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Outlet Conduit Desiqn <br /> Precast reinforced concrete pipe was chosen for the outlet pipe. The pipe will <br /> consist of 24-inch diameter RCP, Class 5, with rubber gasketed R-4 joints with retaining <br /> groove. The pipe has been oversized in order to allow for physical access for inspection. <br /> The embankment loads for the concrete pipe were calculated in accordance with <br /> Marston's theory assuming an embankment unit weight of 135 lb per cubic foot. The <br /> precast concrete pipe shell and reinforcement is designed using the following loading <br /> conditions: <br /> Condition 1 W„ 1.8 <br /> Condition 2 W„ 1.25 + Wh <br /> where: W„ = Vertical Embankment Load (18,537 Ib/ft) <br /> Wh = Horizontal Embankment Load (6,173 Ib/ft) <br /> The reinforced concrete pipe will also be designed to withstand a maximum external or <br /> internal hydrostatic head of 45 feet. <br /> The 24-inch RCP will be placed on a 5-foot wide concrete cradle (Ref. Sheet 2). <br /> The cradle will have battered walls and will extend up to the spring line of the pipe in order <br /> to avoid difficulties of proper compaction of backfill under the pipe and against the cradle. <br /> Reinforcing bars for the concrete cradle are designed for shrinkage and temperature. The <br /> cradle shall be placed on undisturbed soil or, where over-excavation occurs,the foundation <br /> soil shall be compacted to 98 percent standard Proctor maximum dry density. <br /> Construction of the embankment was completed to its' existing height (elevation <br /> 10,725 feet) in July 1968. Construction documentation shows that most of the fill was <br /> compacted to at least 100% standard Proctor density during the construction process. <br /> Based upon the construction documentation and the fact that sufficient time (26 years) has <br /> passed to allow for consolidation, it was determined that the existing fill is sufficiently <br /> compacted to support the conduit without excessive settlement potential. <br /> 9 <br />