PWP Item No. 4331DS

Outlying Islands Sewerage Stage 2 – South Lantau Sewerage Works

Environmental Impact Assessment Report

178711/B&V/0029/Draft H

July 2014 23 B&V / ERM

ANNEX 8A

Methodology for Baseline Noise Measurements

ENVIRONMENTAL RESOURCES MANAGEMENT

8A-1

8A1 BASELINE NOISE MEASUREMENTS

8A1.1 OBJECTIVE OF THE BASELINE NOISE MONITORING

The objective of the baseline noise monitoring is to provide up-to-date

baseline conditions of the noise environment of the Study Area for assessment

of potential environmental impacts caused by the Project activities and

recommendation of mitigation measures to mitigate such impacts.

8A1.2 STUDY AREA FOR NOISE ASSESSMENT

The Study Area for noise assessment is defined by a distance of 300 m from

the Project Boundary (Figure 1).

8A1.3 SCOPE OF WORKS & METHODOLOGY

To investigate the prevailing noise levels within the Study Area, continuous

24-hour noise measurements were made at selected monitoring stations. The

noise measurements were conducted with reference to the instrumentation,

calibration and measurement procedures as stated in the Technical

Memorandum for the Assessment of Noise from Places other than Domestic Premises,

Public Places or Construction Sites (IND-TM).

In case continuous 24-hour noise measurement is considered not practicable

due to inaccessibility of the designated monitoring locations, measurements

were carried out alternatively for a period of not less than two hours for each

of the daytime (ie, 0700 to 1900 hours), evening (ie, 1900 to 2300 hours) and

nighttime (ie, 2300 to 0700 hours) period.

8A1.3.1 Monitoring Parameters

The baseline noise level was measured in terms of the A-weighted equivalent

continuous sound pressure level (Leq). Leq (30 minutes) was used as the

monitoring parameter for the time period between 0700 and 1900 hours on

normal weekdays. For all other time periods, Leq (5 minutes) was employed as

the monitoring parameter for comparison with the Noise Control Ordinance

(NCO) criteria.

Supplementary information for data auditing and statistical results such as L10

and L90 were also obtained for reference.

8A1.3.2 Monitoring Equipment and Methodology

As referred to the requirements of the Technical Memorandum (TM) issued

under the NCO, sound level meters in compliance with the International

Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985

(Type 1) specifications were used for carrying out the noise monitoring.

Immediately prior to and following each noise measurement the accuracy of

ENVIRONMENTAL RESOURCES MANAGEMENT

8A-2

the sound level meter was checked using an acoustic calibrator generating a

known sound pressure level at a known frequency. Measurements were

accepted as valid only if the difference between calibration levels obtained

before and after the noise measurement is less than 1.0 dB.

Noise measurements were made in accordance with standard acoustical

principles and practices in relation to weather conditions. Noise

measurements were not made in the presence of fog, rain, wind with a steady

speed exceeding 5 ms-1 or wind with gusts exceeding 10 ms-1. The wind speed

were checked with a portable wind speed meter capable of measuring wind

speeds in m/s.

8A1.3.3 Monitoring Locations

The preliminary designated locations for baseline noise monitoring are listed

in Table 1.1 and shown in Figure 1.

Table 1.1 Preliminary Designated Locations for Baseline Noise Monitoring

ID Location Description

1 Shui Hau Village

2 Residences at Tong Fuk

3 Residences at Cheung Fu Street

4 Cheung Sha Ha Tsuen

5 San Shek Wan

6 Pui O Lo Wai Tsuen

7 Residences at Ham Tin

The monitoring location was normally at a point 1 m from the exterior of the

noise sensitive facade and be at a position 1.2 m above ground. If there is a

problem with access to the normal monitoring position, an alternative position

was chosen, and a correction to the measurement results was made. For

reference, a correction of +3dB(A) was made to free-field measurements.

The baseline noise monitoring was undertaken continuously for a period of 24

hours for one day at each location. The baseline noise levels were measured at

a minimum logging interval of 30 minutes for daytime (between 0700 and

1900 hours of normal weekdays) and 15 minutes (as three consecutive Leq, (5

minutes) readings) for evening time (between 1900 and 2300 hours on normal

weekdays), general holidays including Sundays (between 0700 and 2300

hours) and night-time (between 2300 and 0700 on all days). The Leq, L10 and

L90 were recorded at the specified interval.

Any non-project related construction activities in the vicinity of the

monitoring locations during the baseline monitoring were noted and the

source and location of such activities recorded.

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Figure no.

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OUTLYING ISLANDS SEWERAGE STAGE 2SOUTH LANTAU SEWERAGE WORKS -

INVESTIGATION

THE GOVERNMENT OF THEHONG KONG

SPECIAL ADMINISTRATIVE REGIONDRAINAGE SERVICES DEPARTMENT

香港特別行政區政府渠務署

Title

B L A C K & VE AT C H H O N G K ON G L I M I T ED

File: T:\GIS\CONTRACT\0227541\Mxd\NSR\0227541_NSR.mxdDate: 25/7/2014

Study Area for Noise, Noise Sensitive Receivers and Prevailing Background Noise Measurement Locations

Figure 8.1a

Prepared

Date Scale0 1 20.5Kilometers´

Key

!( Noise Sensitive Receiver

300m Study Area

Project Boundary

Proposed Site of Pumping Station

Alternative Site of Pumping Station

Proposed Site of Sewage Treatment Works

Proposed Sewer

Proposed Submarine Outfall

Proposed Rising Main

Access Road Lantau Island

N1

N2

N4

N3

N5 N6

N8

N7 N10

N12

N11

N13 N15

N17

N14

N16

TONGFUK MIU

WAN

SHUI HAU WAN

CHEUNG SHA BEACH

PUI O WAN

ID Location Description 1 Shui Hau Village 2 Residences at Tong Fuk3 Residences at Cheung Fu Street4 Cheung Sha Ha Tsuen5 Cheung Sha Ha Tsuen (East of Beach)6 San Shek Wan7 Residences at Ham Tin

1. Shui Hau Village

2. Residences at Tong Fuk

6. San Shek Wan

3. Residences at Cheung Fu Street

5. Cheung Sha Ha Tsuen (East)4. Cheung Sha Ha Tsuen

7. Residences at Ham Tin