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<br />capacity of these facilities will be updated during the Alternatives Development Report. The <br /> <br /> <br />drainage facilities downstream ofMain Street do not have the capacity to convey the 50-year flood <br /> <br /> <br />event. The stonn sewer should be able to transport the lO-year flow, <br /> <br />In general, the drainage facilities along Mill Street also appear to have sufficient capacity to <br />convey the 100-year flood, The exceptions would be Reach D (Cooper Street) and the Reach J <br />(Mill Street downstream of Bleaker), The stann sewer system's capacity in this reach is very <br />variable. It's capacity ranges from the lO-year stonn event to greater than the 100-year flow; <br />although, it is doubtful that the higher capacities are actually achievable due to the very high <br />theoretical full flow velocities in the stann sewers, <br /> <br />The Garmisch Street conveyance system appears ta be undersized, Depending on the reach, it will <br />not pass runoffbetween the 10- year to 50-year event without flooding, The stann sewer, by itself, <br />does not have the capacity to pass even the 2-year flow, <br /> <br />The Francis Street drainage system will not pass the 50-year flood without flooding, The stann <br />sewer system will not pass the 2-year flow in the upstream reach, but it will pass the 5-year flow <br />in the downstream reach, <br /> <br />The outlet ofthe Francis Street and Garmisch Street systems (Reach S) is greatly undersized and <br />cannot convey even the 2-year flood event. There is no street flow in Reach S. <br />Table 8 provides a comparison and summary of the analysis of the existing flow and the existing <br />drainage system capacity, <br /> <br />G. DISCUSSION <br />The calculations shown in Tables 6, 7, and 8 provide a general analysis of the drainage facilities <br />in the City of Aspen. A more detailed analysis may reveal that the drainage system is limited even <br />further. This analysis did not consider debris in the runoff. If debris is transported by the runoff, <br />the capacity of the stann sewers and streets will be reduced, The inlets to the stonn sewers may <br />also be a limiting factor in some areas for the capacity of the stann sewer system, Our analysis of <br />the stann sewer system assumed that the pipes would be flowing full under the given conditions. <br />In reality, the extremely high velocities in some of the stann sewers will create a high hydraulic <br />head requirement that will limit the amount of flow entering the stonn sewer, The stonn sewers <br /> <br />6 <br />