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<br />0468 <br /> <br />. <br /> <br />".: ; -, . . .-. , <br />'deSi!5ned,toPT,oVd.de 'praetica:llycompleteprotection froinall floods up <br />to the standard proJect flood dr6~46 inches of runoff . 'Hydrologic <br />studies show that the r~quired storage for c,ontrolof the standard <br />, project qood is about 361 acre..feet, the adopted flood-control storage. <br />In order ,to insure ,li.' high degree of security against failure of the dam, <br />an uncontrolled spillway ogee weir', 75 feet wide, would be provided in <br />the left abutment.' A spilh/aY design flood with a peak discharge of <br />3,360 cubic feet per ,second and a volume of 10.0 inches of runoff was <br />developed and routed through the reservoir to determine the maximum <br />water surface. The maximum water surface e lev.a.ti on resulting from this <br />routing was computed to be 6215, with a peak discharge mf 2,500 cubic <br />feet per second. A freeboard of3 feet was adopted, establishing'the <br />,top of the dam at elevation 6218, <br />. ,\ . <br /> <br />5-03. Geological and fOundationconditiGlns. '- The Pinon Canon Dam <br />'site is locat,ed in the transitipnal zone of the highlands which form the <br />ea~tern slope of the Rocky Mountains. . In this region the geological <br />l'ormations are sedimentary- beds of cretaceous period consisting of <br />carbonaceous shales and sandstone's.' Fieid investigations of the site <br />and laboratory tests pf foundation materials obta~ned qy subsurface <br />exploration show that foundation conditions at the dam site would 'be <br />suitable for construction of an earth-fill dam. A geologic section of <br />the dam site is shown on plate 3. <br /> <br />. <br /> <br />5-04; General design crit,eria a.n4 assumpti'ons. - The embankment, <br />hydraulic, and structural design of the project structures are all in <br />accord with recommended practices. Design procedures and methods util- <br />ized are baseq. on theoretical and,empirical analyses in general use, <br />supplementeQ.,by results of model studies for siinilar structures under <br />comparable' conditions. Design criteria and assumptions used are out- <br />, lined inappend1x II of this' report. <br /> <br />VI '- DESCRIPTION OF PROPOSED STRUCTtiRES 'AND IMPROVEMENl'S <br /> <br />6-01,. Dam. - The detention dam would 'be a rolled-earth fill, <br />675 feet long with a crest width of 15 feet, and rising about 67 feet <br />above the arroyo bottom. The upstream embankment ,side s19pe would be <br />1 on 2.5 from top of dam (ehvation 6218) to elevation 6198, and <br />1 on 3 belowe;Levation 6198, . I)ownstream s,ide slope would be 1 on 2.5. <br />Slopes both up'streanianddownst1Hr'Jlll,wo-uld be protected by a grass cover., <br />The emJ:>~l'lkn!ent'sectionwould be constructed of impervious random fill <br />obtained from borrow pits in the r\lservoir area. Embankment stability <br />analysis qy the critical circle method indicated the factor of safety <br />against sliding to be about .1.50 downstream and about 1.19 for upstream <br />sudden, drawdown conditions. The general plan, typical sections, and <br />details of the einbarikment' are showl} on I?lates 2 and 5. <br />o.i"'!"" <br /> <br />. <br /> <br />t <br />~ <br />. <br /> <br />-5- <br /> <br />1; ,";....;" <br /> <br />