3.1.1
In
this section, the requirements,
methodology, equipment, monitoring locations, criteria and protocols for the
monitoring and audit of noise impacts during the construction phase of the
Project are presented. Noise levels
shall be monitored to evaluate the construction noise impact if there is any
planned noise sensitive receivers (NSRs) occupied within 300 m from the works
area of this Project during the proposed dredging works.
3.2.1
The
construction noise level shall be measured in terms of
the A-weighted equivalent continuous sound pressure level (Leq). Leq (30 minutes) shall be
used as the monitoring parameter for the time period between 0700 and 1900
hours on normal weekdays.
3.2.2
Supplementary
information for data auditing, statistical results such as L10 and L90 shall
also be obtained for reference. A
sample data record sheet based on the one presented in the EM&A Guidelines
for Development Projects in
3.3.1
In
accordance with the Technical Memorandum (TM) issued under the 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 shall be
accepted as valid only if the calibration levels before and after the noise
measurement agree to within 1.0 dB.
3.3.2
Noise
measurements shall not be made in fog, rain, wind with a steady speed exceeding
5 m/s or wind with gusts exceeding 10 m/s.
The wind speed shall be checked with a portable wind speed meter capable
of measuring the wind speed in m/s.
3.3.3
The
ET is responsible for the provision of the monitoring equipment. The ET 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
In
accordance with the findings of EIA study, it is anticipated that construction
activities, if unmitigated, would not cause any adverse noise impact to the
nearest NSRs in the vicinity of the work site. The predicted noise levels at the NSRs would
comply with construction noise criteria.
These nearest NSRs are designated for construction noise monitoring as
listed in Table 3.1 and illustrated in Figure 3.1.
The status and location of NSRs may change after issuing this
Manual. If such case exists, the ET
Leader shall propose updated monitoring locations and seek approval from EPD
and agreement from the ER and the IEC before baseline monitoring commences.
Table 3.1 Noise
Monitoring Stations during Construction Phase
|
Identification No. |
Noise Monitoring Location |
|
NM1 |
Planned Residential Development (R3 site) |
|
NM2 |
Planned Residential Development (R3 site) |
3.4.2
When
alternative monitoring locations are proposed, the monitoring locations shall
be chosen based on the following criteria:
·
Monitoring at noise sensitive
receivers close to the major site activities which are likely to have noise
impacts;
·
Monitoring at noise sensitive receivers as
defined in the Technical Memorandum; and
·
Assurance of minimal disturbance to the
occupants during monitoring.
3.4.3
The
monitoring station shall normally be at a point 1 m from the exterior of the noise
sensitive facade and be at a position 1.2 m above ground. If there is a problem with access to the
normal monitoring position, an alternative position shall be chosen, and a
correction to the measurements shall be made. For reference, a correction of +3 dB(A)
shall be made to the free field measurements. The ET shall agree with the IEC on the
monitoring position and the corrections adopted. Once the positions of 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 shall carry out baseline noise monitoring prior to the commencement of the
construction works. The baseline
monitoring shall be carried out daily for a period of at least two weeks. Before commencing the baseline
monitoring, the ET shall inform the IEC of the baseline monitoring programme
such that the IEC can conduct on-site audit to ensure accuracy of the baseline
monitoring results.
3.5.2
In
exceptional cases, when insufficient baseline monitoring data or questionable
results are obtained, the ET Leader shall liaise with the ER, EPD and IEC to
agree on an appropriate set of data to be used as a baseline reference and
submit to the ER for agreement and EPD for approval.
3.6
Impact Monitoring for Construction Noise
3.6.1
Noise
monitoring shall be carried out at the designated monitoring station. The monitoring frequency shall depend on
the scale of the construction activities.
The following is an initial guide on the regular monitoring frequency on
a weekly basis when noise generating activities are underway:
·
one set of measurement between 0700 and 1900 hours on
normal weekdays.
3.6.2
If
construction works are extended to include works during the hours of 1900 – 0700
as well as public holidays and Sundays, applicable permits under NCO shall be
obtained by the Contractor.
3.6.3
In
case of non-compliance with the construction noise criteria, more frequent
monitoring, as specified in the Event and 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.
3.7
Event and Action Plan for Construction Noise
3.7.1
The
Action and Limit Levels for construction noise are defined in Table 3.2. Should non-compliance of the criteria
occur, action in accordance with the Event and Action Plan in Table 3.3
shall be implemented.
Table 3.2 Action
and Limit Levels for Construction Noise
|
Time Period |
Action Level |
Limit Level |
|
0700 – 1900
hours on normal
weekdays |
When one
documented complaint is received |
75
dB(A) |
3.8.1
As
detailed in the EIA Report, construction activities would not cause noise exceedance
at the nearest NSRs. Only good site
practices are recommended to be properly implemented to further ameliorate the construction noise impacts. The good site practices recommended in
the EIA Report are summarised below:
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 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 the nearby NSRs.
l
Material
stockpiles and other structures should be effectively utilised, wherever
practicable, in screening noise from on-site construction activities.
3.8.2
The
implementation schedule for the recommended mitigation measures is presented in
Appendix C.
Table 3.3 Event and Action Plan for Construction Noise
|
EVENT |
ACTION |
|||
|
|
ET |
IC(E) |
ER |
CONTRACTOR |
|
Action
Level |
1. Notify
IEC and Contractor; 2. Carry
out investigation; 3. Report the
results of investigation to the IEC, ER and Contractor; 4. Discuss
with the Contractor and formulate remedial measures; 5. Increase
monitoring frequency to check mitigation effectiveness. |
1.
Review
the analysed results submitted by the ET; 2.
Review
the proposed remedial measures by the Contractor and advise the ER
accordingly; 3.
Supervise
the implementation of remedial measures. |
1.
Confirm
receipt of notification of failure in writing; 2.
Notify
Contractor; 3.
Require
Contractor to propose remedial measures for the analysed noise problem; 4.
Ensure
remedial measures are properly implemented. |
1. Submit
noise mitigation proposals to IEC; 2. Implement
noise mitigation proposals. |
|
Limit
Level |
1.
Identify source; 2.
Inform IEC, ER, EPD and Contractor; 3.
Repeat measurements 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 and 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.
Discuss amongst ER, ET, and Contractor on the
potential remedial actions; 2.
Review Contractor’s remedial actions whenever
necessary to assure their effectiveness and advise the ER accordingly; 3.
Supervise the implementation of remedial
measures. |
1.
Confirm
receipt of notification of failure in writing; 2.
Notify
Contractor; 3.
Require
Contractor to propose remedial measures for the analysed noise problem; 4.
Ensure
remedial measures properly implemented; 5.
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 IEC
within 3 working days of notification; 3. Implement
the agreed proposals; 4. Submit
further proposal if problem still not under control; 5. Stop
the relevant portion of works as instructed by the ER until the exceedance is
abated. |