Table 4: Samanalawewa Hydroelectric Project Main Characteristics Dam Type Rock Fill Earth Core Height 100m Length 530m Volume of fill 4.5Mm3 Reservoir Catchment Area 341.7Km2 Annual Average runoff 598Mm3 Normal High Water Level EL 460m High Flood Level EL 460.7m Minimum Operation Level EL 424m Live Storage Capacity 218Mm3 Spillway Type Gated overflow chute Design Discharge 3600m3/sec (10,000 year flood) Number of gates 03 Nos. Dimensions 12m wide, 14m high Spillway Ogee Level EL 446.7m Diversion Tunnels Number of Diversion Tunnels 02 Nos. Diameter 6.8m Length 550m Designed Capacity 145m3/sec (100 year flood) Low Level Outlets Emergency Release Gate 2.0m x 2.0m Jet Flow Gate Irrigation Release Gate 0.6m dia. Pipe with Howel Bunger Valve Head Race Tunnel Diameter 4.5m (concrete lined dia.) Length 5350m Surge Chamber Type Restricted Orifice Type Diameter of Riser 6.0m Diameter of Chamber 18.0m Height 94 m Penstock Type Steel Surface Diameter 3.85m to 2.85m Length 840m Power Station Type Surface Number of Units 02 Installed Capacity 120MW (2 x 60 MW) Average Annual Energy 403GWh Turbine Turbine Type Francis Turbine – Rated Head 320m Rated Discharge 42m3/sec Speed 500rpm Rated Output 62MW Generator Rated Output 71.6MVA Power factor 0.85 Generated Voltage 10.5kV Fly wheel effect (GD2) 715tm2 Tailrace Type Open Cannel Length 585m Power Transmission Transformers 02 Nos., 75 MVA, 3 phase Transmission Line 132kV double circuit 17km to Balangoda