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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. Additionally, a sub-slab depressurization system was installed in the 2410 and 2412 tenant spaces and began continuous operation in 2020. No additional remedial actions are planned for this Site at this time.
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 July-December 2023 semi-annual period, nor is any further sampling 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 July 10 and October 30, 2023, with results provided in Quarterly Groundwater Sampling Reports dated August 3 and December 15, 2023. The most recent quarterly sampling results indicate that Perc concentrations remain above the Enforcement Standard, but continue to remain 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.
Sump Water Treatment System Sampling: Three (3) sump water treatment systems were in operation within the Ace Hardware building during the July-December 2023 semi-annual period. The two (2) newer additional systems began operation on September 3, 2023. Discharge sampling is completed monthly and results are submitted electronically, as required. The results of the monthly sampling continue to show all contaminants in the treated effluent reduced to levels well below the permitted discharge limits and generally below the Limits of Detection, (including Perc concentrations above the Enforcement Standards in sump influent samples). Therefore, the treatment systems continue to be effective in preventing any contaminants from discharging into the City of South Milwaukee stormwater sewer system and ultimately Lake Michigan. The sump water treatment systems will continue to operate following Case Closure.
Case Closure: A Case Closure form and addendum report were submitted on August 14, 2023, proposing closure by incomplete or eliminated exposure pathways. WDNR's letter of October 16, 2023, requested additional vapor intrusion investigations prior to approving the case closure request. A work plan will be submitted proposing a methodology for the required sampling. Field activities will be scheduled following WDNR approval. An amended case closure request will be submitted following completion of the field sampling activities.
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