16.1 Population and Environmental Sensitive Areas Protected
16.1.1.1 As described in Section 1.5, CEDD commissioned the TKO Study in 2002 to formulate a comprehensive plan for further development of TKO and improvement of its overall design with a view to building TKO into a new town that can boast of its convenience, vibrancy, distinctive urban design and quality living environment. As an integral part of the TKO Study, the long-term transport need of TKO had been examined.
16.1.1.2 The TKO Study identified that the existing TKO Tunnel would have insufficient capacity to cater for projected traffic flow to be generated from further population intake and industrial developments in TKO. It recommended that a new external road network comprising the CBL and TKO-LT Tunnel should be provided to meet the anticipated traffic flow. The TKO Study was substantially completed in 2005 with endorsement of its recommendations.
16.1.1.3
The consequence of
not proceeding with the Project would have been a
constraining factor upon the planning and development of Area 87 and Area 137
due to traffic congestion along
16.1.1.4
With the CBL and Route 6, including TKO-LT Tunnel, the journey time between TKO Area 86 and Kowloon would be
significantly reduced. Currently, from the junction of
16.2 Approaches Adopted to Avoid Environmental Impacts
16.2.1 The EIA Study for Further Development of Tseung Kwan O Feasibility Study concluded that a route option without CBL would be environmentally undesirable and was not suitable for further consideration. In the absence of CBL and TKO-LT Tunnel, there would be increased traffic through TKO Town Centre, overloading its road network and causing heavy congestion. Higher traffic flows through TKO Town Centre will result in greater levels of air and noise impacts. Therefore, with the development of CBL and TKO-LT Tunnel, environmental impacts due to increased traffic and congestion through TKO Town Centre have been avoided.
16.3 Approaches Adopted to Minimize Environmental Impacts
16.3.1 Approaches adopted to minimize environmental impacts have been one of the key considerations throughout the entire project development and design. The following sections provide a summary of key approaches adopted.
· Route alignment and design option evaluation to develop a feature bridge design for CBL and become a landmark for TKO;
· Deployment of large span piers to minimize construction works and work front;
· Addition of ‘green features’ such as footpath and cycle track to connect to existing and planned cycle tracks; and
· Deployment of construction methods such as off-site precast segmental construction, off-site fabrication and non-dredge method.
Route alignment and design
option evaluation to develop a feature bridge design for CBL and become a
landmark for TKO
16.3.1.1
According to “Further
Development of Tseung Kwan O Feasibility Study – Final Topical Study Report:
Cross Bay Link” (2005), the four route alignment options are appraised broadly
in terms of traffic performance, compatibility with land use planning intentions,
and potential environmental impacts. As result, Scheme A (Bridge Arrangement) would be preferred as its compatible with the land use
planning for TKO, met the necessary functional requirements for this road link
and would also perform best in terms of technical criteria
including environmental performance.
16.3.1.2
From an evaluation of a
long list of bridge design options, six were identified to be technically
feasible for the project and shortlisted by the
Final Design Options Review Report (2010).
Consultation with the government departments and the Sai Kung District
Council in November 2009 confirmed the six design options to be taken forward
for public consultation. As result, Design Option 5, the Eternity Arch, gained
the most support and was therefore subsequently taken forward as the preferred
option for CBL. Details refer to Section 3.3.
Large span pier design to
minimize works front and construction works
16.3.1.3
The
span of the piers for CBL ranges from 75m to 200m. This
span is larger than the normal 50m span for bridge structures. With the larger span, a smaller number of
piers are required, and thus the works front number and construction works is
reduced. Associated impacts on marine
water quality and marine habitat loss are therefore minimised. Details refer to Sections 8 and 10,
respectively.
Addition of ‘green
features’ such as footpath and cycle track to connect to existing and planned
cycle tracks
16.3.1.4 Several recreational facilities were also proposed in the TKO Study to further enhance the living environment of the TKO residents. These include a riverine park along the Eastern Channel, a waterfront promenade in town centre south, an area for water sports and recreational facilities at the TKO Stage I Landfill site, and the construction of more cycle tracks in the new developments. CBL will provide a new cycle track which will be connected to the existing and other planned cycle tracks to form a complete loop in TKO. In addition to CBL, new footbridge located at the Eastern Channel, Southern Bridge, is being planned to complement the existing Northern Bridge.
Deployment of construction methods such as off-site precast segmental construction, off-site fabrication and non-dredge method
16.3.2
Off-site construction
offers many environmental benefits. In general, by moving
construction away from the site, potential nuisance to local residents and the
impact on the local environment would be reduced.
However, the purpose of the off-site fabrication is not to transfer the
problems elsewhere. The
concrete pre-casting and steel fabrication yards in
16.3.2.1
Non dredging works are
envisaged for the construction of CBL.
Piling and pile cap construction would occur in three different sections
for the
16.4 Approaches Adopted to Mitigate Environmental Impacts
16.4.1 With the development of CBL and TKO-LT Tunnel, environmental impacts due to increased traffic and congestion throughout TKO Town Centre have been avoided, thus, providing economic and social benefits to the surrounding communities. However, due to the inherent environmental impacts due to construction activities, CBL has minimized its environmental impacts where possible. Where the impacts could not be minimized, efforts have been made to mitigate the impacts as far as practicable. The EIA has recommended a package of mitigation measures that would be required. The Environmental Mitigation Implementation Schedule in the EM&A Manual has clearly stated the details of such mitigation measures, the timeframe and the implementation agents. Some of the key mitigation measures are discussed in the following sections.
16.4.2 Measures adopted to Mitigate Air Quality Impacts
16.4.2.1 In order to reduce dust emission from the Project and achieve compliance with the TSP criteria at ASRs during construction phase, mitigation measures in form of regular watering under a good site practice should be adopted. In addition to the watering and required intensity, the Contractor will also be obliged to follow the procedures and requirements given in the Air Pollution Control (Construction Dust) Regulation.
16.4.2.2
In accordance with the Air Pollution
Control (Construction Dust) Regulation, the following
dust suppression measures should also be incorporated by
the Contractor to control the potential for dust nuisance
throughout the construction phase:
·
Any
excavated or stockpile of dusty material should be covered entirely by impervious sheeting or sprayed with water to maintain the entire surface wet and then removed
or backfilled or reinstated where practicable within 24 hours of the excavation
or unloading;
·
Any dusty materials remaining after
a stockpile is removed should be wetted with water and cleared from the surface
of roads;
·
A stockpile of dusty material should
not extend beyond the pedestrian barriers, fencing or traffic cones;
·
The
load of dusty materials on a vehicle leaving a construction site should be
covered entirely by impervious sheeting to ensure that the dusty materials do
not leak from the vehicle;
·
Where
practicable, vehicle washing facilities with high pressure water jet should be provided at every discernible or
designated vehicle exit point. The area
where vehicle washing takes place and the road section between the washing
facilities and the exit point should be paved with
concrete, bituminous materials or hardcores;
·
When
there are open excavation and reinstatement works, hoarding of not less than 2.4m high should be provided as far as practicable along the site boundary with provision for public crossing. Good site practice shall also be adopted by the Contractor to
ensure the conditions of the hoardings are properly maintained throughout the
construction period;
·
The portion of any road leading only
to construction site that is within 30m of a vehicle entrance or exit should be
kept clear of dusty materials;
·
Surfaces
where any pneumatic or power-driven drilling, cutting, polishing or other
mechanical breaking operation takes place should be sprayed with water or a
dust suppression chemical continuously;
·
Any area that involves demolition
activities should be sprayed with water or a dust suppression chemical
immediately prior to, during and immediately after the activities so as to maintain the entire surface wet;
·
Where a scaffolding is erected
around the perimeter of a building under construction, effective dust screens, sheeting or netting should be provided to enclose the scaffolding from the ground floor level of the building, or
a canopy should be provided from the first floor level up to the highest level
of the scaffolding;
·
Any skip hoist for material
transport should be totally enclosed by impervious sheeting; and
·
Exposed
earth should be properly treated by compaction, turfing, hydroseeding,
vegetation planting or sealing with latex, vinyl, bitumen, shortcrete or other
suitable surface stabiliser within six months after the last construction
activity on the construction site or part of the construction site where the exposed
earth lies.
16.4.2.3
For the barging facilities
proposed at the site compound, the following good site practice is required:
·
All
road surfaces within the barging facilities should be paved,
·
Vehicles
should pass through designated wheel wash facilities, and
·
Continuous
water spray should be installed at the loading point.
16.4.2.4 The above requirements should be incorporated into the Contract Specification for the civil work. In addition, an audit and monitoring programme during the construction phase should be implemented by the Contractor to ensure that the construction dust impacts are controlled to within the HKAQO.
16.4.2.5
No exceedances of the
relevant AQOs are predicted at all representative ASRs during operational phase
and cumulative air quality impact or adverse residual air quality impact is not
anticipated. Mitigation measures for
operational phase are not necessary.
16.4.3 Measures Adopted to Mitigate Noise Impacts
16.4.3.1 For construction phase, the extent of temporary works areas where construction plant would be operated has been reduced to minimize the airborne construction noise impacts as far as practicable. However, unmitigated construction noise would exceed the daytime noise criteria, and therefore, mitigation measures are therefore required. The following mitigation measures have been considered:
·
Good
site practices to limit noise emissions at the source,
·
Use
of quiet plant and working methods,
·
Use
of site hoarding as noise barrier to screen noise at ground level of NSRs,
·
Use
of shrouds/temporary noise barriers to screen noise from relatively static
PMEs,
·
Scheduling
of construction works outside school examination periods in critical area, and
·
Alternative
use of plant items within one worksite, wherever practicable.
16.4.3.2 However, as predicted mitigated noise levels and predicted cumulative noise impacts exceed the noise criterion for Planned Primary School & Secondary School near Wan Po Road during examination period, the contractor should further confirm the construction program of this NSR at the commencement of the CBL construction and reschedule the construction work outside the examination period as far as possible.
16.4.3.3 For the operational phase, partial enclosures along Road D9 and application of low noise surfacing material along CBL and Road D9 have been proposed as noise impacts are contributed by CBL and Road D9.
16.4.4 Measures Adopted to Mitigate Sediment Quality Impacts
16.4.4.1 It is estimated that a total of approximately 4,300m3 marine deposit is required to be excavated from the pile casings. Amongst the excavated volume, approximately 97% is Category L sediment (Type 1 open sea disposal). Category Mp (Type 1 open sea disposal at dedicated sites), Mf (Type 2 confined marine disposal), and H (Type 2 confined marine disposal) sediments contribute to about 3% of the total volume.
16.4.5 Measures Adopted to Mitigate Water Quality Impacts
16.4.5.1 During construction phase, pile excavation should be undertaken in such a manner as to minimise resuspension of sediments. Standard good practice measures should therefore be implemented including the following requirements:
·
All
pile excavation works shall be conducted within a cage type silt curtain;
·
Floating
single silt curtain shall be employed for all marine works;
·
Mechanical
grabs (with a size of 5m3) shall be designed and maintained to avoid spillage
and should seal tightly while being lifted;
·
Barges
and hoppers shall have tight fitting seals to their bottom openings to prevent
leakage of material;
·
Any
pipe leakages shall be repaired quickly. Plant should not be operated with
leaking pipes;
·
Loading
of barges and hoppers shall be controlled to prevent splashing of dredged
material to the surrounding water. Barges or hoppers shall not be filled to a
level which will cause overflow of materials or pollution of water during
loading or transportation;
·
Excess
material shall be cleaned from the decks and exposed fittings of barges and
hopper dredgers before the vessel is moved;
·
Adequate
freeboard shall be maintained on barges to reduce the likelihood of decks being
washed by wave action;
·
All
vessels shall be sized such that adequate clearance is maintained between
vessels and the sea bed at all states of the tide to ensure that undue
turbidity is not generated by turbulence from vessel movement or propeller
wash; and
·
The
works shall not cause foam, oil, grease, litter or other objectionable matter
to be present in the water within and adjacent to the works site.
16.4.5.2 In accordance with the Practice Note for Professional Persons on Construction Site Drainage, Environmental Protection Department, 1994 (ProPECC PN 1/94), construction phase mitigation measures, where appropriate, should include the following:
·
The
design of efficient silt removal facilities should be based on the guidelines
in Appendix A1 of ProPECC PN 1/94. The detailed design of the sand/silt traps
should be undertaken by the contractor prior to the commencement of
construction.
·
Open
stockpiles of construction materials (for example, aggregates, sand and fill
material) of more than 50m3 should be covered with tarpaulin or similar fabric
during rainstorms. Measures should be
taken to prevent the washing away of construction materials, soil, silt or
debris into any marine water bodies.
·
All
vehicles and plant should be cleaned before leaving a construction site to
ensure no earth, mud, debris and the like is deposited by them on roads. An adequately designed and sited wheel
washing facilities should be provided at every construction site exit where
practicable. Wash-water should have sand
and silt settled out and removed at least on a weekly basis to ensure the
continued efficiency of the process. The
section of access road leading to, and exiting from, the wheel-wash bay to the
public road should be paved with sufficient backfall toward the wheel-wash bay
to prevent vehicle tracking of soil and silty water to public roads and drains.
·
Construction
solid waste, debris and rubbish on site should be collected, handled and
disposed of properly to avoid water quality impacts.
·
All
fuel tanks and storage areas should be provided with locks and sited on sealed
areas, within bunds of a capacity equal to 110% of the storage capacity of the
largest tank to prevent spilled fuel oils from reaching water sensitive
receivers nearby.
·
Regular
environmental audit on the construction site should be carried out in order to
prevent any malpractices. Notices should
be posted at conspicuous locations to remind the workers not to discharge any
sewage or wastewater into the meander, wetlands and fish ponds.
16.4.5.3
Regarding sewage from
workforce, portable chemical toilets and sewage holding tanks should be
provided for handling the construction sewage generated by the workforce. A licensed contractor should be employed to
provide appropriate and adequate portable toilets and be responsible for
appropriate disposal and maintenance.
Notices should be posted at conspicuous locations to remind the workers
not to discharge any sewage or wastewater into the nearby environment during
the construction phase of the Project.
Regular environmental audit on the construction site should be conducted
in order to provide an effective control of any malpractices and achieve
continual improvement of environmental performance on site.
16.4.5.4
During operational phase,
proper drainage systems with silt traps and oil interceptors should be
installed, maintained and cleaned at regular intervals as a precautionary
measure to mitigate potential runoff from road surfaces.
16.4.6 Measures Adopted to Mitigate Impacts on Waste Management
16.4.6.1 The amount of C&D material that would need to be transported off site has been minimized as far as practicable in the design. The Project Proponent will ensure all the mitigation measures mentioned in the C&DMMP will be complied with. Wherever practicable, C&D materials should be segregated from other wastes to avoid contamination and ensure acceptability at public filling areas or reclamation sites. Good site practices have also been recommended for chemical waste, general refuse and disposal of chemical waste will follow the relevant ordinances.
16.4.6.2 Prior to the commencement of the construction works, the contractors should incorporate recommendations into a Waste Management Plan to provide an overall framework for waste management and reduction.
16.4.6.3 It is not anticipated that large quantities of waste would be generated during the operational phase. Only a small amount of general refuse would be generated from the footpath and cycle track along CBL and Road D9. Waste collection bins and recycling bins would be provided.
16.4.7 Measures Adopted to Mitigate Marine Ecology and Fisheries Impacts
16.4.7.1
Besides the adoption of
larger span piers to minimize impacts on marine ecology and fisheries
resources, good site practices and site runoff control measures would be
sufficient to protect water quality. The
integrity and effectiveness of all silt curtains should be regularly
inspected. Effluent monitoring should be
incorporated to make sure that the discharged effluent from construction sites
meets the relevant effluent discharge guidelines. For works on land, standard site runoff control measures will be
established and strictly enforced to ensure that discharge of contaminated or
silt-laden runoff into marine waters is minimised.
16.4.7.2
The water quality programme
could also serve the purposes to protect the marine communities inside Junk
Bay. No species ecological or fisheries monitoring programme is needed.
16.4.8 Measures Adopted to Mitigate Landscape and Visual Impacts
16.4.8.1 The proposed landscape and visual mitigation measures for the CBL during construction and operation phase are listed below. Generally, all mitigation measures are to be implemented as early as possible and many of these mitigation measures perform multiple functions.
Construction Phase Mitigation
Measures
|
·
The construction area and contractor’s temporary works areas should
be minimised to avoid impacts on adjacent landscape. |
|
·
Reduction of construction period to practical minimum. |
|
·
Topsoil, where identified, should be stripped and stored for re-use
in the construction of the soft landscape works, where the soil material
meets acceptable criteria and where practical. The Contract Specification
shall include storage and reuse of topsoil as appropriate. |
|
·
Existing trees on boundary of the Project Area shall be carefully
protected during construction. Detailed Tree Protection Specification shall
be provided in the Contract Specification. Under this specification, the
Contractor shall be required to submit, for approval, a detailed working
method statement for the protection of trees prior to undertaking any works
adjacent to all retained trees, including trees in contractor’s works areas.
(Tree protection measures will be detailed at Tree Removal Application
stage). |
|
·
Trees unavoidably affected by the works shall be transplanted where
practical. Trees should be transplanted straight to their final receptor site
and not held in a temporary nursery. A detailed Tree Transplanting
Specification shall be provided in the Contract Specification, if applicable.
Sufficient time for necessary tree root and crown preparation periods shall
be allowed in the project programme. |
|
·
Advance screen planting to proposed roads and associated structures. |
|
·
Hydroseeding or sheeting of soil stockpiles with visually unobtrusive
material (in earth tone). |
|
·
Screening of construction works by hoardings/noise barriers around
works area in visually unobtrusive colours, to screen Works. |
|
·
Control night-time lighting and glare by hooding all lights. |
|
·
Ensure no run-off into water body adjacent to the Project Area. |
|
·
Avoidance of excessive height and bulk of buildings and structures |
Operation Phase Mitigation
Measures for Cross Bay Link
|
·
Compensatory tree planting for all felled trees shall be provided to
the satisfaction of relevant Government departments. Required numbers and
locations of compensatory trees shall be determined and agreed separately
with Government during the Tree Felling Application process under ETWBTC
3/2006. |
|
·
A continuous belt of screen planting along the roads. Planting of the
belt of trees shall be carried out as advance works ahead of other site
formation and building works. |
|
·
Maximise soft landscape of the site, Where space permits, roadside
berms /slope treatment works should be created. |
|
·
During detailed design, refine structure layout to create a planting
strips along the roads to enhance greenery. |
|
·
Use appropriate (visually unobtrusive and non-reflective) building
structural materials and colours, and aesthetic design in built structures. |
|
·
Streetscape elements (e.g. paving, signage, street furniture, railing
etc.) shall be sensitively designed in a manner that responds to the local
context, and minimises potential negative landscape and visual impacts.
Lighting units should be directional and minimise unnecessary light spill. |
|
·
Avoidance of excessive height and bulk of buildings and structures. |
16.4.9 Measures Adopted to Mitigate Landfill Gas Impacts
16.4.9.1 General advice and recommendations for avoidance of environmental impacts related to LFG during construction and operational phases have been addressed. Where applicable, specific measures for handling the hazards identified during the construction and operational phases should be addressed to further reduce the likelihood of incidents and increase the level of safety to the workers and the public. These measures should be reviewed taking into account of the findings of the detailed Qualitative LFG Hazards Assessment (QLFGHA) to be undertaken by the project proponent (Refer to Section 14.7.12).
16.4.9.2 All contractors participating in the works should be aware that methane and carbon dioxide are always likely to be present in the soil and rock voids and all works should be undertaken on the basis of an “assumed presence of LFG”.
16.4.9.3 The precautionary measures outlined in Paragraphs 8.3 to 8.49 and the monitoring requirements and procedures specified in Paragraphs 8.23 to 8.28 of EPD’s Landfill Gas Hazard Assessment Guidance Note should be adopted.
16.4.9.4 Depending on the results of measurements, the actions in the event of LFG being detected in excavations as presented in Table 14.6 should be implemented as a minimum. In order to ensure that evacuation procedures are implemented in the event of the trigger levels, it is recommended that a person, such as the Safety Officer, is nominated, with deputies, to be responsible for dealing with any emergency which may occur due to LFG.
16.4.9.5 General recommended precautionary and protection measures during the design stage should be adopted. For example, as the risk category at the proposed CBL development ranged from low to medium, “some precautionary measures” to “engineering measures required” should be applied by the project proponent to protect the proposed development. To avoid engineering measures, underground rooms or void should be avoided in the CBL development as far as practicable.
16.4.9.6 General recommended precautionary and protection measures during the operational phase should also be adopted such as inspection or maintenance of the utilities services at the area within the 250m Consultation Zone, maintenance workers should assume presence of landfill gas at all times and utility companies should undertake a LFG surveillance exercise at the utility manholes/inspection chambers.
16.4.9.7 Existing monitoring of wells will continue to be monitored by EPDs Landfill Restoration Contractors as part of the restoration contract for TKOL-II/III and to protect site workers and future owners within the 250m Consultation Zone, it is recommended that monitoring of any LFG which may be migrated to the site should be undertaken during the construction on CBL infrastructure when the works involve confined spaces.
16.4.10 Environmental Monitoring and Auditing
16.4.10.1 In addition to the mitigation measures as described above (see more details in the Environmental Mitigation Implementation Schedule within the EM&A Manual), a comprehensive environmental monitoring and auditing programme would be implemented to cover various aspects of concern. An independent environmental checker would also be employed to ensure that all the necessary mitigation measures are implemented in a timely and orderly manner.
16.4.11.1 Mitigation measures and good site practices to minimize the environmental impacts were recommended throughout the impact assessments of air quality, noise, sediment quality, water quality, waste management, marine ecology, fisheries, landscape and visual, and landfill gas. As the Marine Archaeological Investigation did not locate any cultural heritage resources and the diver survey indicated that in many areas the seabed had been disturbed by previous construction work, no further action or mitigation is required for cultural heritage impacts. Recommended mitigation measures were consolidated in the Implementation Schedule which specifies the responsibility, methodology and timing of implementation, such that effective and appropriate implementation of the measures can be assured.