Shorty Cleaners, Stillwater, Minnesota

State Coalition for Remediation of Drycleaners Site Profiles

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)
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

Groundwater

Sediments

Soil

DNAPL 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

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.

Costs

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

Contacts

Groundwater Atlas
https://www.pca.state.mn.us/data/minnesota-groundwater-contamination-atlas

What's in My Neighborhood
https://www.pca.state.mn.us/data/whats-my-neighborhood

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.

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

State Coalition for Remediation of Drycleaners Site Profiles