Steam Injection into Fractured Limestone at Loring Air Force Base

Steam Injection into Fractured Limestone at Loring Air Force Base
EvaL. Davis, Ph.D, USEPA/ORD/NRMRL/GWERD, Gorm Heron, SteamTech Environmental Services,
and Steve Carroll, SteamTech Environmental Services
A research project on steam injection for the remediation of spent chlorinated solvents from fractured
limestone was recently undertaken at the former Loring AFB in Limestone, ME. Participants in the project
include the Maine Department of Environmental Protection, EPA Region I, the Air Force, EPA's Office of
Research and Development, and SteamTech Environmental Services. In addition, expert advise on
characterization of fractured rock and steam injection was provided by researchers from Queen's
University and the University of California - Berkeley. The primary objective of the project was to
facilitate development of promising technologies for bedrock remediation while reducing the amount of
mass remaining in the subsurface at this site.
Site History and Characterization
The Quarry was located in the northwest corner of the former Loring AFB, and was used as a source of
limestone gravel for the base, and at some time drums of spent chlorinated solvents from base operations
were stored or disposed of there. During the 1990s, approximately 450 drums were removed from the
upper tier of the Quarry. Subsequent investigation of the groundwater revealed concentrations of
tetrachloroethene at levels that would indicated the presence of nonaqueous phase liquids (NAPLs). Other
contaminants found in the groundwater included trichloroethene, carbon tetrachloride, and BTEX.
Characterization of the fracture system indicated a very complex system with the presence of three different
fracture systems as well as several faults. Fracturing within the treatment zone, however, was sparse.
Groundwater flow is believed to be controlled by bedding plane fractures.
The Steam Injection Research
In Summer 2001, installation of a steam injection system aimed at the area where high levels of PCE and
TCE were known to exist in groundwater in the fractured limestone was initiated. As boreholes were
installed of the system, characterization of the contaminant distribution, the fracture system, and the
hydrogeology was undertaken. Based on the results of the characterization activities, the injection and
extraction system was redesigned, based on injecting steam into the relatively clean boreholes, and
extracting contaminants from the most highly contaminated boreholes. Steam injection was initiated in
September 2002 and continued for 80 days. Temperature distribution in the subsurface and the extraction
rate of contaminants was monitored, and changes were made to the system to optimize the amount of steam
injected into the system and the amount of contaminants recovered. After the funding for the research was
exhausted and the injection terminated, extraction continued for an additional 7 days, and periodic
temperature monitoring was continued for an additional 3 months. During the Summer of 2003, post-
treatment groundwater and rock core samples were obtained and analyzed. Data is being compiled to
describe heat flow in the fractured rock system, as well as the flow and transport of contaminants in the
aqueous and vapor phase. This presentation will describe the design of the steam injection system and
what was learned about steam and contaminant movement in fractured limestone during the steam
injection.
This is an abstract for a proposed presentation and does not necessarily reflect EPA policy.
683

-------
Dr. Eva Davis received a Ph.D in Agricultural Engineering from Colorado State University in
1990, with a specialization in groundwater contamination. Since that time, she has worked for
the US Environmental Protection Agency doing research and technical support for thermal
remediation of soils and aquifers. Her research has focused on temperature effects on the
properties of organic contaminants, temperature effects on flow in porous media, hot water
injection for remediation, and steam injection treatability studies. Her technical support activities
include site specific consulting to assess sites for the applicability of thermal remediation, site
characterization to support application of the technologies, and operational support for sites with
a variety of contaminants and in a range of geologic settings.
Dr. Gorm Heron is the principal engineer and scientist for SteamTech Environmental
Services. He has been the lead designer on the seven field projects conducted since 1998. Prior
to this, Dr. Heron was a research engineer at UC Berkeley, and a post-doctoral researcher at the
USEPA Kerr Research Center in Ada, Ok. He has worked on thermal remediation since 1995.
He holds an Master of Science in Civil Engineering (1990) and a Ph.D in Environmental Science
and Engineering from Technical University of Denmark (1994).
Dr. Steve Carrroll has been the lead geologist for seven field implementations of thermal
remediation since 1999. In addition, he was the project manager for three thermal remediation
projects between 2001 and the present. He is the lead geologist and geophysicist for SteamTech
Environmental Services. Dr. Carroll holds a Ph.D in Geology from University of Aberdeen
(1992) and a Bachelor of Science in Geology from University of Glasgow (1987).
Eva Davis, Ph.D, Hydrologist
USEPA/ORD/NRMRL/GWERD
RS Kerr Environmental Research Center
PO Box 1198
Ada, OK 74820
(580) 436-8548
(580)436-8703
Gorm Heron, Ph.D
SteamTech Environmental Services, Inc.
4750 Burr Street
Bakersfield, CA 93308
(661) 322-6478
(661)332-6552
Steve Carroll, Ph.D
SteamTech Environmental Services, Inc.
4750 Burr Street
Bakersfield, CA 93308
(661) 322-6478
(661)332-655
684

-------