11.24 It is estimated that when formed in accordance with the proposals for the development of Tsing Yi, the east Tsing Yi borrow area would produce 3.6 million cu, yds. and the north Tsing Yi borrow area 12 million cu. yds. No accurate figures can be given for the relative proportions of soft and rock without further extensive site investigations being carried out but it appears that there would be a fair proportion of soft in each area.
11.25 The cost of excavating and taking this material from the east Tsing Yi borrow area by barge to the Terminal reclamation is estimated to be $5.20 per cu. yd. for bottom dumping and side tipping to about 3 ft. below Chart Datum. The cost for the north Tsing Yi borrow area is likely to be higher than this. The double-handling involved in unloading barges to place fill above −3ft. C.D. would add an estimated $1.50 per cu, yd. to the cost of filling. If this is not done, fill for reclamation above this level must come from Mainland borrow areas.
11.26 Although the East Tsing Yi borrow area is zoned for industrial use, it is not proposed in this report to take account of sale value of sites formed there, because the requirement for them is comparatively remote.
Dredging
11.27 Four types of dredging would be required in constructing the Terminal:—
(a) Dredging for seawall foundations.
(b) Dredging of the sea approaches.
(c) Dredging to remove soft mud in the reclamation areas.
(d) Dredging to obtain sand for use in seawall foundations.
Sampling of the seabed material has shown that (a), (b) and (c) would be unsuitable sources of reclamation material because of the considerable settlement over a long period that would take place if it were used. This rules it out for use in Gin Drinker's Bay where all reclamation including the Container Terminal would probably be required for early development.
11.28 There are no large deposits of suitable seabed sand in the vicinity for use as reclamation fill and in any case there is enough material available from borrow areas so the use of dredged sand for this purpose is not envisaged.
11.29 There is some sand available for use in seawall foundations in the above area east of Mong Chau but some of this is within the Terminal area and should not be removed. The quantity that would be required for the seawall foundations is estimated at 200,000 cu. yds. and this quantity might be met but if not, sand from elsewhere or possibly decom- posed granite from the borrow areas could be used.
Recommended Sources
11.30 Known sources of free filling material are not expected to provide more than 2 million cu. yds. in the period 1969–1974, whereas the quantity required to complete the present approved Kwai Chung reclamation, not including the Container Terminal area, would be about 3 million cu. yds.
11.31 Although there is at present no timetable for completion of this reclamation, it is con- sidered that since there is already a demand for land in this area, other sources of fill should be found for the Container Terminal and desalination-plant sites. This would mean that about 2 million cu. yds. would be required for the reclamation area already approved plus about 4 million for the additional area now proposed in this Report; of this about 6 million would be for the Terminal and million for the desalination plant.
11.32 The areas of the Terminal in which rock could be tipped would have a capacity of about half the total volume required for the whole site. Because rapid reclamation is likely to be required, however, soft material plus only whatever rock becomes available in the initial excavations would be dumped in the early stages and the overall proportion of rock would therefore be less than half.
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