2024: In February and March, an injection pilot test consisting of enhanced in-situ bioremediation using the injection wells and extraction well was performed. ADEQ also conducted groundwater sampling.

2023: In January and February, two injection wells and four monitoring wells were installed and sampled at the site. A clean water injection test was subsequently performed to assess the performance of the injection wells. In March, the Feasibility Study (FS) Report was finalized. In May, a round of groundwater sampling occurred.

2022: ADEQ conducted groundwater sampling.

2021: ADEQ conducted pilot testing to assess the performance of enhanced in-situ bioremediation for the site and began preparing the FS report.

2020: The Final Remedial Investigation (RI) Report and FS Work Plan were released in April. A groundwater extraction well was installed and was tested to assess the hydrogeologic properties of the site.

2019: ADEQ issued the Draft RI Report in November.

2017-2018: ADEQ began the RI of the WQARF site to assess the extent of contamination and evaluate options to address the contamination. ADEQ does not have jurisdiction over private wells in Arizona and cannot require private wells to be taken out of service, but ADEQ will share results of any sampling with well owners and use the data to assist in ongoing investigation. City of Prescott water supply wells are not located within the groundwater contaminate plume and are not affected by the contamination at this WQARF site.

2016: The Miller Valley Road and Hillside Avenue site was placed on the WQARF Registry on December 12, with an eligibility and evaluation score of 40 out of 120. An investigation of a property on the southeast corner of Miller Valley Road and Hillside Ave found trichloroethylene (TCE) above its Aquifer Water Quality Standard (AWQS) of 5 micrograms per liter (µg/L).

2015: Groundwater sampling identified tetrachloroethylene (PCE), TCE, and cis-1,2-dichloroethene (cis-1,2-DCE) in several wells at the WQARF site. PCE concentrations in two private wells sampled in 2005 were found to have increased between 2005 and 2015. PCE concentrations in one well increased from 21 µg/L to 34.5 µg/L and in the other well from 270 µg/L to 418 µg/L.

2005: A soil and groundwater investigation found volatile organic compounds (VOCs) located west of Miller Valley Road on the north side of Fair Street, in the vicinity of two former dry cleaners. This site is the current location of a Fry's Food and Drug store. During site characterization activities, soil gas and groundwater with elevated VOCs were also found in the area of a current dry cleaning facility, located west of Miller Valley Road on the south side of Fair Street.

Site investigations included passive soil gas surveys, shallow groundwater sampling, and private well sampling. The VOCs detected in groundwater samples included PCE, TCE, and cis-1,2-DCE. PCE and TCE were present in groundwater at levels that exceeded the AWQS of 5 µg/L. Shallow groundwater closest to the former dry cleaning location was found to contain PCE with concentrations up to 17,000 µg/L. Two privately owned wells used for irrigation were found to contain PCE above the AWQS of 5 µg/L. PCE concentrations in these two wells were 21 µg/L and 270 µg/L, respectively.

2002: PCE and TCE were reported above AWQS at the WQARF site during a leaking underground storage tank investigation on the southeast corner of Miller Valley Road and Hillside Avenue. The investigation ruled out the leaking storage tank as the source of PCE and TCE.