An on-campus water harvesting and reuse pond under construction on the Duke University campus in Durham, North Carolina, could supply up to 143 million gallons of harvested storm water per year — nearly 75 percent of the demand of one of the university’s centralized chilled water facilities — and save the university $400,000 annually.
The $14 million pond was designed by McAdams, a Durham-based infrastructure design firm, as part of Duke’s water saving and reuse initiative, reports Storm Water Solutions. Duke asked McAdams to identify sites for water harvesting and reuse in the wake of the historic 2007 drought, which affected most of the southeastern United States.
After identifying eight aboveground sites for drainage areas and potential runoff, McAdams ultimately identified the 256-acre water harvesting pond site adjacent to Duke’s Chiller Plant No. 2 for the project. The highly urbanized watershed of this site, along with the plant’s 2020 projected demand of 198 million gallons a year, provides a high-runoff, high-use site for the pond.
The final design includes a 20-foot-high dam, a pavilion with the intake structure, boardwalk, footbridge, pump house, amphitheater, outdoor classroom area and wetland and woodland plants. The pond will always have 8 feet of standing water with a reusable “flux” of 4 feet for storm runoff and use in the chiller plant (6.7 million gallons). The standing normal pool will provide almost 8 million gallons of emergency water storage.
As part of the pond project, McAdams designed and permitted 3,400 feet of stream restoration on another portion of Duke’s campus that ties directly into the university’s Stream & Wetland Assessment Management Park (SWAMP). A high water quality removal rate for nitrogen, phosphorous and total suspended solids was claimed for the facility.
Construction began in April 2013. The pond was filled in the fall of 2014 and will be fully functional this summer.