C153514 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I release of the collected flows through the partially rehabilitated outlet works. To minimize possible impacts to the partially completed work, we anticipate that the contractor will have sandbags available to block sediment flows into the ungrouted space between the steel plate tunnel liner and the existing tunnel. Following the passage of the collected storm flows, we anticipate that the contractor will rebuild the coffer dam, remove debris from the outlet works and intake area, and recommence the outlet rehabilitation work. Demolition of the existing intake structure will be required to facilitate insertion of the welded steel pipe liner section into the existing outlet tunnel and to prepare for installation of the new slide gate and air venting system. The new intake structure, slide gate system and air vent system are shown in relation to the rest of the outl et works system on Fi gure g and in more deta il on Fi gure 12. The grouted space between the welded steel plate liner and the existing concrete-lined tunnel will join the insert and the tunnel into a single structural unit to stabilize the outlet structure, sea 1 off the seepage and pi pi ng into the tunnel and fill the areas having a deteriorated tunnel floor. The relined outlet tunnel is shown schematically on Figure g and in more detail on Figures 10 and 11. The resultant outlet section and details are shown on Fi gure 12. The new outlet structure has been designed to provide sufficient outflow capacity to maintain the current maximum outflow rate of approximately 195 cfs at maximum pool elevation 8,264 ft, as measured at the weir located in Gurley Canyon just downstream of the dam. The engineering analyses used to evaluate the flow capacity of both the existing and rehabilitated outlet conduits are described and summarized in Appendix J. -23-