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Silt buildup, aging pipes threaten Lake Knickerbocker
Drainage in Gainesville lake causes concern about flooding, dam stability
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An estimated 32,000 cubic yards of silt was found in Lake Knickerbocker in a survey completed about several years ago. The 4- to 5-foot layer spread across the bottom of the 45-acre lake has cut off inlets and contributes to potential flooding.

From the back of his truck, Randy Askea navigates an electric, four-wheeled vehicle with an attached camera through a decades-old pipe running under an earthen dam spanning East Lake Drive in Gainesville.

“We’re running a camera up the pipe to check the condition,” he said.

Askea, of Continental Pipe Services in Atlanta, expects to find vegetation clogging sections of the pipe, as well as signs of corrosion and leaks.

After all, this kind of corrugated metal pipe is no longer used in construction. Concrete has become the norm.

It’s possible this pipe will need to be replaced soon to help ensure the stability of the dam, which separates Lake Knickerbocker from Lake Lanier in this residential neighborhood where the Chattahoochee Golf Course is located.

The inspection performed Friday is part of a larger maintenance plan for the dam, which has prompted fear of collapse in the community as a result of silt buildup, inadequate drainage and overgrown vegetation.

The dam was constructed in the early 1950s, but its long-term integrity is in question.

Though a dive inspection performed on a drainage outlet in Knickerbocker identified no major problems, Askea questions whether the valve has proper overflow control.

Residents, led by David Gleason, president of the Lake Lanier-Knickerbocker Protective Association, have long complained about silt pouring into the lake as a result of inadequate drainage infrastructure and the emergence of new development in the area.

An estimated at 32,000 cubic yards of silt was found in a survey completed about several years ago.

The 4-to-5-foot layer spread across the bottom of the 45-acre Lake Knickerbocker has cut off inlets and contributes to potential flooding.

Myron Bennett, Gainesville’s engineering and construction division manager in the department of water resources, said maintenance repairs and improvements could include building headwalls, reducing flow and debris through the pipe spillway and developing a three-phase erosion, sedimentation and pollution control plan.

Bennett said he intends to protect the slope from the dam to a Lanier cove with rip rap, or a rock material, for erosion control.

Schnabel Engineering, based in Alpharetta, is developing a maintenance plan for the dam, which includes ideas for the proper of trees, stumps, roots and other vegetation from both the upstream and downstream slopes of the dam.

Askea said no vegetation should be growing on the dam because it compromises the earth itself.

Bennett said the city will likely send out bids for a construction contract to complete this work in the late summer or fall.

“Hopefully, we will not need the entire $1.8 million for the project, but that is what we have currently budgeted,” he added.

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