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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 />valve to allow releases back into Snowball Creek. Flow into the conduit <br />enters through an elevated intake structure with three trashracks. The <br />intake structure is fitted with a bulkhead slot to allow a bulkhead to be <br />placed if dewatering of the entire conduit is required. The invert of the <br />intake structure is approximately 20 feet above the stream bed to <br />accommodate the dead storage requirements for fish propogation. The intake <br />structure is connected by a vertical shaft to the main conduit whose intake <br />is at stream bed level. After diversion, this section of pipe will be <br />filled with concrete. The bypass piping connects to the service spillway <br />before dissipating into Snowball Creek. The bypass pipeline is capable of <br />delivering 46.5 cfs with 10 feet of head. Sheets 3 through 6 of the <br />drawings in Appendix B show the proposed design. <br /> <br />5.5 PIPELINE DESIGN <br /> <br />The proposed pipeline travels along the existing road from the dam <br />site to Pagosa Springs' treatment pond. The pipeline would consist of <br />26,000-feet of 18-inch pressure pipe that would be buried with a minimum of <br />4-feet of cover. The design capacity of the pipe is 15 cfs. Pipe drains <br />would be installed at the low points and air-vacuum valves would be <br />installed in vaults at the high points. Where possible, the pipeline will <br />be routed off the shoulder of the road to minimize replacement of road base <br />gravel. <br /> <br />The reconnaissance study discussed two options for delivering water <br />from the reservoir to the treatment plant. The first option consisted of a <br />continuous pipeline from the reservoir to the treatment plant. The second <br />option combined the use of 2.5 miles of open ditch or stream and 2.5 miles <br />of pipeline. An infiltration gallery or diversion facilities would be <br />constructed to collect flows for the pipeline under the second option. <br /> <br />The continuous pipeline appears to be the best long term option, even <br />though initial costs are higher. The combination ditch/pipeline has <br />several potential problems. In order to have enough head to deliver water <br />to the treatment plant, the infiltration gallery would have to be located <br />just downstream of the confluence of Four Mile Creek and Snowball Creek. <br /> <br />5-5 <br />