1.
2.
3.
NOISE
3.1.1
In
accordance with the Contract Specific EM&A Manuals, Leq
(30min) monitoring is conducted for at least once a week during the
construction phase between 0700 and 1900 on normal weekdays at the designated monitoring
locations.
3.2
Monitoring Equipment
3.2.1
The
sound level meter used in noise monitoring shall comply with the International Electrotechnical Commission Publication (IEC) 651:1979
(Type 1) and 804:1985 (Type 1) specifications as referred to in the Technical
Memorandum issued under the Noise Control Ordinance (NCO).
3.2.2
Sound
level calibrator shall be used for the on-site calibration of the meter. This
calibrator complies with the IEC Publication 942 (1988) Class 1 and ANSI S1.40
- 1984. Noise measurements were only accepted to be valid if the calibration
levels from before and after the measurement agree to within 1.0 dB(A).
3.2.3
Measurements
shall be recorded to the nearest 0.1dB(A). Sound level
meters are programmed to measure A-weighted equivalent continuous sound
pressure level at 30-minute intervals between 0700 and 1900 on normal weekdays
at least once a week when construction activities are underway.
3.2.4
The model of the noise monitoring equipment used is summarized in Table 3.1.
3.3.1
The parameters and frequencies of impact noise monitoring is
summarized in Table 3.2.
3.4.1
Noise
measurement should be conducted as the following procedures:
·
Free field measurements was
made at monitoring location M-N3. A correction of +3 dB(A)
shall be made to the free field measurements.
·
The battery condition should be
checked to ensure good functioning of the meter.
·
Parameters such as frequency
weighting, the time weighting and the measurement time should set as follow:
(i) Frequency
weighting: A
(ii) Time
weighting: Fast
(iii) Measurement
time: continuous 5 minutes interval
·
Prior to and after noise
measurement, the meter shall be calibrated using the calibrator for 94.0 dB(A) at 1000 Hz. If the difference in the calibration level
before and after measurement is more than 1.0 dB(A),
the measurement will be considered invalid and repeat of noise measurement is
required after re-calibration or repair of the equipment.
·
The wind speed at the
monitoring station shall be checked with the portable wind meter. Noise
monitoring should be cancelled in the presence of fog, rain, and wind with a
steady speed exceeding 5 m/s, or wind with gusts exceeding 10 m/s.
·
Noise measurement should be
paused during periods of high intrusive noise if possible and observation shall
be recorded when intrusive noise is not avoided.
·
At the end of the monitoring
period, the Leq, L10 and L90
should be recorded. In addition, site conditions and noise sources should also
be recorded on a standard record sheet.
3.5
Maintenance and Calibration
3.5.1
Maintenance
and calibration procedures should also be carried out, including:
·
The microphone head of the
sound level meter and calibrator should be cleaned with a soft cloth at
quarterly intervals.
·
The sound level meter and
calibrator should be calibrated annually by a HOKLAS laboratory or the
manufacturer.
·
The calibration certificates
for noise monitoring equipment are provided in Appendix D.
3.6
Monitoring Locations
3.6.1
In
accordance with the Contract Specific EM&A Manual, two noise monitoring
locations, namely NMS2 and NMS3C are covered under Contract No. HY/2019/01
“Hong Kong-Zhuhai-Macao Bridge Hong Kong Boundary Crossing Facilities – Phase 2
and Other Works.
3.6.2
Due
to rejection from Ho Yu College (NMS3) for setting up
a noise monitoring station at their school, an alternative location at site
boundary of the site office area at Works Area WA2 (NMS3B) is proposed. Impact
noise monitoring has been relocated from NMS3B to Ying Tung Estate Market
Rooftop (NMS3C) on 20 August 2018 under Contract No. HY/2013/04. The same
baseline and Action and Limit levels for noise, as derived from the baseline
monitoring data recorded at Ho Yu College, are
adopted for this alternative noise monitoring location.
3.6.3
The
most updated locations are summarized in Table 3.3 and the locations of the noise
monitoring stations shown in Figure
3.
3.7.1
The
schedule of noise monitoring in reporting month is provided in Appendix E.
3.7.2
No
raining and wind with speed over 5 m/s was observed during noise monitoring according
to the onsite observation. The weather conditions during the monitoring month
are provided in Appendix K.
3.7.3
The
noise monitoring data are summarized in Table
3.4.
Detailed monitoring data are presented in Appendix F.
3.7.4
School
calendar of Ho Yu College was checked against noise
monitoring days at NMS3C. The examination periods of Ho
Yu College were 11 November 2021 to 16 November 2021. Therefore, the limit
level for NMS3C was 65 dB (A) on 15 November 2021.
3.7.5
No
Action / Limit Level exceedance of location NMS2 was recorded for construction
noise in the reporting month.
3.7.6
The
measured noise level recorded at NMS3C on 3 November 2021 were 71.1 dB (A), which
exceeded the limit level 70 dB (A). The noise level were higher than the
baseline level of 66.3 dB (A). Therefore, baseline correction was carried out
and the corrected noise levels which solely represent the noise level of
construction works was 69.4 dB (A), therefore there was no exceedance after
correction. As such the Event and Action Plan was not triggered.
3.7.7
During
the monitoring month, at NMS3C, road traffic along the Ying Tung Road and
non-project related construction activities at the nearby construction site was
observed.
3.7.8
The
Action and Limit Levels for noise impact monitoring have been set and are presented
in Appendix C.
3.7.9
The
Event and Action Plan for noise is given in Appendix H.