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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: Two (2) quarterly groundwater sampling events were conducted during the first semi-annual 2023 reporting period. Quarterly groundwater sampling for Perc was conducted at MW-5 on January 6 and April 21, 2023, with results provided in Quarterly Groundwater Sampling Reports dated February 7 and May 19, 2023. The most recent quarterly sampling results indicate that Perc concentrations remain above the Enforcement Standard and are generally stable.
Active treatment of the groundwater recovered by the Ace Hardware building sump continues, but no active remediation to further reduce concentrations in the subsurface is currently being conducted, nor is further remediation proposed at this time. Chemical treatment activities were last performed in January 2022. Quarterly sampling will continue until a Case Closure Letter is issued for the Site. A Case Closure Report is to be submitted in August 2023. The Case Closure Report will propose exclusion from the requirement to reduce concentrations based upon an incomplete exposure pathway. Drinking water is provided by the municipality via Lake Michigan and there are no potable groundwater wells on-site.
PFAS Sampling: WDNR approved the completion of per- and polyfluoroalkyl substances (PFAS) sampling in an email dated November 7, 2022. No additional PFAS groundwater sampling activities were conducted during the January-June 2023 semi-annual period.
Sump Water Treatment System Sampling: The sump water treatment system within the Ace Hardware building has continued to operate. 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. Two (2) additional sumps/systems began to be installed in July 2023. Information necessary to obtain an updated WPDES approval has been provided to WDNR. Discharge will begin following approval. The sump water treatment systems will continue to operate following Case Closure.
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