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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in this category, so the simplifying assumption is of no major
consequence to the outcome of the study.

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DETERMINATION O~ IMPACTS OF YDP PRODUCTION

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Thirty two of the proposed plans would provide a source of water
to substitute for drainage water. In cases where a plan would
provide substitute water, an equal amount of drainage water would
be bypassed, reducing the amount of drainage water that must be
treated by the YDP. In some cases, the plans provide sufficient
substitute water 90 that YDP production would not be required.
In other cases, the plans would not provide sufficient water to
completely eliminate production from the YOP but would supply
enough to significantly reduce the amount of drainage water that
must be treated by the YDP. Thus, an analysis of each plan's
impact upon YDP production was required before all plans could be
fully evaluated.

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The analysis was completed using computer model YDPSHORT.FOR that
simulated the production from the YDP and the operation of the
Colorado River between Imperial Dam and the Northerly
Internationa~ Boundary (NIB). The computer mode~ YDPSHORT.FOR
has the capability of simulating YDP production using various
configurations of inflows, outflows, YDP capacity, blend
proportions, and salinity differentials between Imperial Dam and
NIB. A number of simplifying assumptions are incorporated into
the model to simplify the analysis, so results of the model
simulation do not precisely duplicate actual projected production
required of the YDP, but model results are considered
sufficiently accurate for the purpose of comparing plans. A
summary of options and a documentation of the computer model
YDPSHORT.FOR are in Appendix B attached to this report.

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For example, the base case for comparison purposes was assumed to
be the projected production from the YDP based on treating a
return flow of 110,000 acre-feet with a salinity of 3,200 mg/L.
Salinity of the Colorado River at Imperial Dam was assumed to be
879 mg/L. Present detailed operational projections indicate that
a 72.4 mil~ion gal~ons per day (Mgal/d) plant could treat the
inflow with about 28,000 acre-feet of reject flow wasted to the
Santa Clara Slough. The YDPSHORT.~OR simulation, however,
indicated that a 66.7 Mgal/d plant would meet the Minute, deliver
72,000 acre-feet to the Colorado River, and waste about 38,000
acre-feet of bypassed water. Thus, for comparison purposes in
this study the base case was assumed to be a 66.7 Mgal/d plant
producing about 72,000 acre-feet, and wasting about 38,000 acre-
feet of reject and bypassed water. The reject stream replacement
requirement would be 38,000 acre-feet of water per year.

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