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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Plan A-2.
Cost $25.9

Ooerate the YDP with Off-Peak. Firm Power.
million, TVS 1043 points, Category I

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This plan is similar to Plan A-I. However, except for pre-
treatment, the YDP would not operate during hours of peak power
consumption. This would save 70 to 80 percent of power
requirements during the supply system peak hours, reducing the
overall power requirement 15 to 18 percent and reducing the
effective YDP capacity by about 25 percent. Desalting equipment
(the high-power consumer) would be shut down during peak hours.

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Annual O&M costs, including the cost of the additional reject
stream replacement water that would be required, would be about
$25.9 million per year. Reject stream replacement requirements
for this plan would be about 56,600 acre-feet per year.

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Advantages:
'This plan saves 70 to 80 percent of energy requirement during
the peak hours.
'Power costs are reduced - by reducing the plant productivity and
utilizing offpeak rates.

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Disadvantages:
'The YDP output is reduced (75 percent of rated productivity or
67.S-percent plant factor) and wil~ not a~ways meet the Minute.
'DeBa~ting equipment wou~d be cycled on and off with unknown
effects on the membrane e~ement life and performance.
'The life of other mechanical and electrical equipment is reduced
and their maintenance costs are increased.
.The time required to shut down and start up the YDP may be
longer than anticipated (30 minutes for control block - staging
control b~ock unknown).
'The pretreatment p~ant would need to be modified because only
2/3 of the water entering it can be bypassed.
'The plan requires increasing the brine stream replacement, or
reducing Arizona's return flow credit.

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Plan A-3. Ocerate the YDP with Non-~irm Power.
Cost $24.6 million, TVS 1058 points, Category I.

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This plan is simi~ar to Plan A-2. However, in this case, the
power supp~y could be interrupted by the power company with
little notice depending upon other power demands. The p~an
assumes loss of power to the desalting equipment only, and
assumes pretreatment plant and remainder of YDP would have firm
power. If pretreatment were stopped, it could take hours or even
days to bring it back on-line. Emergency power supplies would

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