Air Force dismantles groundwater treatment plant at Castle

  • Published
  • By AFRPA / PA
  • Air Force Real Property Agency
The Air Force Real Property Agency marked a major achievement in the groundwater cleanup program at the former Castle Air Force Base this month by dismantling a groundwater treatment plant that is no longer needed. Built in 1994, the Operable Unit (OU) 1 plant, located on the southeast side of the base, treated the highest levels of groundwater contamination. In 2003, the Air Force in consultation with environmental regulatory agencies, shut down the plant as contaminant levels were reduced significantly. The last remaining concentrations are now treated by two other treatment plants operating on the former base.

"Basically, this plant worked itself out of a job," said Phil Mook, Air Force Real Property Agency's Senior Representative. "It's especially gratifying to see the end point to this process and to see that our cleanup system design to capture and clean the underground plume worked as predicted."

Castle Air Force Base closed in 1995 under the Base Realignment and Closure Act (BRAC). By late 2006, all 2,777-acres were transferred from the Air Force to the community.

Groundwater contamination was discovered in 1979. Under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA), the Air Force conducted investigations, constructed new base water supply wells, and installed and operated a groundwater treatment system network. The Air Force, US Environmental Protection Agency (EPA), State Department of Toxic Substances Control, and Regional Water Quality Control Board all worked closely to ensure safe drinking water on and off base.

Located in the central base area, the groundwater under OU 1's plant initially contained contaminant concentrations of 500-700 parts per billion. The source was from past maintenance operations with solvents, mostly trichloroethylene (TCE). The pump and treat system at OU 1 reduced those concentrations to below 40 parts per billion and the Air Force turned the system off in 2003 with approval from the environmental regulators. Remaining groundwater cleanup at Castle is now addressed by the OU 2 and Phase 3 groundwater treatment plants, both located on the western base boundary. Groundwater cleanup will continue until TCE concentrations are reduced to the maximum contaminant level of 5 parts per billion. Between 1994 and 2003, the OU 1 system treated more than 1.6 billion gallons of groundwater and removed approximately 700 pounds of contaminants.

All cleanup decisions under CERCLA have been finalized at Castle and all soil cleanup is complete, with the exception of an ongoing cleanup at the Petroleum Fuel Farm Area. The groundwater cleanup is expected to be completed within 20 years.

AFRPA acquires, manages and disposes of Air Force-controlled real property worldwide. The agency's BRAC division has managed the remediation and transfer of more than 77,000 acres of property at 35 former installations to local communities for economic development.

Media Contact:
Linda Geissinger
Public Affairs Officer
Air Force Real Property Agency
916-643-1250 x 109