Vol 20 No 4 (02-2011)
Site Formation for Kai Tak Cruise Terminal Development
Site Formation for Kai Tak Cruise Terminal Development
The Government has committed to developing Hong Kong into a leading cruise hub of the Asia Pacific Area and decided in end September 2008 to take up the construction of the Kai Tak cruise terminal development. As pledged in the Policy Address announced in October 2008, the construction works commenced in 2009 and both the terminal building and the first berth were targeted for operation in mid-2013.
The Kai Tak cruise terminal development consists of three major parts, namely the site formation cum berthing structure implemented by Civil Engineering and Development Department (CEDD), the cruise terminal building by Architectural Services Department and the apron facilities by Electrical and Mechanical Services Department.
Scope of Site Formation Works
The approved project cost is HK$2.3 billion. The site formation works commenced in November 2009 and cover the construction of two alongside cruise berths which are capable of accommodating the largest mega size cruise vessels, with gross tonnage up to 220,000. Works include:
(1) construction of apron area with quay deck about 850m long by 35m wide
(2) installation of 1,227 tubular steel piles of 1.1m and 1.2m dia.
(3) re-construction of existing seawall about 1100m
(4) dredging of about 1.38Mm3 of marine mud over 86ha of seabed
Under the conventional seawall construction arrangement, the extensive back excavation for installation of blockwork seawall and also the sloping seawall will encroach upon the adjoining cruise terminal building site, which is undesirable. The current seawall structure, in form of a vertical walling and consisting of contiguous steel tubular piles, allows parallel construction of the cruise terminal building, thus enabling advancement of its completion date from originally 2014/15 to 2013 to tally with the opening schedule of the first cruise berth. The walling is also designed to integrate and form part of the quay deck structure to achieve cost effectiveness.
The Contractor will install a total of 1,227 reinforced concrete piles (1.1m to 1.2m dia.) in four rows to support the 850m long and 35m wide apron area. Piles located north of the apron area are deeper than those on the south side, approximately 65m in length. The row adjacent to the land comprises about 700 (1.1m dia.) interlocked contiguous steel piles, forming a retaining wall of about 900m long. As afore-mentioned, this vertical walling plays the roles of supporting the quay deck structure as well as retaining the shore, thus, enabling the carrying out of the works for the cruise terminal building concurrently.
The Contractor installs the supporting piles and the vertical walling on land prior to the dredging works between piles and also the re-construction of seawall. As such, no piling works is required to be carried out at sea thus greatly minimizing the effects of inclement weather on the construction progress.
In order to reduce idling time, the Contractor makes use of the steel pile procurement / plant mobilization lead time for removal of the likely existed hard materials / underground obstructions from the filled foundation of the former airport runway at pile locations. This helps smoothen subsequent pile driving works. The construction of quay deck involves extensive piling works and special machineries, such as hydraulic hammers ranging from 12 to 25 tons and reverse circulation drills, are adopted. The 25-ton hydraulic hammer is not commonly used in Hong Kong, and the Contractor has to order one from Sweden to meet the construction requirement.
A total volume of 138 million m3 of mud will be dredged from over 86ha of seabed. The dredging area is divided into Zones A, B and C of different sizes to meet site constraints and programme needs. Dredging works are carried out in Zones A and B first, while the part for Zone C will be carried out after the diversion of existing submarine gas mains there. Two closed grab dredgers, together with two hopper barges of capacity between 800 to 1,000 m3 each, will be used in the dredging works.
Re-construction of Seawall
In order to accommodate mega size cruise vessels of gross tonnage up to 220,000, the Contractor has to dredge the concerned seabed down to -12.15mPD to -13.15mPD. To fulfill the requirements of the Protection of the Harbor Ordinance, the works follow the principle of 浼ero Reclamation? In short, associated with the dredging of seabed, the 1,100 m long seawall will be reconstructed by setting back the existing sloping seawall towards the land direction, so that the 35m wide apron area, including the quay deck, can be constructed within the shore boundary of the original runway. To be environmentally friendly, materials from the demolished old seawall are sorted and reused for the construction of the new seawall. Unsuitable materials will be disposed of at Tuen Mun Area 38 Fill Bank.
Challenge and Solution
The first berth is expected to commission in mid-2013 together with the cruise terminal building. To secure timely implementation of works, CEDD did not allow alternative design in the tender stage. For this purpose, CEDD has considered and reviewed a number of feasible designs and arrived at an optimal version for the tender. CEDD had also reviewed the past weather records and included the projected inclement weather effects on contract duration in the contract documents. As a result, CEDD was able to remove the extension of time clause for inclement weather from the works contract.
In addition, for the sake of protecting the water quality in Victoria Harbour, CEDD conducted an Environmental Impact Assessment for the site formation project and obtained an Environmental Permit from the Environmental Protection Department. As stipulated in the Permit, the dredging works should be carried out in compliance with the following key conditions : to use no more than two dredgers simultaneously; not to exceed 334 m3 per hour and 4,000 m3 per day in dredging rate; to install silt curtains around dredgers ; also to install silt screens at Water Supplies Department掇 six flushing water intakes in the Victoria Harbour; and to monitor the water quality periodically.
Construction Progress and Conclusion
Until end February 2011, over 80% of the quay deck pile work had been driven to set and about 50% of them at the southern end were concreted. As regards vertical walling, over 90% of the pile driving has been completed. The Contractor has now commenced reconstruction of the existing seawall in sections, starting from the southern end.
As one of the Ten Major Infrastructure projects, the new Kai Tak Cruise Terminal will open a new page in the history of the Cruise Tourism in Hong Kong.
Courtesy acknowledgement :
Civil Engineering and Development Department
(Kowloon Development Office)
for the information and pictures provided