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<br />SECflOl'\ V <br /> <br />During the course of this study, numerous components of the existing stotm drainage system <br />were found to be inadequate. Some of these inadequacies are due to recalculated peak <br />flows determined through the use of new design criteria and development within the basins. <br />Other problems could be attributed to inadequate maintenance an(! previous polley. These <br />problems, compounded by the increased flow projections, add to the inadcquacy of the <br />existing system. The following sections of this report discuss those inadequacies and offer <br />recommended solutions. The preliminary designs completed in this Drainage Master Plan <br />for recommended improvements to drainage facilities have been based on guidelines within <br />the Teller County Drainage Criteria Manual ("Areawide Urban Runoff Control Manual" <br />prepared for the Pikes Peak Area Council of Governments by Gilbert, Meyer and Sam.'>, <br />Inc., 1980). <br /> <br />HYDRA lUeS <br /> <br />There are currently many drainage facilities within the corporate limits of Cripple Creek. <br />They are, for the most part, culverts and short sections of drainage conduit used to transport <br />drainage flows under major facilities such as streets, highways and railroads. As such, they <br />were installed to solve specific and isolated drainage prohlems. Most facilities were <br />installed many years ago and were not designed to account for infreq uentpeakflowrates. <br /> <br />Existing drainage facilities were evaluated on-site to determine dimensions and physical <br />condition for incorporation into this Drainage Master Plan. Exhibit 2, "Drainage Structures", <br />and Exhibit 3, "Bennett Avenue Storm Sewer System," indicate the location of existing <br />drainage structures. The information contained in Appendix C incorporates the results of <br />a field teconnaissanceeffort into locating and determining sizes an dconditionsofexisting <br />facilities. Table 5 in Appendix B, "Existing Drainage Structurc Evaluation", indicates the <br />estimated capadty of each existing structure and thc required design intlo wrate. <br /> <br />During preparation of the Flood Plain Management Study by the Soil Conservation Service, <br />a flood plain map for the City of Cripple Creek will be prepared. In negotiations with the <br />Soil Conscrvation Service and the Colorado Water Conservation Board, it has been agreed <br />to preparc the flood plain mapping to include any structure improvement> made during the <br />calendar year, 1992. An additional analysis will also be performed which will map the flood <br />plain hased on all recommended improvements. This procedure will allow a comparison <br />of the existing flood plain versus the flood plain limits once all recommended improvements <br />arecompletcd. <br /> <br />To determine the adequacy of the existing facilities, aad to develop a new system which will <br />conform with this master plan, the design capacity of each existing structure was calculated. <br />Hydraulic Engineering Circular No.5, "Hydraulic Charts for the Selection of Highway <br />Culverts", publbhed by the U.S. Department of Commerce, Bureau of Public Roads was <br />utilized to estimate design capaeity of the existing strucmres. Drainagepatlernswerealso <br />studied to determine the suitability of existing drainagc facilities and the need for new <br />facilitie.. At the time of detailed design of any improvements, final design anal}'sis may <br />reslIltindctcrminingthathydrauticconditionsareslightlydifferentthen represented here. <br />The city should plan to take that into account when reviewing and approving final <br />construellonplans. <br /> <br />V-I <br /> <br />v-, <br />