Pump and Treat of Contaminated Groundwater at the Solid State Circuits Superfund Site, Republic, Missouri

Site Name:

Solid State Circuits Superfund Site

Location:

Republic, Missouri

Period of
Operation:

Status: Ongoing
Report covers: 1993 - 3/97

Cleanup
Type:

Full-scale cleanup (interim results)

Vendor:

Steve Chatman
Chatman & Associates
647 Massachusetts Ave., Ste. 211
Lawrence, KS 66044-2250
(785) 843-1006

Technology:
Pump and Treat

- Groundwater is extracted using 7 wells, 4 located on site and 3 located off site, at an average total pumping rate of 34 gpm
- Three wells have depths of 90 ft bgs, two wells of approximately 300 ft bgs, one of 600 ft bgs, and one of 985 ft bgs
- Groundwater extracted from on-site wells is treated with air stripping and discharged to a POTW
- Groundwater extracted from off-site wells is discharged without treatment to a POTW

Cleanup Authority:
CERCLA Remedial
- ROD Date: 9/27/89

EPA Point of Contact:
Steve Auchterlonie, RPM
U.S. EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7778

Facility Engineer:
Greg Vierkant
Lucent Technologies
2101 West Chesterfield Blvd.
Suite C100-110
Springfield, MO 65807-8672
(417) 882-2211
State Point of Contact:
Candice Hamil
Missouri Dept. Of Nat. Resources
205 Jefferson Ave., P.O. Box 176
Jefferson City, MO 65101
(314) 751-3176 or (800) 334-6946

Contaminants:
Chlorinated solvents

- Contaminants of greatest concern at this site are TCE, 1,1-DCA, 1,1-DCE, methylene chloride, 1,1,1-TCA, and vinyl chloride
- Maximum concentration of TCE was 290,000 µg/L

Waste Source:
Storage of stripper and plating wastes in sump pit

Type/Quantity of Media Treated:
Groundwater

- 257 million gallons treated as of March 1997
- DNAPL suspected in groundwater on site
- Extraction wells are located in 3 aquifers, which are influenced by a nearby surface water
- Groundwater is characterized as a leaky artesian system occurring in karst formations, with three units identified at the site
- Hydraulic conductivity ranges from <0.01 to 1.62 ft/day

Purpose/Significance of Application:
Groundwater characterized as a leaky artesian system occurring in a karst formation.

Regulatory Requirements/Cleanup Goals:
- The remedial goals for this site are to reduce the TCE concentration in groundwater to 5 µg/L and maintain hydraulic control over the groundwater contaminant plume.
- Performance goals were that TCE levels in individual discharge points to the POTW were below 200 µg/L, and that average water levels and pump rates from specific wells be within specified ranges; these latter requirements were to ensure hydraulic containment.

Results:
- TCE concentrations in some of the wells have decreased from 1987 to 1996, and are below the cleanup goal in one well, however, TCE concentrations in most wells remain well above the cleanup goal.
- From March 1988 through March 1997, 2,754 pounds of TCE were removed from the groundwater.
- Plume containment has been achieved for this site.

Cost Factors:
- Actual costs for the P&T system were approximately $2,510,400 ($893,700 in capital and $1,616,700 in O&M), which correspond to $10 per 1,000 gallons of groundwater extracted and $913 per pound of contaminant removed.
- The capital costs do not include the costs for installation of the four deeper wells; these costs were accounted for as part of the RI/FS and are not included in the total cost shown above.

Description:
From 1968 through November 1973, Solid State Circuits manufactured circuit boards and used TCE as a cleaning solvent in portions of its manufacturing process. Since 1973, the site was occupied by a number of tenants, including Micrographics, Inc., a photographic processing firm. In November 1979, a fire partially destroyed the building, and the debris was pushed into the basement under the remaining portion of the building. In June 1982, the Missouri Department of Natural Resources collected samples of water from the city's three municipal wells and detected elevated concentrations of TCE in one well located 500 ft from the site. In 1984, MDNR investigated the site and found elevated levels of TCE in the fill dirt and rubble from the basement, in a 540 ft deep well in the basement, and in shallow groundwater outside the building. The site was placed on the NPL in June 1986 and a ROD was signed in September 1989.

The groundwater is characterized as a leaky artesian system occurring in karst formations, with three units identified at the site, with shallow and deep bedrock zones extending up to 1,500 ft bgs. The groundwater extraction system consists of seven wells, one of which is a municipal well. Extracted groundwater is treated using air stripping. After nine years of operation, cleanup goals for TCE have not been achieved. Site operators are evaluating innovative technologies to enhance the remedial effort, such as air sparging using a horizontal well.