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Cost of Desalted Water and YDP Cost Reduction Program . drainage costs about $773 per acre-foot, These costs are within the range provided in the MWD report. However, the cost ofYDP product water is greater than the range recommended for general cost estimating for several unique reasons: " . To reduce life-cycle costs, the YDP was designed for a 50-year life expectancy. This design required more durable, higher cost equipment and materials such as aluminum bronze piping, gravity back wash filters, and concrete vessels, . The feed water, WMIDD inigation drainage, is conveyed to the YDP in an SO-mile-Iong open drain exposed to windbom sand and runoff, which creates a high suspended solids loading. This debris is difficult to remove and requires extensive pretreatment facilities. . The drain is expoeed to intensive direct sunlight, which encourages the growth of aquatic weeds and algae that become part of the feed water. As a result, additional pretreatment facilities are needed to remove this biomass. Introducing the White Amur (grass carp) into the MODIMODE could control the biomass (this fish effectively contTols aquatic vegetation), However, the Arizona Department of Game and Fish has restricted stocking of the grass carp in the Yuma area within 1 mile of the lower Colorado River, This option will be explored in the future if the department changes its position on the I-mile restriction, . For esthetic reasons, a significant portion of the YDP's piping and equipment were located underground, at increased cost. . Design work was completed on a "piece- meal" basis over a 15-year period to reduce the impact on the annual budget. As a result, overhead composed a larger than usual portion of the total design cost. . Construction work was completed over a 10-year period (1) to reduce the impact on the annual budget, (2) to ensure plant completion coincided with actual need, (3) to allow construction to follow the design work, and (4) to allow the completion of higher priority Reclamation work such as the CentTaI Arizona and the Central Utah Projects. As a result, overhead costs increased, coordination between construction contracts was made more difficult and expensive, and multiple contracts were required, eliminating the discounts associated with larger procurements. Annual YDP Operations Costs As shown in table 4, full-capacity operation of the YDP under long-term operating conditions will ~ost about $32 million per year, Table 4 also shows estimated fiscal year 1993 operation and maintenance costs for a range of operating scenarios, In addition, transitional years will occur between full operation and standby (and vice versa). Projected costs for any given year depend on what occurred the previous year as well as what is planned for the following year, This creates a wide range of possible operating costs; figure 2 illustrates one possibility, The first year after full operation in a transition to standby would include overhead and nonroutIDe main- tenance costs. Nonroutine maintenance includes work scheduled to be performed during standby; otherwise, plant shutdown would be required.. After a period of standby, and assuming that full operation will resume at the beginning of the next calendar year, startup costs will be incurred in the calendar year before the year operation begins, Startup costs will include increases in chemical, power, and personnel costs. After a period of standby, about 3 months of pretreatment and desalting equipment startup will be required before full operation can occur at the beginning of the year, Annual maintenance contracts and ailminiRtrative 21