Utility Merger Enables Scalable Redesign of a Regional Lift Station

As communities grow and regionalize, wastewater infrastructure must evolve to keep pace with increased demands, development pressures, and long‑term planning needs. This presentation explores how the project team and TriRiver Water transformed an undersized, decade-old lift station and force main design into a regional and scalable system. This project revisits a lift station and force main originally designed in 2014 to divert flow from an overburdened 0.75‑MGD treatment plant. The initial design, developed to convey a 3‑MGD peak flow, underwent several years of permitting, stakeholder coordination, and funding adjustments before bid results in 2022 exceeded the available budget. Meanwhile, growth within an 8,500‑acre master‑planned development progressed quicker than anticipated, and updated projections indicated peak flows of 12.5 MGD. With these conditions in mind, the team redesigned the system to better reflect regional needs, operational realities, and opportunities for long‑term scalability. The team's objective was to create a more flexible and cost‑effective system while working within existing permit constraints and time‑sensitive funding requirements. At the time redesign began, the project held multiple active permits. This required close coordination with regulators to adjust the design without resetting the entire permitting process. Updated hydraulic evaluations optimized pump configurations for both near‑term and buildout scenarios. System limitations included a total dynamic head limit of 400 feet, a pump horsepower threshold of 500 hp, and maximum velocity targets of approximately 8 ft/s. These analyses helped define feasible pipe diameters for the 13‑mile corridor. Value engineering and several other considerations shaped the design direction. Constructability was a large focus during value engineering addressing issues such as deep excavations and numerous horizontal directional drill locations along US‑15/501. HDPE was selected for its lower cost and flexibility which reduced the need for fittings and appurtenances. Operator input played a significant role in refining the wet‑well layout, ensuring future pump slots could accommodate dry‑pit installations and that SCADA integration supported regional operations. Phasing options were also evaluated to help manage funding cycles, maintain service during construction, and provide a clear pathway for future expansion. These options included evaluation of proposed intermediate lift station and parallel force mains to support regional buildout. Bid tabulations from the redesign confirmed that a 36‑inch force main delivered the best balance of cost, performance, and expandability. Although the 24 inch force main provided a cost effective near term solution, the 36 inch pipe offered several advantages. Most notably, it provided the full buildout capacity in a single capital investment and installation, eliminating the need for a future parallel 24 inch force main. Installing two 24 inch pipes would increase total material and construction costs over time and require the utility to reopen the corridor introducing additional environmental impacts and extended traffic disruptions. This redesign demonstrates how the team transformed a constrained, over‑budget design into a resilient, scalable regional solution through hydraulic flexibility, practical constructability reviews, and sustained regulatory engagement. The insights gained offer valuable guidance for utilities facing similar challenges associated with growth, permitting, and evolving operational needs.