Fault at Neelum-Jhelum tunnel rectified

969-MW hydropower project starts generating electricity again after a year

ISLAMABAD:

The 969-megawatt Neelum-Jhelum Hydropower Project (NJHP) has started generating electricity again after a gap of one year following the completion of the restoration work in its tail race tunnel.

Federal Water Resources Minister Khursheed Ahmed Shah visited the power project to inaugurate its electricity generation afresh.

According to a report, a fault had developed in the Neelum-Jhelum plant on July 4, 2022, leaving the powerhouse dysfunctional. The project was commissioned in 2018 and had since been working satisfactorily with power generation of 18.28 billion units.

However, on July 4, when the plant was running at its full capacity (969MW), an abnormal increase in water leakage was observed which was controlled through continuous drainage pumps and an investigation into the excessive leakage was started.

On July 5, an emergency meeting was held between the project management and the project consultants team to analyse the situation and determine the root cause of excessive water leakage.

It was observed that tailrace tunnel (TRT) had obtained an abnormal pressure of 616m instead of the normal 600m. It was also pointed out by the project consultants that abnormal pressure of 616m in the TRT had been recorded which otherwise remained below 600 meter.

Accordingly, to ascertain behaviour of TRT, one unit was shut down which resulted in decrease in pressure to 608m. The consultants recommended that the TRT pressure should be below 604m. In this way, load was reduced gradually.

On July 6, it was determined that the abnormal increase in pressure and water leakages/seepage was due to blockage in TRT and considering the safety of the structure and all other equipment, the power house was shut down on July 6.

Soon afterwards and after necessary preparation (lowering of bulkhead gates by Mobile Crane, functional check of dewatering pumps etc.), dewatering was started on July 10. After completion of dewatering up to the main collapse point (293m), an inspection of the tunnel was carried out.

“It was found that tunnel is fully blocked in 42m portion (between 251m and 293m) besides other damages,” the report said.

Immediately after the incident, M/s China Gezhouba Group Company (CGGC), the contractor for construction of civil works, was engaged for carrying out repairs. The contractor started mobilisation at the site and subsequently a contract agreement was signed with the firm on Aug 25. Work on the restoration of plant is going on day and night, the report added.

According to the report, 17 consulting firms were contacted. Since the task to ascertain the causes of the fault was urgently needed almost all the firms expressed their unwillingness for undertaking the services on such a short notice.

The ministerial committee was requested to engage the Independent Panel of Experts (IPoEs) instead of engaging the consulting firms, which was accordingly approved by the inter-ministerial committee on Aug 25.

The NJHP is a run-of-the-river hydropower project that started electricity generation in April 2018. It envisages the diversion of Neelum River through a system of tunnels out-falling into Jhelum River.