Cypress Village Shopping Center, Bridgeton, Missouri

State Coalition for Remediation of Drycleaners Site Profiles

Description
Historical activity that resulted in contamination.

The subject site is a 20-acre shopping center. The entire site is in the Voluntary Cleanup Program. The constituent of concern is tetrachloroethene due to operations from a former dry cleaning facility in this shopping center which operated from 1965 to 1980.

Remediation Status: Site closed

Contaminants
Contaminants present and the highest amount detected in both soil and groundwater.

Contaminant	Media	Concentration (ppb)
Tetrachloroethene (PCE)	groundwater	110,000 ppb
Trichloroethene (TCE)	groundwater
trans-1,2-Dichloroethene	groundwater
Vinyl Chloride	groundwater
1,2-Dichloroethene	groundwater

Site Hydrology

Deepest Significant Groundwater Contamination:		17ft bgs
Plume Size:		Plume Length: 150ft
Average Depth to Groundwater:		11ft

Lithology and Subsurface Geology

brown silty clay

Conductivity: 0.08ft/day
Gradient: 0.016ft/ft

Pathways and DNAPL Presence

Groundwater

Sediments

Soil

DNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?		Yes
How was the site evaluated?		Groundwater sampling,Compared sample concentration to screening criteria
Results of VI evaluation:		A potential VI pathway has been indentified
Has a vapor mitigation system been installed?		No

Remediation Scenario

Cleanup Goals:

Groundwater 5 µg/L Soil 55 mg/kg

Technologies

In Situ Monitored Natural Attenuation

Why the technology was selected:
MNA "strategy" initially selected and periodically monitored for approx 4 years. HRC injection needed for a short term cleanup to facilitate property sale.

Date implemented:
February 2003

Final remediation design:
Two injection patterns used: (1) CORE Area: a 900 sqft area around MW nearest former DC machine. 36 injection points on 5-foot centers; (2) SURROUNDING Area: 7200 sqft area (primarily downgradient) included 72 injection points on 10-ft centers. HRC was injected at a rate of 6 lbs per vertical foot of boring between approx 28 ft bgs and 13 ft bgs.

Results to date:
Concentrations of PCE and degredation products decreased drastically after HRC injection. Monitoring is ongoing.

Next Steps:
Completed 2 year monitoring program and final report in June 2005. PCE concentrations dropped from 64 ppm (pre-injection) to 2.7 ppm after 2 yrs. Site was closed (No Further Action letter)in March 2006 with Restrictive Convenant and AULs preventing (1) residential use of property and (2) domestic use of groundwater under the site.

Cost to Design and Implement:
Unknown

Costs

Cost for Assessment:		Unknown
Cost for Operation and Maintenance:
Total Costs for Cleanup:		Consultant: $164,000 Monitoring/Analysis: $81,000 Remediation/Misc: $130,000 Total: $375,000 (all costs approximate)

Lessons Learned

1.Nothing new was learned about groundwater during quarters 5 - 8. The remedy could have been selected a year earlier based on quarters 1 - 4.
2. HRC can work in a low permeability soil.

Contacts

Chris Cady, Ph.D, Environmental Specialist
Missouri Department of Natural Resources
Hazardous Waste Program/Voluntary Cleanup Program
PO Box 176
Jefferson City, MO 65102
(573) 526-8913

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