7/14/10

Opportunity for Stakeholder Input on
EPA's Hydraulic Fracturing Research Study:

Criteria for Selecting Case Studies

Hydraulic fracturing (HF) is a process used to increase the volume of natural gas that can be recovered from
sources such as coalbeds, tight sands, and shale formations. HF is also used for other applications like oil recovery.
During HF, fracturing fluids are injected into production wells under high pressure to generate fractures in geologic
formations. Fracturing fluids consist primarily of water and chemical additives that serve a variety of purposes,
such as increasing fluid viscosity, inhibiting corrosion, and limiting bacterial growth. Water used for HF activities
may come from surface water and ground water. Proppants (such as sand or ceramic beads) are added to keep the
fractures open after the pressure is released. The fracturing fluids (water and chemical additives) are then returned
back to the surface, where they are stored, treated, and disposed of or recycled. After fracturing, natural gas will
flow from pores and fractures in the rock into the well for subsequent extraction. Over the past few years, several
key technical, economic, and energy policy developments have increased the use of HF for gas extraction. HF is
now used more extensively and in a wider diversity of geographic regions and geologic formations. Along with
this expansion of HF, there have been increasing concerns about its potential impacts on drinking water resources,
public health, and the local environment.

EPA is developing a research study to examine the potential relationships between HF and drinking water. A key
goal of the EPA study is to generate data and information that can be used to assess risks and ultimately to inform
decisions. EPA has proposed four key approaches to obtain data and information to address research questions:

1.	Compile and analyze background data and information

2.	Characterize chemical constituents relevant to hydraulic fracturing

3.	Conduct case studies and computational modeling

4.	Identify and evaluate technological solutions for risk mitigation and decision support

The purpose of this document is to provide background information on the role of case studies in EPA's HF study
and to introduce a proposed process to identify, nominate, and select case studies. A critical step is to select and
prioritize sites for study. EPA is seeking stakeholder input on the proposed criteria for selecting case study
locations and appropriate research questions that may be answered using case studies.

Stakeholder Input

EPA requests input on the proposed criteria that may be used to determine case study locations. The Agency asks
that stakeholders consider the following questions:

•	Are the proposed selection and prioritization criteria appropriate?

•	Would you suggest revised or additional criteria to better identify, screen, and prioritize sites for field
investigations and case studies?

•	Are there other research questions that a case study approach would be uniquely able to address?

•	Are you aware of potential candidate sites or case studies that would be useful for this study? If so, what
are the characteristics that would make the candidates appropriate for this study on the relationship between
HF and drinking water resources? Please provide additional supporting information.

Stakeholders may submit comments to EPA on the proposed case study criteria by providing a verbal or written
comment during the public information meetings held during July and August 2010; emailing comments to
hydraulic.fracturing@epa.gov; or mailing written comments to Jill Dean, 1200 Pennsylvania Ave. NW, Mail code
4606M, Washington, DC 20460.

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7/14/10

Role of Case Studies in the HF Research Study

Case studies are widely used to conduct in-depth investigations of complex issues such as HF. The scope of case
studies can range from local or regional data collection and analysis at existing sites to extensive investigations on
new or planned HF sites, conducted in collaboration with industry or other partners. Developing a single national
perspective on HF is complex due to geographical variations in water resources, geologic formations, and
hydrology. In addition, the stressors on water resources vary over the lifecycle of hydraulic fracturing. Ideally, the
types of data and information that are collected through case studies should provide enough detail to determine the
extent to which conclusions can be generalized at local, regional, and national scales. Case studies, together with
other elements of the research program, can be used to help determine:

•	if drinking water resources are impacted by HF;

•	the extent and possible causes of any impacts; and

•	what can be done to avoid or mitigate impacts.

Conducting case studies can provide a forum for stakeholders to interact and exchange date and information. Case
studies may also provide data and model inputs on the fate and transport of fluids and contaminants that may vary
in different regions and geologic settings. In addition, case studies may inform the development of best
management practices for environmental protection.

The starting point for developing case studies is to define specific research questions that they can address. An
initial set of research questions proposed by EPA includes:

1.	What sampling strategies and analytical methods could be used to identify potential impacts on sources of
drinking water, water supply wells, and receiving streams?

2.	Are there vulnerable hydrogeologic settings where HF may impact the quality and availability of water
supplies?

3.	How does the proximity of HF to abandoned and/or poorly constructed wells, faults, and fractures alter
expected impacts on drinking water resources and human health?

4.	Is there evidence that pressurized methane or other gases, HF fluids, radionuclides, or other HF-associated
contaminants can migrate into underground sources of drinking water? Under what conditions do these
processes occur?

Data and Information Sought to Inform Design of Field Investigations and Case Studies

For candidate sites, efforts will be made to compile and review available data and identify gaps that need to be
addressed during initial site investigations. In addition, EPA may map and classify candidate sites based on
variations in geologic settings and infrastructure components to further prioritize the field investigations. Examples
of the types of data expected to be useful in characterizing candidate case studies include:

•	Depths of all existing well(s)

•	Well completion details (production and other nearby wells)

•	Well logs (production well and other nearby wells)

•	Cumulative production data

•	Cumulative injection data, including for stimulation

•	Data on the location, design, and operation of surface infrastructure, such as pits, evaporation ponds,
lagoons, etc.

•	Local geologic information including shallow ground water information

•	Ground water monitoring data

•	Cement bond logs

•	Geologic descriptions, cross sections

•	Modeling to estimate HF impacts (microseismic, water flow, chemical fate and transport, etc.)

•	Monitoring data (types of samples collected, parameters monitored, etc.)

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7/14/10

Potential Criteria for Case Studies

Case studies are likely to fall into the following categories: (a) sites where HF is being planned; (b) sites where HF
is in progress; or (c) sites where HF has already been completed. Because of the resource and time constraints
associated with EPA's study, it is only feasible to conduct a limited number of case studies. Therefore, criteria to
identify and select case studies are important, especially given the inherent complexities associated with the diverse
regional, geological, and community settings under which HF takes place.

The success of case studies depends on a clear definition of specific goals coupled with robust criteria for the
nomination and selection of cases. Some possible criteria for the selection of case studies include:

•	Proximity of other well penetrations

•	Proximity to drinking water resources

•	Geographic diversity

•	Potential to impact drinking water sources

•	Magnitude of activity (wells/acre)

•	Site history

•	Available data

•	Site access

•	Potential to collaborate with other stakeholders

A list of field-based activities relevant to key components of the HF lifecycle is shown along with potential site
selection criteria in Table 1.

Case Study Prioritization and Selection

EPA seeks advice from stakeholders regarding potential case studies. Stakeholders are invited to provide
suggestions and refinements to the prioritization of criteria and information listed in Table 1. Once candidates for
case studies are evaluated, EPA will select from among the candidates based on the extent to which the selected
case studies are expected to contribute answers to the high priority research questions. EPA will also consider
geographic and geologic diversity, potential availability of data and access, potential for effective collaboration, and
resources required.

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Table 1: Overview of field based HF activities, criteria and information needed for selecting case studies.

Hydraulic
fracturing
stage

Field activities to
determine potential
impacts on water resources

Potential criteria for selecting sites
for case studies

Information needed

Siting of

production

wells,

construction,
and well
development
and completion

Assess production well
integrity and monitor quality
and quantity of surface and
ground water supplies
before, during, and after
construction

Review of geology and
hydrology

Proximity of other well penetrations,
including drinking water supplies,
abandoned wells, other injection
activities

Proximity to drinking water
resources

Geographic diversity and population
density near site

Potential to leverage with other
partners (NGOs, industry, states,
etc.)

Well logs (geologic strata
descriptions), cement bond logs,
inventory of nearby wells, including
drinking water, production, disposal
and abandoned wells

Identification of local drinking water
supplies

Existing studies, investigations
Site access

HF of targeted

geologic

formation

Monitor on-site, up-gradient,
and down-gradient before,
during, and after HF

Microseismic monitoring

Potential for fluid migration beyond
HF zone and into underground
source(s) of drinking water

Potential for biogeochemical
mobilization of metals,
radionuclides, mineral salts, organic
contaminants and gases from gas-
bearing formations

Potential for surface water
withdrawals to affect drinking water
and/or impact flow regimes in
streams

Potential for ground water
withdrawals to affect water levels,
water quality, and the usability of
smaller aquifers for water supplies

Intensity and duration of HF activity
in a particular geographic location

Chemical baseline data for
production well, nearby drinking
water wells, other wells

Data on geologic and geochemical
characteristics of HF zone and
overlying zones

Historical data on nearby surface
water flows

Historical data on nearby water well
levels

Identification of current or possible
HF pads and /or leases in a particular
area

Management of
wastewater and
residuals

Monitor flowback water,
produced water, residuals,
storm water, receiving water,
wastewater treatment
facilities

Assess location practices,
operating characteristics,
capacity, and performance of
waste management activities

Potential for release to surface water Characteristics of wastewater

Potential for infiltration of
wastewater to underlying
underground source of drinking
water from pit storage water

Proximity of treatment facilities that
accept fracturing wastes

transport and storage systems

Relative location of waste water
treatment plants and /or underground
injection control (UIC) wells

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