ISLAMABAD: Prime Minister, Shehbaz Sharif has sought comprehensive report on collapse of Head Race Tunnel of 969 MW Neelum-Jhelum Hydropower Project (NJHPP), shut since July 2022, inflicting billions of rupees’ financial loss to the national exchequer.
Well informed sources told Business Recorder that while presiding over a meeting on power load shedding the prime minister also sought reasons for the delay in repair/ rehabilitation work of Tunnel and directed Chairman Wapda Lt Gen Sajjad Ghani to submit updated report on it to him.
The sources said, repair of tunnel will be further delayed as more damage is reported than earlier estimates of experts.
Experts identify causes behind NJHPP tunnel collapse
The experts have cited following reasons for exceeding timelines: (i) increased in quantities;(ii) risk of further collapse/ safety of the tunnel;(iii) change in design and methodology for repair;(iv) limited access (only from downstream side);(v) shortage of spares, tools, material and machinery (import issues); and (vi) repatriation of forex.
International Panel of Expert (IPoE) has analysed eleven different root causes/ possibilities causing the blockage. They have opined that not a single postulated root cause would be sufficient to cause a tunnel collapse of the magnitude of the one observed in Tailrace Tunnel.
Two interim reports have been submitted by IPoE and final report received on February 24, 2023 is under discussion with IPoE.
Project consultant’s point of view on the root cause discloses that the engineer generally agrees with the IPoE analysis which would vary with respect to some assigned probabilities and definitions. Collapse of tunnel lining distress appears mostly associated with the mudstones.
Engineer’s opinion is that mudstone degradation appears to be a major factor, in combination with others, affecting many areas of the tunnel.
The sources said, documents for hiring of services of international experts for inspection of Head Race Tunnel via Remotely Operated Vehicle (RoV)/AUV on International Competitive Bidding (ICB) has been prepared.
According to sources, ICB process will take 4-5 months followed by mobilization and execution. However, urgency of the work demands using alternate method as per PPRA rule-42.
Of-late, Senate Standing Committee/ GoP also asked NJHPC/ WAPDA to carry out the inspection of shotcreted Headrace Tunnel to ascertain the integrity of the structure and avoid any risk for project closure in future.
Out of 48 km, 20 km is in shotcrete lining in the Headrace Tunnel. At present the tunnel is full of water and tailrace tunnel is blocked, so dewatering is not possible.
Copyright Business Recorder, 2023