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<br />1.0 INTRODUCTION <br /> <br />1.1 PURPOSE <br /> <br />The purpose of tltis report is to present a summary of the technical analysis, design <br />issues, and construction considerations for the design of modifications to Idaho Springs <br />Reservoir Dam, located in Clear Creek County, Colorado. <br /> <br />1.2 SCOPE OF WORK <br /> <br />The following scope of work was performed for this design: <br /> <br />I) A start-up visit with Construction Contractor <br />2) A site visit <br />3) A visit to State Engineer office in Greeley, Colorado <br />4) Field surveys and mapping to supplement existing data. <br />5) Analysis of structural, geotechnical, and civil engineering issues to support and <br />document the final design modifications. <br />6) Preparation of construction drawings, technical specifications. <br />7) Coordinate of the Design Summary Report. <br /> <br />2.0 BACKGROUND <br /> <br />2.1 PROJECT AND SITE DESCRIPTION <br /> <br />Idaho Springs Reservoir serves as a water supply for the town of Idaho Springs, <br />Colorado. The dam is located on Chicago Creek in Clear Creek County about 8 miles <br />southwest of Idaho Springs. Using tlIe State of Colorado criteria for Hazard <br />Classification, the dam is classified as a Class I and is considered to be sized as an <br />Intermediate Dam. <br /> <br />The dam is a homogenous earthfill embankment with a crest length of about 700 feet and <br />an embankment height of approximately 30 feet. The dam and reservoir has two <br />spillways. One is a rock masonry uncontrOlled chute located on the right abutment and <br />the other is a reinforced concrete uncontrolled side channel chute located on the left <br />abutment. The side channel spillway has an estimated capacity of about 5700 c.f.s. The <br />side channel spillway was constructed in the late 1970's, many years after the <br />embankment was built. It is assumed that hydrologic studies conducted in the 1970's <br />indicated that the dam was deficient in spillway capacity. During or soon after <br />construction of the spillway, concrete portions of the inlet structure showed signs of <br />distress and partial failure. Since construction, the structure has continued to deteriorate. <br />Because of the condition of the spillway and seepage problems associated with the <br />embankment, the reservoir has a restricted storage capacity. <br /> <br />1 <br />