The Richland Creek dam was built in 1970 to create a standing pool of water that the adjacent public golf course could draw from for irrigation. Nearly 35 years later, the Metropolitan Government of Nashville & Davidson County (Metro) partnered with non-profit Cumberland River Compact (CRC), The Nature Conservancy and KCI to remove the small structure as part of a Tennessee Department of Environment and Conservation Aquatic Resource Alteration Permit. This project was the first of its kind in the area and one of only a handful in the state.
Dam removal is becoming more common in promoting aquatic organism passage, alleviating the risks inherent in aging or compromised structures, and addressing ongoing maintenance expenses incurred by dam owners and operators. The Richland Creek project also had the potential for marked ecological benefits within the stream.
“We’ve found so many of these dams that are undocumented and un-inventoried, and they have a big impact on some of the aquatic species and also on water quality,” said CRC Executive Director Mekayle Houghton.
KCI environmental scientist Adam Spiller initiated a feasibility study to identify constraints, challenges and potential costs to remove the structure. “During the first phase of the project, the sediment that had built up behind the dam was a big unknown,” he said. “There was a question of how much and whether it was contaminated.” Through sampling and testing, the KCI team determined that the sediment was not contaminated and that the project could move forward.
The primary design constraint revolved around the need for a permanent pool of water adequate for withdrawal in the absence of the dam, while mimicking natural channel diversity upstream and through the project area. “The regulatory agencies and a local watershed group had voiced concerns over using a traditional boulder vane structure because they perceived the approximately six-inch high steps over rocks as potential barriers to movement of aquatic organisms,” said Spiller. “Instead we designed a constructed riffle/constrictor that uses boulders and native stream sediments that had been impounded above the dam to create a structure that is more natural in appearance while still providing interspersed refuge areas that are better suited for fish and other species passage.”
Open lines of communication are key to expediting any dam removal project to address all concerns and questions, provide information needed to properly inform the public and build grass roots support.
Adam SpillerRegional Practice Leader, Senior Environmental Scientist
The adjacent golf course posed additional challenges while it also offered opportunities for cost management. Materials and equipment had to cross multiple fairways and cart paths to reach the project location. KCI worked with the Metro to utilize their vehicles and staff in hauling rock and concrete to and from the dam site. Using city resources as well as their contracts with local quarries offered Metro a level of comfort with regards to protection of their property while also reducing the overall construction costs.
By using a modified design-build approach, KCI was able to keep tight control over the budget and schedule. Construction commenced only two days after permits were received and was completed within two weeks. “If we had to go through bidding and coordination with an outside contractor, we could never have been that efficient,” said Spiller. From feasibility to final punch list, the removal took just over one year, with a total project cost of only $69,000.
“There is such instant gratification,” said Houghton. “KCI took the dam out and the same day you saw riffles in the stream where there had been cool stagnant water.” CRC was able to demonstrate commitment to their mission and community with a very visual and quantifiable improvement to the watershed, while capitalizing on publicity and positive feedback that they plan to leverage into beneficial opportunities.
The project has helped pave the way for more dam removals in Tennessee by proving that regulatory and construction phasing concerns can be overcome with a shortened project life cycle, streamlined permitting process and by using and adapting existing techniques. As the engineering community moves forward with future dam removals in the region, Richland Creek will serve as an example of sound engineering, efficient construction, effective public outreach and a solid working relationship among the stakeholders. In March, the American Council of Engineering Companies of Tennessee recognized the Richland Creek Dam Removal with a Grand Engineering Excellence Award in their small projects category.