3b.1.1.1
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. The proposed mitigation measures during
construction and operation phase of the Project are also described in this
section.
3b.1.1.2
Construction
noise impacts from this Project are predicted at the identified Noise Sensitive
Receivers (NSRs). Noise mitigation
measures would be required to reduce noise levels to the stipulated
standard. A noise monitoring programme
shall be undertaken to ensure such mitigation measures would be implemented
properly.
3b.2.1.1
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. For all other time periods,
Leq (5 minutes) shall be employed for comparison with the Noise Control
Ordinance (NCO) criteria.
3b.2.1.2
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
3b.2.1.3
As
referred in 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 may be accepted as valid only if
the calibration levels from before and after the noise measurement agree to
within 1.0 dB.
3b.2.1.4
Noise
measurements shall not be made in fog, rain, wind with a steady speed exceeding
3b.2.1.5
The
ET 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.
3b.2.1.6
The
locations of construction noise monitoring stations are summarized in Table 3b.1 and shown in Figure 3b.1. These locations represent the worst affected
sensitive receivers during construction phase of the Project.
Table 3b.1 Noise Monitoring Stations
Noise Monitoring Station |
NSR ID in EIA Report |
Noise Monitoring Location |
M1 |
N_S1 |
Shek Kwu Chau Treatment & Rehabilitation Centre Hostel 1 |
M2 |
N_S2 |
Shek Kwu Chau Treatment & Rehabilitation Centre Hostel 2 |
M3 |
N_S3 |
Shek Kwu Chau Treatment & Rehabilitation Centre Hostel 3 |
3b.2.1.7
The
status and locations of noise sensitive receivers 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.
3b.2.1.8
When
alternative monitoring locations are proposed, the monitoring locations shall
be chosen based on the following criteria:
(i)
Monitoring
at sensitive receivers close to the major site activities which are likely to
have noise impacts;
(ii)
Monitoring
at the noise sensitive receivers as defined in the Technical Memorandum; and
(iii)
Assurance
of minimal disturbance to the occupants during monitoring.
3b.2.1.9
The
monitoring station shall normally be at a point
3b.3.1.1
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 develop and submit to the IEC the baseline monitoring programme
such that the IEC can conduct on-site audit to ensure accuracy of the baseline
monitoring results.
3b.3.1.2
There
shall not be any construction activities in the vicinity of the stations during
the baseline monitoring.
3b.3.1.3
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 and IEC for agreement and EPD for approval.
3b.4.1.1
Noise
monitoring shall be carried out at all the designated monitoring stations. 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 weekly basis when noise generating activities are
underway:
· one set of measurements between 0700 and 1900 hours on normal weekdays.
3b.4.1.2
If
construction works are extended to include works during the hours of 1900 –
0700 as well as public holidays and Sundays, additional weekly impact
monitoring shall be carried out during respective restricted hours
periods. Applicable permits under NCO
shall be obtained by the Contractor.
3b.4.1.3
If
a school exists near the construction activity, noise monitoring shall be
carried out at the monitoring stations for the schools during the school
examination periods. The ET Leader shall
liaise with the school’s personnel and the Examination Authority to ascertain
the exact dates and times of all examination periods during the course of the
contract.
3b.4.1.4
In
case of non-compliance with the construction noise criteria, more frequent
monitoring as specified in the Action Plan shall be carried out. This additional monitoring shall be continued
until the recorded noise levels are rectified or demonstrated to be unrelated
to the construction activities.
3b.5.1.1
The
Action and Limit levels for construction noise are defined in Table 3b.2. Should
non-compliance of the criteria occur, action in accordance with the Event and
Action Plan in Table 3b.3 shall be implemented.
Table 3b.2 Action and Limit Levels for Construction Noise
Time Period |
Action Level |
Limit Level |
0700
– 1900 hours on normal weekdays |
When one documented compliant is
received |
75 dB(A) |
Notes: If works are to be carried out during
restricted hours, the conditions stipulated in the Construction Noise Permit
(CNP) issued by the Noise Control Authority have to be followed.
3b.6.1.1
To
alleviate the construction noise impact on the affected NSRs, movable noise
barriers and acoustic mats are proposed to be provided for particular items of
plant and construction works. It is
anticipated that a movable noise barrier with a cantilevered upper portion
located within
3b.6.1.2
In
addition, the good site practices listed below shall be adopted by all the
Contractors to further ameliorate the noise impacts.
· Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program.
· Silencers or mufflers on construction equipment should be utilised and should be properly maintained during the construction program.
· Mobile plant, if any, should be sited as far away from NSRs as possible.
· 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.
· 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.
· Material stockpiles and other structures should be effectively utilised, wherever practicable, in screening noise from on-site construction activities.
3b.6.1.3
If
the above measures are not sufficient to restore the construction noise quality
to acceptable levels upon the advice of ET Leader, the contractor shall liaise
with the ET Leader to identify further mitigation measures. They shall be proposed to ER for approval,
and the contractor shall then implement these additional mitigation measures.
The
Contractor should carry out a noise commissioning test for all fixed noise
sources before operation of the Project, in order to ensure compliance of the
operational airborne noise levels with the TM’s stipulated noise standard.
Table 3b.3 Event/Action Plan for Construction Noise
EVENT |
ACTION |
|||
ET |
IEC |
ER |
CONTRACTOR |
|
Action Level being exceeded |
1.
Notify ER, IEC and Contractor; 2.
Carry out investigation; 3.
Report the results of investigation to the IEC, ER
and Contractor; 4.
Discuss with the IEC and Contractor on remedial
measures required; 5.
Increase monitoring frequency to check mitigation
effectiveness. (The above actions
should be taken within 2 working days after the exceedance is identified) |
1.
Review the investigation results submitted by the
ET; 2.
Review the proposed remedial measures by the
Contractor and advise the ER accordingly; 3.
Advise the ER on the effectiveness of the proposed
remedial measures. (The above actions should be
taken within 2 working days after the exceedance is identified) |
1. Confirm receipt of
notification of failure in writing; 2. Notify Contractor; 3. In consolidation
with the IEC, agree with the Contractor on the remedial measures to be
implemented; 4. Supervise the
implementation of remedial measures. (The above actions should be taken
within 2 working days after the exceedance is identified) |
1. Submit noise mitigation proposals to IEC
and ER; 2. Implement noise mitigation proposals. (The above actions should be taken
within 2 working days after the exceedance is identified) |
Limit Level being exceeded |
1. Inform IEC, ER,
Contractor and EPD; 2. Repeat
measurements to confirm findings; 3. Increase
monitoring frequency; 4. Identify source
and investigate the cause of exceedance; 5. Carry out analysis
of Contractor’s working procedures; 6. Discuss with the
IEC, Contractor and ER on remedial measures required; 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. (The above actions should be
taken within 2 working days after the exceedance is identified) |
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. (The above actions should be
taken within 2 working days after the exceedance is identified) |
1. Confirm receipt of
notification of failure in writing; 2. Notify Contractor; 3. In consolidation
with the IEC, agree with the Contractor on the remedial measures to be
implemented; 4. Supervise the
implementation of remedial measures; 5. If exceedance
continues, consider stopping the Contractor to continue working on that
portion of work which causes the exceedance until the exceedance is abated. (The above actions should be
taken within 2 working days after the exceedance is identified) |
1.
Take immediate action to avoid further exceedance; 2.
Submit proposals for remedial actions to IEC and ER
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. (The above actions should be
taken within 2 working days after the exceedance is identified) |