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:
¡P
Free
field measurements was made at monitoring location M-N3. A correction of +3 dB(A) shall be made to the free field measurements.
¡P
The
battery condition should be checked to ensure good functioning of the meter.
¡P
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
¡P
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.
¡P
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.
¡P
Noise
measurement should be paused during periods of high intrusive noise if possible
and observation shall be recorded when intrusive noise is not avoided.
¡P
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:
¡P
The
microphone head of the sound level meter and calibrator should be cleaned with
a soft cloth at quarterly intervals.
¡P
The
sound level meter and calibrator should be calibrated annually by a HOKLAS
laboratory or the manufacturer.
¡P
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 ¡V 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 period of Ho
Yu College was 27 October to 31 October 2020. Therefore, the limit level for
NMS3C was 65 dB (A) on 29 October 2020.
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 levels recorded at NMS3C on 12 and 29 October 2020 were 70.5 dB
(A) and 68.6 dB (A), which exceeded the limit level 70
dB (A) and 65 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 were 68.4
dB (A) and 64.7 dB (A) respectively, 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.