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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />No Action: <br /> <br />Due to current deterioration of the existing diversion wall, it is now inadequate to protect <br />the highway, pools and adjacent public facilities against damage due to flows <br />overtopping or breaking through of the wall. Risk of overtopping and/or failure in a <br />major storm event is considered high. Failure of the existing wall increases the hazard to <br />the pools as not only would the natural flows and debris be deposited in and around the <br />pool facility but also the wall material (rocks, timber, fencing and miscellaneous <br />construction materials) would be added to the flow. No report of personal injury was <br />made following past facility damage due to Skyrocket Creek flows, but a risk for injury <br />or loss of life exists if advance warning of the flood event and wall failure is not <br />available. The No Action alternative is not a viable plan due to risk to life and property . <br /> <br />Reconstruction of Diversion Wall <br /> <br />Sub-alternatives were considered in conceptual design of the wall reconstruction that <br />included: <br />a) rock-filled steel crib wall <br />b) reinforced concrete wall <br />c) gabion wall <br />d) stone and masonry gravity wall <br />e) concrete wall with tensioned anchors. <br /> <br />Buckhorn Geotech developed the first three of these sub-alternatives in 1990 for the City <br />of Ouray. The walls were to span approximately 35- feet with a height of approximately <br />I2-feet to tie into adjacent bedrock at each end of the diversion wall. The recommended <br />alternative was the rock-filled steel crib wall due to on-site availability of rock material <br />and durability of construction. Preliminary construction costs were updated December <br />2000 to give a total of $67,600. Adding a IS-percent factor ~r engineering and a~ <br />percent contingency gives total estimated costs of$87,88~ t ;}(!), ()OO 30 - <br /> <br />The stone and masonry gravity wall alternative was developed by Ayres Associates for <br />the U.S. Army Corps of Engineers (under subcontract with Jones and Stokes and <br />Associates) in 1997. This wall was proposed to span approximately 30-feet and be a <br />maximum height of 1 O-feet to contain the estimated 100-year debris flow. The report <br />notes that the one reason for selection of this type of construction over the previous <br />recommendations was to utilize on-site rocks, limiting the need to haul construction <br />materials to the remote site. Preliminary construction costs were estimated at <br />approximately $ 50,000 at that time. Using a 5% inflation per year gives an estimate of <br />construction costs in 2001 of$60,775. Adding a IS-percent factor for engineering and a <br />-tJ"-percent contingency gives total costs of $-79,9e8.}/ 'J (f), (000 <br />30 <br /> <br />The alternative for construction of a concrete wall with tensioned anchors, was developed <br />by the U.S. Army Corps of Engineers (USACE), Sacramento Office, for City of Ouray in <br />2000. Preliminary construction costs were estimated at approximately $ 300,000. This <br />wall is approximately 35-feet in length with maximum height of 10-feet. <br /> <br />7 <br />