FLOOD08479 - Laserfiche WebLink

Home Browse Search

8 From Belleview to Yosemite the gulch is still within Denver Technological Center property. The lOa-year flood plain through this reach is wide and shallow but well confined. Drawings G-ll and G-12 show this reach of the gulch. From Yosemite to Dayton Streetr the lOa-year flood plain passes through a large lot residential area. The crossing at Berry Street will be inundated during the lOa-year storm though none of the homes along the gulch are subject to flooding. Approximately halfway through this reach is the Orchard Hills Pond. This pond has no effect on the lOa-year flow as it will be overtopped during such an event. Upstream of Orchard Road, however, approximately 30 acre feet of ponding volume will provide a reducing effect on the flood flow north of Orchard Road. A similar ponding effect exists at Dayton Street; however, present plans are to eliminate this detention facility through development of the adjoining land west of Dayton Street. This reach of the gulch is shown on Draw- ings G-12 through G-14. Figure 15 provides a view of the flood plain area below Orchard Road. From Orchard Road to peakview Avenue, the flood plain is well de- fined, though narrow and shallow. The crossings at Caley and one other driveway crossing are inadequate for the lOa-year storm. The backwater elevations caused by these crossings will not have any effect on surrounding structures. Flood waters, however, will inundate two structures on the properties adjoining the gulch at East Fair Avenue. The potential depth of flooding at these structures is one to two feet. The flood plain on the West Tributary is shown on Drawings WT-l and WT-2. In the reach from Dayton Street to the upper limits of the study at Arapahoe Road, Drawings G-14 and G-lS, only one development, the Arapahoe Lakes Subdivision, has altered the natural flood plain. This subdivision is built around a lake which is sited on Goldsmith Gulch. The lake provides approximately 11 acre feet of flood storage and during a lOa-year event has little effect on the lOa-year flood flow in Goldsmith Gulch. The flood plain above Arapahoe Lake is shallow and generally less than 200 feet wide. southmo~r Park Tributary - The reach from the confluence of Goldsmith Gulch to the outlet of the 8' x 5.5' box culvert under Hampden Avenue passes through an apartment complex development. Portions of the flood flows will be carried in the long, concrete pipe under Poplar Street. The pipe, a 48" x 76" elliptical concrete pipe, will carry approximately 50% of the lOa-year flood flow, while the excess flows pass overland and around the apartment buildings. Shallow flooding will occur in the area around the westerly building presently under construction. The shallow flooding results from overflows from the main drainage course. Above Hampden Avenue, flood waters are detained in Southmoor Park and released through the pipe which serves as the park outlet. One building on Hampden Avenue may experience high water problems resulting from the stormwater ponding in the park. The lOa-year flood plain for the Southmoor Park Tributary is shown on Drawing SPT-l. West Tributary - The reach at the West Tributary from the Orchard Hills Pond to Orchard Road contains the lOa-year flood plain within a 200-foot limit. The narrow flood plain is a result of the detention characteristics of the Orchard Road ponding embank- ment. Presently only the tennis court located near the mouth of the tributary will be inundated during the lOa-year flood event. Flood Plain and Floodway Data The limits of future flooding for Goldsmith Gulch and the two tribu- taries are graphically outlined on the Flood Hazard Area Delination' Maps and tabulated in Tables 5 and 6, Flood Plain and Floodway Reference Data. The tables list the potential flood elevations, flood plain and floodway widths, floodway location, floodway sur- charge elevation and thalweg elevation at each cross section studied.