8.1
This Section presents an
assessment of the potential noise impacts pertinent to the construction and
operation of the Project. The noise impact assessment has been conducted in accordance with the requirements as
set out in Annexes 5 and 13 of the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) as well as
Clause
Environmental
Legislation, Policies, Plans, Standards and Criteria
8.2
Noise impacts have
been assessed in accordance with the criteria and
methodology given in the Technical
8.3
The NCO provides the statutory
framework for noise control. This defines statutory limits applicable to
equipments used during the
construction and operation phases of the Project. The NCO invokes four
Technical
·
Technical
·
Technical
·
Technical
·
Technical
8.4
The NCO and the accompanying
Technical
8.5 With regard to the assessments of impacts caused by restricted-hour construction noise and operation noise, the NCO designates acceptable noise levels for Noise Sensitive Receivers (NSRs) on the basis of an Area Sensitivity Rating (ASR). The ASRs are based on the characteristics of the area within which they are located, e.g. rural, village, low-density residential, or urban (Table 8.1). Within these areas, the presence of "influencing factors" (such as the presence of industrial activities or major roads) can further affect the ASR and subsequently the acceptable noise level.
Table 8.1 Area Sensitivity Ratings (ASRs)
|
Type of Area Containing
NSR |
Degree to which NSR is
affected by Influencing Factor |
||
|
Not Affected |
Indirectly Affected |
Directly Affected |
|
|
Rural Area |
A |
B |
B |
|
Urban Area |
B |
C |
C |
|
Low density residential area consisting of low-rise or isolated
high-rise developments |
A |
B |
C |
|
Area other than those above |
B |
B |
C |
Construction Noise
8.6 Under the GW-TM, noise generated from construction activities is not restricted between 0700 and 1900 hours on weekdays, except public holidays. However, the EIAO-TM identifies a daytime general construction noise limit of 75 dB(A) for domestic premises and 70 dB(A) for educational institutions during normal teaching periods (65 dB(A) during examination periods). These standards are used as the assessment criteria for construction noise during non-restricted hours.
8.7 The NCO provides the statutory framework for controlling noise generated from construction works, other than percussive piling, using powered mechanical equipment (PME) between 1900 and 0700 hours on weekdays or at any time on Sundays as well as public holidays (i.e. restricted hours).
8.8 Between 1900 and 0700 hours and all day on Sundays and public holidays, activities involving the use of PME for the purpose of carrying out construction work is prohibited unless a construction noise permit (CNP) has been obtained. A CNP may be granted provided that the Acceptable Noise Level (ANL) for the NSRs can be complied with. ANLs are assigned depending upon the area sensitive rating (ASR). The corresponding ANLs for evening and night-time periods are given in Table 8.2.
Table 8.2 Acceptable Noise Levels for Construction Work (Restricted Hours)
|
Time Period |
Acceptable Noise Level (ANL) |
||
|
ASR A |
ASR B |
ASR C |
|
|
All days during the evening (1900 to 2300
hours), and general holidays (including Sundays) during the daytime and
evening (0700 to 2300 hours) |
60 |
65 |
70 |
|
Night (2300 to 0700 hours) |
45 |
50 |
55 |
8.9 It should be noted that the above assumed ASRs are for indicative assessment only. There is no guarantee that Construction Noise Permit (CNP) will be issued based on the description or assessment made in this EIA Report. The Noise Control Authority will only consider a well-justified and documented CNP application for construction works within restricted hours in accordance with the relevant Technical Memoranda issued under the NCO. The Noise Control Authority will take into account the existing adjoining land uses and any previous complaints against construction activities at the site before issuing the CNP with certain conditions. Failure to comply with such conditions will lead to cancellation of the CNP and the subsequent prosecution actions made under the NCO.
Operation Noise
8.10 Fixed noise sources associated with the Project would be controlled by the NCO and IND-TM. The Acceptable Noise Levels (ANL) is a function of the type of area in which the NSRs are located, and the degree of the effect on the NSRs affected by the influencing factors such as major roads and industrial areas. According to the IND-TM, the ANLs for different Area Sensitivity Ratings (ASRs) are given in Table 8.3.
Table 8.3 Acceptable Noise Levels for Fixed Noise Sources
|
Time Period |
Acceptable
Noise Level (ANL) |
||
|
ASR A |
ASR B |
ASR C |
|
|
Daytime and Evening (0700 to 2300 hours) |
60 |
65 |
70 |
|
Night (2300 to 0700
hours) |
50 |
55 |
60 |
8.11 In any event, the above Area Sensitivity Ratings are for indicative assessment only. It should be noted that the fixed noise sources are controlled under Section 13 of the NCO. At the time of investigation, the Noise Control Authority shall determine the noise impact from the concerned fixed noise sources on the basis of prevailing legislation and practices being in force, and taking into account the existing adjoining land uses. Nothing in the EIA Report shall bind the Noise Control Authority in the context of law enforcement against all the fixed noise sources being assessed.
8.12 The NSRs are located in the area other than rural area, low density residential area and urban area, and they are not affected by influencing factors (i.e. industrial activities or major roads). With reference to Table 8.1 above, ASR of “B” has been assumed for the NSRs in the vicinity of the proposed Project site. The EIAO-TM recommends that the level of the intruding noise at the façade of the nearest sensitive use should be at least 5 dB(A) below the appropriate ANL or, in the case of background noise being 5 dB(A) lower than the ANL, the predicted noise level arising from the operation of the proposed Project at the façade of the nearest sensitive use should not exceed the background noise level.
Description of the
Environment
Existing
Noise Environment
8.13 Part of the Project site at Siu Ho Wan is currently occupied by a private concrete batching plant and it is to be decommissioned and made available by 2011.
8.14
As shown in Figure
1.1, major land uses in the
close vicinity of the Project site are of industrial nature, which are not
regarded as noise sensitive uses according to Annex 13 of EIAO-TM. The Project
Site is located adjacent to the
8.15
The existing noise environment
for the study area is dominated by the road traffic along the
Noise Sensitive Receivers
8.16
In accordance with Clause
8.17 To evaluate the potential construction and operation noise impacts arise from the Project, representative NSR(s) have been identified with reference to the relevant land use plans, site observations, and in accordance with the EIAO-TM.
8.18
Relevant land
use plans of i) Siu Ho Wan
Layout Plan – Lantau Island (L/I-SHW/1)
adopted on 25 January 2002; and ii) Revised Concept
Plan for Lantau published in May 2007 have been
studied. It
is noted that no planned/committed noise sensitive
development is identified in
the study area, while the
nearest noise sensitive uses to the Project Site is the
Identification of Environmental Impacts
Construction
Noise
8.19 Since the existing site surface is paved with concrete and at an appropriate level for the construction of OWTF, extensive site formation works would not be required. The potential source of noise impact during the construction phase of the Project would be the use of PMEs for various construction activities, including minor excavation works, construction of superstructure for the office and storage, and installation of treatment facilities. PMEs likely to be used include breaker, crane, lorry, excavator, air compressor, generator and piling machines.
8.20 Under normal conditions, construction activities for the Project would be carried out during non-restricted hours (0700-1900 hours) on normal working days. In the case of any activities that have to be carried out during restricted hours, it is the Contractor’s responsibility to ensure compliance with the NCO as well as the relevant TMs. The Contractor will be required to submit application for the CNP and abide by the conditions set out by the Noise Control Authority.
8.21 The construction period of OWTF is estimated to be from May 2012 to March 2013. Within this period, the HyD’s project “Further Landscape Enhancement Works to North Lantau Highway” would be commenced in May 2010 and ended in November 2012. Since the work area for landscape enhancement works would be limited, it is expected that the potential noise impact from this concurrent project would be insignificant. Two WSD’s projects “Extension of Siu Ho Wan Water Treatment Works” and “Integration of Siu Ho Wan and Silver Mine Bay Water Treatment Works” may be commenced in early March 2013. Since the overlapping would be 1 – 2 months and the construction of OWTF would be almost completed at this stage, no adverse cumulative noise impacts would be anticipated.
Operation
Noise
8.22 During the operation phase of the Project, the main potential sources of noise would be generated from the movements of waste collection vehicles, and the operation of waste treatment facilities (such as shedders, feed pumps, mixing drums) as well as gas engine generator sets (Cogen Units). Since all the waste reception, pre-treatment, digestion and post-treatment activities will be undertaken in enclosed buildings, noise impacts from the operation of OWTF is anticipated to be insignificant.
Evaluation of
Environmental Impacts
8.23
As discussed in Section 8.18, it is noted that no existing or planned sensitive receivers are identified within
Mitigation of Adverse Environmental Impacts
8.24 In view of the Project’s negligible noise impact to the NSR, specific noise mitigation measures for the construction and operation phases of the Project would not be required.
Environmental Monitoring and Audit
8.25 With no adverse noise impact on the NSR expected, noise monitoring is therefore not considered necessary. Nevertheless, the Contractor shall implement good site practice throughout the construction period to minimise the noise nuisance as far as practicable.
8.26
The noise impacts have
been assessed accordingly in
accordance with the criteria and methodology given in
the Technical
8.27
In accordance with Clause
8.28 Since the nearest noise sensitive receiver is located considerably distant from the Project site and is substantially screened by natural terrain, the noise impact caused by the Project itself and any cumulative noise impact associated with the Project is thus considered insignificant. In this regard, no specific mitigation measures are recommended and subsequently no requirements on noise monitoring would be set out in the EM&A manual.