Drycleaner Site Profiles

Oxboro Cleaners, South Bloomington, Minnesota

Description
Historical activity that resulted in contamination.

The site is a former dry cleaning operation (began operation in 1956) and a photo finishing facility. There were several USTs at the site associated with both operations. The site is being redeveloped for commercial and residential land use.

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


Contaminant Media Concentration (ppb) Nondetect
tert butylbenzene groundwater 27 ppb
1,2-Dichloroethane groundwater 3.1 ppb
1,1-Dichloroethene groundwater 13 ppb
n-butylbenzene groundwater 5.8 ppb
n-propylbenzene groundwater 29 ppb
Tetrachloroethene (PCE) groundwater 37 ppb
Tetrachloroethene (PCE) soil 1,000 ppb
p-isopropyltoluene groundwater 13 ppb
naphthalene groundwater 2.2 ppb
Trichloroethene (TCE) groundwater 58 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:  
Plume Size:  
Average Depth to Groundwater:   40ft

Lithology and Subsurface Geology

 
  Gravel/Silt Tan/Black
Depth: 0-2ft bgs
2ft thick
 
  Sand/Gravel Dark Red
Depth: 2-5ft bgs
3ft thick
 
  Sand Brown
Depth: 5-35ft bgs
30ft thick
 
  Sand/Cobbles Dark Brown
Depth: 35-40ft bgs
5ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
DNAPL Present

Remediation Scenario

Cleanup Goals:
 

Technologies

In Situ Soil Vapor Extraction
 

Date implemented:
October 10, 1997

Final remediation design:
System operation was checked weekly during the first three weeks of operation and monthly thereafter. During each site visit, the vacuum of each soil venting well was measured at the manifold and at the wellhead; the vacuum of the three monitoring points, nearly monitoring wells, and the blower intake were measured. Also, the flow rates of the soil venting wells and discharge were measured; and the total organic vapor (TOV) concentration of each soil venting well and the discharge was measured. The system was designed so that individual soil venting wells could be isolated from the system to alleviate potential stagnation zones. It was noted that the TOV concentration increased to over 100 ppm in SVE lines that were closed off and there was no flow. The TOV concentration at the well head was indicative of concentrations observed when the lines had airflow. This indicates that maybe the PVC or glue was responsible for the elevated TOV concentrations in stagnant lines. Therefore the concentrations detected in the stagnant lines are considered anomalous.

Results to date:
Soil: The result show that the PCE concentration of the discharge decreased from 160mg/m3 on October 20, 1997 to 2.3mg/m3 on May 8, 1998. Cis-1,2dichloroethene (DCE) was detected at a concentration of 7.2mg/m3 in the October 20, 1998 sample, but was not detected in the remaining samples. The PCE air emissions decreased from 17,532

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  $182,906.63

Lessons Learned

1. The SVE worked well on reducing the PCE at this site. CLeanup criteria were met within a couple years.
2. A clay lens at 10 ft. bgs seemed to hold most of the PCE in place which was helpful in the remediation process.

Contacts

Jonathan Smith, Staff TA
MPCA
525 Lake Avenue, #400
Duluth, MN 55802
218-723-4958
jonathan.smith@pca.state.mn.us