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I I I I I I I I I I I I I I I I I I I IV-4 will remain in place, will be rehabilitated and will eventually have the State Engineer's hold order restricting its storage capacity removed. Van Bibber Creek Reach V-I. This reach of Van Bibber Creek extends from the conf1 uence of Ralston Creek to Kipling Street. The channel flows beneath the Arvada Plaza Shopping Center parking lot in a 5' x 5' culvert, The capacity of this culvert is approximately 200 to 250 cfs. During floods, it is likely that the pipe entrance would be plugged with debris to such an extent that most flood flows would travel overland across the parking lot. Below the outlet of the box culvert, downstream of 58th Avenue, Van Bibber Creek flows through a small open channel to Ralston Creek which it joins at approximately a 90' angle. may be possible to decrease the number of box culverts to pass the new design flow assuming detention has been installed, Care must be taken to insure that the reduction in culvert size of the new Kipling Street cross- ing does not increase the flood hazards above historic levels to any pro- perties, Reach V-2. This reach extends from Kipling Street to Oak Street. This reach is characterized by divided flow between a new channel constructed north of 58th Street, with a capacity of approximately 1,000 cfs, and over- flow areas to the north and south of 58th Street. The new channel was con- structed with the assumption that the Ward Road Reservoir would be con- structed upstream, The Phase A portion of this study showed that alter- native to be uneconomical and it was not selected by the sponsors as part of the recommended plan. The inlet to the channel is designed to divert 1,000 cfs into the channel and any flows above this, into the newly con- structed baseball fields downstream. Reach V-3. This reach of Van Bibber Creek extends from Oak Street to Ward Road, The channel and floodplain are essentially in their historic state, with the exception of the soccer fields located near Simms. The soccer fields are constructed in the overbank and have not encroached on the existing mainstem of Van Bibber Creek. The soccer fields are the site of the Oak Street detention facil ity. Care has been taken to assure that the proposed improvements are compatible with the soccer uses. The Reno-Juchem Ditch crosses Van Bibber Creek in this reach. Runoff from the north tributary of Van Bi bber enters the main channel near the Reno- Juchem Ditch crossing. There is an area of shallow flooding downstream of the Reno-Juchem Ditch caused by overflow from the ditch during floods on the north tributary. A new a1 ignment for Kip1 ing Street has been proposed by the State Highway Department. A c1 uster of culverts has been proposed for thi s crossing of Van Bibber Creek. These culverts would consist of seven 6 foot x 13 foot reinforced concrete box culverts. These box culverts have the capacity to convey the entire future 100-year flood fl ows beneath Ki p 1 ing Street with an acceptable freeboard. Prior to final design and construction of the Kip1 ing Street crossing, it should be determined whether the recommended Oak Street detention facility will definitely be constructed. If so, it Reach V-4. Thi s reach extends from Ward Road to Ind i ana Street, the up- stream limit of study on Van Bibber Creek, This reach has only been sl ight1y altered from its natural state. There has been some housing development above Ward Road, but generally these do not infringe on the f1 oodp1 ai n. This reach also contains the special study area designated as 58th and Eld- ridge. This area experiences frequent local flooding problems and was analyzed separately during this study. No floodplain delineation of this area was performed, however, sufficient hydraulic analysis was prepared to develop recommendations for the solution of these local flooding problems.