Environmental Protection Agency (EPA) #: AZD980695902

Superfund National Priority List (NPL) Placement: 1983

Location

The Phoenix-Goodyear Airport (PGA) Superfund site is located primarily in Goodyear, Maricopa County, approximately 17 miles west of Phoenix, in the western part of the Salt River Valley in central Arizona.  EPA determined two distinct sources that have impacted area soil and groundwater, and has designated the PGA Superfund site as two work areas:

• PGA-North (PGAN) with a source area near a former Unidynamics Phoenix Incorporated (UPI) facility and a mostly northward trending groundwater plume.
• PGA-South (PGAS) with a source area near a former Goodyear Aerospace/Loral facility and multi-aquifer groundwater plumes impacting areas south by southwest and also northwesterly. 

The impacted groundwater plumes are elongated and irregular, but to assist in visualizing the impacted area the site can be roughly framed by Indian School Road on the north, Dysart Road to the east, Broadway Road on the south, and Bullard Avenue to the west.  Even though about 11 square miles are framed, the plumes’ irregular footprint area extent is estimated at less than 5 square miles. 

The PGA site lies almost entirely within Goodyear, Arizona. Municipal exceptions include the airport proper, which is owned by the city of Phoenix, and an area near Litchfield Road which is within the city of Avondale.  Land use on and near the site includes agriculture, residential, commercial and industrial development.

Contaminants of Concern

Groundwater is impacted by organic compounds and metals.  PGA-North groundwater is impacted by trichloroethene (TCE), perchlorate, methyl ethyl ketone (MEK) and acetone.  PGA-South groundwater is impacted by TCE, tetrachloroethene (PCE), 1,1,1 trichloroethane (TCA), 1,1-Dichloroethylene (1,1 DCE), carbon tetrachloride, chloroform, chromium, and arsenic. 

Some source area soil is impacted by organic compounds and metals.  Organic compounds reported in select source area samples include TCE, PCE, MEK and acetone.  Metals have been detected in some soil samples.  Within select source areas, concentrations of chromium, cadmium, aluminum, and copper exceed Arizona Department of Health Services (ADHS) health-based clean up levels in some soil samples.

Public Health Impact

There is no current site health risk due to groundwater exposure.  Contaminated groundwater is not used as drinking water. Captured groundwater is treated and reinjected or used for a non-drinking water use.  There is no current health risk from exposure to soil or soil vapor since source surface soil exposure has been minimized and near surface contaminant levels are low. 

Some of the inorganic compounds detected at the site, such as chromium, are more toxic than others. Chromium has been identified in some water samples taken from the site in both the trivalent and hexavalent states. Chromium compounds in the trivalent (+3) state are of a low order of toxicity. At PGA-South, chromium in the groundwater is approximately 80 percent hexavalent and 20 percent trivalent.

Environmental Considerations

Within the PGA site there are no unique habitats nor any threatened or endangered species. Native vegetation is sparse. However, located south of the site, the lower Gila River represents an important riparian habitat. Species that inhabit or migrate through the Gila River area include four federally listed or endangered species. These are: the Brown Pelican (Pelecanus occidentalis), the Yuma Clapper Rail (Rallus longirostris yumanensis), the Peregrine Falcon (Falco peregrinus) and the Bald Eagle (Haliaeetus leucocephalus). The PGA area, particularly near the Gila River, supports mourning dove, Gambel’s quail, and various waterfowl.  Burrowing owls have been documented within the framed site region.

Site Hydrogeology

The PGA Superfund Site hydrostratigraphy is generally described in three subunits:

Subunit A
Interbedded sands, silty sands, and clayey sands with localized sand and gravel sequences. Extends from the ground surface to approximately 110 feet below ground surface (bgs) near PGA-South and generally deepens northerly. Localized, well-developed caliche has been encountered above and below the groundwater level.  In 2016, groundwater was encountered by 70 feet bgs in PGA-South.   However, PGA-North groundwater depth is variable across the plume footprint. Groundwater depth varies from 90 feet bgs to 140 feet bgs, depending upon the location along the elongated north-to-south plume footprint. Historically, the PGA-North Subunit A groundwater flow direction was north-northwesterly toward regional groundwater depressions created by irrigation water extraction.  Changes in irrigation and municipal extraction practices and locations during the early- to mid-2000’s pulled the groundwater plume northeasterly (north of Interstate-10).  To counteract the eastern component, more recent remediation extraction wells and subsequent plume-edge clean water injection (creating hydraulic barriers) have created some localized groundwater flow direction shifts toward the west/northwest. PGA-South overall Subunit A groundwater flow direction is southwest. The contaminant plume flows from the east side of the former Loral property to the south-southwest under the airport property and is contained by extraction and re-injection of treated water at the southwest plume boundary.

Subunit B
Unconsolidated silt and clay deposits with interbedded lenses of fine to coarse sand with depths extending from approximately 110 to 160 feet bgs near PGAS, and 160 to 230 feet bgs at PGAN.  Integrity varies across the site. Where not developed as an aquitard, Subunit B may allow contaminant leakage to Subunit C. Groundwater movement is generally considered to be non-continuous laterally and, where developed, an aquitard without a consistent horizontal groundwater flow.

Subunit C
Unconsolidated and interbedded mixtures of silty sands, clayey sands, and fine- to coarse-grained sands. Extends from approximately160 to 310 feet bgs at PGAS, and 200 to 350 feet bgs at PGAN. Groundwater movement is generally north to northwest.

Actions Taken

PGA-North groundwater cleanup remedy includes five groundwater pump and treat systems (capturing Subunit A, B, and C groundwater) and returning cleaned water using a combination of reinjection, infiltration and irrigation.

PGA-South groundwater cleanup remedy includes two groundwater pump and treat systems (capturing Subunit A and C groundwater) and returning cleaned water with beneficial reuse or permitted discharge to a water conveyance feature (ditch).

Soil clean up is complete, at both PGA-South and PGA-North source areas. The site utilized soil vapor extraction for soil clean up.  At PGA-South, select surface and near surface soil was either excavated or stabilized in-place to minimize exposure and exercise chromium source control.

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