Revised On: Feb. 16, 2024 - 1:35 p.m.

2021: Two groundwater monitoring events were conducted at the site — the spring sampling event in March 2021 and the fall sampling event in September 2021. A total of 86 groundwater samples were retrieved in 2021.

2020: The Draft Remedial Investigation (RI) Report was released in April. The Proposed Remedial Objectives (RO) Report was released in June. The Final RI Report and Feasibility Study (FS) Work Plan were released in July.

2016 – 2019: Installed additional groundwater monitoring wells to characterize the distribution of groundwater contamination at the Site.

2015: In fiscal year 2015, one groundwater monitor well was installed and a total of 98 groundwater samples were retrieved.

2014: In FY 2014, a total of 8 groundwater monitor wells were installed and a total of 99 groundwater samples were retrieved. A draft Remedial Investigation (RI) report was submitted in June 2014.

ADEQ monitored Salt River Project (SRP) well 17.9E-7.5N and three nearby groundwater monitor wells in 2008. Sampling of the SRP well indicated a tetrachloroethene (PCE) concentration of 6.8 micrograms per liter (µg/L). The PCE results from the other wells ranged from below the Aquifer Water Quality Standards (AWQS) of 5 µg/L for PCE to 67 µg/L. In FY 2014, a total of 8 groundwater monitor wells were installed and a total of 99 groundwater samples were retrieved. A draft RI report was submitted in June 2014, but was later put on hold due to the need for futher investigation.

2008: In the spring and winter, ADEQ installed three additional groundwater monitor wells: two east of 40th Street along Weldon and Whitton Avenues and one in the Osborn Road alignment between 39th Street and 40th Street. The initial depth-specific groundwater samples collected from the wells had PCE concentrations that ranged from less than the laboratory reporting limit to 110 µg/L.

During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 6.8 µg/L. The maximum PCE concentration observed throughout the site was 67 µg/L. 

2007: In June, ADEQ sent out notices per A.R.S. §49-287.03 initiating the remedial investigation for the site. During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 24 µg/L.

In December, ADEQ installed an additional groundwater well, located on 39th Street north of Indian School Road. The initial groundwater samples collected from the well had depth-specific PCE results that ranged from less than the laboratory reporting limit up to 310 µg/L.

2005 – 2006: Routine groundwater monitoring was conducted at the site. PCE was detected in the SRP well at concentrations of 41 µg/L and 28 µg/L. 

2003: ADEQ installed a groundwater monitoring well in the Osborn Road alignment between 39th Street and 40th Street. The initial groundwater sample collected from the well had PCE concentration that was below the AWQS of 5 µg/L. During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 110 µg/L.

2000: In May, the site was placed on the WQARF Registry with a score of 30 out of a possible 120.

1983 – 2002: Groundwater samples were generally collected by SRP from their well, 17.9E-7.5N, which is located west of the Osborn Road alignment and 40th Street. A sampling event, conducted in January 1998, yielded the highest detection of PCE yet observed in the SRP well, a concentration of 210 µg/L.