Large Pump Station Rehabilitation: Temporary Bypass System Design is Key!

Across the nation there are massive rehabilitation and construction projects under way or in the planning stages to remediate aging water and wastewater piping and pumping systems. These systems must continue to operate to convey the water and wastewater flows to their intended destinations. The systems used to temporary bypass the pumping systems and portions of pipelines have often times become the weak-link in the rehabilitation process. The design and construction of temporary bypass pumping systems is a critical component in these rehabilitation projects and more focus should be taken by the design engineer in the development of these systems as opposed to obligating this responsibility to the Contractor. Bypass pumping holds a potential for spills, overflows, and detrimental contamination of sensitive ecosystems that can have long-term adverse impacts to the environment and the community. Although the Contractor is ultimately responsible for the installation and operation of the bypass system, specifying an engineered approach in the contract documents offers many benefits, including an evaluation of pumping in multiple scenarios, providing a basis of design for bidding, providing, and setting minimum criteria for construction. This paper focuses on developing design criteria for the bypass systems and will provide case studies of bypass systems designed and installed for pump station rehabilitation. Lessons learned from these installations will also be presented. The paper evaluates the elements required to implement a successful bypass system during a large pump station rehabilitation project, including: 1.Designing an efficient system with sufficient redundancy for average and peak hour flows, including pump size, capacity, and number of each size to be onsite 2.Designing severe wet-weather capacity needs 3.Identifying optimal location of pumps, piping, and fuel storage for safety and potential conflicts 4.Protocols for system startup and decommissioning 5.Developing automated equipment and communication protocols to avoid overflows 6.Remote monitoring and control of pumps using SCADA integration 7.Regular maintenance of bypass equipment The case studies include an evaluation of two JEA (located in Jacksonville, FL is the largest utility in Florida and the eighth largest in the nation) bypass pumping systems for two major pump stations rehabilitation projects: 1.Buffalo Ave Pump Station: 7 MGD, triplex bypass pumping system (Operational from April 2020 to April 2021) 2.118th St Pump Station: 21.5 MGD, quadraplex bypass pumping system (Operational from June 2022 to July 2023)