Technology:
In Situ Chemical Oxidation (ISCO)
- Field demonstration of ISCO - source zone test plot was 75 ft by 50 ft by 45 ft deep
- A total of 842,985 gal of permanganate solution (1.4 to 2 percent) was injected into the test plot in 3 phases over a period of 8 months; vendor designed and supplied a continuous mix and automated feed system for the demonstration
- First injection September to October 1999 - a total of 304,763 gallons of solution were injected, first into the upper unit, then into the middle unit, followed by the lower unit; a GeoProbe equipped with a specially designed tip was used to inject the solution; the estimated radius of influence was 10-12 ft; however, local heterogeneities limited oxidant distribution in some areas
- The second (November 1999) and third (March to April 2000) injections - focused only on those portions of the plot where interim monitoring results showed that the area had not received sufficient oxidant during the previous cycle; a total of 87,483 gallons of solution were injected during the second cycle and 450,739 gallons during the third cycle
- One major system interruption occurred during the demonstration - hurricane in September 1999
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Cleanup Authority:
Not Provided
Contacts:
Arun Gavaskar
Project Manager
Battelle Memorial Institute
505 King Avenue
Columbus, OH 43201 |
Contaminants:
Halogenated VOCs
- TCE - Estimated mass of 6,122 kg in test plot
- DNAPL - 5,039 kg of the TCE mass was estimated to be DNAPL |
Waste Source:
Wastes from rocket engine and parts cleaning operations |
Type/Quantity of Media Treated:
Groundwater
- Test plot size - 75 ft by 50 ft by 45 ft |
Purpose/Significance of Application:
Field demonstration of ISCO to treat a DNAPL source area |
Regulatory Requirements/Cleanup Goals:
- The objective of the field demonstration was to reduce the contaminant mass by 90 percent |
Results:
- The mass of TCE and DNAPL was reduced by 77 percent and 76 percent, respectively; while less than the target of 90 percent, the removal percentage was considered to be significant for the technology
- The highest level of removal was observed in the upper sand zone, indicating that the oxidant distribution was most efficient in the coarser soils in this zone
- TCE and DNAPL removal pathways included destruction by oxidation, migration to the surrounding aquifer, and migration to the vadose zone and atmosphere
- Dissolved TCE levels decreased in most parts of the test plot, with several monitoring wells showing levels below the MCL of 5 ug/L |
Cost Factors:
- The total cost for the field demonstration was approximately $1 million, including costs for design, procurement, equipment and oxidant, mobilization/demobilization, and process monitoring
- The vendor indicated that about 15 percent of the cost was due to use of the technology at a demonstration rather than a full-scale application |
Description:
A 1998 site investigation at the Cape Canaveral Air Force Station in Florida identified a large DNAPL source at Launch Complex 34. Historical activities at the site included discharging wastes generated from rocket engine and parts cleaning operations into discharge pits. Chlorinated solvents, including TCE, were used in these cleaning operations. The Interagency DNAPL Consortium selected this site for demonstrating DNAPL treatment technologies. One of the technologies tested was in situ chemical oxidation (ISCO).
A field demonstration of ISCO was performed from September 8, 1999 to April 17, 2000, with the post- demonstration monitoring performed through February 2001. During the 8-month demonstration, more than 840,000 gallons of permanganate solution were injected in three phases. Following the first injection, monitoring results showed that local heterogeneities limited oxidant distribution in some areas. A second and third phase of injections were performed, focusing on those portions of the plot where interim monitoring results showed that the area had not received sufficient oxidant during the previous cycle. ISCO reduced the concentrations of dissolved TCE in the groundwater and reduced the mass of TCE and DNAPL in the test plot by 77 percent and 76 percent, respectively. While less than the target of 90 percent, the removal percentage was considered to be significant for the technology. The best distribution of the oxidant occurred in the upper sandy soils; distribution of oxidant was more difficult in finer-grained soils. Local geologic heterogeneities and native organic matter content may limit oxidant distribution in some regions. |
