Lake Manatee Dam repairs under way

skennedy@bradenton.comApril 28, 2014 

MANATEE -- The Lake Manatee Dam is bristling with boats and other equipment and crawling with workmen and divers, as a $15 million emergency repair project to strengthen its core shifts into high gear.

"It's like a city down there now," said Bruce MacLeod, superintendent of the Manatee County Water Treatment Plant, during a tour Friday, gesturing to heavy equipment that has sprouted atop the East Manatee dam.

Already in place is a Trench Remix Deep machine, which will cut 105 feet down through the dam to inject a soil-cement mix. Workmen will install a new "cutoff wall" in front of the original one, which engineers concluded was eroding and seeping water, said MacLeod.

A cutoff wall is a barrier of impervious material built into the foundation of the dam to control seepage under it.

The TRD machine is so large it was necessary to build a platform for it before work could begin, MacLeod said.

Another large piece of equipment called a Jet Grout machine will inject a mixture of soil and cement designed to harden into columns, he said.

"Instead of a wall, it builds columns of soil-cement," he said.

County engineering consultant, AMEC Environmental & Infrastructure, recommended Hanover, Md.-based Hayward Baker Inc., a company specializing in geotechnical construction, as project contractor.

"The company's proprietary TRD cutoff wall construction method is

the desired method ... based on technical and safety concerns," wrote AMEC engineer Jeffrey Beriswill in a March 31 letter.

He said the London-based company, with a Tampa office, had taken the initiative to quickly mobilize "in order to meet the extremely accelerated project schedule."

County utilities officials said "re-establishment of the core in the highest priority area is deemed necessary by our engineer before a significant flow, such as typically can occur after four to five days of heavy rain, can be safely passed through the spillway," according to a letter dated March 31.

Officials are keeping the lake at about 38 feet deep rather than the usual 40 feet, as a precautionary measure.

MacLeod said he expected to finish the most crucial part of the project before Florida's rainy season starts in June.

About 50 workers are employed on the project, estimated Vince Hull, Hayward Baker senior project manager.

The Manatee County Commission earlier this month ratified a $14 million contract price for improvements but a budget amendment, including design services, came to $15.1 million, which will be paid out of county utility system reserves, according to county records.

The utility system's water treatment plant at 7914 Waterline Road provides drinking water to residents of Manatee County, Sarasota County and some residents of Bradenton and Longboat Key, said MacLeod.

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