|E.L. Smith Water Treatment Plant Expansion Low-Lift Pump Station and Fish Return System CFD and Physical Model Studies|
CLIENT: City of Edmonton
NHC constructed and tested a 1:6 scale physical model for the proposed low-lift pump station and fish return system for the E.L. Smith Water Treatment Plant Expansion Project in Edmonton, Alberta, as a sub-consultant to Associated Engineering Alberta Ltd. The pump station will be symmetrical about its centerline, with each half housing a pump sump forebay area with four travelling screens, two low-lift pumps, and a fish return system. Each half of the pump station will have a capacity of 505.5 mega litres per day.
CFD analyses of the proposed intake structure were undertaken by NHC in order to improve performance within the pump sump forebay, with respect to hydraulic and fisheries perspectives. CFD modeling resulted in a significant reduction in cost and time required for model construction. The low-lift pump bay was shown to be susceptible to elevated levels of flow pre-swirl, subsurface vortex activity, and temporal velocity fluctuations at the pump impeller location. Recommended modifications to the low-lift pump bay included installing a false backwall, a raised floor, sidewall and backwall fillets, and a center floor splitter beneath the pump bell inlet. With these modifications installed, all of the pump intake performance criteria were within acceptable limits for the range of operating conditions examined in the model.
In addition to those modifications made during CFD modeling, NHC recommended modifications to the pump sump forebay included re-aligning the travelling screen structures, revising the entrance geometry of the fish return pump bay, and increasing the overall discharge of fish return pumps to increase the velocities at the pump bay entrance.