(1) Monitoring Location
Baseline noise monitoring was undertaken at three locations as shown in Figure 4.1.
(2) Monitoring Parameters and Frequency
The qualified staff undertook noise measurement at each location on three days including weekday and holiday. Noise monitoring was carried out using sound level meters with respect to Leq (30 min), Lmax, Lmin, L10 and L90. The measurement period was as in the following table.
|
Time Period |
Type |
Duration / min |
|
Daytime (07:00-19:00) |
A |
30 |
|
Evening time (19:00-23:00) |
B |
30 |
|
Night-time (23:00-07:00) |
C |
30 |
All noise measurements were conducted in accordance with the Technical Memorandum for Assessment on Noise from Places Other than Domestic Premises, Public Places or Construction Sites.
(3) Monitoring Equipment
As referred to the Technical Memorandum issued under the Noise Control Ordinance, sound level meters in compliance with the International Electromechanical Commission Publications 651:1979 (Type 1) and 804:1985 (Type 1) specification were used for carrying out the noise monitoring.
(4) Field Monitoring Methodology and QA/QC
Procedure
The sound level meter was set on a tripod at a height of 1.2m above ground level. The meter was positioned away from any nearby reflective surfaces. The battery condition was checked to ensure good functioning of the meter. Parameters such as frequency weighting, the time weighting and the measurement time would be set as follows:
- frequency weighting: A
- time weighting: Fast
- time measurement: 30 minutes
Prior to and after each noise measurement, the meter was calibrated using the 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 checked with the portable wind meter. No noise monitoring was conducted in the presence of fog, rain, and wind with a steady speed exceeding 5m/s, or wind with gusts exceeding 10m/s.
Noise measurement was paused during periods of high intrusive noise if possible and observation was recorded when intrusive noise could be avoided.
(5)
Monitoring Results
|
Date |
Time Period |
Monitoring Station |
Noise
Parameter, dB(A) |
|||||
|
Leq (30 min) |
L10 |
L90 |
Lmax |
Lmin |
Remarks |
|||
|
1/2/04 (Sunday) |
A |
LWT2 |
62.4 |
65.5 |
42.5 |
83.5 |
35.5 |
Traffic noise |
|
A |
LWT3 |
50.5 |
52.0 |
46.5 |
72.2 |
44.2 |
Pui O pumping station |
|
|
A |
ALWT2 |
56.5 |
60.0 |
44.0 |
75.8 |
36.5 |
Traffic noise |
|
|
B |
LWT2 |
55.0 |
59.5 |
40.0 |
68.7 |
39.3 |
Traffic noise |
|
|
B |
LWT3 |
49.8 |
50.0 |
46.5 |
78.8 |
44.5 |
Dog barking, Pui O pumping
station |
|
|
B |
ALWT2 |
52.5 |
55.5 |
41.0 |
73.2 |
37.1 |
Traffic noise Dog barking |
|
|
C |
LWT2 |
55.5 |
575 |
38.5 |
68.7 |
37.7 |
Traffic noise |
|
|
C |
LWT3 |
49.5 |
50.0 |
47.0 |
66.7 |
45.2 |
Pui O pumping station |
|
|
C |
ALWT2 |
50.9 |
53.5 |
41.5 |
67.9 |
36.6 |
Dog barking |
|
|
2/2/04 (Monday) |
A |
LWT2 |
67.4 |
72.1 |
60.0 |
77.4 |
55.0 |
Traffic noise |
|
A |
LWT3 |
52.3 |
55.3 |
47.7 |
69.4 |
45.6 |
Traffic noise, Dog
barking, Pui O pumping station |
|
|
A |
ALWT2 |
64.1 |
67.3 |
55.2 |
87.6 |
44.7 |
Traffic noise |
|
|
B |
LWT2 |
64.4 |
68.6 |
46.4 |
78.4 |
43.6 |
Traffic noise |
|
|
B |
LWT3 |
51.1 |
54.1 |
47.0 |
62.3 |
46.3 |
Traffic noise, Dog
barking, Pui O pumping station |
|
|
B |
ALWT2 |
61.5 |
65.2 |
48.2 |
76.1 |
42.4 |
Traffic noise |
|
|
C |
LWT2 |
61.2 |
65.1 |
47.1 |
77.2 |
41.8 |
Traffic noise, Dog barking |
|
|
C |
LWT3 |
48.7 |
50.8 |
45.7 |
58.7 |
43.7 |
Traffic noise, Pui O
pumping station |
|
|
C |
ALWT2 |
59.7 |
62.5 |
48.0 |
85.2 |
41.7 |
Traffic noise |
|