Drycleaner Site Profiles

Bowen Cleaners, Greenville, North Carolina

Description
Historical activity that resulted in contamination.

Stand-alone 3,000 ft2 building currently used as a drop-off store. Active PCE drycleaner operated between 1988 to 2001 using 1 50# Dry-to-Dry machine. Surrounding property is retail and flanked by shopping centers.

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
cis-1,2-Dichloroethene soil
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
Trichloroethene (TCE) groundwater
Trichloroethene (TCE) soil
Vinyl Chloride groundwater
Vinyl Chloride soil

Site Hydrology

Deepest Significant Groundwater Contamination:  
Plume Size:   Plume Length: 230ft
Plume Width: 170ft
Average Depth to Groundwater:   4.6ft

Lithology and Subsurface Geology

 
  Dark gray-brown SILTY CLAY
Depth: 0-8ft bgs
8ft thick
Conductivity: 0.28ft/day
Gradient: 0.03ft/ft
 
  Orange-gray, stiff CLAY
Depth: 8-15ft bgs
7ft thick
 
  Gray, fine-medium SILTY SAND
Depth: 15-18ft bgs
3ft thick

Pathways and DNAPL Presence

Groundwater
Sediments
Soil
checkPresumptive Evidence of DNAPL

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  No
Has a vapor mitigation system been installed?
   

Remediation Scenario

Cleanup Goals:
 
Remedy Level:
  Interim Action

Technologies

In Situ Biostimulation
 

Why the technology was selected:
High concentrations in soil along the footing of the building complicated excavation. Injection was the best application technology for the location of contamination.

Date implemented:
2009, April

Final remediation design:
2,800 pounds of EHC by Adventus, micron sized zero valent iron and carbon mixed water and injected into the soil source area and in the vicinity of the highest groundwater contamination outside of the soil contamination. 15 points spaced 12 feet apart. 49 gallons/point at 3-4 gpm < 300 PSI. Treatment zone from 20 to 6 feet bgs bottom-up at 1 foot intervals.

Results to date:
2011, May Monitoring well SA1 is located outside of the soil source contamination. [PCE] dropped from 8 ppm to 0.0713 ppm. Daughter products increased minimally. Monitoring well SA2 is located in the area of highest soil contamination. [PCE] went from 25 ppm down to 7 ppm in 1 year with significant increase in daughter products. 1 year later and [PCE] has bounced back to 22 ppm but daughter products concentrations have continued to decrease.

Next Steps:
Continued monitoring of contamination for stability. Possible application of vapor extraction to remove soil contamination.

Cost to Design and Implement:
$32,000 EHC $2.25/pound, $6,300 total Injection $10,291

In Situ Zero Valent Iron
 

Why the technology was selected:
High concentrations in soil along the footing of the building complicated excavation. Injection was the best application technology for the location of contamination.

Date implemented:
2009, April

Final remediation design:
2,800 pounds of EHC by Adventus, micron sized zero valent iron and carbon mixed water and injected into the soil source area and in the vicinity of the highest groundwater contamination outside of the soil contamination. 15 points spaced 12 feet apart. 49 gallons/point at 3-4 gpm < 300 PSI. Treatment zone from 20 to 6 feet bgs bottom-up at 1 foot intervals.

Results to date:
2011, May Monitoring well SA1 is located outside of the soil source contamination. [PCE] dropped from 8 ppm to 0.0713 ppm. Daughter products increased minimally. Monitoring well SA2 is located in the area of highest soil contamination. [PCE] went from 25 ppm down to 7 ppm in 1 year with significant increase in daughter products. 1 year later and [PCE] has bounced back to 22 ppm but daughter products concentrations have continued to decrease.

Next Steps:
Continued monitoring of contamination for stability. Possible application of vapor extraction to remove soil contamination.

Cost to Design and Implement:
$32,000 EHC $2.25/pound, $6,300 total Injection $10,291

Costs

Cost for Assessment:
  $63,000
Groundwater/soil contamination delineation.
Cost for Operation and Maintenance:
  $40,000 Installation of additional monitoring wells. Downhole water quality data recordders. 1 year monitoring and sampling. Analysis to include analysis for chlorinateds, natural attenuation parameters, fatty acid analysis.
Total Costs for Cleanup:
  $103, 000

Lessons Learned

After 2 years of sampling groundwater PCE concentrations have been significantly reduced outside of the area of soil contamination. Overlying soil contamination is contributing PCE contamination to groundwater in the source area. Reduction took longer than anticipated.

Contacts

Scott Stupak
Project Manager
Scott.Stupak@ncdenr.gov

Site Specific References

October 6, 2009 EHC Pilot Test Report
February 17, 2010 Post Injection Report
November 15, 2011 Final Groundwater Monitoring Report