This Section
assesses the potential noise impacts associated with the construction of the
Project in accordance with the requirements stated in Section 3.4.4 of the EIA Study Brief. It presents the potential construction
noise impacts to the identified Noise Sensitive Receivers (NSRs)
within the HKSAR.
The Project is located in a rural area in the New
Territories. The Study Area is not covered in existing
Outline Zoning Plans (OZPs), however, the major landuse
within the Study Area (i.e. within 300m from the Project Site) is of village
environs and no major commercial or industrial establishments were
identified. Access to the area is
controlled by Frontier Closed Area (FCA) Permits issued under Section 37(2) of
the Public Order Ordinance and only
limited number of vehicles with a valid permit can access to the Study Area.
Background noise levels are typical of a general rural
environment. The major existing noise sources were
identified as traffic noise from local roads.
To investigate the prevailing noise levels of the
Study Area, noise measurements were taken on 22 to 23 October 2009. The noise measurements were conducted
using a SVAN 949 Sound Level Meter (Type 1), which had been calibrated using a
SVAN Sound Level Calibrator Type 4231 with a calibration signal of 94.0 dB(A)
at 1kHz. A microphone was set at 1m
from the building façade of the Ta Kwu Ling Police
Station and it was located away from Lin Ma Hang Road and any noisy plants
within the Police Station such that the measured prevailing noise levels were
considered representative of the rural nature of the Study Area. The measurements were conducted in
accordance with the calibration and measurement procedures stated in the Technical
Memorandum on Noise From Places Other than Domestic
Premises, Public Places or Construction Sites (IND-TM). The measurement location is shown in Figure
5.1 and the measured prevailing background noise levels are summarised
in Table 5.1.
Table 5.1 Measured
Prevailing Background Noise Levels
|
Measurement
Location |
Time
Periods |
Measured
Noise Levels, dB(A) |
|
Ta Kwu
Ling Police Station |
Day-time: 17:00 to 19:00
hrs |
49 – 51 |
|
19:00
to 23:00 hrs |
46 – 49 |
|
|
|
Night-time: 03:00 to 06:00 hrs |
45 – 46 |
5.3
Relevant
Legislation and Guidelines
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
5.2.
Table 5.2 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: (a)
The
above standards apply to uses which reply on opened windows for ventilation. (b)
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 5.3.
Table 5.3 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 Country Parks or village type developments |
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)
"Country Park" means an
area that is designated as a country park pursuant to section 14 of the Country
Parks Ordinance; (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 5.4.
Table 5.4 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.
In accordance with the requirements stated in Section
3.4.4.2 of the EIA Study Brief, the Study Area for the noise impact assessment
covered an area of 300m from the boundary of the Project Site. Only the first layer of NSRs located along the Project Site boundary was included
in the assessment as the NSRs behind were located
further away from the Project Site and were screened. The area considered in the assessment is
shown in Figure
3.18.
The selected existing representative
NSRs that may potentially be affected by the
construction of the Project include Tsung Yuen Ha,
The areas adjacent to the Project Site are within the
FCA where the areas are mainly for agriculture use, village type development
and green belt.
With reference to the relevant planning
studies such as the Land Use Planning for the Closed Area, there is no planned
sensitive use within the Study
Area during the construction period, therefore
no planned NSR is identified.
The locations of the identified representative NSRs with photographs showing the NSRs
are presented in Figure
5.2.
Descriptions of the
representative NSRs are provided in Table 5.5.
Table 5.5 Representative
Noise Sensitive Receivers (NSRs)
|
NSR |
Name |
Type of Usage |
No. of Storeys |
|
HK1 |
Tsung Yuen Ha (a) |
Residential |
1 |
|
HK2 |
Chuk Yuen Village (b) |
Residential |
2 |
|
HK3 |
Kaw Liu Village |
Residential |
2 |
|
HK4 |
Kan Tau Wai |
Residential |
3 |
|
HK5 |
Ta Kwu
Ling Village |
Residential |
2 |
|
Note: (a) Assessment Point for Tsung Yuen Ha (HK1) is selected at the boundary of the
Village Zone in accordance with the development plan presented in the Land Use Planning for the Closed Area –
Feasibility Study (Agreement No. CE
60/2005 (TP)). (b) Chuk
Yuen Village (HK2) is expected to be relocated after July 2013. |
|||
5.5
Identification of Potential Impacts
Potential impacts to the NSRs during the construction phase of the Project will
mainly arise from the use of PME.
The major construction activities will include:
·
Site clearance;
·
River excavation (sediment);
·
Haul road;
·
Excavation and river training;
·
Landscaping; and
·
Reprovisioning of the boundary patrol road and boundary fence (the
advanced works).
The normal working
hours of the construction works will be between 07:00 and 19:00 hrs from Monday
to Saturday (except general holidays).
Should evening and night works between
19:00 and 07:00 hrs or on public holidays (including Sundays) be required, the
Contractor will submit a CNP application which will be assessed by the Noise
Control Authority.
Potential
Cumulative Impact from Concurrent Projects
As
indicated in Section 3.5, the Project
may interact with the following concurrent projects/studies:
·
LT/HYW
BCP and the associated works;
·
Construction
of a Secondary Boundary Fence and New Sections of Primary Boundary Fence and
Boundary Patrol Road (AEIAR-136/2009);
·
Drainage Improvement in Northern New
Territories, Package C (Remaining Works);
·
Land Use
Planning for the Closed Area (hereafter “the Closed Area Study”); and
·
New
Development Areas in North East New Territories (hereafter “the NENT NDAs Study”).
The locations of the concurrent projects
within the Study Area are indicated in Figure 3.18. Referring to Section 3.5, the potential cumulative noise impact of the Closed
Area Study and the NENT NDAs Study is yet to be
assessed since the confirmed development schedule and implementation programme
of these projects are not available at this stage. The Drainage Improvement in Northern
New Territories, Package C (Remaining Works) project is subject to another
future detailed EIA Study and detailed construction programme is not available
at this stage. The cumulative
impact cannot be assessed at this stage.
LT/HYW BCP and the Associated Works
It is anticipated that the construction of
this concurrent project will be commenced in
end 2013 and completed in end 2018.
The potential construction noise impacts due to this concurrent project have been
included in the cumulative noise impact assessment based on the
prediction results presented in the EIA Report (August 2010) for this
concurrent project. The maximum predicted noise levels at
the corresponding NSRs presented in the paper were used
in the cumulative noise impact assessment to represent the worst-case scenario.
Construction of a Secondary Boundary Fence
and New Sections of Primary Boundary Fence and Boundary Patrol Road
Section 3 of this
concurrent project (Ng Tung River to Ping Yuen River and Pak Fu
Shan to Lin Ma Hang Road) is considered as the relevant section that may have
potential cumulative noise impact to the Project. According
to the latest tentative construction programme, the construction period for Section 3 will
commence in late 2011
and complete in end 2013. Cumulative noise impacts were assessed
based on the plant inventory for Section 3 presented in the approved EIA report
(Annex
B2).
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:
·
Identify
the representative NSRs that may be affected by the
construction of the Project;
·
Determine
the plant teams for corresponding construction activities, based on the agreed
plant inventory;
·
Assign
sound power levels (SWLs) to the 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 positions of different works areas (see Annex B4);
·
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, and appropriate
utilisation rates of the PME items (Annexes B1 and B2). 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 Hong Kong market.
The works areas of the Project are shown in Figure
3.6. The total SWL
associated with each construction activity for corresponding works areas was
established. The potential noise impacts at NSRs were evaluated by comparing the predicted noise levels
with the EIAO-TM day-time
construction noise limits (Leq, 30min
dB(A)), as outlined in Section 5.3.
Advanced Works
The predicted construction noise levels
due to Advanced Works during day-time period are presented in Table 5.6. The results indicate that the
construction noise impact at NSR HK3 exceeded the EIAO-TM noise criteria during day-time period and therefore
mitigation measures will be required.
Table
5.6 Predicted
Construction Noise Levels due to Advanced Works during Day-time Period (Without
Mitigation)
|
NSR |
Description |
Predicted Construction Noise Levels(a), Leq, 30 min dB(A) |
|
HK1 |
Tsung Yuen Ha |
57 – 66 |
|
HK2 |
Chuk Yuen Village |
66 – 69 |
|
HK3 |
Kaw Liu Village |
71 – 80 |
|
HK4 |
Kan Tau Wai |
54 – 63 |
|
HK5 |
Ta Kwu Ling Village |
66 – 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. |
||
Advanced Works and River Modification
The predicted construction noise levels during
day-time period for the construction of the Project (including both River
Modification and Associated Works and Advanced Works) and concurrent projects
are presented in Table 5.7.
Summaries of the predicted noise levels and details of the noise calculations
are presented in Annexes B3
and B4, respectively.
Table
5.7 Predicted
Construction Noise Levels during Day-time Period (Without Mitigation)
|
NSR |
Description |
Predicted Construction Noise Levels(a), Leq, 30 min dB(A) |
Predicted Cumulative Construction Noise Levels(a), Leq, 30 min dB(A) |
|
HK1 |
Tsung Yuen Ha |
57 – 74 |
62 – 75 |
|
HK2 |
Chuk Yuen Village |
66 – 69 |
66 – 69 |
|
HK3 |
Kaw Liu Village |
76
– 85 |
76
– 85 |
|
HK4 |
Kan Tau Wai |
60 – 70 |
60 – 70 |
|
HK5 |
Ta Kwu Ling Village |
71 – 81 |
71 – 81 |
|
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. |
|||
The results indicate that the construction
noise impacts at NSRs HK3 and HK5 exceeded the EIAO-TM noise criteria during day-time
period due to close proximity to the construction works areas. Mitigation measures will therefore be
required for works area III and IV to mitigate the construction noise
impact.
5.8
Mitigation of Adverse Environmental Impacts
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;
·
Adoption
of movable noise barriers; and
·
Scheduling
of PME/construction activities.
Good
Site Practices
Good
site practices and noise management can considerably reduce the potential noise
impact of construction 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 construction 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 will be operated on-site and plant will be serviced
regularly during the construction phase;
·
Silencers
or mufflers on construction equipment will be utilized and will be properly
maintained during the construction phase;
·
Mobile
plant, if any, will be sited as far away from NSRs as
possible;
·
Machines
and plant (such as trucks) that may be in intermittent use will be shut down
between work periods or will be throttled down to a minimum;
·
Plant
known to emit noise strongly in one direction will, wherever possible, be
orientated so that the noise is directed away from the nearby NSRs; and
·
Material
stockpiles and other structures will be effectively utilised, wherever
practicable, in screening noise from on-site construction activities.
Use
of Quiet PME
The
use of quiet PME is considered to be a practicable means to mitigate the
construction noise impact in both works areas III and IV. 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
5.8.
Table 5.8 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 |
|
Dozer |
BS
C3/65 |
111 |
|
Concrete
pump |
BS
C6/36 |
106 |
|
Lorry |
EPD
QPME (a) |
105 |
|
Note: (a) “Sound power levels
of other commonly used PME” prepared by the Noise Control Authority
(http://www.epd.gov.hk/epd/english/application_for_licences/guidance/files/OtherSWLe.pdf
) |
||
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 in works areas III and IV, 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 m-2 and have no openings or gaps.
Scheduling
of PME/Construction Activities
To further alleviate the
construction noise impacts, some construction activities in works area III will
be operated in sequence rather than simultaneously within the respective works
sites, ie only Group A, Group B or Group C of PMEs should be operated at any time (see Annex B5).
The above mitigation measures have
been vetted and confirmed by the Project Proponent/Design Engineer as being
practicable in completing the works within the scheduled timeframe. It is considered practical to specify
the quiet PME and noise mitigation measures described above in the contract
document to mitigate the construction noise impact.
With
the implementation of the good construction site practices, use of quiet PME
and movable noise barriers in works areas III and IV and scheduling of
PME/construction activities in works area III (as shown in Annex B5), the mitigated noise levels due to the
construction of the Project and concurrent projects were calculated at the
representative NSRs with results summarised in Table 5.9. Summaries of predicted mitigated noise
levels and detailed calculations are presented in Annexes B6 and B7, respectively.
Table 5.9 Predicted
Construction Noise Levels during Day-time Period (With Mitigation)
|
NSR |
Description |
Predicted Construction Noise Levels(a), Leq, 30 min dB(A) |
Predicted Cumulative Construction Noise
Levels(a), Leq, 30 min dB(A) |
|
HK3 |
Kaw Lui
Village |
65
– 75 |
65
– 75 |
|
HK5 |
Ta Kwu
Ling Village |
60
– 70 |
61
– 74 |
|
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
in works areas III and IV, no exceedance of the EIAO-TM noise criteria during the
construction phase is anticipated at NSRs HK3 and
HK5. No further mitigation will therefore be required.
Advanced
Works
With
the implementation of the mitigation measures, the predicted construction noise
levels during the advanced works indicate no exceedance
of the EIAO-TM day-time noise
criterion and therefore no further mitigation measures will be required.
5.9
Residual Environmental Impacts
With
the implementation of the recommended noise mitigation measures, the cumulative
predicted noise levels due to the Project and the concurrent projects during
construction phase would comply with the EIAO-TM
day-time noise criterion. No
residual impact is anticipated.
5.10
Monitoring and Audit Requirements
Noise monitoring is recommended during the
construction phase to ensure compliance with the noise criterion at the
representative NSRs. Weekly noise monitoring will be
undertaken at the representative NSRs (HK3 Kaw Liu
Village and HK5 Ta Kwu Ling Village) during
construction at Works Area III and IV of the River Modification and Associated
Works. Monthly site audits will be
conducted for both Advanced Works and River Modification and Associated Works
to ensure that the recommended mitigation measures are properly implemented
during the construction stage.
Details of the noise monitoring requirements are presented in the
EM&A Manual.
Owing to the close proximity of some of the NSRs to the works areas of the Project, mitigation measures
are required to be implemented to mitigate the construction noise impacts. Practicable mitigation measures,
including good construction site practices, use of quiet PME, movable noise
barriers and scheduling of PME/construction activities, are recommended. With the implementation of mitigation
measures, the mitigated construction noise levels at the representative NSRs will comply with the construction noise criterion of
75 dB(A) throughout the construction period. Noise monitoring during the construction
stage is recommended to ensure compliance with the relevant noise
criteria.