Engineers continue to review the design specifics of the Duck River Dam, after additional survey work in recent months found more clay at the construction site than engineers had anticipated.

The Cullman utilities board, with the cooperation of Cullman County and other area water systems, is creating a 640-acre lake with a 32-million-gallon-per-day capacity in northeast Cullman County. The dam will be approximately 2,000 feet wide. Once complete the lake will be used in conjunction with the area’s sole water source, Lake Catoma.

The design team at engineer-of-record CH2M Hill is expected to spend the next few months taking a close look at the hybrid earth-fill/roller-compacted concrete dam design to determine how it will need to be adapted to fit the site.

More detailed excavation of the site found that the original design would not work because of the bedrock and soil layout, which has led the engineers to pause and make changes.

The cost was originally anticipated at approximately $68 million, though it could increase once engineers retool the design.

Restricted covenants, required as part of the permit with the U.S. Army Corps. of Engineers, have been filed for the project, meaning construction can now begin in the streams in the watershed. The covenants only apply on the property owned by the city.

“The number one thing with having that complete means that ‘construction’ can begin, which actually means being able to work in the water,” Steven Newton, with CH2M Hill, said. “That’s a good thing to have in place because it restricts future use and serves basically to protect the water source.”

While the design is being reviewed, the utilities board has asked phase-one excavation contractor Brasfield & Gorrie to move ahead with ancillary work on a diversion around the dam structure site. Contractors will begin rock blasting soon and remove the west bank to accommodate equipment to install the concrete pipe.

The recreation plan at the dam site is also moving forward, and engineer Bill St. John said they currently anticipate installing nine-and-a-half miles of walking trails around the lake.

“That’s something we think will attract people to Cullman as part of this project, and we want to bid it out in the middle of July,” he said.

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