4.1
In accordance with Updated EM&A Manual, construction
noise monitoring was conducted in terms of the A-weighted equivalent continuous
sound pressure level (Leq) to monitor the
construction noise arising from the construction activities. The regular
monitoring frequency for each monitoring station shall be on a weekly basis and
conduct one set of measurements between 0700 and 1900 hours on normal weekdays.
Appendix B shows the established
Action and Limit Levels for the environmental monitoring works.
4.2
Impact noise monitoring was conducted at the
monitoring stations, as shown in Figure 3
and 4 according to Table 1.1 of
Updated EM&A Manual. Table 4.1 describes the locations of
the noise monitoring stations.
Table 4.1 Location
of Noise Monitoring Stations
|
Contract No. |
Monitoring Station(s) |
Location(s) |
|
ND/2019/01 ND/2019/03 |
CP-KTN-NMS2 |
Residential Buildings at Ma Tso Lung |
|
CP-KTN-NMS3 |
Fung Kong Garden |
|
|
ND/2019/01 |
CP-KTN-NMS5 |
N/A |
|
ND/2019/05 |
CP-FLN-NMS2 |
Scattered Village Houses in Tong Hang |
|
ND/2019/06 |
CP-FLN-NMS1 |
Belair Monte |
Remark:
Noting that construction phase
noise monitoring at the other proposed monitoring stations (e.g. planned),
where access is permitted, will be conducted during the relevant works
contract(s).
4.3
Integrating Sound Level Meter was used for impact
noise monitoring. The meters are Type 1 sound level meter capable of giving a
continuous readout of the noise level readings including equivalent continuous
sound pressure level (Leq) and percentile sound
pressure level (Lx) that also complied with International Electrotechnical
Commission Publications 651:1979 (Type 1) and 804:1985 (Type 1) specifications.
Table 4.2 summarizes the noise
monitoring equipment being used. Copies of calibration certificates are
attached in Appendix C.
Table
4.2 Noise
Monitoring Equipment
|
Equipment |
Manufacturer |
Model |
Quantity |
|
‘SVANTEK’ Integrating Sound Level Meter |
SVANTEK |
SVAN 977 |
1 |
|
Sound & Vibration Analyser |
BSWA |
BSWA 801 |
1 |
|
Acoustical
Calibrator |
Brüel & Kjær |
4231 |
2 |
|
SVANTEK |
SV30A |
1 |
4.4
Table
4.3 summarises the monitoring parameters, frequency and total
duration of monitoring. The noise
monitoring schedule is shown in Appendix
D.
Table 4.3 Noise
Monitoring Parameters, Duration and Frequency
|
Contract No. |
Monitoring Stations |
Parameter |
Duration |
Frequency |
Measurement |
|
ND/2019/01 ND/2019/03 |
CP-KTN NMS2 |
L10(30 min.) dB(A) L90(30 min.) dB(A) Leq(30 min.)dB(A) (as six consecutive Leq, 5min
readings) |
0700-1900 hrs on normal weekdays |
Once
per week |
Free-field[1] |
|
CP-KTN NMS3 |
|||||
|
ND/2019/01 |
CP-KTN NMS5 |
||||
|
ND/2019/06 |
CP-FLN-NMS1 |
Façade |
|||
|
ND/2019/05 |
CP-FLN-NMS2 |
Remarks:
[1]: Correction of +3dB (A)
for Free-field Measurement.
[2]:
A-weighted equivalent continuous sound pressure level (Leq).
It is the constant noise level which, under a given situation and time period,
contains the same acoustic energy as the actual time-varying noise level.
L10 is
the level exceeded for 10% of the time. For 10% of the time, the sound or noise
has a sound pressure level above L10.
L90 is
the level exceeded for 90% of the time. For 90% of the time, the noise level is
above this level.
·
The microphone head of the sound level meter
was positioned at 1m from the exterior of the noise sensitive facade and
lowered sufficiently so that the building’s external wall acted as a reflecting surface;
·
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 min.) dB(A)
(as six consecutive Leq, 5min readings)
during non-restricted hours (i.e. 0700-1900 hrs on
normal weekdays)
·
Prior to and
after each noise measurement, the meter was calibrated using a Calibrator for
94.0 dB at 1000 Hz. If the
difference in the calibration level before and after measurement was more than
1.0 dB, the measurement would be considered invalid and repeat of noise
measurement would be required after re- calibration or repair of the equipment;
·
During the monitoring period, the Leq, L90 and L10 were recorded. In
addition, site conditions and
noise sources were recorded on a standard record sheet;
·
Noise
measurement was paused temporarily during periods of high intrusive noise (e.g.
dog barking, helicopter noise) if possible and observation record during
measurement period should be provided; and
·
Noise
monitoring was 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. The wind speed should
be checked with a portable wind speed meter capable of measuring the wind speed
in m/s.
4.5
The microphone head of the sound level meter
and calibrator were cleaned with a soft cloth at quarterly intervals.
4.6
The sound level meter and calibrator were
checked and calibrated at yearly intervals.
4.7
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. Measurements would be accepted as valid only if the calibration
levels before and after the noise measurement agreed to within 1.0 dB.
4.8
The noise monitoring results are summarised in Table 4.4.
Detailed monitoring results and graphical presentations of noise monitoring are
shown in Appendix F. The weather
information for the reporting month is summarized in Appendix I.
Table 4.4 Summary
Table of Noise Monitoring Results during the Reporting Month
|
Contract No. |
Monitoring Station |
Noise Level Leq (30 min), dB(A) |
Baseline
Level, dB(A) |
Limit Level,
dB(A) |
|
ND/2019/01 ND/2019/03 |
CP-KTN-NMS2 |
52.9-56.8 |
58.6 |
75 |
|
CP-KTN-NMS3 |
54.7-59.2 |
51.6 |
||
|
ND/2019/01 |
CP-KTN-NMS5 |
53.5-62.2 |
57.2 |
|
|
ND/2019/06 |
CP-FLN-NMS1 |
67.6-69.2 |
69.9 |
|
|
ND/2019/05 |
CP-FLN-NMS2 |
57.1-69.2 |
59.6 |
4.9
All noise monitoring was conducted as
scheduled in the reporting month. No complaint was received during the reporting.
No Action/Limit Level exceedance was recorded. The summary of exceedance
record in reporting month is shown in Appendix
K.
4.10
According to our field observations, the
major noise source identified at the designated noise monitoring stations in
the reporting month are as follows:
Table 4.5 Observation
at Noise Monitoring Stations
|
Contract No. |
Monitoring Station |
Location |
Major Noise Source |
|
ND/2019/01 ND/2019/03 |
CP-KTN-NMS2 |
Residential
Buildings at Ma Tso Lung (Existing) |
Road Traffic near Ma Tso Lung |
|
CP-KTN-NMS3 |
Fung Kong Garden
(Existing) |
Road Traffic near Fung Kong Garden |
|
|
ND/2019/01 |
CP-KTN-NMS5 |
N/A |
Other construction site |
|
ND/2019/06 |
CP-FLN-NMS1 |
Belair Monte (Existing) |
Road Traffic at Ma Sik Road |
|
ND/2019/05 |
CP-FLN-NMS2 |
Scattered Village
House in Tong Hang (Existing) |
Road Traffic near Tong Hang |
4.11
Should any project related non-compliance of
the criteria occur, action in accordance with the Action Plan in Appendix J shall be carried out.