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If,OJ-t 5]_ ___ 1----'--- ,-- il 'I il ~: :1 " , II I I' I I I I I I -. I "\:. !I :1 I' I II :1 " ~---- ---. -25- sand and gravel. We wish to point out again that to be conser- vative in the seepage analysis the geologic conditions were as- sumed to be m0re severe than they actually area. For the analysis the blanl,eting effect of the Aeolian deposits on the surface was ignored and the deep inner channel was assumed to be located directly under the present river flood plain. Also the question of constructing a cutoff was considered but the maximum seepage rate was determined under the assumption that no reservoir blan- keting or cutoff would be made at all. In the analysis, it was pointed out, however, that a~y cutoff measures employed would significantly reduce the seepage losses further. The problem of obtaining impervious materials for the core of a dam were resolved to the point that we now know that some ten million cubic yards of impervious soil is available within an average haul distance of seven miles. This is an increase of approximately six miles OVel' the avel'agc haul distance required at the Narrows site and represents an overhaul at the lower Weld County site to the extent of the volume of the impervious core. This represents a definite dollar cost in favor of the Narrows site, but cannot be accurately determined l1lltil the impervious , " section of the dams have been at least tentatively deSigned. An " " example of comparative costs as related to overhaul was shown above. It is our belief that a sound design can be made utilizing I a thin impervious core section and the overhaul cost be thus '<<.' .~ ~' -, reduced. In evaluating the effect of various types of cutoff for the , lower Weld County dam it was our opinion that there would be no " ,I ;1 'I l _-.~:"":';' ~-~--:::_-._ unusual construction difficulty or excessive cost involved in -J .' L- or" ...., ~...~t, ..". ~ ' ..". .