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• mimmai gravity storage <br />• VFDs and steady state pumps pumping directly <br />into the system, and pressurizing <br />• Results in a hydraulically sensitive system, where <br />small changes in system operations create wide <br />variations in system pressures and flows. <br />Based on IDM's experience with similar systems, it is <br />recommended to increase the resolution at which <br />this model operates, to 15- minutes. This will <br />increase the accuracy of calibration and significantly <br />improve model convergence for the life of this <br />hydraulic model. More details below: <br />• Create diurnal demand patterns with 15- <br />minute Intervals, over the course of the day. <br />Typical diurnal demand patterns are 1 -hour. <br />• Use a hydraulic time -step of 15- minutes for <br />model simulations. This will catch fluctuations <br />in system operations and allow for more <br />accurate calibration and analysis. <br />• Adjust model tolerances and relaxation <br />factors as necessary to support model <br />convergence. These parameters can be <br />reasonably adjusted within the modeling <br />software to support convergence for <br />hydraulically sensitive or complex models. <br />The following efforts are proposed based on IDM's <br />experience calibrating hydraulic models for systems <br />of similar size and configuration, in addition to <br />accounting for the City's intended uses for the model: <br />1. The calibration goal of this Project is to achieve <br />results within 3 feet and same trending for all <br />storage tanks, and 15% for all flows and 10psi for <br />all pressures from pump stations, pressure <br />regulating stations, and inter - agency connections. <br />2. Identify the calibration period, system demands, <br />and demand allocation. To capture dynamic <br />system conditions, IDM recommends focusing on <br />data within the maximum demand we_... <br />v. unuze geocooeu oemanas iur the moues uy <br />globally factoring up or down to match the <br />system demands identified for the calibration <br />period. Note that diurnal curves developed for <br />this Project will further adjust hourly demand. <br />5. Perform preliminary simulations to compare <br />model output to SCADA data for tank levels, <br />pump station flows and discharge pressures, <br />pressure regulating station flows and pressures, <br />and inter- agency connection flows and pressures. <br />6. calibrate the model by potentially modifying <br />operational controls, pump settings, pump <br />curves, diurnal curves, and pressure regulating <br />valve settings based on SCADA data, operations <br />manual, and operator experience. <br />Any differences between the hydraulic model and <br />field readings will be documented and <br />recommendations made for resolutions. Sources for <br />discrepancy with the field may include: field sensor <br />calibration, inaccurate field reading, unknown <br />