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<br />w <br />~ <br />cn <br />co <br /> <br />2. Bas,e Case <br /> <br />Since initiation of studies under the CRWQIP in 1974, the feasibility of, <br />treating water from each point and diffuse saline water source in the <br />8asin h~s been studied individually to varying degrees of detail. In <br />general, the methods considered desalting of the flows or disposing of <br />the flows in lined evaporation ponds. The cost-effectiveness of these <br />proposa~s is of growing concern and other measures need to be evaluated. <br />Taken in combination, a set of structural control project proposals is <br />considered as a "base case" to provide a frame of reference in which to <br />evaluate the relative cost-effectiveness of the energy-related alterna- <br />tives developed in this report. Specifically, the base case consists of <br />treatin~ the saline discharge at each site by desalting, returning the <br />desalte9 water to the river system, and disposing of,the desalting plant <br />brine effluent in a lined evaporation pond. If desalting and lined pond <br />measure$ were implemented for all applicable sources in the Basin, such <br />a plan would reduce salinity at Imperial Dam by 160 mg/L and would <br />remove 110,000 acre-feet of water annually from the river system to <br />evaporation ponds, <br /> <br />Appraisal-level estimates of cost-effectiveness for desalting plants are <br />available only from the LaVerkin Springs Unit and the Glenwood-Dotsero <br />Springs'Unit at the present time, <br /> <br />The LaVerkin Springs cost-effectiveness was $1,474,000 (January 1981) <br />per mg/~. The project uses a membrane desalting process to treat <br />10,000-~g/L TDS water, A brine disposal area would be located nearby <br />using lined evaporation ponds. The Glenwood-Dotsero Springs cost- <br />effectiveness was $1,400,000 per mg/L (1981), reflecting similar <br />advanced desalting technology treating 14,000- to 18,000-mg/L TDS water. <br />Based on studies made for various other projects having desalting <br />plants,a maximum value of $2,000,000 per mg/L for treating 3,000 mg/L <br />TDS water was used to represent upper cost-effectiveness limit of the <br />base case, Based on this cost-effectiveness range, total annual Federal <br />program ~osts would be about $335,000,000 with a total investment of <br />$4.8 billion if all (desalting and ponds) structural measures were <br />implemented. The base case assumes that the most cost-effective mea- <br />sures s~ch as onfarm irrigation improvements and canal and lateral <br />lining Will generally have a higher priority of implementation than <br />structural measures and wou1 d already be imp 1 emented. <br /> <br />3. A 1 tern at i ves That Show Promi se <br /> <br />a, Local Use Options. - The local use option involves the collection <br />and transport of saline wa~er to a nearby powerplant or other indus- <br />tria': water use sites for use in cooling and disposal. Figure 11 <br />presepts a conceptual schematic of the local use option. In order to <br />show reasonable cost-effectiveness, it was found that the powerplant <br />would have to be located within about 100 miles of the saline water <br />source. <br /> <br />V-3 <br /> <br />.~. , <br /> <br />j <br />;, :~ <br />,iL'~ <br />