FLOOD08407 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I There are two stretches of channel in reaches 1, 2, and 3 of the proposed plan that have no maintenance road. The lower stretch is the concrete channel extending from West 64th Avenue to the channel's confluence with Clear Creek. This area is accessible from the railroad service trail that parallels the channel. The unimproved channel section that traverses an undeveloped lot from above Winona Court to West 75th Avenue comprises the second stretch without a maintenance road. The maintenance road should be constructed in this section when the adjacent property is developed. A maintenance road will for the most part parallel the Shaw Heights Tributary from where it surfaces near the Colorado and Southern Railroad tracks to the confluence with the main stem. The two stretches of channel with no maintenance road are concrete-lined and accessible from adjacent parking lots. The maintenance road along the Shaw Heights Tributary is situated outside the flow area of the channel. The previously improved channel stretch below West 80th Avenue and the location of the channel primarily on public lands makes this configuration feasible. Easement for access will be required, however, from the railroad and adjacent property owners. Where a maintenance trail is to be constructed, vehicular maintenance access points are to be provided at regular intervals near selected street crossings. Formal maintenance easements should be obtained for all reaches of the channel whether or not improvements are to be constructed. Water Quality Except for possibly the period during construction, the improvements to the channel and related structures will not have a detrimental impact on the water quality of Little Dry Creek. In fact, some removal of pollutants will occur naturally as a result of these improvements. Drop structures, energy dissipators, and grass-lined channels which foster the growth of aquatic plants and animals all tend to help aerate the water and maintain the dissolved oxygen concentrations necessary for the elimination of organic compounds. Drop structures and channel linings reduce erosion and consequently the suspended solids load. Detention ponds provide the stilling effect necessary for suspended solids to settle out of the stormwater. Control of pollution beyond the capacity of the natural purification processes present in Li ttle Dry Creek will require supplemental study and is beyond the scope of this report. Each jurisdictional entity should be involved in setting Objectives and strategies for embarking on a water quality management program. The tools for reducing stormwater pollution, from enforcement of Ii tter laws to installation of complex water treatment facilities, do exist and are constantly being improved upon and increased in number. \l - 3 Parks and Recreation The improvements for Little Dry Creek will help serve both the regional and neigh- borhood needs for open space and recreational opportunities. Nearly 3.5 miles of continuous hiker/biker/maintenance trail are proposed. Beginning near 80th Avenue on the Shaw Heights Tributary and interlinking with the City of Westminster's proposed Wolff Run Park, the trail would extend uninterrupted to below Federal Boulevard on the main stem. The grass-lined channel which is paralled by a hiker/ biker maintenance trail would improve the visual impact of the local environment and would be usable as a local recreation belt along the improved reaches of the main stem. Only slight reshaping of the channel is necessary to convey the 100-year storm through the 80 foot width allotted the drainage channel in the proposed Wolff Run Park in Westminster. The enlarged detention pond on the Shaw Heights Tributary just east of U.S. 36 would remain an excellent multi-purpose facility. Further upstream, the area proposed for a detention pond would be well suited for a small neighborhood park, as it would be inundated only during major storms. Acquisition of the public right-of-way in the floodplain of reaches 4 and 5 cannot be economically justified from a flood control standpoint, but purchase of the same for parks and recreational purposes may be viable. Arvada is presently considering purchasing the Pomona Lakes 2 and 3 detention pond just north of West 80th Avenue in Reach 5. This facility should provide excellent parks and recreational opportunities and would tie in nicely in to the existing and proposed hiker/biker/maintenance trail system on Li ttle Dry Creek Administration In reaches 1, 2, and 3, a majority of all proposed channel improvements are designed for the 25-year storm or less. Regulation of the 100-year floodplain in all reaches is a necessary aspect of the plan to offset the residual flood damage caused by larger floods. Property owners affected by the existing 100-year floodplain should be encouraged to purchase flood insurance and residents within and adjacent to the 100-year floodplain should be notified annually of the potential flood hazards. After the master plan is implemented along any of the reaches, the regulation of the residual 100-year floodplain will become a subsidiary part of the improvements; that is, drainageway improvements sited to convey less than the 100-year flood will often result in a residual 100-year floodplain requiring regulation. Where development is forthcoming adjacent to the floodplain, the development should be monitored and controlled as it occurs so that the floodplain activities are compatible with the local long range land use plans and other state and local regulations. This includes the acquisition of maintenance easements and