Keel's Creek stream project preserves natural beauty

Tuesday, July 31, 2012
A view of the Keel's Creek project, showing the main channel on the left, with the rock wall and planted willow saplings. A secondary channel, on the right, put the Carroll-Boone waterline in danger. This secondary channel has been filled with creek rock and topsoil and has been seeded with bermuda grass. The large rocks will keep the downstream flow of the creek in the main channel. Photos courtesy of McGoodwin, Williams & Yates

EUREKA SPRINGS -- When downed trees and erosion changed the course of Keel's Creek south of Eureka Springs, officials at the Carroll-Boone Water District became concerned when their crews discovered a threat to the water pipeline.

That pipeline feeds 85 percent of Carroll-Boone's customers, downstream of the City of Eureka Springs, in Berryville, Green Forest, Harrison and subsidiary communities.

The problem area was 300 feet upstream from Rockhouse Road, where the pipeline crosses Keel's Creek, three miles south of the Rockhouse Road intersection with Hwy. 62. The area affected and project area encompassed 1,600 to 1,800 feet of streambank. Flooding over the years created a secondary channel in the creek, and continued erosion of its bank eventually brought the watercourse to within 3 feet of the water pipeline.

Chris Hall, project manager and engineer with McGoodwin, Williams & Yates (MWY) of Fayetteville, told the CBWD board in April, "A three-inch rainfall would finish it off."

He said the water district has a 50-foot easement, and had lost all of its easement on the south side of the line.

The sense of urgency was such that the board waived competitive bidding and approved an emergency engineering project to stabilize the pipeline.

The U.S. Army Corps of Engineers and the Arkansas Department of Environmental Quality issued permits within two weeks, which would normally take four to six weeks.

No one knew at the time that rainfall this Spring would be any different from the previous two years, when heavy rains caused intensive flooding and washouts of roads and bridges throughout the county.

Hall told the board his goal was to put the creek "back to natural as much as possible while still protecting the Carroll-Boone waterline."

The project involved filling the secondary channel with rock, planting vegetation and creating a pool in another location as a backwater for excess flow.

At the July meeting, Hall gave a slideshow presentation on what happened and how it was repaired.

"Tall debris, five to six feet, kept undercutting and taking the bank downstream," Hall said. "We decided to build a large rip rap wall to armor the slope."

He said the landowner affected agreed for the district to reclaim its 50-foot easement.

MWY brought in an expert who does creek stabilization for the Arkansas Natural Resources Commission, who also brought a friend who works for the U.S. Army Corps of Engineers and has worked all over the country on this kind of project.

"They gave us advice for free and helped us design this," Hall said. "This is used all over the U.S. with success."

They used materials from the creek itself, such as six huge, downed trees with crisscrossed roots and other debris, to create a pool for the creek to back up into during flooding on the upper end of the project area.

For the wall portion along the main channel, the contractor built a wall 20 to 30 feet into the bank and used 1,700 tons of rock.

The construction is called a "Bendway Weir." According to the Corps of Engineers website, it is a "low-level, upstream-angled stone sill, attached and keyed into the outer bank of a bed.

"The weirs are angled from 5 to 25 degrees upstream, built of a well-graded stone with an upper weight limit of 650 to 1,000 pounds, spaced 50 to 100 feet apart, typically 2 feet high at the stream end, rising to 4 feet at the bank end, with lengths varying from one-quarter to one-half the base flow width of the river or stream."

Hall said the contractor drilled down to bedrock to anchor the wall down. They also bought willow saplings and planted them every 50 feet along the bank.

"They suck up water and make a great natural barrier," Hall said.

They also used sycamores on the upper end against the bank.

The secondary channel was filled with creek rock, covered with about 10 inches of topsoil and then seeded with bermuda grass.

The grass seeding may not take, Hall said, because of the drought.

"The contractor has been watering, but it may have to be reseeded in the fall."

He said the landowner was pleased with the result.

"He was tickled pink because he said he'd been battling this for a long time and didn't have the means to fix it."

Hall said the original time frame for the project was four weeks, but the contractor, Evans and Evans of Madison County, accomplished it in two. They hired a special operator who has done this work before.

Plant manager John Summers said the work was done with local materials and help.

"We used rocks from two local quarries," he said.

Total cost for the project will be $196,410.27. Of that, $52,000 went to engineering fees and $132,000 to the contractor. Other funds went to materials and other professional fees.

"The contractor did a wonderful job," Hall said. "It was a group effort with us, the contractor and Carroll-Boone."

He said he felt his goal of preserving the creek's natural setting was achieved.

"These creeks are beautiful, and the last thing you want to see is white rip rap," Hall said. "That's why we used natural materials so the creek can stay as pristine and pretty as God made it."

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