2015 – 2023: ADEQ has been and will continue to conduct ongoing groundwater monitoring. The Record of Decision (ROD) identifying the site remedy as monitored natural attenuation with capture and treatment of residual PCE by the existing PGA-S groundwater treatment system was signed by ADEQ in June 2018.

2014: The Feasibility Study (FS) Report was finalized by ADEQ on April 23, 2014. ADEQ prepared the Proposed Remedial Action Plan (PRAP) and issue it for public comment on April 24, 2014. ADEQ issued the final PRAP on October 7, 2014.

2013: Groundwater samples were collected quarterly. The highest concentration of PCE in groundwater during the events was 7.8 ug/l at monitor well MW-1 in May. PCE was not detected at concentrations greater than the AWQS at any of the other monitor wells, including COG-01. To further develop the conceptual understanding of PCE at well COG-01, a time-series groundwater sampling was conducted from March 25 through April 16. The summary report was completed by the end of 2013.

EPA conducted an “Area Between the Sites” study to collect data to further define water level and water quality conditions in the area where the PGAN, PGAS and Western Avenue sites meet. The scope of the study included the surveying of selected wells in the area to a common region measuring water level elevations and collecting groundwater samples. The final results of the study were finalized in March.

2012: Groundwater samples were collected quarterly The highest concentration of PCE in groundwater during the events was 6.59 µg/l at monitor well MW-1 in May. Verification sampling was conducted in June to verify suspect VOC concentrations at selected wells during the May event. The results of the verification sampling and Aug. sampling indicated that PCE concentrations were within normal ranges (5.3 ug/l). A concentration of 6.2 ug/l was reported in Nov. at MW-1. The draft FS Work Plan was completed April 4th.

2011: Groundwater samples were collected quarterly from site monitor wells and groundwater elevations were captured monthly. In May, ADEQ installed passive diffusion bag (PDB) samplers in monitoring wells. In Aug.t and Nov., PDBs were placed at the depth in each monitor well where the PCE concentration was the highest, based on May vertical profiling. The highest concentration of PCE in groundwater during the four events was 12.0 µg/l at monitor well MW-1 in Nov. The AWQS is 5.0 ug/l.

2010: Groundwater samples were collected from site monitor wells in May and November. The highest concentration of PCE in groundwater in these two events was 6.8 µg/l at monitor well MW-1. 

2009: Groundwater samples were collected from site monitor wells in January. The highest concentration of PCE in groundwater was 4.5 ug/l at monitor well MW-2, less that the Aquifer Water Quality Standard (AWQS) of 5.0 ug/l. ADEQ finalized the RI report. The RI incorporated the remedial objectives report that was completed in January. The Feasibility Study (FS) phase began, and groundwater monitoring continues at the site. 

2008: Monitor well MW-8 was installed by ADEQ north of the City of Goodyear municipal well, COG-01 before the end of the year. Monitor well MW-8 was installed to provide data to define the northern boundary of the PCE impacted groundwater.

2007: The highest concentration of PCE detected in groundwater during the August monitoring event was 12 µg/l at monitor well MW-2.

2006: The highest concentration of PCE detected in groundwater was 3.2 micrograms per liter (µg/l) in the March sampling. The draft RI report including the Land and Water Use report, was submitted for public comment in August.

2005: Current and Future Beneficial Land and Water Use report was conducted as part of the draft RI report.

2003: In March, the Industrial Survey report was finalized as part of the draft RI report. 

2002: In October, a draft Industrial Survey was completed as part of the draft  RI report which focused on potential source areas. The data obtained from the Industrial Survey indicated that additional source investigations would not be required as part of the RI. 

2001: In March, ADEQ conducted a soil gas survey at the former Aladdin Dry Cleaners property. Results of the soil gas survey indicated minor concentrations of PCE.  In July, ADEQ began a remedial investigation (RI) at the site. 

2000: In October, ADEQ installed five monitor wells as part of an early response action (ERA). The purpose of the ERA evaluation was to (1) better define the lateral and vertical extent of contamination, (2) gain a better understanding of where the source area may be located, and (3) to determine the approximate mass of PCE within the plume.

1998: The site was placed on the WQARF Registry in December with a score of 51 out of a possible 120.

1995: Two monitor wells were installed to characterize the groundwater quality east and north of the PGAS.

1994: ADEQ conducted Preliminary Investigations in 1994 and 1995. Soil vapor sampling at the City of Goodyear Public Works facility and also at Western Dry Cleaners. The soil vapor sampling did not detect any significant concentrations of PCE. 

1993: Tetrachloroethene (PCE) was detected upgradient of the EPA National Priority List  PGAS. Subunit A wells at the PGAS showed an increasing trend in PCE in shallow groundwater.