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Superfund Site | Former Williams Air Force Base: Page 3 of 3

Status

Remedial activities continue at the following sub-sites:

  • LF004 — Remedial activities include soil vapor extraction (SVE), In-Well Air Stripping (IWAS) and oxidant injection. SVE has been used to remove potentially harmful vapors (TCE and PCE) from the subsurface in the former above ground storage tank (AST) and Southeast Landfill areas. IWAS employs a combination of technologies to remove contaminants from groundwater and unsaturated soils. Air stripping is used within an IWAS well to aerate the groundwater and transfer contaminants from the dissolved phase into the air, where the contaminants are removed by SVE. Oxidant injection directly into groundwater using permanganate has been used in several areas of the site to supplement SVE and IWAS. At the end of 2019, both SVE and IWAS had removed the vast majority of subsurface contaminants and both systems were shut down pending confirmation soil vapor sampling. Periodic oxidant injections continue to address residual contaminants in groundwater and semi-annual groundwater monitoring will continue until all contaminants are consistently below action levels.
  • ST012 — ST012 is the location of the former Liquid Fuel Storage Facility where petroleum fuel storage and distribution options were conducted from 1941 until decommissioning in 1991. SVE, Steam-enhanced Extraction (SEE), and Enhanced Bioremediation (EBR) have been employed to remove fuel contaminants from the soil and groundwater. Cleanup goals for shallow soil above a depth of 25 ft bgs were achieved following implantation of SVE treatment from 1994 to 1996. SVE continues to be operated to remove volatile contaminants from soils deeper than 25 ft bgs. SEE uses multi-phase extraction to remove LNAPL, contaminated groundwater and soil vapor from the aquifer. Steam is generated on site using boilers to provide steam to injection wells. Captured LNAPL is separated and recovered to the extent feasible to power steam generation, while contaminated groundwater is treated using onsite air stripping and granular activated carbon before being discharged to the municipal wastewater treatment plant. Soil vapor extracted during SEE is treated by thermal oxidation. SEE was implemented from September 2014 through April 2016. EBR was initiated in November 2018 to promote biological activity among bacteria that feed off of contamination present at the site. Continuing EBR activities include injection of sulfate into the groundwater and groundwater extraction to assist in circulating the sulfate throughout the contaminant plume. Periodic monitoring of groundwater will continue until attainment of all cleanup levels has been documented.
  • Parcel N — The U.S. Army Corps of Engineers (USACE) conducted a Site Inspection (SI) to investigate the potential occurrence of munitions and explosives of concern (MEC) and chemical warfare material (CWM) at the 17-acre Parcel N Debris Area 1. The munitions response included digital geophysical mapping (DGM) surveys and intrusive investigations. No MEC of CWM items were identified during the investigation of geophysical anomalies, or during a surface sweep using metal detectors. Additional investigation is necessary in a portion of the site currently covered by approximately 3-5 acres of asphalt, concrete and construction debris.

Monitoring and inspections continue at other sub-sites, as required (see Action Taken section on Page 2 for a list of these sub-sites).

PFAS impact is undergoing USAF evaluation.  The next phase is a Remedial Investigation that is tentatively scheduled for 2023.

Community Information

The U.S. Air Force (USAF) periodically presents site activity updates via mailed and internet-posted flyers. Please contact USAF representatives to learn about future information updates.

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