United States Office of Water EPA 816-D-02-006
Environmental Protection (4606) August 2002
Agency
&EPA DRAFT Evaluation of Impacts to
Underground Sources of Drinking
Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
Executive Summary
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EPA 816-D-02-006
Executive Summary
This report summarizes findings from the US Environmental Protection Agency's (EPA)
hydraulic fracturing study. The goal of this first phase of the study was to determine if a threat
to public health as a result of underground sources of drinking water (USDW) contamination
from hydraulic fracturing of coalbed methane (CBM) wells (herein known as hydraulic fractur-
ing) exists, and if so, is it high enough to warrant further study. Based on the information col-
lected, the potential threats to USDWs posed by hydraulic fracturing of CBM wells appear to be
low and do not justify additional study.
This study is the most thorough effort conducted to review any impacts to public health as a result
of USDW contamination from hydraulic fracturing. If risks from hydraulic fracturing of CBM
wells were significant, we would expect to find instances of water well contamination from the
practice. Instead, thousands of CBM wells are fractured annually and yet EPA did not find persua-
sive evidence that any drinking water wells had been contaminated by CBM hydraulic fracturing.
EPA also evaluated the theoretical potential for hydraulic fracturing to impact drinking water
wells. In some cases, constituents of concern (see section ES-7) are injected into USDWs dur-
ing the course of normal fracturing operations. However, EPA's determination is that the threat
of contamination of drinking water supplies is low because concentrations are diminished by the
ground water production aspect of coalbed methane development. Studies have found no
observed breach of confining layers from hydraulically created fractures, consistent with theo-
retical understanding of fracturing behavior.
Although the threat to public health from hydraulic fracturing appears to be low, it may be feasi-
ble and prudent for industry to remove any threat whatsoever from injection of fluids. The use
of diesel fuel in fracturing fluids by some companies introduces the majority of constituents of
concern to USDWs. Water-based alternatives exist and from an environmental perspective,
these water-based products are preferable.
ES-1 How Does CBM Play a Role in the Nation's Energy Demands?
Coalbed methane mining began as a safety measure in underground coalmines to reduce the explo-
sion hazard posed by methane gas (Elder and Deul, 1974). In 1980, the U.S. Congress enacted a
tax credit for non-conventional fuels production, including coalbed methane production, as part of
the Crude Oil Windfall Profit Act. In 1984, there were fewer than 100 coalbed wells in the U.S.
By 1990, almost 8,000 coalbed wells had been drilled nationwide (Pashin and Hinkle, 1997). In
1996, coalbed methane production in 12 states totaled about 1,252 billion cubic feet, accounting for
approximately seven percent of U.S. gas production (U.S. Department of Energy, 1999). According
to the U.S. Department of Energy, natural gas demand is expected to increase at least 45% in the
next 20 years (U.S. Department of Energy, 1999). The rate of coalbed methane production is also
expected to increase in response to the growing demand.
DRAFT Evaluation of Impacts to Underground Sources August 2002
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs ES-1
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EPA 816-D-02-006
EPA reviewed geology in eleven basins, illustrated in Figure ES-1, throughout the U.S. The most
actively producing basins are highlighted in red on the map and include the Powder River Basin in
Wyoming and Montana, the San Juan Basin in Colorado and New Mexico, and the Black Warrior
Basin in Alabama. Hydraulic fracturing is or has been used to stimulate CBM wells in all basins,
although not frequently in the Powder River Basin. Table ES-1 lists the estimated number of active
producing wells, production volume of methane gas, and our understanding of hydraulic fracturing
activity in each of the eleven basins reviewed.
ES-2 What Is Hydraulic Fracturing?
Figure ES-2 illustrates a typical hydraulic fracturing event within a coalbed methane well. This
diagram shows the fracture creation and propagation, as well as the proppant placement and
fracturing fluid recovery stages.
A hydraulically created fracture acts as a conduit in the rock or coal formation that allows the
oil or coalbed methane (one source of natural gas) to travel more freely from the rock pores to
the production well that can bring it to the surface.
In the case of coalbed methane production, the gas is trapped in tiny, disconnected clusters of
fractures (called "cleats") within a coal layer. The coal layer is typically sandwiched between
Table ES-1. U.S. Coal Basins Production Statistics and Activity Information
Basin
San Juan
Black Warrior
Piceance
Uinta
Powder River
Central Appalachian
Northern Appalachian
Western Interior
Raton Basin
Sand Wash
Pacific Central
"Number of
Producing Wells
(Year 2000)
3,051
3,086
50
494
4,200
1,924
134
420
614
0
0
"Production of
CBM in Billions of
Cubic Feet
(Year 2000)
925
112
1.2
75.7
147
52.9
1.41
6.5
30.8
0
0
Does Hydraulic
Fracturing Occur?
Yes
Yes
Yes
Yes
Yes (in the past)
Yes
Yes
Yes
Yes
Yes (in the past)
Yes (in the past)
Data provided by GTI and EPA Region Offices
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-2
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EPA 816-D-02-006
Figure ES-1. Locus Map of Major U.S. Coal Basins
SASKATCHEWAN I MANITOBA 1
layers of dense rock, such as shale, sandstone or limestone, which prevents the coalbed methane
from migrating up and away from the coal. To extract the coalbed methane, a production well
is drilled through the rock layers to intersect the coal seam containing the gas. Next, a fracture
must be created in the coal seam to intersect the tiny, gas-bearing fractures and create a pipeline
through which the coalbed methane can travel to the well so it can be brought to the surface.
To create such a fracture, a thick, water-based fluid is pumped into the coal seam at a gradually
increasing rate. At a certain point, the coal seam will not be able to accommodate the fluid as
quickly as it is being injected. When this occurs, the pressure is high enough that a fracture is cre-
ated. A propping agent, usually sand (commonly known as "proppant"), is pumped into the frac-
ture so that when the pumping pressure holding the fracture open is released, the fracture does not
close completely because the proppant is "propping" it open. The resulting fracture filled with
proppant is a conduit through which coalbed methane trapped in the formation can flow to the well.
Production begins when pumping of the well begins. Ground water is produced from the coal
seam, decreasing the pressure and allowing methane to de-sorb from the coal matrix itself
(Gray, 1987). Contrary to conventional gas production, the percentage of water produced
declines with increasing coalbed methane production. In some basins, huge volumes of ground
water are produced from the production well.
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-3
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EPA816-D-02-006
Fracturing Fluid
Injection
Direction of Force
acting on formation
as a result of fluid pressure
Fracture
Propagation
Fracturing Fluid Injection:
1. Fracturing fluid is injected into the targeted
coal seam.
- Fluid causes a pressure buildup that creates
and propagates the fracture away from the well
perpendicular to the direction of least
principal stress.
Fracture Propagation:
2. Fluid mainly migrates in the direction of the
propagated fracture, however fluid leakoff
occurs out into the formation through
existing fractures.
Proppant Placement:
3. Once fracture propagation is complete,
gelled fluid carrying a proppant (typically sand)
is introduced into the formation to prop
the fracture open. Fracture propagation and proppant
injection are one continuous process.
..
Gelled Fluid
and Proppant Injection i
Not to
Fluid Recovery /
Dewatering
(Flowback)
Fluid Recovery / Dewatering
4. After completion of proppant placement, the fluids are pumped back
or recovered. Proppant remains in the fracture, along with some
entrapped fluids. Water is also extracted to reduce the hydrostatic
pressure in the formation so that gas flow can commence.
Entrapped
Fluid
Figure ES-2. A Graphical Representation of the Hydraulic Fracturing Process
in Coalbed Methane Wells
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-4
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EPA816-D-02-006
Hydraulic Fracturing
Well
>
Methane
Extraction
Methane Production
5. The flowback process initiates methane gas
flow out of the formation
Production from the well commences.
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-5
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EPA816-D-02-006
Figure ES-3. Direct Fluid Injection into
a USDW (Coal within USDW)
Stepl:
Fracture Fluid is Injected into Coalbed Seams
Fracture Fluid
Injected
Coalbed Methane
Production Well
ES-3 Why Is EPA Evaluating Hydraulic Fracturing?
EPA's Underground Injection Control (UIC) Program is authorized by the Safe Drinking Water
Act (SDWA) to protect public health from threats arising from contamination of USDWs result-
ing from underground injection activities. Underground injection is the subsurface emplacement
of fluids through a well bore. However,
SDWA does not authorize EPA to regu-
late oil and gas production practices.
A USDW is defined as an aquifer or it's
portion that:
A.
1. supplies any public water system;
or
2. contains sufficient quantity of
ground water to supply a public-
water system; and
i. currently supplies drinking
water for human consumption; or
ii. contains fewer than 10,000
milligrams per liter (mg/L) total
dissolved solids (IDS);
and
B. is not an exempted aquifer.
Although aquifers with greater than 500
mg/L IDS are rarely used for drinking
water supplies, it is believed that impos-
ing protection for waters with less than
10,000 mg/L IDS will ensure an ade-
quate supply (through treatment) for
present and future generations.
EPA initiated the hydraulic fracturing
study in response to concerned citizens
and the 11th Circuit Court's decision in
LEAF v. EPA, 118F.3d 1467, which
ruled that the State of Alabama must
regulate hydraulic fracturing in order to
retain authority of its State UIC
Program. Members of Congress also
wanted EPA to collect more information
to evaluate any public health risks asso-
ciated with hydraulic fracturing.
Direction of Ground Water Flow
Step 3:
Fluid Stranded as Production Resumes
Coalbed Methane
Production Well
Direction of Ground Water Flow
DRAFT Evaluation oflmpacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-6
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EPA816-D-02-006
This study is narrowly focused to address hydraulic fracturing of CBM wells. It does not
address all hydraulic fracturing practices, because (1) the 11th Circuit Court's decision was spe-
cific to CBM production; (2) CBM wells tend to be more shallow and closer to USDWs than
conventional oil and gas production wells (1,000s of feet below ground surface [bgs] rather than
10,000s of feet bgs); and (3) EPA has not heard concerns from citizens regarding any other type
of hydraulic fracturing. The study also does not address other concerns surrounding CBM pro-
duction such as ground water removal or production water discharge
Step 2:
Fracture Created
Coalbed Methane
Production Well
Water Supply Well
Direction of Ground Water Flow
Step 4:
Stranded Fluid Migration
Coalbed Methane
Production Well
Water Supply Well
Direction of Ground Water Flow
ES-4 What Was EPA's Project
Approach?
EPA designed the hydraulic fracturing
study to have three possible phases,
narrowing the focus from general to
more specific as findings warrant.
This report describes the findings
from the Phase I efforts, a limited-
scope assessment of potential threats
posed from hydraulic fracturing using
existing information.
The goal of EPA's hydraulic fracturing
Phase I study is to determine if a threat
to public health as a result of USDW
contamination from hydraulic fractur-
ing exists, and if so, is high enough to
warrant further study. The threat to
public health from USDW contamina-
tion was defined by the presence or
absence of documented contamination
cases stemming from hydraulic fractur-
ing, or a clear immediate contamina-
tion threat to drinking water wells.
EPA's approach for evaluating the
threat to public health was to review
claimed incidents of drinking water
well contamination as well as evalu-
ate the theoretical potential for
hydraulic fracturing to impact drink-
ing water wells. We evaluated two
potential mechanisms, illustrated in
Figures ES-3 and ES-4, by which
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-7
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EPA816-D-02-006
hydraulic fracturing may threaten USDWs: (1) the injection of fracturing fluids directly into a
USDW, and (2) the creation of a hydraulic communication through a confining layer between
the target coalbed formation and adjacent USDWs located either above or below.
ES-5 How Do Fractures Grow?
In many coalbed methane-producing
regions, the target coalbeds occur within
USDWs, and the fracturing process
injects stimulation fluids directly into
the USDWs. In other production
regions, target coalbeds are adjacent to
the USDWs that exist either higher or
lower in the geologic section. Vertical
fracture heights in coalbeds have been
measured in excess of 500 feet and
lengths can reportedly reach up to 1,500
feet. Fracture heights vary widely
depending on the basin geology. For
instance, in the Central Appalachian
basin, fracture heights can be as small
as two feet and lengths are typically in
the range of 200 to 300 feet from the
well bore (Halliburton, Inc., 2001).
Hydraulic fracturing in coalbed methane
formations in the Black Warrior basin
can create fractures that are taller than
they are long depending on the number
of coal seams targeted and the strength
of the intervening layers (Morales et al.,
1990; Zuber et al., 1990; Holditch et al.,
1989; Palmer et al., 1991, 1991a, 1993).
The potential exists for fractures to
extend from coalbeds into adjacent
USDWs, which could increase commu-
nication between stratigraphic sections.
Fractures generally will not penetrate
confining layers separating coalbeds and
overlying aquifers.
Once fracturing fluids are injected,
either directly or indirectly, local geo-
logic conditions may interfere with their
Figure ES-4. Fracture Creates Connection to USDW
Step 1:
Fracture Fluid is Injected into Coalbed Seams
Fracture Fluid
Injected
Coalbed Methane
Production Well
Water Supply Well
Direction of Ground Water Flow
Step 3:
Fluid Stranded as Production Resumes
Fracture Fluid
Extracted
Coalbed Methane
Production Well
Direction of Ground Water Flow
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-8
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EPA816-D-02-006
complete recovery. This may result in fracturing fluids being "stranded" in a USDW.
Subsequent coalbed methane production creates a flow back regime that should contain ground
water flow within the zone of influence surrounding the well. Any fluids not captured during
production are presumably trapped due to low permeability within the formation. Low perme-
ability limits ground water flow in both directions - toward the production well, which pulls
ground water toward it and away from the production well.
Step 2:
Fracture Created (Breaking Through Confining Unit)
Coalbed Methane
Production Well
Direction ol Ground Water Flow
Step 4:
Stranded Fluid Migration in Coal Formation and USDW
Water Supply Well
Coalbed Methane
Production Well
Direction of Ground Water Flow
The extent of a fracture is controlled
by the characteristics of the geologic
formation, the fracturing fluid type
used, the pumping pressure, and the
depth at which the fracturing is being
performed. The fracture initiates from
the well and extends out as two sepa-
rate wings in opposite directions.
Whether the fracture grows higher or
longer is determined by the surround-
ing rock properties. A hydraulically
created fracture will always take the
path of least resistance through the
coal seam and surrounding forma-
tions.
ES-6 What Is In Hydraulic
Fracturing Fluids?
Fracturing fluids consist of primarily
water or inert foam, such as nitrogen
or carbon dioxide. Fluids also usually
contain additives designed to improve
performance of the fluid. Components
of fracturing fluids are stored and
mixed on site (Figures ES-5 and ES-6
show fluids stored in tanks at CBM
well locations.) Table ES-2 lists addi-
tives available and any constituents of
concern that may be in the additives.
This information was obtained from
material safety data sheets (MSDS) by
EPA. Diesel fuel is the additive which
contains most of the constituents of
concern. It is used as an alternative to
a water-based polymer gel. Much
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-9
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EPA816-D-02-006
more gel can be dissolved in diesel as compared to water, reducing the cost required to transport
the fracturing fluids. Water and any additives are typically pumped from the storage tanks to a
manifold system placed on the production wells where they are mixed and then injected into the
coal formation (Figure ES-6). Coalbed fracture treatments typically use 50,000 to 350,000 gal-
lons of various fracturing fluids, and from 75,000 to 320,000 pounds of sand as proppant
(Holditch et al., 1988 and 1989; Jeu et al., 1988; Hinkel et al., 1991; Holditch, 1993; Palmer et
al., 1991, 1993, and 1993a). The volumes of constituents of concern and the ultimate concentra-
tion at which they are injected into the ground vary, but chemical additives make up only a small
fraction of the overall fluid mixture. EPA estimated the concentrations of chemicals of concern
in fracturing fluids at the point of injection using mid-range volumes reported by service compa-
nies. Table ES-3 presents the estimated concentrations and compares them to drinking water or
ground water standards.
Studies observed that for fracture stimulations in conventional production formations, 25 to 65
percent of fracturing fluids are recovered during flowback (Mukhergee et al. 1995; Samuel et al.
1997; Willberg et al. 1997 and 1998). In a study specific to coalbed methane production, Palmer
et al. (199 la) reported a 61 percent recovery of fracturing fluids after 20 days of production and
projected that 20 to 30 percent would remain in the formation. To inform our decision, EPA esti-
mated the concentrations of constituents of concern at the edge of a fracture considering only
dilution effects and assuming 60 percent of fluid was recovered. We estimated concentrations
decreased to 30
times less than those
at point of injection
- a significant drop
at a relatively short
mm I distance from the
' * m I production well.
i fmJmtmfm HJLfl I Any COtlStitUCIlt of
concern would have
^j^fj$ ^HPV^^^^H to migrate long dis~
tances, both vertical-
ly and horizontally,
before reaching an
exposure point.
Methane production
requires the removal
of ground water;
thus, in active
coalbed methane
wells the lowest
Figure ES-S. The fracturing fluids are stored on site in large, upright storage tanks
and in truck-mounted tanks.
pressure is typically in the CBM production well. Ground water will flow in the direction of the
lowest pressure. This pressure dynamic should prevent un-recovered fracturing fluids from
migrating beyond the influence of the CBM well.
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-IO
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EPA 816-D-02-006
ES-7 AreCoalbeds
Located within
USDWs?
EPA reviewed the
geology of eleven
basins to determine if
coalbeds are co-locat-
ed with USDWs and
to understand the
coalbed methane
activity in the area.
If coalbeds are locat-
ed within USDWs,
then any fracturing
fluids injected into
coalbeds have the
potential to contami-
nate the USDW. As
described previously,
a USDW is not nee-
Figure ES-6. The fracturing fluids, additives, and proppant are pumped from the
storage tanks to a manifold system placed on the wellhead where they are mixed
just prior to injection.
essarily currently used for drinking water and may contain ground water not suitable for drinking
without treatment. EPA found that ten of the eleven basins likely lie, at least in part, within
USDWs. Table ES-4 identifies coalbed basin locations in relation to USDWs, and summarizes
evidence used as the basis for the conclusions.
ES-8 Did EPA Find Any Cases of Contaminated Drinking Water Wells Caused by
Hydraulic Fracturing in CBM Wells?
EPA reviewed studies and follow-up investigations conducted by State oil and gas agencies in
response to citizen reports that CBM production resulted in water quality and quantity incidents.
EPA found no confirmed cases of drinking water well contamination or water loss as the result of
the hydraulic fracturing process.
EPA received reports of drinking water well problems associated with coalbed methane develop-
ment (see Table ES-5) from:
San Juan Basin (Colorado and New Mexico)
Powder River Basin (Wyoming and Montana)
Black Warrior Basin (Alabama)
Central Appalachian Basin (Virginia and West Virginia).
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-11
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EPA 816-D-02-006
Table ES-2. Summary of MSDSs1 for Hydraulic Fracturing Fluid Additives
Product
Linear gel delivery system
Water gelling agent
Linear gel polymer
Linear gel polymer slurry
Crosslinker
Crosslinker
Foaming agent
Foaming agent
Acid treatment - hydrochloric acid
Acid treatment - formic acid
Breaker Fluid
Microblclde
Biocide
Acid corrosion inhibitor
Acid corrosion inhibitor
Hazards Information
-Harmful if swallowed
-Combustible
-None
Flammable vapors
- Causes irritation if swallowed
Flammable
-Harmful if swallowed
-Combustible
- may be mildly imtating to eyes and skin
- may be mildly imtating if swallowed
- Harmful if swallowed
Highly flammable
Harmful if swallowed or absorbed
through skin
- May cause eye. skin and respiratory
bums
- Harmful if swillowed
- May cause mouth, throat, stomach, akin
and respiratory tract bums
May cause genetic changes
May cause respiratory tract, eye or skin
imuiion
Harmful if swallowed
May cause eye and skin irritation
- Causes set etc burns
-Harmful if swallowed
- May cause skin irritation
- May cause allergic reaction upon
repeated skin exposure
- May cause eye and skin irritation,
headache, dizziness, blindness and central
nervous system effects
-May be fatal if swillowed
- Flammable
- Cancer hazard (risk depends on duration
and level of exposure)
- Causes severe bums to respiratory tract,
eyes, skin
- Harmful if swallowed or absorbed
through the skin
Toxicological Information
- Chronic effects/Carcinogeniciiy
- Contains diesel, a petroleum distillate (known carcinogen)
- Causes eye, skin, respiratory imiation
- Can cause skin disorders
- Con be fatal if ingested
- May be mildly imuumg to eyes
- Con cause eye, skin and respiratory tract imuiion
- Carcinogenicity
- Possible cancer hazard based on animal data, diesel is listed as a
category 3 carcinogen in EC Annex 1
- May cause pain, redness, dermatitis
-Chronic elTecu/Carcinogenicity D5 may cause liver, heart, brain
reproductive system and kidney damage, birth defects (embryo
and fetus toucity)
-Causes eye, skin, respiratory irritation
-Can cause skin disorders and eye ailments
- May be mildly irritating
- Chronic effecis/Carcinogenicity
- May cause liver and kidney effects
- Causes eye, skin, respiratory imumon
- Con cause skin disorders and eye ailments
- May cause nausea, headache, narcosis
- May be mildly imiatmg
- Chronic efTects/Carcinogenicity
- Prolonged exposure can cause erosion of teeth
- Causes severe bums
- Causes skin disorders
- May cause heritable genetic damage in humans
- Causes severe bums
- Causes tissue damage
- May cause redness, discomfort, pain, coughing, dermatitis
- Chronic effects/Carcmogenicity
- Not determined
pain, nausea, and diarrhea if ingested
-Harmful if swallowed, large amounts may cause illness
- Imtam. may cause pain or discomfort to mouth, throat stomach,
may cause pain, redenss, dermatitis
- Chronic eirecls/Carcinogenicity - may cause eye. blood, lung.
liver, kidney, heart, central nervous system and spleen damage
- Causes severe eye, skin, respiratory irritation
- Can cause skin disorders
- Carcinogenicily - Thiourea is known to cause cances in animals.
and possibly causes cancer in humans
- Cotrosive - short exposure can injure lungs, throat, and mucous
membranes, can cause buras. pain, redness swelling and tissue
damage
Ecological Information
Skmly biodegradable
Biodegradable
- Not determined
- Palially biodegradable
- Not determined
-Partially biodegradable
- Low loxicity to fish
- Not deteimincd
- Harmful to aquatic organisms
-Not determined
- Not determined
- Not determined
- Not determined
-Not determined
- Not determined
- Tot ic to aquatic organisms
-Patiallybiodegradcable
1 MSDS ~ Material Safety Data Sheets lists of hazardous chemical constituents in industrial oroducls
They provide both workers and emergency personnel with the proper procedures for handling or working with a particular substance
MSDS's include information such as physical data (melting point, boiling point, flash point etc ). tosicity. health effects, first aid.
reactivity, storage, disposal, protective equipment, andspillflcak procedures
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
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Table ES-3. Estimated Concentrations at the Point of Injection of Constituents of
Concern in Hydraulic Fracturing Fluids
Product
Linear gel delivery system
Water 901111119 09^11
Lnear gel polymer
Geltng agents (BLM Lots)
Crosslmker
Crosslinker
Crosslinkera (BLM Lists)
Foaming agent
Foaming agent
Foamers (BLM Lists)
Add treatmenl hydrochloric sod
Acid treatment - formic Bad
Breaker Fluid
Breaker Fluids (BLM Lots)
MtcrobicKte
erode
Bademdas
Actd corrosion inhibitor
Acid corrosion inhibitor
MCL
RBC
MCP
Chemical Composition of Existing Products
Cherrucal Compound
guar gum derivative
desel
benzene
toluene
elhylbenzene
xytone
naptlutene
1-methyliiapthalene
2-methylnapthalene
dimethylnapthalenes
fluorenes
enjmatica
guar gum
water
nimancaod
fumancaad
adipic aod
benzene
ethylbenzene
methyl tart-butyl ether
napthakne
polynudear aromatic hydrocarbons (PAHs)
polycyctc organic matter (POM)
sodium hydiDMdo
toluene
flone
ooncBod
ethyfeneglycol
monoethanolainine
sodnun totraborote decahydrato
ammonium chbnde
zifcotuuiTt nitrate
zucontum sulfate
salt of alkyt amines
diGlhanokiininB
ethanol
2 NghM km a i amumnint
Concentrator of Interest (uglL)
Injection Concentration
31320
52200
52200
52200
14.09400
71,34000
34.974 00
270.57000
160.08000
31.32000
783000
57420000
495.04950
132.33787
529.351 49
306.25743
17099800
285.78842
na
na
234.945 16
na
na
236 081 75
269.641 08
na
na
na
na
na
na
na
na
na
na
236,070,00000
47,425.00000
na
210.750.00000
39,27500000
na
dwglng u> uriae* vm ilnbtd)
Vtglnbi WntVkglnlH
1 tor drlnUi? w
-------
EPA816-D-02-006
Table ES-4. Evidence In Support Of Coal-USDW Co-Location In U.S. Coal Basins
Basin
San Juan
Black Warrior
Piceance
Uinta
Powder River
Central Appalachian
Northern Appalachian
Western Interior
Arkoma
Cherokee
Forest City
Raton Basin
Sand Wash
Pacific Central
Is coal found
within the USDW?
Yes
Yes
Unlikely
Likely
Yes
Likely
Yes
Yes (in Arkansas)
Unlikely (in Oklahoma)
Yes
Unlikely
Yes
Yes
Yes
Explanation and/or evidence
A large area of the Fruilland system produces water containing less than 10.000 mg/L
TOS. the water quality criteria (or a USDW Analyses taken from a selected coal wen area
snow mat Die majority of wells (16 of 27 wells) produce water containing less than 10.000
mg/L TDS (Kaiser el el . 1994)
waters in the Pottsville flow systems contain less than 3,000 mg/L TDS, even within the
deeper, methane-target coal seams such as the Mary Lee beds (Pashm a al . 1991
Pashin and HinMe. 1997) In the early 1990's. several authors reported fresh water
induction from eoalbed wells at rates up to 30 gallons per minute (summarized In Pashin
etal.1991.Ellaidetal.1992)
. . .
system in the Green River Formation is approximately 6.400 feet The major eoalbed
methane target the Cameo-Wheeler-FairfieM coal zone lies roughly 6.000 feel below the
ground surface in a large portion of the basin (Tyler el al . 1998) A composite water
quality sample taken from 4,637 to 5,430 feet deep within the Cameo Coal Group In the
Williams Fork Formation exhibited a TDS level of 15,500 mg/L (Graham. COWR. personal
Piceance Basin a of such low quality that it must be disposed of in evaporation ponds or
re-injected into the formation from which it came, or at even greater depths (lessEn. 2001)
Blackhawk Formation appear to have TDS levels of about 5,000 mg/L (Quarterly Review,
1993)
A report prepared by the US Geological Survey showed that samples of water co-
produced from 47 COM wells in Ihe Powder River Basin all had a TDS of leas than
10,000 mg/1 (Rice et al . 2000)
The water produced by eoalbed methane wens n the Powder River Coal Field commonly
meets drinking water standards In (act production waters such as these have been
proposed as a separata or supplemental source for municipal drinking water in some
areas (DeBnnn et al . 2000)
Depths of coal groups are coinodent with fresh water in at least two of the slates within
Ihe overall basin (Ketafant el al 1988, Wilson. 2001. Foster. 1080. Hopkins, 1968 and
USGS, 1973)
seams (Wilson. VDMME. 2001)
The depth of each coal group wrihin (he basin is coinctdenl with the depths of USDWe
(Kelafant et el . 1988. Plan. 2001. Foster. 1980. HopUns 1998 USGS. 1973, Sedam and
Stem. 1970. USCS 1971, Ouigon. 1985)
Water quality data from eight historic Northern Appalachian Coal Basin projects show that
TDS levels were below 10.000 mg/L (Zebrownzet al . 1991)
The depths of coal beds wilhin Ihe State of Arkansas are coincident with depths to fresh
water (Andrews et al . 1998 Cordova. 1983. Fnedman. 1982 Quarterly Review, 1993)
Based on maps provided by the Oklahoma Corporation Commission (2001) as to Ihe
depths of Ihe 10.000 mg/L of TDS ground water quality boundary In Oklahoma. Ihe
location of eoalbed methane wells and USDWs would most likely not coincide In
Oklahoma This is based on depths to coals typically greater than 1 , 000 feet (Andrews el
al. 1998) and depths to Ihe base of the USDW typically shallower than 900 feet (OCC
Depth to Base of Treatable Water Map Series. 2001 )
The depths of coal beds within the Slate ol Kansas are coinodent with depths to fresh
water (Quarterly Review. 1993. McFartane. 2001. DASC. 2000)
deeper coalbeds within the basin (Bosbc et al. 1993, DASC. 2001 , Condra and Reed.
1959 Flowerdayetal.1998)
water quality results from eoalbed methane wells m the Raton Basin demonstrate TOS
content of less than 10.000 mg/L Nearly ill wells surveyed show a TDS of less than
2.500 mg/L. and more then half had TDS of less than 1.000 mgfL (Nat Wat Sum 1984)
Two gas companies produced water Irom coals that showed TDS levels below 10,000
mg/L
wells The wells yielded large volumes of fresh water with TDS <1 .000 mg/L (Colorado Oil
and Gas Commission web site, 200 1 )
Fueico was operating 11 wells along Cherokee arch Water pumped from Ihe wens
contained 1.800 mg/L of TDS and was discharged to the ground with a NPDES permit
(Quarterly Review, 1993)
Data demonstrating the co-locaton ol a coal seam and a USDW was found lor Pierce
County Water quality information from four gas test welts indicates TDS levels between
1330 and 1860 mg/L. well below 10.000 mg/L (Dion. 1984)
Wells in Ihe Basalts commonly yield 150 to 3.000 galons per minute Total dissolved
solids in the water produced generally range from 250 to 500 mg/L (Dion. 1984)
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-14
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EPA 816-D-02-006
Water quantity complaints are the most predominant cause for complaint by private well owners.
EPA received reports from concerned citizens from each area with significant coalbed methane
development. Taken on a case-by-case basis, investigations of water well contamination incidents
conducted by the states do not provide evidence that hydraulic fracturing of CBM wells has impact-
ed drinking water wells. Several other factors may contribute to ground water problems such as
various aspects of resource development, naturally-occurring conditions, population growth and
historical practices.
ES-9 What Are EPA's Conclusions and Recommendations?
EPA's approach for evaluating the threat to public health was an extensive information collec-
tion and review of empirical and theoretical data.
Based on the information collected, the threats posed by hydraulic fracturing of CBM wells to
USDWs are low, and do not justify additional study. A Phase II effort would not likely provide
any new information that would redirect the Phase I findings - those being a lack of contamina-
tion incidents and low potential for hydraulic fracturing to threaten human health through the
contamination of USDWs. Therefore, the apparent risk to public health from hydraulic fractur-
ing is not compelling enough to warrant expending resources on a Phase II effort.
Finally, it is important to note that States with primacy for their UIC programs enforce and have
the authority to place controls on any injection activities that may threaten USDWs. With the
expected increase in CBM production, additional data collection may become valuable in the
future, if development leads to injection of fracturing fluids into USDWs that are simultaneous-
ly used as drinking water sources. The Agency is committed to working with states to collect
relevant data to monitor this issue.
DRAFT Evaluation of Impacts to Underground Sources August 2002
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs ES-15
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EPA 816-D-02-006
Table ES-5. Summary of Reported Incidents that Associate Water
Quality/Quantity with Coalbed Methane (CBM) Activity
Basin
San Juan Basin
(New Mexico,
Colorado)
Powder River
(Wyoming, Montana)
Black Warrior
(Alabama)
Central Appalachian
(Virginia, West Virginia)
Water Contamination
Associated with Methane
Increased methane and
hydrogen sulfide in water wells,
pumphouses, and homes.
Claims of data showing
methane concentrations in
wells increased by 1000 ppm.
Improperly abandoned wells
lead to methane migration from
deep coal seams to shallow soils.
Methane causes drinking water
to froth and bubble.
Drinking water well was hissing
due to a high concentration of
methane gas. Water also had
a strong, unpleasant odor.
Well water contaminated by
methane gas had bad taste
and odor.
Water Contamination
Associated with
Fracturing Fluids
Information not available
Information not available
Citizen believes drinking water
well became contaminated with
a brown, slimy, petroleum-
smelling fluid after recovered
fracturing fluid drained from a
CBM well site to an area near
this homeowner's house.
Fish kills believed to be a result
of fracturing fluid discharged
into streams.
VA DMME states that soap
bubbles in residential water
fixtures are linked with
production well drilling.
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-16
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EPA 816-D-02-006
Water Contamination
Reported Without
Specific Mention of
CBM Activity
Appearance of anaerobic
bacteria in wells and
transient appearance of
particulates.
Black water believed to be
due to pulverized coal.
Cloudy water with grayish
sediment found 2 days
after fracturing.
Information not available
> Well water with milky
white substance and
strong odor.
> Well water with black
fines, globs of black
jellied grease and
smelted of petroleum.
> Well water turned brown
and had long, slimy tags
of floating gunk.
Private well contamination
by oily films, soaps, iron
oxides precipitates, black
sediments, bad odor and
taste, diesel fuel smells,
and murky water.
Soap bubbles flowing
from residential
household fixtures.
Resident provided EPA
with well water sample
that was translucent with
dark gray color and dark
black sediments.
Water Depletion or
Loss Associated with
CBM Activity
Complaints of loss of water
due to CBM development.
Loss of water in wells from
CBM development.
Aquifer dropped up to 200 feet
in some areas.
Information not available
Average of 10-12 complaints
per year to Virginia Dept of
Mines, Minerals, and Energy
involve reports of water
supplies diminishing or
disappearing entirely.
Over 380 homes in Buchanan
County without potable water as
a result of CBM development.
Non-Water Related
Impacts Associated
with CBM Activity
Impacted vegetation.
Discharged water creates
artificial ponds and swamps not
indigenous to region.
Coal ignites from lightning and
creates underground fires that
burn because of dewatered
aquifer. This creates toxins and
carcinogens that could
contaminate water.
Citizen believed recovered
hydraulic fracturing fluid was
allowed to run off-site.
She noticed animal/plant life
impacted.
Residents develop rashes from
showering.
Miner burned from acid that
seeped into mine shaft.
DRAFT Evaluation of Impacts to Underground Sources
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs
August 2002
ES-17
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EPA816-D-02-006
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DRAFT Evaluation of Impacts to Underground Sources August 2002
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs ES-18
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EPA 816-D-02-006
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DRAFT Evaluation of Impacts to Underground Sources August 2002
of Drinking Water by Hydraulic Fracturing of
Coalbed Methane Reservoirs ES-19
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