The way the river moves: Dow is working to find out

08/10/2006

Kathie Marchlewski , Midland Daily News

Starting at the Midland's Tridge, crews of "fluvial geomorphologists" -- that is, people who study rivers -- have been busily collecting samples of sediment, measuring depth and movement. They're starting first with six miles of the Tittabawassee, but plan to work on all 22 miles that stretch out to the Saginaw River. The goal: to figure out the best way to handle contamination without making it worse.

The work is The Dow Chemical Company's response to a sampling and study plan previously deemed unacceptable by the Michigan Department of Environmental Quality and U.S. Environmental Protection Agency. The agencies are, however, both in support of the "GeoMorph" process. The DEQ approved the plan in July and sampling began late that month.

"We believed it was a more comprehensive approach that we could conceptually get behind," said DEQ Geologist Al Taylor.

Dow had submitted remedial investigation work plans -- a requirement of its 2003 state-issued operating license -- to the state in December, and is revising that plan for resubmittal this December. The agreement on the GeoMorph process, however, allowed the company to get to work this summer instead of next.

"Rather than go through another round of paper, we found a way to get out in the field." Taylor said.

The process of examining the river in order to make informed decisions about future resolution is a speedier one than proposed, but it's not simple and it's not necessarily quick.

"This is a marathon, not a sprint," said Dave Richardson of Wisconsin-based ELM Consulting, LLC, which has also conducted work on contaminated rivers such as the Kalamazoo and Fox.

But Dow has committed itself and its resources to making the project as swift as possible. Traditionally, for example, analysis of soil for dioxins and furans takes longer than a week, about 10 days. For this project, however, Dow shopped for a lab that could do it in 48 to 72 hours.

Richardson calls the turn-around unprecedented.

But Dow and the state are eager to learn what they can and find a solution to the lingering dioxin and furan problem. Musser said the GeoMorphing is part of the corrective action tool kit. It could lead eventually to dredging to remove contamination, or it could lead to other remedies such as barriers that would prevent erosion of contaminants back into the river.

GeoMorphing -- the study -- is intended to provide information that will prevent recontamination. "Our approach looks at the balance between human and ecological risk," Richardson said. "You can't make any changes until you understand the whole picture."

He said the problem with conventional dredging is that "you have no idea if you've got it all or not." He calls Geomorphing more efficient. "When you get the end result, you know you've put your money where it's going to do the most good."

Along with identifying sediments, soils, sands, silts, and clay, crews are studying why and which sediment is collecting in different areas, based on various landforms that affect river movement.

"Rivers can be complex," Richardson said. "Right now we're looking at where deposits are."

Core samples are taken with three-inch tubes, which are driven to the bottom with a hammer and brought back up, capturing each layer of material. In the first section of river there are 620 sampling locations. Four samples will be drawn from each producing nearly 2,500 samples for the first section.

Field work is expected to be complete in October and a final report on the first six miles of river is due out in February.

Musser said the project is an alternative to random sampling plans that have been discussed. "Random sampling doesn't tell you much of anything," he said.

©Midland Daily News 2006
 

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