EPA/600/S-09/030
ŁEPA
www.epa.gov/ord
science in ACTION
DRINKING WATER RESEARCH
PROGRAM
USE OF SOIL-GAS, GAS FLUX, AND GROUND-WATER MONITORING TO
EVALUATE POTENTIAL LEAKAGE TO UNDERGROUND SOURCES OF
DRINKING WATER, THE ATMOSPHERE, AND BUILDINGS DURING
GEOLOGICAL SEQUESTRATION OF CARBON DIOXIDE
Issue:
Geological sequestration (GS) is
recognized as the injection and
subsequent long-term trapping of
gaseous, liquid, or supercritical
carbon dioxide (CO2) in
subsurface media - primarily
saline formations, depleted or
nearly depleted oil and gas
reservoirs, and coal seams.
Carbon capture, transport, and
storage via GS from stationary
sources of CC>2 such as refineries,
and coal-fired electric, ethanol,
cement, and fertilizer plants could
allow continued use of fossil fuels
in a manner that greatly reduces
CC>2 emissions until alternative
energy sources are deployed on a
large scale in the coming decades.
It is widely acknowledged that
leakage through transmissive
faults (and associated fractures)
and well penetrations
(operational, non-operational, and
abandoned wells) are the most
likely potential pathway for CC>2
release from a storage formation
at a properly selected site for GS.
Leakage through transmissive
faults and well penetrations could
result in intrusion of CC>2 or brine
into underground sources of
drinking water (USDWs), release
of CC>2 to the vadose zone and the
atmosphere, and intrusion of CC>2
into buildings. Release of CC>2 or
brine into a USDW could be
accompanied by measurable
alteration in pH, major ions, and
mobilization of hazardous
inorganics. Release of CC>2 into
the vadose zone could be
accompanied by compositional
changes in soil gas and flux to the
atmosphere. Release of CO2 into
buildings could result in increased
CC>2 and potential reduction in
oxygen in indoor air.
Scientific Objective:
The U.S. Environmental
Protection Agency's (EPA) Water
Research Program in the Office
of Research and Development is
conducting research to better
detect and quantify leakage into
USDWs, the vadose zone, the
atmosphere, and buildings.
Research in this initiative is
focused in three topical areas:
. Evaluation of Leakage
through Well Penetrations
Soil-gas, gas flux, and
ground-water monitoring will
be conducted at an enhanced
oil recovery site and/or a site
where CC>2 will be injected
into a saline aquifer to assess
the potential for leakage from
well penetrations, especially
abandoned wells.
Measurements will be
conducted near and away
continued on back
U.S. Environmental Protection Agency
Office of Research and Development
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&EPA
www.epa.gov/ord
DRINKING WATER RESEARCH PROGRAM
continued from from
from well penetrations to
detect "spot anomalies" prior
to and during injection of
CO2. This concept is similar
to the use of soil-gas surveys
to locate gas release from
faults and fractures in
volcanic or geothermal areas
where magna degassing or
thermo-metamorphic
alteration of carbonates
produces large volumes of
CC>2 and the use of soil-gas
surveys for mineral or
petroleum/natural gas
exploration.
Gas Intrusion
Intrusion of sub-surface gases
into buildings will be
evaluated at a housing
division near Wichita, Kansas
where depletion of oxygen
and buildup of CC>2 has been
documented in indoor air after
a heavy infiltration event.
This study will serve as a
natural analogue to evaluate
potential CC>2 intrusion into
buildings due to GS. During
commercial application of
GS, it will be necessary to
have a protocol to discern the
cause of elevated levels of
CC>2 to avoid an unnecessary
shut down of a GS system and
potential public overreaction.
. Soil-Gas Method
Development
Despite the long-term use of
soil-gas sampling to support
resource exploration and
hazardous waste
investigations, quality
assurance and control
measures are poorly
documented or lacking.
Research on leak, purge, and
gas permeability testing, will
be conducted to support
application of GS.
The National Risk Management
Research Laboratory (NRMRL)
has a long history of conducting
research on subsurface gas flow
(DiGiulio and Varadhan, 2001),
gas and vapor intrusion (DiGiulio
et al., 2006a), and soil-gas
sampling (DiGiulio et al. 2006b).
Application and Impact:
The outcomes of this research,
conducted through the Drinking
Water Research program, will be
used to develop cost-effective
protocols for monitoring GS
systems. Decreased cost will lead
to increased implementation and
protection of public health and
the environment.
REFERENCES:
DiGiulio, D.C., C. Paul, R. Cody, R. Willey, S.
Clifford, P. Kahn, R. Mosley, A. Lee, and K.
Christensen. 2006a. Assessment of vapor intrusion
in homes near the Raymark Superfund Site using
basement and sub-slab air samples. EPA/600/R-
05/147, U.S. Environmental Protection Agency,
Office of Research and Development, National
Risk Management Research Laboratory.
DiGiulio, D.C., C. Paul, B. Scroggins, R. Cody, R.
Willey, S. Clifford, R. Mosley, A. Lee, K.
Christensen, and R. Costa. 2006b. Comparison of
Geoprobe PRT, AMS GVP soil-gas sampling
systems with dedicated vapor probes in sandy soils
at the Raymark Superfund Site. EPA/600/R-06/11,
U.S. Environmental Protection Agency, Office of
Research and Development, National Risk
Management Research Laboratory.
DiGiulio, D.C. and R. Varadhan. 2001.
Development of recommendations and methods to
support assessment of soil venting performance
and closure, EPA/600/R-01/070, U.S.
Environmental Protection Agency, Office of
Research and Development, National Risk
Management Research Laboratory.
CONTACTS:
Dominic C. Digiulio, Ph.D., EPA's Office of
Research and Development, U.S. Environmental
Protection Agency, 580-436-8605,
digiulio.dominic(g!epa. gov
Richard T. Wilkin, Ph.D., EPA's Office of
Research and Development, U.S. Environmental
Protection Agency, 580-436-8874,
wilkin.rick(g!epa. gov
Robert W. Puls, Ph.D., EPA's Office of Research
and Development, U.S. Environmental Protection
Agency, 580-436-8543, puls.roberttgiepa.gov
Audrey D. Levine, Ph.D., EPA's National Program
Director, Drinking Water Research Program
202-564-1070, levine.audrey(g),epa.gov
U.S. Environmental Protection Agency
Office of Research and Development
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