Technology:
In Situ Chemical Reduction
- In situ chemical reduction using a ZVI slurry (FeroxSM process) with pneumatic fracturing was pilot tested at SA-2
- Pneumatic fracturing was performed using nitrogen gas injected into the ground at 120 pounds per square inch (psi). The gas was used to create preferential pathways in the low permeability, capillary fringe media above the rubble zone
- Following fracturing, ZVI powder was mixed with water under pressure to form a slurry; the slurry was injected into subsurface target intervals using the patented LAISM system; a specialized nozzle (capable of delivering the atomized fluids in up to a 360-degree pattern) was used to atomize the injected fluids to improve dispersal into the target zone
- 11,000 pounds of ZVI was injected to reduce 55 pounds of TCE; field ratio of iron to TCE by weight was 200:1; average slurry delivery pressure - 60 psi
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Cleanup Authority:
CERCLA
Contacts:
EPA Contact:
Julie Corkran, Ph.D.
Remedial Project Manager
U.S. EPA Region 4
4WD-FFB
61 Forsyth Street, SW
Atlanta, GA 30303-8960
Telephone: (404) 562-8547
Email: corkran.julie@epa.gov
State Contact:
Nelly Smith
Project Manager
Alabama Department of Environmental Management
1400 Coliseum Blvd.
Montgomery, AL 36110
Telephone: (334) 271-7750
Email: nfsmith@adem.state.al.us | Marshall Space Flight Center Contact:
Amy Keith
Project Manager
Building 4200, Room 436
MSFC, AL 35812
Telephone: (256) 544-7434
E-mail: amy.keith@msfc.nasa.gov |
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Contaminants:
Chlorinated volatile organics compounds (cVOCs)
- TCE in groundwater at concentrations as high as 72,800 ug/L |
Waste Source:
Historical solvent waste management practices from rocket engine testing operations |
Type/Quantity of Media Treated:
Groundwater
- Approximately 55 pounds of contaminants were estimated to be located in the residuum groundwater at demonstration area |
Purpose/Significance of Application:
Field demonstration of in situ chemical reduction using injection and reactive barrier wall to treat groundwater contaminated with cVOCs at a site containing UXO |
Regulatory Requirements/Cleanup Goals:
- The objective of the pilot test was to evaluate the effectiveness of in situ chemical reduction using the ZVI FeroxSM process to treat TCE in SA-2
- No specific cleanup targets were identified for the pilot test |
Results:
- During the period from July 2000 to March 2002, the ZVI chemical reduction pilot test in SA-2 reduced the concentrations of TCE in two source area monitoring wells by 52 and 90%, respectively
- TCE concentrations were reduced during the first 13 months after injection and then began to show increases, possibly indicating rebound; MSFC plans to continue groundwater monitoring on a quarterly basis to evaluate the potential for rebound
- As of March 2002, TCE degradation products, including DCE, VC, and chloride, were identified in the groundwater, and the redox potential for the groundwater changed to highly reducing conditions, indicating that the chemical reduction process was affecting groundwater quality |
Cost Factors:
- The cost to implement the pilot test was $27 per pound of ZVI injected
- The actual field demonstration portion of the test was approximately 70 percent of the total costs ($209,900), corresponding to about $19 per pound of ZVI injected |
Description:
The Marshall Space Flight Center (MSFC) is a federal research and development facility located within the Redstone Arsenal (RSA) in Huntsville, Alabama. During the 1940's, RSA was used for manufacturing munitions and from 1949 to 1960 for developing rockets and guided missile systems. Since 1960, when the civilian rocketry and mission activities were transferred to the National Aeronautics and Space Administration (NASA), MSFC has been used to support the space program, including developing spacecraft and rocket engines. Historical solvent waste management practices from rocket engine testing operations at MSFC resulted in contamination of soil and groundwater at the facility, primarily with chlorinated volatile organic compounds (cVOCs). Site investigations identified five major cVOC plumes at MSFC along with 14 contaminant source areas that may act as continuing sources of groundwater contamination.
A pilot test of in situ chemical reduction technology was performed to assess the ability of the technology to treat dissolved TCE in the residuum groundwater beneath the Source Area 2 (SA-2) area. SA-2 was the location of a pond (CERCLA Site MSFC-005) that had received TCE from engine cleaning operations and had overflowed through a concrete trough to surrounding soils. The presence of unexploded ordnance (UXO) within the subsurface beneath the SA-2 area affected the design and operation of the pilot test; clearance of all subsurface sampling, injection and permanent groundwater monitoring points was required the injection of ZVI slurry in many areas having the highest groundwater concentrations was limited. Through March 2002, the ZVI chemical reduction pilot test in SA-2 reduced the concentrations of TCE in two source area monitoring wells by 52 and 90%, respectively, and other parameters indicate that chemical reduction is occurring. Because of concern about possible rebound, MSFC plans to continue groundwater monitoring on a quarterly basis to evaluate the potential for rebound. |
