4.1.1
This
section presents an assessment on the potential noise impacts arising from the
proposed Project. During the Stage 1 works period before 2012, based on the
latest available information, the existence of planned noise sensitive
receivers (NSRs) at the former
4.2
Environmental Legislation, Policies, Plans, Standards and Criteria
General
4.2.1
Noise
impacts have been assessed in accordance with the criteria and methodology
given in the Technical Memoranda (TMs) under the Noise Control Ordinance (NCO),
and the Technical Memorandum on Environmental Impact Assessment Process
(EIAO-TM).
4.2.2
The
NCO and EIAO provide the statutory framework for noise control. Assessment procedures and standards are
set out in five TMs listed below:
l
EIAO-TM
l
TM
on Noise from Construction Work other than Percussive Piling (GW-TM)
l
TM
on Noise from Percussive Piling (PP-TM)
l
TM
on Noise from Construction Work in Designated Areas (DA-TM)
l
TM
on Noise from Places other than Domestic Premises, Public Places or
Construction Sites (IND-TM)
Construction Noise – General
Construction
4.2.3
The NCO provides the statutory framework for noise
control of construction work other than percussive piling using powered
mechanical equipment (PME) between the hours of 1900 and 0700 hours or at any
time on Sundays and general holiday (that is, restricted hours). Noise control on construction activities
taking place at other times is subject to the Criteria for Evaluating Noise
Impact stated in Table 1B of Annex 5 in the EIAO-TM. The noise limit is Leq (30 minutes)
75 dB(A) at the façades of dwellings and 70 dB(A) at the façade of
schools (65 dB(A) during examinations).
4.3
Project Description and Construction Activities
4.3.1
The
Project involves dredging at the existing seawall at the southern tip of the
former
4.3.2
In
accordance with the construction programme of the Project, dredging works would
be carried out in two stages covering different areas as indicated in Figure 4.1A.
4.3.3
The
construction activities under Stage 1 would be completed before Year 2012. The construction activities under Stage
2 (dredging activities for the second berth) are currently tentatively
scheduled to commence in Year 2012 or later. The programme for Stage 2 dredging is
indicative only and the actual programme would depend on the commissioning
programme for the second berth.
4.3.4
As
mentioned in Section 2, maintenance dredging is required once every 5 to 10
years during the operation stage of the proposed cruise terminal.
4.4.1
In
order to evaluate the construction noise impacts from the Project,
representative Noise Sensitive Receivers (NSRs) within the Study Area are
identified for assessment. The area
for the noise impact assessment includes all areas within 300 m from the
Project boundary. There are no
existing NSRs identified within 300 m from the boundary of the proposed
dredging areas. Based on the latest
available information, existence of planned NSRs at the former
4.4.2
As
there is no available information on the commissioning year of the planned
residential developments at the former Kai Tak Airport runway, as a
conservative assumption for the purpose of this assessment, a planned hotel and
two planned residential R3 sites which are located within 300m from the
dredging works area are assumed to be occupied during the dredging period. The two planned residential R3 sites are
the nearest residential sites to the Stage 2 dredging area. As the planned hotel would be provided with
central air conditioning and would not rely on openable windows for
ventilation, adverse construction noise impact at the planned hotel is not
anticipated. Therefore, only the
two planned residential sites are taken as NSRs during the dredging works period
for the purpose of a conservative assessment. Table 4.1 summarises the
representative NSRs for construction noise impact assessment for the Stage 2
dredging. The locations of the
assessment points for these NSRs are shown in Figure 4.1. These two selected assessment
points have been agreed with EPD on 14 March 2007 according to Section 3.4.6.2
item (iii) (b) of the EIA Study Brief No. ESB-159/2006.
Table 4.1 RepresentativeNoise
Sensitive Receivers for Construction Noise Impact Assessment for Stage 2 Dredging
|
NSR |
Description |
Use |
Maximum
Height* (mPD) |
|
N1 |
Planned Residential Development (R3 site) |
Residential |
45 |
|
N2 |
Planned Residential Development (R3 site) |
Residential |
55 |
Note: * Information
on the number of floors of the planned development is not available at this
stage, only maximum height of the development is provided.
4.5.1
The
proposed dredging works is scheduled to be commenced in Year 2009 and to be completed
in 2013. According to the
construction programme, there are two work stages. Stage 1 works (Year 2009 – Year 2011)
include dredging activities to facilitate the operation of the first
berth. Stage 2 works (Year 2012 –
Year 2013) include dredging activities for the second berth. The programme for Stage 2 dredging is
indicative only and the actual programme would depend on the commissioning
programme for the second berth. The
locations of dredging areas are indicated in Figure 4.1.
4.5.2
All
dredging activities including maintenance dredging are planned to be carried
out during 0700 to 1900 hours (Monday to Saturday excluding general
holidays). No dredging works would
be carried out during restricted hours.
4.5.3
Any
construction activities taking place concurrently within 300m of a given NSR
are considered to contribute to the cumulative impact at that NSR. With regard to concurrent projects, the
construction works for two building sites of the Kai Tak Development might
occur simultaneously with the Stage 2 dredging activities. One building site would be in the
immediately south of NSR N1 namely the Tourism Node at the southern tip of the
former
4.5.4
In
accordance with the EIAO-TM, the methodology outlined in the GW-TM has been
used for the assessment of construction noise (excluding percussive
piling). Sound Power Levels (SWLs)
of the equipment were taken from Table 3 of this TM. Schedules of powered mechanical
equipment (PME) for different construction tasks of the Project and other
concurrent construction activities of other projects during normal daytime
working hours are presented in Appendix
4.1. As a worst case
scenario, on-time percentage for all PME of each construction activity is
assumed to be 100%. Letter from Project
Proponent confirming that the plant inventory is valid for the Project works is
attached in Appendix 4.3.
4.5.5
It
was assumed that all PME items required for a particular construction activity
would be located at the notional or probable source position of the segment
where such activity is to be performed.
The assessment is based on the cumulative SWL of PME likely to be used
for each location, taking into account the construction period in the vicinity
of the receiver location. To
predict the noise level, PME was divided into groups required for each discrete
construction task. The objective
was to identify the worst case scenario representing those items of PME that
would be in use concurrently at any given time. The sound pressure level of each
construction task was calculated, depending on the number of plant and distance
from receivers. The noise levels at
NSRs are then predicted by adding up the SWLs of all concurrent construction
tasks.
4.5.6
A
positive 3 dB(A) façade correction was added to the predicted noise levels in
order to account for the facade effect at each NSR.
4.6
Identification of Environmental Impacts
4.6.1
In
order to evaluate the construction noise impacts from the Project,
representative NSRs within the Study Area are identified for assessment. As mentioned in Section 4.4 above, there
are no existing NSRs or planned NSRs located within 300m from the Project
boundary during the Stage 1 works period.
The nearest NSRs are located at more than 500m away from the Stage 1
work site, therefore, no adverse impact arising from the Stage 1 dredging works
and seawall reconstruction would be expected.
4.6.2
During
the Stage 2 works period, potential construction noise impact arising from the Project
on the two planned residential developments at the former
4.6.3
During
operation stage of the proposed cruise terminal, regular maintenance dredging
would be carried out once every 5 to 10 years. Potential noise impact arising from
dredging would be expected on the nearest noise sensitive receivers.
4.7
Prediction and Evaluation of Environmental Impacts
4.7.1
During
the Stage 2 works period, no exceedance of the construction noise criteria
(Leq(30 minutes) 75 dB(A)) for residential uses are predicted
at the representative NSRs in the absence of mitigation measures during normal
daytime working hours. Details of
the construction noise calculations and results are presented in Appendix 4.1. Results show that the predicted noise
levels related to the concurrent construction works of the Project and two
building construction projects are in the range of 72
to 74 dB(A). A summary of
the unmitigated construction noise levels at the representative NSRs during
normal daytime working hours within the construction period of the Project is
listed in Table 4.2.
Table 4.2 UnmitigatedConstruction
Noise Levels at Representative NSRs during
|
Representative NSRs |
Predicted Unmitigated Construction Noise
Levels during |
|
N1 |
73 – 74 |
|
N2 |
72 – 73 |
4.7.2
During
operation stage of the proposed cruise terminal, maintenance dredging would be
carried out once every 5 to 10 years.
As a conservative impact assessment, maintenance dredging is assumed to be
carried out at the manoeuvre basin for berth 2 which is nearer to the
NSRs. The plant to be used in
maintenance dredging would include one grab dredger, one derrick lighter and
one tug boat. Details of noise
calculation and results are presented in Appendix 4.2. Results indicate that the predicted
noise levels would be in the range of 59 – 60 dB(A) during maintenance
dredging. The NSRs are expected to
comply with the construction noise criterion of 75 dB(A).
4.8
Evaluation of Residual Environmental Impacts
4.8.1
The
construction noise levels at all representative residential NSRs are predicted
to comply with the noise standards stipulated in the EIAO-TM without
implementation of mitigation measures.
4.8.2
In order to further ameliorate the construction noise
impacts, good site practices listed below should be adopted by all the
Contractors as far as practicable.
Although the noise mitigating effects are not easily quantifiable and
the benefits may vary with the site conditions and operating conditions, good
site practices are easy to implement and do not impact upon the works schedule.
l
Only
well-maintained plant should be operated on-site and plant should be serviced
regularly during the construction program.
l
Mobile
plant, if any, should be sited as far away from nearby NSRs as possible.
l
Machines
and plant (such as trucks) that may be in intermittent use should be shut down
between works periods or should be throttled down to a minimum.
l
Plant
known to emit noise strongly in one direction should, wherever possible, be
orientated so that the noise is directed away from nearby NSRs.
l
Material
stockpiles and other structures should be effectively utilised, wherever
practicable, in screening noise from on-site construction activities.
4.9
Environmental Monitoring and Audit
4.9.1
If
there are any planned NSRs within 300 m from the works area occupied during the
dredging period, an EM&A programme should be implemented during the
period(s) with predicted occurrence of noisy activities. All the recommended mitigation measures
for daytime normal working activities should be incorporated into the EM&A
programme for implementation during dredging. Details of the EM&A requirement are
provided in the EM&A Manual.
4.10.1
This assessment has predicted the construction noise
impacts of the Project during normal daytime working hours, taking into account
other concurrent projects within a
4.10.2
Assessment on noise impact from maintenance dredging was
also conducted. Results indicated
that the predicted noise at the nearest NSRs would comply with the construction
noise criterion of 75 dB(A).