CERN AC Note (2000-03)-General description of the CNGS Project

4. Civil engineering

4.1 General

All the CNGS project structures will be situated underground. Based on its experience in building the SPS, LEP and LHC accelerators, CERN is not merely taking all the precautions and measures required under the law but is also incorporating the lessons it has learned from undertaking previous projects. The aim of CERN will be to lessen significantly the impact of such a project on the surrounding environment.

4.2 Safety coordination

Design study and construction contracts are subject to international calls for tender. The conditions and limits to services provided, specifications and obligations of all kinds imposed on contractors of various types are very clearly defined. In particular, firms will be required to abide strictly by all regulations of the Host States, according to the area where the work is being done, as with the LHC at present.

In this spirit, CERN has a contract with a specialist consultant responsible for the health and safety coordination assignment on the CNGS site that meets the provisions of European Community directive 92/57/EEC of 24 June 1992 on the implementation of the health and safety requirements on construction sites.

Under the terms of its contract this firm will take part in the entire conceptual design study and development phases of the project. During the construction phase, it will be in charge of implementing the General Safety Plan.

4.3 Working hours

Working hours will conform to the relevant legislation. Work underground will generally be done in round-the-clock, five-day week shifts with possible Saturday overtime in exceptional cases to meet deadlines, safety or technical constraints.

Outside normal working hours, surface work will be kept to a minimum and applicable noise abatement legislation will be observed. Surface transport of spoil is forbidden during night-time hours.

4.4 Geological constraints

The work will be conducted entirely in the molasse of the Geneva Valley Basin. This rock is composed of many strata, typically about a metre or so thick, of variable quality ranging from relatively soft marls to very hard sandstones with intermediate elements grouped under the name sandstone marls, consisting of a soft rock that is more or less impervious to water that is scarcely ever fractured and is not very abrasive. However, it does have certain shortcomings due to its low mechanical strength and the changeable quality of the marls, sources of localized instability or swelling, and sometimes to the presence of liquid or gaseous hydrocarbons, particularly in the sandstones.

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