JSC Nenskra Hydro, the Nenskra Hydropower Plant (HPP) project company will use the latest technology for excavation of Nenskra HPP tunnels, namely, the two Double Shield TBMs (Tunnel Boring Machines), custom made especially for JSC Nenskra Hydro by the German company Herrenknecht, will be used.
The length of the machines is 190 and 250 meters, and the diameter is respectively 4.3 m and 5.3 m. Both machines have already been transported to Georgia and the equipment is currently stored in Poti.
Nenskra HPP infrastructure will include two tunnels. The Nakra transfer tunnel connects Nakra valley with Nenskra valley and is approximately 12.5 km long with 3.5 m diameter, it will divert water from the Nakra weir and into the Nenskra reservoir. The Nenskra headrace tunnel follows the left bank of the Nenskra valley and is approximately 15.1 km long with 4.5 m diameter. The tunnel will connect the reservoir with of the powerhouse.
“The use of TBM has several advantages, first of all, safety and reduction of environmental impact. The TBMs we have purchased for the project combine tunnel excavation with concrete segment lining, which guarantees the safety of the workers, as well as the safety and efficiency of the tunnels’ operation in the future”, said Teimuraz Kopadze, Chief Operations Officer of JSC “Nenskra Hydro”.
Excavation of tunnels is planned from 2020. Prior to that, preparatory works are being carried out in Chuberi and Nakra villages of Mestia municipality, which includes construction and rehabilitation of bridges and roads, as well as construction of temporary camps and power supply lines.