| Comments: |
Background: 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.
Quarterly Monitoring Well Sampling: Two (2) quarterly groundwater sampling events were conducted during the second semi-annual 2021 reporting period. The third quarter sampling was performed on August 31, 2021, with results provided in the Quarterly Groundwater Sampling Report dated September 29, 2021, and the fourth quarter groundwater sampling was performed on November 11, 2021, and the results were provided in the Quarterly Groundwater Sampling Report dated December 27, 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 the Preventative Action Limits (PALs) 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.
PFAS Sampling: In addition to conducting quarterly groundwater sampling activities, groundwater sampling was performed on all monitoring wells on August 5, 2021, as part of the assessment of potential groundwater impact for polyfluoroalkyl substances (PFAS). (PFAS sampling of MW-3 and MW-5 had been previously completed in March 2021 during the preliminary evaluation of emerging contaminants.) The August 2021 sampling was performed following the methodology proposed in the July 18, 2021, dated PFAS Additional Evaluation Work Plan. The results of the most recent PFAS sampling (and the March 2021 emerging contaminant sampling) were provided in the Emerging Contaminant Evaluation Report Amendment dated October 18, 2021. The report indicated that 1,4-Dioxane and n-Nonane were not identified in the groundwater at any location, but several PFAS constituents were observed in each of the monitoring wells. As noted in the October 2021 report, many of the PFAS constituents observed were reported at concentrations below the recommended Preventative Action Limits (PALs), or are listed constituents with no recommended PAL. However, exceedances of the recommended PALs for one (1) or more PFAS constituents were observed in each monitoring well, and all monitoring wells except MW-201 indicated exceedances of the recommended Enforcement Standards for cumulative PFAS constituents. In a response email of December 9, 2021, WDNR indicated that further evaluation must be completed to determine the source of the PFAS impacts. Additional sampling for PFAS is planned for the first semi-annual 2022 time period.
|
