Drycleaner Site Profiles

Paramount Cleaners, Florissant, Missouri

Description
Historical activity that resulted in contamination.

Paramount Cleaners was a former perchloroethylene (PCE) drycleaning facility that operated from 1993-2003. The facility was a tenant of the Flower Valley Shopping Center, which is located in a commercial and residential area in north St. Louis 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 760 ppb
Tetrachloroethene (PCE) soil 1,200 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   35ft bgs
Plume Size:  
Average Depth to Groundwater:   18.5ft

Lithology and Subsurface Geology

 
  Silt and clayey silt
Depth: 1-8ft bgs
7ft thick
Conductivity: 0.0001ft/day
 
  silty clay
Depth: 8.5-25.5ft bgs
17ft thick
 
  clay
Depth: 26-35ft bgs
9ft 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:
  A risk assessment was subsequently conducted of the site using Missouri Risk-Based Corrective Action Technical Guidance. The evaluation eliminated the drinking water pathway and the representative concentrations of PCE were below the residential levels for the remaining completed pathways including indoor inhalation.

Remediation Scenario

Cleanup Goals:
  The initial cleanup goal for the groundwater was 5 µg/l (MCL). During the course of the remediation work the department implemented its draft Missouri Risk-Based Corrective Action (MRBCA)Technical Guidance. Under this process the drinking water pathway was eliminated at the site and the following cleanup objectives were utilized:

Groundwater (indoor inhalation pathway from vapors for residential setting): PCE = 928 µg/l

Soil (indoor inhalation pathway from vapors for residential setting): PCE = 1,020 µg/kg



Technologies

In Situ Chemical Oxidation
 

Why the technology was selected:
The consultant considered the injection of several different chemical oxidation commercial products. Based upon an examination of costs, time of remediation and site specific conditions, the consultant determined the use of potassium permanganate was the most cost effective means of remediating the solvent contamination at the site.

Date implemented:
1st injection (pilot test) 19 May, 2003; 2nd injection 10-19 December, 2003; 3rd injection 13-16 December, 2004

Final remediation design:
The initial pilot test consisted of the injection of 150 pounds of KMnO4 at four direct-push points in the vicinity of two monitoring wells (MW-3 and MW-5) to determine if this method would achieve the desired results as well as to determine the optimal amount of KMnO4 required to be injected on the remainder of the site. Subsequent sampling of the groundwater indicated that the initial results of the pilot test were successful. PCE concentrations in the source area (MW-3) decreased by more than 89% after application and PCE concentrations in the down gradient well (MW-5) were reduced to below the laboratory reporting limit (5µg/l). However, as expected the PCE concentrations in the source area did rebound through the course of the pilot study. The second event consisted of the injection of 1,450 pounds of KMnO4 at 29 additional points. As with the previous sampling events, the PCE concentrations declined significantly after this round of injections but rebounded. It was believed that the contaminant mass beneath the floor of the facility was substantially more than anticipated. It was determined that an additional injection event be conducted. During the third event, a total 1,200 pounds of KMnO4 were injected at four points around the source area, two near MW-1 and two near the building. Post injection sampling indicated that the PCE concentrations in the source area monitoring well (MW-3), decreased significantly, as PCE was not detected in the sample obtained from this well. PCE concentrations in several other wells (MW-1 and MW-4) slightly exceeded the original cleanup target level of 5 µg/L.

Results to date:
A fourth injection event was originally proposed to further reduce the PCE levels. However, at that time the department released its draft Missouri Risk-Based Corrective Action Technical Guidance document. A risk assessment was subsequently conducted of the site using this document. The evaluation eliminated the drinking water pathway and the representative concentrations of PCE were below the residential levels for the remaining completed pathways. The department therefore issued a Certification of Completion letter for unrestricted use of the site on June 9, 2005.

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  -Environmental Consulting Services = $40,557.59 -Soil Boring/Monitoring Well Installation = $11,231.50 -Laboratory Analysis = $14,622.00 -Equipment Rental/Lease/Purchase = $200.00 -Disposal/Treatment = $1,440.00 -Remediation Activities = $36,463.89 -Groundwater Monitoring = $3,055.00 -Other Costs (Permits, etc.) = $1,980.00 Grand Total = $109,549.98

Contacts

Scott Huckstep
Drycleaning Environmental Response Trust Fund
Missouri Department of Natural Resources
P.O. Box 176
Jefferson City, MO 65102-0176
(573)526-1597
scott.huckstep@dnr.mo.gov