Technology:
- In Situ Redox Manipulation (ISRM) to treat soil and groundwater in the source area and downgradient
- Treatment of source area proceeded in two steps – 1) ECOBOND® reagent injection to reduce hexavalent chromium to trivalent chromium, followed by 2) cement-based grout injections to provide structural strength to treated soil
- ECOBOND® is a proprietary sulfur-based reagent that reduces hexavalent chromium to trivalent chromium.
- Treatment depth at the source area ranged between 20 and 33 feet deep
- The application used a 10-foot diameter auger to perform in situ vertical auger mixing; the auger size was reduced to a 6-foot diameter to reach depths below 25 feet
- An ISRM treatment wall was installed to treat migrating chromium from the source area
- The wall consisted of a series of eight pairs of injection wells (16 wells total)
- Each pair of injection wells had one deep well (screened 28 to 33 ft bgs) and one shallow well (screened 23 to 28 ft bgs)
- Approximately 5,700 gallons of sodium dithionite reagent was mixed with water and injected into each well pair (40,000 gallons total)
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Cleanup Authority:
State lead
- Record of Decision for Soil/Source control (OU1) issued in December 1987
- Record of Decision for groundwater (OU2) issued in July 1988
- Record of Decisions (OU1 and OU2) amended to include in situ chemical reduction of hexavalent chromium to trivalent chromium in August 30, 2001
Contacts:
EPA Contact:
Sean Sheldrake
Site Manager
EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
Telephone: (206) 553-1220
E-mail: sheldrake.sean@epa.gov
State Contact:
Barnett Guy
Washington State Department of Ecology
Southwest Regional Office
300 Desmond Drive
Lacey, WA 98503
Telephone: (360) 407-7115
E-mail: gbar461@ecy.wa.gov
Oversight Contractor
Larry Vanselow
Project Manager
Weston Solutions, Inc.
190 Queen Anne Avenue North, Suite 200
Seattle, WA 98109-4926
Telephone: (206) 521-7692
E-mail: Larry.vanselow@westonsolutions.com
On-site Contractor
Mark A. Fleri, PE
Vice President
Compass Environmental Inc.
2075 West Park Place
Stone Mountain, Ga 30087
Telephone: 770.879.4075
E-mail: mfleri@compassenvironmental.com |
Contaminants:
Heavy Metals (Chromium)
- Total chromium concentrations in soil as high as 7,500 mg/kg
- Total chromium concentration in the groundwater at the ISRM treatment wall as high as 300,000 µg/L |
Waste Source:
Discharge of wastes from the chromium plating operations to an on-site dry well. |
Type/Quantity of Media Treated:
Soil and Groundwater
- 20,962 cubic yards of contaminated soil treated
- 185,000 gallons of contaminated groundwater treated |
Purpose/Significance of Application:
To treat source area soil by reducing hexavalent chromium to trivalent chromium, and to treat migrating chromium from the source area. |
Regulatory Requirements/Cleanup Goals:
- The cleanup goals for soil were 19 mg/kg of hexavalent chromium and 80,000 mg/kg of trivalent chromium.
- The cleanup goal for groundwater was 50 µg/L of total chromium. |
Results:
The total chromium concentration in soil at the source area was reduced from as high as 7,500 mg/kg to non-detect (< 5 mg/kg), and from 300,000 µg/L to less than 800 µg/L in the groundwater. Total chromium concentration in the groundwater at the ISRM treatment wall was reduced from as high as 300,000 µg/L to 25 µg/L. |
Cost Factors:
ISRM treatment wall
Total capital costs in 2003 dollars were $350,300. Total operating and maintenance costs (O&M) costs were $679,700. The cost per square foot of the treatment wall was $330.
Source area treatment
Total capital costs in 2003 dollars were $398,000. Total O&M costs were $2,021,500. The cost per cubic yard of treated soil was $124. |
Description:
The Frontier Hard Chrome (FHC) Superfund site was used for chrome plating operations from 1958 to 1983. Since 1983, the site has been leased and most recently used as a metals shop.
Discharge of wastes from the chrome plating operations resulted in soil and groundwater contamination at the site. Total chromium concentrations in soil were found to be as high as 7,500 mg/kg, and as high as 300,000 µg/L in groundwater at the treatment wall. Soil at the site was also contaminated, with chromium concentrations as high as 7,500 mg/kg. In September 1983, the site was added to the National Priorities List. Records of Decision (RODs) were issued in December 1987 for the soils/source control operable unit (OU1) and in July 1988 for the groundwater operable unit (OU2). In Situ Redox Manipulation (ISRM) was selected to treat soil and groundwater contamination at the site. From January to September 2003, the remedial action was conducted in three phases: building demolition, ISRM treatment wall installation, and source area treatment. ECOBOND®, a proprietary sulfur-based reagent was used to treat the source soil by reducing hexavalent chromium to trivalent chromium. The ISRM treatment wall was installed to treat migrating chromium from the source area.
Approximately 20,962 cubic yards of contaminated soil and 185,000 gallons of contaminated groundwater were treated at the source area. Total chromium concentrations in soil were reduced from as high as 7,500 mg/kg to non-detect (< 5 mg/kg). Total chromium concentrations in groundwater were reduced from as high as 300,000 µg/L to less than 800 µg/L (detection limit using HACH chromium test kits). At the ISRM treatment wall, total chromium concentrations in the groundwater were reduced from as high as 300,000 µg/L to 25 µg/L.
The total capital costs and O&M costs for the treatment of source area in 2003 dollars were $398,000 and $2,021,500, respectively. The cost per cubic yard of treated soil was $124. The total capital costs and O&M costs for the treatment wall in 2003 dollars were $350,300 and $679,700, respectively. The cost per square foot of the treatment wall was $330. |
