3.1.1
Noise impact is likely to arise
from some of the activities during construction phase of the Project. The EIA
recommended a number of mitigation measures that should be implemented to
reduce potential impacts to acceptable limits. A monitoring programme is
recommended for baseline conditions and during the construction phase to
evaluate the performance of the proposed measures.
3.1.2
This section of the Manual
lists all the recommended mitigative and preventive measures in the EIA for the
control of construction noise, and the requirements for baseline and construction
phase noise monitoring.
3.2.1
The
construction noise level shall be measured in terms of the A-weighted
equivalent continuous sound pressure level (Leq). Leq(30 min) shall be used as
the monitoring parameter for the time period between 0700-1900 hours on normal
weekdays.
3.2.2
As
supplementary information for data auditing, statistical results such as L10
and L90 shall also be obtained for reference. A sample data record
sheet is shown in Appendix B for reference.
3.3.1
As
referred to in the Technical Memorandum (TM) issued under the Noise Control
Ordinance (NCO), sound level meters in compliance with the International
Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type
1) specifications shall be used for carrying out the noise monitoring.
Immediately prior to and following each noise measurement, the accuracy of the
sound level meter shall be checked using an acoustic calibrator generating a
known sound pressure level at a known frequency. Measurements may be accepted
as valid only if the calibration level from before and after the noise
measurement agree to within 1.0 dB.
3.3.2
Noise
measurements shall not be made in the presence of fog, rain, wind with a steady
speed exceeding 5ms-1 or wind with gusts exceeding 10ms-1.
The wind speed shall be checked with a portable wind speed meter capable of
measuring the wind speed in ms-1.
3.3.3
The
ET Leader is responsible for the provision of the monitoring equipment. He
shall ensure that sufficient noise measuring equipment and associated
instrumentation are available for carrying out the baseline monitoring, regular
impact monitoring and ad hoc
monitoring. All the equipment and associated instrumentation shall be clearly
labelled.
3.4.1
The
locations of noise monitoring stations are shown in Table 3.1 and Figures 3.1 –
3.3. In case works is required for
restricted hours, monitoring locations may also include those relevant to the
application of Construction Noise Permit (CNPs) as advised by EPD.
3.4.2
The
status and locations of noise sensitive receivers may change after issuing this
manual. In this case, the ET Leader shall propose updated monitoring stations
and seek approval from ER and agreement from the ICE and EPD of the proposal.
Noise
Monitoring Stations for Baseline and Construction Monitoring
|
Noise Monitoring Stations |
Equivalent RNSRs in EIA |
Representative for |
|
MUP-N1 |
MUP05-2 |
Village north of Loi
Tung |
|
MUP-N2 |
MUP05-4 |
Village north of Loi
Tung |
|
MUP-N3 |
MUP05-6 |
Village north of Loi
Tung |
|
MUP-N4 |
MUP04A-2 |
Village house near Loi
Tung |
|
LMH-N1* |
LMH01-1, LMH01-2,
LMH01-3, LMH01-4 or LMH01-5 |
|
Notes:
* Mobile station subject to
the location of the construction works and to be proposed by the ET Leader.
3.4.3
When
alternative monitoring stations are proposed, the monitoring locations should
be chosen based on the following criteria:
(a)
at
locations close to the major site activities which are likely to have noise
impacts;
(b)
close
to the noise sensitive receivers (N.B. For the purposes of this section, any
domestic premises, hotel, hostel, temporary housing accommodation, hospital,
medical clinic, educational institution, place of public worship, library,
court of law, performing art centre should be considered as noise sensitive
receiver); and
(c)
for
monitoring locations located in the vicinity of the sensitive receivers, care
should be taken to cause minimal disturbance to the occupants during
monitoring.
3.4.4
The
monitoring station shall normally be at a point 1m from the exterior of the
sensitive receivers building facade and be at a position 1.2m above the ground.
If there is problem with access to the normal monitoring position, an
alternative position may be chosen, and a correction to the measurements shall
be made. For reference, a correction of +3dB(A) shall be made to the free field
measurements.
3.4.5
The
ET Leader shall agree with the ER and IEC on the monitoring position and the
corrections adopted. Once the positions for the monitoring stations are chosen,
the baseline monitoring and the impact monitoring shall be carried out at the
same positions.
3.5.1
The
ET Leader shall carry out baseline noise monitoring prior to the commencement
of the construction works. The baseline monitoring shall be carried out
continuously for a period of at least two weeks (14 consecutive days) at
interval of 5 minutes. The A-weighted noise level Leq, L10 and L90 shall be recorded.
A schedule on the baseline monitoring shall be submitted to the ER and IEC for
approval before the monitoring starts.
3.5.2
There
shall not be any construction activities in the vicinity of the stations during
the baseline monitoring. In exceptional cases, when insufficient baseline
monitoring data or questionable results are obtained, the ET Leader shall
liaise with IEC to agree on an appropriate set of data to be used as a baseline
reference and submit to the EPD for approval.
3.6.1
Noise
monitoring shall be carried out at all the designated monitoring station in
Table 3.1 during the construction phase of the project. The monitoring
frequency shall depend on the scale of the construction activities. The
following is an initial guide on the regular monitoring frequency for each
station on a per week basis when noise generating activities are underway:
•
one
set of Leq (30min) between 0700-1900 hours on normal weekdays.
3.6.2
If
a school exists near the construction activity, noise monitoring shall be
carried out at the monitoring stations for the schools during the examination
periods. The ET Leader shall liaise with the school’s representatives and the
Examination Authority to ascertain the exact dates and times of all examination
periods during the course of the contract.
3.6.3
The
Action and Limit Levels for construction noise are given in Table 3.2 and the
Event/Action Plan in Table 3.3.
3.7
Event and Action Plan for
Construction Noise
3.7.1
In
case of non-compliance with the construction noise criteria, more frequent
monitoring as specified in the Action Plan in Table 3.3 shall be carried out.
This additional monitoring shall be continued until the recorded noise levels
are rectified or proved to be irrelevant to the construction activities. The ET
shall provide full documentation of his investigation on the cause of the
non-compliance and whether it can be traced to activities other than those
caused by the project, to the satisfaction of the ER and the IEC.
Action and Limit Levels for
Construction Noise
|
Time
Period |
Action |
Limit |
|
0700-1900
hrs on normal weekdays |
When
one documented complaint is received |
75* dB(A) |
* Reduced
to 70 dB(A) for schools and 65 dB(A) during school examination periods.
Table
3.3 Event/Action Plan for
Construction Noise Monitoring
EVENT
|
ACTION
|
|||
ET Leader
|
IEC |
ER |
Contractor |
|
|
Action Level |
1. Notify
IEC, Contractor and ER 2. Carry
out investigation and identify source 3. Report
the results of investigation to the IEC, Contractor and ER 4. Discuss
with the Contractor and formulate remedial measures 5. Increase
monitoring frequency 6. Check
compliance to Action/Limit Levels after application of mitigation measures |
1. Review
the analysed results submitted by the ET Leader 2. Review
the proposed remedial measures by the Contractor and advise the ER & ET accordingly 3. Review
the implementation of remedial measures |
1. Confirm
receipt of notification of complaint in writing 2. Notify
Contractor 3. Check
monitoring data submitted by the ET 4. Require
Contractor to propose remedial measures for the analysed noise problem 5. Ensure
remedial measures are properly implemented |
1.
Submit noise mitigation proposals to ER and IEC within three working 2. Liaise
with the ER to ensure the effectiveness of the agreed mitigation 3. Amend
proposal if required 4. Implement
noise mitigation proposals |
|
Limit Level |
1. Notify
IEC, ER, EPD and Contractor 2. Identify
Source 3. Repeat
measurement to confirm findings 4. Increase
monitoring frequency 5. Carry
out analysis of Contractor’s working procedures to determine possible
mitigation to be implemented 6. Inform
IEC, ER and EPD the causes & actions taken for the exceedances 7. Assess
effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER
informed of the results 8. If
exceedance stops, cease additional monitoring |
1. Check
monitoring data submitted by ET 2. Discuss
amongst ER, ET Leader and Contractor on the potential remedial actions 3. Review
Contractor’s remedial actions whenever necessary to assure their
effectiveness and advise the ER & ET accordingly 4. Audit
the implementation of remedial measures |
1. Confirm
receipt of notification of exceedance 2. Notify
Contractor 3. Check
monitoring data submitted by the ET 4. Require
Contractor to propose remedial measures for the analysed noise problem 5. Discuss
with ET, IEC and Contractor on proposed remedial actions to be implemented 6. Ensure
remedial measures are properly implemented 7. Assess
the effectiveness of the remedial actions and keep the Contractor informed 8. If
exceedance continues, consider what portion of the work is responsible and
instruct the Contractor to stop that portion of work until the exceedance is
abated |
1. Take
immediate action to avoid further exceedance 2. Submit
proposals for remedial actions to ER within 3 working days of notification 3. Liaise
with the ER to ensure the effectiveness of the agreed mitigation 4. Amend
proposal if required 5. Implement
the agreed proposals 6. Resubmit
proposals if problem still not under control 7. Stop
the relevant portion of works as determined by the ER until the exceedance is
abated |
3.8
Construction Noise Mitigation
Measures
3.8.1
Table 3.4 summarises the
mitigation measures proposed for the construction works. All these construction
noise mitigation measures should be implemented by the contractor during the
construction stage of the works. The location of the temporary noise barriers
should be further reviewed during the detailed design stage by the detailed
design engineer or by the Engineer during the construction stage based on the
latest construction programme and contemporary conditions, including any
changes with respect to NSRs. The contractor should design, construct, operate
and maintain the mitigation measures throughout the construction stage and as
required by the Engineer. Before commencement of the works, the contractor
should submit to the Engineer for approval (as part of their method statement)
details of the mitigation measures to be employed under the works. The contractor’s
proposed mitigation measures should also be certified by the ET Leader and
verified by the IEC to ensure the intended noise reduction effectiveness can be
achieved.
3.8.2
If
the above measures are not sufficient to restore the impacts to acceptable
levels upon the advice of ET Leader, the Contractor shall liaise with the ET
Leader on some other mitigation measures, endorsed by IEC and propose to ER for
approval, and implement the mitigation measures.
3.8.3
The
implementation schedule for the recommended mitigation measures is presented in
Appendix A.
Summary of Proposed Construction Noise Mitigation Measures
|
Proposed
Mitigation Measures |
Location |
Timing /
Duration |
Implementation
Agent |
Specific Requirements |
|
Use of quiet equipment including
QPME |
All construction works / sites |
During the construction period |
Contractor |
Some examples of quiet plant and
QPME are shown in Appendix B of the EIA. Contractor can propose other
suitable alternative equipment with similar or lower sound power level. |
|
Use of temporary noise barrier
(purpose-built site hoarding) and/or movable (mobile) noise barrier |
The temporary noise barrier shall be
located as per on Figures 4.4 to 4.6 (of the EIA), or wherever noisy
construction works are being carried out close (25m or less) to NSRs |
During the construction period |
Contractor |
Barriers should be of at least 2.5 m
high or able to shield construction equipment from NSR’s view. For
NSRs MUP04A-2 and MUP05-6, barrier should have a minimum height of 3.5 m and
3 m respectively. These barriers should be constructed of appropriate
material with a minimum superficial density of 7 kg/m2, with no
gaps or openings. Also, regular inspection and maintenance should be carried
out. Where barriers cannot block line of
sight, mobile barrier of 2.5 m high with a cantilevered upper portion should
be provided. |
|
Good site practices |
All construction works / sites |
During the construction period |
Contractor |
----- |
|
Public relation strategy |
All construction works / sites |
During the construction period |
Project office (Engineer) /
Contractor |
Maintain a 24-hour hotline for
enquiry and complaint, periodic communication with affected parties |
|
Restrict concurrent usage of several
construction equipment at the same time |
For construction works within 20m of
NSRs MUP04A-2 & MUP04B-2 and works at LMH01 |
During the construction period |
Contractor |
Contractor to propose details to the
Engineer and ET Leader for approval |
|
Employ quiet working method for
demolition of crossings Dump truck and concrete lorry mixer
parked outside the main village area One vehicular crossing or bank
improvement to be constructed at any one time to minimize cumulative impact |
For construction works at LMH01 |
During the construction period |
Contractor |
Contractor to propose details to the
Engineer and ET Leader for approval |