Background

We Energies is completing a Remedial Investigation (RI) under a Great Lakes Legacy Act (GLLA) project agreement for the former Third Ward MGP Site (Site), and the encompassing Operable Unit 2 (OU2). Foth was retained to investigate contaminated sediment in order to characterize the occurrence of PCBs, PAHs, and metals within OU2, and delineate the degree and extent of visible NAPL and potential MGP-related wastes adjacent to the Third Ward MGP Site.

Approach

Foth evaluated existing sediment chemistry data and NAPL observations from the MGP Site, river bathymetry, and core log information to support the development of a focused sediment investigation strategy.
The sediment investigation included collection of a total of 50 sediment core samples from the Milwaukee River, for processing and visual examination, followed by analyses of select samples for target contaminants, including PCBs, PAHs, and RCRA metals.

Results

The characterization will better delineate the estimated elevation of contamination relative to the interface between underlying native materials throughout OU2; the lateral and vertical extent of contamination; the geotechnical properties of the sediment; and the lateral and vertical extent of observed NAPL adjacent to the MGP Site. The outcomes of the study will be used in conjunction with OU1 data for completion of a feasibility study under a Legacy Act Agreement between WEC and EPA-GLNPO.