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Polynuclear Aromatic Hydrocarbon (PAH) contamination was identified within two (2) areas at the Sunrise Shopping Center facility: within the area of a former heating oil UST behind the 2414B 10th Avenue tenant space (location of monitoring well MW-4) and within the southern extent of the site (location of MW-3). The PAH contamination continues to be monitored during quarterly groundwater monitoring.
Two (2) quarterly groundwater sampling events were conducted during the first semi-annual 2021 reporting period. The first quarter sampling was performed on January 18, 2021, with results provided in the Quarterly Groundwater Sampling Report dated March 3, 2021, and the second quarter groundwater sampling was performed on May 3, 2021, and the results were provided in the Quarterly Groundwater Sampling Report dated June 30, 2021. Quarterly sampling will continue until a Case Close Out Letter is issued for the Site.
The quarterly sampling results indicate that PAH groundwater concentrations in MW-3 and MW-4 continue to fluctuate with no discernable trend and are most likely influenced by changes in groundwater elevations in the impacted backfill. The PAH constituents of concern include Benzo(a)pyrene, Benzo(b)fluoranthene, and Chrysene. The PAH concentrations in MW-3 remain above the Enforcement Standards, and the PAH concentrations in MW-4 generally vary between slightly above Preventative Action Limits to slightly above the Enforcement Standards. The site-wide presence of fill material (including coal and cinders remaining from the historical use of the property) likely contributes to the observed PAH groundwater concentrations. (A large portion of the Site exhibits low-level PAH soil contamination.) However, the contamination appears to be isolated to the immediate area of the two (2) monitoring wells and the most recent sampling data do not indicate an increase or spread of contamination.
No active remediation is currently being conducted, nor is any proposed. There is no exposure to this residual contamination because drinking water is provided by the municipality via Lake Michigan and the groundwater ingestion route of exposure is incomplete. There are no potable groundwater wells on-site.
In addition to conducting quarterly groundwater sampling activities, groundwater sampling of MW-3 was performed on March 11, 2021, as part of a preliminary evaluation for potential contamination associated with emerging contaminants, specifically 1,4-Dioxane, n-Nonane, and polyfluoroalkyl substances (PFAS). The sampling was performed as proposed in the January 25, 2021, dated Emerging Contaminant Evaluation Work Plan. The results of the sampling for emerging contaminants were provided in the Emerging Contaminant Evaluation Report dated April 15, 2021. The report indicated that 1,4-Dioxane and n-Nonane were not identified in the groundwater at MW-3, but several other PFAS constituents were observed in MW-3 and MW-5. In a response letter dated May 19, 2021, WDNR indicated that further evaluation of the PFAS impacts should be conducted. Submission of a work plan and subsequent performing of the additional sampling for PFAS are planned for the second semi-annual 2021 time period.
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