PDF - 9Mo - Grande Dixence SA

GD. P.41Arollapumping stationA high valley that is not… high enoughAt the end of the water collecting works, the high Arollavalley is still… too low. It is more than 300 m away fromthe crucial spot height of 2400 and the main water conduitleading to Lake Dix.Arolla receives the water already pumped by Ferpècleand adds the water contributed by the Tsidjiore Nouveand Bertol glaciers. Altogether, the pumping station atArolla catches and discharges 90 million m 3 of water.It is the most powerful pumping station in the schemeafter the one at Z’Mutt. Three double suction pumpseach with a capacity of 16.2 MW discharge their 4.2 m 3per second at a head of 312 m.12345678910111213141516Ferpècle headrace tunnel, discharge rate 8.4 m 3 /sec.Bertol Lower headrace tunnel, discharge rate 2.0 m 3 /sec.Siphon spillwayAfterbay reservoir drawoff tunnelAccess tunnelPumping station suction shaft and conduit, ø 1.80 mConduit crossing under torrentTsidjiore-Nouve buried headrace tunnel, ø 0.80 mBuried discharge conduit, ø 1.65 m to 1.90 m130 kV lineSwitchyardAccommodation and canteenAccess cableway to main collectorRoadsHeliportMaya afterbay reservoir1N25164550 50 100m143610715H814119121312345678910Pumping station suction shaft and conduit, ø 1.80 mLow pressure control valveMachine hallOverhead travelling cranePumpTransformerHigh pressure control valveCable gallerySwitchyardBuried discharge conduit, ø 1.65 m to 1.90 mCross-section of station2 units each comprising:1 pump delivering 4.2 m 3 /sec, head 312 m,and 1 synchromotor, 16.2 MW1 unit comprising:2 half-pumps each delivering 2.1 m 3 /sec,head 312 m, and 1 synchromotor, 16.2 MWTotal station discharge rate: 12.6 m 3 /sec.4 8 93 5 7101260 5 10m