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I I I I I I I I I I I I I I I I I I I 4-2 existing pipeline by lining or other methods, because of its age and state of deterioration. The capacity of the existing pipeline has already been reached by the demands of the Cortez water service area, so new transmission facilities are required. New Raw Water Supply pipeline In planning for new raw water supply facilities, several factors have to be studied before conclusions are drawn about the nature of the new pipeline. These factors include pipeline alignment, materi- als of construction, fittings, sizing, and ancillary structures such as hydroelectric stations, flow metering, and diversions. The discussion of pipeline alignment is presented separately in Chapter 5. pipe Size Analysis. In order to adequately plan transmission facilities for the full economic life of the facility, a 50-year pipe size analysis will be performed. This will ensure optimum life-cycle costing. Figure 4-1 shows a range of pipe flow characteristics for the projected maximum day supply of 27.8 million gallons per day in 2035, with 390 feet of elevation available along the alignment. The raw water supply pipeline must be sized for the maximum day demand. The maximum day flow estimated for the Cortez area in 50 years is approximately 27 million gallons per day. The head-loss flow relationships for concrete lined piping is illustrated on Figure 4-1 for pipe sizes ranging from 20 to 30 inches diameter. This series of characteristics indicates that the selected pipe size should be 30 inches diameter. Use of a 24-inch line will not pass the 50-year projected flow and after 2025, peak velocities will exceed 10-feet per second. The 30-inch diameter pipe will pass the expected 50-year flow and provide capacity beyond this time. pipe Material Selection. pipe material considered for use on the proposed raw water supply pipeline includes modified prestressed concrete cylinder pipe (MPCCP) and ductile iron (DIP). Unit costs for these materials are summarized in Table 4-1. Based on prelimin- ary cost information, MPCCP is the less expensive material. For the purposes of budgeting, ductile iron has been used together with restrained joint DIP at wash crossings and bends. These recommendations have been included in the cost estimates presented later. These difference in material cost between MPCCP and ductile iron will not be necessarily reflected in total project bids. Ductile iron will be less expensive to install than MPCCP. Appurtenances. Several fixtures and appurtenances will be provided along the pipeline. BROWN AND CALDWELL C CONSULTING ENGINEERS