Sam Ziemann From - Region of Waterloo

August 26, 2011Sam ZiemannPage 6 of 12Reference: Fluid Transient Analysis for Strange Street Raw Water Supply System – Draft TechnicalMemorandumthe Data Collection section. The model was then opened in Bentley Systems HAMMERtransient analysis software and saved.The following assumptions were made during model construction:• The Multiple Point pump type pump definitions provided in the model fromthe Kitchener Office were used in the transient analysis model. Thesedefinitions are based upon the pump curves.• A water elevation of 333.79 m was used as the downstream boundarycondition for the Strange Street Reservoir.• The following Hazen-Williams C-factors were used for watermains in themodel: 100-120 for CI and DI watermains; and 150 was used for high densitypolyethylene (HDPE) and PVC watermains.• Flow control valves were added to the model at each well to limit flows to therates provided in Table 1.• No air valves are installed on the Strange Street Water Supply System thathave the ability to allow air to enter the pipeline to prevent vacuumconditions.• Since the timing of well starts and stops was not provided, it was assumedwell starts occurred over a 5-second period and pump stops wereinstantaneous and the same as a power failure induced pump trip. Theseassumptions were made to estimate worst-case transient conditions withinthe raw water supply system.• The future raw water storage tank will be constructed at the Strange StreetReservoir site.• Operating pressure information was not provided. Therefore, the model wascalibrated based upon flow using the capacities within Table 1.Results for the water supply system indicate hydraulic conditions within the systemtransition from pressure to gravity flow approximately 1,150 m west of the GlaskowStreet/Belmont Avenue intersection. Therefore, a pressure sustaining valve was addedat the location where flow conditions transition from full pipe/pressurized flow to partiallyfull pipe/gravity flow to maintain pressurized flow upstream of this point. As shown inFigures 1 and 2, the slope of portions of the raw water supply system mains exceedsthe slope of the hydraulic grade. This will result in gravity flow conditions along portionsof the raw water supply system downstream of the pressure sustaining valve location.Figures 1 and 2 illustrate the hydraulic grade calculated by the model along the raw