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Background: To address Tetrachloroethylene (Perc) contamination identified in the area of a former dry cleaner (tenant spaces addressed as 2410-2412 10th Avenue) at the Sunrise Shopping Center facility, chemical treatment was conducted between May 2019 and January 2020, and a sub-slab depressurization system was installed/operated in the 2410 and 2412 tenant spaces beginning in 2020. No additional remedial actions are planned for this Site at this time.
Quarterly Monitoring Well Sampling: Quarterly groundwater sampling for Perc was conducted at MW-5 on August 2 and October 3, 2022, with results provided in Quarterly Groundwater Sampling Reports dated September 26, 2022, and November 7, 2022. The quarterly sampling results continue to show Perc in MW-5 at concentrations above the Enforcement Standard. The most recent results (October 2022) indicate continued stability in concentration in MW-5. Quarterly sampling will continue until a Case Closure Letter is issued for the Site. A Case Closure Report is currently being prepared.
PFAS Sampling: In addition to conducting quarterly groundwater sampling activities, a final round of groundwater sampling for per- and polyfluoroalkyl substances (PFAS) was performed in August 2022 from all 10 monitoring wells installed on-site. The groundwater sampling procedures and results were discussed in the Emerging Contaminant Evaluation Report Second Addendum dated October 12, 2022. The report indicated PFAS concentrations were highest at the most upgradient monitoring well (MW-603) and decreased to below the applicable standards on-site in the downgradient direction, indicating an upgradient, off-site source of PFAS. WDNR approved the completion of PFAS sampling in an email dated November 7, 2022.
Sump Water Treatment System Sampling: The sump water treatment system within the Ace Hardware building has continued to operate, and two (2) additional sumps/systems are planned for installation. Discharge sampling is completed monthly and results are submitted electronically, as required. The results of the monthly sump influent sampling continue to be stable but above the Enforcement Standards, while all contaminants in the treated effluent are reduced to levels well below the permitted discharge limits and generally below the Limits of Detection. Therefore, the treatment system is effective in preventing any contaminants from discharging into the City of South Milwaukee stormwater sewer system and ultimately Lake Michigan. The sump water treatment system will continue to operate following Case Closure.
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