Nepal is very busy for Hydropower and more projects are coming," says Tara Nath Sapkota, managing director of contractor High Himalaya Hydro Construction Pvt. Ltd (3HC). "Our company is growing very fast and we are purchasing new equipment. Last year we spent 115 million Nepalese Rupees in equipment (> USD 1M) and still we will be purchasing more. As far as manpower is concerned we will be taking on more as well."
Among the purchases in 2015 was a Sandvik DD321-40 2 boom drill jumbo with telescopic boom, and the firm says it plans to buy another jumbo to meet the growing tunnelling demand. "One is not enough to serve the market and we want to grab the market opportunities. We will also buy more haggloaders and more batching plants as well," says Sapkota.
Despite the huge potential for hydropower in Nepal, estimated by the Nepal government-owned Hydroelectricity Investment & Development Company to be 83,000MW, installed capacity today is only 700MW. At the same time neighbouring states energy," says Sapkota explaining that political instability had previously held back development but that the adoption of Nepal’s new constitution in September 2015 means that the country can now move forward on its projects.
One such scheme is the Mistri Khola hydropower project in the Myagdi district, which will add 42MW of clean energy to Nepal’s system. Civil works will be carried out by 3HC for client Robust Energy Pvt. Ltd under a contract worth 1.4 billion Nepalese Rupee (USD 132M). "The geology of the Himalayas is very variable and very difficult. There is a lot of tectonic movement and faults. In many locations the rocks are not good, not hard or durable and it is very weak rock but this project Mistri Khola where we are working the rock is relatively good," says Sapkota.
That is not to say that there will not be challenges. The 2.3km headrace tunnel in particular is set to be the most difficult aspect of the works. "The geology of the headrace tunnel is not good, we might get some moving ground, we might get some shear zones and some water inflow. This might take some time to stabilise the rock so it is going to be challenging. We plan to have some umbrella grouting to make the rock more stable," says Sapkota.
Basic rock conditions throughout the project are gneiss and quartzite with schist, and as well as the head race tunnel 3HC will build the intake structure, weir, diversion tunnel, underground settling basin, access tunnel, surge shaft, valve chamber, anchor blocks, saddle support, power house, switch yard and tailrace tunnel. At peak there will be 500 men on the scheme. For tunnelling drill and blast will be used for the larger tunnels such as the headrace tunnel which, which is an inverted D shape with a cross sectional area of 14.3m2. For smaller sections such as the 44m inlet tunnel or the 60m tailrace, pneumatic jack hammers will be used.
Temporary support for the tunnel will consist of shotcrete and support bolting to hold the face for between 4 and 8 hours. Final lining for good to fair rock includes 100mm to 250mm thick steel fibre/mesh reinforced shotcrete with pattern rock bolting. For poor rock concrete lining with reinforcement will be used. The lining has been designed by Hydro-Consult Engineering. Sapkota estimates that the project will take 30 months to complete. "Thirty months is enough time but if there is difficulties in the tunnel and it takes more time to stabilise then it might take more time but otherwise 30 months is enough," he says.
Beyond the Mistri Khola scheme 3HC is working on a host of other smaller hydroelectric projects in the region. The 15MW Hewa Khola A project is in the completion stage; in Eastern Nepal another project of 6MW is at peak construction, "It is going full swing so it is very good," says Sapkota. The 7MW Mai Khola is now complete and the Medi Khola 3MW project is also under construction. "Soon we will be starting another 15MW project in the western part of Nepal, Rudi Khola."
These projects may be small compared to some of the larger projects underway in the Himalayas but they represent progress for Nepal. With potential for an enormous 83,000MW, and power a much needed development, the opportunities for contractors are vast, but so are the challenges. As Sapkota points out many of his employees have decades of experience of working in the unpredictable rock of the region.
"There is competition and some new firms entering the market, but experience counts. Our engineers have 35 to 40 years of experience," he says.
This experience will no doubt be tested if Nepal follows through with delivering its hydroelectric projects in the volatile and unpredictable rock of the Himalayas in the years ahead
