3.
NOISE
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 3.1.
3.3
Monitoring Parameters and Frequency
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:
·
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 considered 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
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.
·
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 07/2020 “Environmental
Team for Construction of Yuen Long Effluent Polishing Plant Stage 1”.
3.6.2
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 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
3.4. 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
Comparison of Noise Monitoring data with EIA Predictions
3.8.1
The noise monitoring
data was compared with the EIA predictions as summarized in Table 3.5.
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).