U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

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U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

State Coalition for Remediation of Drycleaners Site Profiles

Staten Island Cleaners, Florissant, Missouri

Historical activity that resulted in contamination.

The property has been developed as a retail shopping mall since 1968. The original dry cleaner building has been demolished and that area underlies part of current "Building K" and paved parking lot/drive adjacent to Building K. The owner agreed to install a vapor mitigation system in the subslab while Building K was under constuction since the site was under investigation.

Remediation Status: Site closed

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

Contaminant Media Concentration (ppb) Nondetect
cis-1,2-Dichloroethene groundwater
cis-1,2-Dichloroethene soil
1,1-Dichloroethene groundwater
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
Trichloroethene (TCE) groundwater
Trichloroethene (TCE) soil
trans-1,2-Dichloroethene groundwater
trans-1,2-Dichloroethene soil
Vinyl Chloride groundwater
Vinyl Chloride soil

Site Hydrology

Deepest Significant Groundwater Contamination:   7ft bgs
Plume Size:  
Average Depth to Groundwater:   6.75ft

Lithology and Subsurface Geology

  silty clay to clay with few inclusions
Depth: 0-30ft bgs
30ft thick
Gradient: 0.025ft/ft

Pathways and DNAPL Presence

DNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
How was the site evaluated?
  Compared sample concentration to screening criteria
Results of VI evaluation:
  A potential VI pathway has been indentified
Has a vapor mitigation system been installed?
Type of Vapor Mitigation System(s):
  Passive Vapor Barrier
Sub-slab Depressurization
Sub-slab Pressurization
Passive Venting
HVAC controls/modifications
Soil Vapor Extraction
Additional VI Information:
  Indoor air and subslab effluent air were tested using Summa cannisters. First samples were taken during active depressurization. Later the system blower was shut off and the system now operates passively. Building K is a retail clothing store and military recuiting office which is believed to have affected the indoor air with a variety of chemicals.

Remediation Scenario

Cleanup Goals:
  Missouri Risk-Based Corrective Action Tier I, non-residential use, silty soil, Indoor air level =
less than 0.009 mg/meter3 (air)
Remedy Level:
  Full Scale Remedy


Ex Situ Vapor Mitigation

Why the technology was selected:
The owner was in a hurry to construct on the site.

Date implemented:
July 2005

Final remediation design:
There is a collection pipe under the half of the building that was built on the former dry cleaner's location. It leads to one end of the building and vents above the roof. A blower unit was installed in the vent piping but was later bypassed to convert the system to passive operation. There is a cleanout access in the piping at ground level.

Results to date:
The system is still operating passively. It has had little to no effect on the contaminants underground. Indoor air test results are inconclusive as to the effect of venting because the system was installed during construction so there are no unvented samples for comparison but indoor air rarely showed traces of dry cleaning chemicals. The subslab effluent results indicated consistentlevels of tetrachloroethylene higher than the Tier I non-residential indoor air critera of less than 0.00909 mg/Kg/cubic meter. Trichloroethylene and vinyl chloride occasionally exceeded also.

Next Steps:
The site is closed based on a Tier 2 Missouri Risk-Based Corrective Action Risk Assessment. Indoor Air was not part of the Tier 2 assessment as it was considered an incomplete pathway due to the mitigation.


Cost for Assessment:
Cost for Operation and Maintenance:
Total Costs for Cleanup:
  Environmental Consulting Services - $134,246.43 Lab Analysis - $20,772.72 Equipment Rental/Lease/Purchase - $10,336.17 Disposal/Treatment - $2,872 Groundwater Monitoring - $4,845 Operations & Maintenance - $23,378.75 Soil Boring/Monitoring Well Installation - $19,271.16 Remediation Activities - $52,044.44 Other Costs/Permits - $492.06 Site Restoration - $1,130 Grand Total - $269,388.75

Lessons Learned

The system has had problems with water pooling in the low point where the cleanout is. Depending on how much water collects, it could block airflow.


Vicky Kugler
Missouri DNR Hazardous Waste Program
P.O. Box 176
Jefferson City, MO 65102


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