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Ms. Sue Polka June 2, 2017 Page 2 conducted in 1990, tank levels, pump operations, and flow conditions were not recorded and therefore not used in the model calibration. ORIGINAL MODEL APPROACH The Wenck model was evaluated to determine its ability to accurately predict domestic pressures and fire flow rates throughout the existing water distribution system. The following parameters were evaluated, and based on the results of the evaluation, were either confirmed or updated in the model. - Demand Allocation: Water usage demands were based on 2004 through 2011 metered data supplied by the City of Roseville. To verify existing water demands, the City provided metered data from 2005 through 2016 which confirmed the existing average day demands. For future water demands, MCES population projections along with the historic metered data were used to verify the future proposed water demands. Water demands for the TCAAP development site were verified using the 2017 MCES SAC Procedure Manual. - Peak Day Factor: Since the City is unable to record hourly and daily water usage with its existing control system, the average day to maximum day peak factor of 3.0 was verified by comparing typical maximum day peak factors that have been experienced in surrounding communities. - Watermain Transmission Lines: Existing watermain lateral lines were added or activated based on the overall Arden Hills ’ watermain map provided by the City. The Wenk model also featured proposed trunk and lateral watermains in the existing water system model, which were inactivated to accurately represent existing conditions. - Water Towers: There are two existing water towers within the City, totaling 1.5 million gallons of storage. The tower properties, such as tank size and overflow elevation, were provided by the City and verified in the Wenk model. - Booster Station Pumps: There are two booster pumps at the existing east side booster station. The pump performance curves associated with the booster station were supplied by the City, and WSB used the curves to update the model’s pump characteristics with efficiency curve points. - Controls: The Wenck model had the controls set-up to operate the existing booster pumps based on hydraulic gradients and pressures at water system nodes. To receive more accurate results of how the City’s water system is functioning, WSB redefined the pump controls to operate the pumps based on water levels within the City’s water towers. - Water Supply: The City’s water supply is provided by three interconnections with the City of Roseville. Since the City’s interconnections do not have automated meter readers to measure real time flows, the capacity of these interconnections are not known. Once the existing model was updated, the pressures and available fire flows from the model were calibrated using actual pressure and hydrant flow tests performed by WSB at various locations of the distribution system (see Figure 1). Seven hydrant flow tests were conducted and the results from the field testing indicated that the static pressures and available fire flows in the model are within 3 and 7 percent of the field testing data, respectively. This level of calibration is considered acceptable for use of the computer model in master planning. WSB MODEL RESULTS Following the calibration and update of the water model, the future water system was evaluated to determine its ability to provide water at adequate domestic pressures and adequate fire flow rates, particularly the extension into the TCAAP site. Pressure standards were based on water system domestic pressure standards as recommended by Ten States Standards. Fire flow standards were based on International Building (IBC) standards, upon which the Minnesota State Building Code is based. In addition, future water system improvements previously recommended by Wenck were reviewed,