MIRPUR (AJK) - Total generation capacity of the Tarbela Hydropower Station would rise to 4828 megawatt (MW) after the installation of 1350 MW units as part of 4th Extension Project, official sources said. This was stated by Pakistan Water and Power Development Authority (Wapda) Chairman Shakil Durrani during his visit to the project. Tarbela Dam Project General Manager, Project Director and other officers concerned were also present during the visit, the sources told The Nation here on Monday. Terming it a significant development, the Chairman said that the consultants, engaged for preparation of detailed engineering design, tender documents and project cost (PC)-I, have established in their findings that three turbines of 450-MW each could be installed instead of two turbines of 480-MW each, as envisaged in a study conducted earlier in 90s. He said that the independent panel of international experts has also endorsed these findings. This is a good omen in view of the increasing requirements of electricity in the country, he added. Earlier, the Chairman visited Tunnel No 4 and proposed site of the powerhouse for Tarbela 4th Extension Project. He also visited Tarbela Power House to witness Unit No 4 that has recently been rehabilitated by WAPDA with financial assistance of the United States Agency for International Development (USAID). He appreciated the officials concerned for completing the rehabilitation work well before the target set for the purpose. It is pertinent to mention that Tarbela 4th Extension Hydropower Project is a part of least-cost energy generation plan, being implemented by the Wapda on priority to harness indigenous hydropower resources of the country with a view to improving the ratio of hydel electricity in the National Grid. Most importantly, the project will also provide a cushion to undertake rehabilitation and up-gradation of the existing Tarbela Power House during the lean period. The work on detailed engineering design, preparation of tender documents and PC-1 of Tarbela 4th Extension Hydropower Project, undertaken by WAPDA on fast-track basis, is expected to be completed by September 2011. Afterwards, this mega project will be available for initiating construction work, completion of which has been planned in a short-span of four years. It is important to note that hydel is the cheapest source of electricity with an average cost of Rs.1.05 per unit.