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<br />OOOC(: <br /> <br />-14- <br /> <br />arc known to sustaill considerable lcaka[;e. <br /> <br />,- <br /> <br />Materials explorations and testing for the Narrows site have <br /> <br />,-' <br /> <br />been very extensive, one of the largest prO[;ralllS eVE:r carried Ollt <br /> <br />by the U. S. Bureau of RcclamatiolL Construction Inaterials total- <br /> <br />ing approximately 12 1/2 million cubic yorels were explored and <br /> <br />testcd in areas ranging up to G miles from the dam site. For <br /> <br />the hulk of thc cmbankment matc'rials the haul distances would <br /> <br />average from one to one and one-quarter miles. Concrete aggregate <br /> <br />areas would be either the Cache La Poudre River at Greeley or Clear <br /> <br />Creek gravels in Denver. <br /> <br />Weld County Sites <br />----- <br /> <br />Because of the ultimate decision to concentrate the detailed <br /> <br />:~ <br /> <br />investigations all the lowel' Weld County axis, only a 1Jri"f summary <br /> <br />of the uppel' Weld County and the Osborne sites is given below. <br /> <br />;- <br /> <br />The balance of this report will deal with the lower Weld COWlty <br /> <br />si te and compar isoH of it with the Karl'ows site. <br /> <br />Weld County Upper Site <br /> <br />A eomprehensi ve descr ipU on of the geo logy at the upper We ld <br /> <br />County site is difficult considering that only 3 holes were <br /> <br />drilled on an axis over 25,000 feet long. Based on these three <br /> <br />test holes, plus the projectiun of a fourth hole, more than a <br /> <br />mile from the axis, the U. S. Bureau of Rcclalr,ation prepared a <br /> <br />generalized geologic scctirnl for ua'in prcparing construction cost <br /> <br />. <br /> <br />estimatl's. <br /> <br />Surface outcrops, later revealed by reconnaissance in <br /> <br />the arca, suggested that some bedrock configuration and elevation <br /> <br />'i <br /> <br />chnng~s should be made. Subsequently, further study of this axis <br /> <br />was abandoned in favor of investigating the lower Weld Cuunty <br /> <br />axis. <br />