5.1.1
Potential noise impacts during
the construction and operational phases of the Project have been evaluated and
mitigation measures have been recommended where necessary and appropriate in
this section.
5.2.1
The land use in the Study Area
is mainly residential, with existing low-rise villages such as Lung Wo Tsuen and Tan Shan Tsuen and planned housing developments
within the Anderson Road Quarry Main Site. The existing noise climate is
dominated by road traffic noise from Clear Water Bay Road.
5.4.2
With reference to the latest Outline Zoning Plans (OZP), Tseng Lan Shue
Outline Zoning Plan (No. S/SK-TLS/8) dated March 2006 and Kwun Tong North OZP
(Plan No. S/K14N/13) dated September 2010, existing and planned NSRs including
domestic premises and educational institutions within the Study Area are
identified following the requirement of Annex 13 to the EIAO-TM.
5.4.3
For the purpose of the noise
assessment, a number of representative assessment points are selected which are
considered to be potentially worst-affected NSRs. The NSRs for noise
assessments are summarised in Table 5.1 and their locations are
illustrated in Figure 5.1. Photographs of all the identified existing
NSRs are provided in Appendix 5.1.
Table 5.1 Representative NSRs for Noise
Impact Assessment within the Study Area
Noise Sensitive Receivers
(NSR)
|
Existing / Planned Land Use
|
Description
|
Approx. Setback Distance (m)
|
Construction Phase [1]
|
NLWT-01 [2]
|
Existing Residential
|
Lung Wo Tsuen
|
>200
|
CYCS-01 [2]
|
Existing Residential
|
Chi Yum Ching She
|
>200
|
TSV-01 [2]
|
Existing Residential
|
Tan Shan Tsuen
|
>250
|
Operational Phase [2]
|
R2-1-R006 [1]
|
Planned Residential
|
Private Housing, ARQ Site R2-1
|
80
|
R2-2-R013 [1]
|
Planned Residential
|
Private Housing, ARQ Site R2-2
|
195
|
Notes:
[1] Based on the approved Schedule
3 EIA Report for Development of Anderson Road Quarry (and subsequent review
exercise), the intake year for NSRs ARQ R2-1 and R2-2 would be in the time
frame of Year 2026, whereas the construction of rock cavern would be completed
by 2020. There is no overlap between the occupation of NSRs ARQ R2-1 and R2-2
and the construction works.
[2] For the operational fixed plant noise
assessment, the selected assessment points are ARQ Private Housing Sites (ID:
R2-1-R006 and R2-2-R013). These two NSRs would be closest to the rock cavern
development for the operational phase assessment. Other existing NSRs (ID: NLWT-01, CYCS-01 and
TSV-01) are much further away and completely shielded by the hill in between.
NSR ID: R2-1-R006 and R2-2-R013 at Private Housing Site would experience the
worst impacts from the fixed noise sources, and therefore the recommended noise
mitigation measures for fixed noise sources should be formulated (by backward
calculation) based on these selected assessment points at ARQ Private Housing
Site.
Construction Phase
Construction Noise during Non-restricted Hours
5.5.1 The potential sources of noise impacts during the construction phase
of the Project would mainly be the use of Powered Mechanical Equipment (PME)
for various construction activities.
Major construction works would include site clearance, portal slopes
excavation and stabilisation works, cavern excavation and temporary
installation, permanent cavern (and adits) lining
construction. The construction programme is shown in Table 5.2.
Table 5.2 Construction
Programme for Cavern Development
Works Activity for Museum Cavern Development
|
Anticipated Start
|
Anticipated End
|
Mobilization and Site Clearance
|
Jan-2018
|
Mar-2018
|
Slopes Excavation and Stabilisation
|
Apr-2018
|
Jul-2018
|
Cavern Excavation
|
Aug-2018
|
May-2019
|
Permanent Cavern and Adits Lining
Works
|
Jun-2019
|
Oct-2019
|
Landscaping & Finishing Works
|
Nov-2019
|
Jan-2020
|
Construction Noise during Restricted Hours
5.5.2 Based on the currently envisaged construction programme, no
construction works during restricted hours will be required under normal
circumstances.
Cumulative Construction Noise
Impacts from Other Concurrent Projects
5.5.3 Some concurrent construction works/projects within the Study Area
may have an interface with the Project. These are listed below and their locations are
illustrated in Appendix 5.2:
Site Formation and Engineering
Infrastructure Works at Main Site of Anderson Road Quarry Main Site - Phase 2
area (Worksites S11a, S11b, S12a, S12b, S12c, S13a, S13b & S13c);
Construction of Drainage
Retention Tank (Worksite S21b);
Construction of Viewing
Platform (Worksite S26c); and
Foundation and Superstructure
Works of Service Reservoirs and Pumping Station (Worksites S31a & S31b).
5.5.4 As the worksite of the road improvement works at the junction of
Clear Water Bay Road and On Sau Road (Item 5 of the road improvement works
described in Section 2.3.2) is located outside the Study Area of the Project,
it is not included as a concurrent noise source for the construction phase
assessment.
Operational Phase
5.5.5 The potential operational noise impact is associated with the fixed
plant noise sources such as the ventilation shaft proposed at the cavern museum
development.
General
5.6.1 Noise impacts were assessed in accordance with the relevant criteria
stipulated in the Technical Memorandum on Environmental Impact Assessment
Process (EIAO-TM).
Construction Phase
5.6.2 As indicated in Section 5.5.2, no construction works will be
required during restricted hours. On
this basis, the criteria stipulated in Table 1B of Annex 5 to the EIAO-TM,
namely Leq(30 minutes) 75 dB(A)
at the façades of dwellings and 70 dB(A) at the façades of schools (65 dB(A)
during examinations), are applicable to the assessment of construction noise
impacts.
Operational Phase - Fixed Plant Noise
5.6.3 The criterion for fixed plant
noise is stipulated in Table 1A of Annex 5 to the EIAO-TM, which in turn makes
reference to Table 3 of the Technical Memorandum for the Assessment of Noise
from Places Other than Domestic Premises, Public Places or Construction Sites (IND-TM) issued under the NCO. The applicable noise
criterion for a particular NSR, which varies with respect to the Area Sensitive
Rating (ASR) of that NSR and the time of the day, is 5 dB(A) below the
Acceptable Noise Level (ANL - 5 dB(A)), as presented in Table 5.3, or the prevailing background noise level, whichever is lower. For the assessment of impacts from fixed
noise sources in this EIA, the ASR is determined based on the best available
information at this stage of the Project.
Nothing in this assessment would bind the Noise Control Authority in the
context of law enforcement against any fixed sources being assessed.
Table 5.3 Fixed
Plant Noise Criteria/ Design Target
Time
Period
|
Fixed
Plant Noise for Different Area Sensitivity Rating,
(Leq 30
min, dB(A))
|
ANL,
dB(A)
|
ANL-5,
dB(A) [see Note]
|
ASR A
|
ASR B
|
ASR C
|
ASR A
|
ASR B
|
ASR C
|
Day
(0700 to 1900 hrs)
|
60
|
65
|
70
|
55
|
60
|
65
|
Evening
(1900 to 2300 hrs)
|
60
|
65
|
70
|
55
|
60
|
65
|
Night
(2300 to 0700 hrs)
|
50
|
55
|
60
|
45
|
50
|
55
|
Note:
The ultimate noise
criterion should be 5dB(A) below the Acceptable Noise
Level (ANL-5dB(A)) or the prevailing background noise level, whichever is
lower.
Construction Phase
5.7.1 The primary source of potential noise impact from the construction
works is the use of powered mechanical equipment on site. The construction
activities would involve excavation and associated works which have the
potential to pose adverse noise impacts to the surrounding NSRs.
5.7.2 As the major construction activity would be mechanical excavation,
it would not cause adverse structure-borne noise. The nearest NSRs at ARQ Site R2-1 and Site
R2-2 are also located at more than 200m from the cavern site on the other side
of the hill and adverse structure-borne impacts are considered extremely
unlikely with such a large setback distance.
Operational Phase
5.7.3 Fixed plant noise from the ventilation shafts of the cavern would be
the major source of noise impacts, if any, during the operational phase.
Construction Phase
5.8.1 A construction plant inventory is first developed based on the
engineering design and construction programme.
Construction noise impacts on the representative NSRs within the Study
Area are assessed in accordance with the methodology stipulated in Annex 13 to
the EIAO-TM.
5.8.2 The procedures for the construction noise assessment are summarized
as follows:
Locate the NSRs which would
most likely be affected by noise from the construction work;
Determine the items of PME for
each discrete construction activity, based on available information or agreed
plant inventories;
Assign sound power levels
(SWLs) to the proposed PME ;
Calculate distance attenuation
to NSRs from notional noise source;
Apply corrections in the
calculations such as potential screening effects and acoustic reflection, if
any;
Predict construction noise
levels at NSRs in the absence of any mitigation measures;
Consider cumulative impact from
other concurrent works/projects, if any, within the Study Area; and
Compare the cumulative noise
level against the noise criterion and propose suitable mitigation measures.
5.8.3 For the SWLs of PME, reference is made to Table 3 of the Technical
Memorandum on Noise from Construction Work other than Percussive Piling
(GW-TM). Groups of PME have been assigned for the various activities
anticipated for the construction of the Project. The proposed plant inventory for the
construction of the Project has been provided by the Preliminary Design
Consultants of the Project Proponent.
According to Section 4.2 in
the EIAO Guidance
Note No. 9/2010 “Preparation of Construction Noise Impact
Assessment Under the EIAO” (GN 9/2010), reduction of percentage on-time is
not a viable mitigation measures for PME and it should never be considered as a
direct way to mitigate construction noise impacts after the assessment found
exceedance in the unmitigated construction noise levels. Nonetheless, the
application of percentage on-time is still considered reasonable to reflect the
actual situation for some PME which only stays on for a short period in 30
minutes, for example, concrete lorry mixer in the case of concreting and dump
truck in the case of disposal of excavated materials from roadside, and
therefore has been used as the basic assumption for those specific types of PME
in the assessment. The feasibility,
practicability and reasonableness for the proposed plant inventory and
associated plant utilisation rates adopted for the assessment have been
confirmed by the Project Engineer responsible for the design and supervision of
construction works of the Project.
Operational Phase -
Fixed Plant Noise
5.8.4 Representative NSRs within the Study Area are identified for the
assessment. For this assessment, standard acoustic principles are applied.
5.8.5 As noise specifications of the proposed fixed plant in this Project
are not available for the EIA Study, the maximum permissible sound power levels
of fixed plant (Max. SWLs) are determined for future detailed engineering
design to ensure compliance with the relevant noise criteria. Cumulative
impacts from potential concurrent fixed noise sources such as the pumping
station located within the Study Area are considered with reference to the
approved EIA report for Development of Anderson Road Quarry (EIAO Register No.:
AEIAR-183/2014).
5.8.6 The following formula is used for calculating the Max. SWL:
SPL = Max. SWL – DC + FC + TC
- BC
where
SPL
|
Sound Pressure Level, in dB(A)
|
Max. SWL
|
Maximum Permissible Sound Power
Level, in dB(A)
|
DC
|
Distance Attenuation, in dB(A)
(i.e. 20 log D + 8 [where D is the distance in metres])
|
FC
|
Facade Correction, in dB(A)
(i.e. 3 dB(A))
|
TC
|
Tonal Correction, in dB(A)
|
BC
|
Barrier Correction, in dB(A)
|
5.8.7 It is assumed that all the fixed plant noise sources would be
operated at the same time with no noise barrier screening correction for a
conservative assessment of the worst-case scenario.
5.8.8 The fixed noise sources
associated with the Project should be free of the characteristics of tonality,
impulsiveness and intermittency. If any tonality, intermittency or impulsiveness characteristics
are identified during the detailed
design or the commissioning of the plant, the Max
SWL should be reduced in accordance with the applicable correction factors, in
the range of 3 to 6 dB(A), as prescribed in Section
3.3 of the IND-TM.
5.9
Prediction and Evaluation
of Environmental Impacts
Construction Phase
5.9.1 The plant inventory and associated utilisation rates in Appendix
5.2, which have been reviewed and confirmed by the Project Engineer
responsible for the design and supervision of construction works of the Project,
are adopted for the construction noise assessment. The following key features
have been considered during the design of the Project to alleviate the
construction noise impacts as far as practicable:
Minimisation of the number of
PME to be deployed; and
Grouping of PME adopted for the
same construction activities, where practicable, in order to reduce the
construction noise emission due to concurrent use of PME.
5.9.2 The unmitigated noise levels at representative NSRs are predicted
and presented in Table 5.4 based on the construction programme and plant
inventory in Appendix 5.2.
Locations of notional sources and distance to NSRs are also shown in Appendix
5.2. The percentage on-time for the
PME has been reviewed and confirmed by the Project Engineer responsible for the
design and supervision of construction works of the Project to be reasonable.
Table 5.4 Cumulative
Unmitigated Construction Noise Levels (Non-restricted Hour)
NSR ID
|
Description
|
Predicted Unmitigated Construction Noise Levels, dB(A)
|
EIAO-TM Noise Criteria, dB(A)
|
Exceedance of EIAO-TM Noise Criteria? (Y/N)
|
TSV-01
|
Tan Shan Tsuen
|
61 – 70
|
75
|
N
|
NLWT-01
|
Lung Wo Tsuen
|
62 – 71
|
75
|
N
|
CYCS-01
|
Chi Yum Ching She
|
63 – 72
|
75
|
N
|
5.9.3 The predicted noise levels at the representative NSRs range from 61 to
72 dB(A). No exceedances are predicted at the NSRs and
no specific construction noise mitigation measures will be required. Nonetheless, to minimize noise impacts on the
surrounding environment, the future contractors are recommended to follow the noise
control requirements set out under the "Recommended Pollution Control
Clauses for Construction Contracts” published by the Environmental Protection
Department (EPD).
5.9.4 The location of fixed plant noise sources and NSRs are shown in Appendix
5.3. The worst-affected NSRs are identified to be planned private housings
at Site R2-1 and Site R2-2 at the Anderson Road Quarry Main Site. Representative
assessment points at Site R2-1 (NSR ID R2-1-R006) and Site R2-2 (NSR ID
R2-2-R013), which are about 80m and 195m respectively from the Project works
boundary, are selected and depicted in Appendix 5.3.
5.9.5 As the fixed plant noise criteria at the selected assessment points
depend on the prevailing noise level, prevailing noise measurement results in the
approved EIA report for Development of Anderson Road Quarry (EIAO Register No.:
AEIAR-183/2014) are adopted in the determination of the noise criteria as
detailed in Appendix 5.3. The Max. SWLs for the
ventilation shaft, derived based on the methodology described in Section 5.8,
for Day/Evening time (0700 to 2300 hours) and Night time (2300 to 0700 hours)
are presented in Table 5.5.
Table 5.5 Fixed
Plant Noise Design Criteria for Ventilation shaft
Time Period
|
Maximum Permissible Sound Power Level (Leq, 30min, dB(A)) [a] [b] [c]
|
Exhaust at the Ventilation Shaft
|
Day and Evening
(0700 to 2300 hours)
|
93
|
Night
(2300 to 0700 hours)
|
86
|
Notes:
[a] The maximum
permissible SWLs were obtained based on an assumed tonal correction factor of
3dB(A). The tonal correction factor to be adopted for the actual equipment
should be determined according to Section 5.8.8 and 5.9.6.
[b]
If any tonality, intermittency or
impulsiveness characteristics are identified for the fixed plant during its
detailed design or commissioning, the noise design limit should be reduced to cater
for these corrections in accordance with the IND-TM.
[c]
Maximum Allowable SWL (Day and Evening /
Night) of Ventilation Shaft of Proposed Rock Cavern at +200mPD be subject to
change pending confirmation of exact location of the Ventilation Shaft in the
detailed engineering design.
5.9.6 In addition, the equipment should be free of the characteristics of
tonality, impulsiveness and intermittency. If any tonality, impulsiveness and
intermittency characteristics are identified for the equipment during the
detailed design or the commissioning, the Max SWL should be reduced to cater
for the relevant correction factors as prescribed in Section 3.3 of IND-TM.
5.9.7 If there is any change in engineering design information during the detailed
design stage or the fitting-out stage, the fixed plant noise design should also
be reviewed by engineer/contractor to ensure that both the relevant noise criteria
can still be met at the NSRs.
Construction Phase
5.10.1 The construction noise assessment indicates that there would be no exceedance
of the construction noise criteria at the representative NSRs even without any
mitigation measures. Notwithstanding the
above, the future contractors should follow the requirements set out in the “Recommended
Environmental Pollution Control Clauses” published by EPD and adopt good site practice outlined below to minimise
construction noise impacts on the surrounding environment.
Good Site Practice
5.10.2 Good site practices are easy to implement and do not impact upon the
works schedule. The site practices
listed below 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 phase;
Silencers or mufflers on construction equipment should be utilized and
should be properly maintained during the construction phase;
Mobile plant, if any, should be sited as far 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;
and
Material stockpiles and other structures should be effectively utilized,
wherever practicable, in screening noise from on-site construction activities.
5.10.3 With the fixed plant properly designed to meet the maximum permissible
SWL in Table 5.5, no operational phase noise impacts are anticipated. The
following noise reduction measures are recommended to be considered as far as
practicable during the detailed design and procurement stages:
Choose quieter plant;
Include noise levels
specification when ordering new electro-mechanical equipment for the
ventilation system;
Locate fixed plant/louvres away
from any NSRs as far as practicable;
Locate fixed plant in walled
plant rooms or in specially designed enclosures;
Locate noisy machines in a
basement or a completely separate building;
Install direct noise mitigation
measures including silencers, acoustic louvres and acoustic enclosure where
necessary; and
Develop and implement a regularly
scheduled plant maintenance programme so that equipment is properly operated
and serviced in order to maintain controlled level of noise. The programme should be implemented by
properly trained personnel.
5.11.1 The assessment has not found any excessive residual noise impacts
for both the construction and operational phases of the Project.
5.12.1 As the Project would not result in any adverse construction noise
impacts, construction phase noise monitoring is considered not necessary.
Construction Phase
5.13.1 Noise impacts arising from the construction activities of the Project
have been assessed for NSRs in the Study Area.
Cumulative unmitigated construction noise levels at the representative
NSRs are predicted to be in the range of 61 to 72 dB(A),
which comply with the construction noise criterion of 75 dB(A). No adverse
construction noise impact is therefore anticipated.
5.13.2 To minimise noise impacts on the surrounding environment, the future
contractors are recommended to follow the noise control requirements set out
under the "Recommended Pollution Control Clauses for Construction
Contracts” published by EPD.
Operational Phase
5.13.3 The maximum permissible SWLs for the ventilation shaft of the cavern
have been derived as noise design target. With the selection of suitable plant equipment
and adoption of appropriate acoustic treatment in accordance with the design
target SWL, the NSRs would not be adversely affected by the noise generated
from the operation of the ventilation shaft.
5.13.4 If there is any change in engineering design information during
detailed design stage or fitting-out stage, the fixed plant design should be
reviewed by engineer/contractor to ensure that the noise criteria should still
be met at the NSRs.