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3 Hazard Classification and Dam Size <br />~ Irt 1980, Monument Dam was classified by the U.S. Army Corps of Engineers (IJSACE) Phase I <br />inspection program as a Class I, high hazard dam. A high hazard dam, according to the rules, is a <br />dam for which loss of human life is expected to result from dam failure. In 1981, after a more <br />detailed review, the hazard classification was changed by the SEO to Class II, or significant hazard. <br />Hazard Class II is defined by SEO Rules and Regulations as "a dam for which significant damage is <br />expected to occur, but no loss of human life is expected from failure of the dam. Significant damage <br />is defined as damage to structures where people generally live, work, or recreate, or public or private <br />facilities exclusive of unpaved roads and picnic areas. Damage means rendering the structures <br />' uninhabitable or inoperable." The current dam hazard classification of Monument Dam is Class II, <br />or significant hazard. <br />However, the SEO has recently performed a visit to the site and identified two downstream structures <br />that could cause DWR to revise the hazard classification of the dam. This requires the performance <br />of a hazard classification study which includes a dam break analysis. The performance of such a <br />study by the SEO is still pending and therefore an alternative design strategy was proposed to the <br />DWR by MCRC and MCC. That alternative assumes that the dam is classified as high hazard as <br />defined by the State of Colorado Rules and Regulations. The DWR approved the approach and its <br />confirmation letter is included in Appendix B. <br />The jurisdictional height of Monument Dam was determined to be 50 feet, resulting in a small size <br />dam as defined by the State of Colorado's Rules and Regulations for Dam Safety and Dam <br />Construction. A letter from the SEO confirming the dam size is included in Appendix B. <br />In summary, the design of the modification to Monument Dam presented herein assumes the <br />Monument Dam is a small size, high hazard dam as defined by the State of Colorado's Rules and <br />Regulations for Dam Safety and Dam Construction. <br />P:\Mpls\06 CO\26\0626067\WorkFiles\DesignReport\FINAL\DesignReportFINAL.doc 4 <br />