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COMMENTARY ON SHEET 2 The Engineering Staff at Adolph Coors Industries is presently conducting a detailed analysis of the impact of 100-year flooding on their facilities and will report directly to the appropriate Coors personnel on additional struc- tural or non-structural measures to be implemented. In the interim, the existing 100-year floodplain limits should be recognized and regulated and a flood emergency plan established. Emphasis should be placed on mobilization of debris removal equipment and short term floodproofing measures at criti- cal structures and equipment. It is important to note that the extent of flood i ng on Tucker Gul ch and Kinney Run are not wi thi n the scope of thi s study. However, the major drainageway plan for these tributaries is currently under study and will address them in detail in a separate report. I I I I I I I I I I I I I I I I I I I C-5 Portions of Reaches I and 2 Station 850+00 to Station 900+00 As described in the previous Commentary, 100-year flood flows would be con- fined within the improved channel constructed under the long term plan. Bridge improvements at Ford Street and Washington Avenue provide approxi- mately 2 feet of freeboard above the 100-year water surface. Implementation of the Long Term Plan will also require a berm or regrading of the Mitchell School area upstream of Ford Street, relocation of the Agricultural Ditch headgate structure and removal and replacement of the existing twin-tee wall along the north bank upstream of Ford Street. The long term channel in- cludes a maintenance/hiker/ biker trail with access points at Ford Street and Washington Avenue. Ultimately the Clear Creek trail will connect with the proposed Tucker Gulch trail as indicated at right. In the interim, the existing 100-year floodplain should be regulated, the Mitchell School and Annex buildings need to be floodproofed. The Ford Street and Washington Avenue bridges should be protected against impact curb buoyancy forces by additional tie-down anchorage at the bearing area for the precast tee units on the upstream side of each bridge, connections at the diaphragm and addi- tional connections at the top fl ange of the precast units on each bridge deck. Proper air venting of the bridge to prevent uplift should be provided by installation of small pipes to release air trapped under the bridge deck during a high flood flow. Maintenance access to the channel is avail able by the adjacent road and parking areas, however, there are no permanent ramps which allow equipment to access the channel bottom. It should be noted that Coors Industries has done an excellent job of maintaining the channel capacity throughout Reach 2, constructing temporary ramps into the channel when necessary. Since this maintenance strategy has thus far been satisfactory, construction of per- manent access ramps into the channel does not appear to be necessary. The recommended Long Term Plan for Reach 2 (Tucker Gulch to McIntyre Street) combines various structural measures to confine the 100-year flood flow within the channel area. Of primary importance is the removal or raising of bridges which extend into the channel area and restrict flow. Where indi- cated on Sheet 2, sections of the existing concrete channel wall should be raised to contain the 100-year flow. Surcharge protection (i.e., a flow re- strictor plate) should be installed at the entrance to the conduit which conveys the Farmers Highl ine Canal eastward through the Adolph Coors com- plex.