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Civil Engineering LHC Project |
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Civil Engineering LHC Project |
Scope
Construction - Photo
Management
Environment and Safety
Difficulties
Almost all of the existing LEP surface and underground infrastructure as much as possible will be re-used for the civil engineering of the LHC in order to minimise the cost of additional infrastructure.
The main new basic facilities will thus be at the two sites of the ATLAS and CMS detectors at Points 1 and 5 respectively. Large underground halls will be excavated at these points to house them , as will a set of annexed chambers and access tunnels. The ALICE and LHC-b detectors will be installed at Points 2 and 8, requiring only minor modifications to the existing structures.
Additional structures which are essential for the operation of the new cryogenic machine will also be distributed around the ring. This will particularly concern the injection tunnels between the SPS and LHC (formerly LEP) machines, underground beam-stop structures and buildings to power the cryogenic installations.
One of these structures, the transfer tunnel between SPS Point 4 and LEP Point 8 (TI 8), will be dealt with separately, as it is being jointly financed by Switzerland and the canton of Geneva.
All the facilities to be built are shown on two diagrams, one for the underground and the other for the surface structures. These diagrams provide access to the updated photographs of the various work sites.
The civil engineering project, estimated at some 350 MCHF, has been divided up geographically according to its characteristics into four packages.
- Package 1 Underground and surface structures on the site of the ATLAS experiment. - Package 2 Ditto for the CMS experiment. - Package 3a All the LHC structures except those of Packages 1, 2 and TI 8. - Package 3b Injection tunnel TI 8.
In view of the management structure adopted, the ST-CE Group has had to adapt its organization to the special nature of the project. It was therefore faced with the difficult task of selecting, with the SPL Division, three groups of consultants and four groups of contractors. In view of the current competitive situation in this field throughout Europe and the resultant risks of unrealistic bidding, it has tried to establish an easily viewed, effective and indisputable procedure.
This has led to the adoption of the idea of calls for tenders involving two "envelopes", one technical and one commercial. The opening of the latter has been made subject to the establishment by a jury of experts of the full compliance of the former with the specifications. The contracts for them were signed between March and October 1998 so that they can be updated as closely as possible to the development of the project and the technical solutions finally adopted.
Package 1 was subject to a "Building Permit", issued by the canton of Geneva in January 1998. It was possible to start the work on 30.3.98.
Starts on the work site installations for the other packages had to await for the issue of the "Déclaration d'Utilité Publique" (DUP) by the French authorities which came on 30.7.98 (Déclaration du 6 Août 1998). The official dates for the start of work were:
- Package 2 31 Août 98 - Package 3a 13 Juillet 1998 - Package 3a 15 Novembre 1998
The architects who have contributed to the aesthetic design and functional layout of the project are Hervé DESSIMOZ for the Swiss side and Robert PAUCOD for the French side.
Special care was taken to blend the structures into their environment, as witness all the measures taken by the "Impact Study" covering both the construction and operating periods.
The French building permits or their equivalents have been issued or are being obtained or prepared in accordance with the schedule for the start of work at each point.
Finally, the Civil Engineering Group will attach particular importance to the observance of the safety standards in accordance with the European directive dated 24.6.92, which increases the responsibility of employers. A highly comprehensive organisation has thus been set up in accordance with the French laws and decrees in force designed to take all possible steps to prevent the risks inherent in this type of project. Effective support has been obtained through two safety and health protection co-ordination contracts awarded to specialised firms:
- AIF (France) for the design phase;
the COSSEC (F) - WATERMAN (GB) consortium for the construction phase.
The main difficulties or challenges facing the operative teams in the performance of the work are:
- the excavation of huge underground halls in the mixed nature of the molasse of the Leman basin;
- the 55 metre passage through water-bearing moraines during the excavation of the two access shafts to the underground halls for the CMS detector;
- the performance of work closely involved with the existing LEP structures with the absolute requirement not to interfere with LEP's operation until its final shutdown in October 2000, in accordance with the project schedule.
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Scope