Sochi Sea Outfall
Russia, Sochi
2012 – 2013
Record tunnelling at the Black Sea

A modern sewage treatment plant is being constructed in the Sochi district of Bzugu, so that the city is well prepared for the Winter Olympics 2014. The plant is part of an initiative by the local administration and Moscow's government, which aims to comprehensively increase the capacity of the entire local sewage system. The project will also lead to sustainable protection of the environment. A piping system conducts the sewage treated at the plant into the Black Sea so far away from the coast that residents and the environment are not affected.

The connection from the Bzugu sewage treatment plant to the coast and from the coast out to the Black Sea was drilled using an AVN2000AH made by Herrenknecht. A navigation system from the company VMT GmbH of the Herrenknecht Group took over the precise navigation. The machine started excavating the sea outfall in a 25 meter deep shaft in February 2012. Tunnelling operations along a length of 1,411 meters were completed in August 2012. High abrasiveness of the mainly encountered limestone meant extreme demands on the excavation tools and the pumps of the slurry circuit. The machine mastered this challenge without any problems, achieving top performances of up to 30 meters per day. The tunnel builders stopped the machine at the target point on August 28, 2012 beneath the seabed around 800 meters away from the coast.

Herrenknecht equipped the machine with a "rescue module" to ensure safe recovery. This additional equipment allows the machine to be sealed at the bottom of the sea by means of a bulkhead and separates it from the tunnel using cylinders and the necessary hydraulic supply. The machine can then be lifted by a crane or with balloons to the sea surface.

After recovery of the machine in October, the AVN was completely refurbished and employed in a second project. The plan is to connect a new sewage treatment plant in the Adler district of Sochi with the sea through a sea outfall. From mid-December 2012 to the end of March 2013 – within 100 days – the AVN2000AH installed a total of 2,014 meters of pipeline with top performances of up to 37 meters per day. In the DN 2000 (2.5m) diameter range, this constitutes a world record achieved by the Russian tunnel constructors.

The large-scale infrastructure package in Sochi includes the construction of new road and railway connections. An EPB Shield (Ø 10,630mm) and a Single Shield TBM (Ø 13,210mm) from Herrenknecht excavated a road tunnel (3.1km) and a railway tunnel (2.8km) in the years 2010 to 2012.

Data Sheet

Country, Location

Russia, Sochi


2012 – 2013




Heterogeneous ground
Limestone, clay

Tunnelling length

3,425 m

Machine Data

1x AVN Machine:
Diameter: 2,525 mm
Lining method: Pipe jacking
Cutterhead power: 315 kW
Torque: 780 kNm

Your contact person Contact us

Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.