Former manufactured gas plant (MGP) operations at this 14-acre site included retort coal gas and carbureted water gas manufacturing processes that commenced in 1899. The MGP structures were demolished in the 1950s, and the remaining service facility structures were removed by 2012.
In 2010, the City of Ann Arbor, Michigan, implemented a riverfront redevelopment plan that included a whitewater play park and walkway at a property immediately across the river from the site. The utility-owned property was then placed on a fast-track for a highly public site remediation, presenting challenges based on the expedited schedule and public interest.
From the outset of the project, TRC was instrumental in devising a strategy to obtain the required MDEQ approvals, and then providing the design and managing the bid, award and execution of a sediment cleanup in this challenging environment—all in less than a year’s time.
Beginning in 2008, TRC’s work at the site initially included source area, soil, groundwater and sediment investigations, followed by the focused removal of the former gas holder, upland soil, impacted bank soil and sediment. TRC provided the remedial design and oversight of construction activities, with work continuing to the present.
A key feature of the project included remediation designs, specifications and construction oversight for the installation of a 925-foot–long NAPL-trapping cap (Patent No. 8,419,314) to trap and remove both LNAPL and DNAPL coal tar residuals before they could migrate to the adjacent Huron River. The cap as designed and installed results in no ongoing energy inputs, requires no active groundwater withdrawal/treatment, and produces no air emissions or wastes.
The bulk of the project is now complete. DTE has formally solicited proposals for the future use of the site, which may include partial use as a riverside park and/or mixed use commercial development.