WCW24

A major current industry challenge is critical aging infrastructure being put under increasing pressure from growth through densification and catchment expansion, whilst also being asked to provide more for less with respect to capital and operational expenditure, without compromising mitigation of environmental and social impacts. This context creates unique and complex engineering problems like those presented on the Port Coquitlam Pump Station project. The pump station is the single point of collection and outlet for the City of Port Coquitlam with a catchment of 30 km2, a population of over 60,000, and bordered by federally protected salmonid and other fish bearing rivers. The station was constructed in 1976 along with the original forcemain, with a second larger forcemain built 30 years ago. The forcemains have significantly different hydraulic characteristics and profiles, including size, material, intermediate high points, and inverted siphon sections. Both forcemains discharge to an interceptor that experiences varying degrees of surcharge. The required capacity upgrade to address the projected growth exceeds the design of the current system, and as such the combination of these conditions lead to exceptionally complex system hydraulics. Jacobs was engaged to complete the engineering analysis and design for the system upgrade, whereby a combination of the existing forcemains are required to be used to obtain the necessary hydraulic capacity as the pipelines pass through sensitive environments and impacts must be limited. This task was further complicated as the original forcemain had been condemned due to poor condition and associated failures. Jacobs approached the problem incrementally: investigating and recommending specific rehabilitation for the original forcemain, completing field data sampling to establish the actual hydraulic characteristics of elements, hydraulic modelling to validate the field data and enable it to be extrapolated for the entire system, and complex holistic system hydraulics to determine possible system capacities under the wide range of operational and hydraulic scenarios. The complex hydraulics were key to understanding the problem and the solution. Analysis was completed via multiple methods to establish the steady-state upper and lower bound hydraulic conditions, the hydraulic envelope, and identifying hydraulic control points and transition regions. These envelopes and transition zones confirmed how the system could operate so the design could be completed to optimize system performance and assess how the system would respond under unplanned events such as hydraulic transients during a station power failure and what mitigation measures should be incorporated. This paper will present the engineering analysis completed by Jacobs with focus on the development and solution of the complex hydraulic evaluations associated with existing aging infrastructure. The analysis enabled Jacobs to select new pumps, design station upgrades and reliably recommend a system solution that provided exceeded the required capacity increase for the specified design horizon, but also future proofed the system for future capacity increases. This solution provided the optimal long-term solution considering capital and operational cost, adaptability for future changes and longevity of infrastructure, and mitigated environmental and social impacts, which is needed to address our industries aging infrastructure in the current climate.