Remediation Status: In groundwater monitoring

Why the technology was selected:
DEQ identified the SVE system as a feasible method because of its potential to reduce and control the migration of chlorinated solvents in the unsaturated soil zone beneath the building and easy implementability. (IRAMs are just used to get something "done" at a site while it is being fully investigated/evaluated.)

Date implemented:
1998

Final remediation design:
The SVE system included 4 SVE wells, a vacuum blower and associated piping. A vapor extraction rate of 100 cubic feet per minute (ft3/min) was applied to the four SVE wells beginning in February 1998.

Results to date:
PCE concentrations in the recovered soil gas was as high as 2,700 ppm during initial operation, but quickly declined to approximately 70 ppm after several months of operation. The SVE system operated until October 1999 when it was decommissioned. Volatile organic compound (VOC) concentrations in the soil gas had declined to levels less than 5 ppm. During its operation, the SVE system removed approximately 640 pounds of VOCs from the soil above the water table in the vicinity of the outbuilding and from beneath the dry cleaner building. The SVE system was decommissioned in 2003.

Next Steps:
DEQ issued No Further Action remedial decision in December 2002. Monitoring and remediation systems removed in February 2003. DEQ is currently in negotiations with a prospective purchaser who desires to develop the proeprty for mixed use, including residential housing. Additional site investigation has been conducted to assess the need for engineering or other controls during site development.

Cost to Design and Implement:
$1,059,000(SVE and Groundwater extraction)

Why the technology was selected:
DEQ chose the groundwater extraction system because it provided a means to conduct mass removal and prevent the groundwater contamination from migrating toward a local water bodies. Evaluation of "innovative" technologies was done at the time, but not enough work had been done to recommend use at this site.

Date implemented:
1998

Final remediation design:
The groundwater IRM included two extraction wells (AMW-11 and AMW-16), an air stripper groundwater treatment system (GTS) with activated carbon secondary treatment, and associated piping and electrical lines to each of the extraction wells to the GTS. Treated groundwater was discharged to surface water via an on-site storm drain pursuant to discharge requirements speci-fied by DEQ. The system was brought on-line in February 1998. Groundwater extraction rates ranged from 10 to 25 gpm from each well.

Results to date:
In July 2001, DEQ chose to discontinue operation of the groundwater IRAM based on continued problems with scaling on the GTS and the findings of the beneficial water use evaluation, which indicated groundwater use for drinking water within the area was unlikely to occur in the future. Residual HVOC concentrations in groundwater at that time were below DEQ risk-based concentrations for vapor intrusion exposure pathway (most conservative cleanup goal besides drinking water). A quarterly groundwater monitoring program was implemented following system shut down to assess HVOC concentrations over time and further evaluate natural attenuation of HVOCs.

Next Steps:
DEQ issued No Further Action remedial decision in December 2002. Monitoring and remediation systems removed in February 2003. DEQ is currently in negotiations with a prospective purchaser who desires to develop the proeprty for mixed use, including residential housing. Additional site investigation has been conducted to assess the need for engineering or other controls during site development.

Cost to Design and Implement:
$1,059,000(SVE and Groundwater extraction)