Bauer Engineering India Pvt. Ltd. is building a cutoff wall as part of construction of the 900 MW Arun III hydroelectric project on the Arun River in Nepal.
The river flows from Tibet through the Himalayas into China. Of all Nepalese river basins, it has the largest area covered in snow and ice.
Arun III, in the Sunkhuwashabha District in eastern Nepal, is a peaking run-of-river project. The dam will be 70 m tall and the headrace tunnel will be 11.7 km long. The underground powerhouse will contain four 225 MW vertical Francis turbine-generator units. Electricity from the project will be exported to India via a 217-km-long 400-kV double circuit transmission line. The foundation stone for the project was laid in May 2018.
Indian company Jaiprakash Associates Limited hired Bauer Engineering India, a subsidiary of Bauer Spezialtiefbau GmbH, to construct a cutoff wall to achieve a seal and reduce seepage water below the upstream cofferdam and in the left and right abutments.
Bauer’s scope of service includes completing 3,500 running meters of drilling and injection work on the cofferdam. A KLEMM KR 909 is being used for the drilling and injection work.
In the granular construction soil — composed of sand, gravel, rubble and boulders — the pore injections are executed by means of tube-à-manchette (a method that involves the use of perforated pipe along with a special sleeve grout) and annular grouting.
“Using the pore injections, we are able to fill the pores in the very loose soil with cement slurry and thereby reduce its permeability,” said Project Manager Satish Kumar. Bauer also will carry out rock grouting to fill gaps, fractures and cavities in the rock.
Challenges to the project include the remote location in the Himalayas, the construction soil, logistics and a tight schedule, with snow starting to melt in March, causing the water level in the river to rise and making work more difficult.
Bauer started the work in December 2021 and expects to complete it by May.
In February, SJVN Arun-3 Power Development Company, a unit of SJVN Limited, signed term loan documents for an INR6,334,000,000 ($84.85 million) loan to further construction of the Arun 3 project.
