Drycleaner Site Profiles

Shorty Cleaners, Stillwater, Minnesota

Description
Historical activity that resulted in contamination.

The site consists of a single story masonry building and adjacent parking lot. The site comprises approximately 13,000 square feet. The site is located in a residential/commercial area. Two dry cleaning machines are on property and PCE was the primary solvent used for the operation. The site is contaminated with both BTEX and chlorinated solvent.

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


Contaminant Media Concentration (ppb) Nondetect
Benzene groundwater 3.3 ppb
Benzene soil 4,000 ppb
sec-butylbenzene soil 3,700 ppb
cis-1,2-Dichloroethene groundwater 5,000 ppb
cis-1,2-Dichloroethene soil 6,100 ppb
ethylbenzene groundwater 280 ppb
ethylbenzene soil 62,000 ppb
n-butylbenzene soil 230,000 ppb
n-propylbenzene soil 150,000 ppb
Tetrachloroethene (PCE) groundwater 50,000 ppb
Tetrachloroethene (PCE) soil 1,200,000 ppb
p-isopropyltoluene soil 18,000 ppb
1,2,4-trimethylbenzene soil 95,000 ppb
1,3,5-trimethylbenzene soil 37,000 ppb
naphthalene groundwater 1,500 ppb
naphthalene soil 23,000 ppb
Trichloroethene (TCE) groundwater 5,500 ppb
Trichloroethene (TCE) soil 16,000 ppb
toluene groundwater 34 ppb
Vinyl Chloride groundwater 430 ppb
xylenes groundwater 94 ppb
xylenes soil 97 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:  
Plume Size:  
Average Depth to Groundwater:   11ft

Lithology and Subsurface Geology

 
  silty sand fill
Depth: 0-11ft bgs
11ft thick
 
  sand to silty sand
Depth: 11-20ft bgs
9ft thick
Conductivity: 3.15ft/day
Gradient: 0.318ft/ft
 
  sand to silty sand with clay layers, clay layers are 0.25 to 11 inch thick
Depth: 20-40ft bgs
20ft thick
Conductivity: 16.8ft/day
 
  gravelly sand to sand with gravel
Depth: 40-60ft bgs
20ft thick
 
  bedrock
Depth: 60-120ft bgs
60ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkDNAPL Present

Remediation Scenario

Cleanup Goals:
  Groundwater: Eliminate hot spot at MW-3.

Soil: Reach asymptotic removal rates of VOCs for 3 consecutive quarters.

Technologies

In Situ Chemical Oxidation
 

Why the technology was selected:
It is cost effective and it will also address BTEX impacts by delivering oxygen to the unsaturated zone to promote biodegradation.

Date implemented:
Chemical oxidation – pending as of August 2003

Next Steps:
Additional field work is underway to confirm/further define extent of ground water contamination. The consultant is preparing a work plan to implement in-situ chemical oxidation at the site using sodium or potassium permanganate injections. Additional soil and ground water monitoring will occur as part of this remedial action.

In Situ Monitored Natural Attenuation
 

Final remediation design:
Natural attenuation is being assessed through semi-annual groundwater monitoring.

Results to date:
Ground water monitoring has been conducted for several years. The data indicate that only one well is substantially impacted by PCE and its degradation products. Although the concentration of the degradation products has increased steadily over time, the concentration of PCE remains quite high. The PCE concentration in ground water decreased by 50% (6200 ug/l to 3000 ug/l) during operation of the SVE, but spiked up again (10,000 ug/l) after the SVE system was shut off

Next Steps:
Additional field work is underway to confirm/further define extent of ground water contamination. The consultant is preparing a work plan to implement in-situ chemical oxidation at the site using sodium or potassium permanganate injections. Additional soil and ground water monitoring will occur as part of this remedial action.

In Situ Soil Vapor Extraction
 

Why the technology was selected:
It is cost effective and it will also address BTEX impacts by delivering oxygen to the unsaturated zone to promote biodegradation.

Date implemented:
SVE - June 1998

Final remediation design:
The SVE system had 6 extraction points connected to a blower located on site. The piping for the system is buried 4 ft below grade. The soil vents were inserted through old soil boring locations in situ. The radius of influence was assumed to be 25 ft. The air flow was operated continuously with exhaust air flow typically around 125 scfm. System turned off after 24 months.

Results to date:
Ground water monitoring has been conducted for several years. The data indicate that only one well is substantially impacted by PCE and its degradation products. Although the concentration of the degradation products has increased steadily over time, the concentration of PCE remains quite high. The PCE concentration in ground water decreased by 50% (6200 ug/l to 3000 ug/l) during operation of the SVE, but spiked up again (10,000 ug/l) after the SVE system was shut off

Next Steps:
Additional field work is underway to confirm/further define extent of ground water contamination. The consultant is preparing a work plan to implement in-situ chemical oxidation at the site using sodium or potassium permanganate injections. Additional soil and ground water monitoring will occur as part of this remedial action.

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
 

Contacts

Amy Hadiaris, P.G.
Voluntary Investigation and Cleanup Program
Minnesota Pollution Control Agency
520 Lafayette Rd
Saint Paul, MN 55155-4194
651-296-8947
amy.hadiaris@pca.state.mn.us

Consultant:
Delta Environmental Consulting, Inc
2770 Cleveland Ave
Roseville, MN 55113
651-639-9449

Site Specific References

1. Shorty Cleaner Launderer Environmental Assessment – Phase 2. January 15, 1996. Prepared by Delta Environmental Consulting, Inc.
2. Addendum – Phase II Report, February 25, 1997, Delta
3. Environmental Assessment – Phase 3/Response Action Plan. December 5, 1997. Prepared by Delta Environmental Consulting, Inc.
4. SVE System Installation and Startup Report, August 13, 1998, Delta
5. Ground Water Monitoring and Remediation System Closure Report, May 3, 2000, Delta.
6. GW Monitoring Report for Shorty Cleaner Launderer Site. June 25, 2001. Prepared by Delta Env. Consulting, Inc.