2024 – 2026: Technical Project Planning (TPP) meetings were convened to ensure comprehensive management and technical oversight of the ongoing per- and polyfluoroalkyl substances (PFAS) Remedial Investigation (RI). These critical sessions enabled project managers, technical leads, and subject matter experts to collaboratively finalize the RI work plan, encompassing sampling protocols, analytical methodologies, data quality objectives, and the scope of the PFAS contamination investigation.

2021 – 2023: Annual inspections of Site S were conducted to ensure that access remains restricted and that signage is intact and legible.

2020: The third Five Year Review was prepared by the US Army National Guard.

2018: A Land Use Control Implementation Plan (LUCIP) for Site S was submitted to ADEQ.

2016: The second Five Year Review was completed and submitted to ADEQ for review.

2012: Remedial activities moved forward at an underground storage tank release site.

2011: ADEQ submitted comments on the Remedial Investigation/Feasibility Study (RI/FS) draft report, a final RI/FS and a proposed plan describing remedial actions were developed.

2010: An RI/FS work plan was submitted in May as per the recommendation of the site inspection conducted in 2005. In June, field work began at the site and the RI/FS draft report was submitted to ADEQ for review in September.

2004 – 2005: A site investigation began in May 2004 and was completed in fall 2005. An additional Military Munitions Response Program (MMRP) site was discovered during the site investigation that indicated the presence of contamination. Follow-up phases/actions were executed as required in the individual site cleanup strategies.

2003: The Phase 3 Army Range inventory was completed at Papago Park Military Reservation (PPMR) in May. The inventory identified one site as eligible for the MMRP. The Phase 3 inventory serves as the preliminary assessment under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA).

1985: Since the mid-1980s to present, numerous environmental investigations have been conducted at multiple PPMR locations for specific environmental concerns. Due to the age of the facility, earlier records are not available for many of the historical environmental practices. PPMR is currently a Resource Conservation and Recovery Act (RCRA) small quantity generator of hazardous waste, and generates various solid and universal wastes. The facility has not applied for a RCRA Part A or Part B treatment, storage and disposal facility permit. According to ADEQ, the facility has not received a notice of violation for noncompliance with environmental regulations.

1946 – 1985: In 1946, a combined support maintenance shop (CSMS) (Building M5354) was established for the purpose of servicing and maintaining approximately 150 vehicles. Since that time, two more CSMSs have been established at the facility (Buildings M5340 and M5370). However, only Building M5370 currently continues to operate as a CSMS facility. In 1973 and 1985 operational maintenance shops #4 and #7, respectively, were established to service and maintain small vehicles. Both facilities remain as maintenance facilities. Based on the few records available and interviews with past and present employees, petroleum naphtha has historically been the primary solvent used. Limited quantities of trichloroethane (TCA) and chlorinated hydrocarbons have been used, primarily by the Army Aviation Support Facility (AASF) and wash racks. Prior to 1973, the AZARNG did not maintain purchase and use records for solvents. Throughout the history of the facility, numerous underground and above ground storage tanks have been used for storage of fuels, waste oil and solvents.

1930: The Arizona Army National Guard (AZARNG) was established on April 21, 1930, by Public Law 92 of the 71st Congress. The act served to abolish the Papago-Saguaro National Monument and reserve public lands for military purposes, specifically a rifle range. Since the congressional designation in 1930, the PPMR has been an active military facility and rifle range. The current and historical activities at the facility include training and administration, aircraft fueling and maintenance activities, motor vehicle fueling and maintenance activities, fuel and solvent storage areas, gunnery ranges, detonation areas, and bunkers.

The PPMR mission has been consistent with training and administration since the facility was established. On-site training activities have and continue to include: aircraft fueling and maintenance, motor vehicle fueling and maintenance activities, fuel and bunker storage areas. Several training and operational practices were discontinued in the past including solvent storage areas, gunnery ranges, detonation areas, and long-term storage of hazardous materials.