Thermal Treatment (in situ):
-- The steam remediation system consisted of a network of vertical wells and borings. 13 boreholes were used as injection or extraction wells and 10 boreholes were used as geophysical and/or temperature monitoring locations.
-- Steam was produced in an above ground steam generating unit, which transferred steam using a steam header at 690 kilopascal (kPa) gauge pressure (corresponding to a temperature of 170°C).
-- Steam injection rates varied from 27 to 508 kilograms per hour (kg/hr).
-At the injection wellhead, steam was reduced to pressures between 200 and 620 kPa (corresponding to 135 to 155°C) depending on the depth of delivery.
-- Air was injected in order to help develop fractures for improved steam injection rates, to create a buoyant vapor phase, and to assist in vadose zone flushing.
-- During operations, a total of 824,000 cubic meters of non-condensable vapor was extracted.
-- Over the course of the test, a total of 739,000 liters of water was extracted as liquid phase.
-- EPA's Office of Research and Development (ORD) National Risk Management Research Laboratory (NRMRL),
-- U.S. EPA Region 1,
-- Maine Department of Environmental Protection (MEDEP), the United States Air Force, and
-- EPA's Superfund Innovative Technology Evaluation (SITE) program.
U.S. Environmental Protection Agency
USEPA Robert S. Kerr Environmental Research Center
Ground Water and Ecosystems Restoration
P.O. Box # 1198
Ada, OK 74821-1198
Maine Department of Environmental Protection
17 State House Station
Augusta, Maine 04333-0017
USEPA, Region 1
1 Congress Street
Boston, MA 02114-2023
Steve Carroll & Gorm Heron
SteamTech Environmental Services, Inc.
4750 Burr Street
Bakersfield, California 93308
Phone: (661) 322-6478
Kingston, Ontario, Canada K7L3N6
Phone: (613) 533 6417
University of California, Berkeley
Berkeley, California 94720
Phone: (510) 642-2928
Volatiles-halogenated: 1,1-dichloroetheylene; benzene; chlorobenzene; cis-1,2-dichloroethylene; ethylbenzene; tetrachloroethylene; trans-1,2-dichloroethylene; toluene; trichloroethylene; vinyl Chloride; xylenes (total)
Past disposal practices of wastes from construction, industrial, and maintenance activities at the Base.
Type/Quantity of Media Treated:
Groundwater (quantity not documented).
Purpose/Significance of Application:
The main objectives of the study were to:
-- Develop an improved understanding of the mechanisms controlling DNAPL and dissolved phased contaminant behavior in fractured bedrock systems;
-- Evaluate how a remediation technology could be successfully implemented and controlled in a fractured bedrock environment;
-- Reduce the mass of contaminants in the subsurface to reduce the overall remediation timeframe; and
-- Evaluate characterization needs for fractured bedrock systems.
Regulatory Requirements/Cleanup Goals:
-- Based on the limited duration of the project it could not be determined conclusively that steam injection would be capable of heating the entire treatment area to the target temperature.
-- The vapor and water treatment system employed by the vendor effectively treated these effluent streams to meet discharge limitations.
-- For Steam Enhanced Remediation (SER) to be successful for the remediation of the site, extensive characterization would be needed and extremely long injection times would be required.
-- Further research is warranted on steam injection remediation in fractured rock at a less complex site.
The former Loring Air Force Base (AFB) is located in the northeastern portion of Maine, approximately 5 km west of the United States/Canadian border. A quarry at the site, located near the northwestern boundary, had historically been used for the disposal of wastes from construction, industrial, and maintenance activities at the Base. The site was added to the Superfund National Priorities List in 1990. During remedial activities in the 1990s, approximately 450 drums were removed from the quarry. The Record of Decision (ROD), signed in 1999, recognized that it was impractical at the time to restore groundwater in fractured rock to drinking water standards. However, an agreement was made between the Air Force, the MEDEP, and EPA Region 1 to use the quarry to conduct a research project to further develop remediation technologies for fractured bedrock. An evaluation of potential technologies to be tested at the site was issued in 2001, and SER was chosen from the proposals received.
Construction was initiated in August 2002 and extraction began on August 30, 2002. Steam injection was initiated on September 1, 2002, and continued until November 19, 2002, when funding for the project was no longer available. Extraction was terminated on November 26, 2002.
Based on the limited duration of the project, it could not be determined conclusively that steam injection would be capable of heating the entire treatment area to the target temperature. The vapor and water treatment system employed by the vendor effectively treated these effluent streams to meet discharge limitations. It was concluded that for SER to be successful for the remediation of the site, extensive characterization would be needed and extremely long injection times would be required. No cost information was provided.