Project to propose accelerating measures during EJG meeting

Hydropower: To speed up work, the Punatsangchu Hydroelectric Project Authority II  (PHPA), which is already more than six months behind schedule, will propose accelerating measures to the empowered joint group in its upcoming meeting next month.

This is to catch up on time, specifically on the dam construction.

The project came short of a disaster, that its sibling 15kms upstream the PHPA I faced in July 2013, when its left bank of the project site almost slid because of poor geology in February this year.

PHPA II managing director RN Khazanchi said that the PHPA I right bank slide gave them enough lessons and experience to deal with the situation on time.

“We’re lucky we’d that experience of working in bad geology of dam abutment, this time as soon as the bank gave problem, we took immediate remedial measures,” he said.

A total of 250 deep cable anchors of various lengths were used at four different levels.  While the project is cable anchoring at another level, some more cables would be inserted at another two levels further down.

These anchors replace the normal 20m long rock bolts to support lose mass and prevent it from sliding. Normally, with the bolts, concrete is laid on the surface to prevent slides.

“That has given us some set backs mainly in terms of time and for that reason we have proposed some acceleration measures to the authority,” RN Khazanchi said.

“This is the most critical issue for the project right now and we have submitted it as one of agendas for the meeting.”

If the empowered joint group approves the measures, a committee will look into the details, which could take a little more time. However, the dam construction is expected complete by March 2018.

The cost of the remedial measures would be met from the contingency fund of the project.

The management also proposed to hire a blasting expert on long-term contract to monitor the controlled blasting at the site.

The poor geology was not reflected in the project’s earlier investigations. The managing director said drilling investigation cannot be done for the whole area, and that those selected spots where the company drilled did not shown any signs of poor geology.

“It’s only when we actually began excavating deeper, that we realised the problem,” RN Khazanchi said.

The prime minister during his visit to the site in March this year had asked the management to complete the project by March 2018.  Lyonchoen also installed the sa-chu-bum-ter to signal the laying of the dam foundation in April this year.

“Only with the acceleration measures we can meet that deadline or else it’ll be delayed by another six months,” RN Khazanchi said.

“If we can complete the dam in March 2016 with the accelerating measures, we can plug the water diversion tunnels two months before March as the river is smaller,” he said.

Once the dam is complete, testing the whole system including the filling of the dam and tunnels, usually takes three months.

If the acceleration measures are not approved, commissioning of the project could extend towards the end of 2018.

Construction of upstream cofferdam began following the diversion of Punatsangchhu in May 2013. The 1,020MW project was started in December 2010 and is expected to generate 4,357 million units of electricity on an average every year.

By Tshering Palden