PDF - 9Mo - Grande Dixence SA

GD. P.52Fionnaypower plant800 metres with a 73% gradient!To bring the water from the Grande Dixence dam tothe first turbines at the Fionnay power plant, a ninekilometerunderground tunnel had to be built and fittedout. This pressure tunnel slopes steeply: the averagegradient is about 10%. When it was driven through,the labourers and engineers were faced with seriousproblems due in particular to water seepage.Completely underground, the Fionnay plant has 6generating units, each equipped with 2 Pelton turbines,total capacity 320 MW. The head varies between 680 mand 874 m, depending on the level of water in theGrande Dixence dam.The surge tank is at the end of the Louvie tunnel, inBagnes valley; the tunnel then becomes a steel-linedshaft which plunges more than 800 m down a 73% incline!The shaft ends at the Fionnay power plant distributor,an enormous cavern hewn out of the rock.Fionnay Village