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<br />. . <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />CU021n <br /> <br />only be done, of course, with the full cooperation of the farm operators <br /> <br /> <br />in adopting and following improved management techniques. The cost of <br /> <br /> <br />increasing efficiencies on up to an average of 75 percent requires more <br /> <br /> <br />capital investment and operating costs, This could amount to a total <br /> <br /> <br />annual cost for the study reach of $3.75 to $4.5 million. <br /> <br />Canal Efficiency Improvement Costs <br /> <br />Estimated costs for lining selected canals and ditches are given in <br /> <br /> <br />Table 9 for those ditches or canals having an estimated seepage loss in <br /> <br /> <br />excess of 25 percent which were considered for lining. For each of the <br /> <br /> <br />10 canals or ditches, wetted perimeter measurements were made at selected <br /> <br /> <br />locations along the reach of each system. These data were used to establish <br /> <br /> <br />an existing wetted area. Cross-sectional width and depth and slope of <br /> <br /> <br />the various reaches were also established, <br /> <br />In the cost estimate, five different lining processes were considered: <br /> <br /> <br />(1) bentonite, (2) 12 inches of compacted earth, (3) ,010 inch PVC with <br /> <br /> <br />12 inches of compacted earth cover, (4) 1/4 inch of catalytic blown asphalt <br /> <br />with 12 inches of compacted earth cover, and (5) 3-1/2 inch thick unrein- <br /> <br /> <br />forced concrete. Costs per square foot for each of these treatments <br /> <br /> <br />(including material and installation costs) were established from exper- <br /> <br /> <br />ience, interviews with suppliers, cost data supplied by the U. S. Bureau of <br /> <br /> <br />Reclamation, Denver Federal Center, and construction cost trends~ The unit <br /> <br /> <br />costs for each of the five processes are enumerated in the table. <br /> <br /> <br />Thebentonite lining is the least expensive of the five, but it would <br /> <br /> <br />be expected to require more annual maintenance and supplemental replenish- <br /> <br /> <br />ment, An application rate of 5 pounds/square foot applied by the wash-in <br /> <br /> <br />method was considered. This method application requires very little pre- <br /> <br /> <br />liminary work and a minimum of expense and time to install. With the <br /> <br /> <br />wash-in method,only a near-surface seal would be achieved and should not <br /> <br /> <br />be used where velocities are excessive or where considerable bed material <br /> <br /> <br />transport is anticipated, It is recommended that only three of the ten <br /> <br /> <br />ditches be considered for this treatment process--Springdale, Bravo, and <br /> <br />Peterson, The compacted earth, the PVC, and the catalytic blown asphalt <br /> <br />-53- <br />