The project consists in the construction of a 24 km long headrace tunnel and 10 km of adduction pipes in order to exploit the Litani and Awali rivers for public drinking water supply. The water is drawn from a hydro power plant located in Joun, about 30 km from South Beirut, and conveyed to the Hadath and Hazmieh tanks, under design on the city uplands. The water supply system is calculated to support future growing flow rates starting from 3 up to 9 m³/s and includes: - 3 tunnels of about 24 km length and 2.8 m of diameter, excavated by 2 TBMs, and with a double ring of shotcrete and concrete coated with inserted PVC waterproof membrane; - 2 ventilation shafts, near the Damour syphon and a piezometric tank at the North portal of Khalde; - 1 syphon, which leads to a difference of 140 m in elevation and allows the underground crossing of the Damour river. The connecting branches are excavated into the rocks with conventional method and crossing in open air in the fluvial deposits; - 2 buried pipes, 10 km long and 1’400 mm of diameter each, both designed for pressures up to 25 bar; - 1 SCADA system for the plant control, which commands the numerous valves of controlling and interception. The watertight tunnel is designed taking into account low overburden and high pressure.