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Ciry of Aurora Agenda Item 9f January 23-24, 2007 (REVISED January 29, 2007) Page 3 of 7 must obtain a water court approved plan for augmentation. The City's legal council does not foresee any legal impediments to obtaining the required water court approvals of the augmentation plan to operate the PW P. Water Storage - Storage within the raw water supply system is extremely important to meet annual operational needs as well as demands during extended dry periods. Aurora Water utilizes its storage facilities annually to meet fall and winter water demands. The need to use reservoirs for annual operation will continue into the future and will become even more critical with additional City growth. During dry years when direct diversions do not satisfy annual water demands, water demands are met by water delivered from long-term reservoir storage. A review of supplies versus demands shows that this hydrologic situation occurs about 15-percent of the tirne, or on average about once every seven years. Proiect Description � Development of the Prairie Waters Project Aurora Water initially considered 37 raw water supply project elements. These elements were screened down to 24 potential project components, and subsequently evaluated using a decision analysis, which included permitting, institutional, public, schedule, cost, yield, flexibility, and sustainability considerations. The components were assigned a weight and each project component was scored and ranked. Because none of the 24 project components considered could individually me�t future water demands, it was necessary to combine various project components into "portfolios of projects" to provide a long—term water supply solution. Each of the �even potential project portfolios included phased implementation of selected projects to meet th� City's increasing wa�er demands. Projec# phasing was based on meeting projected dry year water demands at least five years before the demand occurs. The evaluation concluded that the first project that should be constructed to meet near term water demand is the Prairie Waters Project. The PWP will put the City ahead of the demand curve for several years and provide "drought hardening" of the existing system. Alternatives Analysis for the Conveyance System In 2004, Aurora Water and its team of professionals began identifying and evaluating alternative alignments for the Conveyance System. Three alternative preliminary pipeline alignments were carried forward from the initial screening process: • Alternative 1 - E-470 Alignment • Alternative 2- DIA East Alignment • Alternative 3- Monaghan Road Alignment All three alignments start at the North Campus located near Brighton. Each route offered distinct advantages pertaining to pipeline length; environmental factors; number of highway, railroad, irrigation ditch, stream, and utility crossings; number of landowners; and the extent of developed land traversed by the pipeline. Based on evaluation of the three alternatives, Alternative 1, the E- 470 alignment, was carried forward as the preferred pipeline alignment. This alternative was selected primarily to streamline right-of-way acquisition and because it presented the fewest environmental impacts. Pumping stations are needed to lift the water approximately 1000 feet from the North Campus to the purification facilities at the South Campus (also known as the Aurora Reservoir Water Purification Facility or ARWPF). Locations for the pumping stations were identified at interim points along the conveyance system so that the same pump motor horsepower could be used at each of the pumping stations. Alternative sites were then evaluated based on land and pawer availability. The Conveyance System is comprised of the following four bid packages: