2022 – 2024: ADEQ conducted groundwater sampling at the site. ADEQ published the Proposed Remedial Action Plan in August.

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 80 groundwater samples were retrieved in 2021.

2020: The Feasibility Study (FS) was released in July.

2019: The Draft Remedial Investigation (RI) Report was released in July. The Proposed Remedial Objectives Report was released in September. The Final RI Report and FS Workplan were released in November.

2018: A deep groundwater monitoring well was installed at the source in April.

2016: ADEQ conducted groundwater investigations to characterize the distribution of impacted groundwater at the site.

2015: Groundwater monitoring and soil gas monitoring activities were being conducted throughout the site. A total of 66 groundwater and 33 soil vapor samples were collected.

2014: Groundwater monitoring and soil gas monitoring activities were being conducted throughout the site.

As part of the early response action, Salt River Project (SRP) operated a soil vapor extraction (SVE) system. By January 2012, approximately 319 pounds of tetrachloroethene (PCE) had been removed from the soil. In April, the SVE system was dismantled by SRP in order for ADEQ to install a new system. It was anticipated to be installed in 2015. Site investigation and groundwater well installation continued.

2013: To further delineate the soil vapor plume, ADEQ installed 56 temporary soil vapor wells. The soil vapor concentrations of PCE ranged from <11 micrograms per cubic meter (µg/m3) to 830 µg/m3.

ADEQ also installed 56 temporary soil vapor wells.  The results of soil vapor sampling delineated the PCE soil vapor plume at concentrations greater than the residential indoor air screening level of 9.4 μg/m³.  The soil vapor plume extended from the southwestern portion of the Arcadia Towne Center southwest to an area near 44th Place, between East Fairmount and East Indianola avenues.

ADEQ went door to door to collect indoor air samples from residents located above the soil vapor plume to check for vapor intrusion. Out of 40 homes, 14 participated and granted access for their indoor air to be sampled. 

Additionally, ADEQ collected indoor air samples from 30 classrooms at Arcadia High School. Only one of the 14 indoor air samples collected in the residential areas contained PCE at a concentration greater than the residential indoor air screening level of 9.4 μg/m³. After confirmation sampling, results indicated PCE was less than the screening level, indicating the original sample was affected by normal household activities. PCE was not detected in any of the indoor air samples collected at Arcadia High School greater than the screening level.

2012: ADEQ installed seven SVE and six SVE observation wells adjacent to the Sandy’s Cleaners facility in preparation for the modification of SRP’s SVE system. ADEQ also conducted an SVE pilot test. The results from the test suggest that SVE would be an effective treatment technology for the site. SRP decommissioned their SVE system in April in order for ADEQ to manage the construction, operation, and maintenance of a new SVE treatment system.

ADEQ also installed three additional groundwater monitoring wells south to southwest of the Sandy’s Cleaners facility and conducted sampling of the soil vapor monitoring wells throughout the site. Cone Penetrometer Testing was also performed throughout the site to investigate current hydrogeologic conditions. A routine groundwater monitoring event was conducted in April. 

2011: ADEQ continued to collect passive soil gas samples from 39 locations placed adjacent to the Sandy’s Cleaners facility and near North 45th Place. The PCE mass observed in those samples ranged from less than 25 nanograms (ng) up to 3,512 ng. As a result of the PCE results, ADEQ installed 12 permanent soil vapor monitoring wells adjacent to the passive soil gas sample locations. The initial soil vapor samples collected from these wells had PCE concentrations that ranged from 16 µg/m3 to 59,000 µg/m3.

SRP continued to operate their SVE system and as of December, approximately 319 pounds of PCE had been removed from the vadose zone soil. During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 1,400 micrograms per liter (µg/L).

2010: SRP continued to operate their SVE system and as of June, approximately 314 pounds of PCE had been removed from the vadose zone soil. During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 370 µg/L.

2009: In January, ADEQ collected passive soil gas samples from approximately 14 sites located within North 45th Place, south of Indian School Road. By July, the SVE system had removed approximately 310 pounds of PCE from the soil in the vadose zone. Routine groundwater monitoring was not conducted.

2008: By the end of March, approximately 309 pounds of PCE were removed from the vadose zone by the SVE system. ADEQ installed two additional groundwater monitor wells on 47th Street, north of Indian School Road. The initial groundwater samples collected from the wells had PCE results that were equal to and below the Arizona Water Quality Standard (AWQS) of 5 µg/L. During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 33 µg/L.

2007: In June, ADEQ sent out notices per A.R.S. §49-287.03 initiating the remedial investigation for the site. As of the end of September, approximately 295 pounds of PCE were removed from the vadose zone by SRP’s SVE system. During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 100 µg/L.

2006: In February, SRP began operating their SVE system, which was installed west of the Sandy’s Cleaners facility. By September, the SVE system had removed approximately 248 pounds of PCE from the vadose zone. During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 98 µg/L.

2004: SRP installed two SVE wells west of the Sandy’s Cleaners facility. A Non-Title V Air Quality Permit from Maricopa County for their SVE system received approval.

2001: As part of the Interim Remedial Action (IRA) agreement, SRP installed two groundwater monitor wells east of the Sandy’s Cleaners facility and one groundwater extraction well west of the Sandy’s Cleaners facility.

2000: ADEQ and SRP entered into a Governmental Services Contract in which ADEQ funded SRP to conduct an IRA at the site. As an IRA, SRP would design and install an SVE system to remove soil vapor contamination from the subsurface.

1999: In April, the site was placed on the WQARF Registry with a score of 27 out of a possible 120.

1997 – 1998: The Arizona Department of Health Services evaluated the data collected in 1996 and provided three health consultations that determined there was no risk to employees under current use scenarios. In May, ADEQ collected grab groundwater samples from five wells. The PCE concentrations in the samples ranged from less than the laboratory reporting limit up to >2,500 µg/L.

During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 4,300 µg/L.

1996: Ten soil borings were drilled west of the Sandy’s Cleaners facility. The soil concentrations of PCE ranged from 0.0011 milligrams per kilogram (mg/kg) to 0.2 mg/kg. Soil vapor samples that were also collected had a maximum PCE concentration of 5,600 µg/L in one boring at a depth of 15 feet below ground surface.

During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 4,000 µg/L.

1994: One groundwater monitor well was installed southwest of the Sandy’s Cleaners facility on the Arcadia High School grounds. The initial groundwater samples collected from the well had shallow and deep PCE results that were below the AWQS of 5.0 µg/L.

During a routine groundwater monitoring event, the maximum PCE concentration observed throughout the site was 3,000 µg/L.

1992: Eight soil borings were drilled west of the Sandy’s Cleaners facility. The soil concentrations of PCE ranged from 0.024 mg/kg to 0.440 mg/kg. A wastewater sample was collected from the facility’s lint trap in which the measured PCE concentration was 150 µg/L. ADEQ also installed two groundwater monitor wells: one directly west of the Sandy’s Cleaners facility and one northwest of SRP’s well 19.0E-8.1N. The initial groundwater sample collected from the well directly west of the Sandy’s Cleaners facility had a PCE concentration of 2,300 µg/L.

1989: Soil gas surveys were conducted at multiple facilities throughout the East Central Phoenix study area to determine if a release of contaminants to the subsurface had occurred. In October, one soil vapor sample was collected adjacent to the Sandy’s Cleaners facility. The concentration of PCE detected in the soil vapor sample was 670 µg/L.