Drycleaner Site Profiles

American Cleaners, St. Peters, Missouri

Description
Historical activity that resulted in contamination.

American Cleaners was a former perchloroethylene (PCE) drycleaning facility that operated from 1990-2001. The facility was a tenant of a small retail building which adjoined a large supermarket. The supermarket and adjoining retail building were demolished and replaced with a different retail facility in 2005. The site is located in a densely developed commercial area of St. Charles County, Missouri.

Remediation Status: Site closed


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


Contaminant Media Concentration (ppb) Nondetect
Tetrachloroethene (PCE) groundwater 17,000 ppb
Tetrachloroethene (PCE) soil 424,000 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   12ft bgs
Plume Size:   Plume Length: 65ft
Plume Width: 50ft
Average Depth to Groundwater:   14.7ft

Lithology and Subsurface Geology

 
  Silty clay
Depth: 0.5-9ft bgs
8.5ft thick
 
  clay
Depth: 9-34ft bgs
25ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
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 completed VI pathway has been indentified
Has a vapor mitigation system been installed?
  No 
Additional VI Information:
  The treatment of the groundwater reduced the contaminants to levels safe for indoor air protection for any use of the site.

Remediation Scenario

Cleanup Goals:
  Groundwater: PCE = .005 mg/l (MCL)
Soil: PCE = 6 mg/kg

Technologies

In Situ Chemical Oxidation
 

Why the technology was selected:
Since the site was on a fast track for redevelopment, the remediation of the site had to be completed within 3 months. Based on this and the results of the site assessment, the consultant proposed to remediate the site by excavating and disposing the soils with high concentrations of PCE and treating the groundwater in the excavation with sodium permanganate (NaMnO4). In addition, NaMnO4, would be injected down gradient of the excavation to treat any extended plume and to provide a barrier against further migration.

Date implemented:
January 6, 2005

Final remediation design:
The initial action was to remove and stockpile the overburden material (0-10 ft bgs), which would later be used as backfill. At a depth of approximately 10 ft. bgs the zone of contamination was encountered. The excavation continued to depth of approximately 25 ft. bgs. No groundwater was present in the excavation upon completion, although the bottom of the pit was below groundwater levels measured and present in the surrounding monitoring wells. A garden sprayer was utilized to apply about 45.6 pounds of NaMnO4 to the bottom of the excavation and the walls below 10 ft. bgs. Large rock (6 to 8-inch in diameter) was then utilized to fill the first 6-feet of the excavation. This rock was used not only to stabilize the fill, but to allow groundwater, if any, to mix with the NaMnO4 for treatment. Clean overburden material was mixed with 1-inch minus rock and utilized to fill the excavation from 19 to 8 ft. bgs. The remainder of the overburden material was used to fill the excavation from 8ft. bgs. to the surface. While the backfill operation was being conducted, a Geoprobe® rig was used to inject NaMnO4 in four borings down gradient of the excavation. Approximately 6 pounds of NaMnO4 was injected in each of the borings in an interval from 10 to 24 ft. bgs.

Results to date:
Approximately 857 tons of the impacted soil were disposed of as special waste and the remaining 300 tons of impacted soil were disposed of as hazardous waste. Subsequent sampling of the groundwater over a 3 month period indicated that the PCE concentrations dropped from an initial level of 17 mg/L to 8.4 mg/L and remained stable. The treatment of the groundwater reduced the contaminants to levels safe for indoor air protection for any use of the site. Because the treatment did not remediate the site to levels considered safe for use of the groundwater as a water supply, an Activity and Use Limitation (AUL) prohibiting the use of the groundwater was required. The AUL was recorded with the St. Charles County Recorder of Deeds for the purposes of protecting public health. A Certification of Completion Letter for the site was issued by the Brownfields/Voluntary Cleanup Program (BVCP) on August 11, 2005.

Ex Situ Soil Removal
 

Why the technology was selected:
Since the site was on a fast track for redevelopment, the remediation of the site had to be completed within 3 months. Based on this and the results of the site assessment, the consultant proposed to remediate the site by excavating and disposing the soils with high concentrations of PCE and treating the groundwater in the excavation with sodium permanganate (NaMnO4). In addition, NaMnO4, would be injected down gradient of the excavation to treat any extended plume and to provide a barrier against further migration.

Date implemented:
January 6, 2005

Final remediation design:
The initial action was to remove and stockpile the overburden material (0-10 ft bgs), which would later be used as backfill. At a depth of approximately 10 ft. bgs the zone of contamination was encountered. The excavation continued to depth of approximately 25 ft. bgs. No groundwater was present in the excavation upon completion, although the bottom of the pit was below groundwater levels measured and present in the surrounding monitoring wells. A garden sprayer was utilized to apply about 45.6 pounds of NaMnO4 to the bottom of the excavation and the walls below 10 ft. bgs. Large rock (6 to 8-inch in diameter) was then utilized to fill the first 6-feet of the excavation. This rock was used not only to stabilize the fill, but to allow groundwater, if any, to mix with the NaMnO4 for treatment. Clean overburden material was mixed with 1-inch minus rock and utilized to fill the excavation from 19 to 8 ft. bgs. The remainder of the overburden material was used to fill the excavation from 8ft. bgs. to the surface. While the backfill operation was being conducted, a Geoprobe® rig was used to inject NaMnO4 in four borings down gradient of the excavation. Approximately 6 pounds of NaMnO4 was injected in each of the borings in an interval from 10 to 24 ft. bgs.

Results to date:
Approximately 857 tons of the impacted soil were disposed of as special waste and the remaining 300 tons of impacted soil were disposed of as hazardous waste. Subsequent sampling of the groundwater over a 3 month period indicated that the PCE concentrations dropped from an initial level of 17 mg/L to 8.4 mg/L and remained stable. The treatment of the groundwater reduced the contaminants to levels safe for indoor air protection for any use of the site. Because the treatment did not remediate the site to levels considered safe for use of the groundwater as a water supply, an Activity and Use Limitation (AUL) prohibiting the use of the groundwater was required. The AUL was recorded with the St. Charles County Recorder of Deeds for the purposes of protecting public health. A Certification of Completion Letter for the site was issued by the Brownfields/Voluntary Cleanup Program (BVCP) on August 11, 2005.

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  -Environmental Consulting Services-$33,299.01 -Soil Boring/Monitoring Well Installation-$12,899.25 -Laboratory Analysis-$13,249.00 -Equipment Rental/Lease/Purchase-$825.00 -Excavation-$50,343.92 -Disposal/Treatment-$50,786.78 -Site Restoration (Backfill, etc.)-$23,602.77 -Remediation Activities-$1,516.86 -Groundwater Monitoring-$304.00 -Other Costs (Permits, etc.)-$450.00 Grand Total = $187,276.59

Contacts

Scott Huckstep
Drycleaning Environmental Response Trust Fund
Missouri Department of Natural Resources
P.O. Box 176
Jefferson City, Missouri 65102-0176
(573) 522-1597
scott.huckstep@dnr.mo.gov