Published June 23 2012
Diversion Discussion: Proposed meandering channel draws questions from authority board
But seeing what it looks like can offer a different impression, Fargo-Moorhead Diversion Authority officials learned this month.
For the first time publicly, board members saw what the possible final design could look like near the channel’s outlet north of Argusville.
Reach 1, as it’s called, is the first portion of the 35-mile diversion channel Army Corps engineers and local consultants are designing around Fargo. Reach 1 begins at the outlet structure near Georgetown, Minn., and extends upstream about four miles on the diversion channel.
A final design for Reach 1 should go before the Diversion Authority board at its July meeting.
At the board’s June 12 meeting, officials saw a draft rendering that represented what the area near the outlet could look like, with 65 percent of the design work complete.
The design is subject to changes and more study, but a visible feature in the rendering drew quick skepticism.
At the base of the channel, engineers propose designing a “meandering low-flow channel” that could offer a permanent aquatic habitat.
The discussion June 12 was prompted when the Diversion Authority was asked to approve several routine work orders, which reflect ongoing design work and studies for the $1.8 billion project.
One of those work orders included a request to authorize further study on how the meandering channel would work and how large it could be.
The June 12 meeting appeared to be the first time Diversion Authority members became aware of the proposed meandering channel, but the feature has been in the works for a long time.
It’s mentioned as one of many environmental mitigation alternatives detailed in the several-hundred-page feasibility study released last summer by the U.S. Army Corps of Engineers.
The low-flow channel is intended to offset environmental impacts from terminating the Rush and Lower Rush rivers where the rivers join the diversion channel, corps project manager Terry Williams said.
Instead of building control structures or aqueducts as with other rivers the diversion crosses, both the Rush and Lower Rush will be permanently diverted into the Red River diversion.
It means abandoning 2.1 miles of the Rush River and 3.4 miles of the Lower Rush River between where they meet the diversion channel and where they naturally converge with the Sheyenne River.
According to the corps’ feasibility study, the rivers have “limited habitat value,” but the project sponsors are still required to mitigate the environmental effects of the lost riverbeds.
That’s where the idea for the proposed meandering channel came in.
The low-flow channel would be in use year-round in at least the final 11 miles of the Red River diversion, providing an aquatic habitat and wetland for wildlife, the feasibility study states.
“A low-flow channel is a channel that is typically in the center of a larger channel, which is sized to handle small flows from drains ditches or groundwater,” the study states.
The study proposes a 10-foot-wide by 3-foot-deep channel that “could meander back and forth within the 250- to 400-foot-wide diversion channel bottom.”
But here’s where design and further study could mean significant differences from the feasibility proposal.
Bruce Spiller, technical services manager for the diversion’s project management team, said engineers are designing the low-flow channel so it can be effective mitigation, but it won’t threaten the structural integrity of the diversion itself.
Spiller said the most current design plan for Reach 1 is for a bottom channel width of 300 feet, which would allow for
200 feet for the low-flow channel to wind back and forth, while giving it
50 feet of buffer on either side.
Diversion Authority members Kevin Campbell and Rodger Olson had several specific questions for Spiller after seeing the rendering for the first time June 12.
Campbell questioned how the low-flow channel would adequately mitigate the fish and river habitat lost from the Rush and Lower Rush rivers.
Olson was concerned about erosion the meandering channel could create inside the Red River diversion once the project is in operation.
Spiller said the proposed low-flow channel has been “vigorously debated” between corps engineers and local consultants.
“We recognize that and we want to look at it,” Spiller said in response to Olson. “We’ve still got a large study going on, which is getting authorized by this task order to vet that out even further.”
Fargo engineer Mark Bittner added, “We did challenge the corps and had them look at the West Fargo (Sheyenne Diversion) to see if there were things that happened there that we could learn from. These studies are looking at that.”
The Houston-Moore Group, one of the lead local consultants on the project, is heading up the $284,300 study on the low-flow channel for the Reach 1 design.
Spiller said it’s possible the meandering low-flow channel could be featured throughout the entire diversion channel, but that hasn’t been decided.
Open house Tuesday for F-M diversion project
FARGO – The U.S. Army Corps of Engineers and the Fargo-Moorhead Diversion Authority are hosting a public open house Tuesday to provide project design updates for the first segment of the proposed Red River diversion project.
Reach 1 begins at the outlet structure near Georgetown, Minn., and extends upstream about four miles on the diversion channel.
The corps’ open house will be held from 6 to 8 p.m. at the Holiday Inn, 3803 13th Ave. S., Fargo.
Anyone interested in the project is welcome to attend.
There will be no formal presentation but officials with the corps and the diversion authority will be on hand to answer questions.
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