ISLAMABAD (APP) - Federal Minister for Water and Power, Raja Pervez Ashraf said that the construction of Tarbela 4th extension project of 960 MW had been given top priority and it would begin soon as the Wapda had already initiated work on it. Water and Power Development Authority (WAPDA) has already completed feasibility study as well as other required formalities to start the construction of the project, the Minister said. Tarbela 4th extension hydro project will add additional electricity of 960 MW in the national system to strengthen the economy and enhance hydro generation project, the Minister said. The total power potential of the project 2,100 MW originally which was enhanced to 3,478 MW and now it will be further enhancement to 4,438 MW with the completion of Tarbela 4th Extension Project, he said. The basic objective of the proposed project is to add more hydel power in the national system to strengthen the economy and enhance hydropower generation share, Raja Pervez Ashraf said. Giving details of the project, he said that the Project having capacity of 960 MW by two turbines of Rated Capacity 480 MW would be initiated on priority basis aimed at enhancing hydel power generation. The Project Tarbela 4th Extension will be built at Tarbela Dam which is situated on the Indus River at a distance of about 70 KM North West of Rawalpindi/Islamabad and about 50 KM upstream of Attock. It may be mentioned here that Tarbela Dam Project is the capstone of the Indus Basin Plan envisaged as replacement of water previously fed by eastern rivers. The project is considered backbone of the countrys economy and facilitates supply of irrigation water and production of power for industrial, agricultural and domestic uses. Civil works of Tarbela Dam was started in 1968 by the international contractors M/S TJV under design and supervision of M/S TAMS, was completed by 1974. The main Terbela dam project consists of 9,000 feet (2,743 meters) long, 470 feet (143 meters) high (above the river bed) earth and rock-fill embankment across the entire width of the river with two spillways cutting through the left bank and discharging into a side valley. Main spillway has a discharge capacity of 650,000 cusecs (18,406 cumecs), and auxiliary spillway 8,50,000 cusecs (24,070 cumecs). Two auxiliary embankment dams 2340 ft. (713 m) & 960 ft. (293 m) long respectively close the low level ridges in the left bank valley. A group of 4 tunnels, each about half a mile long through the right abutment rock, have been constructed for irrigation releases and power generation. Irrigation tunnel 5 situated on the left bank, for which NESPAK were the Project Consultants, was put into operation in April 1976. The reservoir is 60 miles (97 km) long, 100 square miles (260 square kilometers) in area and had initial gross storage capacity of 11.62 MAF (14.34 BCM) with a live storage capacity of 9.68 MAF (11.95 BCM).