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<br />~ <br /> <br />" <br /> <br />. <br /> <br />. <br /> <br />For those sites selected, the seepage loss conditions before and after <br />the bentonite treatment will be obtained. For the smaller diteh sites, this <br />involves, in most instances. installation of a water measuring device at the <br />upstream and downstream ends of the treated section. For the large di tches, <br />installation of water measuring devices may not be economically feasible, but <br />observations of nearby seepage areas will be utilized. For ponds, the rate of <br />drop of pond level would be measured. As yet no actual installations have been <br />made nor measurements begun, but measuring deviees are scheduled for <br />installation in one or two sites in the Buena Vista area during the first week in <br />May. <br /> <br />The evaluation work, such as mentioned above, will include experimental <br />work with varying bentonite application rates, (i. e. l!Z-lb! sq ft, 1. 0 lb! sq ft, etc.) <br />but until these results are obtained, the tentative application rates reeommended <br />for Colorado bentonites are listed below: <br />1. For sandy soils- - Z. 0 lbs! sq ft of treated area or layer I! 3-inch thiek. <br />Z. For gravel and rock-- 3. 0 lbs! sq ft of treated area or layer l!Z-inch <br />thick. <br /> <br />The above rates are based on a pit-run bentonite that has been air- <br />slaked down to 90 per cent smaller than I-inch size and with no lumps larger <br />than Z-inches in diameter. A I-inch thick layer of pit-run granular bentonite <br />is equal to about 7.0 lbs/ sq ft of treated area. <br /> <br />The information on the thickness of bentonite layer for eaeh application <br />rate has been included for the farm pond installations, where the bentonite <br />preferrably is spread dry, thoroughly mixed into the top 3-inches of sub-grade <br />soil, and then firmly packed with a sheeps-foot roller or other compaction <br />method. Where the bentonite is floated into place with flowing water, such as <br />in most of the recent ditch sealing applications, the bentonite spreading is not <br />a problem, but the same minimum application rates are recommended until <br />apditional field trial experience indicates that changes should be made. <br /> <br />-4- <br /> <br />1007 <br />