Special Construction
Himal Hydro is accustomed to difficult site conditions. We have adapted equipment and process to solve difficult logistics problems thereby enabling the timely completion of projects in remote, high altitude sites.
Himal Hydro undertook the construction of lined chanal with a gate structure for controlled discharge of water to lower the water level of Tsho Rolpa glacier lake (Altitude: 15,000ft/4,600m above MSL, site reached: after 7 days of trek) to reduce the risk of GLOF (glacier lake out brust flood).
Pipe Roofing with Boomers and Tubex 76 (Fore poling)
Due to extremely poor ground conditions(land slide mass) for excavation of penstock tunnel in the Middle Marsyangdi Hydroelectric Project, some form of additional ground treatment system also known as Pipe canopy or Umbrella Method was required to allow NATM tunneling to progress. This method was used for first time in Nepal and it was very successful. A total of 15 holes were drilled in the crown of the tunnel at 0.5 m centers. Length of installed threaded casing was 12.5 m of 89 mm diameter having 4.5mm wall thickness. The length of each casing were 315mm,1285mm and 1895 mm respectively as this would allow easier handling for Tubex inside the tunnel. A false portal was built at the tunnel entrance, and the spacing of the steel arches was continued at 1.5 m whilst under the Tubex umbrella. Atlas Copco H282 Boomer along with Sandvik tubex 76 drilling accessories were used for drilling operation.
A total of 90 m long horse-shoe shaped, cross section area 40sqm tunnel was constructed using this method and was completed ahead of schedule.
