Drycleaner Site Profiles

Schloff Chemicals and Supply Company, Inc., Saint Louis Park, Minnesota

Description
Historical activity that resulted in contamination.

This site is located in a commercial/industrial area. The facility supplied products to the dry cleaning and laundry industries, including cleaning solvents. There were two reported spills of PCE at the site, one in 1988 and one in 1989. The spills occurred at fill pipes accessed by the railroad spur and the truck transport. PCE contamination has been found in the soil, groundwater and surface water surrounding the facility at very high concentrations (…). It appears although there are two aquifers present at the site, only the upper groundwater aquifer is impacted, not the lower. This site was remediated under the Superfund program.

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


Contaminant Media Concentration (ppb) Nondetect
Tetrachloroethene (PCE) groundwater 7,800 ppb
Trichloroethene (TCE) groundwater 240 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:  
Plume Size:  
Average Depth to Groundwater:   10ft

Lithology and Subsurface Geology

 
  fine to coarse-grained sand
Depth: 0-27ft bgs
27ft thick
Conductivity: 13ft/day
Gradient: 0.0045ft/ft
 
  bedrock
Depth: 27-75ft bgs
48ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
Soil
DNAPL Present

Remediation Scenario

Cleanup Goals:
 

Technologies

Ex Situ Pump and Treat
 

Why the technology was selected:
These technologies were selected because they had not been used in Minnesota previously.

Date implemented:
September 1994

Final remediation design:
The UVB technology is an in-situ treatment for groundwater developed in Germany. It uses a combination of physical and biological processes. It creates a circulation cell that transports the dissolved mobile phase and residual mobile phase hydrocarbons to a central well casing for treatment. The treatment is primarily air stripping, secondarily bioremediation, for light and middle range fraction hydrocarbons. Two UVB wells were installed. The groundwater enters the remediation well through the lower screen section. After the GW has been oxygenated and stripped of VOCs, it is released through the upper screen. In the surrounding area of the remediation well, the induced flow will be from top of the aquifer to the bottom of the aquifer. 4 m3/h of water are being pumped into the UVB-200-1 reactor and 2 m3/h are being pumped back into the two UVB-200-2 stripping reactors. Thus, the stripping efficiency is 90 to 99% effective.

Other technologies used:
UVB -- in situ

In Situ Other
 

Why the technology was selected:
These technologies were selected because they had not been used in Minnesota previously.

Date implemented:
September 1994

Final remediation design:
The UVB technology is an in-situ treatment for groundwater developed in Germany. It uses a combination of physical and biological processes. It creates a circulation cell that transports the dissolved mobile phase and residual mobile phase hydrocarbons to a central well casing for treatment. The treatment is primarily air stripping, secondarily bioremediation, for light and middle range fraction hydrocarbons. Two UVB wells were installed. The groundwater enters the remediation well through the lower screen section. After the GW has been oxygenated and stripped of VOCs, it is released through the upper screen. In the surrounding area of the remediation well, the induced flow will be from top of the aquifer to the bottom of the aquifer. 4 m3/h of water are being pumped into the UVB-200-1 reactor and 2 m3/h are being pumped back into the two UVB-200-2 stripping reactors. Thus, the stripping efficiency is 90 to 99% effective.

Other technologies used:
UVB -- in situ

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  (as of 1999) $773,716

Lessons Learned

1. UVB technology had not been used in MN prior to this application. The contractor identified several MN specific modifications that facilitate the well installation.

2. The system was operated intermittently between December 1995 and June 1996 as numerous problems, including scaling, mechanical failures, and rewiring, surfaced. This type of system appears to require quite a bit of maintenance.

Contacts

Lifeng Guo, Staff TA
MPCA
520 Lafayette Rd.
Saint Paul, MN 55155-4194
651-296-8112