ISLAMABAD: The Water and Power Development Authority (Wapda) is reportedly repairing cracks in trash racks of Tunnels 3 and 4 of Tarbela 4th Extension that appeared in second time in two years, well-informed sources told Business Recorder.

Member (Power) Wapda, Jamil Akhtar in a letter to Secretary Ministry of Water Resources has noted that under Tarbela 4th extension project, the intakes of tunnel 3 (unit11-14) and tunnel 4 (units 15-17) were raised. The raised intakes were operated for the first time in 2021. During inspection in February 2022, cracks were observed in the bottom two rows of trash racks of both intakes. After repair of the damages in trash racks, units (11-17) were operated during peak season of 2022. It was decided that inspection of trash racks will again be carried out before full load operation of units in 2023.

During inspection through foreign divers from December 11-18, 2022, cracks have again appeared in trash racks and majority of the cracks are in the bottom row of all bays of Tunnel No. 3 & 4.

According to Wapda, for the safety of the structure and generating units, it is essential that the trash racks may be repaired before high flow season. The required repairs will be carried out through divers after lifting the trash racks through barge. The said repair works require 40 days with a contingency of 10 days (total 50 days). The divers and barge are presently engaged at Tunnel No.5 under Tarbela 5th Ext Project, after which they will be available for said repair works.

For the repair of task racks, shutdown on Tunnel 3(units 11-14; 1728 MW) and Tunnel 4 (units 15-17; 1410 MW) will be required daily from 0800-1800 Hrs. During this time, both tunnels will not operate. After 1800 Hrs, one tunnel will be made available for operation of generating units while the other will remain shut. After completion of work on one tunnel, the repairs of trash racks of other tunnel will be carried out by adopting same procedure.

In view of planned repair work, tunnel 3 is shut down till March 1, 2023 whereas tunnel 4 will remain closed from 0800-1800 Hrs daily till March 1, 2023. In the next phase, Tunnel 4 will be shut down from March 2-22, 2023 while tunnel 3 will be closed from 0800-1800 Hrs daily. Contingency period will comprise of 10 days.

In 2021, Transparency International-Pakistan (TI-P) had demanded investigation against the former Chairman Wapda in the light of report prepared by Prime Minister Inspection Commission, which stated that decision of “premature” inauguration was taken at the level of Chairman Wapda without consultation of Member (Power), Advisor on project, Chief Engineer (O&M) and Project Officer which resulted in financial loss of $ 753.7 million.

According to sources, repair work will not have any impact on water outflows and power generation.

Copyright Business Recorder, 2023

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