CC - Agendas - City Council - REGULAR - 7/10/2012

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EXHIBIT A City of Prescott 2012 Water Distribution System Model Update SCOPE OF WORK greater fire flows, or check valves from a lower adjacent zone that could open when needed to provide additional fire flows, although at a lower pressure. Capital improvements could include greater pumping capacity, increased looping, and larger main sizes. Priority will be given to making improvements for the greatest benefit for the expenditures that are made. A lower priority will be given to hydrants that are on cul-de- sacs or other locations where looping or other improvements may not be cost effective. Capital improvements that are specific to improving fire flows will be presented in the report to show the results of the fire flow analyses. 2.6 Uni-Directional Flushing Pilot A Uni-Directional Flushing (UDF) pilot will be developed using the modeling software and an add-on module licensed by Carollo. The UDF program will identify a sequence for water main flushing for a development or pressure zone that minimizes water discharges and water discoloration during the flushing event. Once prepared, the UDF program can be applied in an area repeatedly unless the water main configuration changes in significant ways. Results of the UDF program consist of a series of maps with an aerial photograph and water system infrastructure with specific instructions identifying which valves to close and which hydrants to open for each sequence. The City will want to ensure that distribution system valves are located and functioning properly before embarking on a UDF program. The City will be able to evaluate the benefits of a UDF program based on the results of the pilot. 2.7 Energy Evaluation The energy cost of the Prescott water distribution system will be evaluated to identify ways to reduce energy usage. The City will assist by providing operations information on pumps and also by providing insights into known inefficiencies and potential solutions. Carollo will use the tools available in the modeling software to benchmark the current energy usage. There are numerous characteristics of water distribution systems that contribute to energy inefficiencies, including but not limited to: • Incorrectly sized pumps • Worn pumps • Pumps that could be operated on different energy rate schedules • Excessive head losses • Improper PRV operation • Pressure zones that are configured without consideration of energy requirements • Pumps that could operate more efficiently on VFDs Carollo will systematically evaluate the water distribution to identify inefficiencies that may exist, and then provide recommendations to increase energy efficiency. Success of h:\bd_phx\prescott\water model update\prescott water model update project 06192012.docx 5