Roll back the clock to 1892. The Bay City manufactured gas plant chugs along, converting coal and oil to combustible gas. The gas is distributed throughout the community and used by businesses and residents for cooking, lighting and heating until 1942, when operations on the site are shuttered, leaving behind a site contaminated by coal tar and purifier waste.

Fast forward more than 100 years, when remedial response was completed to facilitate redevelopment of the Bay City Manufactured Gas Plant (MGP) site for mixed residential and commercial use. The project included excavation and insitu soil stabilization (ISS) with cement. Excavation extended to about 22 feet below ground level, which is about 18 feet below the groundwater table and the surface of the nearby Saginaw River. ISS consisted of mixing impacted soil with cement to encapsulate the contaminants, thereby preventing contaminant migration. SME conducted soil borings to evaluate the extent of impact, developed project specifications, and assisted with selection of a qualified remediation contractor.

SME also provided oversite during the installation of six inclinometers and monitored the stability of an existing high voltage underground electrical line. SME designed a sheet pile cofferdam to maintain the stability of the excavation and the high voltage electrical line. In addition, a groundwater dewatering system was installed to allow excavation in a dry condition. SME collected soil samples from the excavated area to verify that impacted soil had been sufficiently removed.

A total of 22,800 tons of soil was excavated and disposed offsite in a State licensed landfill, and about 5,000,000 gallons of groundwater was treated onsite prior to discharge to the City of Bay City wastewater treatment plant (WWTP). ISS operations resulted in about 3,700 cubic yards of soil stabilized with cement.

Restoring former MGP plant sites to safe and productive use is just one way SME’s passionate people build and revitalize our world.