Remediation Status: Site closed

Why the technology was selected:
Innovative technologies like Hydrogen Release Compound (HRC) were not readily available when the remediation was first conducted at this site. The AS/SVE appeared to be a feasible, cost effective method to reduce concentration levels. Remedy implemented by owner prior to entering Oregon Dry Cleaner Program.

Date implemented:
SVE/AS began in late 1994. System taken off-line in July 2000.

Final remediation design:
The AS system consists of 6 sparging wells screened to a depth of 25-30 ft. bgs., a compressor, piping and associated controls and removes halogenated VOCs from saturated soils and groundwater. All remediation machinery is housed in an on-site concrete slab (6 ft. by 8 ft.) surrounded by a chain-link fence.

Results to date:
Groundwater monitoring and sampling events conducted by contractors indicate that the PCE groundwater plume is stable. Residual VOC concentrations below RBCs for vapor intrusion. The contractor estimated that the remediation system removed approximately 388 lbs. of VOCs during 5 years of operation. The removal of VOCs leveled off after approximately 2 years of operation. A general decrease in groundwater VOC concentrations was observed with the initiation of AS/SVE operation. The most significant change in PCE concentration occurred in the first year: a decrease of PCE from 1200 µg/L to 542 µg/L. Concentrations of PCE breakdown products increased: TCE was sampled at 179 µg/L, cis-1,2-DCE was found at 314 µg/L, and trans-1,2-DCE was found at 22.8 µg/L. Rebounding PCE concentrations, though, were observed in other monitoring well locations.

Next Steps:
DEQ issued No Further Action decision for the site in January 2004 based on the results of the baseline risk assessment that showed that existing contamination did not pose an unacceptable risk to human health and the environment.

Cost to Design and Implement:
Estimated design and implementation costs for AS & SVE were $300K. Much of the work completed prior to entering Oregon Dry Cleaner Program.

Why the technology was selected:
Innovative technologies like Hydrogen Release Compound (HRC) were not readily available when the remediation was first conducted at this site. The AS/SVE appeared to be a feasible, cost effective method to reduce concentration levels. Remedy implemented by owner prior to entering Oregon Dry Cleaner Program.

Date implemented:
SVE/AS began in late 1994. VOC concentrations in SVE system at non-detect by early 1998. System taken off-line in July 2000.

Final remediation design:
Contractors installed horizontal SVE piping installed along the storm drain east of the facility (4-7 ft. bgs) and a four-leg horizontal SVE installed in the trenching for the AS system piping (2-5 ft. bgs.). The SVE operates with a blower pulling a vacuum of 3-6 in. of water on an airflow of 4,500 ft/min. All remediation machinery is housed in an on-site concrete slab (6 ft. by 8 ft.) surrounded by a chain-link fence.

Results to date:
Groundwater monitoring and sampling events conducted by contractors indicate that the PCE groundwater plume is stable. Residual VOC concentrations below RBCs for vapor intrusion. The contractor estimated that the remediation system removed approximately 388 lbs. of VOCs during 5 years of operation. The removal of VOCs leveled off after approximately 2 years of operation. A general decrease in groundwater VOC concentrations was observed with the initiation of AS/SVE operation. The most significant change in PCE concentration occurred in the first year: a decrease of PCE from 1200 µg/L to 542 µg/L. Concentrations of PCE breakdown products increased: TCE was sampled at 179 µg/L, cis-1,2-DCE was found at 314 µg/L, and trans-1,2-DCE was found at 22.8 µg/L. Rebounding PCE concentrations, though, were observed in other monitoring well locations.

Next Steps:
DEQ issued No Further Action decision for the site in January 2004 based on the results of the baseline risk assessment that showed that existing contamination did not pose an unacceptable risk to human health and the environment.

Cost to Design and Implement:
Estimated design and implementation costs for AS & SVE were $300K. Much of the work completed prior to entering Oregon Dry Cleaner Program.