DESIGNING ONE OF NORTH CAROLINA'S LARGEST SEWERS – TECHNICAL CHALLENGES AND COMMUNITY ACCEPTANCE

Charlotte-Mecklenburg Utilities (Utilities) currently operates five wastewater treatment plants (WWTPs) with a combined wastewater treatment capacity of 118 mgd. The Sugar Creek WWTP treats wastewater from a portion of downtown Charlotte and south Charlotte within the Little Sugar Creek and Briar Creek drainage basins. The existing Briar Creek trunk sewer was constructed of vitrified clay pipe (VCP) in the late 1920s, and the condition and capacity of the existing sewer does not provide the level of service required by Utilities, new state laws, and EPA. Therefore, improvements are necessary to reduce the risk of sanitary sewer overflows and to increase the sewer capacity to meet current and future wastewater flows. The Briar Creek Relief Sewer will replace most of the 1920s sewer and is designed to convey 75 mgd. Phase I of the project consists of more than four miles of 72-inch and 60-inch diameter sewer that will tie into a new pump station at the Sugar Creek WWTP, which is currently under construction. Two additional phases are being designed and will be constructed in the future.When the proposed design of the new relief sewer was introduced to the public, there was significant public opposition. Since the Briar Creek basin is primarily residential and nearly built out, the sewer route was located though many wooded backyards and in some areas within 25 feet of homes. In addition, the sewer would be constructed through a park-like school campus, a prestigious golf course and country club, neighborhood association properties, a land conservancy, high-end apartments, and a neighborhood park. Because of the vocal public opposition and concern over the project, a proactive public communication and outreach program was developed that gave property owners multiple opportunities to provide input. As a result, the route was realigned to reduce impacts to residential properties by 50%. In addition, many other route adjustments were made to minimize disruption through public and commercial properties.Because of the size and location of this sewer, substantial construction constraints also exist. Some of the constraints include installation of the new relief sewer adjacent to an aging VCP sewer which must remain in service during construction, limited construction space because of the highly developed area, depth of construction ranging from 25 to 60 feet, and scheduling restrictions.As a result of the proactive public communications program, public opposition has been significantly reduced, and 62 of the 63 easements for the project have been acquired. All of the regulatory agencies have issued the required permits, and the project was advertised on March 2, 2007.