3. airborne noise impact

Introduction

3.1 Potential airborne noise impacts likely to arise from the proposed Project during both the construction and operation phases have been evaluated and the results are presented in this section.

3.2 The following potential airborne noise impacts were assessed, and the predicted noise levels and necessary noise mitigation measures to control the impacts to within established criteria are presented in this section:

§ Construction noise

§ Operational phase fixed plant noise

Environmental Legislation, Standards and Guidelines

3.3 The Noise Control Ordinance (NCO) and Environmental Impact Assessment Ordinance (EIAO) provide the statutory framework for noise control. Assessment procedures and standards are set out in the five Technical Memoranda (TMs) listed below:

§ TM on Environmental Impact Assessment Process (EIAO-TM)

§ TM on Noise from Construction Work other than Percussive Piling (GW-TM)

§ TM on Noise from Percussive Piling (PP-TM)

§ TM on Noise form Construction Work in Designated Areas (DA-TM)

§ TM on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM)

3.4 Potential construction noise and fixed plant noise impacts arising from the Project have been assessed in accordance with the criteria and methodology given in the TMs made under the NCO and the EIAO.

3.5 It is noted that percussive piling is governed by the PP-TM and separate application to EPD for Construction Noise Permit (CNP) would be required.

Construction Noise

Noise Standards for Non-restricted Hours

EIAO-TM

3.6 Daytime construction noise (excluding percussive piling) between the hours 0700 – 1900 on weekdays, i.e. non-restricted hours, is controlled under the EIAO. Annex 5 of the EIAO-TM sets out the construction noise assessment limits, which are L_{eq(30 min)} 75dB(A) for domestic premises and L_{eq(30 min)} 70dB(A) for schools during normal hours (65dB(A) during examination periods) and all other places where unaided voice communication is required.

Noise Standards for Restricted Hours

3.7 Between 1900 and 0700 hours and all day on Sundays and public holidays, activities involving the use of powered mechanical equipment (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 in cases where the noise can be contained within the Acceptable Noise Level (ANL) at the NSRs. ANLs are assigned depending upon the Area Sensitivity Ratings (ASRs). The corresponding basic noise levels (BNLs) for evening and nighttime periods are given in Table 3.1.

Table 3.1 Construction Noise Criteria for Activity other than Percussive Piling

Time Period	Basic Noise Level (BNLs)
	ASR A	ASR B	ASR C
Evening (1900 to 2300 hours) ^(1)	60	65	70
Night (2300 to 0700 hours)	45	50	55

Notes: (1) Includes Sundays and Public Holidays during daytime and evening

3.8 Despite any description or assessment made in this EIA Report on construction noise aspects, there is no guarantee that a Construction Noise Permit (CNP) will be issued for the project construction. The Noise Control Authority will consider a well-justified CNP application, once filed, for construction works within restricted hours as guided by the relevant Technical Memoranda issued under the Noise Control Ordinance. The Noise Control Authority will take into account contemporary conditions/ situations of adjoining land uses and any previous complaints against construction activities at the site before deciding whether to grant a CNP. Nothing in this EIA Report should bind the Noise Control Authority in making its decision. If a CNP is to be issued, the Noise Control Authority should include in the permit any condition it thinks fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution under the NCO.

3.9 Under the TM on Noise from Construction Work in Designated Areas, the use of five types of Specified Powered Mechanical Equipment (SPME) and three types of Prescribed Construction Work (PCW) within a designated area during restricted hours would require a valid CNP. The SPME includes hand-held breaker, bulldozer, concrete lorry mixer, dump truck and hand-held vibratory poker. The PCW are:

· Erecting or dismantling of formwork or scaffolding.

· Loading, unloading or handling of rubble, wooden boards, steel bars, wood or scaffolding material.

· Hammering.

3.10 In general, it should not be presumed that a CNP would be granted for carrying out PCW within a designated area during restricted hours. The CNP may be granted for the execution of construction works during restricted hours involving the use of PME and/ or SPME if the relevant Acceptable Noise Levels and criteria stipulated in the GW-TM and DA-TM can be met.

3.11 As defined in the Noise Control Designated Area Plan, the whole WIL alignment and works areas except Works Areas E and F are within the Designated Area.

3.12 According to the construction programme, all the proposed construction works except for underground tunnelling work and the temporary magazine site would be carried out during non-restricted hours. In case of any construction activities during restricted hours, it is the Contractor’s responsibility to ensure compliance with the NCO and the relevant TMs. 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.

Blasting

3.13 There are no statutory procedures and criteria under the NCO and EIAO for assessing the airborne noise impacts of blasting and are therefore beyond the scope of the EIA. However, the administrative and procedural control of all blasting operations in Hong Kong is vested in the Mines Division of the Civil Engineering and Development Department (CEDD). The Dangerous Goods (General) Regulations, Chapter 295 also stipulates that no person shall carry out blasting unless he possesses a valid mine blasting certificate to be issued by the Mines Division of CEDD. The Superintendent of Mines will review the application on a case-by-case basis before issuing the Mine Blasting Certificate.

Fixed Plant Noise

3.14 The NCO and IND-TM control noise from fixed noise sources such as ventilation shaft, chiller and cooling tower. For the assessment of impacts from fixed noise sources, the area sensitivity rating (ASR) of the noise sensitive receivers must be determined in accordance with the IND-TM, and based on the ASR, the appropriate acceptable noise levels (ANL) can be determined. ANL is shown in Table 3.2. For this assessment, the ASRs assumed for each NSR and the associated ANL are shown in Appendix 3.1.

Table 3.2 Acceptable Noise Level for Fixed Plant Noise

Time Period	NCO criteria			TM-EIA
	ASR ‘A’	ASR ‘B’	ASR ‘C’	ASR ‘A’	ASR ‘B’	ASR ‘C’
Daytime and Evening (0700-2300 hours)	60	65	70	55	60	65
Night-time (2300-0700 hours)	50	55	60	45	50	55

Source: IND-TM

3.15 In any event, the Area Sensitivity Rating assumed in the EIA Report is only for indicative and it is used for assessment only. It should be noted that the fixed noise sources are controlled under section 13 of the NCO. Therefore, 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/ situations of adjoining land uses. Nothing in the EIA study shall bind the Noise Control Authority in the context of law enforcement against any of the fixed noise sources being assessed.

3.16 More stringent criteria for assessing noise impacts of fixed plant are recommended in the EIAO-TM for planning purposes. The recommended assessment criteria are as follows:

§ Criteria (1) : 5dB(A) below the appropriate Acceptable Noise Levels (ANL) set out in the IND-T

§ Criteria (2) : The prevailing background noise level where the prevailing background noise level is 5dB(A) below the appropriate ANL (i.e. ANL – 5dB(A)).

3.17 Criteria (2) would be more stringent than Criteria (1), and would generally apply to areas with low ambient noise levels such as rural and suburban areas. The Project areas are located in well developed urban areas of Hong Kong Island and as noted from site observations, the prevailing background noise levels would unlikely be 5dB(A) lower than the appropriate ANL (i.e. Daytime 60 or 65dB(A) and Nighttime 50 or 55dB(A)). Thus, Criteria (1) have been adopted assessment criteria for the fixed plant noise impact assessment.

Noise Sensitive Receivers

3.18 Representative NSRs within 300m of the Project boundary were identified for noise assessment.

3.19 According to Annex 13 of the EIAO-TM, NSRs include the following:

§ Residential uses – all domestic premises including temporary housing

§ Institutional uses – including educational institutions

§ Other uses such as hostels and country parks

3.20 In order to evaluate the construction and operational noise impacts likely to arise from the Project, representative NSRs (both existing and planned NSRs) were selected within the study area (i.e. those at the most critical locations) according to the criteria set out in the EIAO-TM, through site visits and a review of relevant land use plans including the Outline Zoning Plan (Plan No. S/H1/14 and S/H3/21).

3.21 NSRs located closest to the subject noise sources, i.e. the first layer of NSR, would be considered as the most critical locations and thus selected for noise assessment. Table 3.3 presents a summary of representative NSRs selected for the present assessment. Locations of representative NSRs are shown in Figure 3.1-3.13.

Table 3.3 Representative Noise Sensitive Receivers

Works Area	NSR	Description	Land Use	Existing / Planned NSR	No of storey	Construction Noise Assessment	Fixed Plant Noise Assessment
KET Station
C & D – Kennedy Town Station Box	KET 1	Kwun Lung Lau (Block D)	Residential	Existing	21	√	√
	KET 2	Luen Fat Apartments	Residential	Existing	15	√
	KET 3	Luen Tak Apartments	Residential	Existing	15	√
	KET 4	Smithfield Terrace (Block D)	Residential	Existing	27	√
	KET 5	Pokfield Garden	Residential	Existing	18	√	√
	KET 6	University Heights (Tower 2)	Residential	Existing	37	√	√
	KET 7	Kam Po Mansion	Residential	Existing	5	√
	KET P1	Kwun Lung Lau	Residential	Planned	-	√	√
A – Ex-Police Quarter	KET 9	Hong Kong Institute of Vocation Education (Tsing Yi) Kennedy Town Centre	School	Existing	7	√	√
B – Abattoir Site	KET 10	Lui Ming Cho Primary School	School	Existing	7	√
	KET 11	Cayman Rise (Block 1)	Residential	Existing	31	√
	KET 12	Cheong Kat Building	Residential	Existing	22	√
	KET 13	The Merton (Block 2)	Residential	Existing	45	√
	KET 14	Kennedy Town Jockey Club Clinic (A/C)	Clinic	Existing	3	√
MA – Under-ground Magazine Site	KET 15	Sisters of the Immaculate Heart of Mary (Kongmoon) – Kit Sam Convent	Residential	Existing	2	√
UNI Station
J2 - Entrance B1	UNI 1	Western Court (Block 1)	Residential	Existing	10	√
	UNI 2	St. Louis School	School	Existing	5	√
H - Entrance C2	UNI 3	Sun Court	Residential	Existing	23	√
	UNI 4	The Belcher's (Tower 8)	Residential	Existing	45	√
	UNI 5	Po Leung Kuk Chan Au Big Yan Home for the Elderly	Residential	Existing	3	√
	UNI 6	Sun Shing Building	Residential	Existing	21	√
J3 - Entrance A	UNI 7	The Bauhinia	Residential	Existing	9	√
	UNI 8	Hong Kong Chiu Sheung School	School	Existing	4	√
I - Entrance C1, VS-Z & chiller	UNI 9	The Belcher's (Tower 3)	Residential	Existing	45	√	√
	UNI 10	St. Paul's College Primary School	School	Existing	7	√
J -Entrance B2, and J1 - Vent Shaft VS-Y	UNI 11	Sik On Building	Residential	Existing	9	√	√
	UNI 12	Hill Court	Residential	Existing	23	√
	UNI 13	Graceful Court	Residential	Existing	24	√
	UNI 13a	Fu Yin Court	Residential	Existing	22		√
	UNI 14	Wing Fu Lau	Residential	Existing	5	√	√
G - UNI Construct-ion Shaft	UNI 15	Yick Fung Garden (Block A)	Residential	Existing	30	√
	UNI 16	Sunglow Building	Residential	Existing	24	√
I - Entrance C1, VS-Z & chiller	UNI 17	Hillview Garden (Blocks 1-4)	Residential	Existing	6		√
	UNI 17a	Hillview Garden (Blocks 5-8)	Residential	Existing	6		√
E & F - PCWA Barging Point	UNI 18	Wah Po Building	Residential	Existing	24	√
	UNI 19	Jade Court (Block A)	Residential	Existing	25	√
SYP Station
N1 - Entrance A1 & A2	SYP 1	No. 18-20 Eastern Street	Residential	Existing	5	√
	SYP 2	No. 28 Sai Woo Lane	Residential	Existing	5	√
	SYP 3	No. 15 Tsz Mi Alley	Residential	Existing	5	√	√
	SYP 4	Ngan Yu Building	Residential	Existing	6	√	√
	SYP 5	Rich Court	Residential	Existing	21	√	√
	SYP 16	Wai Lee Building	Residential	Existing	9	√	√
M3 -Entrance C	SYP 6	Bon-Point	Residential	Existing	32	√	√
	SYP 7	Bonham Road Government Primary School	School	Existing	2	√	√
M1 -Entrance B1 & B2	SYP 8	Ivy Tower	Residential	Existing	29	√
	SYP 9	Yee Shun Mansion	Residential	Existing	19	√
	SYP 10	Chun King Court	Residential	Existing	25	√
L1 - Entrance B3	SYP 11	Kiu Shing Building	Residential	Existing	8	√
	SYP 12	No. 9-11 Ki Ling Lane	Residential	Existing	4	√
	SYP 13	No. 9-15 Sai Yuen Lane	Residential	Existing	5	√
M - KGV Construct-ion Shaft	SYP 14	No. 1 Third Street	Residential	Existing	29	√
	SYP 15	H.K.S.P.C Thomas Tam Day Nursery (A/C)	Nursery	Existing	1	√
O1 – Ground Treatment	GT 1	Overseas Trust Bank Building	Residential	Existing	8	√
	GT 2	Princeton Tower	Residential	Existing	40	√
O2 – Ground Treatment	GT 3	Talon Tower	Residential	Existing	22	√
	GT 4	Yu Hing Mansion	Residential	Existing	15	√
O3 – Ground Treatment	GT 5	Ka On Building	Residential	Existing	18	√
	GT 6	Hongway Garden	Residential	Existing	35	√

3.22 It should be noted that some works areas would be designated for material storage and site facilities only, and the use of PME was not anticipated at these works areas. Therefore, no construction noise assessment would be needed for these works areas. These works areas include works area K at Mui Fong Street, works area L at Mui Fong Street Children’s Playground, and works area M2 at David Lane (Figures 2.19-2.25 refer).

Description of the Environment

3.23 The proposed WIL is an extension of the Island line from Kennedy Town to Sheung Wan via Sai Ying Pun and University. The Project Site is located on the western side of Hong Kong Island. The surrounding land uses mainly comprise a mixture of commercial and residential uses.

3.24 Site visits conducted from November 2005 to August 2006 revealed that NSRs identified within the Study Area were exposed to noise from the traffic along existing road networks including Victoria Road, Forbes Street, Pok Fu Lam Road, Praya Kennedy Town, Queen Road West and Bonham Road. Key sources of noise impact to the existing NSRs are summarised in the Table 3.4.

Table 3.4 Key Noise Sources to the Existing NSRs

Location	Existing Noise Sources affecting NSR
NSRs near KET	Traffic noise from Victoria Road and Forbes Street
NSRs near UNI	Traffic noise from Pok Fu Lam Road and Praya Kennedy Town
NSRs near SYP	Traffic noise from Queen’s Road West and Bonham Road

Assessment Methodology

Construction Noise

3.25 In accordance with the EIAO-TM, the methodology outlined in the GW-TM was used for the construction noise assessment. 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 Powered Mechanical Equipment (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

§ Include a 3 dB(A) façade correction to the predicted noise levels in order to account for the façade effect at each NSR.

3.26 Sound power levels (SWLs) of the equipment were taken from Table 3 of GW-TM. Where no sound power level (SWL) was given in the GW-TM, reference was made to British Standard 5228:Part 1:1997 Noise Control on Construction and Open Sites and previous similar studies or from measurements taken at other sites in Hong Kong. Groups of PME were assigned for various construction activities of the proposed Project. The proposed plant inventory for the construction of the Project is presented in Appendix 3.2. The Engineering Consultant of the Project Proponent has confirmed the proposed plant inventory as being practical and adequate for completing the works within the scheduled timeframe. The plant inventory has been provided as one option which is considered technically feasible, and would represent a realistic worst case scenario for assessment purposes. In detail design stage, the Contractor may propose alternative plant schedule should it be considered necessary and appropriate. However, the alternative plant inventory should be reviewed and verified by the Environmental Team and Independent Environmental Checker respectively.

Operational Phase – Fixed Noise Sources

Assumed Fixed Plant Inventory

3.27 According to the design information, the major fixed plant noise sources identified include ventilation shafts, chillers and cooling towers. Other building services equipment such as transformer, pump and emergency generator will be placed inside plant rooms which are expected to be fully enclosed. A summary of the identified fixed plant noise sources to be operated are summarised in Table 3.5.

Table 3.5 Summary of Fixed Plant Noise Sources for the proposed WIL

Location	Fixed Noise Sources	ID	Number of Fixed Plant
KET Station	Ventilation Shaft	VS-Y, VS-Z	2 units
	Chiller Plant	CP 1-3	3 units
KET Station – Ex-police Quarters	Ventilation Shaft	KET-VS	1 unit
UNI Station - Entrance C1	Ventilation Shaft	VS-Z1, VS-Z2, VS-Z3	3 units
	Chiller Plant	CP 1-3	3 units
UNI Station – Vent Shaft Y	Ventilation Shaft	VS-Y	1 unit
SYP Station-Entrance A1 & A2	Ventilation Shaft	VS-Y	1 unit
SYP Station- Entrance C	Ventilation Shaft	VS-Z	1 unit
	Chiller Plant	CP 1-3	3 units

3.28 It was assumed in the assessment that chiller plants would be installed to provide cooling for the three stations. It was assumed that, for each station there would be 3 chiller units evenly distributed in the areas designated for their provision. Indicative locations of the chiller units are depicted in Figures 3.9, 3.10 and 3.13.

Assessment Methodology and Assumptions

3.29 In the absence of any detailed information and noise specification of the proposed fixed plant, the maximum permissible noise emission levels were determined for future detailed design of the fixed plant.

3.30 For the assessment of noise from the fixed plant, the maximum permissible sound power levels (Max SWLs) of the identified fixed noise sources were determined by adopting standard acoustics principles. The following formula was used for calculating the Max SWLs of the fixed plant.

SPL = Max SWL – DC + FC - BC

where

Sound Pressure Level, SPL in dB(A)

Maximum Permissible Sound Power Level, Max SWL in dB(A)

Distance Attenuation, DC in dB(A) = 20 log D + 8 [where D is the distance in metres]

Façade Correction, FC in dB(A) = 3 dB(A)

Barrier Correction, BC in dB(A)

3.31 It is assumed that all the fixed plant within the same location would be operated at the same time as worst case scenario. Screening correction offered by buildings or other structures such as office and residential building were taken into account in calculating the predicted noise levels. According to the GW-TM, effective barriers can result in noise reduction of 5-10dB(A) for the fixed plant depending on the line of sight of the representative NSRs. A positive 3 dB(A) was added to predicted noise levels at the NSRs due to the façade effect.

3.32 No corrections have been applied for tonality, intermittency or impulsiveness. If the noise exhibits any of these characteristics during the operation of the plant, the noise limit should be reduced in accordance with the recommendation given in Section 3.3 of IND-TM.

Identification of Environmental Impact

Construction Phase

3.33 The potential source of noise impact during the construction phase of the Project would mainly be the use of PME for various construction activities. As broadly indicated in the construction program (Appendix 2.2 refers), the construction of the Project would be from early 2009 to end 2013 / early 2014.

3.34 The length of the proposed WIL is approximately 3 km. Three new underground stations will be provided, namely KET, UNI and SYP. Key WIL elements involving construction activities to be carried out at surface would include: (1) entrance structures/lift entrances (2) ventilation shafts (3) entrance adits, (4) a cut-and-cover box at KET Station and (5) temporary magazine site.

3.35 Since the Western District is a highly developed area, demolition of some existing buildings would be necessary to create space for WIL facilities. Demolition of buildings could however have a potential to generate high construction noise levels. The buildings to be demolished and the proposed usage of WIL at the cleared site are summarised in the table below.

Table 3.6 Existing Buildings to be Demolished

Existing Buildings to be Demolished	Proposed Use
Blocks A and C, Ex-police Quarter at Kennedy Town	Construction shaft and vent shaft (KET-VS)
Kennedy Town Swimming Pool	KET Station and associated Entrances A and B
Whitty Street Public Toilet	UNI Entrance B1
Centre Street Market & Centre Street Cooked Food Centre	SYP Entrances B1 and B2
Hong Kong Government David Trench Rehabilitation Centre	SYP Entrance C
Tai Shing House, and Nos. 2 & 4 Tsz Mei Alley	SYP Entrance A1

3.36 There would be four tunnel construction shafts through which excavated spoil from tunneling would be mucked out. These shafts could have higher potential of airborne construction noise. The four tunnel construction shafts would be:

· Works Area A (Ex-police Quarter) – working shaft for construction of the overrun tunnels and installation of rails

· Works Area G (Kennedy Praya) – The excavated materials from the construction of tunnels between the east of KET Station and west of SYP Station, and the UNI and SYP Stations with their associated adits are disposed via the PCWA barging point. Most of this excavated volume will reach ground level via the construction shaft at Works Area G in the Kennedy Praya site, and then be transported by a conveyor system across Shing Sai Road and along the edge of the PCWA access road to the barging point, as shown in Figure 11.5.

· Works Area J (Hill Road Rest Garden) – working shaft for the construction of running tunnels between east of UNI and west of SYP Stations.

· Works Area N1 (Sai Woo Lane) – working shaft for the construction of running tunnels between east of SYP and west of SHW Stations. It would also be a possible TBM launching shaft. No retrieval shaft would be needed as the machine will be left in the ground.

3.37 There would be another construction shaft proposed at the existing King George V Memorial Park. The shaft would be constructed at the Basketball Court of the park. Different from the other four construction shafts mentioned above, this shaft would not be used for mucking out but for personnel and material access only.

3.38 There would be two barging points for transporting of spoil generated from the construction of WIL to designated public fill reception facilities at Tuen Mun and / or Tseung Kwan O. These two barging points would be located at Works Area B at KET Abattoir Site and Works Area E at the Western PCWA. Rock crushers would be installed at the barging points to support their operation. Possible locations of the proposed rock crushers are shown in Figures 11.4 and 11.5.

3.39 Summarised in Table 3.7 below are key construction activities at various works areas which would result in elevated construction noise levels, as well as the PME which were identified as the dominant source of noise impact. Locations of various construction activities and works areas are shown in Figures 2.19 - 2.25.

Table 3.7 Summary of Key Construction Works along the WIL

Location	Works Area	Major Noisy Construction Activities	PME Identified as the Major Source of Noise Impact
KET Station
Underground Magazine	MA	Possession of Site	Drill Rig (SWL=110 dB(A))
		Construction of Magazine	Drill Rig (SWL=110dB(A)) Jumbo Drill Rig (SWL=110dB(A))
Ex-Police Quarter	A	Demolition (Kennedy Town Ex-Police Quarters, Block A & C)	Hydraulic Breaker (SWL= 110 dB(A))
		Pilling/walling	Pile rig (SWL = 112 dB(A))
Abattoir Site	B	Rock Crusher Operation	Crusher (SWL= 118 dB(A))
KET Station	C	Piling/walling	Pilling, earth auger (SWL= 114 dB(A))
		Excavate rock and base	Rock Drill (SWL= 123 dB(A))
		Commence KET Turnback Tunnel	Drill Rig (SWL= 110 dB(A))
	D	Demolish Pools and Grandstand	Hydraulic Breaker (SWL= 110 dB(A))
		Piling/walling	Pilling, earth auger (SWL= 114 dB(A))
		Excavate rock and base	Rock Drill (SWL= 123 dB(A))
		Commence KET to SYP Tunnel	Drill Rig (SWL= 110 dB(A))
UNI Station
UNI Entrance B1	J2	Demolition of Whitty Public Toilet Block	Concrete Corer (SWL= 117 dB(A))
		Piling/ Walling	Pile Rig (SWL= 112 dB(A))
		Excavation – Soft	Drill Rig (SWL= 110 dB(A))
		Excavation – Weak Rock	Drill Rig (SWL= 110 dB(A))
		Excavation - Rock	Rock Drill (SWL =123 dB(A))
UNI Entrance B2	J	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Excavation - Rock	Rock Drill (SWL= 123 dB(A))
		Excavate adit and running tunnel	Rock Drill (SWL= 123 dB(A))
UNI Entrance C2	H	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Excavate Rock	Rock Drill (SWL= 123 dB(A))
UNI Entrance C1	I	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Reinstatement	Pile Extractor (SWL= 125 dB(A))
UNI Entrance A	J3	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Horizontal Adit	Crawler mounted rock drill trucks (SWL= 123 dB(A))
UNI Vent Shaft VS Y	J1	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Excavation – Weak Rock	Rock Drill (SWL= 123 dB(A))
		Horizontal Adit	Crawler mounted rock drill trucks (SWL= 123dB(A))
UNI Construction Shaft (at Kennedy Town Praya)	G	Piling / Walling	Pile Rig (SWL= 112 dB(A))
		Excavation - Rock (Horizontal Adit)	Rock Drill (SWL= 123 dB(A))
PCWA Barging Point	E & F	Possession of Site	Concrete Saw (SWL = 115 dB(A))
		Construction	Concrete Poker (SWL = 113 dB(A))
		Rock Crusher Operation	Crusher (SWL = 118 dB(A))
SYP Station
SYP Entrance A1 & A2	N1	Demolition of Existing Building (No.2-4 Tse Mi Alley & Tai Shing House)	Hydraulic Breaker (SWL= 110 dB(A))
		Install sheet piles and bored piles at playground	Pile Rig (SWL= 112 dB(A))
		Install bored piles and H-piles for shaft	Pile Rig (SWL= 112 dB(A))
		Excavate to tunnel level	Rock Drill (SWL= 123 dB(A))
SYP Entrance B1 & B2	M1	Demolition of Existing Building (Centre Street Market West Block)	Concrete Corer (SWL= 117 dB(A))
		Piling/Walling	Piling, auger (SWL= 114 dB(A))
		Excavate Rock	Rock Drill (SWL= 123 dB(A))
SYP Entrance B3	L1	Piling/Walling	Piling, auger (SWL= 114 dB(A))
		Installation of Pipe Pile for Soft Ground Tunnel	Piling, auger (SWL= 114 dB(A))
SYP Entrance C	M3	Demolition of Existing Building (David Trench Rehabilitation Centre)	Hydraulic Breaker (SWL= 110 dB(A))
		Piling/Walling	Piling, auger (SWL= 114 dB(A))
		Excavate Rock	Rock Drill (SWL= 123 dB(A))
		Excavate Rock Adit (Hard Rock Excavation)	Crawler mounted rock drill trucks (SWL = 123dB(A))
KGV Construction Shaft	M	Piling/Walling	Piling, auger (SWL= 114 dB(A))
		Excavate Rock	Rock Drill (SWL= 123 dB(A))
Ground Treatment Works	-	Ground Treatment	Drill Rig (SWL= 110 dB(A))

3.40 The use of PME for the above construction activities would be the main source of construction noise impact. As NSRs in the vicinity to the works areas were identified, noise control measures would likely be necessary to ensure that construction noise impact at the identified NSRs would be within acceptable levels.

3.41 Based on the current design, two ventilation fans would be installed inside the magazine adit and operated for 24 hours to provide ventilation to the magazine. Therefore, assessment of construction noise during restricted hours, which is controlled under section 6 of the NCO, would be carried out in this EIA report to evaluate the feasibility of construction work during restricted hours. It should be noted that, however, regardless of the assessment results, the Noise Control Authority under the NCO will consider an application based on the relevant technical memoranda issued under the NCO, the contemporary condition/situations of adjoining land uses and any previous complaints against construction activities at the site. The assessment carried out in this EIA report is indicative only and is meant to demonstrate that practical and feasible approaches could be found.

3.42 The construction of the Project would induce additional traffic to the existing traffic network. Based on the preliminary construction programme, it is envisaged that only about 5 construction vehicles per hour (on average) would be induced by the proposed Project. No insurmountable noise impact due to project-induced traffic during construction phase would be expected.

3.43 The tunnel section of the proposed alignment will largely be excavated by drill and blast method. According to the design information, there will be not more than 2 blasts per day per work front for tunnel construction: one blast in the morning and one in the early evening. Each blast would last for only a few seconds. Multiple, underground blasts on different work fronts will be carried out within a single area, spread over five to ten minutes. The blasting as well as the removal of debris and rocks after blasting would be carried out during non-restricted hours. The broken rock would be removed by conveyor belt to a barging point at Western PCWA Site.

3.44 As mentioned in Section 3.13, blasting is under the control of the Dangerous Goods Ordinance. Therefore, the contractor shall obtain a blasting permit from the Mines Division of CEDD before carrying out the blasting. The Contractor shall enclose a method statement including manner of working and protective measures to protect adjacent land and property when blasting is carried out.

Operation Phase

Fixed Plant Noise

3.45 Noise from fixed plant associated with an underground railway would mainly be associated with tunnel ventilation (e.g. tunnel vent shafts) and cooling systems for stations (e.g. cooling towers and chillers). Locations of the identified fixed plant for WIL are shown in Figure 3.8-3.13.

Evaluation of Impacts

Construction Phase

3.46 As broadly illustrated in the construction programme, various construction activities for WIL may be carried out concurrently during a particular period. The unmitigated cumulative noise levels at representative NSRs were predicted. Table 3.8 presents the unmitigated construction noise levels predicted at representative NSRs.

Table 3.8 Unmitigated Construction Noise Levels during Non-restricted Hours

NSR ID	Description	Predicted Unmitigated Construction Noise Levels, dB(A)			EIAO-TM Noise Criteria, dB(A)
KET 1	Kwun Lung Lau (Block 2)	72	-	91	75
KET 2	Luen Fat Apartments	73	-	90	75
KET 3	Luen Tak Apartments	71	-	91	75
KET 4	Smithfield Terrace (Block D)	67	-	90	75
KET 5	Pokfield Garden	62	-	89	75
KET 6	University Heights (Tower 2)	60	-	85	75
KET 7	Kam Po Mansion	61	-	88	75
KET 9	Hong Kong Institute of Vocation Education (Tsing Yi) Kennedy Town Centre	43	-	89	65/70^(1)
KET 10	LMC Primary School	61	-	80	65/70^(1)
KET 11	Cayman Rise (Block 1)	63	-	79	75
KET 12	Cheong Kat Building	41	-	75	75
KET 13	The Merton (Block 2)	40	-	77	75
KET 14	Kennedy Town Jockey Club Clinic (A/C)	63	-	83	75
KET 15	Sisters of the Immaculate Heart of Mary (Kongmoon) – Kit Sam Convent	77	-	84	75
KET P1	Kwun Lung Lau	69	-	87	75
UNI 1	Western Court (Block 1)	42	-	83	75
UNI 2	St. Louis School	42	-	82	65/70^(1)
UNI 3	Sun Court	43	-	91	75
UNI 4	The Belcher's (Tower 8)	44	-	87	75
UNI 5	PLK Chan Au Big Yan Home for the Elderly	44	-	94	75
UNI 6	Sun Shing Building	43	-	89	75
UNI 7	The Bauhinia	46	-	90	75
UNI 8	Hong Kong Chiu Sheung School	46	-	84	65/70^(1)
UNI 9	The Belcher's (Tower 3)	49	-	84	75
UNI 10	St. Paul's College Primary School	46	-	85	65/70^(1)
UNI 11	Sik On Building	47	-	95	75
UNI 12	Hill Court	45	-	91	75
UNI 13	Graceful Court	46	-	90	75
UNI 14	Wing Fu Lau	48	-	85	75
UNI 15	Yick Fung Garden (Block A)	42	-	87	75
UNI 16	Sunglow Building	42	-	88	75
UNI 18	Wah Po Building	43		83	75
UNI 19	Jade Court (Block A)	41		76	75
SYP 1	No. 18-20 Eastern St	62	-	96	75
SYP 2	No. 28 Sai Woo Lane	61	-	94	75
SYP 3	No. 15 Tsz Mi Alley	66	-	93	75
SYP 4	Ngan Yu Building	78	-	95	75
SYP 5	Rich Court	62	-	94	75
SYP 6	Bon-Point	81	-	95	75
SYP 7	Bonham Road Government Primary School	42	-	92	65/70^(1)
SYP 8	Ivy Tower	42	-	91	75
SYP 9	Yee Shun Mansion	43	-	97	75
SYP 10	Chun King Court	43	-	90	75
SYP 11	Kiu Shing Building	43	-	93	75
SYP 12	No. 9-11 Ki Ling Lane	43	-	94	75
SYP 13	No. 9-15 Sai Yuen Lane	43	-	97	75
SYP 14	No. 1 Third Street	43		98	75
SYP 15	H.K.S.P.C Thomas Tam Day Nursery (A/C)	45		87	65/70^(1)
SYP 16	Wai Lee Building	45	-	85	75
GT 1	Overseas Trust Bank Building	41	-	87	75
GT 2	Princeton Tower	43	-	87	75
GT 3	Talon Tower	40	-	82	75
GT 4	Yu Hing Mansion	40	-	81	75
GT 5	Ka On Building	44	-	91	75
GT 6	Hongway Garden	44	-	91	75

Note: (1) EIAO-TM noise limits of L_{eq(30 min)} 70dB(A) for schools during normal hours (65dB(A) during examination periods)

3.47 The construction noise impact assessment during non-restricted hours showed that predicted cumulative noise levels at the representative NSRs would range from 40 to 98 dB(A) which would exceed the EIAO-TM noise criteria by up to 23dB(A).

3.48 As mentioned in Section 3.41, two ventilation fans would operate for 24 hours during operation of the magazine. Preliminary construction noise impact assessment during restricted hours as defined under NCO has been carried out, and the results showed that predicted noise levels at KET 15 during restricted hours would be 59 dB(A), exceeding the NCO criteria by 14dB(A).

3.49 Mitigation measures are considered necessary in order to abate the construction noise impacts at all works areas. Appendix 3.2 shows the detailed construction noise calculations for the unmitigated scenario.

Operation Phase

3.50 Max SWLs would be determined by following the methodology as described in Section 3.30-3.33. Potentially worst affected NSRs were selected for the assessment and their corresponding Max SWLs were determined in accordance with IND-TM and the EIAO-TM. Appendix 3.3 presents the details of noise assessment for the proposed fixed plant using both daytime and night time noise criteria. Table 3.9 presents a summary of the required Max SWLs for key fixed plant along the WIL alignment.

Table 3.9 Maximum Sound Power Level (SWL) for Key Fixed Plant

Source ID	Description		Direction Facing	Maximum SWL at daytime, dB(A)	Maximum SWL at nighttime, dB(A)
KET Station
VS-Y	Ventilation Shaft	TVS	North	90	80
			West	90	80
		TVS	East	90	80
		BEVS	South	90	80
		SEVS	North	90	80
		SSVS	South	90	80
		TSVS	East	86	76
		TEVS	South	85	75
VS-Z	Ventilation Shaft	BEVS	North	95	85
			East	85	75
			South	85	75
		TEVS	North	94	84
		TSVS	South	85	75
		SSVS	South	85	75
		TVS	North	92	82
		TVS	South	85	75
			West	92	82
CP	Chiller Plant	1	-	91	81
		2	-	91	81
		3	-	91	81
KET Ex-police Quarter
KET VS	Ventilation Shaft	-	Northwest	106	-
		-	Southeast	105	-
UNI Station (Entrance C1)
VS-Z1	Ventilation Shaft	BEVS	North	91	81
			East	92	82
			South	96	86
		TVS	West	92	82
VS-Z2	Ventilation Shaft	TVS	North	94	84
			East	94	84
			South	98	88
VS-Z3 & CP	Ventilation Shaft and Chiller Plant	1	-	94	84
		2	-	94	84
		3	-	94	84
UNI Station (Under Hill Road Flyover)
VS-Y	Ventilation Shaft	SSVS	North	83	73
			South	80	70
			West	80	70
		TVS	North	82	72
		TEVS	South	83	73
SYP Station (Entrance A1 & A2)
VS-Y	Ventilation Shaft	TVS	South	87	77
			West	87	77
SYP Station (Entrance C)
VS-Z	Ventilation Shaft	SSVS	North	75	65
			South	75	65
			West	76	66
		SEVS	North	80	70
		BEVS	North	81	71
			East	84	74
		TVS	East	84	74
			South	83	73
		TEVS	South	82	72
			West	78	68
CP	Chiller Plant	1	-	80	70
		2	-	80	70
		3	-	80	70

3.51 It should be noted that the calculation of the maximum SWLs is based on the worst-case scenario including the emergency testing mode. Provided the fixed plants are designed to meet the Max SWLs as indicated in Table 3.9, no adverse noise impacts on the NSRs would be expected.

Mitigation of Adverse Environmental Impacts

Construction Phase

3.52 Due to the extensively developed and densely populated nature of the Western Hong Kong Island, it is unavoidable that construction of such a large-scale railway network would cause noise impacts to the surrounding residences, especially during construction phase of the Project. To strike a balance between the need for providing a railway system to locals and the public concerns on the adverse impacts, the following key features have been considered during the design of the Project to alleviate the construction noise impacts as far as practicable:

§ Minimise the number of PME.

§ Works would be implemented in phases, where possible, in order to reduce the number of PME required to be on-site.

3.53 It is proposed to excavate a tunnel more than 300m long from a shaft on a vacant site on Kennedy Town Praya to UNI station. Spoil from the excavation of UNI and SYP station caverns and most of KET to UNI running tunnels will be removed through this tunnel. By adopting this approach for spoil removal, construction noise impacts can be reduced as the shaft at which mucking out activities would take place would be located relatively distant from NSRs.

3.54 The construction noise assessment showed that, in the absence of any mitigation measures, there would be exceedance of the construction noise criteria at some of the NSRs. Various mitigation options have thus been considered in accordance with the guidelines laid down in the Environmental Impact Assessment Ordinance, Guidance Note No. 9/2004 “Preparation of Construction Noise Impact Assessment under the Environmental Impact Assessment Ordinance” (GN 9/2004). It should be noted that the assumptions used in formulating mitigation measures and their practicality were based on the best available information from the preliminary design stage of the Project. Alternative mitigation proposals which could achieve the same noise reduction effect may be formulated in detailed design stage. Mitigation measures considered are discussed below.

Good Site Practice

3.55 Although the noise mitigation effects are 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 each phase of construction:

§ Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program

§ Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program

§ Mobile plant, if any, should be sited as far 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 so that the noise is directed away from the nearby NSRs

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

Adoption of Quieter PME

3.56 In order to reduce the excessive noise impacts at the affected NSRs during normal daytime working hours, quieter PME are recommended. The Contractors do not have to use specific items of quiet plant adopted in this assessment. The Contractors may use other type of quiet plant, which have the same total SWL, to meet their needs. The quiet PME adopted in the assessment were taken from the BS5228: Part 1:1997 (Appendix 3.4). It should be noted that the silenced PME selected for assessment can be found in Hong Kong.

3.57 A list of quieter PME recommended for adoption during the construction phase is presented in Table 3.10.

Table 3.10 Quieter PME Recommended for Adoption during Construction Phase

PME	Power rating/size, weight	Reference	SWL
Dump Truck	450kW, 50t	BS C9/39	103
Tracked Crane	62kW	BS C7/114	101
Tracked Excavator/Loader	52kW	BS C3/97	105
Wheeled excavator/loader fitted with hydraulic rock breaker	52kW	BS C8/12	106
Truck Mixer	22kW, 6m^3	BS C6/23	100
Poker Vibrators	0.75 each poker	BS C6/40	98
Electrical Vibratory Extractor	24 Hz	BS C4/22	125
Road Roller	51kW	BS C8/30	101
Asphalt Spreader	90kW, 13t	BS C8/24	101
Tracked Excavator Fitted with Hydraulic Breaker	200kg	BS C8/13	110
Consolidated rig (down-the-hole hammer)	160kW	BS C11/2	112
Tracked Crane	58kW, 34t	BS C7/112	102
Sheet Steel Piling, Hydraulic	220 000 kg/pile	BS C4/13	106

Use of Movable Noise Barrier

3.58 The use of movable barrier for certain PME could further alleviate the construction noise impacts. In general, 5dB(A) reduction for movable PME and 10dB(A) for stationary PME can be achieved depending on the actual design of movable noise barrier.

3.59 Table 3.11 shows the assumed noise reduction effects achieved by the movable noise barrier for certain items of PME. The Contractor shall be responsible for design of the movable noise barrier with due consideration given to the size of the PME and the requirement of intercepting the line of sight between the NSRs and PME. Barrier material of surface mass in excess of 7 kg/m² is recommended to achieve the predicted screening effect.

Use of Noise Enclosure/Acoustic Shed

3.60 Noise enclosure would be used to cover stationary PME such as air compressor and concrete pump. With the adoption of the noise enclosure, the PME could be completely screened, and noise reduction of 15 dB(A) could be achieved with reference to Paragraph 4.5 of EIAO Guidance Note No. 9/2004.

Use of Acoustic Enclosure

3.61 Enclosing a rock drill in a portable or fixed acoustic enclosure with suitable ventilation would result in up to 20dB(A) noise reduction (Table B1 of BS5228 refers). The acoustic enclosure should enclose the PME as fully as possible. It should possess adequate insulation so that noise energy would not readily pass through them. A sheet material mass of 10kg/m² should be used to give this insulation. It should be lined inside with an efficient sound absorbent so that noise would not be built up within them or reflected out through openings. The sound-absorbent lining inside the enclosure should normally be at least 25mm thick.

Use of Noise Insulating Cover (NIC)

3.62 The noise insulating cover (NIC) would be used to cover some of the mucking out points where necessary and practical. It was reported in the EIA Report for the Kowloon Southern Link project that the NIC could achieve an overall noise reduction of 22dB(A). Typical configuration of acoustic panels that could achieve this insulation requirement would be 1.5 GS outer skin, 100mm acoustic infill (e.g. fiber glass) with 80kg/m³, and an inner perforated sheet (refer to Figure 3.25). As a more conservative approach, a noise reduction of 20dB(A) was assumed in this calculation.

Use of Silencer

3.63 To reduce noise emission from the ventilation fans, silencers are also recommended to be used in fan ventilation system to attenuate noise generated during fan operation to achieve a noise reduction of 15dB(A). The Contractor shall be responsible for selection of appropriate silencers for the ventilation fans.

Use of Noise Insulating Fabric

3.64 Noise insulating fabric (the Fabric) would be adopted for certain PME (e.g. drill rig, piling auger etc). The Fabric should be lapped such that there would be no opening or gaps on the joints. With reference to MTRC Contract C4420 Tsim Sha Tsui Modification Noise Assessment Report for Variation of Environmental Permit (July 2003) and the technical data from manufacturer, a noise reduction of over 10 dB(A) could be achieved with the use of the Fabric. As a conservative approach, a noise reduction of 10 dB(A) for the PME lapped with the Fabric was assumed in this assessment.

3.65 The Fabric would also be used for screening the noise emitted from the use of PME for the demolition works at the Kennedy Town Ex-police Quarter Block A & C. Prior to the commencement of demolition works at this location, steel scaffolds would be erected. The Fabric would be mounted on the scaffolds to an extent such that the line of sight between the noise source i.e. breakers and NSR (NSR KET9 i.e. Hong Kong Institute of Vocation Education (Tsing Yi) Kennedy Town Centre) would be blocked (the whole set up is hereinafter referred to as “the Noise Control Curtain”). The Noise Control Curtain should be installed without any gaps on the joints, and the sound-absorptive side of which would face the noise source to be shielded. The material of the Fabric to be used for the Noise Control Curtain would be the same as that mentioned in Section 3.63 above to achieve noise reduction. The proposed extent of the Noise Control Curtain is depicted in Figure 3.21. A noise reduction of 5dB(A) was assumed for this mitigation measure.

3.66 A summary of the assumed noise reduction effects achieved by the use of movable noise barrier, noise enclosure, silencer, acoustic enclosure, the Fabric as well as the Noise Control Curtain for certain item of PME is presented in Table 3.11.

Table 3.11 Noise Mitigation Measures for Certain PME during Construction Phase

PME	Mitigation Measures Proposed	Noise Reduction, dB(A)
Air Compressor	Enclosure/Shed	15
Breaker	Movable Noise Barrier	10
Mini backhoe	Movable Noise Barrier	5
Pile Rig	The Fabric	10
Generator, super silenced	Movable Noise Barrier	10
Backhoe	Movable Noise Barrier	5
Ventilation fan	Silencer	15
Crane	Movable Noise Barrier	5
Rock Drill	Acoustic Enclosure	20
Concrete pump	Enclosure/Shed	15
Poker, vibratory, hand-held	Movable Noise Barrier	10
Pile Extractor	The Fabric	10
Power Rammer	The Fabric	10
Pilling, earth auger	The Fabric	10
Hydraulic Breaker	Movable Noise Barrier	5
Compressor	Enclosure/Shed	15
Wheel Loader	Movable Noise Barrier	5
Crusher	Movable Noise Barrier	5
Concrete Pump	Enclosure/Shed	15
Shotcrete Pump	Enclosure/Shed	15
Grout Pump	Enclosure/Shed	15
Concrete Corer	Enclosure/Shed	15
Grout Plant	Movable Barrier	10
Grout Mixer	Movable Barrier	5
Excavator	Movable Barrier	5
Lorry Crane	Movable Barrier	5
Crawler Crane	Movable Barrier	5
Piling Hydraulic	The Fabric	10
Sheet Piling Machine	The Fabric	10
Rock Drill	Acoustic Enclosure	20
Air compressor, Hand-held breaker & Hydraulic breaker (used for the demolition works at the Ex-police Quarter site)	Noise Control Curtain	5

Use of Temporary Noise Barrier

3.67 The use of temporary noise barriers would be an effective mean to alleviate the noise impact arising from the construction works, particularly at NSRs at lower levels. Site surveys revealed that NSRs located within the Assessment Area would mainly be mid/high-rise in nature (about 10-40 storeys). Having considered the engineering constraints, nature of construction work, height and location of NSRs, the practical heights of the temporary noise barrier have been determined to screen their sensitive façade from viewing the ground-level construction equipment within the site.

3.68 The practicality of using temporary noise barriers would also depend on whether there would be sufficient space available. Hence the use of temporary noise barrier would not be practicable for all areas. In particular, temporary noise barriers would not be suitable for erecting along a lane closure in highway as the barrier might be knocked down by vehicles.

3.69 Having taken into account all the factors mentioned above, temporary barriers would be proposed at the works area C, i.e. the Forbes Street site at KET. Vertical temporary barriers of about 8m and 5m high would be erected along the southern and northern side of the works area respectively at the site boundary, and these temporary barriers would be considered practical. Note that the proposed temporary noise barriers cannot be extended across Smithfield Road as traffic would be needed to be maintained. For those NSRs which could be effectively screened by the proposed temporary noise barriers, a 5 or 10dB(A) noise reduction was assumed depending on the degree of mobility of the PMEs. NSR KET1 and KET3 would be screened by the proposed temporary barrier.

3.70 At SYP Entrance A1 and A2 (Sai Woo Lane), temporary noise barriers were also proposed for screening of noise from the water cooling towers during tunnel construction. The barriers proposed would be about 4.5m to 5m high and erected on the concrete slab. A noise reduction of 10 dB(A) was assumed in the assessment as the water cooling towers would be completely screened by the proposed temporary barriers when viewed from the affected NSR SYP4 and SYP16. The proposed extent of the temporary noise barriers at the two sites is shown in Figures 3.17-3.18.

Decking over the excavation area

3.71 A deck over would be provided to cover the excavation area at the Works Area J – UNI Entrance B2, J3 – UNI Entrance A, G – UNI Construction Shaft and L1 - SYP Entrance B3. The typical configuration of the deck is shown in Figures 3.24. The deck would fully covered the opening of the excavation area / shaft such that noise would not be leaked out from the shaft or tunnel. The inside of the deck cover should be lined with sound-absorbent materials so that a noise reduction of 20dB(A) can be achieved.

Full Enclosure of Works Areas

3.72 It is proposed that works area J2 for the construction of UNI Entrance B1 would be fully enclosed after piling works are completed to reduce the noise emission due to the excavation activities and construction of entrance. With reference to paragraph 4.5 of EIAO Guidance Note No. 9/2004, the use of noise enclosure could achieve a noise reduction of 15dB(A). The typical configuration of the full enclosure is shown in Figures 3.24.

Use of Alternative Quieter Construction Method

3.73 High level of noise exceedance would be encountered for sites which involve demolition of buildings. In view of this, concrete crusher (SWL=103dB(A)), which is a quieter alternative to conventional hydraulic breaker (SWL=110dB(A)), has been proposed for use at works areas where practicable.

3.74 Concrete crushers would be used for demolishing the Whitty Street Public Toilet in works area J2 (UNI Entrance B1), David Trench Rehabilitation Centre in works area M3 (SYP Entrance C), and Centre Street Cooked Food Market at works area M1 (SYP Entrances B1 and B2). The practicality of using concrete crushers at these locations has been confirmed by the Project Proponent.

Mitigated Construction Noise Impacts

3.75 With the implementation of all above-mentioned mitigation measures, the total SWLs of each activity were predicted, and are presented in Appendix 3.4. The predicted noise levels at most of the NSRs would comply with the EIAO-TM noise criteria. Table 3.12 presents the mitigated noise levels during normal daytime working hours at NSRs. A sample calculation of construction noise levels for mitigated scenario is presented in Appendix 3.4.

Table 3.12 Summary of Mitigated Construction Noise Levels during Non-restricted Hours

NSR ID	Description	Predicted Mitigated Construction Noise Levels, dB(A)			EIAO-TM Noise Criteria, dB(A)
KET 1	Kwun Lung Lau (Block 2)	64	-	74	75
KET 2	Luen Fat Apartments	62	-	73	75
KET 3	Luen Tak Apartments	60	-	76	75
KET 4	Smithfield Terrace (Block D)	56	-	76	75
KET 5	Pokfield Garden	51	-	77	75
KET 6	University Heights (Tower 2)	49	-	71	75
KET 7	Kam Po Mansion	50	-	76	75
KET 9	Hong Kong Institute of Vocational Education (Tsing Yi) Kennedy Town Centre	43	-	73	65/70^(1)
KET 10	LMC Primary School	59	-	70	65/70^(1)
KET 11	Cayman Rise (Block 1)	61	-	69	75
KET 12	Cheong Kat Building	41	-	65	75
KET 13	The Merton (Block 2)	40	-	65	75
KET 14	Kennedy Town Jockey Club Clinic	61	-	72	75
KET 15	Sisters of the Immaculate Heart of Mary (Kongmoon) Kit Sam Convent	64	-	75	75
KET P1	Kwun Lung Lau	59	-	70	75
UNI 1	Western Court (Block 1)	42	-	83	75
UNI 2	St. Louis School	42	-	66	65/70^(1)
UNI 3	Sun Court	43	-	72	75
UNI 4	The Belcher's (Tower 8)	44	-	68	75
UNI 5	PLK Chan Au Big Yan Home for the Elderly	44	-	75	75
UNI 6	Sun Shing Building	43	-	70	75
UNI 7	The Bauhinia	46	-	75	75
UNI 8	Hong Kong Chiu Sheung School	46	-	69	65/70^(1)
UNI 9	The Belcher's (Tower 3)	49	-	71	75
UNI 10	St. Paul's College Primary School	46	-	71	65/70^(1)
UNI 11	Sik On Building	47	-	77	75
UNI 12	Hill Court	45	-	77	75
UNI 13	Graceful Court	46	-	75	75
UNI 14	Wing Fu Lau	48	-	68	75
UNI 15	Yick Fung Garden (Block A)	42	-	72	75
UNI 16	Sunglow Building	42	-	73	75
UNI 18	Wah Po Building	43	-	75	75
UNI 19	Jade Court (Block A)	41	-	68	75
SYP 1	No. 18-20 Eastern Street	62	-	79	75
SYP 2	No. 28 Sai Woo Lane	61	-	77	75
SYP 3	No. 15 Tsz Mi Alley	66	-	77	75
SYP 4	Ngan Yu Building	65	-	81	75
SYP 5	Rich Court	62	-	82	75
SYP 6	Bon-Point	42	-	75	75
SYP 7	Bonham Road Government Primary School	42	-	74	65/70^(1)
SYP 8	Ivy Tower	43	-	86	75
SYP 9	Yee Shun Mansion	43	-	76	75
SYP 10	Chun King Court	43	-	82	75
SYP 11	Kiu Shing Building	43	-	82	75
SYP 12	No. 9-11 Ki Ling Lane	43	-	83	75
SYP 13	No. 9-15 Sai Yuen Lane	43	-	82	75
SYP 14	No. 1 Third Street	45	-	72	75
SYP 15	H.K.S.P.C Thomas Tam Day Nursery (A/C)	45	-	70	65/70^(1)
SYP 16	Wai Lee Building	68	-	83	75
GT 1	Overseas Trust Bank Building	41	-	74	75
GT 2	Princeton Tower	43	-	75	75
GT 3	Talon Tower	40	-	69	75
GT 4	Yu Hing Mansion	40	-	69	75
GT 5	Ka On Building	44	-	77	75
GT 6	Hongway Garden	44	-	77	75

Note: (1) EIAO-TM noise limits of L_{eq(30 min)} 70dB(A) for schools during normal hours (65dB(A) during examination periods)

3.76 With the implementation of mitigation measures, the preliminarily predicted noise levels at KET 15 during restricted hours due to the 24 hour operation of ventilation fans at the temporary magazine site would be 44 dB(A), which would comply with the NCO criteria.

Operation Phase

Fixed Plant

3.77 With the fixed plant properly designed to meet the maximum SWL listed in Table 3.9, there would not be any residual impact predicted. However, it is still recommended that the following noise reduction measures should be considered as far as practicable during detailed design:

§ Choose quieter plant such as those which have been effectively silenced.

§ Include noise levels specification when ordering new plant (including chillers and E/M equipment).

§ Locate fixed plant/louver away from any NSRs as far as practicable.

§ Locate fixed plant in walled plant rooms or in specially designed enclosures.

§ Locate noisy machines in a basement or a completely separated building.

§ Install direct noise mitigation measures including silencers, acoustic louvers and acoustic enclosure where necessary.

Evaluation of Residual Impacts

Construction Phase

3.78 Residual construction noise impacts were identified, as presented in Table 3.13 below.

Table 3.13 Predicted Residual Impacts Due to the Proposed Project

NSR ID	Location	Affected floor	Range of Residual Impact (dB(A))	Duration of Residual Impact (months)
KET 1	Kwun Lung Lau (Block 2)	-	-	-
KET 2	Luen Fat Apartments	-	-	-
KET 3	Luen Tak Apartments	1-5/F	1	2
KET 4	Smithfield Terrace (Block D)	1-12/F	1	2
KET 5	Pokfield Garden	1-4/F	1-2	3
KET 6	University Heights (Tower 2)	-	-	-
KET 7	Kam Po Mansion	1-5/F	1	3
KET 9	Hong Kong Institute of Vocation Education (Tsing Yi) Kennedy Town Centre	1-7/F	1-3	5
KET 10	LMC Primary School	-	-	-
KET 11	Cayman Rise (Block 1)	-	-	-
KET 12	Cheong Kat Building	-	-	-
KET 13	The Merton (Block 2)	-	-	-
KET 14	Kennedy Town Jockey Club Clinic	-	-	-
KET 15	Sisters of the Immaculate Heart of Mary (Kongmoon) – Kit Sum Convent	-	-	-
KET P1	Kwun Lung Lau	-	-	-
UNI 1	Western Court (Block 1)	1-10/F	1-8	6
UNI 2	St. Louis School	-	-	-
UNI 3	Sun Court	-	–	–
UNI 4	The Belcher's (Tower 8)	-	-	-
UNI 5	PLK Chan Au Yan Home for the Elderly	-	-	-
UNI 6	Sun Shing Building	-	-	-
UNI 7	The Bauhinia	-	-	-
UNI 8	Hong Kong Chiu Sheung School	-	-	-
UNI 9	The Belcher's (Tower 3)	-	-	-
UNI 10	St. Paul's College Primary School	1-7/F	1	3
UNI 11	Sik On Building	1 – 2/F	1 – 2	4
UNI 12	Hill Court	1/F	2	4
UNI 13	Graceful Court	-	-	-
UNI 14	Wing Fu Lau	-	-	-
UNI 15	Yick Fung Garden (Block A)	-	-	-
UNI 16	Sunglow Building	-	-	-
UNI 18	Wah Po Building	-	-	-
UNI 19	Jade Court (Block A)	-	-	-
SYP 1	No. 18-20 Eastern St	1-4/F	1-4	23
SYP 2	No. 28 Sai Woo Lane	1-3/F	1-2	6
SYP 3	No. 15 Tsz Mi Alley	1-5/F	1-2	9
SYP 4	Ngan Yu Building	1-6/F	1-6	26
SYP 5	Rich Court	1-21/F	7	4
SYP 6	Bon-Point	-	-	-
SYP 7	Bonham Road Government Primary School	1-2/F	2-4	19
SYP 8	Ivy Tower	1-5/F	1-11	27
SYP 9	Yee Shun Mansion	1/F	1	5
SYP 10	Chun King Court	1-5/F	1-7	15
SYP 11	Kiu Shing Building	1-4/F	1-7	10
SYP 12	No. 9-11 Ki Ling Lane	1-4/F	1-8	9
SYP 13	No. 9-15 Sai Yuen Lane	1-3/F	1-7	11
SYP 14	No. 1 Third Street	-	-	-
SYP 15	H.K.S.P.C Thomas Tam Day Nursery (A/C)	-	-	-
SYP 16	Wai Lee Building	3 – 9/F	2-8	5
GT 1	Overseas Trust Bank Building	-	-	-
GT 2	Princeton Tower	-	-	-
GT 3	Talon Tower	-	-	-
GT 4	Yu Hing Mansion	-	-	-
GT 5	Ka On Building	1/F	1-2	2
GT 6	Hongway Garden	1/F	1-2	2

3.79 Residual impacts of 1-11dB(A) would be expected, mainly due to the limited separation distance between NSRs and the works areas. The feasibility of providing noise reduction measures to further reduce the residual impacts has been examined, and discussed below.

Alternative Construction Method / PME

3.80 In view of the high noise exceedance during the construction phase of the Project, further mitigation measures have been explored. However, with the consideration of on-site condition and safety of site workers and passers-by, some mitigation measures are considered not practicable. For example, though the use of movable noise barriers is effective in reducing noise level, it would not be feasible to be used for demolition of existing buildings since the demolition process would start from the top of the buildings and erecting the barriers on the top floor of the buildings would give rise to safety issues. In addition, the number of movable noise barriers used on site should be restricted to minimize the chance of works site accidents and prevent the barriers from collapse. Further mitigation measures which are considered practical for implementation are discussed below.

Piling

3.81 For some of the works areas including Works Area C, D, M1, L1, M3 and M, using piling auger for installing pipe piles would cause residual impacts at some of the NSRs. Alternative piling method by using vibratory hammer or silent piler such as for installing sheet piles has been considered. This alternative would induce local deformation and thus considered to be unsafe and impractical.

Demolition of Buildings

3.82 Demolition of some existing buildings would involve the use of hydraulic breakers. Hydraulic breakers would have high noise emissions. For safety reasons, noise barriers could not be used to screen the noise generated by breakers. It has been suggested in the EIAO Guidance Note. 9/2004 that the use of concrete crushers instead of hydraulic breakers in the demolition of buildings could be considered for reducing the impacts. The practicality of using this alternative has been reviewed.

3.83 One major limitation of the concrete crusher is that its jaws would need to be able to get to both sides of the concrete element (beam, column, slab etc.) before it can crush or cut that element. This generally requires a number of holes to be cut into the structure at each floor level to enable the crusher to commence its work. The most effective way of making these holes in the structure is by replacing the jaws on the backhoe with a more conventional pneumatic breaker. This will obviously create as much noise as the more familiar method of concrete demolition but for a reduced period of time. For small structures, these holes in the structures can be made using concrete corer. However, for structures with considerable size / thickness of concrete elements that would need to be demolished, conventional hydraulic breakers should be deployed from a practical engineering viewpoint. This would be applicable to the case of Kennedy Town Swimming Pool demolition at Works Area D.

3.84 Demolition using a concrete crusher would be generally less controlled than demolition using a hydraulic breaker since it removes elements of the structure in larger pieces which then have to be lowered carefully to ground level. This is particularly difficult to control in buildings which have a small plan area such as those buildings at Sai Woo Lane, and tall structures such as Kennedy Town Ex-police Quarter.

3.85 The use of hydraulic breaker for demolishing David Trench Rehabilitation Centre at Works Area M3 cannot be fully replaced by the sole use of concrete crusher. The breaker has to be retained to form holes in the thick concrete elements of this building before the concrete crusher can work by getting to both sides of concrete element. However, concrete crusher would be used at this location wherever applicable, and the conventional demolition method would only be applied if absolutely necessary at specific part of the demolition such that the construction noise impact can be minimized.

3.86 It should also be noted that demolition using a concrete crusher would generally be 50% slower than the more conventional hydraulic breaker.

3.87 With the consideration of all mitigation measures and alternative construction methods, residual impacts are still predicted at some of the works areas. In view of the residual impacts, feasibility of adopting alternative construction methods/PME is further reviewed. Site-specific constraints of implementing various direct mitigation measures are also discussed below.

Works Area A – KET Ex-police Quarter

3.88 With the use of noise control curtain to screen the noise generated from the use of breakers, the demolition of the existing Kennedy Town Ex-police Quarters Block A & C would still cause residual impacts at NSR KET9.

3.89 Apart from using noise control curtain (Section 3.64 refers), the practicality of using movable barriers for reducing the residual impact due to demolition works has been reviewed. However, as the PME would be placed on top of the buildings to be demolished, it would be unsafe to erect movable barriers for the PME there. Therefore, it would not be feasible to use movable barriers in this case. It was considered that the use of noise control curtain would be the only feasible mitigation option for controlling the noise from demolition works based on available preliminary design information. It would also be recommended that noisy demolition works be scheduled as far as practicable to avoid examination hours in view of the predicted residual impacts at the school NSR (KET 9).

3.90 Having taken into account the above, it was considered that all direct mitigation measures have been exhausted and the construction noise impact at this works area has been minimized.

Works Areas C and D – KET Station Box

3.91 The construction of KET Station would be undertaken at these two works areas. Residual impacts were predicted at NSRs KET3-KET5 and KET7. Construction activities that would cause the residual impacts would include piling as well as demolition of the existing Kennedy Town Swimming Pool site.

3.92 During piling, the use of piling auger would generate high noise levels. However, as mentioned in Section 3.79, the use of alternative piling method would not be feasible in this works area. To abate the noise from the piling auger, noise insulating fabric has been proposed to cover the plant and a noise reduction of 10dB(A) could be achieved. The practicality of various mitigation measures for ameliorating other PME including cranes and trucks has been reviewed. Yet, as piling would be carried out along the site boundary, mitigation measures such as movable noise barriers would not be feasible due to spatial limitation.

3.93 Rock drill, which would be the noisiest PME amongst various equipment to be used, has been proposed for excavation works at these two works areas. Such would be needed for excavation of rock. To specifically control the emission of noise from this key source of noise impact, an acoustic enclosure as mentioned in Section 3.60 has been proposed to cover this equipment. It was envisaged that 20dB(A) noise reduction could be achieved by using the acoustic enclosure to cover the rock drill.

3.94 Demolition of the existing Kennedy Town Swimming Pool would result in residual impacts at NSRs nearby. As mentioned above, movable barriers would be unsafe and not feasible for screening the noise generated from the equipment when demolition works are undertaken. The use of concrete crusher instead of hydraulic breakers has then been considered. However, as mentioned in Section 3.81, given the considerable size / thickness of concrete elements of the swimming pool structure, the use of hydraulic breakers would be necessary.

3.95 In addition, temporary noise barriers would be provided along the southern and northern boundary of the works area C after piling. The noise levels from various construction activities such as excavation and construction of station box would be lowered with the temporary barriers in place. Based on the construction noise calculation, no noise exceedance would be predicted for those construction activities with temporary barriers in place. Therefore, the erection of temporary barriers along site boundary is considered effective in alleviating the construction noise impact.

3.96 With the use of all practicable direct mitigation measures and alternative construction methods/PME, it is considered that the construction noise impact due to the use of PME for various construction activities at these two works areas has been minimized.

Works Area J2 – UNI Entrance B1

3.97 Key activities to be undertaken at this works area would include the demolition of the existing Whitty Street Public Toilet, piling, excavation and construction of entrance. Construction activities at this works area would result in residual impacts at NSR UNI 1, which is located immediately next to the works area.

3.98 The residual impact would primarily be due to the demolition activity. In view of the large residual impact, quieter alternative demolition including the use of concrete crusher, which has a much lower SWL, has been adopted instead of the conventional use of hydraulic breaker. Noise level would be reduced with the use of concrete crusher. Additionally, enclosure would be applied to concrete corer such that the noise levels could be further reduced.

3.99 The use of movable noise barriers during demolition has also been reviewed. However, it was considered not practical during the demolition of the toilet block due to spatial limitation and safety reasons.

3.100 Another construction activity which would lead to residual impact would be piling. The large residual impact is due to the fact that NSR UNI 1 would be located immediately next to the works area boundary at which piling works would be carried out. To reduce the construction noise impact, the practicality of using various direct mitigation measures during piling has been reviewed. Pile rig would be the nosiest PME to be used, and it is proposed that a noise insulating fabric would be used to cover it to achieve a noise reduction of 10dB(A). Furthermore, there would be insufficient space for erecting noise barriers during piling. Given these engineering constraints, mitigation measures to further reduce the residual impact from piling works were not available.

3.101 Excavation would also result in high residual noise impacts at NSR UNI1. To further minimize the construction noise impact, the entire works area would be fully enclosed after piling. As mentioned in Section 3.71, the provision of full noise enclosure at this works area could achieve a noise reduction of 15dB(A). The SPL generated from the excavation activities and construction of entrance would be reduced with the full noise enclosure in place.

3.102 It was considered that all direct practicable noise mitigation measures have been exhausted, and alternative quieter construction method/PME would be used where practicable to minimise the residual noise impacts due to works conducted at this works area.

Works Area I – UNI Entrance C1, VS and Chiller

3.103 Minor residual impact would be expected at the school NSR UNI10 located in proximity of this works area. The use of pile extractor and power rammer for reinstatement works at this works area would be the main reason for the predicted residual impact. Noise insulating fabric has been proposed to control the emission of noise from the operation of these two PME. However, other feasible direct mitigation measures to further reduce the residual noise impact were not available. The residual construction noise impact was considered to be controlled to a minimum level with the proposed mitigation measures in place.

Works Areas J – UNI Entrance B2

3.104 The use of pile rig for piling works at this works area would result in high construction noise levels at neighbouring NSRs. Noise insulating fabric has already been proposed to alleviate the noise impact associated with the use of this PME. With this mitigation in place, NSR UNI12 would still be subject to slight residual impact when piling works would be conducted. Residual impact could be further reduced by enclosing the pile rig. However, in view of the nature of the piling works and size of the pile rig, using enclosure to cover the pile rig was considered not feasible. Alternative piling method by using vibratory hammer or silent piler has been rejected based on the reasons given in Section 3.79. The predicted residual impacts have been minimised as no further practical direct mitigation measures were available.

3.105 Excavation would also generate high construction noise levels at this works area. To abate the noise level during excavation, decking over has been proposed to cover the noise from the construction shaft. However, decking could not be installed at early stage of excavation. Sufficient depth would need to be excavated to allow adequate underground working space for the excavation to be proceeded before the ground opening could be covered with the decking. Hence, for conservative noise assessment, it was assumed that the deck would not be provided at initial stage of excavation i.e. weak rock excavation. The deck was assumed to be in place when rock excavation is conducted.

3.106 The feasibility of using NIC to cover the operation of PME during excavation has been examined. Nevertheless, since the construction shaft would take up almost the entire works area, there would be insufficient space to construct the necessary foundation for the NIC. Hence, it would not be feasible to adopt this mitigation option.

3.107 Residual construction noise impacts due to works at this location have been minimised as all practicable mitigation measures including the use of movable noise barriers, deck over, enclosure, silencer and noise insulating fabric have already been exhausted.

Works Areas J1 – UNI Vent Shaft Y

3.108 Minor residual impacts of 1-2 dB(A) were predicted at NSR UNI 11 which is located at about 10m away from the works area. Major activities that lead to the residual impact would include piling, excavation and reinstatement of the works area.

3.109 As revealed from the construction plant inventories, pile rig would have the highest noise emission level among all other PME used for piling. Noise insulating fabric which could achieve 10dB(A) noise reduction has been proposed to cover the pile rig. However, minor residual impact would still be predicted. To further reduce the construction noise impact, it would be necessary to identify practical measures which could reduce the noise emission from the pile rig by more than 10dB(A). One possible option would be the use of noise enclosure. However, as discussed in Section 3.102, given the nature of the piling works and size of the pile rig, noise enclosure would not be a feasible option. Alternative piling method by using vibratory hammer or silent piler has been rejected based on the reasons given in Section 3.79. The predicted residual impacts have been minimised as further practical direct mitigation measures were not available.

3.110 Throughout the process of excavating the shaft and horizontal adit, noise insulating cover could be employed for covering the opening of the shaft such that the noise from the PME beneath could be reduced. A noise reduction of up to 20dB(A) could be achieved after the use of this mitigation. However, minor residual impact would still be predicted. Practical mitigation measures to further reduce the residual impacts are not available.

3.111 It was predicted that the reinstatement works would also result in minor residual impact at the NSR UNI11. It can be observed that power rammer, being the nosiest PME, would be covered by a noise insulating fabric. Mitigation measures for other noisy plants, including truck, vibratory roller, concrete lorry mixer and asphalt paver have also been explored. However, due to the mobile nature of these equipment, further practical mitigation measures were not available. In particular, the use of movable noise barrier or noise enclosure would be considered not practical.

3.112 All direct mitigation measures have been looked into and applied where practicable to minimise the noise impacts due to works at this location.

Works Areas N1 – SYP Entrance A1&A2

3.113 The use of PME for demolishing existing buildings and excavation activities would result in residual impacts at NSRs SYP 1-5 and 16. The practicality of various mitigation proposals to further alleviate the residual noise impact has been examined.

3.114 Due to spatial constraints and safety concerns, the use of movable noise barriers for shielding the noise from the use of PME for demolition was not recommended. Alternative quieter demolition method such as the use of concrete crusher has also been considered. This option was however discarded based on reasons given in Section 3.82. Conventional demolition method using hydraulic breaker was assumed to be used at this works area.

3.115 The practicability of using noise control curtain was also investigated for the demolition works. This works area is a highly congested site when compared with the Ex-police quarter site. There would not be enough space to support the scaffold robust required supporting the noise control curtain and the substantial supporting structure required supporting the heavy weight of the fabric. Therefore, the use of noise control curtain is not recommended at this stage. However, the practicality of using the noise control curtain in this works area could be subject to further investigation in the detailed design stage.

3.116 The use of truck for transporting spoil from excavation works would be the other cause of the residual impact. However, due to its mobile nature, it would not be feasible to use mitigation measures such as movable noise barrier and noise enclosure. In addition to trucks, noise from hand-held breakers and backhoes would also contribute much to the high noise level. In view of this, movable noise barrier has been proposed for these two PME to alleviate the associated nose impact. Rock drill would be used during excavation to tunnel level. Given this PME would have a high noise emission level, an acoustic enclosure has been proposed to cover this equipment such that its noise emission level could be cut by about 20dB(A).

3.117 To further control the noise impact, a NIC would be used to cover the mucking out point upon commencement of tunnel construction. The NIC would help reduce the noise due to mucking out activities. It should be noted that the feasibility of providing the NIC at earlier stage of excavation works such as immediately after the completion of piling has been examined. However, since this works area would be used as the launching shaft for the TBM, the NIC could only be installed following the launching of the two TBM for tunnel construction. As a result, it was assumed in the calculation that the NIC would only be in place upon commencement of tunnel construction.

3.118 Temporary barriers have been proposed to shield the noise from the water cooling towers that would be used during tunnel construction. Further reduction in noise impact could be achieved by using full enclosure. However, operating cooling towers in an enclosure would have heat dissipation problems.

3.119 Other noise mitigation measures including movable barriers, noise insulating fabric, silencer and enclosure have been proposed to ameliorate the noise impact due to the use of various PME for different construction activities at this works area. The noise impacts arising from works at this location have been minimised through the adoption of all practicable mitigation measures discussed above.

Works Areas M3 – SYP Entrance C

3.120 It was predicted that the demolition of existing David Trench Rehabilitation Centre and excavation activities at this works area would lead to residual noise impact at the school NSR SYP7 .

3.121 A review of the practicality of using alternative quieter concrete crusher for demolition works at David Trench Rehabilitation Centre has been conducted. As discussed in Section 3.83, the use of hydraulic concrete crusher will be used locally for specific demolition works wherever applicable to minimise the construction noise impact. However, the hydraulic breaker would be retained to make initial holes through thick concrete slabs and structural walls especially those with steel reinforcement. However, the use of the breaker would play a supplementary role and so its utilization rate would only be in the order of 30%. The concrete crusher would be used as far as practicable to minimise the noise impact from the demolition works.

3.122 The feasibility of adopting other direct mitigation measures for the demolition works at this works area has been reviewed. The use of movable noise barrier is considered impractical and unsafe to be placed on top of the building to be demolished. Though trucks would be placed on ground level, it would not be viable to use either movable barriers or noise enclosures to screen the noise since they are mobile in nature. In this regards, noise impact caused by demolition works at this works area could not be reduced further as no other practicable mitigation measures would be available.

3.123 Throughout the entire excavation process, NIC would be provided to cover the opening of the shaft. Those PME used for excavation would be placed underneath the cover such that the noise could be effectively screened. A noise reduction of 20dB(A) could be achieved with the use of NIC. For those PME including dump trucks, cranes and concrete lorry mixer which have to operate outside the cover, other direct mitigation measures have also been considered. However, it would be not be practicable to use movable noise barriers or noise enclosures to cover these mobile equipment. Further practicable measures to mitigate the noise impact were not available.

3.124 The use of trucks during the carrying out of station fitout would also cause minor noise exceedance. Similarly, due to the mobile nature of trucks, no mitigation measures could be provided to alleviate the noise impact.

3.125 Having taken into consideration the above factors, the mitigation proposal in this works area is considered to be exhausted and the construction noise impact has been minimized.

Works Areas M1 – SYP Entrance B1 & B2

3.126 Piling, excavation, demolition of the Centre Street Market West Block and station fitout would result in residual impacts at NSRs SYP8-10 located in close proximity to this works area. Mitigation measures to further ameliorate the predict residual impact have been considered.

3.127 Piling works would be conducted at the works area boundary. The separation distance between NSRs and the location at which piling works would be carried out would be small, and this would be the main reason for the noise exceedances. Amongst various equipment to be used for piling, piling auger would be the noisiest equipment. A noise insulating fabric which would result in a noise reduction of 10dB(A) has been deployed to cover the noise from this noisiest equipment. However, residual impact would still be predicted. Either the use of mitigation measure such as noise enclosure which could cut the noise from the use of piling auger by more than 10dB(A) or alternative piling method using quieter PME such as vibratory hammer or silent piler could further ameliorate the residual impact. Given the nature of the piling works, noise enclosure for covering the piling auger would not be a practicable option. The use of alternative piling method mentioned above has been considered but such method could possibly cause local deformation and therefore was not recommended. Cranes and trucks would also be used during piling. However, due to their mobile nature and spatial limitation, the use of movable noise barriers and noise enclosures would not be feasible. It was considered that all practicable mitigation measures have been exhausted and residual noise impacts due to piling works have been minimised.

3.128 Another construction activity which would lead to the noise exceedance would be demolition of the Centre Street Market West Block. Having reviewed the site conditions, concrete crusher instead of hydraulic breaker has been proposed for carrying out the demolition works at this location. Noise impact resulted from the use of this alternative demolition method would generally be lower than that from the use of conventional method using hydraulic breakers.

3.129 A concrete corer would be needed in conjunction with the use of concrete crusher. To mitigate the noise impact from this PME, a noise enclosure which could achieve a noise reduction of 15dB(A) has been proposed. In addition, the practicality of using movable noise barrier during demolition was also reviewed. Similar to other works area where demolition would take place, placing movable noise barrier on top of the building to be demolished would have construction safety issues. Practicable mitigation measures to further reduce the extent of residual impact were not available.

3.130 The excavation process at this works area would also cause the noise exceedance. To reduce the noise impact, a NIC has been proposed to cover the opening of the shaft throughout the excavation process. Similar to the situation in works area M3 – SYP Entrance C (Section 3.120 refers), the NIC could reduce the noise emissions by about 20dB(A). PME operating outside the NIC including trucks and crane would be mobile, and thus would not be possible to cover them by using enclosure or movable barriers.

3.131 Similar to the situation in works area M3 – SYP Entrance C, the use of trucks for station fitout would also cause residual noise impact. No mitigation measures could be provided due to the mobile nature of the trucks.

3.132 All practicable measures have been exhausted and residual noise impacts that would arise from the execution of works at this location have been minimised.

Works Areas L1 – SYP Entrance B3

3.133 Residual impact would be predicted at NSRs SYP 11-13 surrounding this works area. Piling, excavation and construction activities that would take place in the soft ground tunnel would be main reasons of the residual impact.

3.134 Similar to the situation in Works Area M1 - SYP Entrance B1 & B2, since the NSRs are in close proximity to the site boundary at which piling would take place, and it would not be feasible to use alternative quieter piling method, piling would give rise to residual impacts at the surrounding NSRs. The use of noise insulating fabric is considered to be the only practicable mitigation measure to screen the noise from the piling auger. Further reduction in noise levels can be achieved by covering the piling equipment with a NIC. However, since this works area would be extremely tight, space available for erecting the NIC would be highly limited. In particular, since this works area is highly congested, there would not be sufficient space for providing the necessary foundation of the NIC.

3.135 In light of the predicted noise exceedance, the use of decking has been proposed to minimize the noise levels generated from the construction activities in the soft ground tunnel. By covering the opening of the shaft with a deck, a noise reduction of 20dB(A) can be achieved. As mentioned in Section 3.70, there would not be any opening at the deck such that noise would not leak out from the deck. As the soft ground tunnel is excavated, the excavated material would not be transported out of the tunnel to ground level at this works area. Instead, they will be transported to the nearby mucking out shaft at Sai Woo Lane. Therefore, it can be perceived that there would not be any opening at the deck for mucking-out purpose, and the deck could serve as an enclosure to fully cover the opening of the shaft to achieve the assumed noise reduction.

3.136 Because of the congested environment of this works area, residual noise impacts have been minimised as far as possible by deploying all available practicable mitigation measures. However measures to further ameliorate the residual impacts could not be provided because of the tight environment of this works area.

Works Areas O3

3.137 Minor residual impact would be anticipated at NSRs GT5 and GT6, which are in proximity to this Works Area O3. The noise exceedance would possibly be due to the small separation distance between the impacted NSRs and the works area.

3.138 Drill rig and power rammer would be the nosiest PME used in this works area. To reduce their associated noise impact, noise insulating fabric has been proposed to screen the noise generated from them to the NSRs. Noise reduction of 10dB(A) would be achieved with this mitigation measures in place.

3.139 Movable noise barrier and noise enclosure have also been recommended where practical. With the use of all practicable noise mitigation measures, the construction noise impact arising from this works area has been minimized.

Indirect Technical Remedies

3.140 Residual noise impacts have been minimised through exhausting all practicable direct noise mitigation measures including the use of quieter plant, temporary / movable noise barriers, noise enclosure/acoustic shed, “Noise Control Curtain”, silencers, noise insulating fabric, noise insulating cover, acoustic enclosure and decking over the excavation area / shaft as far as practicable. Having reviewed the site constraints and nature of works to be undertaken at various works areas, it is considered that all practicable mitigation measures have been exhausted and residual impacts minimised.

3.141 Because of the close proximity to the NSRs, further direct mitigation measures would not be practicable in eliminating all construction noise exceedance. Indirect Technical Remedies (ITR) is therefore considered for minimizing the construction noise impacts.

3.142 It should be noted that the use of ITR as a mitigation measure is neither a requirement stipulated under Annex 13 of the EIAO-TM nor the EIA Study Brief. The provision of ITR is the initiative of the Project Proponent in view of the noise disturbance associated with the construction of the WIL. ITR would generally require the consideration to upgrade the glazing if necessary for the noise sensitive facades exposed to excessive residual noise impact. The provision of air-conditioning would also be considered for those affected dwellings.

3.143 With reference to the East Rail Extension Hung Hom to Tsim Sha Tsui EIA Final Report (ERE-EIA Report), the eligibility criteria proposed for qualifying NSRs for ITR would be dependent on the severity of the residual noise impact and duration of exceedance after implementing all practical direct mitigation measures. The eligibility criteria set out in the ERE-EIA Report are:

i. The affected household would be subject to a residual noise impact of 5 dB(A) or above;

ii. The duration of the residual noise impact at the building façade of the household would be 1 month or more.

3.144 Based on the assessment results presented in Appendix 3.4, residual impacts which would be in excess of 5dB(A) and last for one month or more would be predicted at NSRs located in the proximity of the following works areas:

i. UNI Entrance B1

ii. SYP Entrance A1 & A2

iii. SYP Entrance B1 & B2

iv. SYP Entrance B3

3.145 NSRs which would be considered eligible for providing ITR as per the two criteria set out in the ERE-EIA are listed in Table 3.14 below and depicted in Figure 3.19 – 3.20.

Table 3.14 NSRs Eligible for the Provision of ITR

Works Area	Locations	Total no. of floors	Estimated no. of affected dwellings per floor (with noise exceedance>5dB(A))	No. of floors requiring ITR	No. of dwellings requiring ITR
UNI Entrance B1	Western Court (Block 1)	10	2	4	8
SYP Entrance A1 & A2	Ngan Yu Building	6	3	6	18
	Rich Court	21	1	14	14
	Wai Lee Building	6	1	6	6
SYP Entrance B1 & B2	Ivy Tower	29	4	3	12
	Chun King Court	27	2	2	4
	First Street No. 79-81	5	2	2	4
	First Street No. 77	4	1	2	2
	First Street No. 75	4	1	2	2
SYP Entrance B3	Sai Yuen Lane No.1	6	1	1	1
	Sai Yuen Lane No.3	5	1	1	1
	Sai Yuen Lane No.5-7	5	2	1	2
	Sai Yuen Lane No.9-15	5	4	1	4
	Sai Yuen Lane No.21	5	1	1	1
	Sai Yuen Lane No.23	4	1	1	1
	Sai Yuen Lane No.25	5	1	1	1
	Chung Ching Street No. 1-3	5	2	2	4
	Chung Ching Street No. 5	5	1	2	2
	Chung Ching Street No. 7	6	1	2	2
	Chung Ching Street No. 9-11	5	2	2	4
	Chung Ching House	5	4	2	8
	Chung Ching Street No. 21	5	1	2	2
	Kiu Ching Building	8	3	2	6
Total no. of dwellings requiring ITR					109

Notes: the number of affected dwellings per floor was estimated based on information obtained from site visits conducted in October 2006.

Operation Phase

3.146 No adverse operational residual noise impact would be envisaged if the noise emissions from the proposed fixed plant are designed to meet the Max SWL with appropriate noise reduction measures in place.

Environmental Monitoring and Audit

Construction Phase

3.147 An Environmental Monitoring and Audit (EM&A) programme is recommended to be established according the predicted occurrence of noisy activities. The recommended mitigation measures should be implemented during construction stage. Details of the programme are provided in a stand-alone EM&A Manual.

Operational Phase

3.148 Prior to the operation phase of the Project, a commissioning test should be conducted to ensure compliance of the operational airborne noise levels with the EIAO-TM noise criteria. Details of the EM&A programme are provided in a stand-alone EM&A Manual.

Conclusion

Construction Phase

3.149 Noise arising from the construction activities of the project would have unavoidable potential impact on the NSRs located in the vicinity of the works areas. Unmitigated cumulative construction noise levels at the representative NSRs are predicted, which are found to be in the range of 40 to 98 dB(A), exceeding the EIAO-TM daytime construction noise limit by up to 23 dB(A).

3.150 Mitigation measures are recommended to reduce the noise levels to within the EIAO-TM noise criterion, including good site practices, quieter plant, silencer, movable noise barrier, temporary noise barrier, noise enclosure, noise insulating fabric, “Noise Control Curtain”, acoustic enclosure, noise insulating cover and decking over the excavation area/ shaft. With the recommended mitigation measures in place, noise levels at most of the NSRs are predicted to comply with the EIAO-TM daytime construction noise criterion and no adverse residual construction noise impact is expected. Some NSRs, including KET3-5, KET7, KET9, UNI1, UNI10-12, SYP1-5, SYP7-13, SYP16 and GT5-6 located in close proximity to the works areas, would still be exposed to noise levels exceeding the EIAO-TM noise criteria. The ITR has been considered for minimizing the residual construction noise impacts for these affected NSRs. The provision of ITR is neither a requirement stipulated under Annex 13 of the EIAO-TM nor the EIA Study Brief, and is the initiative of the Project Proponent in view of the noise disturbance associated with the construction of the WIL. Based on the criteria developed in the East Rail Extension Hung Hom to Tsim Sha Tsui EIA Final Report (ERE-EIA), NSRs which were considered to be eligible for ITR provision were identified.

3.151 Based on the current design, there would be two ventilation fans operating in the magazine adit during restricted hours, and would require the application of CNP under the NCO. To evaluate whether construction works in restricted hours are feasible, preliminary construction noise impact assessment has been carried out and the assessment results showed that with the implementation of mitigation measures, the predicted noise level at the representative NSR would comply with the NCO criteria. However, it should be noted that the assessment result is indicative only and the Noise Control Authority will only consider an application based on the NCO, the relevant technical memoranda issued under the NCO, the contemporary condition/situations of adjoining land uses and any previous complaints against construction activities at the site. The assessment result in this EIA Report would not bind the Noise Control Authority in making its decision in granting a CNP.

Operation Phase

3.152 The assessment results indicated that predicted noise levels at all NSRs arising from the fixed plant of the Project would comply with the EIAO-TM criteria, with the noise emissions from the fixed plant controlled to achieve the specified Max SWL by proper noise reduction measures. Thus, no adverse fixed plant noise impacts would be expected.