Lake Manatee Dam repair continues despite early rains

Lake Manatee Dam repair continues despite early rains

skennedy@bradenton.comJune 1, 2014 

LAKE MANATEE DAM

Work is continuing on a $15 million emergency repair project at the Lake Manatee Dam, although the early arrival of summer rains has posed a challenge, officials said.

On Memorial Day, some parts of the property were inundated with 2 inches of rain, which slows the pace, said Bruce MacLeod, superintendent for the Manatee County Water Treatment Plant, operator of the dam and the Lake Manatee Reservoir.

Rainy season arrived three weeks early this year, he noted.

"It slows it down," he said. "They work through the rain, but if there is lightning, they get off the dam."

"We may be a little behind schedule," he said Friday, but predicted the project would remain close to its original timeframe.

"If we do fall behind, it's only enough where we'd be able to catch up," said Amy Pilson, public affairs liaison for the county utilities department, which supplies drinking water to customers in Manatee and some areas of Sarasota County.

Jet grout crews Wednesday upped their hours from six days a week, 12 hours a day, to six days a week, 24 hours a day, according to a status report written by Mike Gore, county utilities director.

The jet grout machine injects a mixture of soil and cement that hardens into columns to provide stability to the dam in East Manatee at 17915 Waterline Road.

Engineers may have to redesign part of the project after crews discovered a 160-foot row of sheet pile

running along the north-south axis of the dam, near the old river channel, Gore's report said.

"It was something unexpected," said MacLeod.

Friday, a Trench Remix Deep machine, which cuts 105 feet down through the dam to inject a soil-cement mix, had been moved from the dam's south side to its north side.

"The TRD machine was on this side, and the jet grout on the north side," explained MacLeod. "They finished jet grouting on the north side of the spillway, and now are on this side."

In February, officials announced the dam may have been compromised by erosion, and they slowly brought lake levels down from 40 feet to 38 feet as a precautionary measure. Workmen are installing a new "cutoff wall" in front of the dam's original one, which engineers concluded was eroding and seeping water.

A cutoff wall is a barrier of impervious material built into the foundation of the dam to control seepage under it. The county utilities staff and its engineer of record, Carollo Engineers Inc. of Sarasota, along with a consulting firm, AMEC Environmental & Infrastructure Inc. of Tampa, developed stabilization plans, and chose Hayward Baker, Inc., of Tampa, as their contractor.

Sara Kennedy, Herald reporter, can be reached at 941-745-7031. Follow her on Twitter @sarawrites.

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