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� <br />r <br />r <br />� <br />� <br />r <br />The pipeline will be buried with minimum cover of three feet above the crown of the <br />pipe. To assure integrity, the pipe will be properly bedded prior to filling the tr�nch with <br />well-compacted backfill. Sources of bedding material include off-site commercial sand <br />and gravel pits and processing of locally available materials. Decisions on bedding <br />materia! sources will be made during final design following g�otechnical field <br />investigations. Access manholes, air release valves, and drain valves will be provided <br />at appropriate locations along the pipeline, as determined during the final design and <br />confirmed during construction. <br />Pipe materials suitable for the project include polyvinyl chloride (PVC, C-900 and C- <br />905), steel, ductile iron, asbestos cement, and reinforced concrete pressure pipe. The <br />most likely type of pipe for the main conveyance alignment is PVC or steel. Further <br />review of pipe materials and prices will be made during final design. <br />� As discussed above, the pipeline will terminate at a river outlet structure. Upstream of <br />that structure, there will be a control valve to maintain appropriate velocities in the <br />pipeline. This valve will be locate just upstream of the outlet structure. An ultra-sonic <br />t flow meter wiN be provided approximately 30 feet upstream of the downstream control <br />valve. <br />� <br />' <br />' <br />' <br />' <br />� <br />i <br />4.10. Special Crossings <br />Depending on findings during the design-lev�l field reconnaissance, various types of <br />special crossings may be needed to route the pipeline over or under existing utilities, <br />under stream channels and wetlands, and urtder roads. No major stream, road, or <br />railroad crossings have been identified, and $pecial crossings are expected to be <br />relatively few in r�umber. Utility crossings m�y require special excavation methods and <br />encasem�nt of sections of the Comp�ct Compliance Pipeline. If per�nnial streams or <br />wetlands must be crossed, direetional borings and �asing conduifis may be used. <br />4.11. River 4utlet Structure <br />The outlet from the pipeline to th� North Fork wil! be a convEntional USBR-type impact <br />ba�in constructed of reinfprced cc�ncrete. Dimensions of the structure will be <br />approximately 11 fe�t (W) by 14 feet (L) by 7 feet (M). The structure will be set back, <br />and grading around tMe structure will be performed to minimize uisual impacts. With <br />discharge normally in the c�nge a# 20 #0 3Q cfs, the basin will discharge flow about equal <br />to and sometimes greater than the normal flow of the river. To avoid issues with <br />channel erosion, the ba�in discharge will be �ngled at approximately 30 degrees (or <br />less) to the river channel. <br />� The impact basin will be set back from the river at � location outside of #he estimated <br />1 AO-year flood plain, probably about 50 to 100 feet from tMe existing river bank. A <br />channel will be excavated from the basin to the river. This channel could b� engineered <br />1 to replicate the natural �Jorth Fork channel, thereby providing �n eventual net gain in <br />rip�rian habitat to offsEt the effects of exGavation of the new channel into the existing <br />river bank. <br />, <br />, <br />13 <br />