3               NOISE

Monitoring Requirements

3.1         Baseline noise monitoring was conducted for 14 days at the designated monitoring station, NM7, from 26 September 2011 to 12 October 2011(suspended on 28, 29 September 2011 and 3 October 2011 due to adverse weather condition). Logger function check and calibration was carried out according to manufacturer’s recommendations.  The equipment was checked and inspected not less than once every two days after the set up at monitoring station.

Monitoring Locations

3.2         Table 3.1 gives the location of the monitoring station, which is also shown in Figure 2.

Table 3.1        Location of Noise Monitoring Station

Monitoring Station

Location of Measurement

NM7

Open Area near Naval Base Barrack

Monitoring Equipment

3.3         Integrating Sound Level Meter was used for noise monitoring. The meter is a 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) and also complied with International Electrotechnical Commission Publications 651:1979 (Type 1) and 804:1985 (Type 1) specifications. Table 3.2 summarizes the noise monitoring equipment being used. Copies of the calibration certificates for the sound level meter and calibrator are attached in Appendix A.

Table 3.2        Noise Monitoring Equipment

Equipment

Model and Make

Quantity

Integrating Sound Level Meter

SVANTEK, Model no: SVAN 955

1

Calibrator

SVANTEK, Model no: SV 30A

1

Monitoring Parameters, Frequency and Duration

3.4         In accordance with the EM&A Manual, baseline noise for the A-weighted levels Leq, L10 and L90 was recorded.  Data obtained from the baseline noise monitoring was processed and presented according to the following periods:

Ÿ  Daytime: 0700-1900 hours on normal weekdays

Ÿ  Evening-time: 1900-2300 hours on normal weekdays

Ÿ  Holiday-time: 0700-2300 hours on general holidays including Sundays

Ÿ  Night-time: 2300-0700 hours of all days

 

3.5         The frequency and parameters of noise measurement are presented in Table 3.3.

Table 3.3        Frequency and Parameters of Noise Monitoring

Time Period

Duration, min

Parameter

Daytime on normal weekdays (0700-1900 hrs)

30

Leq, L10 & L90

 

Evening time on normal weekdays (1900-2300 hrs)

5

Holidays including Sundays (0700-2300 hrs)

All days during the night-time (2300-0700 hrs)

Monitoring Methodology and QA/QC Procedures

3.6         Weather data was recorded during the baseline period and is presented in Appendix D.  Air temperature and relative humidity data was obtained from the Hong Kong Observatory Webpage.  General weather conditions (i.e. sunny, cloudy or rainy), which are given in Appendix D, were recorded by field observation during equipment checking and estimated according to weather data from the Hong Kong Observatory.

 

Field Monitoring

 

3.7         The monitoring procedures are as follows:

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

·       For free field measurement, the meter was positioned away from any nearby reflective surfaces. All records for free field noise levels were adjusted with a correction of +3 dB(A).

·       The battery condition was checked to ensure good 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

- measurement time       : 5 minutes (Leq (30-min) would be determined for daytime noise by calculating the logarithmic average of six Leq (5min) data.)

·       Prior to and after noise measurement, the meter was 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 was considered invalid and repeat of noise measurement was required after re-calibration or repair of the equipment.

·       Noise monitoring was carried out continuously for 24 hours during the 14 days baseline monitoring period.  Monitoring data was recorded and stored automatically within the sound level meter system.  At the end of the monitoring period, noise levels in term of Leq, L90 and L10 were recorded.  In addition, site conditions and noise sources were recorded when the equipment were checked and inspected every two days.

 

·       All the monitoring data within the sound level meter system was downloaded through the computer software, and all these data was checked and reviewed within the computer.

 

Maintenance and Calibration

 

3.8         Maintenance and Calibration procedures were as follows:

·       The microphone head of the sound level meter and calibrator were cleaned with a soft cloth at quarterly intervals.

·       The sound level meter and calibrator were checked and calibrated at yearly intervals.

Results and Observations

 

Results

3.9         Baseline noise monitoring was conducted at the designated stations and alternative station in the period from 26 September 2011 to 12 October 2011(suspended on 28, 29 September 2011 and 3 October 2011 due to adverse weather condition). The monitoring schedule is shown in Appendix E.

3.10     The baseline noise monitoring results (Leq) are summarized in Table 3.4.  Supplementary information (L10 and L90) obtained during the baseline monitoring are provided in Table 3.5.  All baseline noise monitoring results are given in Appendices C1 to C3.  Graphical presentations of the data are provided in Appendix C4.  Weather conditions recorded during the baseline monitoring period are shown in Appendix D.

Table 3.4        Summary of Baseline Noise Levels

Period

(Measurement Duration)

Monitoring Station

Baseline Noise Levels (Leq)

Mean

Max

Min

Daytime 0700-1900 hrs on normal weekdays (30 min)

NM 7

65.9

68.7

60.7

Evening-time 1900-2300 hrs on normal weekdays (5 min) and Holidays 0700-2300 hrs

(5 min)

63.4

73.7

57.3

Night-time 2300-0700 hrs of the next day (5 min)

59.7

65.8

52.1

 

Table 3.5        Summary of Supplementary Information (L10 & L90) Obtained during Baseline Noise Monitoring

Period

(Measurement Duration)

 

Monitoring Station

Supplementary Information

L10

L90

Mean

Max

Min

Mean

Max

Min

Daytime 0700-1900 hrs on normal weekdays (5 min)

NM 7

68.1

71.6

62.8

61.5

64.7

51.2

Evening-time 1900-2300 hrs on normal weekdays (5 min) and Holidays 0700-2300 hrs

(5 min)

65.6

70.9

59.2

59.4

64.7

54.7

Night-time 2300-0700 hrs of the next day (5 min)

61.8

69.8

53.0

56.4

60.9

47.0

 

Observations

3.11     The weather was mainly cloudy or fine referring to the observations from the field staff during the baseline monitoring period. Nevertheless, rain, which might influence the noise measurement results, was recorded according to the information from Hong Kong Observatory.

3.12     During the baseline monitoring period, no construction activity was undertaken in the vicinity of the monitoring station.

3.13     The major noise source at the monitoring station was the traffic noise from the Container Port Road South closed to the site boundary of the Project.

Action and Limit Levels

3.14     The Action and Limit Levels were established in accordance with the EM&A Manual.  The baseline noise level shall be referenced during the compliance check in the impact noise monitoring period. Table 3.6 presents the Action and Limit Levels for construction noise.

Table 3.6        Action Limit Levels for Noise during Construction Period    

Time Period

Action Level

Limit Level

0700-1900 hrs on normal weekdays

When one documented complaint is received

75 dB(A)