Dewatering, waterproofing and drainage - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 190

For the construction of the Euerwang Tunnel on the new line from Nuremberg-Ingolstadt
for the Deutsche Bahn AG, the tenders from the company are based on an estimation
quantity of water ingress according to DIN 18 312, that is measured about 50 m behind
the face, with the following water quantity limits being defined:
- short-term water ingress up to 4 hours:

100 l/s

- long-term water ingress over 4 hours:
a) in the top heading: 10 l/s
b) in the bench and invert: 20 l/s
SIA standard 198. The Swiss SIA standard 198 (issue 2007) [218] states the following
under clause 19.2 “Obstruction resulting from water for tunnelling in rock” about the
drainage, payment and measurement of incidental water during tunnelling in hard rock:
19.2.1 Tender
19.2.1.1 The crew daywork rates deducted from the bill of quantities for obstruction re-
sulting from water are to be taken into account proportionately in the construc-
tion schedule.

19.2.1.2 The number of planned and payment programme days for obstruction result-
ing from water is determined with consideration of reduction factors on crew
daywork rates.
19.2.1.3 The reduction factors on crew daywork rates for the determination of the
planned and payment construction time are to be laid down on each project
according to the hydrological conditions. If this is not specified in the tender
documents, the values in Table 17 are considered contractually agreed.

19.2.1.4 Water measurement in caverns and shafts is to be regulated for each project in
the tender documents.

19.2.2 Payment regulations and remeasurement provisions

19.2.2.1 Water ingress results in reduced work performance (working in water or extra
costs for drilling and repairs to construction site facilities). This reduced perfor-
mance (obstruction) is paid according to crew daywork rates.
19.2.2.2 Payment for obstruction is dependent on the tunnel gradient (rising or falling),
the excavation cross-section and the water quantity less service water, which
occurs at the face during a period of at least eight hours in the relevant section.
19.2.2.3 Obstruction due to water quantities, which do not reach the lower figures given
in Table 17, are included in the excavation prices.
19.2.2.4 The water ingress will be measured by the employer and the contractor with
suitable instruments and at an appropriate location. Measurement instrumenta-
tion is to be regularly maintained and sporadically calibrated.
19.2.2.5 The relevant section behind the face for the determination of water ingress is
100 metres.
19.2.2.6 In case of immediately consecutive partial excavations, the face that is furthest
back counts as the face.