Ugh, Not Another Forcemain High Point

Owners, engineers, and operators that are involved with wastewater forcemain systems often neglect the importance and associated risks of intermediate high points. This paper outlines the hydraulic-related challenges with intermediate forcemain high points and provides examples of the full suite/range of typical design solutions that are often considered and/or employed during design. The potential solutions are discussed from the point of view of challenges and risks, with the ultimate conclusion being that intermediate forcemain high points are a significant design challenge that is often not solved in a clear or proven manner. Given that many wastewater forcemain systems with an intermediate high point experience operational challenges, the paper also presents an additional and seldom considered design alternative of inline booster pumping for wastewater. The paper outlines the benefits and risks of inline booster pumping and proceeds to present a case study for a conceptual wastewater forcemain system with four inline booster stations to address the associated high static head, long length, and challenging intermediate high points. The case study initially provides an example of the hydraulic-related differences between inline booster pumping and traditional design with wet wells, including pump selection and surge protection requirements. The paper then proceeds to demonstrate how proportional integral derivative (PID) control logic for inline booster systems can be optimized with hydraulic transient modelling of pump operation and flow control stability. Overall, the objectives of the paper are to re-emphasize the challenges with intermediate forcemain high points and to discuss the potential benefits and risks of inline booster pumping as to promote discussion.