16th Street and Camelback | Site History

2020: Conducted groundwater sampling in March.

2019: ADEQ completed two additional rounds of enhanced reductive de-chlorination (ERD) injections in January and April and conducted groundwater sampling in April and October.

2018: ADEQ completed two additional rounds of ERD injections to accelerate the Monitored Natural Attenuation (MNA) remedy. Two replacement groundwater monitoring wells were installed to replace wells that have gone dry due to decreases in the groundwater levels.

2017: ADEQ finalized the Record of Decision (ROD) and completed an additional round of ERD injections. ADEQ evaluated the option to increase the frequency of ERD injections to accelerate the MNA remedy.

2016: ADEQ finalized the Proposed Remedial Action Plan (PRAP) for public review and comment. ADEQ initiated an ERD injection to determine if ERD could be cost effectively implemented to expedite the proposed remedial option of MNA. Groundwater sampling results are currently being compared to determine viability of this option.  If effective, this technology may be incorporated into the final MNA remedy for the site to facilitate accelerated site delisting.

2015: ADEQ finalized the Remedial Investigation (RI) report, Feasibility Study (FS) work plan, and the FS report. Groundwater monitoring and sampling was conducted in February and March 2015. The sampling results show that contaminants of concern were continuing to attenuate.

2014: Two groundwater monitoring wells were installed at the site to delineate the down gradient extent of the northern plume. Groundwater samples were collected from all of the site wells that could be accessed in February and April. Based on the April 2014 groundwater sampling event, the current highest concentration of tetrachloroethylene (PCE) and dichloroacetic (DCA) in groundwater is 13.3 micrograms per liter (µg/l) and 0.62 µg/l, respectively. The sampling results for dichlorophenol (DCP) continue to show no concentrations above laboratory reporting limits.

2013: Based on the May groundwater sampling event, the highest concentration of PCE in groundwater was 31.9 µg/l. Groundwater samples for 1,2-DCA concentrations remain below the laboratory detection limit. ADEQ is in the process of installing two groundwater monitoring wells to further define the down gradient extent of PCE contamination of the North Plume.

2008: ADEQ continued to sample the northern and southern groundwater plumes.

2007: Based on the October groundwater sampling event, the highest concentration of PCE and 1,2-DCA in groundwater was 24 µg/l and 3.4 µg/l, respectively.