Remediation Status: Site closed

Why the technology was selected:
Monitored natural attenuation was the remedy selected for this site after completion of a contamination assessment in 1997. This was based on the low contaminant concentrations detected in groundwater and (at the time) the lack of significant contamination found in the unsaturated zone at the site. After approximately six years of monitoring and the detection of PCE in a downgradient monitoring well, soil samples were collected beneath the facility floor slab. PCE was detected in these soil samples, and the decision was made to actively remediate contaminated soil at the site. Soil vapor extraction was chosen as the soil remedial technology, because it is an effective technology for removing VOCs from permeable unsaturated sediments.

Next Steps:
A Site Rehabilitation Completion Order will be issued for the site.

Cost to Design and Implement:
$57,200 for all technologies

Why the technology was selected:
Monitored natural attenuation was the remedy selected for this site after completion of a contamination assessment in 1997. This was based on the low contaminant concentrations detected in groundwater and (at the time) the lack of significant contamination found in the unsaturated zone at the site. After approximately six years of monitoring and the detection of PCE in a downgradient monitoring well, soil samples were collected beneath the facility floor slab. PCE was detected in these soil samples, and the decision was made to actively remediate contaminated soil at the site. Soil vapor extraction was chosen as the soil remedial technology, because it is an effective technology for removing VOCs from permeable unsaturated sediments.

Date implemented:
February 3, 2005

Final remediation design:
Two lateral vapor extraction wells were installed at the site. Since drycleaning operations had ceased, one lateral was installed beneath the floor slab at the former location of the drycleaning machine. The other lateral was installed outside the service door of the facility. The laterals were constructed of 1-inch diameter Schedule 40 PVC with 0.020-inch slit. They were installed 28 inches below grade. A 3 HP rotary lobe blower was utilized. Off gas was treated with two 175 lb. G.A.C. units. The system was operated at 77 scfm with an applied vacuum of 28 - 30 inches w.c.

Results to date:
The SVE system was shut down on August 24, 2005. Although a negligible amount of VOCs (less than one pound) was recovered by the sytem, contaminant concentrations in groundwater dropped below cleanup target levels in June 2005 and remained below cleanup target levels for over a year. Low VOC recovery was likely due to excavation of contaminated soil during installation of SVE laterals.

Next Steps:
A Site Rehabilitation Completion Order will be issued for the site.

Cost to Design and Implement:
$57,200 for all technologies

Date implemented:
February 3, 2005

Final remediation design:
Two lateral vapor extraction wells were installed at the site. Since drycleaning operations had ceased, one lateral was installed beneath the floor slab at the former location of the drycleaning machine. The other lateral was installed outside the service door of the facility. The laterals were constructed of 1-inch diameter Schedule 40 PVC with 0.020-inch slit. They were installed 28 inches below grade. A 3 HP rotary lobe blower was utilized. Off gas was treated with two 175 lb. G.A.C. units. The system was operated at 77 scfm with an applied vacuum of 28 - 30 inches w.c.

Results to date:
The SVE system was shut down on August 24, 2005. Although a negligible amount of VOCs (less than one pound) was recovered by the sytem, contaminant concentrations in groundwater dropped below cleanup target levels in June 2005 and remained below cleanup target levels for over a year. Low VOC recovery was likely due to excavation of contaminated soil during installation of SVE laterals.

Next Steps:
A Site Rehabilitation Completion Order will be issued for the site.

Cost to Design and Implement:
$57,200 for all technologies