Pump and Treat and Soil Vapor Extraction at the Commencement Bay South Tacoma Channel Superfund Site, Tacoma, WA

Site Name:

Commencement Bay South Tacoma Channel Superfund Site

Location:

Tacoma, WA

Period of
Operation:

November, 1998 - Ongoing
(data available through June 2000)

Cleanup
Type:

Full scale

Technology:
Pump and Treat of Groundwater:
- Groundwater extraction began in November, 1988 using a single well designed to yield 500 gallons per minute (gpm). In August 1995, 4 additional wells designed to yield 50 gpm each also began extracting groundwater.
- extracted groundwater is treated using two granular activated carbon (GAC) adsorption vessels connected in series, each of which contain about 20,000 pounds of GAC.

Soil Vapor Extraction (SVE)
- The SVE system consisted of 23 vapor extraction wells in the vadose zone and a carbon adsorption system to treat the vapors.
- The design air flow rate for the system was 3,000 standard cubic feet per minute.
- The SVE system operated between August1993 and May1997.

Cleanup Authority:
CERCLA - Remedial Action
- ROD signed 1985

Pump and Treat
System Operation Contractor:

URS Greiner, Inc. (URSG)
(Point of contact not provided)

SVE System Contractor:
Environmental Science and Engineering, Inc.
(Point of contact not provided)
EPA Contact:
Kevin Rochlin
Remedial Project Manager
U.S. EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
Phone: (206) 553-2106
rochlin.kevin@epa.gov

Contaminants:
Chlorinated Volatile Organic Compounds (VOCs)
- 1,1,2,2-Tetrachloroethane (PCA) - 17 to 300 µg/L
- trans-1,2-Dichloroethene (DCE) - 30 to 100 µg/L
- Trichloroethene (TCE) - 54 to 130 µg/L
- Tetrachloroethene (PCE) - 1.6 to 5.4 µg/L
- vinyl chloride (concentration not specified)
- The presence of light and dense non-aqueous phase liquids has been confirmed at the site

Waste Source:
Oil recycling, paint and lacquer thinner manufacturing, oil canning, and heating, ventilation, and air conditioning equipment warehousing

Type/Quantity of Media Treated:
Groundwater and Soil
- 450 million gallons of groundwater treated through May 2000

Purpose/Significance of Application:
Remediation of groundwater and soil contaminated with chlorinated VOCs using pump and treat and SVE

Regulatory Requirements/Cleanup Goals:
- Groundwater extraction rate (100 to 500 gpm)
- Aquifer remedial goals in µg/L - PCA (0.219), PCE (5), TCE (5), trans-1,2-DCE (100), cis-1,2-DCE (70), vinyl chloride (2)
- Performance standard for reinjection of treated groundwater in µg/L - PCA (10.7), PCE (8.85), TCE (80.7), trans-1,2-DCE (1.85), vinyl chloride (100), total VOCs (193)
- Performance standard for discharge of treated groundwater to surface water in µg/L - PCA (6.48), PCE (4.15), TCE (55.6), trans-1,2-DCE (32,800), vinyl chloride (2.92)
- Performance standards for the SVE system were not specified.

Results:
- Actual groundwater extraction rate is less than 100 gpm. Iron fouling likely is a primary cause of the low extraction rate.
- About 15,000 pounds of VOCs had been removed from groundwater by the pump and treat system through December 2000.
- As of June 2000, concentrations of PCA, TCE, and total-1,2-DCE in the extraction wells remained above the remedial goals. Information on the concentrations of other contaminants were not provided.
- The size of the TCE and DCE contaminant plumes have decreased from 1993 to 1998.
- The above ground treatment system routinely met performance standards.
- The RPM indicated that the current pump and treat system will not attain the aquifer remedial goals due to the presence of light and dense non-aqueous phase liquids.
- The SVE system removed approximately 54,100 pounds of VOCs from subsurface soils at the site.

Cost Factors:
Pump and Treat System:
- Total capital costs through May, 2000 were $1.8 million
- Total year 2000 operating costs were $0.41 million
Cost information was not provided for the SVE system.

Description:
From the 1920s to 1976 site operations included oil recycling and manufacturing of thinner for paint and lacquer. From 1976 to 1995, site operations were limited to canning new oil brought to the site in bulk containers. The facility has been used as a warehouse for heating, ventilation, and air conditioning equipment since 1995. Both shallow soil, subsurface soil, and groundwater at the site were contaminated with volatile organic compounds (VOCs), including chlorinated solvents.

SVE was used from 1993 to 1997 to treat soil at the site. A pump and treat system for groundwater was installed and began operating in 1988. Operation of the pump and treat system was ongoing as of June, 2000. Through December 2000, the pump and treat system had removed about 15,000 pounds of VOCs, and the SVE system had removed another 54,100 pounds of VOCs during its operation. However, the presence of light and dense non-aqueous phase liquids provide continuing sources of dissolved phase contaminants, and remedial goals for the aquifer are not expected to be met using pump and treat. Future plans for the site are being evaluated to determine the optimal approach to address site-related contamination.