The Wiental Sewer is part of a

large environmental project

that will increase considerably

the water quality of the rivers

around Vienna. After heavy

rainfall, the existing sewers of

the city reach their capacity

limits and the water, a mixture

of rainwater and wastewater,

overflows the sewerage sys-

tem and pollutes the rivers.

The new Wiental Sewer with a

diameter of 7.5 m and a

length of 2,690 m will not only

be able to drain rain and

wastewater, but also to store

110,000 m³ of it during rainfall

and discharge it afterwards in

a controlled manner into the

main wastewater treatment

plant of the town.

The Wiental Sewer will run

beneath the city of Vienna at a

depth of about 35 m and will

passes underneath the Wien

River as well as an under-

ground railway line at a dis-

tance of only 3 m. Along its

way, eight shafts with a depth

of up to 40 m each will be

installed.

The soil conditions in the area

consist of tertiary silts, sands

and clays. Over its whole

length, the tunnel will be

excavated below ground

water level which is up to 20

m above the future tunnel

crest.

For the excavation of the

sewer, a tunnel boring ma-

chine (TBM) with a diameter

of 8.60 m equipped with an

earth-pressure balance shield

will be employed. The TBM

has a jacking force of 6,400

tonnes and a driving power of

the cutter wheel of 2,000 kW.

Including its back-up system,

the TBM is 135 m long and

weighs 1,090 tonnes. The

tunnel will be lined with 1.50

m long concrete segments

and sealing gaskets. The

anticipated average driving

progress is 20 m per day.

The eight shafts along the

sewer which are up to 40 m

deep will be built by means of

diaphragm walls or secant

pile walls with pile diameters

of 2 m.

Wiental Sewer, Vienna, Austria

Contract Value:

USD (m) 67.5

Construction Period:

03/2004 – 03/2006

Client:

Magistrat der Stadt Wien (Vienna City Council)

Services:

Construction of a main sewer with an excavated diameter of 8.60 m

Reg

. 14-

bb-1

00-b

b-0-

020-

00