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 1.2 Facilities Updates The City is currently in the process of updating the GIS data layers with new infrastructure and projects that have been completed. These data layers are expected to be updated and available near the start of the project. The City is planning to update the model with the latest pipes in the GIS. The City's GIS currently has a level of granularity that may result in many pipe segments that are not necessary for the model and could increase simulation times. If the number of pipes causes undesirable performance, the model will be skeletonized to combine pipe segments of the same diameter and material. The City has been surveying water system infrastructure such as pumps, reservoirs, zone boundary valves and PRV stations. This data will be provided for Carollo to update the facilities information. Carollo will also review the pump station, reservoir, and PRV information in the model currently and compare with the City's information to check that these facilities are represented correctly in the model. Carollo will visit selected pump station and reservoir facilities that have been constructed or significantly updated since the last model development study. The model will be configured so that hydrants in the distribution system are uniquely identified and associated with nodes in the model. This will allow fire flows in the model to be simulated for each hydrant. The model will be updated to include infrastructure that is currently being designed but not yet constructed. This proposed infrastructure will be phased into each scenario, including buildout. 1.3 Demand Projections Demand projections will be developed based on recent customer billing information and the land use plan. Customer billing records will be spatially located to the property locations where the water is used for existing customers. Demands will be set to correspond to the water use in the past two years, including unaccounted for water. Unit demands will be established for land use classifications based on the customer billing information associated with each land use classification. Demand projections for undeveloped lands will be set based on the land use plan and unit demand associated with each land use type, which will include current conservation measures. If future demands are expected to decrease due to more stringent conservation measures, then future demands will consider the effects of conservation. Per capita demand values will be established based on 2010 census data. Growth projections will be derived from the land use information in the General Plan Update. Carollo will take information to be provided by the City, including development master planning projects, population projections, and other data. Some studies will h:\bd_phx\prescott\water model update\prescott water model update project 06192012.docx 2