2022 – 2024: In 2024, the US Environmental Protection Agency (EPA) sent a letter requesting sampling for per- and polyfluoroalkyl substances.

Expanded:

• Groundwater well network including new monitoring wells
• Optimized the extraction and injection network based on plume dynamics 

Initiated the source area flush initiative by direct injection and extraction in source area. 

Continued:

• Soil vapor monitoring 
• Groundwater long-term monitoring plume treatment system
• Plume capture and containment 

2021: Expanded the groundwater well network including new monitoring, extraction and injection wells.

Continued:

• Developing future source area remediation plan
• Additional source area investigations
• Soil vapor monitoring
• Plume capture and containment
• Plume treatment system

2020: Released the fourth Five-Year Review Report.

2017: Expanded the groundwater well network. Initiated the soil vapor extraction (SVE) optimization. Released the vapor intrusion investigation framework.

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system

2016: Expanded the groundwater well network and main treatment system capacity.

Continued: 

• SVE studies
• Groundwater monitoring
• Plume capture and containment
• Plume treatment system

2015: Expanded the groundwater well network (including monitoring, extraction, and injection).

Released:

• Third Five-Year Review Report
• Final Remedial Design/Remedial Action Work Plan Phase I; Source Area Remediation
• Source area treatability study details (Final Technical Memorandum #1)

Continued: 

• SVE studies
• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

2012 – 2014: Expanded the groundwater well network (including monitoring wells in all subunits).

Completed: 

• Beneficial reuse of treated water at the St. Thomas Aquinas Church for the HVAC system 
• Source Area Remediation Focused Feasibility Study
• Northwest injection system
• SVE Phase I and II optimizations
• Proposed Plan for the Main Dry Wells Source Area (public comment was in 2014)
• Record of Decision Amendment signed Sept. 30, 2014

Continued: 

• Groundwater investigations
• Operation & Maintenance (O&M) improvements on extraction and treatment systems
• Pumping and hydraulic control

2010: Installed two piezometers, 17 monitoring wells, one extraction well and three injection wells.

Completed: 

• The northeast treatment system expansion project in September
• The main treatment system was expanded to include an additional air stripper
• Conversion of well MW-29 into an extraction well 
• Second Five-Year Review in September 

2006 – 2009: The EPA issued an Action Memorandum addressing perchlorate cleanup levels for PGAN to be 14 micrograms per liter (µg/l). Buildings were demolished at the Unidynamics facility in July 2009.

The following were installed: 

• Nine monitor wells, one groundwater extraction well (EA-06 and EA-05) and one groundwater re-injection well 
• EA-06 treatment system located at the Goodyear Community Park in December 2007
• EA-05 treatment system located on Maricopa Flood Control District lands north of I-10 near Litchfield Road in March 2008

2002 – 2006: The EPA conducted Phase II groundwater investigation and a subsurface soil gas investigation in 2006. A consent decree was reached between EPA and Crane Co. for past expenses by EPA and investigation and cleanup by Crane Co.

Continued:

• SVE treatment system
• Investigated nature and extent of trichloroethene (TCE) and perchlorate contamination
• Investigated effectiveness of treating perchlorate-contaminated groundwater at the City of Goodyear's wastewater treatment plant 

1994 – 1998: An SVE treatment system was installed in 1994 that included a thermal oxidation unit equipped with exhaust scrubber. In 1998, perchlorate contamination was discovered and began to be included in the current groundwater monitoring regime.

1990: In September, the EPA issued an Administrative Order directing Unidynamics to proceed with soil and groundwater remediation as described in the EPA's 1989 Record of Decision. The groundwater portion of the remediation program involved extracting the groundwater, removing the contaminants by air stripping with emissions control, and reinjecting the treated water into the same aquifer upgradient of the plume or discharging the treated water to the Roosevelt Irrigation Canal.

1983 – 1984: The EPA added PGAN to the National Priorities List in September 1983. The EPA began a Remedial Investigation (RI) of the area now known as the Phoenix-Goodyear Airport (PGA) to characterize the site, discover the extent of the contamination, and identify possible sources. From this 1984 study, the entire site was divided at Yuma Road into a north and a south portion.

1963 – 1981: Unidynamics operated a research, design and manufacturing facility for ordnance and related equipment from 1963 to 1993. Several different chemicals, including solvents such as TCE, acetone and methyl-ethyl-ketone, were used in manufacturing devices and were reportedly disposed of in drywells at PGAN. The Arizona Department of Health Services (ADHS) discovered the groundwater contamination in 1981.

2022 – 2024: In 2024, the US Environmental Protection Agency (EPA) sent a letter requesting sampling for per- and polyfluoroalkyl substances.

Expanded:

• Groundwater well network including new monitoring wells
• Optimization of the extraction and injection network based on plume dynamics 

Continued:

• Soil vapor monitoring 
• Groundwater long-term monitoring plume treatment system
• Plume capture and containment 

2021: Expanded the groundwater well network including new monitoring, extraction and injection wells.

Continued:

• Soil vapor monitoring
• Plume capture and containment
• Plume treatment system

2020: Released the fourth Five-Year Review Report.

2017: Released the vapor intrusion investigation framework.

Expanded:  

• Groundwater well network (including monitoring, extraction, and injection)
• Plume treatment system

Continued: 

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system

2016: Released the explanation of Significant Differences related to select stabilized fill not requiring institutional controls.

Expanded:  

• Groundwater well network (includes monitoring, extraction, and injection)
• Plume treatment system

Continued:  

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system

2015: Released the third Five-Year Review Report

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

2014: Expanded the groundwater well network (including extraction wells) and plume treatment system for Subunit A.

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

2013: Expanded the groundwater well network (including monitoring wells in Subunit C).

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

Completed:

• Well abandonment and well replacement activities for Subunit A
• Enhancements/improvements on the treatment systems

2012: Expanded the groundwater well network (includes monitoring wells in Subunit C).

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

Completed: 

• Well abandonment and well replacement activities for Subunit A and GAC-04
• Maintenance on the Subunit A treatment systems 

2011: The EPA took over as lead Agency for PGAS in the fall (EPA was already the lead Agency for PGAN), which helped the EPA initiate/manage the study of the area between the sites (the area between PGAN and PGAS). The area between sites study was an action item from the Five-Year Review. 

2010: Expanded the groundwater well network (includes two new Subunit C monitoring wells).

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components) 

Completed:

• Five-Year Review — a protectiveness determination of the remedy was not made in the report, but was deferred until further information was obtained
• A pulsed pumping evaluation of the Southern Subunit C plume
• Well rehabilitation was completed on three Subunit A wells (E-12, E-7, and NE-5) and on Subunit C wells I-201 and I-203 

2009: Goodyear Tire and Rubber Company recommended pulsed pumping to overcome hydraulic stagnation and to address the residual contaminant mass in Southern Subunit C groundwater. 

Expanded the groundwater well network (included 2 monitoring wells).

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)

2008: Completed the update to the Operation & Maintenance (O&M) Manuals and completed sampling for metals.

Continued:

• Groundwater monitoring 
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)
• O&M activities of the groundwater treatment systems 

2004 – 2007: Completed the installation of extraction well (E-102) in November 2004 and completed the Five-Year Review Report in September 2005.

Continued:

• Groundwater monitoring
• Plume capture and containment
• Plume treatment system (including extraction, remediation, and beneficial use components)
• O&M

1994 – 1998: There are two plumes within Subunit C associated with the site, caused by conduit wells, which were promptly abandoned. Groundwater extraction and treatment of these two plumes began in 1994 using granular activated carbon. In April 1998, ADEQ approved the closure and decommissioning of the SVE system. The Vadose Zone Leaching Model was used to determine that the residual threat to the groundwater was below the maximum contaminant level. The Goodyear Tire and Rubber Company has thereby satisfied the requirements under the 1991 Consent Decree for closure of soils.

1993: Tetrachloroethene (PCE) was detected in PGAS Subunit A groundwater wells coming from the Western Avenue PCE Water Quality Assurance Revolving Fund (WQARF) (dry cleaning) site due east and upgradient of the PGAS plume.

1992: Goodyear Tire and Rubber Company conducted a removal action of metal contaminated soils located at the sludge drying beds. The soils containing chromium and cadmium above the Health Based Guideline Levels were stabilized, thereby eliminating the risk of exposure by ingestion and inhalation and preventing further migration to groundwater.

1989 – 1991: The Remedial Investigation/Feasibility Study for the site was completed in June 1989, and a comprehensive final remedy Record of Decision was signed in September for PGAN and PGAS. A Consent Decree for the final remedy was lodged on May 7, 1991, and entered in November, with the EPA, the State, Goodyear Tire and Rubber Company, and Loral Defense Systems as signatories. This document required Goodyear Tire and Rubber Company to remediate the Subunit B/C aquifer and contaminated soils.

1981 – 1984: The Arizona Department of Health Services (ADHS) discovered groundwater contamination in 1981. The EPA added the site to the NPL on Sept. 8, 1983. In 1984, TEPA began a remedial investigation of the Litchfield Airport Area (presently known as the Phoenix-Goodyear Airport) to characterize the site, discover the extent of the contamination, and identify possible sources. From this study, the site was divided at Yuma Road into a north and a south portion.

1942-1974: PGA served as the Litchfield Park Naval Air Facility since 1942. Goodyear Tire and Rubber Company began operating Goodyear Aerospace at the airport, modifying and repairing aircraft, which were then transferred to the adjoining Navel Air Facility from 1940 to 1945. In 1946, the Naval Air Facility was placed in modified maintenance status. Its primary function became the preservation and activation of military aircraft. 

In 1968, the Navy transferred ownership of the property to the City of Phoenix. In 1974, Goodyear Aerospace discontinued using TCE at PGAS.