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<br />Further downstream, a grass-lined bypass channel and new 12.5' x 6' <br />box culvert under LeMay Avenue was designed to eli~inate the flood <br />potential 'in Alta Vista. The channel was sized to C<lrry the residual <br />lOO-year flow of 650-cfs. <br /> <br />The recommended order of priority was established based on anticipated <br />flood damages, improvement effectiveness and total system effectiveness. <br />Upon completing all six phases of the proposed plan, the total system <br />will be completed awaiting development and implementation of drainageway <br />planning in the open areas. <br /> <br />Shown on Sheet 9 are improvements around the Valley Airpark necessary <br />to carry the lOO-year residual flow of l,lOO-cfs. Improved double <br />F'e \ <br />7' x 12' concrete box culverts were designed for the airport runway <br />and two local streets. A grass-lined open channel was sized for the <br />areas between culverts generally following the existing creek bed. <br />The Cache la poudre Reservoir Intake Canal was routed through a <br />siphon where it crosses Dry Creek. <br /> <br />The first priority item, the channel diversion to the poudre River, <br />is essential to study area downstream of Larimer-Weld canel. <br />Improvements downstream were sized for the residual 100-year storm <br />event with the diversion in place. Items 2 through 5 are ordered <br />as they progress upstream. Implementation in this order eliminates <br />the concentration and eventual release of flood waters on a developed <br /> <br />area downstream. <br />than that normally <br />least dependent on <br />implemented at any <br /> <br />Concentratec flood water would cause greater damage <br />expected from shallow flooding. Item 6 is the <br />the other proposed improvements and could be <br />point in the process of construction. <br /> <br />Improvements were required in terms of a transition inlet to the <br />existing box culvert under ColoradO Highway 14. Flows would be <br />accelerated into the box in a concrete flume to make full use of <br />the existing culvert capacity. Even with this increase, only 1,100-cfs <br />of the lOO-year digcharqe of 1,400-efs can be acc~dated hy this <br />facility. <br /> <br />Table xv <br /> <br />p~, IMPLEME~TATIO~ PRIORITY <br /> <br />~ Implementation <br /> <br />Priority <br /> <br />Description <br /> <br />'fot<ll <br />l'ro;ect Cost * <br /> <br />The recommended drainageway improvements outlined can be implemented <br />as one project or can be divided into several projects. Within the <br />study limits, all of the proposed improvements need to be constructed, <br />although the nepn for some is greater than others. Table XV lists thc <br />recommended priority ~nd order of impl~mentation for a pha~ud schedule <br />of construction along with the estimated cost for each priority item. <br /> <br />1 <br /> <br />Diversion from Ldrimer-Weld Co~nty <br />Canal to poudre River <br /> <br />$1,152,000 <br /> <br />2 <br /> <br />College Avunue culvert im,n'ovements <br /> <br />617,000 <br /> <br />> <br /> <br />^lta Vista ~rea improvements <br /> <br />779,000 <br />67,000 <br /> <br />4 <br /> <br />vine Road culvert <br /> <br />, <br /> <br />Valley Airpark improvements upstream <br />and downstt-ear" of liighway 14 <br /> <br />1,749,000 <br /> <br />, <br /> <br />Meadow Ldll'-' culvert and minor ch<:lnncl <br />improvements in Reach A <br /> <br />37,000 <br /> <br />$4,401,00Cl <br /> <br />- 46- <br /> <br />* Costs include construction, <br />FLl\ and 0 & H. <br /> <br />right-of-way, engineering contingency, <br /> <br />- 47 - <br />