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E.cq <br /> <br />ES.3 Alternatives Development and Evaluation <br />Eight preliminary alternatives were developed for hydraulic analysis. The eight alternatives <br />encompass a full range of possible system configurations, so different levels of service to the <br />three geographical areas and customer priodty levels could be investigated. In addition, both <br />centralized and decentralized storage and pumping options were included to investigate the <br />cost-effectiveness of different system configurations. The alternatives ranged from small <br />systems (Priority 1 and 2 customers in Redwood Shores only) to City-wide systems (Priority 1, <br />2, and 3 customers in all three geographical areas) providing a range of new water supply from <br />just over 1,100 AF/yr up to approximately 3,172 AF/yr. <br /> <br />Preliminary estimates of capital costs and cost effectiveness (cost per acre-foot of water <br />delivered) were developed for the eight preliminary alternatives based on pipeline sizes and <br />lengths, storage and pumping capacity, treatment costs, and standby connections. The <br />conclusions drawn from the preliminary altematives analysis are as follows: <br /> <br /> · The cost effectiveness of City-wide alternatives that serve only Priority 1 and 2 <br /> customers tends to be much lower than for alternatives that include Pdority 3 customers. <br /> When the Priority 3 customers are added to City-wide distribution systems, the cost- <br /> effectiveness increases by about 35%. This is because Priodty 3 customers make up a <br /> large percentage of total potential recycled water demand outside the Redwood Shores, <br /> and the transmission pipeline system becomes more cost-efficient when the Priority 3 <br /> customer demands are included. <br /> <br /> · Preliminary alternatives with centralized storage and pumping at SBSA are more cost <br /> effective than the altematives with decentralized storage and pumping. The cost <br /> required for decentralized pump stations is greater than the cost savings realized by <br /> reduced pipeline sizes in the transmission system. <br /> <br /> · In an attempt to improve cost-effectiveness of a City-wide project while maintaining a <br /> substantial recycled water supPly, fine-tuning was performed by eliminating distribution <br /> pipelines to customers that appeared to be relatively expensive on a cost per AF/yr <br /> delivered basis, A slight improvement in cost effectiveness was realized in this fine- <br /> tuning. <br /> <br /> Based on the results of the preliminary alternatives evaluation, final alternatives were developed <br /> to meet the range of the City's projected water supply needs, while providing the best value and <br /> preserving flexibility for future system growth and expansion. All of the final alternatives <br /> included some level of service to Priority 3 customers. The four Final Alternatives A through D <br /> are summarized in Figures ES-1 through ES-4. To preserve flexibility for future expansion of <br /> the recycled water system, the transmission pipelines are sized under each final alternative to <br /> serve all of the Priority 1, 2, and 3 customers in each of the thrte geographical areas (as in <br /> Alternative B). <br /> <br /> ES.4 Recommended Project <br /> Based on an evaluation of cost-effectiveness, water supply, and future fiexlbility considerations, <br /> Project Alternative D is recommended to the City for use in project planning and <br /> <br /> Water Recycling Feasibility Study for Redwood City vi <br /> <br /> <br />