The Greenwood Metropolitan District is upgrading the Wilson Creek Wastewater Treatment Plant. As part of the work Metro is also upgrading a portion of the existing 30-inch Wilson Creek and 36-inch Coronaca Creek trunk sewers for this plant. Design South has been retained as the consultant for the improvements to the trunk sewer.

The proposed design includes installation of approximately 3,400 feet of sewer utilizing 72-inch HDPE pipe. Junction structures will be constructed near the confluence of the existing sewers to capture the wastewater flow from the existing 30-inch Wilson Creek and 36-inch Coronaca Creek influent lines. The proposed 72-inch HDPE sewer will reduce to the diameter of the existing sewers to facilitate the tie-ins. Provisions are included in the junction structures for future 60-inch expansion along the Coronaca Creek sewer and 48-inch expansion along the Wilson Creek sewer. Manholes for the project will also be fabricated from HDPE material.

The design for this project features installation of the pipeline in challenging conditions including bedding in very deep soils and also high groundwater levels. Use of HDPE as a large diameter trunk sewer will be a first for Design South and Greenwood Metro and could possibly be the first installation of its kind in the United States. The installation process includes electro-fusion welded joints that enable the pipeline to become a complete monolithic system. This process virtually eliminates inflow and infiltration into the sewer.