PDF - 9Mo - Grande Dixence SA

GD. P.35Z’Muttpumping stationBeauty spotAt the bottom of the Mattertal valley, clinging to the lastAlpine pastures, a few elegant ‘mayens’ are evidenceof the hamlet of Z’Mutt. In this beautiful and peacefulspot, the Grande Dixence engineers were determinedto show respect for nature and harmony. As far as possible,the concrete invasion was kept within limits. Theonly major visible section is the dam that blocks thegorge. Yet, despite its height of 74 metres, the slim andelegant arch dam blends discreetly into the landscape.Apart from the service building, all other facilities (sandand gravel traps and pumping station) are belowground.Here in this wild enchanting place, water is gatheredfrom the Bis and Schali glaciers that overhang the Viègeand from the Gorner. Some experience was neededbefore the Gorner was brought under control. Everysummer in fact, the sudden emptying of a glacial pocketthreatens to submerge everything.4 pumps with a total capacity of 88 MW are used atZ’Mutt to deliver 140 million m 3 of water each season.They are driven through a penstock, an inclined steellinedshaft that brings the water from 1900 metresaltitude to the Trift tunnel at 2400 metres altitude or thelevel of the main water conduit.7N64221 Arch dam, height 74 m852345Afterbay reservoir, useful volume 700,000 m 3Water intake and headrace tunnel, ø 2.30 mDischarge shaft to main water conduit, ø 1.80 to 1.90 mSchali-Bis steel-lined shaft, ø 1,35 m142 3 1215119 1619917180 50 100m2112H13 2011106 Bodmen underground afterbay reservoir, useful volume 2500 m 37 Schali-Bis headrace tunnel, discharge rate 8.5 m 3 /sec.8 Bodmen spillway tunnel9 Gornera headrace tunnel, discharge rate 25 m 3 /sec.10 Service and control building11 Operating cableway12 Access gallery to power plant13 Drainage tunnel14 Dam access tunnel15 Emptying of afterbay reservoir and return to Z’Mutt stream16 Cable gallery17 Switchyard18 130 kV line19 Roads and road tunnel20 Z’Mutt-Schönbühl path21 Heliport22 To 12 MW plant in Mutt (EWZ)Cross-section of station2 units each comprising:1 pump delivering 5.5 m 3 /sec., head 470 m, and1 synchromotor, 30 MW2 units each comprising:1 pump delivering 3.2 m 3 /sec., head 65 m, and 1 synchromotor,14 MWTotal pumping station discharge rate: 17.4 m 3 /sec.123456789Low pressure control valveInternal servicesTransformerCable galleryOverhead travelling craneMachine hallMotorPumpHigh pressure control valve4536278910 5 10m