New Hanover County's biological treatment of landfill leachate provides treatment of up to 60,000 gallons of leachate per day, which is then discharged into a 0.6-acre retention pond and used for irrigation purposes rather than being released into the river. As the first of its kind within the state of North Carolina, the completed project will serve as a model for the solid waste industry worldwide.
The project was developed to meet New Hanover County Department of Environmental Management's goal to consider alternative, cost-effective, and long-term options of treatment of wastewater from the county's landfill. This goal resulted in a solution that relies on constructed wetlands for the treatment of leachate, the liquid byproduct of waste disposal.
This natural treatment process will ultimately eliminate treated wastewater from being discharged to the receiving stream by using it for irrigation on grassed, closed-out portions of the landfill—positively affecting water quality in the Cape Fear River Basin and protecting the quality of the delicate, coastal estuarine waterways. The 5-acre wetlands system helps to fulfill the long-term, landfill closure plan, which involves transforming the site into a wildlife park and habitat. In addition to the environmental advantages of using constructed wetlands for solid waste treatment, the project will serve the community years into the future, at a low operation cost.
CDM provided permitting support, design, and construction oversight of the wetland. A key strategy in development of the project was drawing upon the strengths of extensive pilot studies and research while deciding if a constructed wetland was a feasible plan and which type to construct. The county partnered with North Carolina State University, through grants from the N.C. Division of Coastal Management and Water Environment Research Foundation, to study five small constructed wetlands during the preliminary research phases of the project.