4.
NOISE
4.1
This section presents an assessment of
potential noise impacts arising from the proposed project during construction
and operation phase and recommends appropriate mitigation measures, where
necessary.
Environmental Legislation, Standards and Guidelines
4.2
The Noise Control Ordinance (NCO) and
Environmental Impact Assessment Ordinance (EIAO) provide the statutory
framework for noise control. Assessment
procedures and standards are set out in five Technical Memoranda (TMs) listed
below:
·
TM on Environmental Impact Assessment
Process (EIAO-TM);
·
TM on Noise from Construction Work
other than Percussive Piling (GW-TM);
·
TM on Noise from Percussive Piling
(PP-TM);
·
TM on Noise from Construction Work in
Designated Areas (DA-TM);
·
TM on Noise from Places other than
Domestic Premises, Public Places or Construction Sites (IND-TM).
4.3
Noise impacts will be assessed in
accordance with the criteria and methodology given in the Technical Memoranda
(TM) made under the Noise Control Ordinance (NCO) and the Technical Memorandum
on Environmental Impact Assessment Process (EIAO-TM).
4.4
Daytime construction noise, i.e. 0700
– 1900 on weekdays, is under the control of EIAO-TM. According to Table 1B of Annex 5 stipulated in the EIAO-TM: Criteria
for Evaluating Noise Impact, the noise limit is Leq(30 min) 75 dB(A) for
domestic premises and Leq(30 min) 70 dB(A) for schools during normal hours(65
dB(A) during examination) and all other where unaided voice communication is
required. Construction activities other
than percussive piling using powered mechanical equipment (PME) undertaken at
other times (i.e. restricted hours) are under the control of the NCO.
4.5
Between 1900 and 0700 hours and whole
day on Sundays and public holidays, activities involving the use of PME for the
purpose of carrying out construction work are prohibited unless a construction
noise permit (CNP) has been obtained. A
CNP may be granted provided that the Acceptable Noise Level (ANL) for the Noise
Sensitive Receivers (NSRs) can be complied with the requirements in the GW-TM.
ANLs are assigned depending upon the Area Sensitivity Rating (ASR). The
corresponding basic noise levels (BNLs) for evening and night time periods, are
given in Table 4.1.
Table 4.1 Construction Noise Criteria for Activity
other than Percussive Piling
|
Time Period
|
Basic Noise Level (BNLs)
|
|
|
ASR A
|
ASR B
|
ASR C
|
|
Evening (1900 to
2300 hours) 1
|
60
|
65
|
70
|
|
Night (2300 to
0700 hours)
|
45
|
50
|
55
|
Notes: 1 includes Sundays and Public
Holidays during daytime and evening
4.6
The Study Area is generally rural in
nature with low-density population is directly affected by traffic noise from
Tuen Mun Road. Therefore the existing
noise sensitive receivers in the Study Area have been assumed to be ‘ASR
B’. According to Table 4.1, the
construction noise criteria for the sensitive receivers would be 65dB(A) in the
evening and 50dB(A) at night. The NCO
would decide the ASR at the time of assessment of such an application based on
the contemporary situations/conditions.
It should be noted that the situations/conditions around the site may
change from time to time. The ASR
assumed in this EIA report is for indicative assessment only.
4.7
In addition to the general controls on
the use of PME during the restricted hours, the Noise Control Authority has
implemented a more stringent scheme via DA-TM.
Under the DA-TM, the use of five types of Specified Powered Mechanical
Equipment (SPME) and three types of Prescribed Construction Work (PCW) within a
designated area during restricted hours requires a valid CNP. The study area of this project is within the
designated area, therefore, the operation of SPME including hand-held breaker,
bulldozer, concrete lorry mixer, dump truck and hand-held vibratory poker will
be controlled. The PCWs to be
controlled are :
·
Erecting or dismantling of formwork or
scaffolding
·
Loading, unloading or handling of
rubble, wooden boards, steel bars, wood or scaffolding material
·
Hammering
4.8
In general, the CNP would not be
granted for the carrying out of PCW within a designated area during the
restricted hours. The CNP would be
granted for the use of SPME during the restricted hours within a designated
area when the Corrected Noise Level (CNL) for all the SPME proposed to be used
are 15 dB(A) lower than the ANL stipulated in the GW-TM.
Percussive Piling
4.9
Percussive piling works, if necessary,
are required to apply for construction noise permit. PP-TM sets out the
requirements for working and determination of the permitted hours of
operations. ANLs for percussive piling
for different type of NSRs are shown in Table 4.2.
Table 4.2 Acceptable Noise Levels for Percussive
Piling
|
NSR
Window Type or Means of Ventilation
|
ANL, dB(A)
|
|
(i) NSR (or part of NSR) with no windows
or other opening
|
100
|
|
(ii) NSR with central air conditioning
system
|
90
|
|
(iii) NSR with windows or other openings
but without central air conditioning system
|
85
|
Note: 10dB(A)
shall be subtracted from the ANLs shown above for NSRs which are hospitals,
medical clinics, educational institutes, courts of law or other NSRs which are
considered to be particularly noise sensitive by the Authority.
4.10
With effect from 1 October 1999, the
use of diesel, pneumatic and/or steam hammers is prohibited in Hong Kong. The permitted hours of operation for
carrying out the percussive piling work not involving the use of diesel,
pneumatic and steam hammers are listed in Table 4.3.
Table 4.3 Permitted Hours of Operation for Percussive
Piling
|
Amount by which
Corrected Noise Level (CNL) exceeds Acceptable Noise Level (ANL), CNL-ANL
|
Permitted hours of
operation on any day not being a general holiday
|
|
10 dB(A) <
CNL-ANL
|
0800
to 0900 AND 1230 to 1330 AND 1700 to 1800
|
|
0 dB(A) <
CNL-ANL £ 10 dB(A)
|
0800
to 0930 AND 1200 to 1400 AND 1630 to 1800
|
|
CNL- ANL £ 0 dB(A)
|
0700 to 1900
|
4.11
Annex 5 of EIAO-TM : Criteria for
Evaluating Noise Impact defines the criteria L10(1hour) for road
traffic noise at various NSRs:
·
70 dB(A) at the facades of dwellings,
hotels, offices;
·
65 dB(A) at the facades of schools,
places of workshop, courts of law; and
·
55 dB(A) at the facades of hospital.
4.12
If any facades of existing NSRs are
still exposed to predicted noise levels exceeding the relevant noise criteria
after the implementation of all direct mitigation measures, provision of indirect
technical remedies (ITR) in the form of acoustic insulation and air
conditioning should be considered under the EIAO-TM and the ExCo directive
“Equitable Redress for Persons Exposed to Increased Noise Resulting from the
Use of New Roads”. The eligibility for
indirect technical remedies will be tested against the following three
criteria:
·
the predicted overall noise level from
the new road, together with other traffic noise in the vicinity must be above
70 dB(A) for residential dwellings, 65 dB(A) for educational institutions and
55dB(A) for hospitals.
·
The predicted overall noise level is
at least 1.0 dB(A) more than the prevailing traffic noise level.
·
The contribution to the increase in
the predicted overall noise level from the new road must be at least 1.0 dB(A).
4.13
According of the Study Brief, a ‘new’
road is defined when road section undergoes major modification which will
directly result in 25% increase in lanes or substantial changes in alignment or
characters (e.g. change to a high speed road) of existing road. As a result, Siu Lam Interchange and the
section of Castle Peak Road (CPR) from Ka Loon Tsuen to Siu Lam Interchange
were defined as ‘new’ roads. Other
roads such as Tuen Mun Road, Route 10 NLYLH’s Siu Lam Link Roads (SLLR) and
other existing local roads were defined as ‘existing’ roads. Appendix 4.1 illustrates the extent of the
defined new roads and existing roads.
Description of the Environment
4.14
The proposed CPR starts from Ka Loon
Tsuen to the Siu Lam Interchange. In
general, the site is rural with low-density population. A Vocational Training Council Seamen’s
Training Centre, a correctional training school and some scattered village
houses are situated at Tai Lam Kok. A
hospital, a psychiatric centre and the Correctional Services Department Staff
Quarters are located at Siu Lam. The existing noise environment is dominated by
road traffic noise along the existing Castle Peak Road and Tuen Mun Road. The prevailing traffic noise levels at the
existing noise sensitive receivers (NSRs) are in the range of 61 to 81 dB(A)
(Appendix 4.2). With the proposed CPR,
the noise levels at the existing NSRs would likely be higher, if
unmitigated.
Noise Sensitive Receivers
4.15
The Study Area is generally rural in
nature and comprises mainly scattered village houses, low-rise residential
buildings, hospital and educational institutions located mainly at Tai Lam Kok
and Siu Lam.
4.16
According to the So Kwun Wat OZP (No.
S/TM-SKW/4), a comprehensive development area (CDA) is zoned at Tai Lam Chung
(area between Wu Uk and Wong Uk). In
order to assess the traffic noise impact associated with the operation of the
proposed CPR, an assessment point has assigned for the CDA.
4.17
In accordance with the Study Brief, a
number of representative NSRs within the Study Area have been identified for
the construction and traffic noise impact assessments as listed in Table 4.4
and Table 4.5. Locations of the
representative NSRs are illustrated in Figures 4.1 and 4.2.
Table 4.4 Summary
of Representative Noise Sensitive Receivers for Construction Noise Impact
Assessment
|
NSR
|
Location
|
Use
|
Ground elevation (mPD)
|
|
N2A
|
Siu
Lam Hospital Library
|
Library
|
60
|
|
N2F
|
Siu
Lam Hospital
|
Hospital
|
78
|
|
N3H
|
Correctional
Services Department Married Staff Quarter
|
Residential
|
34.8
|
|
N4H
|
Correctional
Services Department Married Staff Quarter
|
Residential
|
27
|
|
N1B
|
Siu
Lam Psychiatric Centre
|
Hospital
|
45.2
|
|
NSC1
|
Customs
& Excise Training School
|
Educational
Institution
|
3.7
|
|
VH1
|
Village
house at Wu Uk Tsuen
|
Residential
|
3
|
|
VTC1
|
Seamen’s
Training Centre
|
Educational
Institution
|
5
|
|
VTC3
|
Seamen’s
Training Centre
|
Educational
Institution
|
5
|
|
KLT
|
Ka
Loon Tsuen
|
Residential
|
18
|
|
AP1
|
Correctional
Services Department Staff Quarter
|
Residential
|
22
|
Table 4.5 Summary
of Representative Noise Sensitive Receivers for Traffic Noise Impact Assessment
|
NSR
|
Location
|
Use
|
Ground
elevation (mPD)
|
Assessment Floors
|
|
N2A
|
Siu
Lam Hospital
|
Library
|
60
|
G/F
|
|
N2F
|
Siu
Lam Hospital
|
Hospital
|
78
|
G/F, 1/F, 2/F
|
|
N3H
|
Correctional Services Department Married
Staff Quarters
|
Residential
|
34.8
|
G/F, 2/F, 4/F
|
|
N4H
|
Correctional Services Department Married
Staff Quarters
|
Residential
|
27
|
1/F, 2/F, 4/F
|
|
N1B
|
Siu
Lam Psychiatric Centre
|
Hospital
|
45.2
|
1/F, 3/F, 4/F
|
|
NSC1
|
Customs and Excise Training School
|
Educational Institution
|
3.7
|
1/F, 3/F, 6/F
|
|
VH1
|
Village
house at Wu Uk Tsuen
|
Residential
|
3
|
1/F, 3/F
|
|
VTC1
|
Seamen’s Training Centre
|
Educational Institution
|
5
|
G/F, 1/F, 2/F
|
|
VTC2
|
Seamen’s Training Centre
|
Educational Institution
|
5
|
G/F, 1/F, 2/F
|
|
VTC3
|
Seamen’s Training Centre
|
Educational Institution
|
5
|
G/F, 1/F, 2/F
|
|
KLT
|
Village house at Ka Loon Tsuen
|
Residential
|
18
|
1/F, 3/F
|
|
PC1
|
Poseidon Coast
|
Residential
|
10
|
1/F, 14/F, 27/F
|
|
AP1
|
Correctional Services Department Staff
Quarter
|
Residential
|
22
|
G/F, 1/F, 2/F
|
|
CDA
|
Comprehensive Development Area at Tai Lam
Chung
|
Residential
|
7.7
|
G/F, 20/F, 40/F
|
Assessment Methodology
Construction Phase
4.18
In accordance with the EIAO, the
methodology outlined in the GW-TM is used for the assessment of construction
noise (excluding percussive piling).
Sound Power Levels (SWLs) of the equipment will be taken from Table 3 of
the GW-TM. Where no sound power level (SWL) was given in the GW-TM,
reference was made to BS 5228:Part 1:1997 Noise
Control on Construction and Open Sites and previous similar studies or from
measurements taken at other sites in Hong Kong. Groups of powered mechanical equipment (PME) have been assigned
for various construction activities of the CPR improvement works. Details of the PME and the total SWLs for
various construction activities are provided in Appendices 4.3a and 4.3b.
4.19
Noise impacts at the nearest sensitive
facades of the residential buildings to the source positions will be
assessed. All PME items required for a
particular construction activity are located at the notional or probable source
position of the segment where such activity is performed. A +3 dB(A) façade correction will be added
to the predicted noise levels in order to account for the facade effect at each
NSR. A sample calculation for the
construction assessment is provided in Appendix 4.4.
4.20
In accordance with the preliminary
construction progamme (Appendix 2.19), the project will last from June 2003 to
June 2007, which includes eight major tasks as listed below:
1. Viaduct from Tai Lam Kok to Siu Lam.
2. Reclamation at Tai Lam Kok.
3. Road widening from Temporary Site Boundary to Tai Lam Kok.
4. Road widening from Ka Loon Tsuen to Temporary Site Boundary.
5. Siu Lam Interchange.
6. Road reconstruction from Temporary Site Boundary to Tai Lam Kok.
7. Road reconstruction from Ka Loon Tsuen to Temporary Site Boundary.
8. Road reconstruction from Tai Lam Kok to Siu Lam.
4.21
As informed by HyD, Bridge No. 15 will
not be reconstructed in this project and therefore construction noise impact
assessment for that is not required.
4.22
Generally, the construction activities
of the project will be carried out in non-restricted hours (0700-1900 hours)
with the exception of dredging works which will be carried out on 24-hour day.
For any 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 CNP application to the Noise Control
Authority and abide by any conditions stated in the CNP, should one be
issued. Therefore, the potential noise
impacts of dredging works proposed within restricted hours are not formally
assessed in this EIA. In order to
facilitate the efforts of the project proponent to avoid any potentially
adverse noise impacts, an indicative assessment (Sections 4.69 – 4.73) is
undertaken at representative NSRs.
4.23
Based on the construction programme
and the assigned PME groups, both the individual and cumulative construction
noise levels from individual and all concurrent construction activities which
are considered to be significant at the NSRs have been assessed.
Operational Phase
4.24
Traffic noise impact was predicted
using the methodology provided in the UK Department of Transport Calculation of
Road Traffic Noise (CRTN) 1988.
According to EIAO-TM, the road traffic noise should be predicted based
on the maximum traffic forecast within 15 years upon the operation of the
proposed roadwork. Year 2022 is considered to be the maximum traffic forecast
and has been adopted for the assessment.
Transport Department has approved the adopted traffic figures. Projected peak hourly traffic flow and
vehicle composition for 2022 is presented in Appendix 2.21.
4.25
Since the completion of Route 10
NLYLH’s SLLR would be deferred until after 2010, a traffic forecast has been
conducted to verify whether the traffic volumes for the case of without Route
10 NLYLH’s SLLR in year 2011 on the proposed CPR would be higher than the
projected figures for 2022. The traffic
forecast results indicate that the projected 2011 traffic flows on the proposed
CPR would be lower than the projected 2022 figures. Hence, the projected 2022 traffic flows would still be valid for
the assessment. Details of the traffic
forecast are given in Appendix 4.8.
4.26
Where appropriate, the prevailing
existing noise levels for the construction year (Year 2003) will also be
predicted in order to determine whether or not NSRs exposed to residual traffic
noise impacts will qualify the Noise Insulation Works under this project.
4.27
The operation speed for the proposed
Castle Peak Road between Ka Loon Tsuen and Siu Lam is 70km/h, which is approved
by Transport Department. The traffic speeds for Tuen Mun Road and the existing
Castle Peak Road adopted in the model are 80km/h and 70km/h respectively. The
operation speed for other existing slip roads and the proposed roundabouts were
assumed to be 50km/h.
4.28
Low noise road surfacing is assumed to
be a standard feature for Tuen Mun Road in the assessment. In accordance with the EIA Final Assessment
Report of the Route 10 NLYLH, it is assumed that the main alignment (excluding
the main span of Tsing Lung Bridge and the toll plaza) and associated slip
roads with speed limit higher than 50km/hr will be surfaced using low noise
road surfacing.
4.29
The following noise mitigation
measures (as shown in Figure 4.3) proposed in the approved EIA Final Report
(Southern Section) of Route 10 have been included in the assessment.
·
A 400 m long, 5m tall absorptive
vertical barrier on the eastern edge of southbound Route 10 NLYLH’s SLLR;
·
A 150 m long, 5m tall absorptive
vertical barrier on the eastern edge of northbound Route 10 NLYLH’s SLLR;
·
A 230 m long, full enclosure for
southbound Route 10 NLYLH’s SLLR;
·
A 370 m long , semi-enclosure on the
eastern edge of Route 10 NLYLH’s SLLR;
·
A 360 m long, semi-enclosure on the
eastern edge of northbound Route 10 NLYLH’s SLLR;
·
A 230 m long, full enclosure for
northbound Route 10 NLYLH’s SLLR;
·
A 140 m long, 5m tall absorptive
vertical barrier on western edge of northbound Route 10 NLYLH’s SLLR.
4.30
The alignment of the Route 10 NLYLH’s
SLLR adopted in the assessment has made reference to the Drawings Nos.
524/BRG/509 to 511 as provided by HyD.
Based on the available information, no noise barriers on the section of
Tuen Mun Road at Siu Lam are included in the assessment.
4.31
The road network, proposed building
layout and all other features that could have noise screening or reflective
effects, were taken into account in the road traffic noise model. The roads were divided into segments. A road layout defines the road width, road
surface type and traffic mix, flow and road design speed. The segmentation and calculation process
were carried out using a model based on the CRTN, which is agreed by EPD. Noise
levels were calculated at each receiver point at three different elevations
(i.e. 1st floor, mid floor and top floor). A sample calculation is provided in Appendix 4.5 for reference.
Identification of Impacts
Construction Phase
4.32
The major noisy construction tasks
would be the construction of viaduct from Tai Lam Kok to Siu Lam and road
reconstruction from Tai Lam Kok to Siu Lam. It is anticipated that Seamen’s
Training Centre, Customs and Excise Training School, Correctional Services
Department Married Staff Quarters and Siu Lam Psychiatric Centre may be
affected by the construction noise arising from the project.
4.33
As indicated in Table 2.1, the project
‘Castle Peak Road Improvement from Sham Tseng to Ka Loon Tsuen (Project 553TH)’
would likely be carried out concurrently with the proposed project. However, all the identified representative
NSRs are located at a distance of more than 300m from the site boundary of the
Project 553TH with the exception of NSR KLT.
As illustrated on Figure 4.1, apart from the work site of Ka Loon Tuen
to Temporary Site Boundary, all other work sites are located more than 300m
from the NSR KLT. In addition, the
construction programme indicates that the section of proposed CPR from Ka Loon
Tuen to Temporary Site Boundary will be constructed upon the completion of the
Project 553TH. Hence, cumulative
construction noise impact from the Project 553TH is not anticipated.
4.34
As indicated in Section 2.67, it is
anticipated that the construction of Route 10 NLYLH’s SLLR will not be
undertaken concurrently with the project.
Hence no cumulative construction noise impact from the Route 10 Project
is expected.
Operational Impacts
4.35
This project is a road improvement
work. The proposed works are carried
out along the coastal area from Ka Loon Tsuen to Siu Lam. The widening section between Ka Loon Tsuen
and Tai Lam Kok is not expected to adversely affect any residential or other
kinds of development due to the topographical conditions. On the other hand, the additional dual-two
lanes from the section between Tai Lam Kok and Siu Lam Interchange would likely
enhance the traffic noise impacts on the nearby NSRs such as Seamen’s Training
Centre and Correctional Services Department Married Staff Quarters. Appropriate
noise mitigation measures may be required to alleviate any traffic noise
impact.
Prediction and Evaluation of Impacts
Construction Phase
4.36
As broadly illustrated in the
construction programme (Appendix 2.19), various construction activities may be
carried out concurrently during a particular period. Cumulative noise impacts arising from different construction
activities of the proposed project on the representative NSRs have been
predicted and the results are presented in Appendix 4.6a.
4.37
As indicated in Appendix 4.6a, the
cumulative noise levels at the representative NSRs are predicted to range from
45 dB(A) to 84 dB(A). Apart from NSRs
N4H, the cumulative noise levels at all NSRs are predicted to exceed the noise
criteria of 75 dB(A) for residential uses and 70 dB(A) for schools during
normal hour and the place where unaided voice communication is required. Mitigation measures are therefore required
to alleviate the construction noise impacts.
Operational Phase
4.38
Unmitigated traffic noise levels at
the 14 representative NSRs have been predicted and the results are given in
Appendix 4.7a. Table 4.6 summarizes the
potential traffic noise impacts associated with the project.
4.39
As indicated in Appendix 4.7a, the
unmitigated road traffic noise levels at the representative NSRs are predicted
to range from 62dB(A) to 82dB(A). Apart
from CDA and the lower floor of VH1 and PC1, the noise levels at all the NSRs
would exceed the noise criteria of 70dB(A) for residential uses, 65dB(A) for
educational institutions and 55dB(A) for hospitals. A breakdown of the overall noise levels indicates that most of
the exceedances are primarily attributable to existing roads. With the exception of N2F, N3H, N4H, N1B,
VTC2 and VTC3, the noise levels from new roads at all the NSRs would be below
the noise criteria and contribute less than 1dB(A) to the overall noise levels. In order to abate the traffic noise impact
arising from the proposed CPR on the affected NSRs, noise mitigation measures
are required.
Table 4.6 Potential
Traffic Noise Impacts
|
NSR
|
Residential Premises/Schools
|
Exceedance of the Noise Criteria1, dB(A)
|
Estimated
Number of dwellings /classrooms/noise sensitive elements
|
|
|
Exceed the
Noise Criteria
|
Exceed the
Noise Criteria with New Roads Contribution >1dB(A)
|
|
N2A
|
Siu Lam Hospital (Library)
|
6
|
Whole block
|
0
|
|
N2F
|
Siu Lam Hospital
|
13 – 17
|
Southern block
|
Ground floor of
Southern block
|
|
N3H & N4H
|
Correctional
Services Department Married Staff Quarters
|
5 – 10
|
30
|
20
|
|
N1B
|
Siu lam
Psychiatric Centre
|
17
|
Whole block
|
0
|
|
NSC1
|
Customs and Excise
Training School
|
9
|
15*
|
0
|
|
VH1
|
Village house at
Wu Uk Tsuen
|
1
|
5
|
0
|
|
VTC1, VTC2 &
VTC3
|
Seamen’s Training
Centre
|
14 – 17
|
10*
|
0
|
|
KLT
|
Village House at
Ka Loon Tsuen
|
2
|
5
|
0
|
|
PC1
|
Poseidon Coast
|
6
|
120
|
0
|
|
AP1
|
Correctional
Services Department Staff Quarter
|
12
|
10
|
0
|
|
CDA
|
Comprehensive
Development Areas at Tai Lam Chung
|
0
|
0
|
0
|
|
Total (exclude the hospitals)
|
170/25*
|
20
|
Note:
1 70dB(A) for residential
dwellings, 55dB(A) for hospitals and 65dB(A) for schools
* denotes classroom
Mitigation of Adverse Environmental Impacts
Construction Phase
Good Site Practice
4.40
Although the noise mitigation effects
are not easily quantifiable and the benefits are specific to the site and
operating conditions, good site practices are easy to implement and do not
impact upon the works schedule. The
following site practices should be followed during each phase of construction:
·
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 utilised 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.
Adoption of Quieter Plant
4.41
In order to reduce the excessive noise
impacts at the affected NSRs, quieter plants are recommended. The type of quiet PMEs adopted in this
assessment is not a must that the Contractors have to use specific items of
plant for the construction operations.
The Contractors are allowed to use other type of quiet PMEs, which have
the same total SWL, to meet their need.
4.42
The silenced PMEs adopted in the
assessment were taken from the BS5228: Part 1:1997, which are known to be in
Hong Kong (Appendix 4.3c). It should be
noted that the silenced PME can be found in Hong Kong. However, the EPD, when processing a CNP
application, will apply the SWL of a particular plant specified in the GW-TM
unless the noise emission of a particular piece of equipment can be validated
by a certificate or demonstration. With
the implementation of the silenced PMEs, the noise levels at the representative
NSRs have been predicted and are given in Appendix 4.6b.
4.43
With the use of the quiet PMEs, a
noise reduction of 2-8 dB(A) could be achieved, depending on the type of
construction activities. The results
show that cumulative construction noise levels arising from various construction
activities of the project at all the NSRs would comply with the EIAO-TM noise
criteria, except NSRs VTC1, VTC3, NSC1, and N3H. Therefore, further noise mitigation measures are required for
these NSRs.
Adoption of Quiet PMEs and Movable Noise Barriers
4.44
With the use of quiet PMEs, exceedances
of the EIAO-TM noise criteria are still predicted at the representative NSRs
VTC1, VTC3, NSC1, and N3H. Therefore
movable noise barriers are recommended in order to screen the noise from a
particular plant. It is anticipated
that a movable noise barrier with a skid footing and a cantilevered upper
portion located close to the noise generating part of the PME such that the
line of sight could be blocked by the barriers when viewed from NSRs, can
produce at least 10 dB(A) screening for stationary plant and large plant such
as vibratory poker, compactor and air compressor and 5 dB(A) for mobile plant
including mobile crane, excavator, concrete pump truck, winch and roller. The use of this measure has only been
applied to the following construction activities:
·
Viaduct from Tai Lam Kok to Siu Lam :
Piling, pile cap construction, bridge piers & abutment construction,
casting of bridge beams and lifting of bridge beams
·
Siu Lam Interchange : relocation of
CLP power sub-station, bored pile wall construction, road embankment,
realignment of access road, roundabout modification, road pavement, utilities,
footpath and road furniture
4.45
With the adoption of the quiet PMEs
and movable noise barriers, a noise reduction of 1-4dB(A) would be achieved
(Appendix 4.3d). The result (Appendix
4.6c) shows that all the NSRs would comply with the noise criteria of 75dB(A)
for residential uses and 70dB(A) for schools during normal school hours. However, the use of the recommended direct
mitigation measures is still insufficient to reduce the construction noise
levels at the educational NSRs VTC1, VTC3 and NSC1 to below the noise criterion
for schools during examination period.
Noise exceedances of the noise criterion for schools during examination
period by 1 to 4dB(A) are still predicted at NSRs VTC3 (August 2003 - April
2004, June - August 2004, November 2004, September 2005 and January 2006–
February 2007), VTC1 (August 2003 - April 2004 and November 2004) and NSC1
(April-December 2006 and February 2007).
4.46
In order to reduce the potential noise
impacts on the schools during examination, further mitigation measures
including restriction on the usage of operating PME and re-scheduling the
construction activities are proposed.
Restriction on PME usage has been tested by limiting the number of plant
used for the construction activities which may generate excessive noise levels
to the educational NSRs. The following
construction activities have been chosen to reduce the number of plant in
operation:
·
Road reconstruction from Tai Lam Kok
to Siu Lam: road construction (excavation of existing pavement, road pavement,
footpath and road furniture), utilities, fill slopes recompaction, cut slopes
stabilization (soil nailing to cut slopes).
·
Reclamation at Tai Lam Kok: dredging
and sand filling.
4.47
With the adoption of the quiet PMEs,
movable barriers and restriction on the usage of operating PME (Appendix 4.3e),
only around 1-2dB(A) exceedances of the noise criterion for schools during
examination are predicted at the educational NSRs and the duration of the
exceedances could be shortened (Appendix 4.6d). The exceedances at VTC3 would last from August 2003 to April
2004, July to December 2006 and February 2007, at VTC1 from August 2003 to April
2004, and at NSC1 from July-September 2006.
Based on the construction programme, the noise exceedances are mainly
due to the cumulative effect of some noisy construction activities in the
vicinity of the NSRs. Table 4.7
presents the duration of the exceedances and the major concurrent construction
activities which lead to the exceedances.
Table 4.7 Duration of
Exceedance of Noise Criterion for School during Examination Period
|
NSRs
|
Major
Concurrent Construction Activities Lead to the Exceedance of Noise Criterion
for Schools during Examination Period.
|
Duration
of Exceedance of Noise Criterion for Schools during Examination Period.
|
|
VTC1
|
Piling
works for viaduct from Tai Lam Kok to Siu Lam and dredging works at Tai Lam
Kok
Piling
works for viaduct from Tai Lam Kok to Siu Lam and seawall construction at Tai
Lam Kok
Pile
cap, bridge pier & abutment and filling works at Tai Lam Kok
|
August
and September 2003
October
2003-February 2004
March-April
2004
|
|
VTC3
|
Piling
works for viaduct from Tai Lam Kok to Siu Lam and dredging works at Tai Lam
Kok
Piling
works for viaduct from Tai Lam Kok to Siu Lam and seawall construction at Tai
Lam Kok
Pile
cap, bridge pier & abutment and filling works at Tai Lam Kok
Fill
slope recompaction and soil nailing to cut slopes (cut slopes stabilization)
for road reconstruction from Tai Lam Kok to Siu Lam
|
August
and September 2003
October
2003-February 2004
March-April
2004
July
-December 2006 and February 2007
|
|
NSC1
|
Fill
slopes recompaction and soil nailing to cut slopes (cut slopes stabilization)
along the existing Castle Peak Road from Tai Lam Kok to Siu Lam
|
July-September
2006
|
4.48
Rescheduling of the concurrent
construction activities as shown in the above table to avoid simultaneous
operating during the examination period is required so as to reduce the
potential noise impact to comply with the noise criterion of 65dB(A).
Operational Phase
4.49
In order to reduce the traffic noise
impacts on the affected NSRs, a mitigation package (Mitigation 1) has been
developed and evaluated for effectiveness.
The recommended noise mitigation measures are described below:
·
A 5 m high vertical barrier of about
430 m located at westbound carriageway of the Castle Peak Road viaduct (CH 170
– CH 600);
·
A 3.5m high vertical barrier of about
92 m located at northbound carriageway of the slip road to the Siu Lam
Interchange;
·
A cantilevered barrier (5.5m high
vertical barrier with a 3m cantilever at 45 degrees to the horizontal) of
around 25m located behind the footpath of Castle Peak Road; and
·
A cantilevered barriers (5.5m high
vertical barrier with a 3m cantilever at 45 degrees to the horizontal) located
of around 795m at eastbound carriageway of the Castle Peak Road viaduct (CH186
– CH978)
4.50
Locations of the above recommended
noise barriers are shown in Figure 4.3
4.51
With the adoption of the recommended
mitigation measures, the noise levels at the representative NSRs have been
predicted and are presented in Appendix 4.7a.
Mitigated traffic noise levels at the NSRs are in the range of 62 to 82
dB(A). The results show that the noise
levels from new roads at N1B, N4H, VTC2 and VTC3 could be reduced to be within
the noise criteria and contribute less than 1dB(A) to the overall noise
levels. While the new road noise levels
at N2F and N3H would still exceed the noise criteria of 55dB(A) for hospitals
and 70dB(A) for residential by 1-3dB(A).
Hence, further mitigation measures are considered in order to reduce the
new road noise levels at these NSRs to meet the noise criteria.
4.52
According to the Noise Insulation
Works for Improvement to Castle Peak Road from Siu Lam to So Kwun Tan, noise
insulation works (NIW) have been installed for all the affected units of the
CSD Married Staff Quarters (H3H and H4H) in the form of air conditioning and
acoustic insulation. Nevertheless, direct
mitigation measures on roads would also be considered in this study.
Further Mitigation Measures
4.53
With the adoption of the recommended
mitigation measures (mitigation 1), the new road noise levels at N3H and N2F
would still exceed the noise criteria.
In view of the modeling result, it is shown that the new road noise
exceedances at N2F and N3H are mainly attributable to traffic noise from the
proposed Siu Lam Interchange. In order
to reduce the new road noise levels at these NSRs, a range of noise mitigation
measures such as more extensive noise barriers/enclosures, low noise road
surfacing and realignment of the roundabout at Siu Lam have been
considered.
Realignment of Roundabout
4.54
It is considered that relocation of
the roundabout at Siu Lam Interchange further away from N3H is not feasible due
to the following constraints in sitting the proposed roundabout:
·
Interface with PWP item no. 6541 TH
(Section 2.32);
·
Castle Peak Road flyover over Tuen Mun
Road (Section 2.33);
·
Access road leading to CSD staff
quarters (Section 2.34);
·
CLP power sub-station (Section 2.35);
and
·
CSD septic tank (Section 2.36).
4.55
The one selected which is a
compromised layout taking into account of the aforementioned constraints, which
were approved by HyD, TD and CSD.
4.56
Alternative layout of the roundabout
(Option 1B) as described in Section 2.51 is also considered because this layout
would allow room for erecting noise barrier at the western periphery of the
roundabout to screen out traffic noise from the roundabout. The similar set of noise mitigation measures
recommended in Mitigation 1 has been tested for this alternative layout. Owing to the absence of the CSD access road
exit at the roundabout, a cantilevered barrier is allowed to be erected at the
western periphery of the roundabout (Figure 4.4). The result (Appendix 4.7b) indicates that the new noise levels at
N3H and N2F would still exceed the noise criteria by 1-2dB(A) and 1-3 dB(A),
respectively. Considering that there
would be safety concern at the junction where the access road join the slip
road to Tuen Mun Road, the alternative layout is not considered.
Low Noise Road Surfacing
4.57
A Guidance Notes on Noise Reducing
Road Surfacing (2nd Draft) have been developed by a Steering Group
chaired by the Deputy Director of HyD and comprised representatives from
Research and Development Division of HyD, PELB, TB and EPD. According to the Guidance Notes, noise
reducing road surface should be applied for low speed roads (<50km/hr)
subject to the following conditions:
·
Not on inclined roads;
·
No sharp bend in road geometry
·
Average annual daily traffic not
exceeding 18,500 in traffic volume and percentage of commercial vehicles not
exceeding 35%; and
·
Not on roads where a minimum crossfall
of 2.5% cannot be practically achieved to drain water to roadside gullies
effectively.
4.58
In addition, as low noise road
surfacing has high air void content and is susceptible to damage when subjected
to acceleration, braking and turning movements (when approaching or leaving
roundabouts) particularly on inclined local roads.
4.59
For the proposed CPR, the traffic
speed at the roundabout and the slip road would be 50kph, which is classified
as low speed roads. Since the slip road
is inclined at more than 1% and the roundabout will have sharp bend in road
geometry, low noise road surfacing (LNRS) is not appropriate to be applied for
the roundabout and the slip road as well as the section of CPR approaching the
roundabout. Hence, LNRS is not
considered for the roundabout and the slip road at the Siu Lam Interchange.
More Extensive Noise Barriers/Enclosures
4.60
A more extensive noise mitigation
package (Mitigation 2) has been developed so as to abate the traffic noise
impact on the CSD Married Staff Quarters and Siu Lam Hospital. The mitigation measures are recommended as
follows:
·
A cantilevered barriers (5.5m high
vertical barrier with a 5m cantilever at 45 degrees to the horizontal) of
around 25m located behind the footpath of Castle Peak Road;
·
A cantilevered barriers (5.5m high
vertical barrier with a 3m cantilever at 45 degrees to the horizontal) of
around 15m located at northbound carriageway of the slip road to the Siu Lam
Interchange;
·
A full enclosure of around 76 m at the
slip road to the Siu Lam Interchange (CH102-CH178);
·
A full enclosure of around 175 m at
the Castle Peak Road viaduct (CH175-CH350);
·
A cantilevered barriers (5.5m high
vertical barrier with a 3m cantilever at 45 degrees to the horizontal) of
around 604m located at eastbound carriageway of the Castle Peak Road viaduct
(CH350 – CH954);
4.61
Locations of the above recommended
noise barriers are shown in Figure 4.5.
4.62
With the adoption of the Mitigation 2,
mitigated traffic noise levels at the NSRs have been predicted and are given in
Appendix 4.7a. The mitigated noise
levels at the NSRs are predicted to range from 62 to 82 dB(A). The result shows that the adoption of the
proposed mitigation measures could reduce the new road noise levels at all NSRs
to be within the EIAO-TM noise criteria of 55dB(A) for hospitals, 65dB(A) for
schools and 70dB(A) for residential. In
addition, the mitigated new road levels would contribute less than 1dB(A) to
the overall noise levels. Although the
overall noise levels at all NSRs would still exceed the EIAO-TM noise criteria,
the exceedances are mainly attributable to the existing roads. Any further mitigation applied to the new
road would not be effective to protect the NSRs to be within the criteria. Hence, no further mitigation measures are
considered.
Evaluation of Residual Environmental Impacts
Construction Phase
4.63
With the implementation of all
appropriate and practical mitigation measures, the cumulative construction
noise levels at all the residential NSRs would comply with the EIAO-TM noise
criteria of 75dB(A) and hence no residual impact on the residential NSRs is
anticipated.
4.64
For the educational NSRs (VTC1, VTC2
and NSC1), the use of the recommended direct mitigation measures would protect
them against noise exceedance of the noise criterion for schools during normal
hours. However, it is still
insufficient to protect the educational NSRs against noise exceedances of the
criterion for school during examination period. In order to reduce the potential noise impacts on the schools,
restriction on the usage of operating PME and re-scheduling of construction
activities to avoid concurrently operating are required during the examination
period.
4.65
A summary of the maximum cumulative
construction noise levels from various construction activities of the project
at the representative NSRs is shown in Table 4.8.
Table 4.8 Summary
of Maximum Cumulative Construction Noise Levels at
the Representative NSRs
|
NSR
|
Description
|
Criteria
dB(A)
|
Maximum Predicted Construction Noise Levels dB(A)
|
|
Unmitigated
|
Quiet Plant
|
Quiet Plant + Movable noise barrier
|
Quiet Plant + Movable Noise Barrier + Restriction on
Usage of Operating PME
|
|
KLT
|
Ka Loon Tsuen
|
75
|
77
|
71
|
--
|
--
|
|
VTC3a
|
Seamen’s Training Centre
|
70 (65)
|
78b
|
72 b
|
70 b
|
67 b
|
|
VTC1a
|
Seamen’s Training Centre
|
70 (65)
|
75b
|
70 b
|
69 b
|
67 b
|
|
VH1
|
Village house at Wu Uk Tsuen
|
75
|
79
|
73
|
--
|
--
|
|
NSC1a
|
Customs and Excise Training School
|
70 (65)
|
77b
|
70 b
|
69 b
|
66 b
|
|
N1B
|
Siu Lam Psychiatric Centre
|
70
|
78
|
72
|
70
|
--
|
|
N2A
|
Siu Lam Hospital (Library)
|
70
|
76
|
70
|
--
|
--
|
|
N2F
|
Siu Lam Hospital
|
70
|
79
|
73
|
70
|
--
|
|
AP1
|
Correctional Services Department Staff Quarter
|
75
|
79
|
73
|
--
|
--
|
|
N3H
|
Correctional Services Department Married Staff
Quarters
|
75
|
84
|
78
|
75
|
--
|
|
N4H
|
Correctional Services Department Married Staff
Quarters
|
75
|
72
|
--
|
--
|
--
|
Note: a Denotes
school
b indicate an exceedance of the EIAO-TM
noise criteria of 65dB(A) for schools during examination period
Bold figures indicate an exceedance of the EIAO-TM
noise criteria of 75 dB(A) for Residential uses and 70dB(A) for schools during
normal school hours
Operational Phase
4.66
Two packages of direct mitigation
measures (Mitigation 1 and Mitigation 2) has been developed and evaluated. The result verified that Mitigation 2 is
preferable as the recommended mitigation measures could abate the new road
noise levels at all the NSRs to comply with the EIAO-TM noise criteria and the
mitigated new road noise levels would contribute less than 1dB(A) to the
overall noise levels. The effectiveness
of the noise mitigation measures recommended in Package 2, in terms of number of
NSRs which will either be protected or benefited (by at least 1dB(A)), is
summarised in Table 4.9.
Table 4.9 Effectiveness
of Recommended Mitigation Measures
|
NSR
|
Description
|
Estimated
Number of Residential Dwellings/Classrooms
|
|
Exceed the Noise Criteria1
|
Exceed the Noise Criteria with New Roads
Contribution >1dB(A)
|
Protected within Criteria1
|
Benefited (by ³
1dB(A)
|
|
N2A
|
Siu Lam Hospital (Library)
|
Whole block
|
0
|
0
|
0
|
|
N2F
|
Siu Lam Hospital
|
Southern block
|
0
|
0
|
0
|
|
N3H & N4H
|
Correctional
Services Department Married Staff Quarters
|
30
|
0
|
2
|
30
|
|
N1B
|
Siu lam
Psychiatric Centre
|
Whole blocks
|
0
|
0
|
0
|
|
NSC1
|
Customs and Excise
Training School
|
15*
|
0
|
0
|
0
|
|
VH1
|
Village house at
Wu Uk Tsuen
|
5
|
0
|
0
|
0
|
|
VTC1, VTC2 &
VTC3
|
Seamen’s Training
Centre
|
10*
|
0
|
0
|
0
|
|
KLT
|
Village House at
Ka Loon Tsuen
|
5
|
0
|
0
|
0
|
|
PC1
|
Poseidon Coast
|
120
|
0
|
0
|
0
|
|
AP1
|
Correctional
Services Department Staff Quarter
|
10
|
0
|
0
|
0
|
|
CDA
|
Comprehensive Development Area at Tai Lam Chung
|
0
|
0
|
0
|
0
|
|
|
Total
|
170/25*
|
0
|
2
|
30
|
Note:
1 70dB(A) for residential dwellings
and 65dB(A) for schools
* denotes classroom
4.67
As shown in the above table, the use
of the mitigation measures could protect about 2 residential dwellings against
noise criteria exceedances and about 30 residential dwellings could be
benefited by more than 1dB(A) noise reduction.
No NSR exceeds the noise criteria with new roads contribution greater
than 1dB(A). This indicates that the
exceedances are mainly attributable to the existing roads. Any further mitigation applied to the new road
would not be effective to protect the NSRs to be within the criteria.
4.68
The residual impacts have been
assessed against the noise insulation criteria (Section 4.12), and the result
is summarized in Appendix 4.7c. The
results show that all the residential dwellings, educational institutions and
hospitals would not meet the criteria and therefore ITR in the form of window
insulation and air conditioning would not be required.
Construction Activities during Restricted Hours
4.69
As mentioned in Section 4.22, the
dredging works will be carried out during the restricted hours (1900-2300 and
2300-0700) and therefore will be under the control of the GW-TM. An indicative assessment has been undertaken
to investigate the potential noise impact arising from the dredging works which
are expected to be performed in restricted hours in accordance with the
criteria and methodology stated in the GW-TM.
As discussed in Section 4.6, the construction noise criteria of 65dB(A)
in the evening and 50dB(A) at night are adopted in this assessment.
4.70
Apart from KLT and VH1, all the NSRs
are located at a distance of more than 500m from the dredging area. Hence, only KLT and VH1 were selected for
this indicative assessment. The PMEs
and the total SWL for dredging works are provided in Appendix 4.3b. The construction noise levels at these two
NSRs during the restricted hours have been predicted and the results are
presented in Table 4.10.
Table 4.10 Construction Noise
Levels at Representative NSRs During Restricted Hours (Unmitigated)
|
NSR
|
Predicted
Noise Level, dB(A)
|
|
KLT
|
58
|
|
VH1*
|
51
|
Note: * assumed
10dB(A) reduction due to topographical screening
4.71
As indicated in Table 4.10, the noise
levels at both NSRs are predicted to comply with the noise criterion of 65dB(A)
in the evening, whereas exceed the nighttime noise criterion of 50dB(A). In order to reduce the noise impact arising
from the dredging activities during nighttime, it is recommended to reduce the
number of barges from four to two and grab dredgers from two to one during the
dredging activities at night (2300-0700) (Appendix 4.3e). Table 4.11 shows the predicted noise levels
at the NSRs with the implementation of restriction on the usage of operating
PME.
Table 4.11 Construction Noise
Levels at Representative NSRs During Restricted Hours (Mitigated)
|
NSR
|
Predicted
Noise Level, dB(A)
|
|
KLT
|
55
|
|
VH1*
|
48
|
Note: * assumed
10dB(A) reduction due to topographical screening
4.72
As indicated in Table 4.11, the
mitigated noise level at VH1 is predicted to comply with the nighttime noise
criterion of 50dB(A), whereas the mitigated noise level at KLT is still predicted
to exceed the nighttime noise criterion by 5dB(A). Hence, it is recommended that the dredging works is required to
avoid undertaking at night along the coastal area between Ka Loon Tsuen and Tai
Lam Kok. According to the preliminary
construction programme, there will be a total of around 104 days allowable for
the dredging works from Ka Loon Tsuen to Tai Lam Kok. If nighttime dredging (2300-0700) is prohibited, the daily
dredging rate will be reduced from 3000 m3 per day (assumed 24
hours) to 2000 m3 per day.
It is estimated that the volume of material to be dredged from Ka Loon
Tsuen to Tai Lam Kok is 196,245 m3.
With the daily dredging rate of 2000 m3 per day, the time
required for the dredging works from Ka Loon Tsuen to Tai Lam Kok will be around
98 days which is less than the allowed period of 104 days. Hence, it is considered feasible to avoid
dredging works undertaking at night along the coastal area between Ka Loon
Tsuen and Tai Lam Kok based on the preliminary construction programme.
4.73
It should be noted that the result of the construction
noise impact assessment for restricted hours is for indicative purpose
only. The Noise Control Authority will
process any CNP application, based on the NCO and the relevant TMs in addition
to considering the contemporary situations/conditions.
Environmental Monitoring and Audit
Construction Phase
4.74
An Environmental Monitoring and Audit
(EM&A) programme is recommended to be established according to the
predicted occurrence of noisy activities.
All the recommended mitigation measures should be incorporated into the
EM&A programme for implementation during construction. Details of programme are provided in a
stand-alone EM&A Manual.
Operational Phase
4.75
It is recommended that traffic noise
monitoring is carried out at representative NSRs within one year of the road
opening. The recommended mitigation
measures, monitoring procedures and locations are presented in the EM&A
Manual.
Conclusion
Construction Phase
4.76
Noise arising from the construction
activities of the project would have potential impact on the noise sensitive
receivers (NSRs) located in the vicinity of the work sites. Unmitigated cumulative construction noise
levels at the representative NSRs have been predicted, which are in the range
of 45 dB(A) to 84 dB(A). The results
indicate that the cumulative noise levels at most of the NSRs would exceed the
EIAO-TM noise criteria.
4.77
Sufficient noise control measures
would be required to mitigate the noise levels to the EIAO-TM noise
criteria. Mitigation measures
recommended include good site practices, the use of quiet plant, movable noise
barriers and restriction on the usage of operating plant.
4.78
With the adoption of the recommended
control measures, all the residential NSRs could be protected against the
construction noise impact. For the
educational NSRs (VTC1, VTC3 and NSC1), the use of the recommended direct
mitigation measures would protect them from exceedance of the noise criterion
for schools during normal hours, whereas it is still insufficient to protect
them from exceedance of the noise criterion for school during examination
period. In order to reduce the
potential noise impacts on the schools, restriction on the usage of operating
PME and re-scheduling of construction activities to avoid concurrently
operating are required during the examination period.
Operational Phase
4.79
Potential road traffic noise impact
associated with the project has been assessed for the maximum traffic flows in
2022. The modeling results indicate
that about 170 residential dwellings and 25 classrooms are likely to experience
noise levels exceeding the EIAO-TM traffic noise criteria, if unmitigated. Hence direct mitigation measures would be
required.
·
4.80
With the implementation of the
recommended direct mitigation measures, the mitigated noise levels from new
roads at all NSRs are predicted to be below 70dB(A) and the new roads
contribution would be less than 1dB(A) to the overall noise levels. It is estimated that about 30 residential
dwellings could be benefited by more than 1dB(A).
4.81
The residual impacts have been
assessed against the noise insulation criteria. The results show that all residential dwellings, schools and
hospitals would not meet the noise insulation criteria as described in Section
4.12, and therefore, indirect technical remedies in the form of window
insulation and air conditioning would not be required.