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I I I I I I I I I I I I I I I I I I I certain parts of the pipe will flow as an open channel at atmospheric pressure; without vents, air aCcumulation or vacuum problems will occur. The need and location for vents will change with flows; i.e., a section flowing full may flow at atm()spheric if flows drop and vice versa. It may be better to oversize so the pipe always flows partially full under all flows. b. C:q>acity bll'll'n on flattest slQpf> The flattest section in the profile selected is used to calculate the minimum capacity of the pipeline. Under this concept, there would be no surcharging; however, vertical air venting pipes would be needed at locations along the pipeline to balance the air pressure in the system. This approach. is the safest, but it may also require the largest pipe diameter. c. ~"" c.apacity on slQpes greatl'r than flattest slQpe. Under this concept, some of the flattest slopes would flow full, and some water would have to back up into a steeper section above. Thus, some surcharging would <lCCur; however, this could be acceptable as long as their locations are known and the vent pipes are properly located. 3. Limitations on Analyses. Since calculations were based on slopes measured off of a USGS map, all flow analyses must be considered approximate. During fmal design, a profile of the pipeline will be made using an on-site survey and pipe diameter calculations made at that time could differ from those shown herein. As a safety factor, it was decided to base the preliminary design of pipe diameter on the flattest probable slope; i.e., one that did not create any surcharging. 4. Calculation and Cost Estimates. Since both the calculation and COst tabulation are relatively involved, detailed data for both is included in the Appendix (part .J2.J, rather than the main text. Results are summarized under each Alternative Analysis Section. 5. Pipeline Si71!S Reqllired to Meet Demand - Non-Pressure Flow. a. Demand Scenarios. As discussed in Section B, there are four demand scenarios being considered as follows: Normal Operation Palisade alone Palisade & Ute - 3.3 MGD (Scenario A) - 3.3 MGD + 0.5 MGD - 3.8 MGD (Scenario B) EmergenGy Operation Palisade & Ute - 3.3 MGD + 4.0 MGD = 7.3 MGD (Scenario C) - 3.3 MGD + 10.0 MGD = 13.3 MGD (Scenario D) V-12