DEQ using vegetation to stabilize riverbank

Friday, November 07, 2008
 JUSTIN ENGELTHE SAGINAW NEWS

Officials with the state Department of Environmental Quality Thursday updated residents on the cleanup along the Tittabawassee and Saginaw rivers.

About 80 residents attended a community meeting at the Horizons Conference Center in Saginaw Township, where Al Taylor, a Department of Environmental Quality geology specialist, spent a half-hour examining 2008's projects.

Highlights included remediation of the region surrounding the former 47 Building in Midland.

Before crews razed it in March 2007, the 47 Building was among nearly 500 structures on 1,900 acres along the Tittabawassee River at Dow Chemical Co.'s Michigan Operations complex. Scientists discovered traces of dioxin on land surrounding the former structure.

Taylor said crews removed and replaced contaminated soil there in the summer and early fall, then placed fencing to limit access to the site.

Dow also continued stabilizing areas of the Tittabawassee riverbank in danger of falling into the water, Taylor said. Such erosion poses the risk of sending contaminated soil into the waterway, he said.

''We want to control these as sources,'' Taylor said.

He said crews are attempting to leave a ''softer footprint'' on the environment as opposed to installing man-made devices or technology to replace the riverbanks.

One method includes planting vegetation to steady the erosion.

Taylor showed slides of one riverbank replaced last year that has sprouted sizable vegetation already.

In previous meetings, Taylor has showed diagrams illustrating how erosion has shifted the course of the river several feet in various directions over the decades. He compared a 2004 map of the river system with a 1937 map to show the difference.

He said crews continue to identify weak riverbanks.

Taylor said the state environmental group continues to monitor a region near a dioxin ''hot spot'' adjacent to the Dow plant that investigators identified in 2007. Crews built a dam around the spot to prevent contaminated sediment from escaping downstream as Dow-hired dredgers cleaned up.

Employees worked on and around an area containing dioxin at levels near 87,000 parts per trillion, found in soil 6 inches to 1 foot beneath the riverbed.

The job finished before the winter, and Taylor said officials are determining how to ''cap'' the removed riverbed with new soil and take away the coffer dam. v
 

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