4.              NOISE

Monitoring Requirements

 

4.1              According to EM&A Manual of the Project, construction noise monitoring was conducted 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 A shows the established Action and Limit Levels for the environmental monitoring works.

Monitoring Locations

4.2              Noise monitoring was conducted at 8 designated monitoring stations (CM1, CM2, CM3, CM4, CM5, CM6(A), CM7(A), CM8(A)) in the reporting period. Table 4.1 and Figure 3 show the locations of these stations.

 

Table 4.1        Noise Monitoring Stations

Monitoring Stations

Locations

Location of Measurement

CM1

Nga Lai House, Yau Lai Estate Phase 1, Yau Tong

Rooftop (41/F)/Refuge floor (26/F)# 

CM2

Bik Lai House, Yau Lai Estate Phase 1, Yau Tong

Rooftop (41/F)

CM3

Block S, Yau Lai Estate Phase 5, Yau Tong

Rooftop (40/F)

CM4

Tin Hau Temple, Cha Kwo Ling

Ground Level

CM5

CCC Kei Faat Primary School, Yau Tong

Rooftop (6/F)

CM6(A)*

Site Boundary of Contract No. NE/2015/02 near Tower 1, Ocean Shores

Ground Level

CM7(A)*

Site Boundary of Contract No. NE/2015/02 near Tower 7, Ocean Shores

Ground Level

CM8(A)*

Park Central, L1/F Open Space Area

1/F

Remarks: *       Noise monitoring at designated station CM6, CM7 & CM8 was rejected by the premise owners. Therefore, baseline and impact noise monitoring works were carried out at alternative noise monitoring stations CM6(A), CM7(A) and CM8(A) respectively.

                # Monitoring location has changed from 41/f to 26/f on 23rd Nov 2018.

Monitoring Equipment

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 B.

 

Table 4.2        Noise Monitoring Equipment

Equipment

Model and Make

Quantity

Integrating Sound Level Meter

SVAN 955/ 957 / 977

5

BSWA 801

5

Calibrator

SV30A

2

Brüel & Kjær 4231

2

 

 

4.4              Table 4.3 summarizes the monitoring parameters, frequency and total duration of monitoring.  The noise monitoring schedule is shown in Appendix D. Additional weekly impact monitoring are carried out for evening time (1900 – 2300 hours) , night-time (2300 – 0700 hours) and daytime (0700- 1900 hours) during general holidays including Sundays for monitoring stations CM1, CM2, CM3 and CM4.

 

Table 4.3        Frequency and Parameters of Noise Monitoring

Monitoring Stations

Parameter

Period

Frequency

Measurement

CM1

L10(30 min) dB(A)

L90(30 min) dB(A)

Leq(30 min) dB(A)

0700-1900 hrs on normal weekdays

 

Once per     week

Façade

CM2

Façade

CM3

Façade

CM4

Façade

CM5

Façade

CM6(A)

Free Field

CM7(A)

Free Field

CM8(A)

Façade

CM1

L10(5 min) dB(A)

L90(5 min) dB(A)

Leq(5 min) dB(A)

1900 – 2300 hrs on normal weekdays/ 0700 to 1900 hours on
any day being a
Sunday or general
holiday /
2300-0700 on all day

 

Façade

CM2

 

Façade

CM3

 

Façade

CM4

 

Façade

Monitoring Methodology and QA/QC Procedure

4.5              The monitoring procedures are as follows:

·              The monitoring station was normally be at a point 1m from the exterior of the sensitive receivers building façade and be at a position 1.2m above the ground. 

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

·              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 was set as follows:

- frequency weighting     : A

- time weighting              : Fast

- measurement time         : 30 minutes

·              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 will be 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.

·              At the end of the monitoring period, the Leq, L90 and L10 was recorded.  In addition, noise sources was recorded on a standard record sheet.

·              Noise monitoring will be 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. Supplementary monitoring was provided to ensure sufficient data would be obtained.

 

Maintenance and Calibration

 

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

 

4.7              The sound level meter and calibrator was checked and calibrated at yearly intervals.

 

4.8              Immediately prior to and following each noise measurement the accuracy of the sound level meter was checked using an acoustic calibrator generating a known sound pressure level at a known frequency. Measurements may be accepted as valid only if the calibration levels from before and after the noise measurement agree to within 1.0 dB.

Results and Observations

4.9              Nine (9) Action Level exceedance was recorded due to the documented complaints received in this reporting month. Twelve (12) Limit Level exceedance for night-time construction noise monitoring and they were considered due to the road Traffic near Eastern Cross Harbour Tunnel Toll Plaza, therefore non-Project related. One (1) Limit Level exceedance for day time was recorded in the reporting month and it was considered Project related.

 

4.10          Noise monitoring results and graphical presentations are shown in Appendix G.

 

4.11          The major noise source identified at the noise monitoring stations are shown in Table 4.4.

 

Table 4.4        Major Noise Source during Noise Monitoring

Monitoring Stations

Locations

Major Noise Source

CM1

Nga Lai House, Yau Lai Estate Phase 1, Yau Tong

Road Traffic near Eastern Cross Harbour Tunnel Toll Plaza

CM2

Bik Lai House, Yau Lai Estate Phase 1, Yau Tong

Road Traffic near Eastern Cross Harbour Tunnel Toll Plaza

CM3

Block S, Yau Lai Estate Phase 5, Yau Tong

Road Traffic near Eastern Cross Harbour Tunnel Toll Plaza

CM4

Tin Hau Temple, Cha Kwo Ling

Road Traffic at Cha Kwo Ling Road

CM5

CCC Kei Faat Primary School, Yau Tong

Road Traffic at Yau Tong Road

CM6(A)

Site Boundary of Contract No. NE/2015/02 near Tower 1, Ocean Shores

Road Traffic at O King Road near Ocean Shores

CM7(A)

Site Boundary of Contract No. NE/2015/02 near Tower 7, Ocean Shores

Road Traffic at Tong Yin Street

CM8(A)

Park Central, L1/F Open Space Area

Road Traffic at Po Yap Road

 


4.12          All the Construction Noise Levels (CNLs) reported in this report were adjusted with the corresponding baseline level (i.e. Measured Leq – Baseline Leq = CNL), in order to facilitate the interpretation of the noise exceedance. The baseline noise level and the Noise Limit Level at each designated noise monitoring station are presented in Table 4.5, 4.6 and 4.7.

 

Table 4.5                    Baseline Noise Level and Noise Limit Level for Monitoring Stations

Station

Baseline Noise Level, dB (A)

(at 0700 – 1900 hrs on normal weekdays)

Noise Limit Level, dB (A)

 (at 0700 – 1900 hrs on normal weekdays)

CM1

65.5

75

CM2

63.6

CM3

65.6

CM4

62.0

CM5

68.2

70*

CM6(A)

61.9

75

CM7(A)

58.3

CM8(A)

69.1

(*)        Noise Limit Level is 65 dB(A) during school examination periods.

 

Table 4.6                    Baseline Noise Level and Noise Limit Level for Monitoring Stations (Evening-time & Daytime (Holiday))

Station

Baseline Noise Level, dB (A)

(Evening time on all days (1900-2300 hrs) and Holidays (including Sundays) during daytime (0700-1900 hrs))

Noise Limit Level, dB (A)

(Evening time on all days (1900-2300 hrs) and Holidays (including Sundays) during daytime (0700-1900 hrs))

CM1

64.4

70

CM2

62.2

CM3

64.7

CM4

57.0

 

Table 4.7                    Baseline Noise Level and Noise Limit Level for Monitoring Stations (Night-time)

Station

Baseline Noise Level, dB (A)

(Night-time (2300 – 0700 hrs)

Noise Limit Level, dB (A)

(Night-time (2300 – 0700 hrs)

CM1

60.5

55

CM2

58.0

CM3

60.2

CM4

55.8

 

 

Current Tunnel Blasting Arrangement 

 

4.13          The drill and blast method was evaluated as the most appropriate method and the general practice of this method was introduced during the EIA report assessment. The paragraphs 2.9.9 and 2.9.33 of the EIA Report mention that there might be one blast or multiple blasts and the maximum number of blast location per day would be   determined by the Contractor to suite his method of working.

 

4.14          Notwithstanding the information provided by the Engineer at paragraphs 4.6.4 and 6.6.12 of the EIA Report, to minimize blast nuisance to the public and to respond to the community concerns, the tunnel blast should be arranged, where possible, avoiding the blast to be carried out during night time and shortening the blast duration by arranging various work fronts to be blasted at different time slots. Hence, it has become more desirable to split one tunnel blasting operation, which may consist of several blasting work fronts along the tunnels, into a total of two to three tunnel blasts per day. The tunnel blasts, which locate outside the MTR Protection Zone (RPZ) possessing insignificant risk to the MTR's structures would be carried out during day time and before 22:00. For the tunnel blasts within and in close vicinity to RPZ, Contractor's blasting assessment report revealed that those blasts have to be carried out after train service and, generally, at around 01:40.