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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 second semi-annual 2020 reporting period. The third quarter sampling was performed on July 14, 2020, with results provided in the Quarterly Groundwater Sampling Report dated July 31, 2020, and the fourth quarter groundwater sampling was performed on October 12, 2020, and the results were provided in the Quarterly Groundwater Sampling Report dated November 20, 2020.
The quarterly sampling results indicate that PAH groundwater concentrations continue to fluctuate, particularly in MW-4. The site has been backfilled historically with materials containing coal and cinders, which contribute to the PAH groundwater concentrations. The variability in PAH concentrations in groundwater are likely influenced by fluctuations in the groundwater table within the impacted backfill. The most recent groundwater concentrations in MW-4 for Benzo(a)pyrene, Benzo(b)fluoranthene, and Chrysene remain above the Enforcement Standards, though having decreased for the last three consecutive quarters.
The PAH concentrations in MW-3 also fluctuate between sampling events, but largely remain at levels above the Enforcement Standard. The PAH concentrations observed in MW-3 in October 2020 are nearly identical to results of both the May and July 2020 sampling events. The groundwater concentrations are influenced by the change in groundwater table elevation change and the large amount of contaminated fill material within the area of MW-3 and along the southern property boundary. This monitoring well has been damaged as a result of snow removal operations.
No active remediation is currently being conducted, nor is any proposed. While PAH concentrations in MW-3 and MW-4 continue to fluctuate with no discernable trend, the contamination appears to be isolated to the immediate area of the two (2) monitoring wells. The most recent sampling data do not indicate an increase or spread of contamination. 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.
Another quarterly sampling event is planned for January 2021 and the sampling results will be submitted in a quarterly report. A second quarter sampling event will be scheduled.
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