Drycleaner Site Profiles

Westgate Cleaners, Salem, Oregon

Description
Historical activity that resulted in contamination.

Westgate cleaners was located in a commercial shopping center. Drycleaning businesses have operated at the same location since 1963 and have used PCE in their cleaning process. PCE solvent is thought to have entered the subsurface from past releases to the sanitary sewer system. The shopping center is currently undergoing redevelopment, and many of the buildings have been demolished, including the former drycleaner building. The demolition of the drycleaner building provided a good opportunity for soil removal activities.

Remediation Status: In active remediation


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


Contaminant Media Concentration (ppb) Nondetect
chloroform groundwater 11.4 ppb
cis-1,2-Dichloroethene groundwater 70.8 ppb
methylene chloride groundwater ND
n-propylbenzene groundwater 9.9 ppb
Tetrachloroethene (PCE) groundwater 65,000 ppb
Tetrachloroethene (PCE) soil 21,000 ppb
1,1,1-Trichloroethane groundwater 0.24 ppb
Trichloroethene (TCE) groundwater 302 ppb
Trichloroethene (TCE) soil 200 ppb
toluene groundwater 0.45 ppb
trans-1,2-Dichloroethene groundwater 1.1 ppb
Vinyl Chloride groundwater 1.6 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   25ft bgs
Plume Size:   Plume Length: 600ft
Plume Width: 300ft
Plume Thickness: 20ft
Average Depth to Groundwater:   15ft

Lithology and Subsurface Geology

 
  Brown clayey silt
Depth: 0-15ft bgs
15ft thick
 
  Silty, very fine sand
Depth: 15-18ft bgs
3ft thick
 
  Medium-to-coarse sand with gravel and pebbles
Depth: 18-30ft bgs
12ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
DNAPL Present

Remediation Scenario

Cleanup Goals:
  Soil: DEQ's risk based concentrations for vapor intrusion potential:
PCE - 1.5 mg/kg
TCE - 0.094 mg/kg
t-DCE - 230 mg/kg
Vinyl chloride - 2.0 mg/kg

Technologies

In Situ Monitored Natural Attenuation
 

Why the technology was selected:
Monitored Natural Attenuation was chosen as the most appropriate solution for contaminants in groundwater.

Final remediation design:
Monitor attenuation of contaminant concentrations in groundwater.

Results to date:
Natural attenuation processes, controlled and consistently monitored, will be relied upon to degrade groundwater contaminants.

Next Steps:
Following 6 months of soil treatment, some soil will be re-used on the site for development, and the remainder will be disposed of at the appropriate facility. New wells will be installed once the shopping center redevelopment is completed. The groundwater will be monitored on a semi-annual basis to make sure the contaminants are degrading and to determine when appropriate stability/risk levels are achieved for site closure.

Cost to Design and Implement:
$80,000 for all technologies

Ex Situ Soil Removal
 

Why the technology was selected:
Excavation of contaminated soils above vapor intrusion risk levels was chosen because 1)the shopping center was undergoing redevelopment, so soils were easily accessible and 2)vapor intrusion of chlorinated solvents into buildings on site was the pathway of concern.

Date implemented:
October 2005

Final remediation design:
Excavate, stockpile, treat and dispose of two source areas of contaminated soil to a depth of 6-16 feet bgs. One area is approximately 200 square feet and the other at 97 square feet.

Results to date:
Approximately 200 tons of source area contaminated soils above vapor intrustion risk levels were excavated and stockpiled onsite. Approximately 30 tons were at levels for subtitle D landfill disposal. The remaining 170 tons of soil are being treated onsite using vapor extraction for approximately 6 months until levels are within residential guidelines.

Next Steps:
Following 6 months of soil treatment, some soil will be re-used on the site for development, and the remainder will be disposed of at the appropriate facility. New wells will be installed once the shopping center redevelopment is completed. The groundwater will be monitored on a semi-annual basis to make sure the contaminants are degrading and to determine when appropriate stability/risk levels are achieved for site closure.

Cost to Design and Implement:
$80,000 for all technologies

Costs

Cost for Assessment:
  $80,000
Cost for Operation and Maintenance:
  $16,000 for O&M of onsite soil treatment.
Total Costs for Cleanup:
 

Lessons Learned

1. You never know until you start digging how much soil will need to be removed and what the disposal/treatment costs will entail. Anything prior is only an estimate and could be an underestimate.

Contacts

Nancy Sawka
Oregon DEQ
750 Front St. NE, Suite 120
Salem, OR 97301
503-378-8240
sawka.nancy@deq.state.or.us