FLOOD06450 - Laserfiche WebLink

Home Browse Search

I I SECTION V I PHASE A ALTERNATIVES TABLE V-l ALTERNATIVES INVESTIGATED I The economic investigation of feasible alternatives is made by a factual analysis of the various costs and benefits associated with possible alter- natives, with careful consideration given to the input of the various entities involved. The approach taken during Phase A was to use entity input and past experience to identify the alternatives for each reach which may be feasible. The resulting alternates are evaluated as to their measurable benefits and costs as described in the following section. Reach Location RALSTON CREEK I Clear Creek Confluence to Pierce St. (Arvada) I Minor channel encroachment allows the use of soft lined channels These results can then be subjectively analyzed considering intangible bene- fits and neighborhood desires, implementation capability and political con- siderations to choose the alternatives for each reach which are most desir- able from the standpoint of the policy bodies for each entity. As long as the chosen alternate is technically practical, it is not necessarily desir- able to use the alternative with the highest benefit cost ratio, and as long as the chosen alternate is economically practical, this decision lies with the local government. In other words, it is reasonable to select an alternate which generates the greatest social, environmental, and recreational benefits even though the quantifiable Benefit/Cost Ratio may not be the highest. 2 Pierce St, to Garrison St. (Arvada) Medium channel encroachment led to investigations of soft lined and European-type channels I I I I Most of the impacts of urban development have an effect on the storm runoff system. It is important to recognize, while attempting to integrate the multitude of requirements for the urban system, that the major drainage system will operate whether or not it is planned or designed, and whether or not urban development is wisely located with respect to it. Thus, major drainage should be given a high early priority when considering the urban system so that storm runoff is handled as an asset and not a liability. It is important that the design criteria be well-conceived to maximize the benefits to be obtained from each alternate and to insure that the major drainage system will operate as intended. 3 Garrison to Leyden Confluence (Arvada) Heavy channel encroachment necessitated investigating both soft and hard lined channels I I f'~ I The design criteria used for this storm drainage planning study are those contained in the Denver Regional Council of Governments' Urban Storm Drainage Criteria Manual, Volume Nos. 1 and 2. 4 Leyden Confluence to Xenon (Arvada) Medium channel encroachment led to investigations of soft 1 ined and European-type channels. I The Table V-I shows the alternates which were investigated for the various reaches of Ralston and Leyden Creeks during Phase A. A complete description of the alternates may be found in the Phase A Report. I I 5 Xenon to State Highway 93 (Jefferson County) Open rural areas allow for non- structural alternatives I I I V-I Alternatives a} Status Quo Alternative b} Status Quo (flood plain) approach with limited struc- tural improvements c} Grass-lined Channel d} Nonstructural Strategy a} Status Quo Alternative b} Status Quo (flood plain) approach with limited struc- tural improvements c) Grass-lined Channel d) European-type Channel e) Nonstructural Strategy a) Status Quo Alternative b) Status Quo (flood plain) approach with limited struc- tural improvements c) Grass-lined Channel d) European-type Channel e) Concrete-lined Channel f) Closed conduit g) Nonstructural Strategy a) Status Quo Alternative b) Status Quo (flood plain) approach with limited struc- tural improvements c) Grass-lined Channel d) European-type Channel e) NonstructuralStrategy a} Status Quo Alternative b) Status Quo (flood plain) approach with 1 imited struc- tural improvements c) Nonstructural Strategy