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Duck River project cost placed at $21M

Wednesday, April 30, 2008

With one eye on the current drought and the other eye on future flooding, the Tennessee Duck River Development Agency will soon be requesting feasibility studies for solutions -- one of which could be raising the pool level at Normandy Dam 5 feet -- which would mean construction work to raise the actual dam and replace the spillway gates.

Mike Eiffe, program manager for water quality at TVA, gave the DRA a short resentation Thursday night during a work session at Henry Horton State Park.

"In 2000, TVA completed a programmatic environmental impact study (PEIS)," said Eiffe.

The purpose of the study, he added, was to research ways to increase the water supply for the upper Duck River watershed, and the estimated cost at that time was about $8 million.

The estimated cost of the project Eiffe gave the board Thursday was closer to $21 illion, but he said there was a still a lot of uncertainty in that final number.

The breakdown of the project included:

-- Cost to raise the dam, $5.03 million

-- Modification of spillway gates, $3 million

-- Modification of roads, $ 5.6 million

-- Modification of bridges, $5.5 million

-- Land acquisition, $520,000

-- Environmental impact study, $1.3 million

While TVA was fairly confident in the costs for raising the dam and modifying the gates, Eiffe said the other costs required more study, especially the bridges. If the bridges can be raised without having to replace the basic structure, he said, that would bring the cots down.

In the original 2000 study, it was thought that simply reinforcing the spillway gates and strengthening them would suffice, but Eiffe said they would have to be replaced.

Raising the pool level five feet would require purchasing about 52 acres of land that TVA doesn't already own in a narrow strip around the lake.

"It's mostly woodland," said Eiffe. "We're not talking residential here."

TVA looked at other options, including simply raising the winter pool level one foot. Eiffe displayed a graph that showed by increasing the winter pool level just one foot, the possibility of future flooding increased dramatically -- especially in Shelbyville.

Other structural possibilities were also mentioned, including a dam at Fountain Creek, a pipeline from Tims Ford to the Duck River and a pipeline from the Tennessee River below Columbia to Columbia.

At the board meeting later that night, a motion to request proposals for feasibility studies for:

-- Increasing storage at Normandy Reservoir

-- A pipeline from Tims Ford Reservoir to Duck River

-- A reservoir in the Fountain Creek Watershed

Additional alternatives should be considered in the study, the motion read, such as a pipeline from the Tennessee River, waste water plant upgrades or other infrastructure projects for regional water supply.

"We're capable of making a decision now," said Doug Murphy, executive director for DRA, at the work session. "But we may not have all the information to make a good decision."