The Consultants have, as required, developed preliminary requirements for an air traffic control system, definitions of airspace reserves, typical procedurcs for operation within the terminal area, typical Standard Instrument Departures, Standard Terminal arrival Routes and Instrument Approach Procedures. They have also indicated the areas on Lantau island and the mainland where structural heights should be controlled, but the necessary controls will not constrain the development of land in those few areas to any significant degree.
(b) Civil engineering implications
39.
The
As indicated in paragraph 29 above, land reclamation for the proposed airport site would be created by excavating Chek Lap Kok island (to approximately 9 metres above Principal Datum). critical engineering problem at the site is the presence of a thick layer of mud on the sea bed. Its low bearing capacity could cause reclaimed land to settle if it were allowed to remain under the reclamation. A balance will have to be struck between the least costly method of reclaiming (i.c. leaving the mud in place and accepting the penalties of subsequent settlement) and the more costly but faster method (i.e. removing all the mud by dredging and constructing the embankment on the underlying strata). The Consultants accordingly worked out a preliminary plan for the reclamation of the site based on assumptions of the time available for consolidation of the fill before the final construction of the various elements of the airport layout would need to be completed on the surface. As Phase I would have the shortest available consolidation time, the Consultants propose that the mud over most of this area (apart from the area of the actual sea wall which would be excavated to a firm underlying stratum) would require dredging until it was about three metres in depth, followed by filling on the reduccd layer. Later phases of development could be constructed at a more leisurely pace, and as a longer period could be allowed for settlement of these areas, they could either be dredged to leave a layer of mud five metres in depth or not be dredged at all, depending upon the use to be made of the eventual reclamation (a reduction in the dredging of the mud in the Phase I area of one metre in depth could save as much as $70 million).
G.S. 166
CONFIDENTIAL
機密