Mott MacDonald has been appointed lead consultant for the 1,410-MW Tarbela 5th Extension hydropower project in Pakistan.
The project, being delivered by the Water and Power Development Authority of Pakistan, will increase the Tarbela Power Plant’s total generating capacity from 4,888 MW to 6,300 MW. The aim of the extension is to increase seasonal power supply in Pakistan to meet increasing demand for electricity.
Mott MacDonald was also lead consultant for the 1,410-MW Tarbela 4 project, which was commissioned in October 2018.
The Tarbela power station, situated below what Mott MacDonald says is the largest earthfill dam in the world, has been steadily developed on the Indus River since it was originally commissioned in 1976. The dam was designed to store water for irrigation, flood control and the generation of hydroelectric power. It is 148 meters high and 3,000 meters long, with two gated spillways and five tunnels that provide irrigation releases and power generation.
The project incorporates a new 1,410-MW hydropower plant to be constructed at the end of an existing 43-year-old tunnel through Tarbela Dam. The project also includes a new 50-km-long 500-kV transmission line and a 20-MW to 40-MW floating solar pilot project, which will be the first in Pakistan, Mott MacDonald says.
Mott MacDonald conducted the feasibility, scoping studies and detailed design for the 5th Extension project of Tarbela. Unlike the other four tunnels, the fifth tunnel is situated within the left abutment of the dam. Using the tunnel for dual purposes, such as irrigation releases and power generation, has presented a unique set of challenges. Many of the challenges relate to its location between two large spillways, their associated plunge pools and a common discharge channel.