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I I I I I I I I I I I I I I I I I I I l6 5. Provide flow separation structures at all irrigation ditches. area. It requires that a Flood Hazard Area (all area subject to inundation in a lOO-year flood) be divided into a High 6. Provide appropriate maintenance access to all improve- ments and open channel reaches. Hazard Area and a Low Hazard Area. The High Hazard Area is 7. Provide velocity control structures where excessive velocities and/or sustained low flows would cause channel side slopes to erode and/or the stream bed to degrade. one in which "flood flow velocities of four feet or more per second or flood depths of two feet or more would occur during a lOO-year frequency flood." The resolution directs that major Lakewood l. Provide a detention pond at l3th and Carr. Pond design shall be coordinated with and approved by City of Lakewood Parks and Recreation Department. facilities in obstructed portions of existing developed areas should "accommodate a minimum of lO-year storm flows without 2. Provide major drainageway improvements within the City of Lakewood in accordance with the enclosed proposed policy: "Resolution Defining A Planning And Design Criteria For Drainage Facilities In The City Of Lakewood." placing any building or structure within a high hazard flow area during a lOO-year storm." The resolution also directs that natural drainage channels in unobstructed areas should not be restricted by future development which would leave them unable Denver l. Provide selectee structural channel improvements for a lO-year flood consisting of the following items: to convey the 100-year flood. a. Channel shaping b. Drop structures c. Maintenance access In conformance with these criteria, lO-year facilities were 2. consideration should be given to the feasibility of a lined low flow (trickle flow) channel. designed in the City of Lakewood, the residual flood plain which would occur in a lOO-year flood was determined, and the 3. The structural stability question raised during Phase A for the very high embankment over the box culvert under Perry Street should be addressed and answered during Phase B. buildings which, after construction of the facilities, would remain in the High Hazard Area were delineated. A meeting was then held to determine if, in any case, facilities with capa- The "Resolution Defining a Planning and Design Criteria for cities greater than the lO-year flood should be planned in order Drainage Facilities in the City of Lakewood" referred to above to remove the affected structures from the High Hazard Area. In is a detailed document which was prepared after the Phase A general, the construction of lO-year facilities removed most report. The Resolution attempts, in part, to define an orderly buildings from the High Hazard Area, and removed many from the approach for planning facilities in a highly developed urban Flood Hazard Area. The High Hazard Areas which would exist after construction of future facilities are not illustrated within this report; actual future construction could substantially alter those areas.