Background
During routine maintenance work at a natural gas compressor station, facility staff discovered two (2) large concrete tanks beneath a parking lot. The tanks were not identified on any facility drawings and were not known to be present at the site. Oil contained in the tanks was found to contain PCBs at levels exceeding the TSCA standard of 50 mg/kg. Three (3) underground lines were found connected to the tanks.
Tank and Soil Removal
At the request of the client, AGES oversaw an emergency response action to excavate the tanks and the adjoining lines. Appropriate site safety, and erosion and sediment control measures were established prior to field work. The tanks were quickly removed and disposed of as TSCA waste. Excavated soils were screened with immunoassay test kits and found to be non-TSCA. Laboratory results confirmed the screening results. By field screening and segregating wastes, AGES was able to reduce the cost for waste disposal by an order of magnitude.
Two (2) of the adjoining lines were found to dead-end near the tanks; both lines were excavated. The third line extended to a septic system which discharged several feet from a nearby creek. Near the creek, AGES staff implemented strict erosion and sediment control measures to prevent migration of water within the excavation to the creek. AGES also sampled the creek and confirmed that PCBs had not reached the creek. The site was then restored to its original condition.
Throughout the project, AGES was in constant contact with the client, the USEPA and the Army Corps of Engineers regarding the project status and field work schedule. The USEPA was very complimentary regarding AGES’ handling of the project and the excellent communications throughout the field work.
Special Project Features
1.) By using the immunoassay test kits to screen soil for PCBs, the volume of excavated soil was limited, which reduced waste disposal costs.
2.) Immunoassay test kits also allowed for the soil excavation to be completed during one (1) mobilization, which fixed project mobilization costs and allowed for adherence to a tight project schedule.
