3.1.1
In accordance with the EM&A
Manual, Leq (30min) monitoring is conducted at least once a week when there are
Project-related construction activities being undertaken within a radius of 300
m from the monitoring stations. The monitoring is conducted during the
construction phase between 0700 and 1900 on normal weekdays at the designated
monitoring locations.
3.2.1
As referred to the requirements
of the Technical Memorandum (TM) issued under the NCO, the sound level meters
in compliance with the International Electro technical Commission Publications
651: 1979 (Type 1) and 804: 1985 (Type 1) specifications should be used for
carrying out the noise monitoring. Immediately prior to and following each
noise measurement, the accuracy of the sound level meter should be checked
using an acoustic calibrator generating a known sound pressure level at a known
frequency. The measurements may be accepted as valid only if the difference
between calibration levels obtained before and after the noise measurement is
less than 1.0 dB (94 dB ± 0.1 dB).
3.2.2
The details of the noise
monitoring equipment used are summarized in Table
7.
3.3.1
The parameters and frequencies
of impact noise monitoring is summarized in Table
8.
3.4.1
Noise measurement should be
conducted as the following procedures:
·
The monitoring station will set
at a point 1m from the exterior of the sensitive receivers building façade and
set at a position 1.2m above the ground. (In case façade measurement is not
feasible on-site, a free field correction of +3dB(A) will be applied.)
·
The battery condition was
checked to ensure good functioning of the meter.
·
Parameters such as frequency
weighting, the time weighting and the measurement time will set as follows:
§ frequency weighting: A
§ time weighting: Fast
§ measurement time: 30 minutes
·
Prior to and after noise
measurement, the meter shall be calibrated using the calibrator for 94.0 dB at
1000 Hz. If the difference in the calibration level before and after
measurement is more than 1.0 dB, the measurement will consider invalid and
repeat of noise measurement is required after re-calibration or repair of the
equipment.
·
Noise measurement should be
paused during periods of high intrusive noise if possible and observation shall
be recorded when intrusive noise is not avoided.
·
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. Calibration certificate of
the anemometer is provided in Appendix D.
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.
·
Relevant calibration
certificates are provided in Appendix D.
3.6.1
In accordance with the EM&A
Manual, three noise monitoring locations, namely CM1, CM2 and CM3 are covered
under Contract No. SPW 02/2023 “Environmental Team for Construction of Yuen
Long Effluent Polishing Plant Stage 1”.
3.6.2
The most updated locations are
summarized in Table 9 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 Action / Limit Level
exceedance of location CM1, CM2 and CM3 was recorded for construction noise in
the reporting month.
3.7.3
During the monitoring month, at
CM2, road traffic from the squatter house at the west of Yuen Long STW was
observed, at CM3, road traffic from the Nam Sang Wai Road was observed. No
effect that arose from the other special phenomena and work progress of the
concerned site for CM1 was noted during the current monitoring month.
3.7.4
No raining and wind with speed
over 5 m/s was observed during noise monitoring according to the onsite
observation. The weather and meteorological conditions during the monitoring
month are provided in Appendix K.
3.7.5
The Construction Noise
Monitoring Results are summarized in Table 10.
Detailed monitoring data are presented in Appendix
F.
3.7.6
The Action and Limit Levels for
Construction Noise have been set and are presented in Appendix C.
3.7.7
The Event and Action Plan for
Construction Noise is given in Appendix
H.
3.8.1 The noise monitoring data was compared with the EIA predictions as summarized in Table 11.
3.8.2
The construction noise
monitoring results at CM1, CM2 and CM3 were below the Maximum Predicted
mitigated Construction Noise Level in the approved Environmental Impact
Assessment (EIA) Report (Register No.: AEIAR-220/2019).