AZ vs. CA:18 California Exhibits, Vol. XVIII; Nos. 3500A-3550

page 28

[28] age structures of adequate capacity to assure the safety of the canal during storms of cloudburst proportions which are a characteristic of this general region. The canal grade, in a majority of cases, would be below the grade of the drainage washes it crosses, in some cases 60 feet or more. This would require that a dike be constructed at each end of the siphon and of such strength that it would not wash out in the severest storms. Should one of these dikes fail, the canal would be filled with gravel and sand for hundreds of feet. Cleaning the canal would be a lengthy process owing to the depth of the canal cut and the large amount of debris likely to be involved. During these periods of clearing and repair to the canal, the Palo Verde District would be without irrigation water and as a result would probably suffer severe crop damage. Thirty-five siphons, varying in length from 100 to 1,000 feet, with protective works at each, would be required. Construction for initial delivery of 1,000 second-feet would entail excavation of about 23,000,000 cubic yards of earth and 410,000 cubic yards of rock, as well as borrow of 850,000 cubic yards of earth required for canal bank construction where fill exceeds cut. For 13.3 miles the average vertical cut would exceed 50 feet and in some instances 75 feet. This excavation would be through water-worn Colorado River gravel, angular detritis from nearby hills, and varying amounts of sand and silt. There is some evidence of cementation in the formations along the canal route, but it is not believed that blasting would be required to break this up.