5.0       Noise Monitoring

 

5.1       Monitoring Requirements

 

Noise monitoring was conducted at 1 monitoring station as specified in the approved EM&A Monitoring Proposal for good site practice. The equipment, parameter, frequency, duration, methodology, calibration details, results and observations of the noise monitoring for the reporting month are presented in this section.

 

5.2        Monitoring Equipment

 

An Integrating Sound Level Meter was used for noise monitoring. It was a Type 1 sound level meter capable of giving a continuous readout of the noise level reading including equivalent continuous sound pressure level (Leq) and percentile sound pressure level (Lx). It complies with International Electro Technical Commission Publications 651:1979 (Type1) and 804:1985 (Type1), and speed in m/s was used to monitor the wind speed.

 

Table 5.1 summarizes noise monitoring equipment model being used. A copy of the calibration certificate for noise meter and calibrator are attached in Appendix C1.

 

Table 5.1           Noise Monitoring Equipment

Equipment

Model

Integrating Sound Level Meter

Rion NL-31 Sound Level Meter

Calibrator

Rion NC-73 Sound Level Calibrator

Portable Wind Speed Indicator

TSI Model 8340-M Air Velocity Meter

 

5.3        Monitoring Parameters, Duration and Frequency

 

Duration, frequencies and parameters of noise measurement are presented in Table 5.2.

 

Table 5.2           Duration, Frequencies and Parameters of Noise Monitoring

Time period

Duration/min

Parameters

Frequency

Day-time: 0700-1900 hrs

on normal weekday

30

Leq, L10, L90

Once per month

 

5.4       Monitoring Locations and Period

 

Noise monitoring was conducted at the noise monitoring location, N1 as shown in Figure 3.1 during the reporting month. Table 5.3 describes the location of the monitoring station.

 

Table 5.3           Noise Monitoring Locations

Monitoring station

Location

Type of Measurement

N1

Outside site Egress along Wan Po Road

Façade

 

The noise-monitoring period of monitoring station is summarized in Table 5.4.

 

            Table 5.4           Monitoring Period for noise monitoring stations

Noise monitoring stations

Monitoring Period

Day-time

N1

02/03/06

10:18

 

5.5        Monitoring Procedures and Calibration Details

 

Operation/Analysis Procedures

 

·         The Sound Level Meter was set on a tripod at a height of 1.2m above the ground.

·         For free field measurement, the meter was positioned away from any nearby reflective surfaces. 

·         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  :  5 mins

·         Prior to and after each noise measurement, the meter was calibrated using a Calibrator for 94 dB at 1000HZ.  If the difference in the calibration level before and after measurement was more than 1dB(A), the measurement would be considered invalid and repeat 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.

·         Free Field correction to the measurements should be made. Correction factor of +3dB(A) should be made to the free Field measurements.

·         Noise monitoring would be cancelled in the presence of fog, rain, wind with a steady speed exceeding 5m/s, or wind gusts exceeding 10m/s.

 

Maintenance and Calibration

 

·         The microphone head of the sound level meter and calibrator are cleaned with soft cloth in quarterly intervals.

·         The meter is sent to the supplier or HOKLAS laboratory to check and calibrated in yearly intervals.

 

5.6        Action and Limit Levels

 

The Action and Limit levels for noise levels derived as illustrated in Table 5.5.

 

Table 5.5                       Action and Limit Levels for noise monitoring

Time Period

Time Period

Action *

Limit *

Normal hours

0700-1900 hrs

on normal weekdays

When one documented complaint is received

75 dB(A)

*Traceable to Method Statement (Environmental Monitoring and Audit Manual) of Contract No.CV/2002/08, Rev. 2

 

5.7        Event-Action Plans

 

Please refer to the Appendix F for details. 

 

5.8               Results and Observation

 

5.8.1     Results

 

Only Day-time noise monitoring was carried out at monitoring station, N1 in this reporting month. Noise level is provided in Appendix C2. Graphical presentation of the monitoring result for the reporting month is shown in Appendix C3. A summary of the monitoring result is presented in Table 5.6.

 

Table 5.6           Summary of Impact Noise Level

Date

Start Sampling Time (hh:mm)

Noise Level dB (A)

Leq(30min)

L10

L90

02/03/06

10:18

71.7

75.8

59.8

 

No Day-time noise monitoring result at monitoring station N1 exceeded the Action Level since no documented complaints on noise issue were received in this reporting month. Besides, no exceedances in Limit Level were recorded according to the result from Day-time noise monitoring.

 

5.8.2          Observation

 

The major noise source during the monitoring event was the dump truck traffic. Operation of the Fill Bank was from 08:00 to 21:00 from Monday to Sunday in the reporting month. Whereas the operation hours for barge activities in the TKO Basin was from 08:00 to 23:00. The monitoring result complied with the noise limit of 75 dB(A).