C153773 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I the expense of traffic control. The preferred alignment is shown on Drawing IV-A. Information from references 16, 19, 20, 21 and a field reconnaissance check was made to select the general route. The alignment is shown approximately 7,000 lineal feet, of which 5,000 feet will be at the toe of the slope in colluvium, and 2,000 feet will be through operations at Cooley, likely excavated in rock. Recommended Alternative Plan The delivery of water to the treatment plant through the gravity intake is adequate to meet current demand. However, the existing system does not have the additional capacity to supply the operating reservoir for subsequent pumping to fill Cooley Reservoir. Before Cooley Reservoir is brought on-line, the upper reach of the intake pipeline must be rehabilitated to provide adequate flow rate capacity for diversions to storage. Although this upper reach of pipeline and stilling basins are in poor condition, they can continue to serve development and minor additional growth in order to phase capital improvements in the near term. The diversion dam on Bear Creek should be improved for reliability and reduced maintenance, however, there is no firm deadline for this work. It would be convenient to complete work on the dam at the same time work is underway on the intake pipeline since water will be shut off to the intake and the contractor will be accessing the site at the dam, and therefore, would result in some cost savings to complete both projects at the same time. However, it may be preferable to postpone reconstruction of the dam until the Cooley Reservoir is completed, and demand can be met with water in storage while the intake is shut down. An economic comparison between options B-1 and B-2 is presented in Table Ill-C. The approach used is that of the comparative annual cost. To simplify the comparative analysis, we have assumed that all the capital improvements would be required in 1997. (Note that this would tend to favor Option 2 because there is less credit given to existing facilities but correction would not change the conclusions.) The comparative costs will vary somewhat, dependant on total EQR served (total water used) which primarily affects operating and maintenance costs. Therefore the comparison is made for a 500 EQR development level and a 1000 EQR level - both using estimated 1997 cost levels The recommended alternative is Option B-1. It involves significantly less cost at all times - and, in addition, offers more investment phasing flexibility. 70-0aO.035:MSTR.PLN 111-14