WSP07975

• File Number: 8278.100
• Description: Title I - Yuma Desalting Plant
• Basin: Colorado Mainstem
• Date: 10/1/1987
• Author: USDOI/BOR
• Title: Yuma Desalting Plant Operations Study - Draft Special Report
• Water Supply Pro - Doc Type: Publication

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DBSCRZPTZOH OF PROPOSBD PLAHS

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The following is a description of each of the proposed plans.
The plans have been grouped as previously described. The
discussions include the results of model studies run with the
program YDPSHORT.FOR to determine the impacts of various plans
upon YDP p~oduction ~equirements. Because of simplifying
assumptions built into YDPSHORT.FOR, results should be considered
valid for comparison purposes only and not be considered for
updated YDP capacity or reject stream replacement requirements of
the presently planned YDP.

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GROUP A - OPERATIONAL AND STRUCTURAL CHANGES TO YDP
This set of ten plans examines the effect of structural and
operational changes to the YDP itself.

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Plan A-I ODerate the yOP as Presentlv Planned tBase Case).
Cost $27.5 million, TVS 1173 points, Category I

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This is the base case to which the other plans are compared. The
actual plan assumes 72.4 Mgal/d capacity; YDP would operate 330
days per year with 35 days allocated for maintenance and outages
(a 90-percent plant--factor). Capital costs are about $19 million
per year and projected annual operating costs, inclUding cost for
reject stream replacement, are estimated to be a~ much as $27.5
million per year during years of full YDP production. Standby
costs are estimated to be about $5 million during years when YDP
production is not required. Capital costs are sunk costs and are
not included in any cost estimates. About 110,000 acre-feet of
3,200 mg/L drainage wate~ from the Wellton-Mohawk is collected
and conveyed to the YDP each year. Under full production, the
YDP would produce 78,000 acre-feet per year of usable water
(80,000 acre-feet per year with blend). About 28,000 acre-feet
reject would be discharged into the Santa Clara Slough each year.
The resulting cost of the product water, including blend, is
about S600 per acre-foot. About 75,000 acre-feet of other
drainage from other wate~ districts between Imperial Dam and the
NIB is returned to the Colorado R~ver as return flow but not
treated by the YDP. The average salinity of these flows is
1,500 mg/L.

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The least costly plan for replacing the reject stream requires
lining the All-American Canal (AAC) in-place with a plastic
membrane and concrete lining to conserve water now being lost as
seepage. A portion of the conserved water would be used to meet
reject stream needs. The remainder of the conserved water would
meet municipal and industrial needs in Southern California. A
total of about 70,000 acre-feet to 75,000 acre-feet of water can
be conserved annually. The California water users have indicated
a willingness to allow Federal use of conserved water for reject

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