Photos by Kyle Green | The Roanoke Times

Haren Construction Co. supervisor Phillip Wills (left) and foreman Don Waters watch as water is pumped out of an area of the Roanoke River near the city's Wasena Park. The company is tearing out a low-water dam and the sewer pipe inside it.

A piece of heavy machinery works at a Roanoke River construction site, where one expert says removing a dam will help reduce localized flooding and sediment buildup.

If you've been over to Wasena Park in Southwest Roanoke lately, you may have seen the bulldozers, earthmovers, giant pipe sections and an arc-shaped, strange looking contraption inside the Roanoke River that blocks much of the water flow.

It's all part of a $900,000 project under way to remove a small dam in the river, just upstream from the park, that has frustrated boaters and environmentalists for years.

The Western Virginia Water Authority, along with the city of Roanoke, the U.S. Fish and Wildlife Service and the U.S. Army Corps of Engineers are funding the dam's removal and a replacement of the old sewer line the dam encases.

Viewing the dam as an environmental hazard and a needless obstruction to river flow, federal and local agencies have sought its removal for more than 10 years, said Sarah Baumgardner, a spokeswoman for the water authority.

Located between Wasena Park and the former Hannah Court Trailer Park, the normally unused sewer line has been employed since the late 1990s to help prevent sewage overflows in weather emergencies.

Tennessee-based Haren Construction Co. began work this week to tear out the low-water dam and the 294-foot-long sewer pipe inside it. The company will install a similar diameter pipe below the riverbed.

New Jersey-based contractor Portadam Inc. spent four days last week installing a portable cofferdam system to divert water from the pipeline area so work can be completed.

Built with vertical steel supports that arc into the river and overlaid with a fabric covering, the portable dam shunts water away from the concrete dam. Workers have pumped out the water left behind the cofferdam so they have access to the concrete dam.

Among the project's benefits, the dam removal will help reduce localized flooding and sediment in the river, said Will Smith, a biologist for the U.S. Fish and Wildlife Service.

"Right now you have an obstruction in the channel which forces water to come up out of the channel. This increases the elevation of the water and can cause localized flooding," Smith said.

"The dam creates sediment buildup, which reduces the river's capacity to move floodwaters," he added.

Sediment buildup affects the endangered Roanoke logperch and other fish populations by cutting them off from their food source and preventing them from moving upstream and downstream, Smith said.

"The dam removal opens new habitat to the logperch and other species that is unavailable," said Marvin Moriarty, the U.S. Fish and Wildlife Service's northeast regional director. "This will open 185 miles of river and stream habitat for fish and wildlife." That distance includes the lengths of both upstream forks of the river, as well as tributaries that feed those.

The dam removal and pipeline replacement are part of a much larger $64.3 million flood-reduction project that has been ongoing for years along the Roanoke River through the city.

As part of that effort, contractors have created bench cuts along the river's winding path through Roanoke. A nearby, though unrelated, project also under way is clearing Hannah Court. It will become the latest addition to the city park system and perhaps a part of the Roanoke River greenway.

Boaters are excited about the dam's removal, said Bill Tanger, chairman of Friends of Virginia Rivers. Over the years they've dreaded the hassle of having to portage around the 5-foot-tall structure, he said. "The removal should improve recreation on the Roanoke River and make this city a better place to live," Tanger said.

The project has to be completed and the cofferdam removed from the river by March 15, the beginning of spawning season for the endangered logperch, said Greg Reed, engineering director for the Western Virginia Water Authority.