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Site Investigation for Former MGP Site


Foth was engaged by Superior Water, Light and Power (SWL&P) to complete a site investigation at a former manufactured gas plant (MGP Site). The Site consists of both upland and sediment areas. Foth’s scope of work included combining data collected by previous consultants into a single report, evaluating the completeness of the data set, developing a conceptual site model, and recommending future work for the Site.


The Site is located within an industrial area, which includes railroad tracks, a concrete plant and a City Wastewater Treatment Plant (WWTP). The shoreline in the vicinity of the Site has evolved over time, primarily as a result of several phases of construction at the City’s WWTP, development of other industrial operations, and construction of railroad infrastructure. Just off the shoreline to the north, there is a boat slip. The boat slip has historically been maintained through periodic dredging events conducted over the years, in order to maintain adequate draft conditions. Overall, the distribution of impacted material is consistent with the former locations of features associated with historic MGP operations. However, some anomalous distributions are evident, primarily along utility alignments.

Detections of benzene, naphthalene, and benzo(a)pyrene have been documented more frequently and more broadly across upland areas of the Site than other targeted compounds, and are used as indicator chemical of concern (COCs) for evaluating the overall extent of MGP impacts in soil and groundwater as well as developing the remedial strategy for the site.


Foth prepared a Remedial Action Options Report (RAOR) to evaluate options for a remedial strategy to address upland soil, groundwater and sediments. Remedial design activities will occur in 2021 with remedial construction tentatively anticipated in 2021 and 2022.



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