3.1
In accordance with the EM&A Manual, impact noise levels should be
obtained at 2 noise monitoring stations. Impact noise monitoring was conducted
for at least once per week during the construction phase of the Project. The
Action and Limit level of the noise monitoring is provided in Appendix D.
3.2
Integrating Sound Level Meter was employed for noise monitoring. They were Type 1 sound level meters
capable of giving a continuous readout of the noise level readings including
equivalent continuous sound pressure level (Leq)
and percentile sound pressure level (Lx). They comply with International Electrotechnical Commission Publications 651:1979 (Type 1)
and 804:1985 (Type 1). Portable
electronic wind speed indicator capable of measuring wind speed in m/s was
employed to check the wind speed.
Table 3.1 details the noise monitoring equipment used.
Table 3.1 Noise
Monitoring Equipment
|
Equipment |
Model |
|
Integrating
Sound Level Meter |
Rion NL-31 |
|
Calibrator |
Rion NC73 |
3.3
Two monitoring stations were set up in accordance
with EM&A Manual. Table 3.2 describes details of the two monitoring
stations. The monitoring locations are shown in Figure 2.1.
Table
3.2 Locations
of Noise Monitoring Stations
|
Monitoring Station |
Identity / Description |
|
CN1 |
Block A, |
|
CN2 |
Block A, |
3.4
One set of 30-mins measurement at each monitoring station between 0700
and 1900 on normal weekdays at a frequency of once per week was required to
determine the impact noise level. Leq, L10
and L90 would be recorded.
Monitoring
Procedures
·
The Sound Level Meter was set on a tripod at a
height of
·
Façade measurements were made at all three
monitoring locations.
·
The battery condition was checked to ensure the
correct functioning of the meter.
·
Parameters such as frequency weighting, the time
weighting and the measurement time were set as follows:
-
frequency weighting: A
-
time weighting: Fast
-
time measurement: Leq(30
minutes) during non-restricted hours i.e. between 07:00 and 19:00 on normal
weekdays
·
Prior to and after each noise measurement, the
meter was calibrated using a Calibrator for 94 dB at 1000 Hz. If the difference in the calibration
level before and after measurement was more than 1 dB(A),
the measurement would be considered invalid and repeat of noise measurement
would be required after re-calibration or repair of the equipment.
·
The wind speed was frequently checked with a
portable wind meter.
·
During the monitoring period, the Leq ,
L10 and L90 were recorded. In addition, site conditions and noise
sources were recorded on a standard record sheet.
·
Noise measurement was paused during periods of high
intrusive noise (e.g. dog barking, helicopter noise) if possible. Observations
were recorded when intrusive noise was unavoidable.
·
Noise monitoring was cancelled in the presence of
fog, rain, wind with a steady speed exceeding
Maintenance
and Calibration
·
The microphone head of the sound level meter and
calibrator is cleaned with soft cloth at quarterly intervals.
·
The meter should be checked and calibrated at yearly intervals.
·
Calibration details for the sound level meter and calibrator are
provided in Appendix E.
3.5
The monitoring results for noise are summarized in
Table 3.3 and the monitoring data is provided in Appendix I.
Table
3.3 Summary
of Noise Monitoring Results in the Reporting Period
|
|
Average, dB(A), Leq (30 mins) |
Range, dB(A), Leq (30 mins) |
Limit Level, dB(A), Leq (30 mins) |
|
CN1 |
61.7 |
59.4 – 64.5 |
75.0 |
|
CN2 |
60.5 |
58.2 – 64.0 |
75.0 |
3.6
There was no noise complaint received in the reporting month, hence, no
action level exceedance was recorded. At both
monitoring locations, CN1 and CN2, all the monitoring results (daytime) were
below the limit level of 75 dB(A).
3.7
All the monitoring results lied within the range of the predicted noise
levels in the EIA report.
3.8
Major noise sources during the noise monitoring included the
construction activities from the Project and another project under the same
contract (concurrent project) carried out in the vicinity and nearby traffic
noise.