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October 5, 2011

Duck River to be built using roller-compacted concrete

By Trent Moore The Cullman Times

CULLMAN — After months of study, a decision has been made: the Duck River dam will be built using the relatively new roller-compacted concrete method. Officials hope the move will lead to a faster construction schedule and smaller environmental footprint as the project prepares to move forward.

Engineers with CH2M Hill — engineer of record for the reservoir project — have spent the past several months comparing the construction style with the more traditional earth-fill rock dam approach.

The Cullman Utilities Board had originally planned to build an earth-fill dam when the permit was approved by the U.S. Army Corps of Engineers in the mid-1990s. But, with the project stalled in lawsuits and appeals for more than a decade, dam construction evolved. In the years since, roller-compacted concrete became more common and officials wanted to research the potential advantages before starting work. Approximately 24 roller-compacted structures have been built in the southeast United States.

“We looked at a lot of things, critical issues and tangible issues,” CH2M Hill engineer Steve Newton said. “This is compatible with the permit and we think it will be very positive. This should help protect water quality downstream during construction and allow us to drastically decrease our footprint during construction.”

The roller-compacted design will allow the dam intake to be built in the center, whereas the old design had the intake about 100 feet away in the lake.

“From a maintenance standpoint that will be a lot easier, so you can drive right up to it,” Newton said.

Once the utility board’s dam permit cleared its last legal hurdle last year, project manager Dale Greer said officials wanted to consider every option before ramping up. Greer said the new method has caught on regionally and should offer some clear advantages to the older methods.

“Roller compacted concrete wasn’t prevalent until around the mid-to-late 1990s, so once the permit was clear we wanted to look at it,” he said. “That has a lot of benefits including a smaller footprint for the dam and less of an environmental impact. It has some advantages over a pure earth dam. It should help us with faster construction.”

The utilities board has made significant headway in land acquisition, with nearly two dozen of the 82 required parcels purchased or somewhere in the closing process. Appraisals have been completed on more than 75, and relocation specialists are working with the approximately 18 residents who will have to move for the dam’s construction.

“Those will be ongoing and typically start up after the closing,” property acquisition coordinator Mandell Tillman said. “But, overall, things are moving along rather quickly and we don’t see anything that should delay us at all.”

Plans to create a watershed management authority to eventually take ownership of the reservoir is still ongoing, and officials are testing the viability of starting construction with the utilities board as the main organization in charge. Greer said the board is still working out the logistics of how to eventually share ownership of the lake via a watershed management group, as board members have previously stated they would do.



* Trent Moore can be reached by e-mail at trentm@cullmantimes.com, or by telephone at 734-2131, ext. 220.

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