Greenbelt Lake dredging projected for October finish
By Iva Butler | (firstname.lastname@example.org)
Workers have removed more than 80 percent of the sediment that has been clogging Greenbelt Lake in Maryville.
About 30,000 cubic yards have been removed, with 7,000 cubic yards to go, said David Bishop, project manager for the U.S. Army Corps of Engineers.
The sediment is loaded into dump trucks and taken to the Alcoa-Maryville-Blount County Public Landfill, where it is used for cover. Wet sediment is left on the banks until it dries enough to pass a “paint filter test.”
Dredging of the lake should be completed and the fencing and heavy equipment removed from the area by the end of September, he said. The project began Feb. 11.
The contractor on the $3,047,260 project is ES&H of Knoxville.
Workers have sloughed off the shoreline areas and placed about 4,000 tons of rip-rap on the lake banks to stabilize the area, Bishop said.
From the shore to 6 feet into the lake, the water depth will reach about 1 foot. The 6-foot buffer will be a wetland area where plants that grow in water will be placed.
Past the rip-rap the lake will drop more steeply to an 8-foot depth, Bishop said. Near the dam, it may be deeper.
There will be a grassy area around the lake, forming a 10-foot buffer zone. Permanent grass will be planted there to stabilize the areas and filter out toxins and sediment from rainwater, Bishop said.
Dredging the lake, a project the city of Maryville has been pursuing since 2000, is being funded with 65 percent federal and 35 percent city funds.
Maryville’s share is $1,066,541, of which in-kind services totaling $404,000 will be credited to the city. These services include land and easements the city is providing for the project, which gave the contractor access to city property.
WEIR IS NEXT
The contractor has finished most of the excavation between the dam and the island feature, which is located off Parham Avenue near its intersection with East Harper Avenue.
Next week the contractor will construct a weir straddling close to the island at the upper end of the lake, Bishop said.
Placed at the high point in the lake, the weir will slow the normal flow of water to allow sediment to drop into that section of the lake, Bishop said.
During high water some sediment will flow over the weir and go into the lower portion of the lake, but the weir will cause the sediment to concentrate in the upper portion.
When the lake again collects a lot of sediment, city crews can concentrate on the upper area instead of the entire lake, thanks to the weir.
The lake is fed by two water sources: Pistol and Browns creeks.
Pistol Creek runs through the Greenbelt from behind the Blount County Courthouse and under East Harper Avenue before entering the lake. Browns Creek runs underneath Veterans Memorial Bridge and Parham Avenue before flowing into the lake.
Following construction of the weir, sediment will be removed from where the two creeks flow into the lake, Bishop said.
By the end of September the contractor should be wrapping up any tree and shrub planting and seeding of grass, Bishop said.
The project should be completed in October, hopefully in time for the Foothills Fall Festival, which will be Oct. 12-14.