Posted on April 20, 2021
The member municipalities comprise the Blair County area that is urbanized, and thus subject to the Municipal Separate Storm Sewer System, or MS4, mandates, which flow from the federal Environmental Protection Agency to the state Department of Environmental Protection.
So far, the dredging work is the committee’s biggest project, slated to reduce sediment runoff by 544,000 pounds per year by providing room for the lake once again to become a sediment trap for silt carried downstream by Brush Run.
The job required Hawbaker to cut a channel to allow Brush Run to continue sending water through the lakebed.
The channel hugs the Logan Boulevard side of the lake.
It appears to be a continuation of the natural channel of the creek, which runs along the back edge of Lakemont Park — although it’s uncertain where the original natural channel crossed the lakebed, which was probably not a natural depression, but rather dug out when the park was constructed, Shura indicated.
Workers are loading the mud into tri-axle dump trucks at a spot near the dam.
They are pushing the mud to that location with bulldozers, Shura said.
Based on an initial survey of the lake using density-sensing equipment, the dredging should remove about 36,000 cubic yards, Shura said.
That initial survey provided target depths for the contractor, whose equipment allows operators to meet those target depths through digital means, Shura said.
The project requires the workers to get rid of the mud down to the solid lake bottom, and the actual amount of mud will probably exceed the initial estimate, he said.
Hawbaker will be paid for that extra work, he said.
While not bedrock, the bottom is clearly of a different consistency than the fine silt, and it’s not hard for equipment operators to tell when they reach it, Shura said.
Workers have had to pause the digging after major rain events, because the lake fills up quickly, despite the diversion channel, Shura said.
The contractor has pumps on site to help speed the dryout, he said.
The water those pumps draw up is filtered through rocks before being sent into the channel, he indicated.
The project plan called for turtles found in the mud to be relocated safely, but to his knowledge, no turtles have been found, Shura said.
There was probably enough time between the initial drawdown and the commencement of dredging for the turtles to relocate themselves upstream, he said.
Dump truck drivers are taking the mud to four deposit sites in Antis Township, where the silt will be used eventually as reclamation cover, after the state removes a bony pile near Kerbaugh Road.
The site of that pile will become an adjunct recreation area for a trail that the township is constructing.
Because the silt flowed into the lake from a largely urban landscape, it is nutrient deficient, so workers will need to amend it with compost before planting grass, Shura predicted.
The contractor has asked for a time extension on the dredging project, although it’s likely it won’t be needed, Shura said.
An agreement the committee approved Thursday will allow the contractor to argue for such an extension — but also allow the committee to contest those arguments, said ISC solicitor Patrick Fanelli.