Precast concrete weir helps create a storm water wetland in North Carolina
There are a number of ways to collect, manage, move and process storm water runoff. Some systems detain storm water to control its release, some filter it to provide a cleaner end product and some even find a beneficial reuse for it. The city of New Bern, N.C., set out to accomplish all three of those goals and more when it partnered with the N.C. Ecosystem Enhancement Program and the N.C. Clean Water Management Trust Fund.
Together, they created a storm water wetland designed to capture and treat runoff from more than 1,000 acres of developed land. The benefits of the project are numerous. To start, the wetland retains water that would otherwise flow to the Neuse River. In doing so, it allows the storm water to percolate and use the natural filtration properties of the earth before it becomes groundwater.
While the water remains on the surface, it creates a habitat for a wide range of wildlife and also provides a research area to study the ability of the wetland to improve water quality.
The contractor turned to Cape Fear Precast to manufacture a weir that would typically have been a cast-in-place structure to create the wetland. By partnering with Cape Fear Precast, the subcontractor met the parameters for lifting capacity and time constraints. The precast option enabled the subcontractor to shave two weeks off the onsite schedule while meeting the quality requirements of the project engineer.
Design and manufacture of the weir to meet lifting capacity constraints included casting a two-part base slab that was bolted together on site and nine units to create the vertical wall. The shape of the weir creates a stable configuration and allows water level control through the use of flashboard risers. The legs were preassembled at the precast plant and shipped with a custom spreader bar for handling. The installation took approximately four hours and all seams were sealed with elastomeric sealant and bolted together with galvanized hardware.