provides the following text regarding this
conclusion:
The SAB is concerned that these major findings as presented within the Executive Summary are
ambiguous and appear inconsistent with the observations, data, and levels of uncertainty
presented and discussed in the body of the draft Assessment Report. Of particular concern in this
regard is the high-level conclusion statement on page ES-6 that "We did not find evidence that
there mechanisms have led to widespread, systemic impacts on drinking water resources in the
United States". The SAB finds that this statement does not clearly describe the system(s) of
interest (e.g., groundwater, surface water) nor the definitions of "systemic, " "widespread". The
SAB agrees that the statement has been interpreted by member of the public in many different
ways and concludes that the statement requires clarification and additional explanation. "
The statement by the EPA in the draft Assessment Report issued in June, 2015 is clear, unambiguous,
concise, and does not need to be changed or modified. The statement provides a "holistic" conclusion of
the life cycle process of water used by the industry. While the report could have articulated the agency's
statistical assessment more clearly, there has not been any facts or evidence demonstrating a systemic or
widespread impact to existing drinking water resources or other water resources that may not meet the
current criteria of a drinking water resource. If a systemic or widespread issue had been identified, the
EPA and the state regulatory agencies would have quickly responded to such findings. In the absence of
such documented events, the conclusion is clear that no systemic, widespread impact to drinking water
resources is occurring. To suggest otherwise, undercuts the work and dedication by the employees of
those federal and state agencies who are charged with environmental protection. The draft EPA reports
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estimates approximately 30,000 wells are drilled each year in the United States. Only a very small
percentage of those wells have had an operational issue that may have impacted drinking water
resources. Even among this small percentage, the identified impacts to drinking water resources have
primarily been associated with surface spills, well construction, and well cementing - not hydraulic
fracturing.
The SAB panel is correct in highlighting that localized impacts should not be discounted nor
marginalized. Moreover, the SAB correctly identified that an aspect of the draft Assessment Report
dealing with the actual "impact" of a spill requires further clarification. A casual reader of the draft
report is left to question if impacts from all spills or releases are permanent or temporary. The agency
should expand the discussion around the actual timing of "impacts" to the local environment. In many
cases, including the ones referenced within the report, it is clear there is no long term demonstrated
impact associated with a release. The major conclusion by EPA in their June 2015 draft Assessment
Report stating "no widespread, systemic impacts on drinking water resources in the United States" is
accurate, unambiguous, and supportable with the facts EPA has reviewed.
Conclusion
This dissent to the SAB report focuses on the wording and conclusions of certain sections of that
document. With the designation of the USEPA assessment being classified as a Highly Influential
Scientific Assessment, the SAB report needs to clearly and concisely reflect the opinions of the SAB.
The structure provided by the agency and the SAB team provides an ability for panel members to
provide dissenting opinions, which will be used by the Chartered SAB and the EPA in finalization of
their final document.
This dissent describes that the conclusion by the EPA in the June 2015 draft Assessment report stating
"We did not find evidence that hydraulic fracturing mechanisms have led to widespread, systemic
impacts on drinking water resources in the United States" is accurate, clear, concise, unambiguous, and
supportable with the facts EPA has reviewed.
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