Description
Bethel removed contaminated soil at the FAA Air-Route Surveillance Radar (ARSR) station located atop Mica Peak, in eastern Washington. The primary objective of this project was to remove petroleum-contaminated soil that resulted from two unlabeled, leaking drums found abandoned at the ARSR and to demonstrate the site is in compliance with the Washington Department of Ecology (Ecology) Models Toxics Control Act (MTCA) cleanup standards for unrestricted land use.
To meet the objective of removing the petroleum-contaminated soil, Bethel vacuumed and excavated soil approximately 9 feet by 14 feet in area and four feet deep from the site of contamination and disposed the soil at a permitted landfill. A vacuum truck was used in addition to an excavator due to numerous buried utility lines that ran alongside the area to be remediated. Soil removal was guided by field screening with a photoionization detector (PID), which indicated that contaminated soil was completely removed.
After soil removal, Bethel collected five confirmation soil samples from the limits of the excavation that were tested for diesel-range organics (DRO); benzene, toluene, ethylbenzene, xylenes (BTEX); and polycyclic aromatic hydrocarbons (PAHs). The resulting excavation was backfilled with surplus fill material that was available at the site.
Confirmation samples showed that one sample had a DRO concentration of 5,400 milligrams per kilogram (mg/kg), which exceeds the MTCA cleanup standard of 2,000 mg/kg. All other samples and analytes were in compliance with MTCA standards. Bethel maintained that the DRO concentration measured in the exceedance sample was not representative of in situ soil due to lack of hydrocarbon odor, low associated PID reading, and that the result was potentially a laboratory error. The FAA and Ecology agreed with this conclusion and the site was granted regulatory closure with no further remedial action be required.
Client
Federal Aviation Administration
Location
Spokane, Washington
Period of Performance
5/2015 - 4/2017
Contract Value
$36k
Contract Number
DTFAAL-10-D-0003, TO 0031
Work Performed
Work Plan Preparation and Approval
Soil Removal and Disposal
High-Volume Vacuum Excavation Methods
Field-Screening and Soil Sampling
Reporting
Regulatory Closure