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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />1.0 INTRODUCTION <br /> <br />Co~anche Da~ is an existing earth embankment with a ~aximum height of 40 feet <br />and a crest length of about 1500 feet at elevation 9395 (Gage Height 40.0). <br />It impounds a reservoir, when full, of approximately 2,629 acre-feet at the <br />normal ~aximum water surface elevation of 9390 (G.H. 35.0). The reservoir is <br />located on Beaver Creek in Sections 11 and 12, Township 7N, Range 74W, 6th <br />P.M. in Lari~r County, Colorado. The dam is in Water Division 1, District 3 <br />and is identified in the Colorado State Engineer's Office (SED) inventory of <br />dams as Number 030121. The structure is owned by the City of Greeley, <br />Colorado (City) for ~unicipal supply. The location of COr.1anche Dar.1 is shOltn <br />on Drawing 2024-Gl. <br /> <br />The da~'s operating level has been restricted to elevation 9382 (G.H. 27.0) <br />since January 30, 1986 by the SEO. This restriction was imposed due to <br />excessive seepage and the potential for piping of foundation materials. <br /> <br />110rrison-Knudsen Engineers, Inc. (MKE) was contracted by the City in June of <br />1986 to study the feasibility of rehabilitating the dar.1. The study was <br />partially financed by the Colorado Water Conservation Board (CWCB). Based on <br />the recomendati ons on the feasi bi 1 ity study, MKE was awarded a contract for <br />final design in Septe~ber of 1987. <br /> <br />The following Final Design Report sUr.1r.1arizes the present condition of the dar.1 <br />and reservoir and presents geotechnical and hydrologic data developed during <br />the feasibility study and final design and outlines the rehabilitation <br />alternatives evaluated. The rehabilitation design criteria for the <br />er.1bankr.1ent, outlet works and spillway are established and a detailed narrative <br />description of the design is presented. Additional information on site <br />inspection, hydrology and geotechnical investigations is presented in <br />appendices to the Final Design Report. <br /> <br />The Final Design Report is a supplement to the technical specifications and <br />construction drawings. <br /> <br />2084H - 1 - <br />