1.1.1
Silver
Mine Bay is a popular bathing beach in Mui Wo, Lantau that attracted 4,550
visitors on a peak day and over 69,000 visitors utilized the beach in 2012.
During holidays, people enjoy cycling around Mui Wo for sightseeing. They
travel between Mui Wo Center and the beach via Wang Tong River Bridge. As the bridge is only about 1.5m
wide, overcrowding problem occurs and pedestrians and cyclists are often
crossing the bridge shoulder to shoulder.
1.1.2
In
order to relieve road safety concern of Wang Tong Bridge (hereafter called “Old
Bridge”), a replacement bridge is proposed to replace the Old Bridge. The
Project Profile and EIA Brief were prepared based on a single replacement
bridge. In the course of the EIA Study, a twin bridge proposal consists of a
new pedestrian bridge and a new cycle bridge (hereafter called “New Bridge”)
are also designed to align with the future amenity development on the northern
side of the Old Bridge. The location of the project site is shown in Figure 1.
1.1.3
This
Project mainly comprises the following works:
i.
Construction of a new cycle bridge next to the
existing bridge
ii.
Demolition of the existing bridge
iii.
Construction of a new footbridge on the same
site of the existing bridge
1.1.4
The
Project consists of the following designated projects under Part I, Schedule 2
of the Environmental Impact Assessment Ordinance (EIAO):
·
Item C.12 – (a)…a dredging operation which is
less than 500m from the nearest boundary of an existing… (iii) bathing beach…
1.1.5
A
project profile (PP-478/2013) has been submitted to Environmental Protection
Department in 28 January 2013 and a study brief (ESB- 256/2013) has been issued
to HyD in March 2013.
1.1.6
As
an environmental impact assessment (EIA) is required under the Environmental
Impact Assessment Ordinance (EIAO), HyD
appointed the Joint Venture of Maurice Lee and Associates Ltd. and Cinotech
Consultants Ltd. (hereinafter called the JV) to perform the EIA study accordingly.
1.1.7
This Executive Summary summarizes the key findings in the EIA Report,
including design selection, identification of sensitive receivers, assessment
and evaluation of environmental impacts during construction and operational
phases, recommendations on mitigation of major impacts, degree of residual
impact and overall conclusion.
2.2.1
Three
bridge design schemes have been considered in the EIA Report.
·
Option 1: A single bridge with two intermediate
piers below high water mark (design in the project profile PP-478/2013);
·
Option 2: A single truss bridge with no
intermediate piers; and
·
Option 3: Twin bridges with one intermediate
pier each above high water mark.
2.2.2
The
twin bridges scheme (Option 3) is the preferred scheme in design and adopted in the EIA Report. This
design comprises two
separated bridges with intermediate supports above high water mark. This design is beneficial in terms
of the following aspects:
Environmental Aspects
·
No permanent damage on riverbed or obstruction
of river flow. In addition, river flow would be improved in operational
phase (vs two piers below high water mark in Option 1);
·
Fewer trees will be affected during construction
(vs larger works area for site formation required in Option 1); and
·
Lower landscape and visual impact by having low
profile and design that matches with surrounding rural environment (vs bulky
design in Option 2).
Engineering
Aspects
·
Complete segregation of pedestrian and cyclist
and thus improving traffic safety and efficiency (vs single bridge with two-way
flow in Option 1); and
·
Sufficient deck height that is capable of
passing 1 in 100 year flooding.
2.3.1
Construction
of New Bridge and demolition of Old Bridge involves the following major
activities:
·
Demolition works;
·
Minipiling;
·
Excavation and backfilling, with some conducted
below high water mark within fully enclosed cofferdam; and
·
Bridge building (formation of bridge structure
and concreting).
2.3.2
To
minimize the number of concurrent activities, construction and demolition works
will be carried out separately in the following order:
(1)
Construction of New Cycle Bridge
(2)
Demolition of Old Bridge
(3)
Construction of New Pedestrian Bridge
2.3.3
The
construction work is expected to last for two years from mid-2017 to mid-2019. No project
that involves heavy construction activity is known to be carried out
concurrently with the construction work of this Project.
3.1.1
Silvermine Beach Resort and village house
located at 1 Tung Wan Tau Road are the most affected air sensitive receivers
within 500m study boundary.
3.1.2
The main source of
construction phase air quality impacts come from dust generated from site
clearance, excavation, foundation and site formation works. To avoid cumulative dust impacts, construction of Cycle/Pedestrian
Bridges and demolition of Old Bridge will be carried out in different phases through adoption of a longer work programme. Given
the small work site and localized work area, the use of standard dust suppression measures and good
site practices are considered sufficient to minimize dust impact on nearby air sensitive receivers. With these mitigation measures in places, no
unacceptable air quality impact in construction phase is expected.
Nevertheless, dust monitoring and audit programme has been recommended in construction phase to ensure
that air quality impact is within acceptable level.
3.1.3
Since
the proposed bridges are designed for pedestrians and cyclists instead of
motorized vehicle, no traffic emission is expected during operation. Therefore,
no air pollutants listed under the Air Quality Objectives will be generated during the operational phase of the Project.
3.2.1
Village house located at 1 Tung Wan Tau Road
is the most affected noise sensitive receiver (NSR)
within 300m study boundary.
3.2.2
The main source of construction phase noise impact
comes from operation of powered mechanical equipment. Typical construction
method, sequence of work and the plant inventory were examined in the EIA Study.
3.2.3
With the implementation of standard noise
mitigation practices including the use of quality plants, use of mobile
noise barriers, and adoption of good site practice, construction noise during non-restricted hours at the representative NSR
is predicted to be well within the assessment criterion.
Table 3.1 Summary
of Mitigated Construction Noise
|
NSR
|
Description
|
Land Use
|
Predicted Maximum Noise Level from the Project, dB(A)
|
Noise Criteria, dB(A)
|
Exceedance, dB(A)
|
|
NSR1
|
1 Tung Wan Tau Road
|
Village
|
72
|
75
|
-
|
3.2.4
As no fixed plant will be installed and operated
in operational phase, no operational noise impact is anticipated.
3.3.1
Water sensitive receivers most likely to be affected by the
Project within the 500m study boundary include Wang Tong River, Silver Mine Bay Beach and
Silver Mine Bay.
3.3.2
The main source of water quality impacts arising from
construction activities are release of suspended solids during excavation and falling
of debris into water during demolition of Old Bridge and construction of New
Bridge. These will be minimized by carrying out excavating activities within
fully enclosed cofferdam and provision of solid working platform with toe board
below work site. The cofferdam will be implemented in a way that will not affect the
water flow in Wang
Tong River during construction.
3.3.3
Site runoff from exposed soil, earthworks and
stockpiles during rainstorms and sewage generated from construction workforce
will be minimized by implementing appropriate mitigation measures and good site
management practices, such as covering by impermeable sheeting and provision
and regular maintenance of chemical toilet. With the implementation of these mitigation
measures, no unacceptable water quality impact is expected.
3.3.4
No
operational phase water quality impact is expected from the New
Bridge.
3.4.1
Waste arising during
construction shall
be handled and disposed of properly to prevent causing damage to the
environment. During construction phase, major construction
& demolition (C&D) materials will mainly be broken concrete and metal bar from
demolition of Old Bridge, excavated materials and marine sediment generated from piling works.
Inert C&D materials will be reused onsite as far as possible for
backfilling. Excess portion will be disposed at public fill reception
facilities. Non-inert ones will be recycled or disposed at landfill. Marine
sediment extracted from minipiles will be treated by cement solidification and
backfilled on land. Alternatively, the
solidified sediment shall be delivered to public fill reception facilities
for beneficial reuse as the last resort.
3.4.2
Other
wastes include chemical waste from maintenance of plant equipment and general
refuse from workforce. They will be collected, stored and disposed of properly.
With implementation of the recommended measures and site practices, no
unacceptable impact due to waste management is expected.
3.4.3
No
waste generation activity is expected during the operational phase.
3.4.4
Based
on historical aerial photos, site visit and government record, land uses nearby Wang Tong River Bridge have been
and remain as residential (village), agricultural,
tourism and/or recreational uses. No industrial activity was identified and hence land contamination at the Site is not
expected.
3.5.1
While some flora
and fauna which are of conservation importance are identified within 500m from
the Project boundary, none of which are within the Project Site. The areas
within the Project site that will be affected directly during construction
include a small area of Sandy Shore, Developed Area and Wang Tong River and all of which are of low or low to moderate
ecological value (as summarized in Table
3.2 below). The ecological impact during construction is therefore minor
and acceptable.
Table
3.2 Summary of Habitat Loss
|
Habitats
|
Ecological
Value
|
Directly Impacted Area (m2)
|
|
Permanent
|
Temporary
|
Total
|
|
Watercourse
– Wang Tong River
|
Low
- Moderate
|
-
|
91
|
91
|
|
Developed
Area
|
Low
|
-
|
204
|
204
|
|
Sandy
Shore
|
Low
|
226
|
676
|
902
|
|
Total
|
226
|
971
|
1197
|
3.5.2
With
proper implementation of mitigation measures during construction, adverse residual impact is not expected. The overall
impact on terrestrial and aquatic ecology is acceptable.
3.6.1
The proposed development will generate some landscape and visual
impacts. However,
there are opportunities, during the project’s design,
construction and operation stages, for incorporating mitigation measures which
will contribute to reducing landscape and visual impacts to acceptable levels.
These include designing and implementing new bridges which are sensitively
integrated into the existing environment and protecting trees in construction
phase.
3.6.2
Figure 2 shows that the views of Wang Tong
River Bridge from Chung Hau and Silvermine Bay Beach after realization of
proposed mitigation measures in Year 10 of operation. None of the landscape
resources, landscape character areas or visually sensitive receivers will
experience adverse residual impacts following
mitigation during the operation phase. The overall residual landscape and visual
impacts of the proposed development are acceptable with mitigation during the
construction and operation phases.
3.7.1
Environmental
monitoring and audit requirements have been identified and recommended to
ensure the effectiveness of the recommended mitigation measures. These
requirements are specified in the EM&A
Manual and cover the area of air quality (dust), noise, water quality,
ecology, landscape and visual and waste management. Regular site audits throughout the construction of
the Project have also been recommended.