Drycleaner Site Profiles

Plaza Cleaners (former), Sweet Home, Oregon

Description
Historical activity that resulted in contamination.

Plaza cleaners operated from 1971 to 2001. The site is located in a commercial area adjacent to residential. The cleaners used PCE as it's solvent. No known discharges or spills were reported. The source of contamination appears to be from the location of the sewer line and "out the back door", either from disposal or storage of PCE containing materials. Nearby receptors include future commercial (vapor intrusion) on site, as well as downgradient use of groundwater for irrigation and domestic uses. Before investigation and cleanup activities were initiated, the building had been removed, leaving just a concrete slab. There was a lot of room to work, and no real time constraints on the cleanup work.

Remediation Status: In groundwater monitoring


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


Contaminant Media Concentration (ppb) Nondetect
cis-1,2-Dichloroethene groundwater
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
Trichloroethene (TCE) groundwater
Trichloroethene (TCE) soil

Site Hydrology

Deepest Significant Groundwater Contamination:   55ft bgs
Plume Size:  
Average Depth to Groundwater:   10ft

Lithology and Subsurface Geology

 
  silt with sand and gravel layers
Depth: 0-10ft bgs
10ft thick
Conductivity: 1ft/day
 
  clay and silt
Depth: 10-16ft bgs
6ft thick
 
  sand and gravel
Depth: 16-55ft bgs
39ft thick

Pathways and DNAPL Presence

Groundwater
Sediments
Soil
checkPresumptive Evidence of DNAPL

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:
  Undetermined
Has a vapor mitigation system been installed?
  No 
Additional VI Information:
  Further asssessment of the VI pathway is needed before the site can be considered for closure.

Remediation Scenario

Cleanup Goals:
  To remove the source and treat on-site highly concentrated groundwater over a short term (<5 years)in order to reduce concentrations to below risk based concentrations for vapor intrusion on-site, as well as reduce the threat of continued off-site migration toward downgradient groundwater users.
Remedy Level:
  Interim Action

Technologies

In Situ Bioremediation
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Other technologies used:
Carbstrate (dextrose) was used as the primary electron donor. Hydrolized ethyl lactate was later used. Both substrates were added to water extracted from downgradient wells and reinjected in and up gradient of the source area in a recirculating system. Ethyl lactate was later injected into the well network as slug injections.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

In Situ Biostimulation
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Other technologies used:
Carbstrate (dextrose) was used as the primary electron donor. Hydrolized ethyl lactate was later used. Both substrates were added to water extracted from downgradient wells and reinjected in and up gradient of the source area in a recirculating system. Ethyl lactate was later injected into the well network as slug injections.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

In Situ In Situ Flushing
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Other technologies used:
Carbstrate (dextrose) was used as the primary electron donor. Hydrolized ethyl lactate was later used. Both substrates were added to water extracted from downgradient wells and reinjected in and up gradient of the source area in a recirculating system. Ethyl lactate was later injected into the well network as slug injections.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

Ex Situ Carbon Adsorption
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

Ex Situ Soil Vapor Extraction
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

Ex Situ Soil Removal
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

In Situ Other
 

Why the technology was selected:
Limited excavation of source material was selected because of ease of access (building had been removed and site was very accessible. There was space to treat excavated soil on-site and time was not a significant factor for the soil treatment. Recirculating groundwater with electron donor amendments was elected as a proven method to greatly reduce contaminated mass in groundwater near the source zone quickly. O&M costs are relatively low.

Date implemented:
8/2006

Final remediation design:
A vapor intrusion assessment (soil gas sampling) is needed, along with a risk screening, to determine if any additinoal cleanup (final remedy) is needed. It is likely that no additional active cleanup will be required at this site.

Results to date:
250 cubic yards of soil contaminated with PCE were excavated and treated. Groundwater concentrations of PCE and TCE were reduced by approximately 98%, from 2,700 ug/L to 35 ug/L

Next Steps:
A vapor intrusion assessment is needed to determine if any further cleanup (or engineering/institutional controls) may be needed prior to closure.

Cost to Design and Implement:
$197,000 for all technologies

Costs

Cost for Assessment:
  $34,000
Cost for Operation and Maintenance:
  $25,000/year for 2.8 years
Total Costs for Cleanup:
  $301,000

Lessons Learned

The fact that the building had been removed, there was good site access for excavation and on-site treatment of soil, and there were few time constraints on the work made this project very cost effective, and the source of the contamination could be remediated quickly.

Limited soil removal remains a very cost effecitve technology.

Bioremediation using a recirculating (injection/extraction) approach increases the flow through the contaminated aquifer, helping to desorb and remove more contaminant mass in less time.

Contacts

Donald Hanson, RG
Oregon Department of Environmental Quality
165 E. 7th Avenue, Suite 100
Eugene, OR 97401
(541) 687-7349
hanson.don@deq.state.or.us

Site Specific References

Please see the Oregon DEQ Environmental Cleanup Site Information database page for this site, which includes copies of key reports:
http://www.deq.state.or.us/Webdocs/Forms/Output/FPController.ashx?SourceId=3244&SourceIdType=11