Roll back the clock to 1892. In Bay City, Michigan a manufactured gas plant (MGP) 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.

MGPs operated across the country from the late 1800s through the mid 1900s prior to installation of natural gas pipelines. Byproducts of MGPs consisted of coal tar and purifier waste. Coal tar is a dark, viscous fluid that does not readily dissolve in water. Purifier waste is a mixture of wood chips and iron filings used to remove chemicals from the gas before the gas is distributed to consumers.

SME began providing environmental services to help clean up the Bay City site in 2001. We evaluated the extent of contamination and provided oversite during remediation of soil impacted by coal tar.

Fast forward to 2018 when remedial response was completed to facilitate redevelopment of the 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 monitoring 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 waste water treatment plant (WWTP). ISS operations resulted in about 3,700 cubic yards of soil stabilized with cement. Sevenson Environmental Services out of Niagara Falls, New York was the remedial contractor.

Helping to restore former MGP plant sites to safe and productive use…it’s one way SME’s passionate people help to build and revitalize our world.