1995-2003 “Complex of Hydraulic Structures for Diversion of the Vorotan River Runoff to the Basin of the Arpa River”

Hydraulic system of discharging Vorotan river runoff to the basin of Arpa river.

The hydraulic work comprises the following main objects:

1. 21.6 km long tunnel with 8.9 m2 section,
2. 4 shafts of 50-300m depth,
3. 2 approaching adits,
4. Headworks: the intake, water seals;
5. Spillway section at the exit gate.

The construction was commenced in 1982, but due to financial shortages the works on main structures were stopped in1993 and up to 1998 the works on pumping were performed to keep up the underground openings in working condition.
By the end of works the construction of tunnel has been carried out under highly complicated hydro geological and mining engineering conditions with frequent outbursts of rock mass on the stretch of about 800 m length in weakly waterlogged rocks, as a result of which special drifting methods was used to form a screen of pipes along the outline of underground opening, injection of grout behind an auxiliary reinforced concrete lining.