The
location and alignment of the Project components are shown in Figure
3.1 to 3.5. The scope of the
Project comprises:
·
Improvement
of an approximately 4.5km long section of Shenzhen River;
·
Re-provision
of a boundary patrol road and about 4.5km of boundary
fence;
·
Dry
weather flow interception along Shenzhen side of the river; and
·
Associated
landscaping works.
3.2.1
River
Modification Works
The proposed
river modification works under the Project are summarized in Table 3.1. The work areas of the Project are shown in Figure
3.6.
Table 3.1 River
Improvement Works
|
Works Area |
Section |
Chainage |
Length (m) |
Works Descriptions |
|
I |
Liantang BCP |
16+458 to 17+930 |
1,472 |
River widening; embankment works;
boundary patrol road and boundary fence construction; sewage diversion |
|
II |
Heung Yuen Wai
BCP |
15+458 to 16+458 |
1,000 |
River widening; embankment works; boundary
patrol road and boundary fence construction; sewage diversion |
|
III |
Luo Fang Bridge to Flood Retardation Pond |
14+463 to 15+458 |
995 |
River widening; embankment works;
boundary patrol road and boundary fence construction; sewage diversion; flood retardation
pond construction. |
|
IV |
Luo Fang Bridge and downstream |
13+465 to 14+463 |
998 |
River widening; embankment works;
boundary patrol road and boundary fence construction; sewage diversion; Luo
Fang Bridge and Police Kiosk reconstruction. |
Under the
proposed Stage 4 regulation, about 4.5km section of the Shenzhen River will be
regulated. The work starts from the
confluence with Ping Yuen River (ie the endpoint of Stage
3 regulation works) and will pass through the Luo
Fang Sewage Treatment Works, Luo Fang Bridge, Luo Fang Village, Sai Ling
Village in Shenzhen and Kaw Liu Village and Chuk Yuen
Village in Hong Kong, and ending near Pak Fu Shan in Hong Kong.
The design
principle of the works is to protect the livelihood of residents on both sides
of the river with an ecological sensible design, which should maintain the
naturalness of the river and riparian habitats and hence protect the
biodiversity. As shown in Figures
3.1 to 3.5, the design alignment
will follow the existing watercourse as far as possible to minimise alternation
to the existing river profile and meandering nature, minimise landtake and avoid massive excavation and filling. Moreover, the river bed will remain as
natural bottom without concreting. At
several meandering locations with sharp bend, a floodplain will be created with
the planting of existing species to resemble the naturalness of the river while
achieving the required flood design standard.
Trapezoid channel design
will be used in most of the river regulation works. The bottom width will be in a range of 14 to
16m and will be increased to 30m when approaching the downstream outlet. The top width of these river sections will be
limited to 60m and the slope of sidewalls at Shenzhen side and Hong Kong side
will be in range of 1:2 to 1:3 and 1:2.5 to 1:3, respectively. The area at the top of embankment will be
used as boundary patrol road and maintenance services berm.
Typical trapezoid channel is shown in Figure
3.7.
Compound channel design
will be used to suit actual site conditions.
The design will be harmonized with the existing natural environment with
an aim to minimize the disturbance of ecological habitats. Different features like flood channel and
marshland areas will be incorporated into different sections of the river in
order to resemble the existing river condition.
The height of the sidewall will be about 1 to 2m and the slope of the sidewall
will be in the range of 1:3 to 1:5. Typical section of compound channel is
shown in Figure
3.8.
Vertical sidewall should be
adopted in area where further modification is limited by site constraint
especially those in the Shenzhen side where land for trapezoidal channel is not
available. It is estimated that about
240m of the river will be regulated into vertical channel with 4 to 5 m high
vertical sidewall. The top width of the
sidewall will be about 1m. Typical river section design with vertical sidewall
is shown in Figure
3.9.
The proposed
flood retardation pond will be located at chainage
14+778 to 15+183 on the Shenzhen side covering an area of 22,000 m2
with a storage capacity of 80,000 m3. Overflow weir will be used at the inlet of
the retardation pond. Water will enter
into the retardation pond when the water level at the inlet is higher than the
weir. Flood water will be discharged
back to the river through control gates when the water level in the river is
lower than that in the retardation pond.
Landscape treatment with design compatible with the surrounding area
will be provided to the flood retardation pond, including the isolated islands
in the pond.
3.2.2
Reprovisioning of Boundary Patrol Road and Boundary
Fence
The reprovisioning
of boundary patrol road and boundary fences along the concerned section of
Shenzhen River under the Stage 4 regulation has already been incorporated into
the design and construction programme of this Project.
Hong Kong Side
The design
of boundary patrol road in Hong Kong side will be based on the Transport Planning and Design Manual and
Guidance Note published by the
Highways Department of HKSAR. The total
length of the boundary patrol road to be reprovided
under this Project is about 4.5km and the width will be 3.5m. The boundary patrol road will be paved with
asphaltic concrete. Passing bays (12m long and 6m wide) will be
provided at 200 to 300m intervals. Boundary
fences will be constructed on
both sides of the boundary patrol road.
The height of secondary and primary boundary fences will be 3.5m and
4.6m respectively and the primary fence will be equipped with security sensing
system and barbed wire. The typical
section drawing of boundary fences and boundary patrol road are shown in Figures
3.10 and 3.11.
The reprovisioning of the
section of boundary patrol road and boundary fence along the section of
Shenzhen River under this Study will be managed by DSD as an “advanced works”
of this Project. Currently,
the Architectural Services Department (ArchSD) is
managing the construction of a secondary boundary fence and reprovision
of boundary patrol road from Pak Hok Chau to Sha Tau Kok.
Shenzhen Side
Dry
weather flow interception will be carried out at the river bank of Shenzhen
side. The existing boundary patrol road
and boundary fence affected by the construction of the new sewer will need to
be demolished and reprovided. In addition, a section of boundary patrol
road and boundary fence will need to be reconstructed due to realignment of the
Shenzhen river near the proposed LT/HYW BCP. A total of about 2,630m of the boundary
patrol road and boundary fence at the Shenzhen side (upstream of Luo Fang Bridge) will be reprovided. The standard width of the new boundary patrol
road and height of the new boundary fence on the Shenzhen side will be 6m and 3.5m, respectively. The boundary patrol road will be paved with
concrete. Table 3.2 summarizes the details of the new boundary patrol road
and boundary fence at the Shenzhen side.
Table 3.2 Reprovisioning of Patrol Road and Boundary
Fence at the Shenzhen Side
|
Chainage |
Length (m) |
Reprovision Rationale |
|
15+300 to 16+180 and 17+162 to 17+930 |
1,648 |
Sewer for dry weather flow interception
works will be laid under the existing patrol road. Open trench method will be
used and boundary fence will
need to be removed during construction. |
|
16+180 to 17+162 |
982 |
The river will be shifted to the east in
order to accommodate the planned LT/HYW BCP.
The boundary patrol road and boundary fence will need to be reprovided
in this section. |
3.2.3
Dry
Weather Flow Interception at Shenzhen Side
Currently, the separation of sewage from stormwater in Shenzhen is not very effective and stormwater
discharge points at Shenzhen side into the
24 overflow manholes will be constructed to collect
the dry weather flow and gravity sewer will be built to convey the dry weather
flow to the Luo Fang Sewage Treatment Works. During the wet season, the rainwater overflow
from the manholes will be discharged into Shenzhen River. The design and construction of the dry
weather flow interception can be divided into two sections which are summarized
in Table 3.3 and shown in Figure
3.12.
Table 3.3 Dry
Weather Flow Interception at the Shenzhen Side
|
Section |
Chainage (Sewerage at Shenzhen
Side) |
Length (m) |
Diameter (mm) |
End Point Connection |
Site Constraints |
|
Project’s end point (upstream) to sewage
tunnel |
JW3+026 to JW1+435 |
1,591 |
1,000 |
Connect to existing sewage tunnel at
JW1+435 |
Most of the sewer will be constructed
underneath the new boundary patrol road |
|
Sewage tunnel to Project’s start point
(downstream) |
JW1+435 to JW0+000 |
1,435 |
1,200 |
Connect to Luo
Fang Sewage Treatment Works at JW0+000 |
Sewer will be constructed underneath the
existing or new boundary patrol road |
3.2.4
Landscaping
Works
The landscaping works along the river embankment,
channel sides and flood retardation pond will be designed to re-establish the
natural riparian ecosystem with the aims to enhance the local biodiversity,
protecting the water resources and avoid erosion. Vegetations chosen for the landscaping works
will be based on the following criteria:
·
Well
adaptive to the environment – mainly use native species supplemented by
suitable exotic plants;
·
Able
to enhance the local biodiversity – mixed vegetations of arbour, groundcovers
and grasses will be placed along the river;
·
Low
management requirements – those species with low management requirements will
be chosen to minimize the maintenance cost; and
·
Prevent
obstruction of sight view - design should fulfil the security requirements for
boundary patrolling and therefore should not obstruct the sight view along the
boundary patrol road.
The landscape characters along the river course will
be designed with considerations of local characteristics and the landuse planning in the adjacent area.
The preliminary proposed landscape treatment along
the sloped river bank can be classified into three types: natural vegetation, semi-natural and artificial. The main materials and functions of each type
of treatment are shown in Table 3.4.
Table 3.4 Common Landscape
Treatment
|
Type of Treatment |
Protection Function |
Ecological Function |
Use of Material |
Cost and Construction |
|
Natural Vegetation |
·
less resistant to water flow; ·
usually used at river sections with lower velocity (1-3m/s) |
·
can retain pollutants; ·
high vegetation cover; ·
can provide better habitats for organisms |
·
use natural soil and natural materials |
·
low cost; simple human maintenance |
|
Semi-natural Vegetation |
·
can resist 4-6m/s water flow; ·
better and more stable revetment in general |
·
can better retain pollutants; ·
use the space between wood log and rock to carry out hydraulic and
provide habitats for organisms; ·
vegetation cover rate not high at the beginning |
·
natural or semi-natural materials; ·
civil engineering materials being high polymer; stable
chemical nature |
·
lower cost; simple human maintenance; easy construction |
|
Artificial |
·
can resist strong water flow; ·
some can resist velocity over 6m/s |
·
can retain pollutants; ·
greening is possible at water with frequent changes |
·
materials include steel and cement elements; ·
strong materials |
·
higher cost; higher standard required for construction |
Detailed landscape design for the Project will be
submitted to the relevant authority for approval during the detailed design
stage.
The
construction phase of the main works will last for 44 months. An advanced works contract on the construction of boundary fence and
boundary patrol road on Hong Kong side will be included as part of this Project
and will last for about 36 months between the period of February 2012 and
January 2015. The
proposed construction programme is presented in Table 3.5 and shown in Figure
3.19.
Table 3.5 Construction
Programme
|
|
Phase |
Date |
Duration |
Works Description |
|
1 |
Advanced Works |
February 2012 to January 2015 |
36 months |
Construction of boundary fence and boundary patrol
road on HK side |
|
2 |
Preparation Phase |
March to July 2013 |
5 months |
Tendering; land resumption |
|
3 |
Pre-construction |
August to September 2013 |
2 months |
Construction of site access roads and site office,
site clearance, site preparation works etc. |
|
4 |
Construction |
October 2013 to December 2016 |
39 months |
Main construction works of the Project such as
dredging of river sediment and soil excavation, construction of flood
retardation pond, boundary fence and boundary patrol road on Shenzhen side,
river modification works, dry weather flow interception works etc. |
|
5 |
Post-construction |
January 2017 to March 2017 |
3 months |
Demolition of temporary structures,
landscaping works etc. |
Temporary river diversion will be carried out, if necessary,
before the commencement of the construction of the regulation works. The main construction works include boundary
patrol road and boundary fence, temporary river diversion, soil excavation,
embankment construction, sewage diversion works and landscaping works.
3.4.1
Advanced
Works - Reprovisioning of Boundary Patrol Road and Boundary
Fences
The reprovisioning of
boundary patrol road and boundary fences under this Project will be coordinated
with ArchSD’s Construction
of a Secondary Boundary Fence and New Sections of Primary Boundary Fence and
Patrol Road contract. The site will
be cleared and excavated or filled to the designed road level with minor earth
retaining work. Reinforced concrete footing
for the fence will be cast in-situ.
Steel fence will then be erected.
The patrol road will be paved with asphaltic concrete.
3.4.2
River
Diversion
Water will be diverted before the commencement of the
soil excavation and construction works.
A longitudinal cofferdam will be built at the central of the designed
river course to meet the design criterion for 5-year design period and will be
kept as “diversion dyke”. The cofferdam
will be made of hessian bags with clay and the surface will be laid with impermeable
membrane. Additional cofferdams will be
built across the river in 200 to 300m intervals of the designed river course to
meet the need of construction. A typical
cross-section showing the river diversion work and the sequence of construction
at the river is shown in Figure
3.13.
When the excavation and placement of embankment
foundation are carried out on one side, the river course on the other side will
be used as diversion channel.
3.4.3
Excavation
Works
As shown in Figure 3.13, after the cofferdam is built and the
inside of the cofferdam is dewatered, excavation will be carried out in dry
condition within the cofferdam. The
river bank will be excavated by backhoes of 2 m3 capacity. The original river bed will be excavated by backhoes
of 1 m3 capacity or long boom backhoe of 0.55 m3 capacity. Once the
excavation of river bed is completed, the cofferdam will be demolished using
the backhoes or long boom backhoe.
The excavated spoils will be transported
by dump trucks and temporarily stored at the stockpiling area within the
Project Site (see Figure 3.14 to Figure
3.17). It is estimated that
about 690,200 m3 of excavated materials will be generated, of which
about 95,000 m3 of excavated soil will be reused on-site. The contaminated river sediments (about
70,000 m3) will be disposed of at the Contaminated Mud Pit at East Sha Chau (Hong Kong) or other
designated mud pit authorised by the CEDD while the surplus excavated soil and
category L sediment will be transferred to Huangmao Dao
(黃茅島)
managed by Shenzhen. Both contaminated
river sediments and surplus excavated soil will be transferred off-site by
truck to Shekou Pier and then loaded to barges for
re-exporting to designated disposal areas.
Subject to the sediment testing results, the quantities of contaminated
river sediments may be refined in later stage.
3.4.4
Embankment
Construction
New dykes on both sides of the river
course will be constructed with the excavated soil from the excavation
works. Wheel loaders with capacity of 2
to 3 m3 will be used for earth moving. 10-tonnes self-unloading trucks, 74-kw
bulldozers and 10-tonness vibrating rollers will be used for materials
transportation, paving and compacting respectively. After excavation of the foundation has been
completed, placement of filling materials will be carried out and the thickness
of each filling layer will be between 300 to 500 mm.
3.4.5
Slope
Protection Works and Construction of Retaining Walls
Geotextile and crushed rocks will be laid on the slope surface of
the river bank after excavation and modification works. No-fines concrete and concrete block will be
placed on the surface. The retaining
walls along the river banks will be constructed by gabion wall or concrete
wall.
3.4.6
Dry
Weather Flow Interception Works at Shenzhen Side
The sewers will be laid by open trench method. Trench support measures will be used for
excavation deeper than 1.2m below existing ground level. All open trenches will be covered as soon as
practical after placement of the sewers.
3.4.7
Landscaping
Works
Landscaping works will be carried out after the
completion of embankment construction and slope protection works. The works will be carried out at suitable
seasons under the supervision of qualified landscape professionals ([1]).
It is revealed in the sediment modelling result that
the amount of sedimentation in the section of Shenzhen River within the Project
Site is minimal, due to the fact that the gradient of the concerned river
section is relatively steep and the river is not affected by tidal
movement. Hence, only small scale
maintenance dredging activity along the river channel is anticipated at regular
intervals (the frequency will be determined through sediment monitoring in the
operation stage), and the scale of maintenance dredging will be very small as
compared with the dredging works during the capital works construction. Maintenance dredging will mainly be conducted
in dry season.
Maintenance dredging of sediment may be required at
the flood retardation pond on Shenzhen side and will be carried out by the
Shenzhen side. The flood retardation
pond will only be used for water storage during severe rainstorm event in the
wet season, and therefore the rate of sediment accumulation in the pond is
expected to be small. As such, and given that the size of the pond is
only about 2.2 ha on plan, the scale and volume of the maintenance dredging, if
required, is anticipated to be significantly smaller than that during the
capital works construction. It is worth
to note that the flood retardation pond is a confined area, any suspended river
sediments associated with dredging will eventually settle within the pond
without causing any sediment release into the river.
It is
noted that the following projects will be carried out concurrently in the
vicinity of the Project Site:
·
LT/HYW BCP and the associated works;
·
Construction of a Secondary Boundary Fence and
New Sections of Primary Boundary Fence and Patrol Road; and
·
Drainage Improvement in Northern New
Territories, Package C (Remaining Works).
There are
two planning studies with study areas within and in the vicinity of the Project
Site:
·
Land Use Planning for the Closed Area; and
·
New Development Areas in North East New
Territories.
The
locations of the concurrent projects and the planning study areas are shown in Figure
3.18.
LT/HYW BCP and the Associated Works
By connecting
with the Eastern Corridor in Shenzhen, the proposed LT/HYW BCP will provide an
efficient access to the eastern part of Guangdong Province. The proposed new BCP will satisfy the
long-term transport needs and help re-distribute the cross-boundary traffic
amongst the crossings in the eastern part of the territory and will alleviate
the frequent traffic congestion at the Man Kam To and
Sha Tau Kok BCPs. The scope of
work of this Project also includes the relocation of Lin Ma Hang Road and resite of Chuk Yuen Village.
It is
anticipated that the construction of the LT/HYW BCP and connecting roads will
commence at the end of 2013 and be completed in end 2018. The planned construction period for the resite
of Chuk Yuen Village is from late 2010 to early 2012
for population intake by early 2013.
Construction of a Secondary Boundary
Fence and New Sections of Primary Boundary Fence and Patrol Road
This
project mainly comprises the construction of a secondary boundary fence (SBF)
along the southern edge of the existing boundary patrol road (BPR)
(approximately 21.7km) from west (Pak Hok Chau) to east (Sha Tau Kok). For sections
where the existing primary boundary fence (PBF) runs along the southern edge of
the BPR, a new fence with sensor alarm system will be constructed on the
northern edge of the BPR as part of the PBF whereas the existing PBF will be
modified to become the SBF. The project
also includes the conversion of the existing maintenance services road along
the Shenzhen River bank to the north of the Lok Ma Chau Loop and Hoo Hok Wai into a new section of the
BPR with a PBF and a SBF; and construction of two new sections of the BPR with
a PBF and a SBF along the Shenzhen River side to the north of Pak Fu Shan and
northwest of Lin Ma Hang Village. In
addition, the Project includes the construction of a checkpoint at the entrance
to the Sha Tau Kok town and
replacement of the existing checkpoint at Pak Hok Chau, removal of the existing checkpoints at Lok Ma Chau, Sha
Ling, Ping Che and Shek
Chung Au, and removal of the existing PBF along those sections of the existing
BPR which will be replaced by new sections of the BPR.
Based on the advice from ArchSD,
the latest tentative construction programme shall be from end 2011 to early
2013 (section from Ng Tung River to Ping Yuen River) and from end 2011 to end
2013 (section from Pak Fu Shan to Lin Ma Hang Road).
Drainage Improvement in Northern New Territories, Package C (Remaining
Works)
The Project comprises the improvement of Ping Yuen
River through construction of 1.9 km of Drainage Channel TKL05 in Ta Kwu Ling. The construction works will mainly involve site clearance, site
preparation, earthworks and other general construction activities. The operation phase works will primarily be
the routine maintenance and operation of the completed drainage channel. The construction work is scheduled to
commence in late 2012 and completed by 2016.
Land Use Planning for the Closed
Area
To formulate the land use framework
to guide future preparation of statutory town plans for the area to be released
from the Closed Area before the completion of the secondary boundary fence,
Planning Department has embarked on a planning study Land Use Planning for the Closed Area (hereafter “the Closed Area
Study”), to carefully examine the development potential and constraints of
these areas.
The Closed Area Study was completed in July 2010 and
the planned land uses along the Project Area include the “Village Type
Development” (“V”), “Recreation” (“REC”) and “Green Belt” (“GB”). Nevertheless, the schedules and programs of
those FCA Study proposals (particularly “V” and “REC”) should be subject to
private initiatives and market-driven factors while the development schedule
and programme of the NENT NDAs Study are still not
available at this stage. Based on the
Recommended Development Plan of the Closed Area Study, it is not anticipated that there will be large-scale developments in the
vicinity of the Project in addition to the development of the LT/HYW BCP.
New Development Areas in North East
New Territories
The North
East New Territories New Development Areas Planning and Engineering Study
(hereafter “the NENT NDAs Study”) formulates the
development plans for the NDAs in Kwu
Tung North, Fanling North and Ping Che / Ta Kwu Ling (PC/TKL). The nearest NDA to the Project Site is PC/TKL
NDA, which is located at more than 600m from Shenzhen River. According to the Preliminary Outline
Development Plan of the NENT NDAs Study, PC/TKL NDA
is planned for accommodating high value-added non-polluting special industries,
the six industries (including testing and certification services, innovation
and technology, cultural and creative industries, environmental industries
etc), port back-up and logistics industries and low to medium density
residential developments. The NENT NDAs Study is in progress and there is no confirmed development schedule and programme yet. As advised by the project proponent of the
NENT NDAs Study, the earliest construction works in
PC/TKL NDA is unlikely to commence before 2017.
As such, it is anticipated that no works in PC/TKL NDA would be
conducted concurrently with the works under this Project.
3.6.1 Cumulative
Environmental Impact
As the above two concurrent projects (LT/HYW
BCP and the Associated Works and Construction of a Secondary Boundary Fence and New
Sections of Primary Boundary Fence and Patrol Road) will have construction works undertaken concurrently
in close proximity to Project Site, there is a potential for cumulative
construction phase impacts, including dust, noise, water quality, waste,
ecology and landscape and visual, which need to be assessed in this EIA.
Of particular to note, the reprovisioning
of boundary patrol road and boundary fences along the concerned section of
Shenzhen River under the Stage 4 regulation has already been incorporated into
the design and construction programme of this Project.
The
Drainage Improvement in Northern New Territories, Package C (Remaining Works)
project is subject to another future detailed EIA Study and detailed
construction programme is not available at this stage. The cumulative impact cannot be assessed at
this stage. However, since the drainage
improvement works is located at about 500m from the Site and given its nature
and scale of works, adverse cumulative impact is not anticipated.
The schedules and programs of those FCA Study
proposals should be subject to private initiatives and market-driven
factors. Hence, it is not possible to
assess the cumulative impact at this stage.