Tipping Fees Reach the Tipping Point - The Why, What, and How of the Summerville CPW Biosolids Upgrade Project

The Summerville Commissioners of Public Works (SCPW) operate a 10 MGD Wastewater Treatment Plant (WWTP) serving the Town of Summerville, South Carolina. Facing increasing biosolids disposal fees, in the late 2010's SCPW joined a consortium of local utilities developing a regional Class A biosolids facility. Concurrently, SCPW recognized the need to increase dewatering capacity and contracted with engineering firm KCI Technologies, Inc. to design a second belt filter press for the WWTP. Initial efforts convinced SCPW that a more comprehensive solution was required, so the engineer was tasked to develop a biosolids master plan to minimize disposal costs for the facility. This master plan concluded that installation of solar biosolids dryers at the WWTP would have the lowest lifecycle cost of the alternatives considered. With disposal costs around $53 per wet ton (WT), the engineer recommended a second belt press and digester improvements in the short-term but delaying solar dryers till disposal fees exceeded $90 per WT (projected to occur in 18 to 20 years). Within weeks of receiving the engineer's recommendations, SCPW was informed by the landfill operator that dewatered biosolids must meet certain compressive strength requirements or be subject to additional fees. Testing confirmed that SCPW's dewatered biosolids did not meet the strength requirements; as a result, SCPW's disposal costs doubled almost overnight to $110 per WT. Biosolids dried to 50% solids content were shown to meet the requirements. Based on lifecycle cost and time considerations, SCPW withdrew from the consortium and proceeded with design of solar drying facilities, which could achieve significant reduction in biosolids volume and reduced disposal fees due to meeting the strength requirements. The engineer evaluated the entire biosolids handling train to find a solution that minimized lifecycle costs. The evaluation showed that improved digestion and dewatering plus solar drying to 60% solids could reduce biosolids by over 85%. The engineer recommended aerobic digester improvements and new three-belt filter presses in addition to three solar dryer bays. In an atmosphere of skyrocketing construction costs and lengthening lead times, SCPW first selected the solar dryer equipment. After visiting and considering solar dryers from three manufacturers, SCPW selected a batch solar drying system from TPS Technologies. The selection process for other equipment was initiated pending a decision on project delivery method. During preliminary design, SCPW selected Construction Manager at Risk (CMAR) project delivery to maintain cost control and maintain the schedule. SCPW selected Harper General Contractors - Environmental Systems Division as the CMAR. With the CMAR on-board, selection and procurement of other major equipment was prioritized to minimize procurement-related delays. The CMAR made value engineering recommendations at various stages of design review, facilitated early procurement of major equipment, and provided Guaranteed Maximum Prices (GMPs) and schedule updates through the design process and into the construction phase. Construction of the biosolids improvements began in January 2023. To date, building and equipment pads have been constructed, the solar dryers are 90% complete, and digester equipment and belt press installation is underway. Startup is scheduled for March 2024. This presentation will discuss the factors affecting project scope, equipment selection, and project delivery from the perspective of the Owner, design engineer, and CMAR. Learn about: the market forces that combined to accelerate the project from a 'next 10 years' project to immediate implementation; the process of selecting and procuring major equipment; the considerations that led to the selection of CMAR delivery; the CMAR selection process; and the impact of CMAR project delivery on schedule and costs.