WSP00978

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1982
• Title: Optimizing Salinity Control Strategies for the Upper Colorado River Basin
• Water Supply Pro - Doc Type: Report/Study

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Deealination--
For regional salinityqo~trol evaluat~~ns, desalting costs are expressed
in dolls1:'s per unit volume of salt extracteclin the brine c1ischarge rather ..
than the conventional in~ex of costs per unit volume of reclaimadprolluct
water. In this manner the respective feasibility of c1esslination and other
alternatives f.or salinity. management: cen be systlOliiat.ically compared during the
processes of c1eveloping etratagiesfor actual implementation of salinity
controls. A desalting system as used herein consists of facilities fo1:'
supp;tying raw water (wster to be desalted). to the plant, the c1esalting plant
itselfancl facilitias to conveyancl c1isposeof the brine. Transportation of
product water beyond the confines of this system is not considered.

While recognizing the site-specific nature of c1esalting technology as
applied to regional water quality management, some geneTalization of the cost-
effectiveness relationship can be made. A detailed evaluation of input param-
eters to a desalting cost analysis was p1:'esentedby Walker (1978). All
systems are most sensitive to the cepacity of the desalting plant. When the
'costs aTe expressecl in terms of salt removal, the unit costs stabilize to
n3a1:'lY constant vslues when the capacities sre gTeaterthan about 10-15,000
m Iday'. Since c1esalting would be most competitive with the salinity control
alternatives when t~eunit costs3are minimal, only systems with capacities
greater than 0.17 m is (15,000 m /day) should be considered. '):he result of
this c6nsiclerationis that the desalting cost-effectiveness functions are
approximately linear.

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For the purpose of formulating a desalting cost-effectiveness function
which can be evaluated slongwith other salinitYc6ntrol messures, . the model
by Walker (1978) was updatecl to January, 1980 conclitione. Then; the. model'was
used to generate cost-effectiveness curves for feecl"Water saline types ranging
froll\ 1,000 .to 9,000 mg/l. These.functions shown in :Figure~O were then con-
siderecl into the following mathematical form:

C = 0.5+ M'S
d 1

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in which,

Cd= annual cost in $ million of removing Sl,thousands of megegrams per
ye'ar; and

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wheT.e,

TDSi = feeclwater salinity. mg/l.

The disposal of brine from desalination plants and/or brine pumping
programs such as the Paradox Valley Project, is s severe problem in many of
the salinity control programs. The alternatives which are most commonly
discussecl are evaporation ponds ancl c1eep weil injection. Ponds are limited by
area and volume availability whereas injection techniques depend on the

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