Laserfiche WebLink
pipeline does slightly increase the pumping head required at low flow rates. However, the <br /> pumping head requirement is not increased when the entire length of the pipeline is flowing <br /> full at the higher flow rates. <br /> The second factor considered in the proposal to route the pipeline to the top of the <br /> knoll was based on possible future tailing deposition on Robinson Tailing Pond. Although <br /> this may be a remote possibility, the expense of possible future realignment of the pipeline <br /> would be minimized with the vault located at the high point as shown. <br /> From the vault at the crest of the knoll (sta. 29+00), the pipeline drops down and <br /> crosses the west end of Robinson Tailing Pond. There is an area just below the knoll that <br /> will require approximately 3,000 cubic yards of fill to maintain a negative pipeline slope <br /> from the vault on the knoll to the pipeline discharge. The profile of the route shown on the <br /> drawing is such that the first 2,900 feet of the pipeline will drain from the knoll back to <br /> the pump station, and the rest of the pipeline will drain from the knoll to the tailing ponds <br /> when the pipeline is taken out of service. However, due to the flatness of the surface of <br /> the tailing pond, the slope of the pipeline across the tailing pond is very flat and will require <br /> accurate installation in order to maintain the grade required to drain the pipeline. There is <br /> a possibility that settlement of the tailings could occur in the future, especially if additional <br /> tailings are deposited over the pipeline. Settlement would cause low spots to form along <br /> the pipeline that could lead to future freezing problems. However, the tailing pond has <br /> been in its current configuration for many years which would indicate that primary <br /> consolidation has already taken place. <br /> A second vault would be located near the west abutment of No. 2 Dam at <br /> approximate station 47+50. A,second vent would be located in this vault to prevent <br /> vacuum pressures and to stabilize the flow conditions in the pipeline. Two knife-gate <br /> valves would also be located in this vault which would be used to direct the flow to <br /> discharge to either Tenmile or Robinson Tailing Ponds. A pipeline cleanout access port <br /> would be located in this vault. <br /> 18 <br />