This Section
assesses the potential noise impacts associated with the construction and operation
of the Project.
4.2
Relevant Legislation and
Guidelines
4.2.1
Construction
Noise
The principal legislation relating to the
control of construction noise is the Environmental
Impact Assessment Ordinance (EIAO)
(Cap. 499). The Technical Memorandum on Environmental Impact
Assessment Process (EIAO-TM),
issued under the EIAO, provides
guidelines and noise criteria for evaluating the noise impact.
The Noise
Control Ordinance (Cap. 400) (NCO) also provides means to assess the construction noise impact. Various Technical Memoranda (TMs), which
stipulate control approaches and criteria, have been issued under the NCO. The following TMs are applicable to the
control of noise impact from construction activities:
·
Technical Memorandum on Noise from
Construction Work other than Percussive Piling (GW-TM); and
·
Technical Memorandum on Noise from
Construction Work in Designated Areas (DA-TM).
General Construction Works
Under the EIAO, potential noise impact arising from general construction
works during normal working hours (ie 07:00 to 19:00 hrs on any day not being a
Sunday or public holiday) at 1 m from the external façade of the uses, which
rely on opened windows for ventilation, is to be assessed in accordance with
the noise criteria specified in the EIAO-TM. The EIAO-TM
noise standards are presented in Table
4.2a.
Table 4.2a EIAO-TM
Day-time Construction Noise Standards (Leq, 30 min dB(A))
|
Use |
Noise Standard (dB(A)) |
|
Domestic Premises |
75 |
|
Educational Institutions (normal periods) Educational Institutions (during examination periods) |
70 65 |
|
Notes: (1) The above standards apply to uses which
reply on opened windows for ventilation. (2) The above standards shall be viewed as
the maximum permissible noise levels assessed at 1m from the external façade. |
|
When assessing a Construction Noise Permit
(CNP) application for the use of Powered Mechanical Equipment (PME) during the restricted
hours, the Noise Control Authority will compare the Acceptable Noise Levels
(ANLs), as promulgated in GW-TM, and the Corrected Noise Levels (CNLs)
(ie after accounting for factors such as barrier effects and reflections)
associated with the proposed PME operations. The ANLs are obtained with corrections
for the duration of the CNP and multiple permit situations, if applicable, to
the Basic Noise Levels (BNLs). The
BNLs are related to the noise sensitivity of the area in question and different
Area Sensitivity Ratings (ASR) have been established to reflect the background
characteristics of different areas.
The appropriate ASR for the Noise Sensitive Receiver (NSR) is determined
with reference to Table 4.2b.
Table 4.2b Area
Sensitivity Ratings
|
Types of Area Containing NSR |
Degree to which NSR is affected by
Influencing Factor (IF) |
||
|
|
Not Affected |
Indirectly
Affected |
Directly
Affected |
|
Rural area, including |
A |
B |
B |
|
Low density residential area consisting of low-rise or isolated
high-rise developments |
A |
B |
C |
|
Urban area |
B |
C |
C |
|
Area other than those
above |
B |
B |
C |
|
Notes: The
following definitions apply: (a) " (b)
"directly
affected" means that the NSR is at such a location that noise generated
by the IF is readily noticeable at the NSR and is a dominant feature of the noise
climate of the NSR; (c) "indirectly affected" means that the NSR is at
such a location that noise generated by the IF, whilst noticeable at the NSR,
is not a dominant feature of the noise climate of the NSR; (d) "not affected" means that the NSR is at such a
location that noise generated by the IF is not noticeable at the NSR; and (e)
"urban
area" means an area of high density, diverse development including a
mixture of such elements as industrial activities, major trade or commercial
activities and residential premises. |
|||
The relevant BNLs are shown in Table 4.2c.
Table 4.2c Basic Noise
Levels for General Construction Works (BNL, Leq, 5 min dB(A))
|
Time period |
Area Sensitivity Rating (dB(A)) |
||
|
|
A |
B |
C |
|
All days
during the evening (ie 19:00-23:00 hrs) and general holidays (including
Sundays) during the day and evening (ie 07:00-23:00 hrs) |
60 |
65 |
70 |
|
All days during the night-time (ie 23:00-07:00
hrs) |
45 |
50 |
55 |
The Noise Control Authority will consider
a well-justified CNP application, for construction works within restricted
hours as guided by the relevant TMs issued under the NCO. The Noise Control Authority will take into
account adjoining land uses and any previous complaints against construction
activities at the site before making a decision. Nothing in this EIA Report shall
bind the Noise Control Authority in making its decision. The Noise Control Authority may include
any conditions in a CNP that it considers appropriate. Failure to comply with any such
conditions may lead to cancellation of the CNP and prosecution action under the
NCO.
4.2.2
Operational
Road Traffic Noise
The traffic noise standards for planning
purposes specified in Table 1 under Annex 5 of the EIAO-TM were employed as the noise limits for the road traffic
noise impact assessment. The
applicable road traffic noise standards are presented in Table 4.2d.
Table
4.2d
|
Use |
Noise Standard (dB(A)) |
|
Domestic Premises |
70 |
|
Educational Institutions |
65 |
|
Hospitals and Homes for the Aged |
55 |
|
Notes: (1)
The
above standards apply to uses which reply on opened windows for ventilation. (2)
The
above standards shall be viewed as the maximum permissible noise levels
assessed at 1m from the external façade. |
|
For
traffic noise assessment, the major roads within 300 m of the Project boundary
have been included in the assessment.
The traffic noise impact is considered
significant if the traffic noise level at the Noise
Sensitive Receivers (NSRs) with
the road project is greater than that without the road project at the design
year by 1.0 dB(A) or more.
The
noise level due to the traffic on the Project should not exceed the criteria as
presented in Table 4.2d by 1.0 dB(A).
In
the case where noise prediction results show NSRs still exposed to noise levels
exceeding the relevant noise criteria after the implementation of all direct
mitigation measures, the total number of existing dwellings, classrooms and
other noise sensitive elements which may qualify for indirect technical
remedies, the associated costs and any implications for such implementation
should be identified and estimated.
The eligibility of the affected premises for indirect technical remedies
will be determined with reference to the following three criteria:
·
The predicted overall noise level at the
NSR from the Project together with other traffic noise in the vicinity must be
above the noise criteria presented in Table
4.2d;
·
The predicted overall noise level at the NSR
is at least 1.0 dB(A) more than the prevailing traffic noise level, ie, the
total traffic noise level existing before the works to construct the road were
commenced; and
·
The contribution from the Project to the increase in
predicted overall noise level at the NSR must be at least 1.0 dB(A).
4.3
Baseline Environmental
Conditions and Noise Sensitive Receivers
4.3.1
Baseline Environmental Conditions
The Study Area is
generally rural in nature, with the surrounding land comprising scattered village
houses, school, hospital, home of the aged, new high-rise residential
developments, and unoccupied open spaces. In accordance with the Outline
Zoning Plans (OZP) for Yuen Long (No.S/YL/17), Nam Sang Wai (No.S/YL-NSW/8) and
Tai Tong (No.S/YL-TT/14), the land uses of the surrounding areas were zoned as
“Open Space” (O), “Government/Institution/Community” (GIC), “Comprehensive
Development Area” (CDA), “Village Type Development” (V), “Undetermined” (U) and
“Agriculture” (AGR) (Figures 4.3a to
4.3c).
The
environment of the Study Area is already subject to a high level road traffic
noise. The existing traffic noise sources are mainly the traffic on the
Yuen Long Highway, Pok Oi Roundabout and
4.3.2
Noise
Sensitive Receivers
In accordance with the requirements stated
in Section 3.4.1.2 of the EIA Study Brief,
the Study Area for the noise impact assessment covered a distance of 300m from
the boundary of the Project. Only
the first layer of the NSRs located along Yuen Long Highway were included in
the assessment as the NSRs behind were located further away from the road and
were screened. The area considered
in the assessment is shown in Figure 4.3d.
The selected existing representative NSRs
that may potentially be affected by the construction and operation of the
Project include Wong Uk Tsuen, Small Traders New Village, Chuk San Tsuen,
Hoover Garden and village houses along Yuen Long Highway, the high-rise residential
development at YOHO Town, Kwong Ming Ying Loi School (an educational
institution), and Jockey Club Care and Attention Home (a home for the
aged).
In accordance with the OZPs for Yuen Long,
Nam San Wai and Tai Tong referenced above, the areas immediately east of the
Yuen Long Highway are zoned as “Undetermined”
(U) and “Agriculture” (AGR), the areas immediately to the west of the Yuen Long
Highway are zoned as “Open Space” (O), “Government/Institution/Community”
(GIC), “Comprehensive Development Area” (CDA) and “Village Type Development”
(V).
Site visits to Pok
Oi Hospital and Jockey Club Care and Attention Home were carried out on 18
January 2008. According to the
management of Pok Oi Hospital, central air-conditioning system was provided to
the hospital and there was no staff quarters within the hospital. Pok Oi Hospital therefore does not rely
on openable windows for ventilation as shown in the written confirmation from
the Hospital in Annex C1. As observed during the site visit and
confirmed by the floor plans provided by the management of Jockey Club Care and
Attention Home, the rooms facing Yuen Long Highway were bedrooms and therapy
rooms installed with window-type air-conditioners and openable windows. Some of the windows were found to be
opened during the site visit. As a result, Pok Oi Hospital was not identified
as NSR, but the Jockey Club Care and Attention Home was identified as NSR.
Planning Department
(PlanD) and Lands Department (LandsD) were consulted on the land use planning
for the nearby areas. LandsD
confirmed that there is no planned development within the nearby three zones,
including the “Village” zone in which Wong Uk Tsuen is located, the
“Undetermined” zone in which Small Trade New Village is located and the
“Agricultural” zone in which scattered village houses are located.
Based on the information provided by the
PlanD, residential developments were planned within the CDA zones, including
Yuen Long Area 12 and Area 15, an Indoor Recreational Centre & Combined
Wholesale Food Market and two educational institutions were planned within the
GIC zone. However, there are no
proposed layouts available for the Indoor Recreational Centre & Combined
Wholesale Food Market and the two educational institutions. As the food market is not noise
sensitive and the indoor recreation centre will likely be installed with
central air-conditioning system and fixed glazing (thereby eliminating its
reliance on openable windows for ventilation), they were not identified as
NSR.
Information
from PlanD indicated that there are a number of schemes approved and remain
valid for the CDA zones, Yuen
Long Area 12 and Area 15.
Assessment points were included in the traffic noise impact assessment
at the boundary of the CDA zones with 180 degrees view angle facing Yuen Long
Highway and the POR. Taken into
account the presence of a drainage reserve, which is a non-building area, along
the eastern and southeastern lot boundaries of Area 15 facing Yuen Long Highway
and Castle Peak Road, assessment points were set back to exclude this
non-building area.
PlanD also confirmed that a Planning
Application for Residential Development with Preservation of Pun
The locations of the identified
representative existing and planned NSRs, and photographs showing the existing
NSRs are presented in Figure 4.3e.
Descriptions of the representative NSRs and the separation distances between
the NSRs and the Project
are provided in Table 4.3a.
Table 4.3a Representative
Noise Sensitive Receivers
|
NSR |
Location |
Use |
No. of Floors |
Ground Level (mPD) |
No. of Dwellings/ Classrooms
Represented |
|
WUT1 |
Wong |
Residential |
3 |
3.9 |
3 |
|
STNV1 |
Small Traders New Village |
Residential |
2 |
3.9 |
2 |
|
JCCAH1 & JCCAH2 |
Jockey Club Care & Attention Home |
Home for the aged |
6 (a) |
4.9 |
70 |
|
V1 |
Village houses facing slip road (south bound)
of Yuen Long Highway - south of POI |
Residential |
2 |
4.6 |
1 |
|
V2 |
Residential |
2 |
4.2 |
1 |
|
|
V3 |
Chuk San Tsuen |
Residential |
2 |
6.6 |
1 |
|
V4 |
Residential |
2 |
7.4 |
1 |
|
|
V5 |
Residential |
4 |
7.8 |
4 |
|
|
V6 |
|
Residential |
3 |
5.3 |
3 |
|
YT1 – YT3 |
|
Residential |
36 |
5 |
720 |
|
KMYLS1 & KMYLS2 |
|
Educational Institution |
5 |
5.3 |
32 |
|
ND1 |
Planned Development at Yuen Long Area 12
(b) |
Residential |
28-44 |
5.1 |
(c) |
|
ND2 & ND3 |
Planned Development at Yuen Long Area 15
(b) |
Residential |
25-39 |
5.1 |
(c) |
|
PS1 |
Planned School(b) |
Educational Institution |
7 |
5.2 |
(c) |
|
PU1 |
Planned Residential Development with
Preservation of Pun |
Residential |
14-17 |
5.0 |
95 |
|
ExSTNVPS1 |
Planned non-school educational use at
the |
Educational Institution |
1 |
3.9 |
6 |
|
Notes: (a)
The
ground floor of this NSR is a lobby with plant rooms, ie not noise-sensitive. (b)
Planned
NSRs for operational noise impact assessment only. (c)
Not
available for planned development. |
|||||
4.4.1
Construction Phase
The construction noise impact assessment was
undertaken in accordance with the procedures outlined in the GW-TM, which is issued under the NCO and the EIAO-TM. The assessment
methodology is summarised as follows:
·
Locate
representative NSRs that may be affected by the Project;
·
Determine
the plant teams for corresponding activities, based on the agreed plant
inventory;
·
Assign
sound power levels (SWLs) to the Powered Mechanical Equipment (PME) proposed
based on the GW-TM, British
Standard BS 5228([1]) and list of SWLs of other commonly used
PME([2]);
·
Calculate
the correction factors based on the distance between the NSRs and the notional
noise source position of the work sites;
·
Apply
corrections in the calculations, such as potential screening effects and
acoustic reflection, if any; and
·
Predict
the construction noise levels at NSRs in the absence of any mitigation
measures.
The construction
noise assessment was undertaken based on the proposed construction works programme and plant inventory
presented in Annexes C2 and C3. The
Project Proponent has reviewed the programme and plant inventory, and has
confirmed that they are reasonable
and practicable for completing the Project within the scheduled
timeframe. The proposed methods for the construction of the Project are common in
Hong Kong and the PMEs proposed are available in the
The total SWL associated with each
construction activity was established. Owing to the small construction
work sites involved in the Project, the construction noise levels at NSRs were
calculated based on the distances between the respective NSRs and their nearest
site boundaries. The potential
noise impacts at NSRs were subsequently evaluated by comparing the predicted
noise levels with the EIAO-TM
day-time construction noise limits (Leq, 30min dB(A)), as outlined
in Section 4.2.1.
4.4.2
Operational
Phase
The road traffic noise impact assessment
due to the improvement to POI was based on the procedures given in Calculation of Road Traffic Noise (CRTN) published by the UK Department of
Transport. The assessment has been
undertaken for the scenarios of with and without the Project during the peak
hour in respect of the maximum traffic projections within a 15 year period
following the commencement of the operation of the Project. The AM peak hour traffic flow for Year
2026 was considered to be the maximum traffic forecast during the period 2011
to 2026, and therefore was adopted for the assessment (Annex B). The traffic forecast employed for this assessment
was endorsed by Transport Department (TD) (Annex B).
The road surface types and speed limits
for the road sections in the Project are indicated in Annex B. The design
information of the proposed roads in Table 4.4a
was agreed by TD:
Table 4.4a Design
Information of the Proposed Roads
|
Proposed Roads |
Road Type |
Road Speed (kph) |
Road Surface |
|
Flyover A |
Rural Trunk
Road |
70kph |
Low Noise Surface |
|
Slip Road A |
Rural Trunk
Road |
50 - 70kph |
Bitumen & Low Noise Surface |
|
Slip Road B |
Expressway |
70 - 80kph |
Low Noise Surface |
|
Slip Road C |
Rural Trunk
Road |
50kph |
Bitumen |
|
Segregated |
Rural Trunk Road |
50kph |
Bitumen |
Based on the as-built drawings provided by
HyD, absorptive noise barriers of 1m to 3.5 m in height were erected along the
road edges of the existing Yuen Long Highway Flyover. Noise barriers of
0.8m to 4m height were also erected along the road edges of the existing slip
roads on the northern arm of Yuen Long Highway. These noise barriers have been included
in the noise model and their locations are presented in Annex C.
Some sections of
the existing noise barriers will have to be demolished for the construction of
the Project, which are presented in Annex C5. The existing 0.8m and 2m noise barriers at
the POR will be demolished after the completion of the new segregated left-turn
lane and its associated planter wall.
A short section of the existing 3m high noise barrier will be required
to setback for about 2m to allow bus sight-line for the new segregated
left-turn lane. This section of
noise barrier will be taken out in the noise model for the Project (without
mitigation) to represent a worse-case scenario.
In accordance with
the policy and requirements set out in the Technical
Circular (Works) No. 10/2005 for Planting
on Footbridges and Flyovers published by the then Environmental, Transport
and Works Bureau, planters will be provided for the new flyover. In addition to the planters, a 1.1m high
concrete parapet wall along the road sides of the new flyover and a 1.5m high
planter wall along the new segregated left-turn lane will be provided following
the requirements of typical highway engineering design to form part of the road
works. These provisions are
incorporated in the noise assessment.
Indicative sections of the proposed concrete parapet wall and the
planter wall are presented in Annex C6.
The predicted noise levels due to the
Project were evaluated by comparison with the EIAO-TM traffic noise limits (L10, 1hr dB(A)), as
outlined in Section 4.2.2.
4.5
Identification of Potential
Impacts
4.5.1
Construction Phase
Noise arising from the construction
activities of the Project will likely have potential noise impacts on the
nearby NSRs if unmitigated. The major activities associated with the
construction phase will involve the use of PME and they are summarised as
follows:
·
Site clearance and site formation;
·
Road
drainage, utilities and water main works;
·
Demolition
of existing structures;
·
Piling
by Continuous Flight Auger (CFA);
·
Construction
of retaining walls and abutments by silent piler;
·
Subway
extension;
·
Construction
of pilecaps and piers;
·
Construction
of new flyover by balanced cantilever precast;
·
Installation
of concrete parapets and planters; and
·
Pavement
construction.
It is anticipated that percussive piling
will not be required. The normal working hours of the Contractor will be
between 07:00 and 19:00 hours from Monday to Saturday (except public
holidays). For construction method Option 1, ie precast segment balanced cantilever
box girder, is adopted for the new flyover deck, construction activities during night-time,
which is within the restricted hours under the NCO, are expected for the
installation of precast concrete segments and the erection of sign gantry to
avoid disruption of traffic on the existing roads during daytime and to ensure
that the launching of precast segments over busy road sections will not
jeopardise road safety. During the
detailed design and the construction of the Project, every effort will be made
to streamline the work cycle for the flyover deck construction to minimise the
requirement for work activities within the restricted hours. If construction method Option 2, ie cast
in-situ deck with conventional temporary works, is adopted, two additional
months will be required for constructing the new flyover and the construction
programme will be revised as shown in Annex C2.
Figure
4.5a indicates the location of work areas.
For construction works planned during the
restricted hours, it will be the responsibility of the Contractor to ensure
compliance with the NCO and the
relevant TMs. In such cases, the Contractor will be required to submit a
CNP application to the Noise Cont
As
indicated in Section 2.3, the Project
may interact with the following concurrent projects:
·
Kau
Hui Development - Engineering Works in Area 16, Yuen Long Phase 2 - Extension
of Road L3 (Project No. 7721CL/B): The proposed project is for the extension of
Road L3 in Yuen Long Area 16 located next to the West Rail Yuen Long
Station. The scope of the project
mainly comprises the extension of an exiting carriageway by about 220m and its
associated drainage and landscape works.
The construction period will commence in August 2008 and end in 2011.
·
Proposed
Left Turn Lane at Pok Oi Interchange for the Development at YOHO Town Phase II:
An exclusive left turn lane in Pok Oi Interchange will be constructed by Sun
Hung Kai Properties Ltd. together with the private development YOHO Town Phase
II. The exclusive left turn lane
will be located in the south-west corner of the interchange, ie, for vehicles
from Shap Pat Heung Interchange to
The locations of concurrent projects
within 300m of the study area are indicated in Figure 2.5a.
The construction programme and plant inventory for the above-mentioned
concurrent projects are not available at this stage. Cumulative noise impacts were assessed
based on an assumed typical plant inventory for small scale road works.
4.5.2
Operational Phase
The objective of the Project is to relieve
the traffic pressure and traffic queues of the existing POR by means of the
flyover, slip roads, segregated left-turn lane and the associated works.
During the operation of the Project, it may increase the road traffic noise
impacts on the nearby NSRs. Practical direct noise mitigation measures
will be recommended, if necessary, to alleviate the potential noise impact.
4.6.1
Construction
Phase
The
predicted construction noise levels during daytime periods for construction method for flyover A Options 1 and 2 are presented in Tables 4.6a and 4.6b, respectively. Details of the noise calculations are
presented in Annex C7.
Table 4.6a Predicted
Construction Noise Levels during Daytime Period (Without Mitigation) (Construction Method for Flayover A - Option 1 : Precast Segment
Balanced Centilever Box Girder)
|
NSR |
Description |
Predicted Maximum Construction Noise
Levels(a), Leq, 30 min dB(A) |
Cumulative Noise Levels, dB(A) |
Noise Criteria, dB(A) |
|
JCCAH1 |
Jockey Club Care & Attention Home –
western facade |
65 – 77 |
65 – 78 |
75 |
|
JCCAH2 |
Jockey Club Care & Attention Home –
southern facade |
54 – 77 |
54 – 77 |
75 |
|
KMYLS1 |
|
62 - 82 |
62 - 82 |
70 |
|
KMYLS2 |
|
51 – 81 |
51 - 81 |
70 |
|
STNV1 |
Small Traders New Village |
65 - 78 |
65 - 79 |
75 |
|
V1 |
Village houses facing slip road (south bound)
of Yuen Long Highway - south of POI |
60 – 74 |
60 – 74 |
75 |
|
V2 |
60 - 76 |
60 - 76 |
75 |
|
|
V3 |
Chuk San Tsuen |
43 – 76 |
43 – 76 |
75 |
|
V6 |
|
54 – 70 |
54 – 70 |
75 |
|
WUT1 |
Wong |
65 – 78 |
66 – 81 |
75 |
|
YT1 |
|
59 - 70 |
59 - 70 |
75 |
|
Notes: (a) All
predicted noise levels were corrected with 3dB(A) for façade reflection. (b) Bold value indicates exceedance of
noise criteria of 75 dB(A) for residential premises, 70 dB(A) for educational
institutions during daytime period. |
||||
Table 4.6b Predicted
Construction Noise Levels during Daytime Period (Without Mitigation) (Construction Method for Flayover A - Option 2 : Cast In-situ Deck with
Conventional Temporary Works)
|
NSR |
Description |
Predicted Maximum Construction Noise
Levels(a), Leq, 30 min dB(A) |
Cumulative Noise Levels, dB(A) |
Noise Criteria, dB(A) |
|
|
JCCAH1 |
Jockey Club Care & Attention Home –
western facade |
67 – 77 |
67 – 78 |
75 |
|
|
JCCAH2 |
Jockey Club Care & Attention Home –
southern facade |
62 – 77 |
62 – 77 |
75 |
|
|
KMYLS1 |
|
67 - 82 |
67 - 82 |
70 |
|
|
KMYLS2 |
|
56 – 81 |
56 - 81 |
70 |
|
|
STNV1 |
Small Traders New Village |
65 - 78 |
66 - 79 |
75 |
|
|
V1 |
Village houses facing slip road (south
bound) of Yuen Long Highway - south of POI |
64 – 74 |
64 – 74 |
75 |
|
|
V2 |
64 - 76 |
64 - 76 |
75 |
||
|
V3 |
Chuk San Tsuen |
53 – 76 |
53 – 76 |
75 |
|
|
V6 |
|
57 – 70 |
57 – 70 |
75 |
|
|
WUT1 |
Wong |
65 – 78 |
68 – 81 |
75 |
|
|
YT1 |
|
62 - 71 |
62 - 71 |
75 |
|
|
Notes: (a) All
predicted noise levels were corrected with 3dB(A) for façade reflection. (b) Bold value indicates exceedance of
noise criteria of 75 dB(A) for residential premises, 70 dB(A) for educational
institutions during daytime period. |
|||||
The results indicate that the construction
noise impacts at most of the NSRs exceeded the EIAO-TM noise criteria during daytime period. Mitigation
measures will therefore be required to mitigate the construction noise impact.
4.6.2
Operational
Phase
Designated Project
Analysis
Road
traffic noise levels have been predicted at a total of 21 representative NSR
locations, including existing and planned uses. Annex C8 presents the breakdown of
the noise levels with and without the Project. The results indicate that the traffic
noise level with the road project is not greater than that without the road
project at the design year by 1.0dB(A) or more at any of the NSRs and will not
result in any adverse impact on the NSRs.
The Project as a whole will not constitute any material change on the
noise front to exempted projects.
Hence, it is not required to consider noise mitigation measures in the
context of the whole project boundary to reduce the traffic noise impacts at
all NSRs to meet the EIAO-TM noise
criteria.
Road Traffic Noise
Without noise mitigation measures in
place, the predicted noise levels at the representative NSRs were in the range
of 58 to 83 dB(A) with the Project.
Results indicated that the predicted noise levels exceeded the traffic
noise criteria due to the Project and other existing roads at the planned NSR
PS1, while exceedance predicted at other NSRs would be due to other existing
roads only. Noise mitigation
measures for the two planned schools are required to alleviate the adverse
traffic noise impact.
Detailed results of the
road traffic noise impact assessment with the road plots and input files are
presented in Annex C9.
4.7
Mitigation of Adverse Environmental Impacts
4.7.1
Construction
Phase
In view of the predicted noise exceedances
during the construction of the Project, the following mitigation measures have
been considered:
·
Good
Site Practice;
·
Use
of quiet PME;
·
Use
of acoustic enclosure;
·
Adoption
of movable noise barriers; and
·
Scheduling
of PME/Construction Activities.
Good Site Practices
Good site practices and noise management
can considerably reduce the impact of construction site activities on nearby
NSRs. The noise benefits of these practices can vary according to
specific site conditions and operations. Since the effect of the good
site practices could not be quantified, the mitigated noise levels calculated
in the subsequent sections have not taken account of this effect. The following
site practices should be followed during the construction of the Project:
·
Only
well-maintained plant should be operated on-site and plant should be serviced
regularly during the construction program;
·
Silencers
or mufflers on construction equipment should be utilized and should be properly
maintained during the construction program;
·
Mobile
plant, if any, should be sited as far away from NSRs as possible;
·
Machines
and plant (such as trucks) that may be in intermittent use should be shut down
between work periods or should be throttled down to a minimum;
·
Plant
known to emit noise strongly in one direction should, wherever possible, be
orientated so that the noise is directed away from the nearby NSRs;
·
Material
stockpiles and other structures should be effectively utilised, wherever
practicable, in screening noise from on-site construction activities; and
·
The
contractor should liaise with the school regarding the examination
periods. Noisy construction
activities, including piling, excavation and earth-breaking works, will be
carried out outside the examination periods.
Use of Quiet PME
The use of quiet PME was considered to be
a practicable means to mitigate the construction noise impact. Quiet
plant is defined as a PME having actual SWL lower than the value specified in
the GW-TM. Quiet PME that have been adopted in the assessment are
summarised in Table 4.7a.
Table 4.7a Sound
Power Level of Quiet PME
|
PME Item |
BS 5228 / EPD QPME
Reference |
Sound Power Level, dB(A) |
|
Excavator |
BS C3/97 |
105 |
|
Mobile crane |
BS C7/114 |
101 |
|
Concrete truck |
BS C6/23 |
100 |
|
Road roller |
BS C8/30 |
101 |
|
Vibratory poker |
BS C6/40 |
98 |
|
Asphalt paver |
BS C8/24 |
101 |
|
Vibratory roller |
BS C3/115 |
102 |
|
Concrete pump |
BS C6/36 |
106 |
|
Excavator |
EPD 00057 |
103 |
Use of Acoustic Enclosure
Temporary acoustic enclosure is a common and effective means
to mitigate the noise impact arising from operation of certain small size PMEs.
A frame covered with noise insulation materials (sound insulation materials
with a superficial surface density of at least 7 kg/m2 or sound
absorbing materials of at least 50mm and average absorption coefficient between
125 Hz and 4000 Hz of 0.4) could at least 5 dB(A) reduction for plant items
such as hand-held breaker and circular wood saw. The locations of the temporary acoustic
enclosure shall be adjusted wherever and whenever necessary to protect the noise
sensitive receivers, the enclosures shall have no openings or gaps.
Adoption of Movable Noise Barriers
The
use of noise barriers will be an effective means to mitigate the noise impact
arising from the construction works, particularly for low-rise NSRs.
Movable noise barriers of 3 m in height with skid footing should be used
and located within a few metres of stationary plant and mobile plant such that
the line of sight to the NSR is blocked by the barriers. The length of
the barrier should be at least five times greater than its height. It is anticipated that the major noise
source of all PMEs, including movable and large PMEs, will be located at a
level lower than the top of the proposed movable barriers, and therefore these
barriers could produce at least a 5 dB(A) noise reduction for mobile plant such
as excavator and roller as well as large scale plant such as a crane.
With reference to A Practical Guide for the Reduction of Noise from
Construction Works, the noise barrier material should have a superficial
surface density of at least 7 kg/m2 and have no openings or gaps. Figure 4.7a shows the approximate locations of the
proposed movable noise barriers for the construction of slip road A facing
Scheduling of PME/Construction Activities
In
view of the limited separation distance between NSRs KMYLS1 and KMYLS2 and the
nearest work sites at slip road A as well as flyover A, the predicted noise
level will still exceed the noise criteria. For NSR KMYLS1, exceedance of 2 dB(A)
during normal teaching period and 7 dB(A) during examination period is
anticipated. For NSR KMYLS2, the
predicted noise level complies with the noise criteria of 70 dB(A) during normal
teaching period. It will however
exceed the noise criteria for examination period by 5 dB(A). Practical mitigation measures with the
use of quiet PMEs and movable noise barriers have been exhausted, taking into
account the engineering and programming point of view. To further alleviate the construction
noise impacts, only one group of PME (Group A or B) will be operated during
road drainage, utilities and water mains works at work site of slip road A (Annex
C10). The predicted noise level at NSRs KMYLS1
and KMYLS2 would comply with the criterion of 70 dB(A) during normal teaching
period. It is recommended to cease
all construction activities at the work sites of slip road A and flyover A
during examination period.
Similar
to the situation for NSRs KMYLS1 and KMYLS2, NSRs STNV1 and WUT1 are located
within a small distance from the nearest work site for road resurfacing and
remarking A and B respectively. The
predicted noise level will still exceed the noise criteria of 75 dB(A) by 1
dB(A). Apart from the use of quiet
PME, it is proposed that only one group of PME (either Group A or Group B)
should be operated during the works within the respective work sites of road
resurfacing and remarking A and B.
The predicted noise level at NSR STNV1 and WUT1 would comply the
relevant noise criteria. The
detailed calculations are presented in Annex
C10.
The
above mitigation measures have been vetted and confirmed by the Project
Proponent as being practicable in completing the works within the scheduled
timeframe. It is considered
practical to specify the total SWL of all plant items to be used on-site so
that flexibility is allowed for the Contractor to select plant items to suit
the construction needs.
With the implementation of the use of
quiet PME, movable noise barriers and scheduling of construction works for various construction activities as
shown in Annex
C10, the mitigated noise levels at the representative
NSRs were calculated and the results for daytime periods for construction method Options 1 and 2 for new flyover deck are summarised in Tables 4.7b and 4.7c,
respectively.
Table 4.7b Predicted
Construction Noise Levels during Daytime Period (With Mitigation) (Construction Method for Flayover A - Option 1 : Precast Segment
Balanced Centilever Box Girder)
|
NSR |
Description |
Predicted Maximum Construction Noise Levels(a),
Leq, 30 min dB(A) |
Cumulative Noise Levels, dB(A) |
Noise Criteria, dB(A) |
|
JCCAH1
|
Jockey
Club Care & Attention Home – western facade |
61
– 72 |
61
– 73 |
75 |
|
JCCAH2 |
Jockey
Club Care & Attention Home – southern facade |
50
– 72 |
50
– 72 |
75 |
|
KMYLS1 |
|
58
– 70 |
58
– 70 |
70 |
|
KMYLS2 |
|
47
– 69 |
47
– 69 |
70 |
|
STNV1 |
Small
Traders New Village |
57
– 75 |
57
– 75 |
75 |
|
V1 |
Village
houses facing slip road (south bound) of Yuen Long Highway – south of POI |
56
– 68 |
56
– 68 |
75 |
|
V2 |
56
– 69 |
56
– 70 |
75 |
|
|
V3 |
Chuk
San Tsuen |
39
– 68 |
39
– 68 |
75 |
|
V6 |
|
50
– 63 |
50
– 63 |
75 |
|
WUT1 |
Wong
|
58
– 74 |
58
– 74 |
75 |
|
YT1 |
|
55
– 64 |
55
– 64 |
75 |
|
Note: (a) All
predicted noise levels were corrected with 3dB(A) for façade reflection. |
||||
Table 4.7c Predicted
Construction Noise Levels during Daytime Period (With Mitigation) (Construction Method for Flayover A - Option 2 : Cast In-situ Deck with
Conventional Temporary Works)
|
NSR |
Description |
Predicted Maximum Construction Noise Levels(a),
Leq, 30 min dB(A) |
Cumulative Noise Levels, dB(A) |
Noise Criteria, dB(A) |
|
JCCAH1
|
Jockey
Club Care & Attention Home – western facade |
62
– 72 |
62
– 73 |
75 |
|
JCCAH2 |
Jockey
Club Care & Attention Home – southern facade |
56
– 72 |
56
– 72 |
75 |
|
KMYLS1 |
|
61
– 70 |
61
– 70 |
70 |
|
KMYLS2 |
|
50
– 69 |
50
– 69 |
70 |
|
STNV1 |
Small
Traders New Village |
59
– 75 |
59
– 75 |
75 |
|
V1 |
Village
houses facing slip road (south bound) of Yuen Long Highway – south of POI |
59
– 68 |
59
– 68 |
75 |
|
V2 |
59
– 69 |
59
– 70 |
75 |
|
|
V3 |
Chuk
San Tsuen |
46
– 68 |
46
– 68 |
75 |
|
V6 |
|
52
– 63 |
52
– 63 |
75 |
|
WUT1 |
Wong
|
60
– 74 |
60
– 74 |
75 |
|
YT1 |
|
57
– 64 |
64
– 64 |
75 |
|
Note: (a) All
predicted noise levels were corrected with 3dB(A) for façade reflection. |
||||
The results indicate that with the
adoption of the recommended mitigation measures, no exceedance of the EIAO-TM noise criteria during the
daytime period is anticipated. No further mitigation will therefore be
required.
For the proposed noise barrier to mitigate
the traffic noise impact on the planned schools due to the Project, it will
only be constructed when there is an implementation programme for the
construction of the planned schools.
The construction noise impact was estimated at the nearest NSRs KMYLS1,
KMYLS2 and YT1. With the use of
quiet PME and movable noise barriers, in conjunction with careful scheduling of
works, the predicted noise levels at the NSRs are anticipated to comply with
the EIAO-TM daytime noise criteria
for residential premises and education institutions during normal teaching
period. Details of the calculations
are given in Annex
C10. It is
recommended to cease all noisy construction
activities at the work site of slip road A and flyover A during examination
periods.
4.7.2
Operational
Phase
With the results of the prediction
indicated noise exceedance at the planned NSR PS1 due to both the Project and
other existing roads, direct mitigation measure would be required to reduce the
noise from the Project to a level that it:
·
is not higher than the EIAO-TM
noise criteria; and
·
has no significant contribution to the
overall noise from other existing roads, if the cumulative noise level (i.e.
noise from the Project together with other existing roads) exceeds the EIAO-TM noise criteria.
The
following direct mitigation measure has been proposed:
·
A
section of approximately 200m long 2.5m high vertical barrier along the northern
bound of Yuen Long Highway in front of the planned schools within the CDA
zone. The barrier is proposed to be
concrete structures installed with reflective barrier panels to align with the
visual appearance of the existing noise-screening structures provided along
Yuen Long Highway. As this section
of barrier was proposed to protect the planned schools, it is only required to
be constructed before the occupation of the planned schools.
The proposed direct mitigation measures are
presented in Annex C11.
With
the provision of the proposed direct mitigation measure, the predicted overall
noise levels at most of the NSRs still exceed the EIAO-TM noise criteria due to the noise contributions from the
other existing roads. However, the
predicted noise levels due to the Project at all NSRs comply with the EIAO-TM noise criteria. Annex
C11 presents the breakdown of the noise levels for the scenarios without
the Project, with the Project (without mitigation) and with the Project (with
mitigation). Detailed results of the
road traffic noise impact assessment with the road plots and input files are
presented in Annex C11.
As
the noise contributions from the Project to the increase in the predicted
overall noise levels at the NSRs are not more than 1.0 dB(A) and the predicted
noise levels due to the Project at all NSRs comply with the EIAO-TM noise criteria, no further
direct mitigation measures are considered effective in mitigating the noise
impact.
4.8
Residual Environmental Impacts
4.8.1
Construction
Phase
With the implementation of the recommended
noise control mitigation measures, the cumulative construction noise levels
from the Project and the concurrent projects would comply with the EIAO-TM daytime noise criteria. No
residual impact is anticipated.
With the
provision of the proposed direct noise mitigation measure, the noise contributions
due to the Project at all representative NSRs would be less than 1.0 dB(A) and
the predicted noise levels due to the Project would all comply
with the EIAO-TM noise criteria. Noise exceedance at the representative
NSRs, if any, would be due to the other existing roads.
As the
contributions from the Project to the increase in the predicted overall noise
levels are not more than 1.0 dB(A), none of the representative NSRs is
considered eligible for indirect technical remedies in the form of acoustic
insulation and air conditioning under the EIAO-TM.
4.9
Environmental Monitoring and Audit
4.9.1
Construction
Phase
With regard to the potential noise impact
arising from the construction activities of the Project on the nearby NSRs, it
is recommended that Environmental Monitoring and Audit (EM&A) be undertaken
during the construction phase of the Project. The EM&A programme is
required to monitor compliance with permissible noise levels. In addition, site audits are recommended
to be undertaken regularly during the construction
phase to ensure that appropriate environmental protection and pollution control
mitigation measures are properly implemented. Details of the EM&A requirements are
provided in Section 10 and the EM&A Manual.
4.9.2
Operational
Phase
Notwithstanding that noise exceedance was
predicted for the planned NSRs only and the existing NSRs will not be subject
to adverse noise impacts during the operational phase of the Project, noise
monitoring is recommended to be carried out during the first year after opening
to ensure noise compliance. Details
of the EM&A requirements are provided in Section 10 and the EM&A
Manual.
4.10.1
Construction
Phase
The construction
noise impacts of the Project during normal daytime working hours were predicted
in this EIA Study. With the use of
quiet PME, movable barriers and scheduling of construction activities, the
noise levels at all representative NSRs are predicted to comply with the
construction noise standards.
4.10.2
Operational
Phase
The potential road
traffic noise impacts were assessed based on the worst case traffic forecast
for Year 2026. The predicted noise
levels exceeded the EIAO-TM noise
criteria due to both Project and other existing roads at the planned schools
within the G/IC site. A direct
mitigation measure was proposed to mitigate the noise impacts at the NSR PS1,
where the predicted noise levels due to the Project exceeded the EIAO-TM noise criteria.
With the proposed
2.5m high vertical barrier for the planned schools, the contributions from the
Project to the increase in the predicted overall noise levels at all
representative NSRs was not more than 1.0 dB(A). The predicted noise levels due to the Project
complied with the EIAO-TM noise
criteria, though the overall noise levels at most of the NSRs would still
exceed the EIAO-TM noise criteria.
However, these noise exceedance are due to the other existing roads.
([1])
British Standard “Noise and Vibration Control on Construction and Open Sites –
Part I”, BS 5228: Part I