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<br />:":\ <br /> <br />to <br /> <br />~ <br />C": <br /> <br />c <br />C <br /> <br />dissolved solids content at Lees Ferry presently averages 544 ppm and, <br />by the year 2000, will average 735 ppm, for an increase of about 35%. <br />(Note: The Board's Salinity Report projected Lee Ferry salinity in <br />year 2000 at 800 ppm.) Blowdown water is estimated to vary between <br />3,000 ppm and 5,100 ppm based on historic water quality profiles of <br />TDS in the vicinity of the intake. Future concentrations would range <br />from 4,050 ppm to 6,900 ppm at 6 cycles of concentration. <br /> <br />The report estimates that under conditions of full development with <br />an estimated 35% increase in TDS at Lees Ferry to 734 ppm, the maximum <br />weighted annual increase due to the Navajo blowdown would amount to 3 <br />ppm increase at Lees Ferry. This amounts to an increase of .43%. Based <br />on this small increase in salinity which the blowdown would cause, the <br />report concludes that economic losses to other users would not be signi- <br />ficant. The report also concludes that no significant ecological con- <br />sequences will occur as a result of the return of blowdovm to the lake. <br /> <br />In addition to the scheme for disposing of blowdown water by dis- <br />charging it into Lake Powell, which the report recommends, seven other <br />possible schemes for onsite disposal of blowdovm water were also pre- <br />sented, without any cost data. These schemes are very briefly described <br />in the report and are as follows: <br /> <br />1. Onsite Evaporation Pond (Option IB). Blowdown <br />towers would be piped by gravity to evaporation ponds. <br />would be approximately 655 acres. <br /> <br />2. Pretreatment and Evaporation Pond (Option 2A). The cooling <br />tower makeup would be lime - soda - ash softened to prevent scale <br />formation at 13 cycles of concentration. The blowdown water would be <br />sent to evaporation ponds having an area of 189 acres. <br /> <br />from the cooling <br />The pond area <br /> <br />3. Reverse Osmosis and Flash Evaporation (Options iA and iB). Thes <br />were considered as systems for treating the blowdown water at 6 cycles of <br />concentration. Equipment and operating costs would be extremely high <br />because of the high flow rates. <br /> <br />4. Electrodialvsis (Option iC). Cooling tower operation would be <br />less than 6 cycles of concentration and the blowdown water would be sent <br />to an electrodialysis treatment plant where it could be processed so that <br />75 to 80% would be available for reuse. The resulting brine would be <br />sent to an evaporation pond. <br /> <br />5. Pretreatment and Electrodialvsis (Option 4A), .Cooling tower <br />operation would be less than 13 cycles of concentration with blowdown <br />water treatment to concentrate the wastes and partial lime - soda - ash <br />softening of the makeup would be included. Electrodialysis equipment <br />would be used for blowdown treatment. Concentrated wastes would be <br />pumped into evaporation ponds for disposal. <br /> <br />6. Pretreatment and Reverse Osmosis Caption 4B). Treatment <br />cooling tower blowdown water would be by means of reverse osmosis <br />ment with pretreatment of plant makeup water as discussed above. <br /> <br />of the <br />equip- <br />Cooling <br /> <br />2. <br />