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Chapter I - Introduction The State of Colorado, acting through the State Engineers Office (SEO), has determined that the spillway capacity at Left Hand Valley Iteservoir, located north of Boulder, Colorado, is inadequate and will not safely pass the runofffmm the 75 percent Probable Maximum Precipitation storm without overtopping of the dams. On October 3, 1991 the SEO ordered the Left Hand Ditch Company to increase the spillway capacity or be subject to a storage restriction. A copy of the order is included as Appendix A. The purpose of this feasibility study is to determine the most feasible method of increasing the spillway capacity at Left Hand Valley Reservoir. A non-structural plan and seven structural plans are examined for financial, technical and institutional feasibility. The non-structural plan is one of no action. The structural plans include widening the existing spillway, constructing a new spillway over the north dam, and providing complete overtopping protection for the north dam. For the new spillway alternatives both conventional formed concrete and roller cOmpacted concrete are considered. Roller compacted concrete is considered exclusively for the overtopping alternatives. In order to minimize the size of the spillway, and therefore the cost of the project, various means of raising the dams are discussed. Fuse plug embankment construction is considered in order to cause the existing spillway to be utilized for more frequent floods. The project will be financed through a loan from the Colorado Water Conservation Board and a bank loan. Repayment will be accomplished by charging increased assessments against issued share of Company stock. A financial analysis is presented showing the funding and repayment for the preferred alternative. 1 I I I I I I I I I I I I I I I I I I I