South Mesa | Site History

2018 - 2019: ADEQ continued implementation of the ISCO Pilot Test and MNA at the Site.

2017: Groundwater elevations were measured in January and April 2017. Groundwater flow is to the north. Groundwater samples were collected in January 2017. Contaminants of concern (COCs) concentrations were similar to previous results Tetrachloroethene (PCE) concentrations ranged from non-detect to 11 micrograms per liter (µg/L). Trichloroethene (TCE) concentrations ranged from non-detect to 8.0 µg/L.  Cis 1,2-dichloroethene (1,2-DCE) concentrations ranged from non-detect to 55 µg/L.

2016: Groundwater elevations were measured in February, July, and October 2016. Groundwater flow is to the north. Groundwater samples were collected in February and July 2016. Contaminant concentrations were similar to previous results with only PCE, TCE and 1,2-DCE exceeding their respective AWQS. ADEQ finished the Proposed Remedial Action Plan (PRAP) and Record of Decision (ROD). The remedy is MNA.

2015: Groundwater samples were collected from SRP wells 28E-0N and 28.5E-1N. No contaminants were detected in the groundwater samples.

2014: ADEQ completed the FS Report in April. ADEQ collected groundwater samples in March and November. Only monitor wells located at the former Applied Metallics facility contained PCE at concentrations greater than the AWQS of 5 µg/L.

2013: ADEQ finalized the RI report in June. ADEQ collected groundwater samples from 15 monitor wells in September 2013. Six monitor wells contained PCE exceeding the AWQS of 5.0 g/L.

2012: ROs were solicited from the public to complete the RO report and finalize the RI report.  The draft FS work plan was written and noticed was provided to the public. ADEQ collected groundwater samples from 17 monitor wells in May and 16 monitor wells in December. Six monitor wells contained PCE exceeding the AWQS of 5.0 µg/L in May and seven monitor wells contained PCE exceeding the AWQS in December.

2010: In May, a monitor well (MW-5) in the vicinity of Broadway and Extension Roads was abandoned at the request of the property owner.

2008: The SVE was shut down and removed from the site in May.

PCE, TCE, and cis-1,2-dichloroethene (DCE) were the only VOCs of potential concern detected in the groundwater samples collected in May. PCE was the only VOC detected above the AWQS. The highest PCE concentration was detected in the on-site Well MW-AM-8S at a concentration of 6.7 µg/l exceeding the AWQS of 5.0 µg/l.

An additional well (MW-14) was drilled and installed in October to evaluate the groundwater plume south of the former Applied Metallics facility. The well was screened in four subunits (UAU1-UAU4). MW-14 was sampled in November. VOCs were not detected in any of the aquifer subunits.