2026: In February 2026, ADEQ reviewed the soil-gas data collected for Property A and determined that the soil remedial objective and criteria for closure had been achieved. The geographical extent of Property A was removed from the WQARF site as a partial site closure. 

2025: Rebound monitoring was conducted at Property A and Property B. This consisted of periodic soil-gas sampling.

2024: As of June 2024, approximately 106 pounds of tetrachloroethene (PCE) and trichloroethene (TCE) have been removed from the subsurface at the site. The Soil Vapor Extraction (SVE) system at Property B was turned off and a rebound evaluation was initiated.

2021 – 2023: The Final Remedy was implemented at the site. Operations, Maintenance, and Monitoring (OMM) was ongoing. As of June 2023, approximately 97 pounds of PCE and TCE have been removed from the subsurface at the site. The SVE system at Property A was turned off and a rebound evaluation was initiated.

2020: The Feasibility Study (FS) Report and Proposed Remedial Action Plan (PRAP) were finalized in February. The Record of Decision was signed in June.

2018 – 2019: Additional soil-gas and groundwater investigations were conducted as part of the Remedial Investigation (RI). The Final RI and Feasibility Study (FS) Work Plan were finalized in October.

2017: The site was listed on the WQARF Registry in January. The RI began by investigating groundwater and soil-gas within the Site investigation area. An Early Response Action (ERA), an SVE system, was implemented in November.

2016: ADEQ completed the Stone Avenue and Grant Road Preliminary Investigation (PI) in February.

2015: PCE and TCE were found at a Leaking Underground Storage Tank (UST) facility at the northeast corner of the Stone and Grant WQARF site at concentrations of 515 micrograms per liter (µg/L) and 5.73 µg/L, respectively.

2014: The City of Tucson conducted soil and soil-gas sampling at the site. PCE was not detected above laboratory detection levels in the eleven soil samples collected from four soil borings. PCE was detected in all four sub-slab soil-gas samples ranging from 22,000 to 450,000 micrograms per meter cubed (µg/m3).

2005: PCE was detected in the regional aquifer in one of two Sleepy Hollow Mobile Home Park domestic wells, located approximately 0.6 miles from the Stone and Grant WQARF site at a concentration of 2.8 µg/L.

1940s – 2000: Dry cleaning facilities operated at the site. In 1963, a gas explosion occurred at a dry cleaners located onsite. Natural gas and dry cleaning solvent containing PCE were released. The explosion destroyed the existing building. The facility was rebuilt, and dry cleaning operations resume.