4.2 Environmental Legislation, Standards and Criteria.. 4-1

4.3 Description of the Environment. 4-3

4.4 Noise Sensitive Receivers.. 4-3

4.5 Identification of Environmental Impacts.. 4-4

4.6 Assessment Methodology.. 4-5

4.7 Prediction and Evaluation of Environmental Impacts.. 4-6

4.8 Mitigation of Adverse Environmental Impacts.. 4-7

4.9 Evaluation of Residual Impacts.. 4-11

4.10 Environmental Monitoring and Audit. 4-11

4.11 Conclusion.. 4-12

List of Tables

Table 4.1 Daytime Construction Noise Criteria

Table 4.2 Area Sensitivity Ratings

Table 4.3 Acceptable Noise Level for Fixed Plant Noise

Table 4.4 Representative Noise Sensitive Receivers

Table 4.5 Summary of Predicted Construction Noise Levels without Mitigation Measures

Table 4.6 Summary of Predicted Fixed Plant Noise Levels without Mitigation Measures

Table 4.7 Proposed Quiet PME for the Project

Table 4.8 Predicted Construction Noise Levels at Representative Noise Sensitive Receivers – Mitigated Scenario

Table 4.9 Predicted Cumulative Construction Noise Levels at Representative Noise Sensitive Receivers – Mitigated Scenario

Table 4.10 Predicted Fixed Plant Noise Level with Mitigation Measures

List of Figures

Figure 4.1 Location of the Representative Noise Sensitive Receivers

List of Appendices

Appendix 4.1 Determination of Fixed Plant Noise Criteria

Appendix 4.2 Identified Noise Sensitive Receivers within Assessment Area

Appendix 4.3 Photographs of Representative Noise Sensitive Receivers

Appendix 4.4 Proposed Construction Plant Inventory without Mitigation Measures

Appendix 4.5 Proposed Operational Fixed Plant Inventory without Mitigation Measures

Appendix 4.6 Calculations of Construction Noise Levels without Mitigation Measures

Appendix 4.7 Calculations of Operational Fixed Plant Noise Levels without Mitigation Measures

Appendix 4.8 Proposed Construction Plant Inventory with Mitigation Measures

Appendix 4.9 Calculations of Construction Noise Levels with Mitigation Measures

Appendix 4.10 Cumulative Construction Noise Impact

Appendix 4.11 Proposed Operational Fixed Plant Inventory with Mitigation Measures

Appendix 4.12 Calculations of Operational Fixed Plant Noise Levels with Mitigation Measures

4. NOISE

4.2 Environmental Legislation, Standards and Criteria

4.2.1 General

4.2.1.1 Noise impacts were assessed in accordance with the criteria and methodology given in the Technical Memoranda (TMs) issued under the Noise Control Ordinance (Cap. 400) (NCO) and Annexes 5 and 13 in the EIAO-TM.

4.2.1.2 The NCO, and Environmental Impact Assessment Ordinance (Cap. 499) (EIAO) provide the statutory framework for noise control. Assessment procedures and standards are set out in the following TMs:

· EIAO-TM

· Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM)

· Technical Memorandum on Noise form Construction Work in Designated Areas (DA-TM)

· Technical Memorandum for the Assessment of Noise from Places Other Than Domestic Premises, Public Places or Construction Sites (IND-TM)

4.2.2 Construction Noise

4.2.2.1 The NCO provides the statutory framework for noise control of construction work, other than percussive piling, using powered mechanical equipment (PME) between the hours of 1900 and 0700 hours or at any time on Sundays and general holiday (i.e. restricted hours). Noise control on construction activities taking place at other times is subject to the “Noise Standards for Daytime Construction Activities” in Table 1B of Annex 5 in the EIAO-TM. The criteria are summarized in Table 4.1.

Table 4.1 Daytime Construction Noise Criteria

Uses	Daytime Noise Criteria, L_{eq, 30min,} dB(A)
Domestic premises, hotel, hostel	75
Educational Institution	70
Educational Institution (during examination)	65

Note: The above standards apply to uses which rely on opened windows for ventilation.

4.2.2.2 Based on the currently envisaged construction programme, no work will be required in restricted hours as defined under the NCO. In case of any construction activities during restricted hours, it is the contractor’s responsibility to ensure compliance with the Construction Noise Permit (CNP) and the relevant TMs under the NCO. The contractor will be required to submit CNP application to the Noise Control Authority and abide by any conditions stated in the CNP, should one be issued. Regardless of the results of construction noise impact assessment in this EIA study, the Noise Control Authority will process Construction Noise Permit (CNP) application, if necessary, based on the NCO, the relevant technical memoranda issued under the NCO, and the contemporary conditions/ situations.

4.2.3 Operational Noise

4.2.3.1 Fixed plant noise emitted from the operation of proposed Project is controlled by the NCO and IND-TM. With regard to the assessment of the operational noise impacts, the NCO designates Acceptable Noise Levels (ANLs) for noise sensitive receivers (NSRs) on the basis of an Area Sensitivity Rating that is based on the characteristics of the area within which the NSRs are located, such as rural, village, low-density residential, or urban. The presence of "Influencing Factors" (IFs), which include the Hong Kong International Airport, industrial area or major roads with an annual average daily traffic flow in excess of 30,000, can further affect the Area Sensitivity Ratings and hence the ANL as shown in Table 4.2.

Table 4.2 Area Sensitivity Ratings

Type of Area Containing NSR	Degree to which NSR is affected by Influencing Factor
Type of Area Containing NSR	Not Affected	Indirectly Affected	Directly Affected
Rural area, including country parks or village type developments	A	B	B
Low density residential area consisting of low-rise or isolated high-rise developments	A	B	C
Urban area	B	C	C
Area other than those above	B	B	C

4.2.3.2 According to the IND-TM, the ANLs for different Area Sensitivity Ratings during different periods are given in Table 4.3.

Table 4.3 Acceptable Noise Level for Fixed Plant Noise

Time Period	ANL L_{eq 30-min}, dB(A)
Time Period	ASR A	ASR B	ASR C
Day (0700 to 1900 hours)	60	65	70
Evening (1900 to 2300 hours)	60	65	70
Night (2300 to 0700 hours)	50	55	60

4.2.3.3 The assessment area for the noise impact assessment is defined by a distance of 300 m from the boundary of the Project Site. No IFs were identified in the vicinity of the Project. Four existing representative noise sensitive receivers (NSRs), Hong Kong Baptist Theological Seminary (HKBTS) Staff & Students Quarters (N1a & N1b), HKBTS Administration and Education Block (N2), Block 11 of Symphony Bay (N4) and Zessa Vista (N5), as well as one planned NSR, Planned School with Recreational Area under the Approved Planning Application No. A/MOS/125 (N3a & N3b), were identified within the assessment area as described in Section 4.4 and detailed in Table 4.4. The Area Sensitivity Rating for NSRs N1a, N1b, N2, N3a and N3b is rated as “B” as they are located in area regarded as area other than urban, rural and low-density residential area and would not be affected by any IFs. For NSR N4, they belong to low density residential area consisting of low-rise developments with no IFs in the vicinity, therefore, the Area Sensitivity Rating for NSR N4 is determined as “A”. For NSR N5, it is a village type development with no IFs in the vicinity, an Area Sensitivity Rating of “A” has been assigned.

4.2.3.4 As stipulated in Annex 5 of the EIAO-TM, the noise standard for planning purposes for fixed noise source are (a) 5 dB(A) below the appropriate ANL shown in Table 3 of the IND-TM, or (b) the prevailing background noise levels (for quiet areas with level 5 dB(A) below the ANL). In this regard, a noise survey in the vicinity of the representative NSRs was conducted in October 2020 to determine the background noise levels. The survey results were compared with the ANL-5 dB(A) criteria to determine the noise criteria to be adopted in this EIA Report. Locations of noise measurement points and measured background noise levels, as well as the assessment criteria for the proposed fixed noise sources of the Project, as adopted in this EIA Report, are presented in Appendix 4.1.

4.2.3.5 In any event, the Area Sensitivity Ratings assumed in this EIA Report is for indicative assessment only. It should be noted that fixed noise sources are controlled under Section 13 of the NCO. At the time of investigation, the Noise Control Authority shall determine noise impact from concerned fixed noise sources on the basis of prevailing legislation and practices being in force, and taking account of contemporary conditions / situation of adjoining land uses. Nothing in this EIA Report shall bind the Noise Control Authority in the context of law enforcement against all the fixed noise sources being assessed.

4.3 Description of the Environment

4.3.1.1 The proposed Sai O Trunk Sewer SPS falls within a site zoned as “Government, Institution or Community” (“G/IC”) on the draft Ma On Shan Outline Zoning Plan No. S/MOS/23. It is located north to Sai O Offtake and Pigging Station, southeast to a planned school with recreational area under the approved planning application No. A/MOS/125, and northeast to HKBTS and Nin Ming Road as illustrated in Figure 4.1. The nearby residential dwellings are either urban private estates or village-type.

4.4 Noise Sensitive Receivers

4.4.1.1 All existing and planned / committed NSRs in the assessment area were identified (Appendix 4.2 refers) according to the criteria set out in Annex 13 of the EIAO-TM, observations from site visits and review of relevant land use plans including Outline Zoning Plans (OZP), information available in the Statutory Planning Portal of the Town Planning Board (TPB) and land status plans published by Lands Department. Four representative NSRs for the construction phase and five for operational phase were identified as shown in Figure 4.1. Details of the representative NSRs are presented in Table 4.4 and their photos are shown in Appendix 4.3.

Table 4.4 Representative Noise Sensitive Receivers

ID	Description	Land Use	No. of Storey	Shortest Horizontal Distance to Site Boundary, m	Construction Phase NSR	Operational Phase NSR
N1a	HKBTS Staff & Students Quarters	Residential	6	20	Yes	Yes
N1b	HKBTS Staff & Students Quarters	Residential	6	20	Yes	Yes
N2	HKBTS Administration and Education Block	Education	5	31	Yes	Yes
N3a	Planned School with Recreational Area under the Approved Planning Application No. A/MOS/125	Education	6	30	No ⁽¹⁾	Yes
N3b		Education	6	51	No ⁽¹⁾	Yes
N4	Symphony Bay Block 11	Residential	7	174	Yes	Yes
N5	Zessa Vista	Residential	3	227	Yes	Yes

Note:

(1) No confirmed construction programme of the planned NSR is available at the time of the preparation of this EIA. It is therefore assumed that the planned NSR would not exist during construction phase of the Project and hence it is only considered as NSR during operation phase.

4.5 Identification of Environmental Impacts

4.5.2 Operational Phase

4.5.2.1 During operational phase, fixed plant noise from the operation of the proposed Sai O Trunk Sewer SPS would be the major source of noise impacts. Based on the current design as described in Section 2.3, the loading/unloading area would be enclosed to avoid noise nuisance from the loading and unloading activities during operation of the proposed Sai O Trunk Sewer SPS. No marine transportation of waste generated from operation of the SPS is expected. The major fixed noise sources of the proposed SPS would include submersible pumps, mechanically raked screens, ventilation fans and an exhaust fan of the deodorizing unit, along with a set of transformers in the transformer room. Since there were no other fixed plant noise sources identified in the vicinity of the proposed SPS at the time of the preparation of this EIA, cumulative impact would not be expected.

4.6 Assessment Methodology

4.6.1 Construction Phase

4.6.1.1 The methodology for the construction noise impact assessment follows the procedures outlined in the GW-TM. The general approach is summarized below:

· Locate the NSRs which would most likely be affected by noise from the construction work;

· Determine the items of PME for each discrete construction activity, based on available information or agreed plant inventories;

· Assign sound power levels (SWLs) to the proposed PME according to the GW-TM or other sources;

· Calculate distance attenuation and screening effects to NSRs from notional noise source;

· Predict construction noise levels at NSRs in the absence of any mitigation measures;

· Consider cumulative impact from concurrent projects within 300 m of the NSRs, if any; and

· Compare the cumulative construction noise level against the corresponding noise criterion and propose suitable mitigation measures where necessary.

4.6.1.2 The assessment of construction noise was undertaken based on standard acoustic principles. SWLs of equipment were taken from Table 3 of the GW-TM and “Sound power levels of other commonly used PME” issued by EPD. Where no relevant SWL can be found in the GW-TM and other PME, reference is made to the information relating to Quality Powered Mechanical Equipment (QPME) available at EPD’s website^{^[1]} or PME specification published by equipment manufacturer. Groups of PME were assigned for various construction activities of the proposed Project. The plant inventory and utilization of on-time percentage of the PME is presented in Appendix 4.4. The tentative construction programme is presented in Appendix 2.5. The Project Proponent has confirmed that the proposed plant inventories as being practical and adequate for completing the works within the scheduled timeframe.

4.6.1.3 The assessment was undertaken based on the assumption that all items of construction equipment would be located at a notional noise source point for each construction activity and that all items of equipment would be operating simultaneously. The sound pressure level (SPL) of each construction task has been calculated, depending on the number of plant items involved and the distance from the NSR. A positive 3 dB(A) façade correction has been added to the predicted noise levels to account for the façade effect at each assessment point. The noise levels at the NSRs have then been predicted by adding up the SPLs of all concurrent construction tasks from the Project and other concurrent projects identified during the EIA study within the assessment area. Notional sources that are at distances greater than 300 m from the NSRs have been excluded from the assessment.

4.6.1.4 The unmitigated construction noise impacts at the identified NSRs have been predicted accordingly. Practicable direct noise mitigation measures including the use of quieter equipment, movable noise barriers, noise barriers, enclosures and quieter alternative methods have been considered if exceedance of relevant noise standards is predicted. Appropriate correction factors for barrier effect would be adopted in accordance with Section 2.10 of the GW-TM. In cases where the mitigated noise levels still exceed the relevant criteria, the duration of noise exceedance would be estimated.

4.7 Prediction and Evaluation of Environmental Impacts

ID	Description	NSR Type	Predicted Unmitigated Construction Noise Level, dB(A) ⁽¹⁾
N1a	HKBTS Staff & Students Quarters	Residential	73 – 82
N1b	HKBTS Staff & Students Quarters	Residential	75 – 84
N2	HKBTS Administration and Education Block	Education	70 – 78
N4	Symphony Bay Block 11	Residential	60 – 68
N5	Zessa Vista	Residential	59 – 67

(1) Bolded values indicate exceedance of EIAO-TM noise criteria of 75 dB(A) for residential dwellings, or 70 dB(A) for educational institution during normal school days; while underlined value indicates exceedance of EIAO-TM noise criteria of 65 dB(A) for educational institution during examination period.

4.7.2 Operational Phase

4.7.2.1 The fixed plant noise levels from the normal operation of the proposed Sai O Trunk Sewer SPS were predicted by adopting the methodology in Section 4.6.2. The predicted fixed plant noise levels under unmitigated scenario are summarised in Table 4.6. with details of the calculations given in Appendix 4.7.

Table 4.6 Summary of Predicted Fixed Plant Noise Levels without Mitigation Measures

ID	Description	Noise Criteria, dB(A)		Predicted Fixed Plant Noise Level, L_{eq 30-min} dB(A) ⁽¹⁾
ID	Description	Daytime / Evening	Night-time
N1a	HKBTS Staff & Students Quarters	44	41	44 - 45
N1b	HKBTS Staff & Students Quarters	44	41	46
N2	HKBTS Administration and Education Block	44	N/A⁽²⁾	40
N3a	Planned School with Recreational Area under the Approved Planning Application No. A/MOS/125	42	N/A⁽²⁾	42
N3b		42	N/A⁽²⁾	41 – 42
N4	Symphony Bay Block 11	44	41	31
N5	Zessa Vista	44	41	38

Notes:

(1) Bolded values denote exceedance of EIAO-TM criteria during daytime & evening and underlined values denote exceedance of EIAO-TM criteria during night-time.

(2) The NSR is for educational use and night-time (2300 to 0700) use is not expected. Hence, only the noise criteria for daytime / evening (0700 to 2300 hrs) is adopted.

4.7.2.2 As shown in Table 4.6, exceedances of fixed plant noise criteria were predicted during operation of the SPS. Hence, noise mitigation measures are considered necessary to alleviate the fixed plant noise impact on the affected NSRs.

4.8 Mitigation of Adverse Environmental Impacts

4.8.1 Construction Phase

4.8.1.1 In view of the predicted noise exceedances during the construction of the Project, the following mitigation measures have been considered:

· Good site practice;

· Use of quiet PME;

· Adoption of temporary noise barriers/acoustic mat; and

· Scheduling of noisy activities.

Good Site Practice

4.8.1.2 Although the noise mitigation effects are not easily quantifiable, and the benefits may vary with site conditions and operating conditions, good site practices are easy to implement and do not impact upon the works schedule. The site practices listed below should be followed during construction works:

· Only well-maintained PME to be operated on-site and should be serviced regularly during construction works;

· Silencers or mufflers on construction equipment should be utilized (if appropriate) and should be properly maintained during the construction;

· Mobile plant, if any, should be sited as far away from NSRs as possible;

· Machines and plant (such as trucks) that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

· Plant known to emit noise strongly in one direction should, wherever possible, be orientated to direct noise away from the nearby NSRs; and

· Material stockpiles and other structures should be effectively utilised, wherever practicable, in screening noise from on-site construction activities.

Use of Quiet PME

4.8.1.3 The use of quiet PME is considered a practicable means to mitigate the construction noise impact. Quiet plant is defined as a PME having actual SWL lower than the value specified in the GW-TM. The type of quiet PME adopted in this assessment is for reference only. The Contractors may adopt alternative quiet PME as long as it can be demonstrated that they would not result in construction noise impacts worse than those predicted in this assessment.

4.8.1.4 For the use of quiet plant associated with the construction works, reference has been made to QPME list available on the EPD website, which provides the SWLs for specific quiet PME or PME specification published by equipment manufacturer. The quiet PME and the associated SWLs adopted in the assessment are listed in Table 4.7.

Table 4.7 Proposed Quiet PME for the Project

PME	Reference ⁽¹⁾	SWL, dB(A)
Air compressor, air flow >10 m³/min and ≦30 m³/min	QPME EPD-05791 or equivalent	98
Backhoe	QPME EPD-06284 or equivalent	99
Breaker, hand-held, mass > 35kg	QPME EPD-07425 or equivalent	103
Mobile Crane	QPME EPD-05808 or equivalent	92
Roller, Vibratory	QPME EPD-07283 or equivalent	103

Note:

(1) Quality Powered Mechanical Equipment (QPME) system by EPD (http://www.epd.gov.hk/cgi-bin/npg/qpme/search_gen.pl?lang=eng&st=sim&valid=Y)

Use of Movable Noise Barriers/Acoustic Mats

4.8.1.5 Movable noise barriers that can be placed close to the construction equipment and moved along with the PME are effective for screening noise from NSRs. A typical design which has been used locally is a wooden framed barrier with a cantilevered upper portion of superficial density no less than 10 kg/m² on a skid footing with internal sound absorptive lining. This measure is particularly effective for low level zone of NSRs. A longer cantilevered top cover would be required to achieve screening benefits at upper floors of NSRs. The Contractor shall be responsible for the design and actual position of the movable noise barriers with due consideration given to the position and size of the PME, and the requirement of intercepting the line-of-sight from the NSRs to the PME, as well as ensuring that the barriers should have no opening and gap. It is anticipated that properly designed noise barriers would achieve a 5 dB(A) reduction for mobile PME and a 10 dB(A) reduction for static PME. Acoustic mat with surface mass of not less than 7kg/m² would be used for plant items such as piling, oscillator and a 10 dB(A) noise reduction is anticipated.

4.8.1.6 The plant inventory for the assessment of the mitigated scenario is presented in Appendix 4.8.

Scheduling of Noisy Activities to Avoid Noise Impact on N2

4.8.1.7 To minimise the construction noise impact on N2, the use of piling (oscillator) in ELS and concurrent use of concrete lorry mixer with other PMEs in steel fixing and concreting of structure should be avoided during the examination period of N2. The Contractor should keep close communication with the operator of HKBTS to obtain the updated schedule of examination at the time of conducting the relevant construction works.

Mitigated Construction Noise Levels

4.8.1.8 With the implementation of the recommended mitigation measures, the noise levels at all the representative NSRs would comply with the EIAO-TM daytime noise criteria. The predicted mitigated construction noise levels at the representative NSRs are summarized in Table 4.8 with details of the calculation provided in Appendix 4.9.

Table 4.8 Predicted Construction Noise Levels at Representative Noise Sensitive Receivers – Mitigated Scenario

ID	Description	NSR Type	Predicted Construction Noise Level, L_{eq 30-min} dB(A)
N1a	HKBTS Staff & Students Quarters	Residential	62 – 70
N1b	HKBTS Staff & Students Quarters	Residential	64 - 72
N2	HKBTS Administration and Education Block	Education	59 – 66 (59 – 65 during examination period)
N4	Symphony Bay Block 11	Residential	49 – 56
N5	Zessa Vista	Residential	48 – 54

Cumulative Impact from Concurrent Project

4.8.1.9 As discussed in Section 4.5.1, the only concurrent project that may pose cumulative construction noise impacts would be the “Sai Sha Road Widening”. Based on the information available at the time of preparing this EIA report, some construction activities of “Sai Sha Road Widening” would overlap with the Project from Q4 2021 to Q4 2023.

4.8.1.10 Based on the construction noise assessment for “Sai Sha Road Widening”, the maximum noise level during the overlapping period (i.e. the levelling and formation of road sub-base) has been adopted for assessing the cumulative construction noise impact as the worst-case scenario. The predicted cumulative construction noise levels at the representative NSRs are summarized in Table 4.9. Details of the cumulative construction noise impact assessment are presented in Appendix 4.10.

Table 4.9 Predicted Cumulative Construction Noise Levels at Representative Noise Sensitive Receivers – Mitigated Scenario

ID	Description	NSR Type	Maximum Cumulative Construction Noise Level, L_{eq 30-min}dB(A)
N1a	HKBTS Staff & Students Quarters	Residential	70
N1b	HKBTS Staff & Students Quarters	Residential	74
N2	HKBTS Administration and Education Block	Education	66 (65 during examination period)
N4	Symphony Bay Block 11	Residential	59
N5	Zessa Vista	Residential	65

4.8.1.11 As shown in Table 4.9, the cumulative construction noise levels at all the representative NSRs would comply with EIAO-TM daytime construction noise criteria.

4.8.2 Operational Phase

4.8.2.1 While the submersible pumps, mechanically raked screens and transformer set would be confined inside the structures of the proposed Sai O Trunk Sewer SPS with 200mm thick reinforced concrete structure and soundproof door, to mitigate the operation noise levels from the proposed Sai O Trunk Sewer SPS, it is recommended to install silencers or other acoustic treatment equipment at the outlet of the ventilation fans and exhaust fan of the deodorizing unit, which openings would be facing away from the nearest NSRs, i.e. towards to the eastern side of the SPS. With reference to “Good Practices on Ventilation System Noise Control” published by EPD, the installation of silencers could achieve noise reduction up to 10 dB(A) and therefore -10 dB(A) correction is applied in this assessment. The operational fixed plant noise inventory under the mitigated scenario is shown in Appendix 4.11.

4.8.2.2 The mitigated fixed plant noise level from the proposed Sai O Trunk Sewer SPS at the selected NSRs were calculated and summarized in Table 4.10 below. As no noticeable existing, planned or committed fixed noise sources were identified in the vicinity of the Project site during the preparation of the EIA, no cumulative fixed plant noise impacts would be anticipated. With the proposed mitigation measure in place, the predicted fixed plant noise levels during operation of the Sai O Trunk Sewer SPS at all the selected NSRs would comply with the noise criteria. Detailed calculations are presented in Appendix 4.12.

Table 4.10 Predicted Fixed Plant Noise Level with Mitigation Measures

ID	Description	Noise Criteria, L_{eq 30-min}, dB(A)		Predicted Fixed Plant Noise Level, L_{eq 30-min}, dB(A)
ID	Description	Daytime / Evening	Night-time
N1a	HKBTS Staff & Students Quarters	44	41	36 – 37
N1b	HKBTS Staff & Students Quarters	44	41	37 – 38
N2	HKBTS Administration and Education Block	44	N/A⁽¹⁾	32
N3a	Planned School with Recreational Area under the Approved Planning Application No. A/MOS/125	42	N/A⁽¹⁾	35
N3b		42	N/A⁽¹⁾	35
N4	Symphony Bay, Block 11	44	41	24
N5	Zessa Vista	44	41	29

Note:

(1) The NSR is for educational use and night-time (2300 to 0700) use is not expected. Hence, only the noise criteria for daytime / evening (0700 to 2300 hrs) is adopted.

4.8.2.3 As shown in Table 4.10, all the predicted fixed plant noise levels at the representative NSRs would comply with the fixed plant noise criteria with the implementation of noise mitigation measure, namely silencers or other acoustic treatment equipment at the outlet of the ventilation fans and exhaust fan of the deodorizing unit. Nonetheless, the following best practices should be implemented as far as practicable to further minimise any potential impacts:

· Quieter plant should be chosen as far as practicable;

· Include noise levels specification when ordering new plant items;

· All openings, including louvres for ventilation and machine room doors should be oriented away from the NSRs as far as practicable;

· Silencers, acoustic louvres or acoustic doors should be used where necessary; and

· Develop and implement a regularly scheduled plant maintenance programme so that plant items are properly operated and serviced. The programme should be implemented by properly trained personnel.

4.9 Evaluation of Residual Impacts

4.9.1 Construction Phase

4.9.1.1 With the implementation of the recommended noise mitigation measures, including adoption of good site practice, the use of quiet PME, movable noise barriers/acoustic mats and proper scheduling of noisy activities, construction noise levels at all representative NSRs would comply with EIAO-TM daytime construction noise criteria. No residual construction noise impact is anticipated.

4.9.2 Operational Phase

4.9.2.1 With proper implementation of the recommended mitigation measure, i.e. provision of silencers or other acoustic treatment equipment at the outlet of the ventilation fans and exhaust fan of the deodorizing unit, no residual noise impact is anticipated during the operational phase of the Project.

4.10 Environmental Monitoring and Audit

4.10.1 Construction Phase

4.10.1.1 Noise monitoring is recommended as part of the environmental monitoring and audit (EM&A) programme for the construction phase of the Project to check compliance with the daytime construction noise criteria. The implementation of the recommended mitigation measures for daytime construction activities should also be audited as part of the EM&A programme. Details of the EM&A requirements are provided in the EM&A Manual.

4.10.2 Operational Phase

4.10.2.1 No adverse noise impact would be anticipated during operation of the Project with proper implementation of the proposed mitigation measures. Commissioning test should be conducted prior to operation of the Project to ensure fixed plant noise impact would comply with the relevant noise standards. Thus, no operational noise monitoring would be required.

4.11 Conclusion

4.11.1 Construction Phase

4.11.1.1 The assessment for the potential construction noise impact from the proposed Sai O Trunk Sewer SPS has been conducted. The assessment result indicated that the mitigated noise levels at all NSRs would comply with the noise criteria set out in the EIAO-TM with proper implementation of the proposed mitigation measures, including adoption of good site practices, use of quiet PME, movable noise barriers/acoustic mats and proper scheduling of noisy construction activities. No adverse noise impact is anticipated during construction phase of the Project.

4.11.2 Operational Phase

4.11.2.1 The noise impact associated with the operation of the Project has been assessed based on the plant inventory provided by the Project Engineer at the time of the assessment. The assessment result indicated that the predicted fixed plant noise levels at all representative NSRs would comply with the noise criteria with proper implementation of the proposed mitigation measures. No adverse noise impact is anticipated during operational phase of the Project.

[1] http://www.epd.gov.hk/epd/english/environmentinhk/noise/qpme/index.html

4. NOISE

4.1 Introduction

4.2 Environmental Legislation, Standards and Criteria

4.2.1 General

4.2.1.1 Noise impacts were assessed in accordance with the criteria and methodology given in the Technical Memoranda (TMs) issued under the Noise Control Ordinance (Cap. 400) (NCO) and Annexes 5 and 13 in the EIAO-TM.

4.2.1.2 The NCO, and Environmental Impact Assessment Ordinance (Cap. 499) (EIAO) provide the statutory framework for noise control. Assessment procedures and standards are set out in the following TMs:

4.2.2 Construction Noise

4.2.3 Operational Noise

4.2.3.2 According to the IND-TM, the ANLs for different Area Sensitivity Ratings during different periods are given in Table 4.3.

4.3 Description of the Environment

4.4 Noise Sensitive Receivers

4.5 Identification of Environmental Impacts

4.5.1 Construction Phase

4.5.2 Operational Phase

4.6 Assessment Methodology

4.6.1 Construction Phase

4.6.1.1 The methodology for the construction noise impact assessment follows the procedures outlined in the GW-TM. The general approach is summarized below:

4.6.2 Operational Phase

4.6.2.4 Based on the design information, all ventilation fans of the proposed Sai O Trunk Sewer SPS including the exhaust fan of the deodorizing unit would be located at the eastern façade of the SPS. It is assumed in the assessment that all on-duty equipment would be operated 24 hours per day.

4.7 Prediction and Evaluation of Environmental Impacts

4.7.1 Construction Phase

4.7.1.1 For normal daytime working hours, the noise impacts arising from different construction activities without mitigation measures have been predicted. Details of the unmitigated construction noise assessment are presented in Appendix 4.6 with the results summarized in Table 4.5.

4.7.2 Operational Phase

4.7.2.2 As shown in Table 4.6, exceedances of fixed plant noise criteria were predicted during operation of the SPS. Hence, noise mitigation measures are considered necessary to alleviate the fixed plant noise impact on the affected NSRs.

4.8 Mitigation of Adverse Environmental Impacts

4.8.1 Construction Phase

4.8.1.1 In view of the predicted noise exceedances during the construction of the Project, the following mitigation measures have been considered:

4.8.1.6 The plant inventory for the assessment of the mitigated scenario is presented in Appendix 4.8.

4.8.1.11 As shown in Table 4.9, the cumulative construction noise levels at all the representative NSRs would comply with EIAO-TM daytime construction noise criteria.

4.8.2 Operational Phase

4.9 Evaluation of Residual Impacts

4.9.1 Construction Phase

4.9.2 Operational Phase

4.10 Environmental Monitoring and Audit

4.10.1 Construction Phase

4.10.2 Operational Phase

4.11 Conclusion

4.11.1 Construction Phase

4.11.2 Operational Phase