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
Monitoring Parameters and Frequency
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
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 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
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 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).
4.