4.1.1.1 Potential construction air-borne noise impacts may be generated due to the use of powered mechanical equipment (PME) for various works activities including site formation, foundation construction and construction of maintenance areas, plant rooms and utilities. Further details on the construction activities, programme and equipment are provided in Section 4.5 below
4.1.1.2 During the operation of the workshop, operational noise impacts could be generated from the vehicle maintenance activities. No fixed plant noise associated with ventilation fans or chillers have been identified and, therefore, these have not been assessed. However, the potential for off-site noise impacts from the vehicles using the Workshop will also be assessed.
4.2
Environmental
Legislation, Standards and Guidelines
4.2.1.1 The Noise Control Ordinance (NCO) and the EIAO provide the statutory framework for noise control. Assessment procedures and standards relevant to this project are set out in the Technical Memoranda (TM) given below.
·
The TM on Environmental Impact Assessment Process (EIAO-TM);
·
The TM on Noise from Construction Work other than Percussive Piling
(GW-TM);
·
The TM on Noise from Construction Work in Designated Areas (DA-TM); and
·
The TM for the Assessment of Noise from Places Other Than Domestic
Premises, Public Places or Construction Sites (IND-TM).
4.2.1.2 No percussive piling is proposed for the project and as such the Technical Memorandum on Noise from Percussive Piling will not be relevant to the noise assessment and is not discussed further. Notwithstanding, Percussive Piling is prohibited at any time on Sundays and public holidays and during the weekday evening and night-time hours (1900-0700hrs, Monday through Saturday) and a Construction Noise Permit (CNP) would be required if such works were eventually needed.
Noise Standards for Non-restricted Hours
4.2.2.1 Daytime construction noise (excluding percussive piling) between the hours of 0700 and 1900 on weekdays, i.e. non-restricted or normal working hours, is governed by the EIAO-TM. Annex 5 of the EIAO-TM sets out the construction noise assessment limits, which are Leq(30 min) 75dB(A) for domestic premises and hotels, and Leq(30 min) 70dB(A) for educational institutions including kindergartens (or 65dB(A during examination periods), nurseries and all other places where unaided voice communication is required. The recommended noise standards are summarised in Table 4.1 below.
Table
4.1: Daytime
Construction Noise Limits
|
Uses |
Noise
Standard, Leq,
30 mindB(A) |
|
Domestic premises, hotels and hostels |
75 |
|
Educational institutions, kindergartens, nurseries
and all others where voice communication is required |
70 (65 during examination period) |
Note:
The above
criteria apply to noise sensitive uses which rely on open window for
ventilation and should be viewed as the maximum permissible noise levels
assessed at
Noise Standards for Restricted Hours
4.2.2.2 During restricted works periods between 1900 and 0700 hours from Monday to Saturday and at any time on Sundays or public holidays, activities involving the use of PME for the purpose of carrying out construction work is prohibited unless a Construction Noise Permit (CNP) has been obtained.
4.2.2.3 The GW-TM provides details of the procedures adopted by the EPD for assessing such applications. The granting of a CNP is subject to the conditions as stated in the CNP, which may be revoked at any time for failure to comply with the permit conditions. A CNP may be granted in cases where the noise can be contained within the Acceptable Noise Level (ANL) at the Noise Sensitive Receivers (NSRs). ANLs are assigned depending on the Area Sensitivity Ratings (ASRs) of the study area. The ANLs for construction works in Designated Areas are more stringent than those given in the TM-GW.
4.2.2.4 Under the DA-TM, the use of five types of SPME and three types of Prescribed Construction Works (PCW) within a designated area during restricted hours would require a valid CNP. The SPME includes a 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; and
·
Hammering.
4.2.2.5 In general, it cannot be presumed that a CNP would be granted for carrying out PCW within a designated area during restricted hours but it may be granted if the relevant ANLs and criteria stipulated in the GW-TM and DA-TM can be met.
4.2.2.6 As defined in the latest Noise Control Designated Area Plan (Plan No. EPD/AN/HKI-01), the whole project works area is within the Designated Area. The corresponding basic noise levels (BNLs) for evening and night-time periods are given in Table 4.2 and the figures in brackets for designated areas would also apply to this project.
Table 4.2: Construction
Noise Criteria for Activities other than Percussive Piling
|
Time
Period |
Basic
Noise Levels (BNLs), dB(A) |
||
|
ASR ‘A’ |
ASR ‘B’ |
ASR ‘C’ |
|
|
Evening (1900 to 2300 hrs)[a] |
60 (45) |
65 (50) |
70 (55) |
|
Night-time (2300 to 0700 hrs) |
45 (30) |
50 (35) |
55 (40) |
[a] Includes Sunday and Public
Holidays during daytime and evening.
Figures in brackets are BNLs
for Specified Powered Mechanical Equipment (SPME) construction work in
designated areas.
4.2.2.7 As noise in restricted periods is covered by the NCO, it is not assessed further in this EIA under the EIAO and despite any reference made in this EIA Report on construction noise aspects during restricted periods, there is no guarantee that a 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 TM issued under the Noise Control Ordinance. The Noise Control Authority will take into account contemporary conditions/situation of adjoining land uses and any previous complaints against construction activities at the site before making his decision in granting a CNP. Nothing in the EIA Report shall bind the Noise Control Authority in making his decision. If a CNP is to be issued, the Noise Control Authority shall include in it any condition seen fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.
4.2.2.8 According to the construction programme listed in Section 3, all the proposed construction works are expected to 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 a CNP application to the Noise Control Authority and abide by any conditions stated in the CNP, should one be issued.
Fixed Noise
4.2.3.1 The NCO and IND-TM control noise from operational noise from places or premises other than domestic premises, public places or construction sites. For the assessment of impacts from these noise sources, the Area Sensitivity Ratings (ASR) of the NSRs must be determined in accordance with the IND-TM, and then based on the ASR, the appropriate ANL can be determined. There are four types of areas described in the IND-TM which are summarised in Table 4.3 below.
Table 4.3 Area
Sensitivity Ratings of NSRs
|
Type of
Area Containing NSR |
Degree to which NSR is affected by Influencing
Factors (IFs) |
||
|
Not Affected |
Indirectly Affected |
Directly Affected |
|
|
(i) Rural
area, including country parks, or village type developments |
A |
B |
B |
|
(ii) Low
density residential area consisting of low-rise or isolated high-rise
developments |
A |
B |
C |
|
(iii) Urban
area |
B |
C |
C |
|
(iv) Area
other than those above |
B |
B |
C |
4.2.3.2 The ANLs based upon the different ASRs are shown in Table 4.4 below.
Table 4.4: Acceptable
Noise Level during Operational Phase
|
Time
Period |
NCO
Criteria |
EIAO-TM |
||||
|
ASR ‘A’ |
ASR ‘B’ |
ASR ‘C’ |
ASR ‘A’ |
ASR ‘B’ |
ASR ‘C’ |
|
|
Daytime and Evening (0700-2300 hrs) |
60 |
65 |
70 |
55 |
60 |
65 |
|
Night-time (2300-0700 hrs) |
50 |
55 |
60 |
45 |
50 |
55 |
Source –
IND-TM and EIAO-TM
4.2.3.3 According to The Annual Traffic Census of 2010 released by Transport Department, the Annual Average Daily Traffic (AADT) at Wing Tai Road Flyover is about 34,000 vehicles while the AADT for Island Eastern Corridor between Mong Lung Street and Wing Tai Road is about 54,000, so by definition there is an Influencing Factor (IF) within the study area. Since the NSRs are located within the urban area of Chai Wan, it is anticipated that an ASR of C would be allocated to the NSRs. This ASR is indicative only and the noise from the fixed sources is controlled under Section 13 of the NCO and nothing in this report shall bind the Noise Control Authority in the context of law enforcement against any fixed noise sources being assessed. The prevailing legislation, practices contemporary conditions and situation of adjoining land use should all be considered in determining noise impact.
4.2.3.4 However, besides the IND-TM ANLs, more stringent criteria for assessing fixed noise are recommended in the EIAO-TM for planning purposes. The recommended assessment criteria are:
·
Criteria (1): 5dB(A) below the appropriate ANL set out in the IND-TM (as
shown in Table 4.4); and
·
Criteria (2): The prevailing background noise level where this is 5dB(A)
below the appropriate ANL (i.e. ANL -5dB(A)).
4.2.3.5 Criteria (2) would be more stringent than Criteria (1) and would generally apply to areas with low ambient noise levels such as rural areas and suburban areas. The Project area is an urban area influenced by traffic noise from Wing Tai Road, Island East Corridor and Chai Wan Industrial Area. As noted from site inspections, the prevailing noise levels are unlikely to be 5dB(A) lower than the appropriate ANL and thus, EIAO-TM Criteria 2 would not be relevant. Thus, EIAO-TM Criteria 1 has been adopted for this urban study area as this is more conservative than the IND-TM levels.
Operational Traffic Noise
4.2.3.6 The TM-EIAO provides guidance on the acceptable road traffic noise levels at uses which rely on the open windows for ventilation. The relevant criteria are shown in Table 4.5 below.
Table 4.5: Road Traffic Noise Planning
Criteria
|
Common
Uses |
Road
Traffic Noise, L10 (1hour) dB(A) |
|
Domestic Premises |
70 |
|
Hotel and Hostels |
70 |
|
Offices |
70 |
|
Educational Institutions |
65 |
|
Places of public worship and courts of law |
65 |
|
Hospital & Clinics |
55 |
Note: The
above criteria apply to noise sensitive uses which rely on open window for
ventilation and should be viewed as the maximum permissible noise levels
assessed at
4.3.1.1 NSRs have been identified in accordance with Annex 13 of the EIAO-TM which can included domestic premises, temporary housing accommodation, educational institutions, nurseries, hospitals, medical clinics, homes for the aged, convalescent homes, places of public worship, libraries, courts of law, performing arts centres, auditoria, amphitheatres, hostels and country parks. Sensitive receivers present within the 300m study area boundary have been identified.
4.3.1.2 The construction site is located at Wing Tai Road and Sheung Ping Street opposite to Tsui Wan Estate and close to Hong Kong Institute of Vocational Education. The existing NSRs selected as representative for both the construction and operational noise assessments are listed in Table 4.6 and illustrated in Figure 4.1. Details of the NSRs are presented in Appendix 4.1.
4.3.1.3
According to the latest Chai Wan Outline Zoning Plan (OZP)
No.: S/H20/20, one third of the Project site is zoned as “Government,
Institution and Community (2)” and two thirds of the site as “Open Space”. Nevertheless, the Lands Department
(LandsD) allocated the Project site to EMSD in 2009 for a temporary period of 5
years under Temporary Land Allocation No. THK-1856. The land to the immediate west of the Project site is
zoned as “G/IC(2)” use and has been selected by the Education Bureau to develop
a future educational institute in terms of proposed land use. Thus, this area has been identified as a
future NSR with institutional use in the noise assessment during the operational
phase. As the future operator is
yet to be confirmed, no information on the layout of the building is
available. The NSR location has,
therefore, been selected at its site boundary i.e. the Project boundary, where
the horizontal distance is the shortest from the identified operational noise
sources for operational phase noise impact assessment as a worst case scenario.
Table 4.6: Representative
Noise Sensitive Receivers
|
Noise Sensitive Receiver |
Type |
No. of Storeys |
Distance from Site, (m) |
|
|
1 |
Tsui
Hong House, Tsui Wan Estate |
Residential |
30 |
74 |
|
2 |
Tsui
Shou House, Tsui Wan Estate |
Residential |
30 |
58 |
|
3 |
Tsui
Ching House, Hang Tsui Court |
Residential |
30 |
183 |
|
4 |
Hong
Kong Institute of Vocational Education (Chai Wan) |
Institutional |
7 |
225 |
|
5 |
Endeavourers
Chan Cheng Kit Wan KG |
Institutional |
1 |
58 |
|
6 |
SKH
Li Fook Hing Secondary School |
Institutional |
6 |
184 |
|
7 |
Chai
Wan Faith Love Lutheran School |
Institutional |
6 |
284 |
|
8 |
Planned
Educational Institute (Operational Phase Only) |
Institutional |
-- |
0 |
4.4.1.1 The project site is located in between the industrial and urban district of Chai Wan. The surrounding land uses comprise residential use at one side but with industrial areas on the other sides. Site visits conducted in 2011 revealed that the NSRs identified within the study area are exposed to the traffic noise along the existing road Wing Tai Road only which has AADT of about 23,000 in 2010. There are also two bus maintenance depots operated by Citybus and New World First Bus in the vicinity and these are about 150m and 380m, respectively (see Figure 4.2)
4.5
Identification
of Potential Noise Impacts
4.5.1.1 The potential sources of noise impact during the construction phase of the Project would be the use of Powered Mechanical Equipment (PME) for various construction activities. As broadly indicated in the construction programme in Appendix 3.1, the construction of the project would be tentatively starts from August 2012 and lasts for about 14 months while main construction activities would be completed in 12 months. The key construction activities to be carried out which are relevant to the construction noise assessment include:
·
Site Formation Works;
·
Construction of Concrete Footings;
·
Plumbing and Drainage System;
·
Erection of Steel Frame;
·
Installation of Sandwich Roof Panel;
·
Construction of Plant Rooms;
·
Construction of Concrete Floor Slab; and
·
Building Services Works.
4.5.1.2 The key PME to be used for the construction works activities are shown in Table 4.7 below. In order to provide a realistic assessment of the works activities, the percentages of time that the PME will be operating on site have also been considered when calculating the cumulative Sound Power Levels (SWL) for the construction activities. The noise levels at the NSRs have been assessed on a bi-weekly basis in respect to the individual noise levels induced by the construction works activities, assuming they are operating cumulatively. The geographical centre of the notional source is given in Figure 4.3.
Table 4.7: PME
Identified as Major Noise Sources
|
PME |
TM or other ref. |
No. of PME |
SWL,
dB(A) |
On
time, % |
Total
SWL |
|
1.
Site Formation Works |
|||||
|
Breaker,
hand-held, mass > 10kg and < 20kg |
CNP 024 |
1 |
108 |
50 |
113 |
|
Excavator/loader,
wheeled/tracked |
CNP 081 |
2 |
112 |
50 |
|
|
2.
Construction of Concrete Footing |
|||||
|
Concrete
lorry mixer |
CNP 044 |
2 |
109 |
100 |
115 |
|
Concrete
pump, stationary/lorry mounted |
CNP 047 |
2 |
109 |
100 |
|
|
Bar
bender and cutter (electric) |
CNP 021 |
3 |
90 |
50 |
|
|
Jig-saw,
hand-held, wood (electric) |
CNP 131 |
1 |
99 |
50 |
|
|
3.
Plumbing and Drainage System |
|||||
|
Excavator/loader,
wheeled/tracked |
CNP 081 |
2 |
112 |
50 |
114 |
|
Concrete
lorry mixer |
CNP 044 |
1 |
109 |
100 |
|
|
Jig-saw,
hand-held, wood (electric) |
CNP 131 |
1 |
99 |
50 |
|
|
4.
Erection of Steel Frame |
|||||
|
Crane,
mobile/barge mounted (diesel) |
CNP 048 |
1 |
112 |
70 |
114 |
|
Dump
truck |
CNP 067 |
1 |
117 |
30 |
|
|
Welding
Machine |
Not a PME |
3 |
0 |
100 |
|
|
5.
Installation of Sandwich Roof Panel |
|||||
|
Drill
rig, rotary type (diesel) |
CNP 072 |
3 |
110 |
70 |
115 |
|
Crane,
mobile/barge mounted (diesel) |
CNP 048 |
1 |
112 |
70 |
|
|
6.
Construction of Plant Rooms |
|||||
|
Concrete
lorry mixer |
CNP 044 |
2 |
109 |
100 |
115 |
|
Concrete
pump, stationary/lorry mounted |
CNP 047 |
2 |
109 |
100 |
|
|
Bar
bender and cutter (electric) |
CNP 021 |
2 |
90 |
50 |
|
|
Jig-saw,
hand-held, wood (electric) |
CNP 131 |
1 |
99 |
50 |
|
|
7.
Construction of Concrete Floor Slab |
|||||
|
Excavator/loader,
wheeled/tracked |
CNP 081 |
3 |
112 |
50 |
115 |
|
Concrete
lorry mixer |
CNP 044 |
1 |
109 |
100 |
|
|
Bar
bender and cutter (electric) |
CNP 021 |
1 |
90 |
50 |
|
|
Jig-saw,
hand-held, wood (electric) |
CNP 131 |
1 |
99 |
50 |
|
|
8.
Building Services Works |
|||||
|
Drill,
hand-held (battery) |
CNP 071 |
3 |
89 |
50 |
91 |
4.5.1.3 The proposed plant inventory involves the use of SPME, as detailed in Section 4.2.2.4, including hand held breakers, concrete lorry mixers and dump trucks. As such, should construction works extend into restricted hours, the DA-TM will become effective and further restriction on the acceptable noise will be imposed.
Background
4.5.2.1 During the operational phase, fixed plant noise sources could arise from the maintenance activities for the vehicles and engine noise emission from the vehicles during commissioning tests. The relevant brochure for the equipment to be operating within the workshop has been provided in Appendix 4.2. The potential sources are discussed below.
Fixed Plant Noise
4.5.2.2 As the workshop will use natural ventilation afforded by an open shelter, no extraction or ventilation fans are proposed. As there are no fixed plant such as ventilation fans or cooling towers in the proposed workshop, assessment of the maximum allowable SWL at the fixed plant would not be required.
Workshop Equipment and Tests
4.5.2.3 The workshop will be provided with a variety of equipment but not all would be considered as a significant noise source. The typical equipment in the workshop is detailed in Section 3. Their descriptions with respect to the operational noise assessment are provided as follows and their locations are shown in Figure 4.4.
·
Air Compressors – They will be employed for providing power to the pneumatic tools for
vehicle maintenance activities and also the 6 motorcycle hoists are small scale
only (air deliver rate at 1,130 L/min and air pressure at 13 bar as shown in Appendix 4.2). Regarding its small output, it would not
be expected to generate significant noise.
In addition, the air compressors will be housed in a dedicated
compressor room which will isolate the noise generated from this equipment and
contain any noise impact during operation to within the Workshop area. As such, the compressors would not be
considered as a source of noise for the operational noise assessment.
·
Hand-held Pneumatic Tools – They include small wheel wrenches, small
jacks, tyres inflators and pumps for used lube oil pumping in the form of
hand-held wheel wrenches that can also be used as screw drivers used to unlock
and tighten bolts during wheel changing, small jacks, tyre inflators and pumps
that used for used lube oil pumping.
The wheel wrenches are small in scale and generate minimal noise during
operation. Compressed air being
used for small jacks and tyre inflators are contained within cylinders and,
thus, no noise would be generated. The
lube oil pumps do not offer high suction powers and the noise generated during
operation was also considered minor.
·
Vehicle Lifting Hoists – A total of 11 vehicle lifting hoists for vehicles would be provided
in the Workshop. As shown in Appendix 4.2, the hoists are
electrically powered with small output motors. They are thus considered quiet with
minimal noise generation.
·
Roller Brake Tester – The workshop will be equipped with a roller brake tester. During brake testing, the roller brake
tester will run the vehicle’s front wheel or rear wheel at a low speed, while
the vehicle will have its engine switched off. The operator will then apply the brake
of the vehicle under testing and will eventually lock the respective
wheel. The brake tester will then
record the maximum torque and the vehicle is pushed away from the brake tester
indicating the end of testing. The brake tester has two electric motors with
rated power consumption of 5.5kW each as shown in Appendix 4.2. During
the brake testing, minimal noise is generated.
·
Tyre Balancer – A tyre balancer is a piece of motorised
measurement equipment aiming to identify the shift of centre of mass of a wheel. During operation, the tyre balancer will
spin the wheel under testing and suggest the location of calibration weight to
be installed. The spinning is conducted in low speed with its motor operating at
190 rpm as shown in Appendix 4.2,
and would not generate significant noise.
The tyre balancer is thus considered to be quiet with minimal noise
generation.
·
Tyre Changer – A tyre changer is an equipment to
help the operator to remove and install the tyre from and onto the rim. It basically consists of a fixture and a
hook that will be placed between the tyre and the rim to pull the tyre from the
rim in a rotation. The motor
required for the tyre changer is also small in scale and the power consumption
is about 1.5kW as shown in Appendix 4.2,
and is thus also considered to be quiet with minimal noise generation.
·
Vehicle Cleansing Bay - The Workshop will not provide an
automatic vehicle washing bay although a vehicle cleansing bay is provided for
occasion use for cleansing in-house vehicles but the washing will be manually
undertaken. Thus operational noise
generated from cleaning is not considered.
·
Motorcycle Testing System – This
consists of a motorcycle brake tester, motorcycle speedometer calibrator and the
necessary fixtures. The motorcycle brake tester operating in
a principle similar to the roller brake tester which measures the torque of the
wheel when brake is applied. The
motorcycle engine is not required to be running and the brake tester is powered
by an electric motor with rated power consumption of 3kW as shown in Appendix 4.2. Therefore, the motorcycle brake tester
does not generate significant noise impact during operation.
With respect to the motorcycle speedometer calibrations, these tests could be a source of operational noise generated from the running motor of the system during testing. The testing of the motorcycle speedometer involves the motor turning the back wheel of the motorcycle and increasing the speed gradually from 0km/hr to 150km/hr, which will generate some noise during the testing. A noise measurement was carried out in a site visit by the representative of the manufacturer for a speedometer calibrator, AHS PRUFTECHNIK (model: Speedcheck) currently be utilised at the existing EMSD Hong Kong Workshop in Causeway Bay, and which would be used in the proposed Workshop in Chai Wan. The noise level generated during its operation was recorded at 104dB at 1m from the motor as shown in Appendix 4.2, equating to a SWL of 112dB without façade correction. There will only be one speedometer testing machine in this workshop and no more than one test per day will be conducted. The test duration would be last only about 1 minute.
·
Idling Vehicle Engines – Vehicles entering the Workshop would
require engine warm-up during maintenance.
The operational noise assessment has been undertaken based upon the
daily operations of the workshop and the predicted number of vehicles that the
workshop will be able to service. The
total estimated daily numbers of vehicles detained in the workshop has been
determined to be approximately 58, based the following vehicle categories:
- Motorcycles: 12;
- Saloon cars: 18;
- VIP and large saloon cars: 9;
- Ambulance: 4; and
- Medium sized vans: 15.
The
daily turnover rate of the above vehicles will be 15 and there will be
approximately 10 vehicles attending the workshop for a quick repair service
(which will be completed within the same day). As such, the average daily in/out
traffic volumes would equal 50 ((15 + 10) x 2) numbers of vehicles. The concurrent number of vehicles for
repairing and maintenance in the workshop is expected to be approximately 3, 5%
of the 58 vehicles, and the continuous engine on-time would be approximately 15
minutes per vehicle on the three occasions, that is, 5 minutes per vehicle per
occasion.
Due to the
short on-time and the fact that the engines are set at idle speed, the noise impact
generated would be expected to be minimal, and would not be considered as an
operational noise source.
4.5.2.4
Thus, the
key potential noise sources are considered to be limited to the noise generate
during the motorcycles speedometer tests.
Off-site Traffic Noise
4.5.2.6 As discussed in Section 4.5.2.3, the average daily in/out traffic for the Workshop is estimated to be only 50 vehicles. Therefore, within the 10 hours operation time, about 5 vehicles per hour are anticipated to enter or leave in or out of the workshop, compared with the traffic flow on Wing Tai Road of 23,000 vehicles per day in 2010.
4.6.1.1 During construction phase, there is an identified future institutional NSR which is located to the north of the Project site. It is understood, based on details obtained from the Education Bureau, that the tentative construction programme for the future tertiary institution would be a commencement of construction by the third quarter of 2013 and completion by the third quarter of 2016. In this case, construction works for the institute will be concurrent for a short period of time (probably only a few months) with the project and cumulative impacts would not be anticipated to be significant.
4.6.1.2 However, the Education Bureau has yet to identify the future operator and details of the construction works, including the schedule, plant inventory and noise impact at the NSRs, are not available for inclusion in this EIA Report. As such, details of the construction works for this institute have not been included as a concurrent project during the construction phase noise impact assessment and no cumulative construction noise impact has been determined.
4.6.1.3 In respect of the operational phase, there are two projects identified that would be relevant to the operational phase of the project, namely Citybus Depot and New World First Bus Permanent Depot.
4.6.1.4 With respective to these two existing bus maintenance depots in the study area, the respective EIA Report, the “Proposed Headquarters and Bus Maintenance Depot in Chai Wan” for Citybus (EIA 060-2001) and the “New World First Bus Permanent Depot at Chai Wan” (EIA-034/1999) (see Figure 4.2 for their respective locations), have been reviewed. The New World First Bus Permanent Depot at Chai Wan is more than 300m away from the proposed workshop (see Figure 4.2) and representative sensitive receivers and, therefore, would not constitute a concurrent noise source.
4.6.1.5 With reference to the EIA report for Citybus, operational noise impacts from the depot at NSR 2 Tsui Shou Building, Tsui Wan Estate (NSR TW-1 in the Citybus EIA Report) and NSR 4 Hong Kong Institute of Vocational Education (Chai Wan) (NSR IV-2 in the Citybus EIA Report) was predicted to be 48dB(A) and 59dB(A) respectively and the cumulative noise from this source has, therefore, been assessed.
4.7.1.1 In accordance with the EIAO-TM, the methodology outlined in the GW-TM has been used for the construction noise assessment. The general approach is summarised below:
·
Locate the NSRs which would most likely be affected by the noise from
construction works;
·
Determine the items of PME for each discrete construction activity,
based on the available information or agreed plant inventories;
·
Assign sound power levels (SWLs) to the proposed PME according to the
GW-TM or other sources;
·
Calculate the distance attenuation and screening effects to NSRs from
the notional noise source;
·
Predict the construction noise levels at NSRs in the absence of any
mitigation measures; and
·
Include a 3dB(A) façade correction to the predicted noise levels in
order to account for the façade effect at each NSR.
4.7.1.2 The SWLs of the PME have been taken from Table 3 of the GW-TM. Where no SWL is provided in the GW-TM, reference has been made to the British Standard 5228: Part 1:2009 Noise Control on Construction and Open Sites, previous similar studies or from other EIA reports or measurements taken in other relevant studies.
4.7.1.3 Groups of PME have been assigned to various construction activities of the project and the full plant inventory is presented in Appendix 4.3. The design consultant of the project has confirmed this plant inventory as being practical and adequate for completing the construction works within the scheduled timeframe. The plant inventory has been provided as one option which is considered technically feasible and represents a realistic worst-case scenario for assessment purposes in this EIA.
Workshop Noise
Broad Approach
4.7.2.1 The assessment for the operational noise impacts has been conducted based on consideration of standard acoustics principles presented in IND-TM which are summarised below:
·
Based on the preliminary design layout plans and equipment inventory
required to be provided at the new workshop, identify the key noise sources of
potential concern;
·
Estimate the sound power levels (SWL) associated with operation of each
of these activities based on the assumptions discussed in Section 4.5 and below;
·
Calculate the sound pressure levels (SPL) at selected representative
NSRs based on consideration of distance attenuation, noise shielding effect,
and façade correction; and
·
Compare the SPL with the relevant noise criteria and recommend noise
mitigation measures if necessary.
Assumed Noise Emission Levels
4.7.2.2 As discussed in Section 4.5.2, operational noise sources at the new workshop will be limited to noise from the speedometer testing machine motor, with other operational activities not being identified as potential noise sources of concern.
4.7.2.3 According to the noise measurement carried out by the manufacturer for a speedometer calibrator, AHS PRUFTECHNIK (model: AHS Speedcheck) which is currently being utilised at the existing EMSD Hong Kong Workshop in Causeway Bay, the noise generated by the noise calibrator was measured to be 104dB(A) at 1m from the motor. The SWL of the speedometer during testing have been, therefore, calculated to be 112 dB(A) for the purposes of this assessment. Since the testing duration would be about 1 minute, a 3% on-time has been assumed out of a 30 minute period for the purpose of the operational noise impact assessment.
4.7.2.4 Based upon the details in Section 4.5.2, only one test will be undertaken per day so the assessment has assumed this test would be on-going within the 30 minute assessment period.
Noise Attenuation by Permanent Structure
4.7.2.5 The equipment will be located within the workshop shed and covered by a roof. Only lower floors of nearby NSRs may be able to obtain a line of sight to the noise sources. Although the roof may offer noise attenuation to higher floors of nearby NSRs, assessed NSRs are set at lowest occupied floor and, therefore, no attenuation has been applied.
Off-site Traffic Noise
4.7.2.6 As the potential for off-site traffic noise from the relatively small number of vehicles being processed by the proposed Workshop is not expected to be significant (see Section 4.5.2.5 above), the off-site traffic noise has been assessed qualitatively by comparison with the existing traffic flows in the area.
4.7.3 Level of Uncertainty
4.7.3.1 The predictions of construction noise impacts have been based on the methodologies described in the GW-TM under the NCO. The methodologies which have previously been applied in other EIA studies is generally accepted for use in assessing construction noise impact against the EIAO-TM noise criteria. In carrying out the assessment, realistic worst case assumptions have been made in order to provide a conservative assessment of potential noise impacts. The construction noise impact has, therefore, been assessed based on conservative estimates for the types of plant to be utilised and the methods of working.
4.7.3.2 An operational noise assessment has also been carried out by identifying the noisy plant that would cause operational noise impact issues and followed a similar approach to that of the construction noise assessment. For determining the distance correction factors, exact plant location instead of notional source locations have been used to reflect a realistic scenario of the operation of the workshop.
4.7.3.3 There are some limitations in the approach, such as the accuracy of predictive base data for future conditions, for example, plant inventory for the proposed construction works and location of the fixed plant in future operation. Uncertainties in the assessment of impacts have been considered when drawing conclusions from the assessment and worst case assessments made overall.
4.8
Construction
Noise Assessment
4.8.1.1 As illustrated in the construction programme in Appendix 3.1, the different construction activities for the project would be carried out concurrently for some periods As this concurrent period presents the worst case scenario, this scenario has been used for the construction noise assessment. Based upon these concurrent activities, the unmitigated construction noise levels at representative NSRs have been predicted and summarised in Table 4.8 below. Detailed results are presented in Appendix 4.4.
Table 4.8: Predicted
Unmitigated Construction Noise Levels for Representative NSRs
|
NSR |
Name |
Maximum
Predicted Construction Noise Level, dB(A) |
EIAO
-TM Noise Criteria, dB(A) |
|
NSR 1 |
Tsui Hong House |
75 |
75 |
|
NSR 2 |
Tsui Shou House |
77 |
75 |
|
NSR 3 |
Tsui Ching House |
68 |
75 |
|
NSR 4 |
Hong Kong Institute
of Vocational Education (Chai Wan) |
67 |
70/65 |
|
NSR
5 |
Endeavourers Chan Cheng Kit Wan KG |
77 |
70 |
|
NSR
6 |
SKH Li Fook Hing Secondary School |
68 |
70/65 |
|
NSR
7 |
Chai Wan Faith Love Lutheran School |
65 |
70/65 |
Notes:
Noise
Limits of Leq(30min) for Schools is 70dB(A) for normal periods; 65dB(A) during
exam periods. There is no exam
period for NSR 5.
Numbers
in bold underline (e.g. 77) signify an exceedance of the
noise criteria.
Numbers
in italic (e.g. 67) signify an exceedance of the noise criteria during examination
periods only.
4.8.1.2 Without any mitigation applied, the noise levels at the majority of the sensitive receivers are still able to comply with the relevant noise critieria. However, in respect of Tsui Shou House, Tsui Wan Estate (NSR2) and Endeavourers Chan Cheng Kit Wan KG (NSR 5), construction noise exceedances of up to 7dB(A) would be anticipated, and noise exceedances of 2dB(A) could, also, occur during the exam periods of the Hong Kong Institute of Vocational Education (NSR4). The feasibility of providing noise reduction measures to mitigate the noise impacts has been examined and discussed below.
4.8.2.1 The results in Table 4.8 indicate that marginal construction noise impacts would be anticipated at two NSRs under the unmitigated scenario. Suitable noise mitigation measures are, therefore, required to minimise the construction noise impacts at these locations.
Quieter Plant
4.8.2.2 Quieter plant has been assumed to be applied, as presented in Appendix 4.5. The use of quieter plant (QPME) is specified for the list of equipment detailed in Table 4.9 below.
Table 4.9: Mitigated Quiet
PME
|
PME |
Reference |
SWL, dB(A) |
|
Concrete
lorry mixer |
BS
D6/33 |
96 |
|
Concrete
pump |
BS
C3/26 |
103 |
|
Dump
truck |
BS
D9/39 |
103 |
|
Tracked
excavator |
BS
C1/12 |
110 |
|
Tracked
mobile crane (132kW, 55t) |
BS
C3/29 |
98 |
4.8.2.3 The use of these QPME affords a reduction in sound power level of specific PME between 2-14dB(A).
Noise Barriers
4.8.2.4 Implementation of quieter plant alone would not be enough to bring the construction noise impact at the NSRs to an acceptable level. Temporary Noise barriers, including movable barriers and enclosure/sheds, and acoustic fabric have thus been considered, as detailed in below in Table 4.10.
Table 4.10: Mitigation Measures Adopted for PME for
Construction Works
|
PME |
Type
of Noise Barrier |
Noise
Level Reduction, dB(A) |
|
Drill
rig, rotary type (diesel) |
Acoustic Fabric |
-10 |
|
Concrete
pump |
Noise Barrier /
Enclosure |
-10 |
|
Tracked
excavator |
Temporary Noise Barrier |
-5 |
4.8.2.5 After revising the respective SWL of the PME and the total SWL of the construction works, the mitigated construction noise levels at representative NSRs have been predicted and are summarised in Table 4.11 below. Detailed results are presented in Appendix 4.6.
Table 4.11: Predicted Mitigated Construction Noise
Levels for Representative NSRs
|
NSR |
Name |
Maximum
Predicted Construction Noise Level, dB(A) |
EIAO-TM
Noise Criteria, dB(A) |
|
NSR 1 |
Tsui Hong House |
68 |
75 |
|
NSR 2 |
Tsui Shou House |
70 |
75 |
|
NSR 3 |
Tsui Ching House |
61 |
75 |
|
NSR 4 |
Hong Kong Institute
of Vocational Education (Chai Wan) |
60 |
70/65 |
|
NSR 5 |
Endeavourers Chan Cheng Kit Wan KG |
70 |
70 |
|
NSR 6 |
SKH Li Fook Hing Secondary School |
61 |
70/65 |
|
NSR
7 |
Chai Wan
Faith Love Lutheran School |
58 |
70/65 |
Notes:
Noise Limits of Leq(30min) for
Schools is 70dB(A) for normal periods; 65dB(A) during exam periods. There is no exam period for NSR 5.
4.8.2.6 With the implementation of quieter plant and appropriate temporary noise barriers, the predicted construction noise levels are predicted to be below the EIAO acceptable criteria. Thus, it is anticipated that the construction works would not cause unacceptable noise impacts to the nearby NSRs.
4.8.2.7 However, in addition to the specified mitigation measures listed above, there are, also, some good site practices that would be recommended to be applied to further reduce the noise levels at NSRs. However, these are non-quantifiable and, thus, not included in the noise level calculations. These include:
·
Only well-maintained plant should be operated on-site and plants should
be serviced regularly during the construction period;
·
Mobile plant, if any, should be sited as far from NSRs as possible;
·
Plant known to emit noise strongly in one direction should, wherever
possible, be properly orientated so that the noise is directed away from the
nearby NSRs;
·
Use of site hoarding as a noise barrier to screen noise at low level
NSRs;
·
Machines and plant that may be in intermittent use should be shut down
between works periods or should be throttled down to a minimum; and
·
Any material stockpiles and other structures should be effectively
utilised, wherever practicable, to screen the noise from on-site construction
activities.
4.9
Operational
Noise Assessment
Assessment Results
4.9.1.1 During the operational phase, the noise impact induced by the identified noise source has been assessed. Based upon the assumptions discussed in Section 4.5.2, the operational noise levels at representative NSRs are summarised in Table 4.12 below. Detailed results are presented in Appendix 4.7.
Table 4.12: Operational noise Levels for
Representative NSRs
|
NSR |
Name |
Maximum
Predicted Noise Level, dB(A) |
ASR
Rating |
EIAO
-TM Noise Criteria, Leq 30min, dB(A) |
|
NSR 1 |
Tsui Hong House |
52 |
C |
65 |
|
NSR 2 |
Tsui Shou House |
54 |
C |
65 |
|
NSR 3 |
Tsui Ching House |
46 |
C |
65 |
|
NSR 4 |
Hong Kong Institute
of Vocational Education (Chai Wan) |
44 |
C |
65 |
|
NSR
5 |
Endeavourers Chan Cheng Kit Wan KG |
54 |
C |
65 |
|
NSR
6 |
SKH Li Fook Hing Secondary School |
46 |
C |
65 |
|
NSR
7 |
Chai Wan Faith Love Lutheran School |
43 |
C |
65 |
|
NSR 8 |
Planned
Educational Institute |
68 |
C |
65 |
Notes:
Numbers
in bold underline (e.g. 77) signify the exceedance of
the noise criteria.
4.9.1.2 It is noted that exceedances is anticipated at NSR 8 due to insufficient separation distance between the NSR and the noise source. A noise barrier is, therefore, recommended to be installed to screen the speedometer and mitigate the 3 dB(A) exceedance.
4.9.1.3 A common plywood board with noise absorbent lining facing the speedometer is anticipated to be sufficient to provide a noise attenuation of 5dB(A). While the exact layout of the future NSR is yet to be known, the roof top of the workshop is about 6.5m high and thus protecting the façade above 6.5m of NSR 8. Therefore, a noise barrier would be required to protect the façade from ground floor to 6.5m of NSR 8.
4.9.1.4 As such, a 1 m high noise barrier installed at the speedometer calibrator, together with the screening effect of the roof of this Workshop at approximately 6.5m above ground, would be enough to protect NSR 8 considering the noise barrier is placed about 1.5 m from the motor of the speedometer calibrator. In addition, there is the possibility of noise from the speedometer calibrator being reflected from the metal roof towards NSR8. To mitigate the potential reflected noise, an additional noise barrier in form of a noise curtain hanging from the supporting frame at the western site boundary (which serves a dual purpose to also screen off the operational activities of the workshop such that the maintenance activities will not be visible to the users of the proposed educational institute as addressed in Section 8 of this EIA Report) will be provided. The arrangement of these mitigation measures is illustrated in Figure 4.5 which shows the cross-section between the motorcycle speedometer calibrator and NSR 8. It should be noted that the implementation of this mitigation would be applicable only when NSR 8 Planned Educational Institute is operational.
4.9.1.5 After taking into account the attenuation of the noise barrier, the mitigated operational noise level at NSR 8 has been predicted and is summarised in Table 4.11 below. Detailed results are presented in Appendix 4.8.
Table 4.13: Operational
noise Levels for NSR8
|
NSR |
Name |
Maximum
Predicted Noise Level, dB(A) |
ASR
Rating |
EIAO-TM
Noise Criteria, Leq 30min, dB(A) |
|
NSR 8 |
Planned
Educational Institute |
63 |
C |
65 |
4.9.1.6 The operational noise impacts at the representative NSRs are, thus, below the EIAO acceptable criteria after mitigation measures have been implemented. Thus, it is anticipated that the project would not cause unacceptable operational noise impacts to the nearby NSRs.
4.9.1.7 It should be noted that since NSR 8 is not yet operational, the above mentioned mitigation measures would not be implemented during the construction phase of the project until NSR 8 is in its operation phase.
4.9.1.8 For NSR 8 the Planned Educational Institute, it should, also, be noted that this future NSR may be exposed to operational noise impact lower than the predicted level due to the following reasons:
·
The NSR would likely be equipped with central air conditioning system
that does not rely on open windows for ventilation;
·
The construction details, including the layout plan, of SR8 is yet to be
confirmed. The NSR is, therefore,
assumed to be located at the site boundary facing the speedometer calibrator
for the worst case scenario. The
NSR would likely to have a set back distance between the lecture rooms and the
boundary and fenced off with its own boundary walls, and thus move the NSRs
further away from the noise source; and
·
The proposed NSR 8 may allocate noise tolerance uses of the project,
e.g. plant rooms, next to the Workshop, and, thus, eliminate the need of
mitigation.
4.9.1.9 Thus, the mitigation measures for the speedometer calibrator would be reviewed and revised subject to further liaison with Educational Bureau regarding the architectural design of the proposed institutional NSR.
Cumulative Impacts
4.9.1.10 The EIA report for the Citybus bus maintenance depot, also, assessed its operational noise impact to nearby NSRs. Only NSR 2 Tsui Shou House and NSR 4 HKIVE (Chai Wan), which are common to this EIA, were assessed by Citybus and it was concluded that a noise level of 48dB(A) and 59dB(A) would result at these NSRs respectively as a result of the Citybus depot operations. The above two concurrent activities have been assessed in conjunction with the proposed EMSD Hong Kong Workshop to provide cumulative impacts at NSR 2 and NSR 4 only.
4.9.1.11 Cumulative impacts have been assessed using the same approach as detailed above. The notional sources are shown in Figure 4.4 and the cumulative operational noise levels at representative NSRs are summarised in Table 4.14 below. Detailed results are presented in Appendices 4.7-4.8.
Table 4.14: Predicted Cumulative Operational
Noise Levels for Representative NSRs
|
NSR |
Name |
Maximum Predicted Noise Level, dB(A) |
ASR Rating |
EIAO -TM Noise Criteria, Leq 30min, dB(A) |
|
NSR
1 |
Tsui
Hong House |
52 |
C |
65 |
|
NSR
2 |
Tsui
Shou House |
55 |
C |
65 |
|
NSR
3 |
Tsui
Ching House |
46 |
C |
65 |
|
NSR
4 |
Hong
Kong Institute of Vocational Education (Chai Wan) |
59 |
C |
65 |
|
NSR
5 |
Endeavourers
Chan Cheng Kit Wan KG |
55 |
C |
65 |
|
NSR
6 |
SKH
Li Fook Hing Secondary School |
46 |
C |
65 |
|
NSR
7 |
Chai
Wan Faith Love Lutheran School |
43 |
C |
65 |
|
NSR 8 |
Planned Educational Institute |
63 |
C |
65 |
4.9.1.12 The predicted cumulative operational noise levels are shown to be higher then the EMSD Hong Kong Workshop alone but the noise levels are still below the EIAO acceptable criteria. Thus, it is anticipated that the operation of the workshop, in association with the concurrent activities in the area, would not cause unacceptable operational phase noise impacts to the nearby NSRs.
4.9.2
Off-site Traffic Noise
4.9.2.1 As discussed in Section 4.5.2.3, the average daily in/out traffic is estimated to be only 50 vehicles, resulting from a capacity of 58 vehicles and a daily turnover rate of 15 vehicles, in addition to 10 vehicles attending the workshop for a quick repair service and be completed within the same day. Therefore, within the 10 hours operation time, about 5 vehicles per hours is anticipated to go in or out of the workshop.
4.9.2.2 The nearest road to the Workshop is Wing Tai Road. Traffic data released by the Transport Department showed that the AADT at Wing Tai Road is about 23,000 in 2010. It is considered that the traffic on Wing Tai Road represents the dominant traffic noise for NSRs within close proximity to the site. However, the increased traffic will only make up to about 0.2% of the daily traffic and approximately 0.5% hourly.
4.9.2.3 The traffic increase as a result of the project is, thus, considered small and would not lead to any significant increase in traffic noise impact at the NSRs.
4.9.3 Mitigation Measures
4.9.3.1 The predicted workshop operational noise levels are below the EIAO acceptable criteria except at NSR 8. A noise barrier of 1 m high is therefore recommended to be installed at the speedometer calibrator to mitigate the noise impact at the future institutional NSR. It should be noted that the implementation of this mitigation would be applicable only when NSR 8 Planned Educational Institute is in place of operation.
4.9.3.2 Off-site impacts associated with increased traffic noise from the vehicles using the Workshop are, not expected and no mitigation has been recommended.
4.10.1.1 With the implementation of the mitigation measures in the form of utilizing quieter plant and temporary noise barrier, adverse impacts would not be anticipated during the construction phase. Thus, there would be no adverse residual impact anticipated at nearby NSRs.
4.10.1.2 In respect to operational phase noise assessment, with proper noise barrier installed at the speedometer calibrator and noise curtain at the western site boundary, there would be no adverse residual impacts anticipated at nearby NSRs even though the operation would be extended beyond July 2017 as planned.
4.11
Environmental
Monitoring and Audit
4.11.1.1 The assessment has concluded that, with the implementation of the mitigation measures in the form of utilising quieter plant only, no adverse residual impacts would be anticipated during the construction phase. However, it is recommended that construction phase environmental monitoring and audit (EM&A) at NSR2 and NSR4 is undertaken to ensure that adverse impacts do not occur. No EM&A for the operational phase is recommended. Further details of the specific EM&A requirements are detailed in Section 10 of this report and in the EM&A Manual, together with event action plans and procedures for complaints.
4.12.1.1
With the use of quieter construction
plant and noise barrier, adverse impact to the NSRs would not be anticipated
during the construction phase. In
the operational phase, with proper noise barrier is installed at the noise
equipment, adverse impacts would also not be anticipated, even though the
operation would be extended beyond July 2017 as planned.