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Between a Tree and a Hard Place: Public Involvement in Sewer System Planning
Author: Christopher D. Wilson; Alexandra Jones (Orange Water and Sewer Authority)
Date: 5/107
From the WEF Collection Systems Specialty Conference, May 2007

The Orange Water and Sewer Authority (OWASA) is the water and sewer service provider for the areas of Chapel Hill and Carrboro, North Carolina. In the heart of Chapel Hill lies the University of North Carolina-Chapel Hill (UNC-CH) also serviced by OWASA through parallel 18-inch sewer mains referred to as the Meeting of the Waters Interceptor (MWI). These pipelines dating back to the 1940s were laid adjacent to the Meeting of the Waters Creek and continued downstream to the Mason Farm Wastewater Treatment Plant (WWTP). The MWI travels along the edge of a large property that was subsequently set aside by its owner, William Coker, for the University and made part of the North Carolina Botanical Garden (NCBG). This land was called the Coker Pinetum and is a valued part of the University’s plan for protecting forested areas and significant trees. Downstream of the Coker Pinetum, the MWI runs along small local roads and then adjacent to the northern edge of the main NCBG property to the WWTP. Through recent master planning efforts for OWASA and UNC-CH, the existing 18-inch pipes of the MWI were identified as having insufficient capacity to convey future peak flows as the University continues its $1 billion expansion. Initial study recommendations suggested that replacing the aging clay pipes with a new single 36-inch ductile iron pipe would address the capacity issue. At the same time, OWASA was implementing a project to supply reclaimed water from the WWTP back to the UNC-CH campus for use in a variety of applications through a new 24-inch pressurized reclaimed water transmission main. These two projects would likely follow a similar route from the campus to the WWTP. Review of the natural topography of the area showed that the existing route along the Coker Pinetum was the only available corridor to allow gravity flow. OWASA staff presented the project to the local community in a public meeting to inform them of the issues and gather input. The NCBG staff and local residents, many who take personal interest in their adjacent forest, were concerned about the impact to the trees, creek, and disruption to the local roads of the adjoining neighborhoods. OWASA staff used the public input and implemented an Alternative Evaluation Project. Brown and Caldwell was retained to investigate various project alternatives (including construction of a new pump station to avoid piping through the Coker Pinetum area) using a Pairwise Comparison process. After developing a life-cycle cost analysis, investigating existing easements, preparing a thorough tree survey, and identifying pump station site requirements, the results were presented to the community. Using a thorough evaluation process and continuous communication with the local stakeholders, a project consensus was developed that OWASA is optimistic can be carried successfully through construction. This paper will review the decision-making and public involvement process and describe the challenges and accomplishments of the project.