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CONCLUSIONS AND RECOMMENDATIONS 1. Where is clay sealing applicable? The methods Wlder development by this project are aimed primarily at (a) supply canals of irrigation companies and districts, and (b) any canals (dis- trict' company or individual) in rocky to gravelly materials of the mountainous sections of Colorado. 2. What is an acceptable clay? This is still being determined, but, in general, we are looking for clays which when placed loose as a layer about i/Z-inch thick will hold water (3-foot depth or more) with the loss restricted to i-inch or less drop in water level in 24 hours. In addition to this require- merit, a clay suitable for wash-in applications in canals should mix easily in flowing water (mixa- bility index of 50 percent or more). 3. What are the recommended methods? Without going into the actual procedures, the initial evaluations indicate that the best methods are: a. For canals in rocky and gravelly material The wash-in and the multiple-dam methods are recommended provided (a) the right clay is used, and (b) follow-up treatments are carried out. The right clay means one that will stay in place under the expected canal conditions. The follow-up treatment (usually 10 percent of initial treatment amount) consists of washing clay in with the first water in the canal each spring for at least two years after the initial treatment. The buried clay membrane method is also recommended but may be quite expensive in rocky areas. b. For canals in sandy to silty soils The buried membrane method, if properly used, is recommended for these soils. The wash-in methods are not yet recommended -- the development work on the latter methods is not complete. c. For ponds in leaky soils -- The buried membrane method is the recommended one - - al- though development work on wash-in modifications is still under way. The beaching or water~line erosion is a major problem which requires special treatment for ponds in windy unprotected locations. Piling rip- rap or extra clay or bentonite in the water-line zone has been used to control this problem of erosion. 4. Where is additional development work needed? a. Additional deposits of clay are needed especially in the northeastern and southeastern sec- tions of Colorado. b. Additional evaluation and development of laboratory procedures used for testing the clays is needed to establish reliable tests. c. Additional development of known clay deposits is needed. Contractor help, both in develop- ment and in selling of clay-sealing work, is needed. d. Additional field trials are needed __ especially in canals located in sandy to silty soils. Contractor help (as mentioned in c above) and in- stallations by irrigation companies and districts are needed. 1051 7