Experts Identify Causes behind NJHPP Tunnel Collapse

A Panel of Experts (PoEs) in their interim report has identified eight causes of the collapse of 969-MW Neelum Jhelum Hydropower Project (NJHPP) tunnel.

This was revealed by the Chief Executive Officer (CEPO), NJHPP, Muhammad Arfan, while briefing Senate Standing Committee on Power headed by Senator Saifullah Abro.

The CEO apprised the Committee in detail that it is a government scheme project, which was started in 2008 and completed in 2018. The PC-l was prepared in 1998 and approved in 2002. The length of the underground tunnel is 48 km from C1 to C3. He then briefed the Committee in detail about the tunnelling system and rock overburden of the project. The whole tunnel of 48km was underground. The PC-I of Rs. 84 billion was approved in 2002 and revised in 2017 with the cost of Rs. 506 billion. The tendering process started in 2017. Responding to the query of the Chairman Committee, the CEO NJHPP noted that three companies participated in tendering process. The Committee recommended CEO NJHPP to submit the bidding documents and process of Neelum Jhelum Project to the Committee. The Chairman Committee asked whether PC-I was updated in 2002 because it was prepared in 1998. The CEO NJHPP informed that it was not updated when it was approved in 2002.

Tauseef H Farooqi, Chairman, Nepra also stated that Neelum-Jhelum power station was closed due to major cracks in its tailrace tunnel at the end of July, 2022. The closure of the project was costing Rs 10 billion extra per month to power consumers as the restoration work on the project will be completed by June next year.

He added that if the tail race tunnel is renovated on short create, the work will be completed earlier but there was no guarantee that it will not collapse again and if the tunnel remains closed for a year, the consumers will suffer a loss of Rs 120 billion.

Regarding the incident of blockage inside Tail Race Tunnel (TRT), the Committee was briefed in detail about the layout of power house complex. It was informed that there was excessive water leakage in powerhouse and it was managed by dewatering pumps on July 4, 2022. On July 5, 2022, the pressure in the tailrace tunnel increased to 616m against normal pressure of 600m. The load decreased gradually from 969-200MW and pressure in the tailrace tunnel reduced to 601m. On July 06, 2022, the load further reduced to 125-MW and at 1300-hrs powerhouse completely shut down.

The CEO NJHFP further briefed in detail about the progress in tail race tunnel. The A7 was the only access point in the tunnel. The dewatering pump system is also under the tunnel.

Senator Muhammad Asad Ali Khan Junejo asked about the composition of soil in the tunnel. The CEO NJHPP informed that it has a complex geology comprising of inter-bedded sandstones, siltstones, sandstones and mudstones. The Chairman Nepra added that tail part was made up of short concrete and it appeared that later, a part of the tunnel was less strong or vulnerable as compared to the front part of the tunnel.

The CEO NJHPP further briefed that a team of Independent Panel of Experts (IPOE) was hired on the directions of Prime Minister of Pakistan. They have identified eight causes of tunnel collapse and submitted their first interim report. The Committee recommended to CEO NJHPP to submit the first interim report to the Committee. The Chairman Committee asked about the cost required for the rehabilitation of the project. The CEO informed that the cost required for rehabilitation is Rs. 2.7 billion.

The CEO NJHPP further informed that water in tunnel was used for the whole year but the months (Nov – Feb) are easy to stop the water and review the inspection for the rest of the tunnel. Senator Muhammad Asad Ali Khan Junejo suggested that remaining inspection of 40-km of tunnel was needed to be reviewed and priority must be given for reviewing as there are variations in the soil from C1 to C3 tunnel.

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