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conduit below. The capacity of this inlet is inadequate and the inlet should bc replaced with a new structure. This new inlet should have approximately 6 square feet of open area and be installed in a condition allowing for a minimum of l+foot of ponding depth ahovethegrate. The di~cussi(ln in Section D, Upper Cripple Creek, concerning development of the Cripple Creek channel ben.veen structures holds true for tbis portion of the watersheda~well. Also, the designguide1ines presented in Section C, Second Street Tributary, concerning design guideline~ for the storm sewer system in Bennett Avenue hold true for storm sewer systent~ in this portion of the watershed. The following recommendations are made for improvements to existing structures within the basins associated with Cripple Creek and its tributaries. 6. A new buried conduit is required in the area between existing structur eno.50 and existing inlet no. 104. As previously discussed, once flow enters a conduit, tbe conduit size can be reduced because headlosses associated with entrance conditions are eliminated. It is recommended that approximately 150 lineal feet of 6o-inch RCP be installed at a slope of approximately 4%. Recommendations for replacement of the remainder of tbis existing conduit will be discussed in Section E, Cripple Creek and Tributaries, of this report. E. Cripple Creek and Tributaries 1. Existing structure numbers 105 and 106 are inadequately sized conduits in extremely poor condition which convey flow from tbe Main Street Tributary into the conduit wbich intercepts flow from Upper Cripple Creek (location of existing structure numbers SO and 104). The runoff associated with the 100- year design storm event at this location is 605 CFS. To adequately intercept lbisrunoff,it is recommended that an ll'5"x 7'3" areh culvert complete w ith headwall, wingwalls and a minimum headwatcr depth of 8'6" be installed. Once the runoff is intercepted by this arch culvert, the conduit size can be reduL'Cd to 60-inch RCP at a minimum slupe of 5%. Approximately 125 lineal feet of60-inch RCP is required. Cripple Creek and its tributaries, as defined herein, begins at the lower end of Upper Cripple Creek. Cripple Creek flows southwesterly from this point to the conflucnce of Poverty Gulch. Cripple Creek then continues to flow in a southwesterly direction through the soU!heasterly portion of the city's corporate 1imits to its confluen ccwith the Second Street Tributary and the Thurlow Avenue Tributary. At this point Cripple Creek turns and flows in a southerly direction until it leaves the city's corporate limits. Structures within Cripple Creek and its tributary hasins are included in two general categories. The first category is major structures in thc Cripple Creek channel at road crossings. These s1nletures appear to be severely undersized and are in nced of replacement. The second category of structures primarily deals with inlets and storm sewer components within the business district. Again, a majority of these structures arc severely undersized and in need of replacement. 2. ExL~ting structure no. 46 is a continuation of the conduits described above. As Cripple Creek and the Main Street Tributary have combined at this p()int, the design runoff ass()ciated with the loo-year design storm event is 1,1\17 CFS. As with existing structure numbers SO, 105 and 106, existing structure no. 46 is in extremely poor condition and needs 10 be replaced. [t is recommended that this structure be replaced with a 72-inch RCP at a minimum slopc of 7%, Approximately 450 lineal foot of 72-inch RCP will be required. As an alternative, an open channel approach could he considered. However,because U1eadjacent land uses have enjoyed the use and bencfit of the available land over the existing conduit, it would be a major change in design and use for the adjacent bw;incss properties. VI-15 Vl-16