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. For all other time periods, Leq(5 min) shall be employed for comparison with the Noise Control Ordinance (NCO) criteria.
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.
As
referred to in the Technical Memorandum (TM) issued under NCO, sound level
meters in compliance with the International Electromechanical 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. The calibration record shall be provided and documented in the
EM&A reports.
Noise measurements should not be made in the presence of fog, rain, and
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.
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.
Tuen Mun Wu Hong Clinic was not identified as one of the noise
monitoring stations because the clinic does not rely on openable window for
ventilation. Table 3.1 shows the proposed noise monitoring station.
Table 3.1 Proposed Noise Monitoring Stations
|
Identification No. |
Description of NSR |
|
NSR1 |
Block 15, Yuet Wu Villa |
Location of the station is shown in Figure 2.1. If for whatever reasons it is necessary to establish alternative monitoring stations, the ET shall propose the alternative monitoring locations and seek approval from ER and agreement from IEC and EPD on the proposal. 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 most affected existing noise sensitive receivers
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.
The monitoring station shall normally be at a point 1 m from the exterior of the sensitive receivers building facade and be at a position 1.2 m 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. The ET Leader shall agree with the 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.
The ET Leader 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. A schedule on the baseline monitoring shall be submitted to
the ER for approval before the monitoring starts.
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 the IEC and
EPD to agree on an appropriate set of data to be used as a baseline reference
and submit to the ER for approval.
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 for the station on a per week basis when noise generating activities are underway:
a) One set of measurement between 0700-1900 hours on normal weekdays;
General construction work carryiedng out during restricted hours is
controlled by CNP system under the NCO.
In case of non-compliance with the construction noise criteria, more frequent monitoring as specified in the Action Plan in Table 3.2 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.
A schedule on the compliance monitoring shall be submitted to the ER
for approval before the monitoring starts.
3.6 Event and
Action Plan for Noise
The Action and Limit levels
for construction noise are defined in Table 3.2. Should an non-compliance of the criteria occurs,
action in accordance with the Action Plan in Table 3.3 shall be carried out.
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) |
|
0700-2300 hours on holidays; and 1900-2300 hours on all other days |
60/65/70**
dB(A) |
|
|
2300-0700 hours of next day |
45/50/55**
dB(A) |
* reduce
to 70 dB(A) for schools and 65 dB(A) during school examination periods
** to
be selected based on Area Sensitivity Rating
Note : If works are to be carried out during restricted hours, the conditions stipulated in the construction noise permit issued by the Noise Control Authority have to be followed.
Table 3.3 Event/Action Plan for Construction Noise
|
EVENT |
ACTION |
|||
|
ET |
IEC |
ER |
Contractor |
|
|
Action Level |
1. Notify IEC and
Contractor 2. Carry out
investigation 3. Report the
results of investigation to the IEC and Contractor 4. Discuss with
the Contractor and formulate remedial measures 5. Increase
monitoring frequency to check mitigation effectiveness |
1.
Review the analys 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 analys 4. Ensure remedial
measures are properly implemented |
1. Submit
noise mitigation proposals to IEC 2. Implement
noise mitigation proposals |
|
Limit Level |
1. Notify IEC, 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 ER and
EPD the causes & actions taken for the exceedances 7. Assess
effectiveness of Contractor’s remedial actions and keep 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 analys 4.
Ensure remedial measures are 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 ER within 3 working days of notification 3. Implement
the agreed proposals 4. Resubmit
proposals if problem still not under control 5. Stop the
relevant portion of works as determined by the ER until the exceedance is
abated |
The EIA report has
discussed in general terms the appropriate noise control and
mitigation measures
during the construction and operational phases, these are provided in more
detail below. The Contractor shall implement noise mitigation measures thatwhich shall
include, but not be limited to, the following:
· Scheduling of work – The Contractor shall make the choice of the number and types of construction equipment taking into account the use of a quiet plant while devising a feasible work programme.
· The Contractor shall take all necessary measures to ensure that the operation of all mechanical equipment and construction processes on or off the Site shall not cause any unnecessary and excessive noise which may disturb any occupant of any nearby dwellings, schools, hospitals, or premises with similar sensitivity to noise. The Contractor shall submit to the ER for his approval details of all Constructional Plant including methods of use and construction operations together with proposed measures for limiting noise level.
· The Contractor shall be responsible for obtaining Construction Noise Permits (CNPs) from the EPD as required for his operations. The locations of suspected Noise Sensitive Receivers (NSRs) are indicated in the Particular Specification, but the Contractor shall be responsible for obtaining and complying with the requirements for the EPD regarding identification of the NSRs and conditions attached to the CNPs. All correspondence with the EPD and each issued CNP shall be copied to the ER.
·
Oonly well-maintained plant shall be
operated on-site and the plant shall be serviced regularly during the
construction programme;
·
Mmachines and plant that may be in
intermittent use shall be shut down between work periods or shall be throttled
down to a minimum;
·
Pplants known to emit noise strongly in
one direction, shall, where possible, be orientated so that the noise is directed away from
nearby NSRs;
·
Ssilencers or mufflers on construction
equipment shall be utilised and shall be properly maintained during the
construction period;
·
Mmobile plants shall be sited as far
away from NSRs as possible; and
·
Mmaterial stockpiles and other
structures shall be effectively utilised, where practicable, to screen noise
from on-site construction activities.
If the above measures inare not sufficient
to restore the noise to acceptable levels upon the advice of ET Leader, the
Contractor shall liaise with the ET Leader on some other mitigation measures,
propose to ER for approval, and implement the mitigation measures.