Seite - 614 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 6 Sediment particle size distribution Distribution de la granulométrie du sédiment 2.2. Client requirements On basis of the management plan of dam operation, and on the envi- ronmental constraints, A2A requested to fulfil following design criteria:  maximum water level variation to be considered inside the reservoir is 9 m, with a water level variation between 475 and 484 m a.m.s.l.; maxi- mum gradient of water level variation can reach 1 m/hour;  maximum concentration of sediment in the slurry discharged down- stream the dam cannot overcome 9 g/l for environmental reasons;  possible presence of wood debris and large stones on the sediment layer to be dredged has to be considered;  during dredging activity, the water intake feeding Somplago power plant is in operation discharging 66 m3/s (three Francis turbines), therefore turbidity generated by the dredging pump has to kept at the minimum;  during dredging activity, maximum allowed noise level at a distance from dredging pump of 300/400 m cannot overcome 45/50 dB;  dredging activity of 28,000 m3, including mob - demob activities has to be developed and completed in 100 natural days. 614