Remediation Status: In groundwater monitoring

Why the technology was selected:
Off-site incineration was chosen given the listed waste nature of the soil and concentrations above the LDR/UTS. On-site treatment was not an option given the location of the site (downtown Klamath Falls, nearby daycare, air permitting issues, etc.).

Date implemented:
June 1995

Final remediation design:
Soils containing more than 5.6 mg/kg (the RCRA Universal Treatment Standard for PCE-contaminated soil) were sent off-site as "extremely hazardous" and incinerated. Soils with 0.3-5.6 mg/kg were sent off-site as "hazardous" for landfill disposal (0.3 mg/kg derived from Oregon's conservative health-based levels).

Results to date:
Contractors removed approximately 2,000 tons of contaminated soil containing PCE concentrations exceeding 0.3 mg/kg. Groundwater PCE concentrations have decreased since the 1980s. Peak concentrations decreased from about 13,400 µg/L in 1989 to the most recently measured level (January 1998) of less than 200 µg/L. Some monitoring wells have not shown any significant decrease with time, however. Beneficial water-use analysis and fate-and-transport modeling suggest that current and reasonably likely beneficial groundwater uses in the local area are not threatened by the contamination. Contractors believe that dissolved or residual PCE DNAPL is unlikely to migrate to the deeper basalt aquifer, which is used for drinking water.

Next Steps:
Uncertainties associated with fate-and-transport modeling are leading contractors to conduct periodic monitoring of sump water and selected groundwater monitoring wells in order to assess contaminant concentrations and confirm natural attenuation processes. Baseline human health risk assessments have identified unacceptable levels of contaminants in the indoor air in two nearby buildings. While vapor intrusion has decreased somewhat, additional data is needed, given the uncertainty posed by large building-specific variations in basement construction, ventilation characteristics, and the presence of other contaminants in sump water, such as 1,1-DCE. A pilot study will be implemented to reduce vapor concentrations, and periodic monitoring will be conducted to better characterize the risks.

Cost to Design and Implement:
$1.2 million (soil removal)

Why the technology was selected:
Off-site incineration was chosen given the listed waste nature of the soil and concentrations above the LDR/UTS. On-site treatment was not an option given the location of the site (downtown Klamath Falls, nearby daycare, air permitting issues, etc.).

Date implemented:
June 1995

Final remediation design:
Soils containing more than 5.6 mg/kg (the RCRA Universal Treatment Standard for PCE-contaminated soil) were sent off-site as "extremely hazardous" and incinerated. Soils with 0.3-5.6 mg/kg were sent off-site as "hazardous" for landfill disposal (0.3 mg/kg derived from Oregon's conservative health-based levels).

Results to date:
Contractors removed approximately 2,000 tons of contaminated soil containing PCE concentrations exceeding 0.3 mg/kg. Groundwater PCE concentrations have decreased since the 1980s. Peak concentrations decreased from about 13,400 µg/L in 1989 to the most recently measured level (January 1998) of less than 200 µg/L. Some monitoring wells have not shown any significant decrease with time, however. Beneficial water-use analysis and fate-and-transport modeling suggest that current and reasonably likely beneficial groundwater uses in the local area are not threatened by the contamination. Contractors believe that dissolved or residual PCE DNAPL is unlikely to migrate to the deeper basalt aquifer, which is used for drinking water.

Next Steps:
Uncertainties associated with fate-and-transport modeling are leading contractors to conduct periodic monitoring of sump water and selected groundwater monitoring wells in order to assess contaminant concentrations and confirm natural attenuation processes. Baseline human health risk assessments have identified unacceptable levels of contaminants in the indoor air in two nearby buildings. While vapor intrusion has decreased somewhat, additional data is needed, given the uncertainty posed by large building-specific variations in basement construction, ventilation characteristics, and the presence of other contaminants in sump water, such as 1,1-DCE. A pilot study will be implemented to reduce vapor concentrations, and periodic monitoring will be conducted to better characterize the risks.

Cost to Design and Implement:
$1.2 million (soil removal)