Project Background
While conducting routine maintenance work at a natural gas compressor station in Martin County, Kentucky, the client found elevated levels of PCBs in bottom-sediment samples from a new, aboveground water tank. Based on these results, the site had apparently been impacted by historical releases of PCBs. Afterwards, AGES performed a supplemental characterization and proposed further action to address PCBs in paint, oil, concrete and water at several locations throughout the site. After AGES conducted delineation sampling to further evaluate the extent of PCB-affected components, it was determined that remedial action was required throughout the compressor building, the warehouse building and the office building. Response actions began in 2011, with AGES performing oversight of the field work and collecting confirmatory samples, as required.
Remediation Project Work
Coating or Removing PCB-Impacted Paint
The method of paint removal and surface preparation varied according to the client’s specifications and conditions of the component. During paint removal, plastic containment structures were constructed around the established work areas to prevent cross-contamination into adjacent areas. When “dust-free” equipment was used by the contractor, containments were neither required nor constructed.
For some areas, all damaged paint was removed from surfaces using abrasive methods such as manual scraping, shot-blasting or brush-grinding. The area was then double-washed and rinsed. After preparation, the surfaces were double-coated with two layers of contrasting-colored paint, in general accordance with the continued use authorization under 40 CFR 761.30 (p) (A) (1).
For some metal components, the client opted for complete removal of all PCB-impacted paint, both damaged and intact. In general accordance with 40 CFR 761.79, complete paint removal was completed to meet the NACE 2 standard for blasting to a near-white finish. Once the standard was achieved, all PCB-impacted paint was assumed to have been removed, no confirmation sampling was required, and the area was painted with a single coat of epoxy per the client’s corporate standards.
For some concrete components, the client opted for complete removal of all PCB-impacted paint, both damaged and intact. If complete paint removal from concrete that had not been previously characterized was performed, concrete chip samples were collected to confirm that all PCB-impacted paint was removed and to confirm that the underlying concrete was not impacted by PCBs. The area was then re-painted per the client’s corporate standards.
Cleaning PCB-impacted, Non-painted, Non-porous Surfaces
PCB-impacted, non-painted, non-porous surfaces (such as non-painted rafters, shelves, equipment surfaces, etc.) were cleaned in general accordance with 40 CFR 761 Subpart S, using manual scrubbing, approved cleaning detergents and solvents and several clean rinses. Spill control methods were used to control liquids during surface washing activities to prevent cross-contamination with adjacent areas. After the cleaning, confirmation wipe samples were collected for analysis of PCBs. Cleaning continued until the action level was achieved.
Removing PCB-impacted Concrete
Concrete components that were impacted with PCBs at levels exceeding action levels were scabbled/scarified to remove the affected areas or double-coated per 40 CFR 761.30 (p) (A) (1). Scabbling of concrete surfaces was performed using a “dust-free” decontamination system, which incorporates a high-performance vacuum and waste packaging unit, or within an applicable containment structure. After the scarification was complete, confirmation concrete chip samples were collected for analysis of PCBs. Scarification continued until the action level was achieved. When required, complete concrete removal was performed using a jack-hammer.
Cleaning PCB-Impacted Sumps, Basement Troughs, and Drain Lines
Prior to cleaning, all oil, water, and sediment present in the PCB‑impacted sump, basement trough or drain line was removed using pumps, shovels or other manual methods. The sump and trough was cleaned with a high-pressure washer or like equipment to remove any residual debris. Any pumps present within the sumps were removed and replaced.
PCB‑impacted drain lines or drain lines leading to and from an impacted sump were cleaned. Prior to cleaning, accumulated fluids and sediment were vacuumed from the lines. If needed, the inlets and outlets were scrubbed with wire brushes to remove scale. Appropriate tanks were staged on polyethylene at the discharge end of the line to collect cleaning fluids and the line was cleared with a roto-tool, as required. Each line was then double-washed/rinsed with a jet-tool in general accordance with the procedure specified above from 40 CFR 761 Subpart S, including washing with detergent, water rinse, washing with solvent, and final water rinse. All cleaning fluids were collected and containerized for later disposal.
Cleaning Tanks and Containers
In general accordance with 40 CFR 761.79, tanks and other large containers were cleaned by flushing the internal surfaces of the tank or container three times with an approved solvent. Each rinse used a volume of the flushing solvent equal to approximately 10 percent of the tank or container capacity.
