161st Air National Guard

161st Air National Guard | Site History

1951 - 1972: In 1951, the federal government authorized the construction of a new National Guard Base at PSHIA. The land is owned by the City of Phoenix (COP). The 197th Fighter Squadron was the first occupant of the new base. In 1960 the squadron was renamed the 161st Fighter Group. In 1961, the group was designated to the 161st Air Transport Group to fly cargo/passenger missions for the Military Air Transport Command until 1968. From 1968 to 1972, the Phoenix Air Guard was designated as the Aeromedical Airlift Group. The 161st Air Refueling Group has occupied the base since 1972.

Throughout the history of the base, a number of fighter, cargo, and air refueling aircraft have operated from the base. Typical activities at the site included aircraft fueling maintenance, ground equipment maintenance, and other associated activities.

Over the years, waste streams at the site have included fuels and oils, various solvents and paint thinners, and other chemicals. In the earlier years of site operation, many fuels and oils were disposed of through an oil/water separator and then to a storm drain. Some flammable wastes were disposed of at the airport’s Fire Training Pit.

1988: The 161st ANG became a part of the IRP. In July, a preliminary assessment (PA) for the site was completed. The PA identified four areas of potential contamination.

1990: Remediation activities began in December. Activities included a soil gas survey, geophysical testing, monitor well installation, piezometers, and regular groundwater monitoring events.

1992: The National Guard Bureau (NGB) completed a draft final site investigation report. According to the report benzene, ethylbenzene, tetrachloroethene (PCE), trichloroethene (TCE),  dichloroethene (DCE), and 1,2-dichloroethane (DCA) were detected in monitor wells at the base. The NGB installed 12 new monitor wells as part of the IRP Site #6 petroleum, oils, and lubricants storage area source characterization. COP installed three monitor wells.

The most significant contamination is associated with petroleum hydrocarbons, specifically benzene, at IRP Site #6. In this area, soil contamination was evident. Groundwater contamination from this area included a plume of benzene that remains within the borders of the facility, and well within the borders of the PSHIA.

1996 - 1999: An interim remedial action (pilot test) was performed. The pilot test consisted of an SVE and air sparge (AS) system. Large quantities of methane were removed during this time.

1999: In June, a decision document presenting the selected soil remediation action was signed. The selected remedy included an SVE and AS system.

2000: In April, a final action memorandum was prepared by the 161st ANG.

2001: In February, the SVE/AS system was operational.

2003: In January, the AS portion of the treatment system was shut down due to concentrations of benzene below Aquifer Water Quality Standards of five parts per billion (ppb) for  the previous four quarters. This was due to the combined result of remedial activities and smearing caused by the historically low groundwater elevations. Semi-annual groundwater monitoring continued during this rebound period.