2.1
Introduction
2.1.1
In the past 20 years, a great
deal of attention has been given to the redevelopment of the Yau Tong Bay area. On 17.6.1992,
the then Governor directed the Town Planning Board to expand the coverage of the
draft Cha Kwo Ling, Yau Tong, Lei Yue Mun Outline Zoning Plan to include Yau
Tong Bay. Majority of the marine lot owners, in response to the
Government new planning intention, has subsequently agreed to form the joint
venture in cleaning up the dilapidated marine lots and redeveloping the area
into productive and more friendly land uses.
2.1.2
In recycling the dilapidated
bay for a sustainable new land use, high regards have been given to the
residential land use in the surrounding, the accessibility of environmentally-friendly
transit in the door step, the new criteria of environmental protection as well
as public expectation to early urban renewal actions. It is highly
essential to both Government and Community that this environmentally damaging
brownfield site is able to be recycled in a timely manner, thereby removing the
stigma of further contamination, accelerated environmentally degradation and
potential liability associated with the bay area.
2.1.3
Broadly speaking, the
recommended engineering works and the refined development scheme as a result of
careful evaluation of options are able to accomplish and contribute to the
following major public benefits:
·
protects the healthy harbour;
·
aquatic habitat safeguarded;
·
eliminates further
contamination to land, sea and air;
·
removing undesirable,
incompatible and environmentally damaging uses;
·
land reserved for new community
and recreational facilities;
·
a public transport oriented
community;
·
a healthful living environment;
·
use of public fill materials as
main source of fill;
·
sustainable layout design e.g.
school in less noise sensitive locations, step-height pattern, urban-design
approach;
·
sensitive construction program
to eliminate the industrial/residential interface;
·
environmentally friendly
reclaimation method without dredging.
2.2
Site Location and History
2.2.1
The site is located in the
eastern side of Kowloon to the south of the Eastern Harbour Crossing and is in
an area of existing development. The site is bounded on the north and to the east
by Cha Kwo Ling Road and existing development, to the south by Ko Fai Road and
existing development and to the west by Victoria Harbour. Figure 2.1
shows the location of the existing Yau Tong Bay. An aerial photo showing the existing YTB is
contained in Appendix 2A.
2.2.2
The existing YTB is
characterised by two distinct areas – land area of YTB marine lots and seabed
of the bay. The land area, which is
generally level ground and is developed for industrial uses at present. The seabed of the bay is at about -2mPD at
the eastern end of YTB and drops to a maximum of -11.39mPD at the mouth of YTB.
The seabed level was interpolated from the result of preliminary site investigation.
2.2.3
The main source of information
on the history of the site is from the aerial photographs.
2.2.4
The majority of the existing
land areas of the site have been operated as shipyards, timber yards or
sawmills since the late 1950s. The
aerial photograph for 1963 shows the site was completely undeveloped. In 1964, the present coastline was formed as
reflected from Hong Kong Geological Survey (1:20 000) Geological Map Sheet 11 -
Hong Kong and Kowloon. In mid to late
1960s, Cha Kwo Ling Road was constructed westwards along the northern side of
the site and excavation of hillside to the east and south was undertaken.
2.2.5
The high-rise developments to
the east and south of the site were constructed in the late 1960s to mid 1970s.
After that, there was no major change to the site. Currently, most of the Yau Tong marine lots
(YTML) are operated as shipyard, timber yard, sawmill, material storage,
concrete batching plant and industrial building.
2.2.6
The proposed reclamation site
is significantly zoned as Comprehensive Development Area (CDA) on the current
Cha Kwo Ling, Yau Tong, Lei Yue Mun Outline Zoning Plan No. S/K/15/13 (Appendix
2E). At present, the current CDA
zone at Yau Tong Bay covers a total area of about 17.4ha for accommodating
18,000 persons. In the proposed Yau Tong
Bay CDA which was endorsed by Town Planning Board in December 1998, the
population of the development is about 39,000 persons.
2.3
Extent of Reclamation
2.3.1
The existing YTB has been zoned
as Comprehensive Development Area (CDA) on the gazetted Cha Kwo Ling, Yau Tong,
Lei Yue Mun Outline Zoning Plan No. S/K/15/13. The extent of YTB reclamation in
this gazetted OZP is represented by Line
1 in Figure 2.2. This reclamation limit, or simply
named as Gazetted Reclamation, has already been approved by the Metro Planning
Committee (MPC) of the Town Planning Board (TPB) since 1992 when the Yau Tong
Bay was first zoned as CDA. The area of
reclamation within the Gazetted Reclamation is about 9 hectares.
2.3.2
A request for rezoning of Yau
Tong Bay CDA was submitted by David C Lee Surveyors Ltd. on behalf of Main
Wealth Development Ltd. on 1 August 1998 and approval in principle was given on
11 December 1998 (the “1998 Approval”) by the MPC. The approved Master Layout Plan under the
aforesaid planning submission is shown in Appendix 2D. In the aforesaid submission, the extent of
YTB reclamation together with the boundary of Yau Tong Bay CDA were revised
taking into account the coastal alignment of the proposed Western Coast Road
(WCR) which runs from Tseung Kwan O to the South East Kowloon along the
existing coastline. Territory Development Department (TDD) is the project proponent
of the WCR. This coastal alignment of
WCR was recommended in the report of “The Feasibility Study on Alternative
Alignment for the WCR” issued by TDD in 1999 and is named as “WCR – Coastal
Option” currently.
2.3.3
Recently, TDD conducted another
study named “Preliminary Feasibility Study on Tunnel Alignment Option of Tseung
Kwan O Western Coast Road”. The Final
Report of this study was issued in December 2000. The consultant of TDD recommended an
alternative alignment for the WCR, which is named WCR - Tunnel Option. In this option, the WCR starts from Tseung
Kwan O to the South East Kowloon via an inland tunnel instead of running along
the existing coastline. The additional
reclamation at the mouth of Yau Tong Bay for the foundation of the WCR viaducts
is no longer required and the extent of reclamation has to be changed. The study has found that tunnel option for
WCR is preferable to the coastal alignment on environmental, planning and
transport, engineering and programme grounds.
As advised by TDD, from the preliminary programmes, the WCR could be
completed in around 2010/11 and there is still no final decision on which
alignments to be adopted for the WCR.
2.3.4
As there are two different options
for the WCR, the extent of Yau Tong Bay reclamation will be different for each
WCR option. In this EIA Study, the
environmental impacts of the two different reclamation options will be
assessed.
Yau Tong Bay Reclamation based on Western
Coast Road – Coastal Option
2.3.5
Yau Tong section of the WCR –
coastal option is located at the mouth of YTB as shown in Figure 2.2. Originally, the proposed viaducts of the WCR
at this section would be constructed over the sea. In order to minimise the conflict in marine
operation during construction between YTB reclamation and WCR project, and also
to allow a more economical construction method for the viaduct foundation of
the WCR, it is proposed to extend the limit of YTB reclamation such that the
viaduct foundation of the WCR could be constructed on land rather than an
expensive marine structure construction.
Moreover, this reclamation option provides a 30m wide promenade along
the seafront for enjoyment of the public and recreation use. The extent of YTB reclamation based on the
WCR – coastal option is represented by Line
2 in Figure 2.2 and is simply called Full
Reclamation. Line 3 represents the boundary of the proposed YTB CDA under this
reclamation limit. The proposed CDA
boundary has been agreed and approved in principle by the MPC.
2.3.6
In the Full Reclamation option,
the total project area is about 28.5 hectares which comprises 9.6 hectares of
Yau Tong Bay Marine Lots, 0.55 hectare government lots and 18 hectares
reclamation. The reclamation works
consists of 14.2 hectares of Yau Tong Bay and 3.8 hectares seabed areas of the
existing Marine Lots. Layout plan of the Full Reclamation is shown in Figure 2.2a.
2.3.7
As mentioned above, the benefit
of full reclamation is to provide reclaimed land for the foundation of viaducts
of WCR to be built on land in order to reduce the construction cost of the
WCR. In addition, the extra-reclaimed
land can provide a continuous waterfront promenade as recommended by the
government.
2.3.8
The proposed Full Reclamation
option of Yau Tong Bay reclamation is larger than the Minimised Reclamation
option in terms of area of reclaimed land as well as the volume of mud dredging
and bulk filling. The environmental
impacts, especially water quality impact, associated with the Full Reclamation
option within the same construction period and duration, are undoubtedly more
significant than the Minimised Reclamation option or the Gazetted Reclamation.
The Full Reclamation is, therefore, taken as the worst case scenario for the
YTB Reclamation to facilitate the assessment of environmental impacts. Logically, if the Full Reclamation option is
shown to be environmentally acceptable with no insurmountable environmental
impacts, the Minimised Reclamation option, with lesser impact, is also expected
to be environmentally acceptable.
Yau Tong Bay Reclamation based on Western
Coast Road – Tunnel Option
2.3.9
Tunnel alignment is an alternative
option for the WCR and is currently named as “WCR – Tunnel Option”. The occurrence of this option was due to the
strong objection from the public on the proposed coastal option of the WCR. The tunnel alignment of the WCR runs from
Tseung Kwan O to South East Kowloon via an inland tunnel instead of running
along the existing coastline. As such,
the additional reclamation at the mouth of YTB for the foundation of the
coastal option of WCR to be built on will no longer be required. Under the provision of the Protection of the
Harbour Ordinance, the area of reclamation will be minimised. Line 4
in Figure 2.2 is the proposed
alignment of YTB reclamation based on WCR – Tunnel Option and is simply called Minimised Reclamation. The eastern boundary line of YTB CDA is the
same as the reclamation boundary.
2.3.10
The line of Minimised
Reclamation is chosen such that the required reclamation area for the
development is minimised. The proposed
reclamation line aligns the coast from the west of the Site at the existing CED
Maintenance Depot along Cha Kwo Ling Road to the corner of YTML No.1. It will be curved slightly inward towards the
inner part of the bay providing a streamlined coastline to minimize the effect
of the reclamation on the hydrodynamics in the vicinity of the Site. In this option, the total project area is
about 21.5 hectares and the area of reclamation is reduced to 12 hectares
approximately. The layout plan of
Minimised Reclamation is shown in Figure
2.2b.
2.3.11
No matter which reclamation
options, Minimised or Full Reclamation option, will be adopted for the proposed
Yau Tong Bay reclamation, there will be an adjustment to the reclamation limit
currently shown on the OZP No. S/K/15/13.
The proposed Yau Tong Bay reclamation should comply with the presumption
against reclamation principle in the Protection of Harbour Ordinance. The reclamation limit of the two reclamation
options will be proved to be no more than necessary in the following sections.
2.4
Public Benefits of the Yau Tong Bay Reclamation
Concealment of
Contaminated Marine Sediment
2.4.1
The seabed of the existing Yau
Tong Bay is highly contaminated by the discharge or contaminants released from
the existing industrial operations of the surrounding marine lots, such as
shipyards, sawmill or car repairing industry.
The degree of seabed contamination increases from the mouth of Yau Tong
Bay towards the inner part of the bay.
Based on the vibrocore samples collected during the site investigation
in January 1998, the profile of Class C contamination in the YTB seabed is
summarized in Figures 2.3a to
2.3i.
2.4.2
The contour values indicate the
ratio of the measured heavy metal concentration in the Class C
contaminated mud over the classification criteria for Class C contamination as
defined in the EPD TC No. 1-1-92.
Physically, a ratio of 1 indicates that the heavy metal concentration in
the marine mud just reaches the Class C contamination criteria, while
higher ratios suggest that the marine mud is highly contaminated with heavy
metal concentration exceeding the Class C contamination criteria. The contamination profile indicated that the
seabed is highly contaminated by heavy metal, particularly along the Gazetted
Reclamation limit.
2.4.3
Without the implementation of
remedial measures or Yau Tong Bay reclamation, the existing seabed of Yau Tong
Bay is a potential hazard to the future Yau Tong Bay CDA as well as the marine
habitat. Allowing the continuous
operations of polluting industries along the seafront would worsen the current
situation further. The odour arising
from the contaminated seabed may have the possibility to cause nuisance to the
nearby residents especially during summer time.
Apart from the direct impacts to the nearby residents, the contaminated
seabed may also endanger the public indirectly.
For example, fishing at waterfront, especially at promenade, is quite
popular and is a leisure activity of most people nowadays. However, the fishes caught at the
contaminated Yau Tong Bay may be polluted.
Consumption of these polluted fishes would be harmful if not hazardous
to health.
2.4.4
Furthermore, berthing of marine
vessels at Yau Tong Bay may also cause the release of seabed contaminants. When these boats go moorings, their anchors
may disturb the seabed causing the dispersal of contaminants. These released contaminants may migrate
towards the harbour under water current or ship movement.
2.4.5
Removal of contaminated marine
deposit of the seabed is an effective mitigation measure to minimise the
environmental impacts to the existing and future residents of Yau Tong
Bay. However, the limitation on the
quantities of dredging and dumping of contaminated and uncontaminated marine
deposit is quite stringent. Besides,
potentially harmful substances will be unavoidably released from a large scale
dredging process, which may cause serious pollution to Victoria Harbour.
2.4.6
In order to minimise the
adverse impacts of the contaminated seabed to the public and marine habitat, it
is recommended to retain the contaminated marine deposit at its original
position as far as possible and isolate it from the marine environment. Concealing the contaminated Yau Tong Bay
seabed by reclamation is an effective method to achieve this. Although contaminants may release during
dredging of seabed for seawall foundation construction, careful selection of
seawall location and stringent control will minimise the impact during
dredging.
Additional Benefits of Extended Reclamation Options Against Gazetted
Reclamation
2.4.7
The Gazetted Reclamation
boundary covers up only part of the highly contaminated seabed of Yau Tong
Bay. It is believed that the adverse environmental
impacts from the covered contaminated seabed under this Gazetted Reclamation
will be mitigated. However, the
remaining untreated portion of Yau Tong Bay seabed in the Gazetted Reclamation
option is still a potential hazard to the future Yau Tong Bay CDA and the
marine habitat.
2.4.8
As the whole Yau Tong Bay
seabed is contaminated, the extent of the proposed Minimised Reclamation can
effectively isolate the contaminated seabed from the environment. An initial sediment sampling and sediment
testing reveal that the toxic chemical compound contained within the portion of
extend reclamation (area between Gazetted and Minimised Reclamation) was higher
than the adjacent area immediately east to the proposed reclamation line.
2.4.9
As mentioned above, the seabed
along the Gazetted Reclamation limit is highly contaminated by heavy metal
comparing with Minimised or Full Reclamation options. Dredging of marine deposit for the
construction of seawall foundation along this alignment might result in a high
release of contaminants and harmful substances (e.g. heavy metal) into the
Harbour. Other environmental problems,
such as the treatment and disposal of the highly contaminated dredged material,
might also arise. In this connection,
the Gazetted Reclamation limit is considered not an environmentally suitable
alignment for YTB reclamation.
2.4.10
The Minimised Reclamation
covers up almost the whole Yau Tong Bay which can effectively contain and
prevent all contaminants or poisonous substances in the highly contaminated Yau
Tong Bay seabed from migrating into the marine water. The Minimised Reclamation limit, not only
helps to achieve the important community development objectives, but to
eliminate the health hazards due to existing water pollution and soil
contamination.
2.4.11
Line 3, represents the boundary
of CDA in the WCR – Coastal Option, which is considered to be the best
reclamation limit amongst the three reclamation options in view of minimizing
the potential hazard of the existing seabed contamination on the public. It covers up the whole contaminated Yau Tong
Bay seabed and the degree of seabed contamination along its seawall is lower
than those seawall alignments of Gazetted and Minimised Reclamation
options. However, under the Protection
of the Harbour Ordinance, it involves a greater area of reclamation than the
option of Minimised Reclamation. With
the consideration on the implications of seabed contamination, area of
reclamation and the above-mentioned elements, the Minimised Reclamation is a
more preferable extent for YTB reclamation.
Improvement to the
Environment of Yau
Tong Bay
2.4.12
Yau Tong Bay is currently
characterised by industrial operations such as shipyards, timber yards,
sawmills, construction materials storage, industrial building and vehicle
repair workshops. The existing
environment of YTB is considered poor and is suspected to be polluted by the
existing industry.
2.4.13
Several large scale housing
projects in the vicinity of Yau Tong Bay have already been commenced or
substantially completed. Residents will move
in gradually. Reclamation of Yau Tong
Bay and the subsequent development on the reclaimed land provide an opportunity
to remove the existing polluting industrial operations at Yau Tong Bay. It is undoubtedly to the benefits of
everyone who lives or studies in Yau Tong for the bay to be reclaimed such that
the nuisance caused by the polluting industrial operations could be removed as
well.
2.4.14
The decommissioning of
shipyards and demolition of building structures in the YTB reclamation project
not only relieve the pollution problems such as noise impact, air quality
impact, water quality impact, land contamination and visual impact, caused by
the existing industries, but also provide land to achieve important community
development objectives, such as provisions of schools and open space for
continuous seafront promenade.
Reduction of I/R
Interface Problem
2.4.15
Some of the owners of YTML have
not reached an agreement with the Joint Venture. The lots of these dissenting owners are YTML1,
2-4, 25-27, 73 and 74 which are currently operated as shipyards, sawmill,
material storage or industrial building.
The opportunity for continued operation of these marine-related
industrial activities is an unlikely event in the context of YTB redevelopment
and loss of marine access. The
coexistence of industrial operations in the vicinity of residential area in the
future CDA however remote in Hong Kong’s market economy has been assumed for
analysis and is so called industrial / residential (I/R) interface. Environmental impacts generated from I/R
interfacing problems are presented in the Package 2 EIA Study – “Engineering
Feasibility Study for the Comprehensive Development at Yau Tong Bay”.
2.4.16
Removal of marine access is a
catalyst to expedite the cessation of these current industrial operations. Indeed, the proposed reclamation lines
(either Full Reclamation or Minimised Reclamation) will remove the marine
access of all Yau Tong marine lots completely.
The change in Yau Tong Bay creates an incentive for the existing
industrial landowner including those dissenting owners to redevelop their
properties as part of the CDA and the whole area being developed under the
control of the Town Planning Board. In
fact, Yau Tong Bay reclamation provides an opportunity not only to remove the
adverse environmental impacts from existing industrial operations to existing
and future nearby residents, but also to resolve the problem of I/R interface
between the dissenting lots and future CDA.
2.4.17
However, the Gazetted Reclamation
option cannot completely resolve the problem of I/R interface. From Figure
2.2 and the Draft OZP Plan no. S/K15/13, it is noted that the Gazetted
Reclamation (Line 1) abuts an industrial zone where two existing industrial
building, one is on the dissenting lots of YTMLs 73 and 74, a saltwater pumping
station and a gas pigging station are located and their marine access still
exists. If these two industrial land parcels
remain as industrial uses without any plan for rezoning, it will represent a
source of I/R interface problem to the CDA.
2.4.18
If the CDA boundary is extended
to the proposed reclamation line (either Full Reclamation or Minimised
Reclamation), there creates an incentive for the existing industrial landowner
to redevelop their property as part of the CDA.
In the absence of the incentive for the individual owners to jointly
redevelop the Yau Tong Bay and carrying out the reclamation, the continuous
operation of the shipyards will definitely frustrate the emerging role,
changing nature and scenic value of the harbour, in particular the visual
impact of its gateway location at the eastern inner harbour. The impact to the adjoining housing
development will be substantial and considerable. These existing uses may become an
environmental nuisance to the neighboring Housing Authority’s housing estates
upon completion as well as the private residential development south of Ko Fai
Road.
2.4.19
Contrarily, in the scenario of
Minimised Reclamation (Line 4), the marine access for the dissenting lots is
extinguished and the dissenting lots are in close proximity to the CDA. This will encourage the dissenting owners to
cease their current industrial business and change to another more profitable
business.
2.4.20
An overly cautious approach to
safeguard the existence of those incompatible land uses not only generate
further environmental risk and neighborhood distress, chilling the urban
renewal objectives but is against the market economy principle that may
necessitate public subsidy in terms of quality housing and premium assessment.
Enhancement to Open
Space Provision
2.4.21
The Central and East Kowloon
Development Statement (CEKDS) study revealed a finding that there is a general
shortage of open space in the Kwun Tong area.
According to the public consultation on “Planning Study on the Harbour
and Its Waterfront Areas”, public benefits/access shall be emphasized for all
development facing the harbour whereby the use of waterfront promenade and
recreational / tourism facilities shall be encouraged as part of the
redevelopment along waterfront to provide public open space for access and
enjoyment of the public. The promenade
will also serve as a mode of transport that facilitates travel for pedestrians
and possibly cyclists. Cycle routes may
be provided to promote tourism and encourage travel in an
environmentally-friendly manner.
Moreover, the promenade will also be suitable to house various
utilities. The proposed development on
the reclamation provides a natural sightline of the waterfront and will provide
an ideal space for passive and even active recreation uses.
Additional Land
Resource to GIC Facilities
2.4.22
Another shortcoming within the
Kwun Tong area is the inadequate provision of school facilities. Due to insufficient land allocation of
educational purpose in Kwun Tong, the proposed development will be able to
provide land resources for school provision (total 8 schools in the proposed
Yau Tong Bay Development), on top of the school facilities already provided
within the gazetted CDA to support the population growth in Yau Tong and the
surrounding areas.
2.5
Description of Scenarios with or without the
Project
2.5.1
Significant portion of the
reclaimed area in this project has already been zoned as Comprehensive
Development Area (CDA) under the current OZP No. S/K/15/13. This proposed project is aimed to provide
land and infrastructures for the future comprehensive development in order to
accommodate 39,000 peoples approximately.
2.5.2
The Site comprises more than 20
marine lots on which various types of industrial activities are still
active. Some of the industrial
operations, for instance, shipyards and car repairing workshops are identified
as potential source for causing land contamination and all the other industrial
operations at YTB are suspected to be the sources of pollution.
2.5.3
With the implementation of this
project, the existing scattered, low-rise industrial building structures will
be demolished and replaced by residential and commercial buildings. In fact, these scattered industrial buildings
create an unpleasant visual impact to the environment. The decommissioning of shipyards will
probably relieve the environmental impacts on land contamination, noise, water
quality and air quality.
2.5.4
The Coastal Option and Tunnel
Option are two possible options for the alignment of the WCR, there is still no
final decision on which alignment to be adopted for the WCR. If the Coastal Option is adopted, the
viaducts of the WCR will be built at the mouth of Yau Tong Bay. In current planning, the viaducts of WCR at
Yau Tong section will be built over water by the means of marine piles. The implementation of Yau Tong Bay
reclamation will extinguish the marine access to the existing marine lots and
will provide sufficient land for the foundation of WCR (Yau Tong section) to be
built on land. Through this arrangement,
the construction cost of the WCR can be reduced. Moreover, as the marine access is no longer
required, the viaduct level of the WCR can probably be reduced. The land underneath the WCR together with the
proposed seafront promenade can be acted as recreation area for the public, for
example, a continuous seafront promenade.
2.5.5
If reclamation and subsequent
development of Yau Tong Bay not proceed, it will become a potential hazard to
the nearby residents and student. The
existing Yau Tong Bay engulfed by marine lots has now become a pool of stagnant
water and a source of nuisance.
2.5.6
Without this project, the
industrial uses on the existing marine lots such as ship repairing, vehicle
repairing, sawmill, industrial building, concrete batching plant and
construction material storage may continue their operations for a very long
period. No one can estimate when they
will be ceased.
2.5.7
Housing Department has already
commenced many large scale housing projects in the vicinity of the Site. As a matter of fact, the stagnant water in
the bay, together with the current industrial operations will cause nuisance to
the residents of the housing estates when completed. The harmful pollutants generated by the
highly contaminated industry will affect the health of existing and Yau Tong
Bay future residents. Additionally,
there will be some new schools opposite to Cha Kwo Ling Road of which one is in
operation. These schools are vulnerable
to noise nuisance generated by the operations on the marine lots. It is foreseeable that complaints from future
nearby residents against the nuisance will pose a problem and pressure for the
government.
2.6
Construction Activities
2.6.1
Except the quantities of works,
the construction method, period and activities of the Full Reclamation and
Minimised Reclamation options are basically the same. Reclamation of Yau Tong Bay consists of two
main types of works - Marine Works and Lands Works.
Marine Works
2.6.2
The Yau Tong Bay reclamation
will involve the construction of total length 300 metres new seawall at the
western side of the Site facing to Victoria Harbour. However, the type of seawall, whether it is a
vertical caisson seawall, sloping seawall or sloping seawall with a quay deck, will
be determined in the detailed design stage.
The new seawall will be situated on dredged foundation which will be
formed by removing the soft marine deposit.
Rockfill will be placed onto the dredged seawall trench to form the
foundation of seawall. Vertical seawall
formed by precast concrete blocks or sloping seawall will be built on the
dredged seawall foundation.
2.6.3
The recommended reclamation
scheme and phasing were proposed based on engineering, amount of available
land, programme and cost consideration. This option can be modified as the
study progresses dependent on imposed constraints.
General Reclamation Areas
Alternatives on Reclamation Method
2.6.4
The seabed of the existing Yau
Tong Bay is covered by a thick layer of soft marine deposit. Without any treatment for the marine mud and
allowing the mud to consolidate naturally under the new fill of reclamation is
an exceedingly slow process and resulting post development settlement which is
unacceptable to the progarmme of the proposed development. Treatment of mud stratum is necessary in
order to cope with the development programme.
There are two main engineering methods for minimizing the settlement
resulting from reclamation. These two
methods are dredged reclamation and “drained” reclamation methods.
Dredged Reclamation
2.6.5
Dredging is a direct method for
removing the soft material on the Yau Tong Bay seabed. It is a simple and rapid
way to expedite the settlement rate of reclamation. The removed soft marine deposit will be replaced
by a suitable filling material usually sandfill or rockfill. Reclamation by bulk filling can proceed after
the removal of marine mud. The volume of
dredged material depends on the area of reclamation and the thickness of marine
deposit. From the results of site
investigation carried out in January 1998, the thickness of marine deposit in
existing Yau Tong Bay varies from 4m to 8m approximately. The area of reclamation is about 18 hectares
for Full Reclamation option (12 hectares for Minimised Reclamation
option). If the dredged reclamation
method is used, the estimated volume of dredging for Full Reclamation will be
about 1,080,000m3 (for Full Reclamation).
2.6.6
As the seabed of Yau Tong Bay
is suspected to be contaminated, the quantities of dredging shall be reduced as
far as possible in order to minimize the release of contaminants into the
harbour. Moreover, the disposal of
surplus dredged material, no matter contaminated or uncontaminated, would
definitely induce another environmental problems. Leakage of dredged material during
transportation to disposal by marine barges is another environmental concern
especially for contaminated materials.
As the quantities of dredged material would be tremendous, a huge number
of trips of marine barges for disposal of the dredged deposit would be
required. The chance of leakage will be
increased. Therefore, dredging would be
recommended only when essential in engineering points of view and shall be
reduced to a minimal. As such, dredged
reclamation method is not recommended to be adopted for Yau Tong Bay
reclamation although it is a fast and simple method of construction.
“Drained” Reclamation
2.6.7
It is recommended to use a
“drained” reclamation with preloading for general reclamation areas of Yau Tong
Bay. Drained reclamation relies on the installation of additional drainage
paths into the soft compressible marine deposits. These additional drainage
paths shorten the overall drainage path of the soft compressible material
resulting in quicker consolidation. Preloading comprises subjecting the ground to
a temporary load which is greater than the envisaged final loading. The aim of
preloading is to speed up the rate of settlement and slightly over consolidate
the ground, thus minimize the amount of residual settlement and enable the site
to be handed over for other construction activities as early as possible. Although drained reclamation involves a more
complicated construction procedures and requires more resources, this
reclamation method can greatly reduce the quantities of dredged material and
requires lesser filling material comparing with the dredged reclamation method,
which is considered more environmental friendly. The details of the recommended scheme are
presented below:-
·
Place Geotextile across the
area to be reclaimed to prevent the formation of mud waves.
·
Place sand blankets of 0.5m,
0.5m and 1.0m thick across the site. Placement of sandfill by Grabbing or
Pelican Barge.
·
Installation of vertical band
drains as a marine operation.
·
Bulk filling to +2.5mPD, or an
appropriate level which breaks the mean high water mark. Bottom dumping of fill material should be
employed while there is sufficient depth of water. After that, placement of filling material can
be carried out by Pelican Barge.
·
Bulk filling to preload
level. Placement of fill by Pelican
Barge with dump trucks and loader.
·
Surcharge period.
·
Remove preloading mount to
formation level once the anticipated settlement of the preloading mount has
been achieved.
·
Handing over the Site for utilities,
infrastructure and foundation works.
2.6.8
There are three reasons to
place geotextile over the seabed to be reclaimed. Firstly, to minimize seabed disturbance
during filling processes and therefore reduce the amount of suspended solids in
the water column. Secondly, to reduce the amount of intermixing between the
seabed deposits and the placed fill material.
Thirdly, to minimize the risk of mud waves occurring. The placement of a thin layer of sand
blankets also helps to reduce the risk of mud waves occurring.
Alternatives on the Use of Filling Material
2.6.9
In order to have a stable
supply of filling material for reclamation, imported sand fill from PRC by
barge is indeed a good selection for reclamation material. Because of the physical properties of sandfill,
the rate of settlement of sand filled reclamation is expected to be faster than
the other filling material. Also, less
difficulty would be expected during reclamation.
2.6.10
Although sandfill is quite a
good material for reclamation, it is recommended to use public filling material
whenever possible. Except the need of
rockfill for the foundation of the new seawall and the 1.5m thick drainage
blanket (sand Blanket) directly overlying the marine mud which are considered
essential in the light of geotechnical requirements, the use of public filling
material generated by local construction industry will be maximized for Yau
Tong Bay reclamation in order to alleviate the acute shortage of public filling
capacity in Hong Kong. The average
filling rates of bulk filling are shown in Section 2.7.2.
The estimated volume of imported public filling material for reclamation
including preloading mound is about 1.85Mm3. The supply of public filling material will be
arranged with the Public Fill Committee prior to the commencement of
reclamation in order to ensure stable supply of public filling materials.
2.6.11
From engineering points of
view, both sandfill and public filling material are suitable for Yau Tong Bay
reclamation. Considering the
above-mentioned, the use of public filling material is recommended. However, in case of unstable or insufficient
supply of public filling material, sandfill will be used as a supplement to
public fill for reclamation.
Reclamation above the Submarine Water Main and
Gas Pipelines
2.6.12
The WSD submarine cross harbour
fresh water main runs from the seafront of Yau Tong Bay in Cha Kwo Ling Road
adjacent to the existing Cha Kwo Ling Saltwater Pumping Station to Quarry
Bay. The water main provides potable
water to one-third of Hong Kong from the Diamond Hill reservoir. The Hong Kong China Gas Company (HKCGC) twin
600mm diameter cross harbour submarine gas pipelines run from Tai Koo Shing and
pass through the gas pigging station installation on Cha Kwo Ling Road serving
a large area of Kowloon. It is
understood from WSD and HKCGC that the water main and gas pipelines form an
important part of the distribution network.
Diversion or reprovisioning of the pipelines is a time-consuming process
and will cause disruption to the existing network. Both WSD and HKCGC do not accept reclamation
to be applied directly above their submarine pipelines. As mentioned in the above sections, it is
understood that reclamation can bury the contaminants in the seabed and prevent
them from migrating into open water.
However, due to the constraint posed by the submarine pieplines, it is
proposed not to divert these pipelines in order to reclaim this area.
2.6.13
No matter which reclamation
options will be adopted, it is recommended that a removable concrete decking
supported on bored piles should be constructed above the submarine WSD 1400mm
diameter fresh water main and twin 600mm diameter gas pipelines. The decking is removable in order to enable
emergency repair or maintenance of the submarine gas pipelines and
watermain. An access opening of minimum
35m x 10m will be provided in the piled deck to allow for routine maintenance
of WSD Cha Kwo Ling Saltwater Pumping Station which is located adjacent to the
decking. Rubbish, if trapped underneath the decking, can be easily removed
through this opening on deck. Also, it
can prevent the accumulation of gas trapped underneath the deck in case of
leakage of gas in the submarine pipelines.
2.6.14
The function of the decking is
to provide an open space to form a continuous promenade should government
considers that a waterfront promenade is desirable. Besides, the most important purpose of the
decking is to create a smooth coastline with adjoining seawalls as well as
hiding the esthetically unattractive bored pile seawall, between the new
seawall facing the harbour and the existing seawalll of the CED maintenance
depot. Without the concrete decking,
there will be an abrupt change in the coastline formed by the small embayment
formed by the new vertical bored pile seawall and the existing seawall of the
CED depot.
2.6.15
The removable concrete decking
is supported by a series of bore piles.
As the release of marine deposit during construction of bore piles is
confined by the pile casing, it is considered that the environmental impacts in
terms of water quality generated by bore pile construction is minimal comparing
with dredging for conventional seawall foundation. The decking is formed by precast concrete
beams or slabs such that the casting of beams or slabs can be carried out in
the precasting yard outside the Site, may be in mainland China. The construction of bore piles for the
decking could be commenced after the completion of bore piled seawall of Phase 2
reclamation. As the removable decking is
not a critical construction activity and the construction period is quite
flexible, it can be carried out at any time after the commencement of the
reclamation depending on the construction sequence and available resources
proposed by the contractor during construction stage.
2.6.16
The removable concrete decking
will form part of Yau Tong Bay reclamation which may be implemented and
maintained by the Project Proponent of the project. Construction and maintenance cost of the
decking may be premium deductible.
Reclamation under Roads and Utility Reserves
2.6.17
It is recommended that the same
scheme outlined above shall be applied for the reclamation beneath proposed
internal roads except the fill material shall be compacted to achieve an over
consolidation ratio of 1.2 under working conditions in the marine deposit. This will reduce the residual settlements.
Reclamation at Proposed Box Culverts
2.6.18
It is recommended that the
marine deposit at the foundation of the two main box culverts should be dredged
to minimize the settlement of the culverts.
The preloading of culvert foundation will be started after bulk filling
to the required level. Details of
culvert construction will be determined and agreed with DSD in detailed design
stage.
Permanent Seawall (Except the Seawall adjacent
to the Submarine Pipelines)
2.6.19
Except the seawall adjacent to
the submarine pipelines, all permanent seawalls are recommended to be founded
on dredged foundations.
2.6.20
Seawalls facing to Victoria
Harbour will be designed as wave absorbing seawall with a wave-reflecting
coefficient of less 0.5 in accordance with WBTC 3/95. In order to achieve this, the use of sloping
seawalls or vertical caisson seawall is recommended. At locations where berthing of marine vessels
is allowed, either a piled quay deck over the sloping seawall or a caisson
seawall should be constructed. Details
of sloping seawall and vertical caisson seawall are shown in Appendix
2F.
Permanent Seawall adjacent to the Submarine
Pipelines
2.6.21
Bore piled seawall in
accordance with WSD requirements is recommended for the permanent seawall
adjacent to the existing submarine pipelines.
This type of seawall will be costly and time consuming to construct,
however it is the only solution which can satisfy the requirements of WSD
currently. The bore piled seawall is one
of the possible solutions but it is not the only solution. Alternatives to this costly type of seawall
should be investigated during the preliminary or detailed design stages if
necessary.
2.6.22
A temporary dredged seawall
should be constructed in accordance with the WSD’s allowable dredging
limit. This temporary seawall is used to
enclose the main body of the reclamation while the bored pile seawall is being
constructed.
Temporary Reclamation Edge Structures
2.6.23
As described in Section 2.5, it is
proposed to phase the majority of the reclamation on a rolling programme. This
should preclude the need for temporary reclamation edge structures. However, if there is a requirement for a
temporary reclamation edge structure, one of the following should be used:
vertical cantilever (braced bulkhead); vertical seawall; sloping seawall; or a
1:10 to 1:15 “beach” slope.
2.6.24
The leading edge of the
reclamation should generally be formed using a 1:10 to 1:15 “beach” slope.
2.6.25
The southern edge of Phase 1a
reclamation should be formed using a temporary sloping seawall which utilises
the dredged foundation of the permanent culvert. This will ensure a clear
marine access to the remaining reclamation construction.
2.6.26
The interface between the WCR
reclamation and the Yau Tong Bay reclamation should be formed using a sloping
seawall.
Temporary Culvert / Channel
2.6.27
It is proposed to provide a
temporary culvert/channel along the existing eastern and southern seawall of
Yau Tong Bay to collect and convey the discharge form the outfalls of the
existing stormwater box culverts into the harbour. This structure should utilise the existing
seawall foundations wherever possible. The temporary culvert/channel should be
constructed at the beginning of reclamation to prevent stormwater from the
existing culvert from discharging into the embayment formed by permanent and
temporary seawalls, otherwise, the polluted stormwater trapped in the embayment
would affect the environment.
Lands Works
2.6.28
The area surrounding Yau Tong
Bay currently consists of low-rise industrial building structures which include
shipyards, concrete batching plant, timber yards and sawmills. In order to allow the re-development of Yau
Tong Bay, these existing building structures will be decommissioned and
demolished. The major land works
involved in the reclamation of Yau Tong Bay are the
demolition of existing building structures and land decontamination works which
will be discussed in Section 7.
2.7
Reclamation Phasing
Alternatives on Reclamation Phasing
2.7.1
Several alternatives of
reclamation sequences have been considered in the early stage of the EIA study
of which two options are selected for further investigation.
Option I:
2.7.2
In this option, both temporary
(adjacent to existing submarine pipelines) and permanent (facing to the
harbour) seawalls will be built concurrently with the main body of the reclamation
in order to shorten the construction period.
However, as the seawalls is still under construction during bulk
filling, there is no physical barrier to prevent the dispersal of filling
material into the harbour except some silt screens or curtains. Although this is a fast track construction
method, it would induce greater impact to the water quality of Victoria Harbour
as well as the overall environmental. As
such, this reclamation sequence is not recommended.
Option II (Preferred
Option):
2.7.3
The following is a list of the
assumptions and imposed constraints considered when formulating the reclamation
phasing in this option:
·
Reprovision of the drainage
culverts discharging into Yau Tong Bay.
·
Provision of land for the
Coastal Option of Western Coast Road (WCR) construction
·
The WSD and Hong Kong and China
Gas Co. pipe reserve in the northwest corner of the Site.
·
The reclamation works for this
project will commence on February 2004.
·
The temporary channel / culvert
has to be constructed before the bay is fully enclosed.
·
The bay should be fully
enclosed, except for a 50m wide marine access, before the main filling works
commence.
·
An average filling rate
of 4,000 m³ per day, with a maximum of 10,000 m³ per day.
2.7.4
The assumed average filling
rate is based on :-
|
|
Filling Activity
|
Filling Method
|
Filling Rate
|
|
1.
|
Sand Blanket
|
Grabbing or Pelican Barge
(Delicately)
|
1,000 m³/day
|
|
2.
|
Bulk Filling below ‑4mPD
|
|
10,000 m³/day
|
|
3.
|
Bulk Filling above ‑4mPD
|
|
1,000 m³/day to 7000 m³/day (Average
4,000³/day)
|
2.7.5
Placement of filling material
for the sand blanket is of small amount.
After placement of the sand blanket, level of the western portion of the
bay will be probably below -4mPD, therefore, bottom dumping can be carried out
in this area. The average filling rate of the Pelican barges has been used
instead of a higher value to counter act the uncertainty in the supply of
filling materials under the following possible situations during construction.
They are :-
·
Location and number of barging
point of public fill, and also quality of public filling materials.
·
Size and number of marine
vessels available.
·
Limitation on the number of
marine vessels that allowed by Marine Department of the Government of HKSAR to work at Victoria
Harbour.
·
Congestion within Yau Tong Bay
with other activities, i.e. marine installation of vertical band drains.
2.7.6
In order to satisfy the above
constraints, three construction phases have been proposed (Figure 2.4a-d). Phase 1 is the main body of the
reclamation. Phase 2 is to reclaim the
remaining area between the bore piled seawall and the temporary seawall. Phase 3 is the concrete decking construction
above the submarine pipe.
2.7.7
Phase 1 will form the main body
of the reclamation. The lines within the Phase 1 reclamation area represent the
leading edge of the reclamation at each sub-phase. Phase 1a is specifically reclaimed to provide
land for the WCR construction. Except
for Phase 1a, the edge of each of the other sub-phases (1b, 1c, and 1d) should
be formed by a 1:10 to 1:15 “beach” slope.
A temporary sloping seawall should be constructed along the southern
edge of Phase 1a reclamation by utilizing the dredged foundation of the
proposed culvert extension.
2.7.8
Phase 2 of the reclamation is
to reclaim the portion of land between the temporary seawall and the permanent
bore piled seawall adjacent to the submarine pipelines.
2.7.9
Phase 3 of the reclamation is
the removable concrete decking above the submarine pipe reserve.
2.7.1
The reclamation programme is
presented in Appendix 2B.
2.8
Designated Projects
2.8.1
The Reclamation of Yau Tong Bay
falls under Schedule 2, Part 1, C - Reclamation, Hydraulic and Marine
Facilities, Dredging and Dumping” of the EIA Ordinance. Under the item C.2 of the aforesaid category,
this project is described as reclamation works (including associated dredging
works) more than 1 ha in size a boundary of which is less than 100m from a
seawater intake point”.
2.8.2
The decommissioning of existing
shipyards at Yau Tong Bay also falls under Schedule 2, Part II, item 17 – A
facility for ship building or repairing more than 1 ha in size or with a
lifting capacity in excess of 20 000 tonnes.
2.9
Scope and Overall Approach
to the EIA Study
2.9.1
The scope of work for the EIA
Study is detailed in the Study Brief No. ESB-0010/1998 attached in Appendix 2C. In accordance with the Study Brief,
environmental issues related to the following aspects are to be addressed:
·
noise impact;
·
water quality impact;
·
waste management implications;
·
land contamination impact; and
·
visual and landscape impacts.
2.9.2
The scope also includes recommendation
of mitigation measures, identification of residual impacts and proposing
environmental monitoring and auditing (EM&A) requirements for the
project. The assessment methodology
adopted in the EIA Study is in accordance with the TM on EIA Process. Where
quantitative predictions have been provided, the modeling methodology, input
parameters and method of calculation have been discussed, reviewed and agreed
with the relevant Government Departments.
It should be noted that worst-case scenarios or conservative assumptions
have been considered where appropriate.
