天 水 圍 預 留 區 輕 鐵 支 線 及
屯 門 杯 渡 路 青 麟 路 之 輕 鐵 架 空 路 軌
1.1 EIA Study Brief
1.2 Background Information
1.3 Previous Studies and Environmental Benefits
1.4 Structure of EIA Report
2.1 Alignment
2.2 Neighbouring Environment
2.3 LR Operations
2.4 Preliminary Construction Programme
2.5 Cumulative Impacts
3.1 Study Objectives
3.2 Study Scope
4 AVAILABLE TECHNICAL Information
5.1 Legislation and Standards
5.1.1... Hong Kong Air Pollution Control Ordinance
5.1.2... Air Pollution Control (Construction Dust) Regulation
5.2 Major Construction Activities
5.3 Recommendations
5.4 Conclusion
6 Operational Noise Assessment
6.1 Legislation and Standards
6.1.1... Railway Noise Criteria – Airborne Noise
6.1.2... Fixed Plant Noise Criteria
6.2 Noise Sensitive Receivers (NSRs)
6.2.1... NSR Locations
6.2.2... Area Sensitivity Ratings
6.3 Airborne Noise Assessment
6.3.1... Assessment Methodology
6.3.1.1..... Train Noise Data and Operational Data
6.3.1.2..... Correction for Rail Deterioration
6.3.1.3..... Correction for Train Speeds
6.3.1.4..... Correction for Distance
6.3.1.5..... Correction for Deck Reflection
6.3.1.6..... Correction for Joints
6.3.1.7..... Wheel Squeal
6.3.1.8..... Conversion to SEL
6.3.1.9..... Correction for Train Frequency
6.3.1.10... View Angle
6.3.1.11... Correction for Façade Reflection
6.3.1.12... Cumulative Noise Impacts from West Rail
6.3.1.13... Structure Re-radiated Noise from Viaduct Structure
6.3.1.14... Normal, Abnormal and Emergency Operation
6.3.2... Assessment Results
6.4 Fixed Plant Noise Assessment
6.4.1... Noise Sources
6.4.2... Assessment Methodology
6.4.3... Assessment Results
6.4.3.1..... Transformer Noise
6.4.3.2..... Other Noise Sources
6.5 Recommendations
6.6 Conclusion
7 Construction Noise Assessment
7.1 Legislation and Standards
7.1.1... Noise Standards in Normal Working Hours
7.1.2... Noise Standards in Restricted Hours
7.2 Assessment Methodology
7.2.1... Noise Prediction Methodology
7.2.2... Noise Mitigation Strategy
7.2.2.1..... M1: Level One Mitigation Measures
7.2.2.2..... M2: Level Two Mitigation Measures
7.2.2.3..... M3: Level Three Mitigation Measures
7.2.2.4..... M4: Level Four Mitigation Measures
7.3 Construction Noise Assessment
7.3.1... Noise Sensitive Receivers
7.3.2... Potential Sources of Impacts
7.3.3... Cumulative Construction Noise Impact with West Rail Construction
7.3.4... Predictions of Impacts
7.3.5... Evaluation of Impacts
7.3.5.1..... Pui To Road Grade Separation
7.3.5.2..... LT1 Grade Separation
7.3.5.3..... Tin Shui Wai Reserve Zone Extension
7.3.6... Recommended Mitigation Measures
7.3.6.1..... Good Site Practices and Noise Management Techniques
7.3.6.2..... Scheduling of Construction Works Outside School Examination Period
7.3.6.3..... Use of “Quiet” Equipment and Working Methods (M1)
7.3.6.4..... Purpose Built Temporary Noise Barriers (M2)
7.3.6.5..... Movable Noise Barriers (M2)
7.3.6.6..... Delocalization of Equipment in Critical Areas (M3)
7.3.6.7..... Local Reduction of Number of Plant Operating in Critical Areas where Practicable (M3)
7.3.6.8..... Limiting Operation Time of Construction Equipment On-Site (M4)
7.3.7... Prediction of Mitigated Noise Levels
7.3.7.1..... Pui To Road Grade Separation
7.3.7.2..... LT1 Grade Separation
7.3.7.3..... Tin Shui Wai Reserve Zone Extension
7.3.7.4..... Cumulative Impacts Within LRT Worksites
7.3.8... Further Mitigation to be Considered by the Contractor
7.4 Conclusion
8.1 Legislation and Standards
8.1.1... Water Pollution Control Ordinance (WPCO)
8.1.2... Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters
8.1.3... The Deep Bay “Zero Discharge Policy”
8.1.4... Construction Site Drainage Guidelines
8.2 Assessment Methodology
8.2.1... Construction Phase
8.2.2... Operational Phase
8.3 Assessment Results
8.3.1... Construction Phase
8.3.1.1..... Water Sensitive Receivers (WSRs)
8.3.1.2..... Baseline Conditions
8.3.1.3..... Potential Source of Impact
8.3.1.4..... Prediction and Evaluation of Impact
8.3.2... Operation Phase
8.3.2.1..... Baseline Conditions
8.3.2.2..... Potential Sources of Impacts
8.3.2.3..... Predication and Evaluation of Impacts
8.4 Recommendations
8.4.1... Construction Phase
8.4.1.1..... Construction Runoff
8.4.1.2..... Sewage Effluent
8.4.1.3..... Residual Impacts
8.4.2... Operation Phase
8.4.2.1..... Runoff from Rail Track
8.4.2.2..... Residual Impacts
8.5 Conclusion
9 Waste Management Implications
9.1 Legislation and Standards
9.2 Assessment Methodology
9.2.1... Types and Nature of Waste Generated
9.2.1.1..... Construction Phase
9.2.1.2..... Operational Phase
9.2.2... Proposed Waste Management Methods
9.3 Assessment Results
9.3.1... Potential Sources and Prediction of Impacts
9.3.1.1..... Construction Phase
9.3.1.2..... Operational Phase
9.3.2... Evaluation of Impacts
9.3.2.1..... Construction Phase
9.3.2.2..... Operational Phase
9.4 Recommendations
9.4.1... Construction Phase
9.4.1.1..... Waste Management Hierarchy
9.4.1.2..... Storage, Collection and Transport of Waste
9.4.1.3..... Excavated Material
9.4.1.4..... Construction and Demolition Material
9.4.1.5..... Chemical Waste
9.4.1.6..... General Refuse
9.4.2... Operational Phase
9.4.2.1..... General Refuse and Industrial Waste
9.4.2.2..... Chemical Waste
9.5 Conclusion
10 Cultural Heritage Assessment
10.1 Legislation and Standards
10.2 Assessment Methodology
10.2.1. Relevant Information from West Rail Project
10.2.2. Liaison with AMO
10.2.3. Field Evaluation
10.3 Assessment Results
10.3.1. Tin Shui Wai Reserve Zone Extension
10.3.2. Grade Separation of Junction LT1
10.3.3. Grade Separation of Junctions J6, Mj7 and Mj8
10.4 Recommendations
10.5 Conclusion
11 Landscape and Visual Impacts
11.1 Legislation and Standards
11.2 Landscape Impact Assessment Methodology
11.3 Visual Impact Assessment Methodology
11.4 Mitigation Measures
11.5 Residual Impacts
11.6 Review of Planning and Development Control Framework
11.7 Assessment Results for Tin Shui Wai Reserve Zone
11.7.1. Existing Landscape and Visual Context
11.7.2. Impacts
11.7.3. Recommended Mitigation Measures During Construction / Operation
11.8 Assessment Results for Grade Separation for Tsing Lun Road, Tuen Mun
11.8.1. Existing Landscape and Visual Context
11.8.2. Impacts
11.8.3. Recommended Mitigation Measures During Construction / Operation
11.9 Assessment Results for Grade Separation At Pui To Road, Tuen Mun
11.9.1. Existing Landscape and Visual Context
11.9.2. Impacts
11.9.3. Recommended mitigation measures during construction/operation
11.10 Funding, Implementation, Management and Maintenance
11.11 Summary of Landscape Impacts
11.12 Conclusions
12 environmental monitoring and auditing programme
12.1 EM&A Manual for EIA Study
12.2 Amendments to EM&A Manual
12.3 Implementation Schedule
12.4 Environmental Management Plans (EMP)
13 recommendations and conclusions
14 Summary of Environmental Outcomes
16 references
APPENDICES
Appendix 1 Layout of
Proposed LRT Works
Appendix 2 Locations and
Description of Representative Noise Sensitive Receivers
Appendix 3 Building Plans
for Tin Shui Wai Reserve Zone (Provided by HKHA)
Appendix 4 Predicted Train
Frequency and Speed (Provided by KCR)
Appendix 5 Updated Noise
Calculations for West Rail (for 12-car trains)
Appendix 6 Normal, Abnormal
and Emergency Operations for LRT
Appendix 7 Predicted
Cumulative Train Noise Impacts
Appendix 8 Not Used
Appendix 9 Fixed Plant
Noise Assessment
Appendix 10 Separation Distance of NSRs
to Construction Sites
Appendix 11 Construction Plant
Inventory & Construction Schedule
Appendix 12 Sound Power Level of
Quiet Equipment
Appendix 13 List of Declared and
Deemed Monuments
Appendix 14 Photos Taken During Field
Evaluation
Appendix 15 Letter from TDD
FIGURES
Figure 2.1 Location
Plan
Figure 2.2a Layout
of Proposed LRT Works (Tin Shui Wai Reserve Zone)
Figure 2.2b Layout
of Proposed LRT Works (Pui To Road, Tuen Mun)
Figure 2.2c Layout
of Proposed LRT Works (Lam Tei)
Figure 6.1 Maximum
Structure Reradiated Noise from Existing LRT Viaduct Near MJ9
Figure 8.1 Location
of Water Sensitive Receivers and Monitoring Locations (Tin Shui Wai Area)
Figure 8.2 Location
of Water Sensitive Receivers and Monitoring Locations (Tuen Mun River)
Figure 8.3 Location
of Water Sensitive Receivers and Monitoring Locations (Tuen Mun Typhoon Shelter
and Gazaetted Beach)
Figure 11.1 Tin
Shui Wai Reserve Zone LRT Extension Landscape Impact Assessment Survey Plan
Figure 11.2 Typical
views of Landscape character units within Tin Shui Wai Reserve Zone
Figure 11.3 Tin
Shui Wai Reserve Zone LRT Extension Visual Impact Assessment Survey Plan
Figure 11.4 Tin
Shui Wai Reserve Zone LRT Extension Illustrative views of Landscape mitigation
measures
Figure 11.5 Tin
Shui Wai Reserve Zone LRT Extension Illustrative views of Landscape mitigation
measures
Figure 11.6 Tin
Shui Wai Reserve Zone LRT Extension Illustrative views of Landscape mitigation
measures
Figure 11.7 Tin
Shui Wai Reserve Zone LRT Extension Illustrative views of Landscape mitigation
measures
Figure 11.8 Tin
Shui Wai Reserve Zone LRT Extension Illustrative views of Landscape mitigation
measures
Figure 11.9 Grade
Separation of LRT at Tsing Lun Road, Tuen Mun Landscape Impact Assessment
Survey Plan
Figure 11.10 Typical
views of Landscape character units within Tsing Lun Road Area
Figure 11.11 Grade
Separation of LRT at Tsing Lun Road, Tuen Mun Visual Impact Assessment Survey Plan
Figure 11.12 Lam
Tei LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.13 Lam
Tei LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.14 Lam
Tei LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.15 Grade
separation of LRT at Pui To Road, Tuen Mun Landscape Impact Assessment Survey
Plan
Figure 11.16 Typical
views of Landscape character units within Pui To Road, Tuen Mun
Figure 11.17 Typical
views of Landscape character units within Pui To Road, Tuen Mun
Figure 11.18 Grade
Separation of LRT at Pui To Road, Tuen Mun Visual Impact Assessment Survey Plan
Figure 11.19 Pui
To Road LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.20 Pui
To Road LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.21 Pui
To Road LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.22 Pui
To Road LRT Extension Illustrative views of Landscape mitigation measures
Figure 11.23 Pui
To Road LRT Extension Illustrative views of Landscape mitigation measures
ABBREVIATIONS
|
AAB |
Antiquities Advisory Board |
|
AMO |
Antiquities and Monuments Office |
|
ANL |
Acceptable Noise Levels |
|
APCO |
Air Pollution Control Ordinance |
|
AQO |
Air Quality Objectives |
|
ASR |
Area Sensitivity Ratings |
|
BNL |
Basic Noise Levels |
|
BOD5 |
5-day Biochemical Oxygen Demand |
|
CNP |
Construction Noise Permit |
|
COD |
Chemical Oxygen Demand |
|
CRN |
Calculation of Rail Noise |
|
CRTN |
Calculation of Road Traffic Noise |
|
DB |
Decibels |
|
DDC |
Detailed Design Consultant |
|
DO |
Dissolved Oxygen |
|
DPA |
Development Permission Area |
|
EIA |
Environmental Impact Assessment |
|
EIAO |
Environmental Impact Assessment Ordinance |
|
EM&A |
Environmental Monitoring and Auditing |
|
EPD |
Environmental Protection Department |
|
FMC |
Fill Management Committee |
|
HKAQO |
Hong Kong Air Quality Objectives |
|
HKHA |
Hong Kong Housing Authority |
|
HKPSG |
Hong Kong Planning Standards and Guidelines |
|
Hz |
Hertz |
|
KCR/KCRC |
Kowloon-Canton Railway Corporation |
|
LR/LRT |
Light Rail |
|
NCO |
Noise Control Ordinance |
|
NSR |
Noise Sensitive Receiver |
|
OZP |
Outline Zoning Plan |
|
PCW |
Prescribed Construction Work |
|
PME |
Powered Mechanical Equipment |
|
ppm |
Parts per Million |
|
ProPECC |
Professional Persons Environmental Consultative Committee |
|
PS |
Particular Specification |
|
PTI |
Public Transport Interchange |
|
RSP |
Respirable Suspended Particulates |
|
SEL |
Sound Exposure Level |
|
SPME |
Specified Powered Mechanical Equipment |
|
SS |
Suspended Solids |
|
SSC |
Suspended Sediment Concentration |
|
SWL |
Sound Power Level |
|
TIS |
Tin Shui Wai |
|
TM |
Technical Memorandum |
|
TOC |
Total Organic Carbon |
|
TSP |
Total Suspended Particulates |
|
VSR |
Visually Sensitive Receivers |
|
WBTC |
Works Branch Technical Circular |
|
WCO |
Water Control Objectives |
|
WCZ |
Water Control Zone |
|
WDO |
Water Disposal Ordinance |
|
WPCO |
Water Pollution Control Ordinance |
|
WQO |
Water Quality Objectives |
|
WR |
West Rail |
|
WSR |
Water Sensitive Receivers |
Ove Arup & Partners (OAP) was commissioned by Kowloon Canton Railway Corporation (KCRC) as the EIA Consultant for the Light Rail Transit (LRT) works for Tin Shui Wai Reserve Zone and Grade Separation of the LRT with Pui To Road and Tsing Lun Road in Tuen Lun.
An application (No ESB-27/1999) for an EIA study brief under Section 5(1) of the Environmental Impact Assessment Ordinance (EIAO) was submitted by KCR on 19 October 1998 with a project profile (No. PP-040/1999). The project profile covers a designated project under the EIAO by virtue of the Section A.2 of the Schedule 2, Part 1 of the EIAO. Pursuant to Section 5(7)(a) of EIAO, EPD issued a study brief (ref: EIA Study Brief No: ESB-027/1999) [1] to KCR to conduct the necessary EIA study.
The existing Light Rail (LR) system was introduced to serve residents of Tuen Mun and Yuen Long in September 1988 with an initial network of 24km, 6 routes and 41 stops. To cater for the continual development and population growth of the Northwest New Territories, the LR had further expanded in Tuen Mun and Tin Shui Wai in stages since early 1990s. In March 1995, Phase 3 of Tin Shui Wai Extension, the last portion of the existing LR extension works, was put into passenger service. The whole LR network now comprises 32 km of double track, 8 routes and 57 stops. The average daily patronage in 1998 was 350,000, including 37,000 on LR feeder bus.
The existing LR network will be expanded to meet the increasing travel demand due to the introduction of the West Rail (WR). In addition to the current role of internal public transport, LR will also provide major feeder transport service to WR passengers at four WR stations, namely, Yuen Long, Tin Shui Wai, Siu Hong and Tuen Mun. It is therefore important to develop integrated design solutions at WR/LR interchanges in order to ensure the pedestrian linkages are safe, efficient and user friendly to the passengers. Tin Shui Wai Phase 4 Extension and Tin Shui Wai Reserve Zone Extension will also be built to improve the accessibility of WR in the eastern and northern parts of Tin Shui Wai.
A section of the existing LR tracks running at-grade along Pui To Road in Tuen Mun, and another section that crosses the Tsing Lun Road at-grade junction in northern part of Tuen Mun will be elevated. The signalling system for the operation of the LR vehicles will be replaced by a new system in the new extensions, and subsequent replacement to the entire LR system.
The provision for LRT in the Tin Shui Wai Reserve Zone was initiated in the previous engineering investigation study for Tin Shui Wai and Reserve Zone [22] in 1997. The engineering feasibility for the LRT alignment and associated facilities (stops, rectifier stations and terminus) have been endorsed.
The
introduction of the proposed LRT extension in Tin Shui Wai Reserve Zone would
provide an efficient and direct connection with the West Rail Tin Shui Wai
Station. According to the OZP S/TSW/3
dated 1998 for Tin Shui Wai Area, there would be about 129,000 population in
the Tin Shui Wai reserve zone.
The entire population will be benefited from the introduction of the
proposed LRT, especially for the connection with West Rail network.
The structure of this EIA report is outlined below for easy reference:
|
Section |
Title |
Aims |
|
1 |
Introduction |
An introduction of the
background information and the layout of the EIA report |
|
2 |
Project Description |
A description of the extent
and details of the project available |
|
3 |
Study Objectives and Scope |
Outline the objectives and
scope for various environmental aspects |
|
4 |
Available Technical
Information |
List the key information
reviewed in this EIA study |
|
5 |
Air Quality Assessment |
Present the legislation,
methodology and recommendations for air quality impacts during construction
phase |
|
6 |
Operational Noise
Assessment |
Present the legislation,
methodology and recommendations for operational noise impacts |
|
7 |
Construction Noise
Assessment |
Present the legislation,
methodology and recommendations for construction noise impacts |
|
8 |
Water Quality Assessment |
Present the legislation,
methodology and recommendations for water quality impacts |
|
9 |
Waste Management
Implications |
Present the legislation,
methodology and recommendations for waste management |
|
10 |
Cultural Heritage
Assessment |
Present the legislation,
methodology and recommendations for cultural heritage |
|
11 |
Landscape and Visual
Impacts |
Present the legislation,
methodology and recommendations for landscape and visual impacts |
|
12 |
Environmental Monitoring
and Auditing Programme |
Present the legislation,
methodology and recommendations for EM&A |
|
13 |
Recommendations and
Conclusions |
Summary of the findings
and recommendations |
|
14 |
Summary of Environmental
Outcomes |
Summarise environmental
outcomes and benefits |
|
15 |
Implementation Schedule |
Summarise implementation
responsibility for environmental mitigation measures |
|
16 |
References |
List of relevant reference
information |
The proposed light railway extension and alteration works are located in Tin Shui Wai and Tuen Mun (Figure 2.1). The light railway in Tin Shui Wai Reserve Zone lies within the formed LRT reserve and is approximately 2.6km long and has 6 stops. The track will be on ballast and at grade for all the sections.
The grade separation work in Pui To Road and Lam Tei involves elevating the existing trackworks near Junctions J6, Mj7, Mj8 and LT1. The future horizontal alignment would generally follow the existing alignment. For the viaduct at LT1, a safety enclosure will be provided for the entire viaduct and paved track would be employed due to the constraints imposed by the overhead electricity power lines. Temporary track diversion will be located directly to the west of the existing track. The temporary track will be on ballast and at grade.
For the viaduct section in Pui To Road Grade Separation, a composite structure consisting of a concrete deck supported by steel portals will be adopted. All the steel elements of the portals will be encased in concrete. Except for the track directly underneath the deck of the future West Rail Tuen Mun Station, ballast track will be employed.
Temporary track diversion in Pui To Road will be close to the existing track. All steel elements of the temporary structure will also be encased in concrete.
Figure 2.2a to 2.2c show the layout of the proposed LRT works. Detailed drawings of the layout are given in Appendix 1.
The developments alongside the proposed alignment have been completed. These developments include the following:
|
Area |
Developments
along alignment |
|
Reserve Zone |
· Residential areas and Government / Institution / Community |
|
Pui To Road |
· Residential areas and Schools |
|
Tsing Lun Road |
· Residential areas |
Table 2.1 : Summary
of Developments Along Alignment
All the existing residential premises are with openable windows. Some of the schools are provided with air conditioning. A detailed description of these developments is given in Appendix 2.
The normal operating period of the proposed LRT would be from 0530 to 0130 hours. As advised by LR, the AM peak would start from 0630 hours in the morning. The train frequency during PM peak would be lower than the frequency during AM peak.
It is planned to
start the construction work by early 2001. The construction period would last for approximately 3
years. A tentative construction
programme is given in Appendix 11.
This assessment
has taken into account the cumulative impacts (both during operational and
construction phases) from West Rail.
In accordance
with the current construction schedules of LRT and West Rail, the two projects
have no over-lapping construction period except that the LRT site formation
work at Pui To Road (ie LRT Tuen Mun Station and San Fat LR Stop) would be
overlapping with beam erection and station construction of West Rail. This arrangement has been taken into
account in the assessment.
The objectives of this EIA study are:
a) To describe the proposed project and associated works together with the requirements for carrying out the proposed project;
b) To identify and describe the elements of the community and environment likely to be affected by the proposed and / or likely to cause adverse impacts to the proposed project, including both the natural and man-made environment.
c) To identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;
d) To identify any negative impacts on sites of cultural heritage and to proposed measures to mitigate these impacts;
e) To identify any potential landscape and visual impacts and to propose measures to mitigate these impacts;
f) To propose the provision of infrastructure or mitigation measures so as to minimise pollution, environmental disturbance and nuisance during construction and operation of the project;
g) To identify, predict and evaluate the residual (ie after practicable mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operational phases of the project in relation to the sensitive receivers and potential affected uses;
h) To identify, assesses and specify methods, measures and standards, to be included in the detailed design, construction and operation of the project which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;
i) To investigate the extent of side-effects of proposed mitigation measures that may lead to other forms of impacts;
j) To identify constraints associated with the mitigation measures recommended in the EIA study;
k) To design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.
l) The objectives of the EIA study are to describe the proposed LRT works and identify elements of the community and environment likely to be adversely affected. The landscape and visual component of the EIA will identify any potential landscape and visual impacts during construction and upon completion, assess the scale and severity of such impacts and propose mitigation measures.
According to the study brief [1], the EIA study shall address the following aspects:
a) Air quality impact;
b) Noise impact;
c) Water quality impact;
d) Waste management implications;
e) Impact on cultural heritage;
f) Landscape and visual impact; and
g) Environmental Monitoring and Audit (EM&A) requirements.
A summary of the key information reviewed in this study is given below:
|
Description |
Date |
|
Final Assessment Report, West Kowloon to Tuen Mun Centre, Contract
No. TS-900 Environmental Impact Assessment Report |
Feb 1999 |
|
Final Assessment Report, Technical Annexes, Contract No. TS-900,
Environmental Impact Assessment |
Feb 1999 |
|
Environmental Monitoring and Audit Manual, West Kowloon to Tuen Mun
Centre, Contract TS-900, Environmental Impact Assessment |
Sept 1998 |
|
Archaeological Action Plan, Contract DD901, Environmental Support
Services |
Feb 1999 |
|
Essential Public Infrastructure Works, Final EIA Report, Contract No.
DD-901, Environmental Support Services |
May 1999 |
|
Supplement to the Archaeological Action Plan, The Au Tau Area,
Contract No DD-901, Environmental Support Services |
May 1999 |
|
Agreement No CE 66/96, Planning and Development Study on North West
New Territories, Environmental Assessment, Technical Paper No. 6, Report No.
0208/TEC/T6.1 |
Apr 1999 |
|
Agreement No CE 10/95, Tin Shui Wai Development, Engineering
Investigations for Development of Areas 3, 30 & 31 of the Development
Zone and the Reserve Zone, Final Investigation Report, Vol 1 - Main Text,
Executive Summary, EIA |
Mar 1997 |
|
Agreement No CE 12/97, Tin Shui Wai Further Development, Design and
Construction – Intensification of Areas 104 and 108b, Feasibility Assessment
on Noise, Air Quality and Solid Waste Impacts, 0188/ENG/R6.2 |
Jun 1998 |
|
Agreement No CE 12/97, Tin Shui Wai Further Development,
Intensification of Areas 104 and 108b, Final Report on Sewerage Impact
Assessment, 0188/ENG/R4.2 |
Jun 1998 |
|
Agreement No CE 12/97, Tin Shui Wai Further Development,
Intensification of Areas 104 and 108b, Final Report on Traffic Impact
Assessment, 0188/ENG/R5.2 |
Jun 1998 |
|
Lam Tei & Yick Yuen - Outline Zoning Plan, S/TM-LTYY/1 |
Jun 1996 |
|
Tuen Mun - Outline Zoning Plan, S/TM/11 |
Jan 1999 |
Table 4.1 : Summary of Available Key Information
The Air Pollution Control Ordinance (APCO) [3] requires that the impacts from all air pollutant emissions from industrial activities and other sources to comply with the Hong Kong Air Quality Objectives (HKAQO). The HKAQO stipulates a set of air quality objectives for 7 common air pollutants. The following table summarises the HKAQO.
|
|
Concentration in
micrograms per cubic metre (i) |
||||
|
Pollutant |
1
Hour (ii) |
8
Hour (iii) |
24
Hours (iii) |
3
Months (iv) |
1
Year (iv) |
|
Sulphur Dioxide |
800 |
|
350 |
|
80 |
|
Total Suspended Particulates |
500 |
|
260 |
|
80 |
|
Respirable Suspended Particulates (v) |
|
|
180 |
|
55 |
|
Carbon Monoxide |
30,000 |
10,000 |
|
|
|
|
Nitrogen Dioxide |
300 |
|
150 |
|
80 |
|
Photochemical Oxidants (as ozone) (vi) |
240 |
|
|
|
|
|
Lead |
|
|
|
1.5 |
|
Table 5.1: Hong Kong Air Quality Objectives
Notes: (i) Measured
at 298K(25 oC) and 101.325 kPa (one atmosphere).
(ii) Not
to be exceeded more than three times per year.
(iii) Not
to be exceeded more than once per year.
(iv) Yearly
and three monthly figures calculated as arithmetic means.
(v) Respirable
suspended particulates means suspended particles in air with nominal
aerodynamic diameter of 10 micrometres and smaller.
(vi) Photochemical
oxidants are determined by measurement of ozone only.
This regulation [4] stipulates the construction dust control requirements for both Notifiable (eg site formation) and Regulatory (eg road opening) Works to be carried out by the Contractor. The requirements for various Notifiable and Regulatory Works are given in Parts 1 & 2 of the Regulation respectively. Part 3 of the Regulation stipulates the general control requirements (eg site boundary and entrance) for construction dust. The control requirements for individual activities (eg stockpiling of dusty material) are given in Part 4 of the Regulation.
Except for the grade separation works in Tuen Mun, all the rail sections of the proposed alignment in Tin Shui Wai Reserve Zone will be at-grade. Site formation work has been completed and it is not necessary to conduct extensive excavation work.
For the at-grade section, the key construction activities to be carried out include minor site clearance, laying of ballast and track. These activities would not generate large amount of construction dust.
The grade separation works in Pui To Road and Tsing Lun Road would involve bore piling and the construction of superstructure for the viaduct. Again, these activities would not generate large amount of construction dust.
The Contractor is obliged to follow the procedures and requirements given in the Air Pollution Control (Construction Dust) Regulation. This requirement should be incorporated by the Detailed Design Consultant (DDC) into the Particular Specification (PS) for the civil work. The PS should also draw the Contractor’s attention to the relevant latest Practice Notes issued by EPD.
The Contractor should also be requested to conduct an audit and monitoring programme during the construction stage to ensure the construction dust impacts are controlled with the HKAQO. Detailed requirements for the audit and monitoring programme are given in Section 12.
Construction air quality impact should be minor and effective control can be achieved by implementing the procedures and requirements given in the Air Pollution Control (Construction Dust) Regulation and an audit and monitoring programme.
Railway noise is controlled under the Noise Control Ordinance (NCO)[5] and the associated Technical Memorandum on Noise from Places Other Than Domestic Premises, Public Places or Construction Sites (TM-Places) [14] .
The acceptable Noise Levels (ANLs) for different Area Sensitivity Ratings (ASRs) are summarised below:
|
ASR |
Time
Period (see Note 1) |
Acceptable Noise Levels
(ANL), L eq, 30 min |
|
A |
Day & evening |
60 dB(A) |
|
|
Night |
50 dB(A) |
|
B |
Day & evening |
65 dB(A) |
|
|
Night |
55 dB(A) |
|
C |
Day & evening |
70 dB(A) |
|
|
Night |
60 dB(A) |
Table 6.1: Acceptable Noise Levels (ANLs)
Note
1: Day
: 0700 to 1900 hours
Evening
: 1900 to 2300 hours
Night
: 2300 to 0700 hours
Additional corrections shall also be applied if the measured noise level is qualified for tonality and intermittency.
The TM-EIA [13] and HKPSG [19] also provide criteria for railway noise. These criteria are given below:
|
Parameters |
Criterion, dB(A) |
Ref |
|
Maximum A-weighted sound pressure level, Lmax (2300-0700hrs) |
85 |
TM-EIA |
|
Equivalent Continuous Sound Level, Leq (24 hours) |
65 |
HKPSG |
Table 6.2: Noise Criteria Stipulated in TM-EIA and HKPSG
Similar to railway noise, noise from associated fixed plant (eg rectifier station) is controlled by the NCO. In addition, according to TM-EIA, fixed plant noise should also be designed to be 5dB(A) below the ANL stipulated in the TM-Places. A summary of the noise limits for fixed plant is given in the following table.
|
|
|
Noise Limit, L eq,
30 min , dB(A) |
|
|
ASR |
Time
Period (see Note 1) |
ANL |
HKPSG |
|
A |
Day & evening |
60 |
55 |
|
|
Night |
50 |
45 |
|
B |
Day & evening |
65 |
60 |
|
|
Night |
55 |
50 |
|
C |
Day & evening |
70 |
65 |
|
|
Night |
60 |
55 |
Table 6.3: Noise Levels for Fixed Plant Noise
Note
1: Day
: 0700 to 1900 hours
Evening
: 1900 to 2300 hours
Night
: 2300 to 0700 hours
The study area for the noise impact assessment will include all noise sensitive receivers within 300m from the project boundaries. With the shielding from the first row of building blocks, the second row of NSRs will generally be protected. The assessment therefore focuses on the first row of NSRs that have direct line of sight to the operating trains within the project boundaries.
NSRs are chosen in accordance with Annex 13 of the TM-EIAO. Both existing and future planned uses will be included. The existing NSRs are identified through desktop review and site surveys. The planned NSRs are identified in the latest Outline Zoning Plans, and other building plans provided by Housing Authority (Appendix 3). The drawings in Appendix 2 illustrate the location plans and detailed descriptions of the NSRs proposed for the EIA study. A summary of these sensitive receivers is given below:
|
Works |
NSR / Use |
Horiz dist to rail / viaduct |
Remarks |
|
Tin Shui Wai
Reserve Zone |
Government /
Institution / Community (GIC) |
> 15m |
Subject to
detailed design by others |
|
|
Residential
areas |
15 – 60m |
With openable
windows |
|
Grade separation
work in Pui To Street |
School along
Pui To Road |
40m |
Provided with
A/C |
|
|
Residential
blocks |
10 – 40m |
With openable
windows |
|
Grade
separation work in Tsing Lun Road |
1-2 storey
houses |
> 20m |
With openable
windows |
Table 6.4: Summary of Noise Sensitive Receivers close to the Alignment
The building plans for some of the future residential areas in Tin Shui Wai Reserve Zone area are not available. In order to estimate the noise impacts on these areas, the nearest NSRs are assumed to be 15m from the site boundary, and with a view angle of 180m on the future LRT alignment.
Appendix 2 also presents the Area Sensitivity Ratings (ASRs) for the identified NSRs assumed for operational noise assessment. The ASRs for the NSRs are determined by reviewing the traffic flow data available, the TS-900 EIA report for West Rail and the existence of any Influencing Factors.
The following table summaries the ASRs for the identified NSRs.
|
NSRs
|
ASRs |
|
Residential houses near LT1, along Ng Lau Road in Lam Tei (within 100m from Tuen Mun Road) Residential blocks in Siu Hong Court near Lam Tei (within 100m from Tuen Mun Road) |
C |
|
Existing residential blocks along Pui To Road |
B |
|
Future top-side property in West Rail Tuen Mun Centre (within 100m from industrial area) |
C |
|
Future residential areas in Tin Shui Wai Reserve Zone |
B |
Table 6.5: Summary of Area Sensitivity Ratings for Identified NSRs
The ASRs assumed are indicative only based on the latest information available. It should be noted that fixed noise sources are controlled under Section 13 of the NCO. At the time of investigation, EPD will determine noise impact from concerned fixed noise sources on the basis of prevailing legislation and practices being in force, taking account of contemporary conditions / situations of adjoining land uses.
KCR has provided the train noise data in Lmax for LRV (both new and existing trains). The Lmax data has been converted to SEL using established train noise prediction methodology[25]. A summary of the noise data and the corresponding operating conditions is given below:
|
Parameters |
Noise Data / Operating Conditions |
|
Lmax |
: 65 dB(A) |
|
Track
form |
: Ballast track in well maintained condition |
|
Speed |
: 50kph |
|
Distance |
: 25m |
|
Length
of train |
: 40m (for 2-car trains) |
Table 6.6 Summary of Train Noise Data Provided by KCR
A 3dB(A) correction is included in the prediction model to allow for the rail deterioration.
The train speeds
for various rail sections are prepared by KCRC and LRT (Appendix 4). These speeds are the practical average
travel speed, taking into account the speed limits at junctions and across
roads.
The correction of Lmax for train speeds is based on the following equation [25]:
Change of Lmax
with speed = 30 log (V1 / V2) dB(A)
Where V1 and V2 are
the average train speeds.
The correction of Lmax for distance is based on the following equation:
Change of Lmax
with distance = 10 log (d1 / 25) dB(A)
Where d1 is the distance between
track and receiver.
Ballast track would be used for the track in Tin Shui Wai reserve Zone. For the grade separation works in Pui To Road, ballast track will be used except for the section directly underneath the deck of the future West Rail Tuen Mun Station. For the grade separate work in Tsing Lun Road, paved track will be used. The following corrections are applied for the reflection from the deck of viaduct.
· Viaduct with ballast track = 1.5dB(A)
· Viaduct without ballast track = 2.5dB(A)
There will be no cross-over in the proposed LRT. A 7dB(A) correction is included in the model to represent the argumentation in noise due to thermal expansion joints.
It has been advised by KCR that Continuously Welded Rail (CWR) will be adopted for the proposed LRT works. There would be neither thermal expansion joints nor structural breaks for the rail on viaduct.
Wheel squeal would occur when wheelset negotiate sharp curves. For non-resilient wheels, researches have indicated that it may have squeal when the radius of curvature is less than 100 times of the wheelbase [25]. Other study [31] has concluded that resilient wheels are effective measures to control wheel squeal noise. That report also quoted that the use of resilient wheels would control squeal noise for radius of curvature less than 30m.
It has been advised by KCR that both the existing and future LRT trains are provided with resilient wheels, with a wheelbase of about 1.9m. For a conservative assessment however, this assessment has incorporated wheel squeal correction of 3dB(A) for curves with radius of curvatures less than 200m (including temporary track). For NSRs within 25m from such a curve, an additional correction of 3dB(A) would be allowed.
|
The calculation of SEL from L max is based on the following equation [25] |
|
SEL = L max + 10 log (L/V) +10.5 –10 log (4D / (4D2+1) + 2 tan-1 (1/2D)) Where L = train length, m V = train speed, kph d = Distance from track, m D = d / L |
The predicted train frequencies (for before Year 2003 and up to Year 2011) during AM peak hour for various alignment sections has been provided by KCR . The train frequency for before Year 2003 will be adopted for the assessment on the temporary diversion in Pui To Road and Tsing Lun Road.
It has also been advised by LRT that the hourly train frequency during early morning before 0700 hours (ie 0630 to 0700 hours) would be 100% of the AM peak (Appendix 4). The train frequency during AM peak will therefore be adopted for the night-time noise assessment.
The correction of SEL for train frequency is calculated based on the following equation:
Change of SEL with train
frequency = 10 log (N1) dB(A)
Where N1 is the train frequency
for the rail segment.
The correction for view angles is based on the following equation:
Change of SEL with view
angle = 10 log (f/180) dB(A)
Where f is the view angle.
A 2.5dB(A) correction will be applied for all receivers to account for the façade reflection effect.
The proposed LRT alignments are arranged alongside the West Rail alignment in Tsing Lun Road, Lam Tei. For NSRs that are affected by both the LRT and West Rail alignments, additional noise contributions from West Rail has been included in the noise assessment to determine the cumulative noise impacts. The noise contributions from West Rail were extracted from the West Rail calculations (Appendix 5).
In order to estimate the magnitude of re-radiated noise from viaduct structure, noise measurements have been conducted to establish the noise re-radiated from existing LRT viaduct structures.
The location was close to Junction MJ9 (ie under the viaduct connecting Fung Tai Stop and Siu Hong Stop, and near Tuen Mun Government Primary School). The measurement location was directly underneath the existing concrete viaduct, with a head room of approximately 5-6m. Ballast track was installed. Trains were travelling at approximately 40-50kph.
The measured train noise levels are corrected to a distance of 25m (Figure 6.1) for comparison with the train noise data provided by KCR. A summary of the comparison is given below:
|
Location |
Measured L max, dB(A) |
Dist corr, dB(A) |
Corrected Lmax,
dB(A) |
LRT Noise Data, Lmax
dB(A) |
|
Near Tuen Mun Government Primary School |
60 – 63 |
-8 |
52 – 55 |
65 |
Table 6.7: Comparison of Measured Structure Re-radiated Noise and KCR’s Noise Data
The corrected structure re-radiated noise levels are at least 10dB(A) less than the noise data of 65dB(A) Lmax (at the reference conditions) provided by KCR. In this respect, the noise contribution from structure re-radiated noise from concrete viaduct structure would be more than 10dB(A) below the calculated airborne noise impacts. Since the cumulative noise impacts (ie with contributions from West Rail) will be controlled to within the ANL limits, the structure re-radiation noise would not have significant contributions on the cumulative noise impacts.
As advised by LRT, the definitions of Normal, Abnormal and Emergency Operations for LRT are as follows (see Appendix 6):
Normal The day-to-day operations without any interruption causing service delay.
Abnormal - The planned or expected event / happening which is not day-to-day or infrequent nature (eg engineering or operational adjustment catering for extended LRV services) or incidents resulting in service disruption less than 20 minutes).
Emergency - An unexpected occurrence that has environmental impact (eg spillage of chemical) or major incident as defined in the Procedure Manual of Contingencies.
Under the “Abnormal Operations”, the operation time of LRT will be extended from 0130 hours by another 1 –2 hours. These “Abnormal Operations” will occur during special periods (eg Chinese New Year and Christmas). Although the services period is extended in these occasions, the hourly train frequency will remain the same as that during “Normal” operation. The noise assessment during “Normal” operations will therefore also cover the “Abnormal” operation periods.
The controlling noise parameter would be the night-time noise impacts (ie Leq, 30 min) since the train frequency during early morning (ie 0630 to 0700) would be 100% of AM peak and the noise criterion before 0700 hours would be the one for night-time period. Given that the Lmax is only 65dB(A) at 25m from track, all the NSRs would not be exposed to noise levels exceeding the stipulated 85dB(A) Lmax criterion.
Air-borne rail noise prediction has been conducted according to the methodology described above. Appendix 7 presents a summary of the predicted cumulative train noise impacts.
Results indicate that the cumulative noise impacts (for year up to 2011) at all the NSRs would be within the stipulated noise limits. A summary of the predicted cumulative noise impacts for representative NSRs is given below (see Appendix 7 for details):
|
NSR |
Description |
Predicted
Noise Impacts, dB(A) |
Criteria,
dB(A) |
Compliance |
|
N105 |
TSW Area 31
Phase 1 Block 1 |
54 |
55 |
Yes |
|
N115 |
TSW Area 30
Block 4 |
54 |
55 |
Yes |
|
N123 |
TSW Area 102
Block 4 |
53 |
55 |
Yes |
|
N127 |
TSW Area 102
Block 15 |
52 |
55 |
Yes |
|
N130 |
TSW Area 102
Block 18 |
46 |
55 |
Yes |
|
N138 |
TSW Area 110
Phase 2 |
49 |
55 |
Yes |
|
N149 |
TSW Area 111
Block 1 |
52 |
55 |
Yes |
|
N151 |
TSW Area 111
Block 5 |
52 |
55 |
Yes |
|
N153 |
TSW Area 111
Block 9 |
52 |
55 |
Yes |
|
N45 |
Castle Peak
Catholic Primary School |
50* |
65 |
Yes |
|
N50 |
Tuen Mun Town
Plaza (Block 1) |
47* |
55 |
Yes |
|
N55 |
Tuen Mun Town
Plaza (Block 8) |
49* |
55 |
Yes |
|
N83 |
Future top-side
property in West Rail Tuen Mun Centre (within 100m from industrial area) |
55* |
60 |
Yes |
|
N48 |
Kam Wah Garden |
49* |
55 |
Yes |
|
N70 |
Residential
houses near LT1, along Ng Lau Road in Lam Tei (within 100m from Tuen Mun
Road) |
49* |
60 |
Yes |
|
N73 |
Yau Tze Tin
Memorial College |
54* |
65 |
Yes |
Table 6.8 : Summary of Predicted Cumulative Noise Impacts (up to 2011)
* with
West Rail contribution
During the construction period when temporary diversion at Pui To Road and LT1 are required, the predicted cumulative noise impacts are also within the criteria. The following table summaries the results.
|
Description |
Predicted Noise Impacts, dB(A) |
Criteria, dB(A) |
Compliance |
|
|
N70 |
Residential houses near LT1, along Ng Lau Road in
Lam Tei (within 100m from Tuen Mun Road) |
54* |
60 |
Yes
|
|
N45 |
Castle Peak Catholic Primary School |
50* |
65 |
Yes
|
|
N50 |
Tuen Mun Town Plaza (Block 1) |
48* |
55 |
Yes
|
|
N48 |
Kam Wah Garden |
49* |
55 |
Yes
|
Table 6.9 : Summary of Predicted Cumulative Noise Impacts (before 2003)
·
with West Rail contribution
The proposed LRT works include a rectifier station (ie R16 for Tin Shui Wai Reserve Zone) that is a potential fixed noise source. It has been advised that the transformer to be installed in the rectifier stations would be similar to those that have been currently installed in Tuen Mun and Tin Shui Wai areas. Transformer bays will be provided with a concrete cover and opened on one side. Other equipment (eg switching gears) will be accommodated in plant rooms.
Noise measurement results indicate that the outdoor transformers in existing rectifier stations would generate a noise level of 64 – 66dB(A) at a distance of 2m, when there are two transformers operating simultaneously. The measurements were taken during peak hour when the loading of the transformers was close to the maximum.
The assessment assumes “point source” dispersion with correction factors of 3dB(A) for tonality and 3dB(A) for façade effect. Possible screening effects from the rectifier station structure have not been included for a conservative assessment. All the transformers in the rectifier stations are assumed to be operating in the noise assessment.
The noise impacts caused by the transformers have been conducted based on the measured transformer noise levels and the methodology described above. Calculations indicated that the predicted noise impacts, based on the measured noise data for existing transformers, would be in the range of 41-47 dB(A) for the NSRs near R16. These noise levels are within the NCO-5 limit of 50dB(A). Calculations of noise impacts are presented in Appendix 9.
Although the predicted noise impacts are within the specified noise limits, the Detailed Design Consultant is still recommended to orientate the transformer bays in such a way that the open sides are not facing the nearest NSRs, and preferably facing onto a main road, if it is practicable.
Other potential noise sources in rectifier station include the ventilation system for switch rooms. It is recommended that a review to be conducted during the Detailed Design Stage to ensure that adequate noise attenuation treatments (eg silencers, acoustic louvres) are incorporated into the detailed design of the ventilation system to ensure compliance with the relevant noise criteria.
The findings of operational noise assessments indicate that there would not be any adverse impacts on the neighbouring NSRs. It is not required to implement specific noise mitigation measures for the proposed LRT Works. However, the following recommendations should be implemented during the design and operational stages of the proposed works.
· The railway operator should ensure that the worst-case noise level of 65 dB(A) Lmax at 25m from straight and well maintained ballast track is always achieved.
· The Detailed Design Consultant should ensure that the structure re-radiated noise from viaduct structure is at least 10dB(A) below the noise criteria of 65 dB(A) Lmax at 25m, at 50kph.
· The Detailed Design Consultant should ensure that the noise level at 2m from the transformer bays in the rectifier would be less than 66dB(A).
· The Detailed Design Consultant should orientate the open side of transformer bays in rectifier station to face away from the nearest NSRs, and preferably facing onto a main road, if practicable.
· The Detailed Design Consultant should conduct a detailed review on ventilation systems in the rectifier stations to determine the need for any noise attenuation (eg silencers, acoustic louvres etc).
Assessments of airborne noise and structure re-radiated noise have been conducted based on the train noise data provided by KCR and the methodology described in this section. Results indicate the cumulative noise impacts would be within the stipulated noise criteria. Recommendations are given for the railway operator and the Detailed Design Consultants to ensure compliance with the requirements given in TM-EIA.
Control over the generation of construction noise in Hong Kong is governed by the NCO[5] and the EIAO[2] and their subsidiary requirements. Various Technical Memoranda (TMs) have been issued under the NCO and the EIAO to stipulate control approaches and criteria. These TMs prescribe the maximum permitted noise levels for the use of Powered Mechanical Equipment (PME) and certain construction activities and processes, according to the type of equipment or activity, the perceived noise climate of the area, and the working hours of equipment operation and usage. The TMs applicable to the control of noise from construction activities in current proposed LRT works are:
· Technical Memorandum on Noise from Construction Work other than Percussive Piling [15] (TM-CW);
· Technical Memorandum on Noise from Construction Work in Designated Areas [16] (TM-DA); and
· Technical Memorandum on Environmental Impact Assessment Process [13] (TM-EIA).
Noise arising from general construction works during normal working hours is governed by the TM-EIA under the EIAO. The following table presents the recommended noise standards.
Uses |
Acceptable Noise Standards Leq (30mins), dB(A) |
|
All domestic premises including temporary housing accommodation |
75 |
|
Hotels and hostels |
75 |
|
Educational institutions including kindergartens, nurseries and all others where unaided voice communication is required |
70 65 (During examinations) |
Note: The above standards
apply to uses which rely on opened windows for ventilation.
Table 7.1: Noise Standards for Daytime (0700 to 1900 hours) Construction Activities
In accordance with the TM-EIA, the noise criteria as laid down in the above table for the construction of designated project shall be met as far as practicable. All practicable mitigation measures shall be exhausted and the residual impacts are minimised.
The NCO provides statutory controls on general construction works during the restricted hours (ie 1900 to 0700 hours from Monday to Saturday and at any time on Sundays or public holidays). The use of Powered Mechanical Equipment (PME) for construction works during the restricted hours would require a Construction Noise Permit (CNP). The TM-CW details the procedures adopted by EPD for assessing such application. The granting of a CNP is subject to conditions stated in the permit and it may be revoked at any time for failure to comply with the stated conditions.
In addition to the general controls on the use of PME during the restricted hours, the use of Specified Powered Mechanical Equipment (SPME) and the undertaking of Prescribed Construction Work (PCW) during the restricted hours in a designated area are controlled by the TM-DA. Construction plant or equipment classified as SPME under the TM-DA includes hand-held breakers, bulldozers, concrete mixer lorries, dump trucks and poker vibrators. PCW includes the erection or dismantling of formwork or scaffolding, hammering, handling of rubble, wooden boards, steel bars, or scaffolding material, and the disposal of rubble through plastic chutes.
The TM-DA details the procedures that would generally be adopted by EPD for assessing the use of SPME during the restricted hours and for determining whether a CNP would be issued.
Maximum noise levels from construction activities during the restricted hours at affected NSRs are controlled under the TMs and shall not exceed the specified Acceptable Noise Levels (ANLs). These ANLs are stipulated in accordance with the Area Sensitivity Ratings (ASRs) established for the NSRs. The ANLs for construction works in designated areas are more stringent than those given in the TM-CW, as reflected from the corresponding Basic Noise Levels (BNLs) stated in the following table.
Time Period |
Area Sensitive Ratings |
||
|
A |
B |
C |
|
|
All weekdays during the evening (1900 to 2300 hours), and general holidays (including Sundays) during the day and evening (0700 to 2300 hours) |
60(45) |
65(50) |
70(55) |
|
All days during the night-time (2300 to 0700 hours) |
45(30) |
50(35) |
55(40) |
Note: Figures in brackets are BNLs for
SPME construction work in designated areas
Table 7.2: BNLs for Construction Noise other than Percussive Piling
The eastern section of Pui To Road Grade Separation site (from Tuen Mun River Channel) lies within the Designated Area as defined in the Noise Control Designated Area Plan no. EPD/NP/KLN-01. Tin Shui Wai Reserve Zone Extension, LT1 Grade Separation and the western section of Pui To Road Grade Separation do not lie within the Designated Area.
Under the current plan of construction schedule from periods March 2001 to November 2003, the construction works would be carried out at normal working hours only (ie 0700 to 1900 hours on any day other than Sunday or public holiday) and it would not be required to carry out construction works during the restricted hours (ie 1900 to 0700 hours from Monday to Saturday and at any time on Sundays and public holidays). This assessment therefore focuses on the construction works during the normal working hours.
However, should construction works during restricted hours are found to be necessary, the Contractor shall apply for a Construction Noise Permit (CNP) from the Noise Control Authority. Despite any description or assessment made in this EIA Report on construction noise aspects, 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 Technical Memoranda issued under the Noise Control Ordinance. The Noise Control Authority will take into account of contemporary conditions/situations of adjoining land uses and any previous complaints against construction activities at the site before making his decision in granting a CNP. Nothing in this 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 he thinks fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.
The following procedures apply to the assessment of construction noise impacts:
· locate representative NSRs that may be affected by the works;
· determine plant items for corresponding construction activities based on the agreed plant inventories with KCRC;
· determine the sound power levels of the plant items according to the information stated in the TM-CW or other recognised sources of reference, where appropriate;
· calculate the correction factors based on the distance between the NSRs and the notional noise source positions of the work sites;
· apply corrections including façade, distance, barrier attenuation, acoustic reflection where applicable, in the calculations;
·
predict construction noise levels at the NSRs in the absence of any
mitigation measures;
·
conduct assessment of noise impacts at NSRs to quantify the level of
impact, in accordance with TM-CW.
An in-house program was used to facilitate the
analysis of the construction noise calculations. The initial program runs were conducted without any
mitigation measures. Where noise
level exceedances were identified, further runs were made assuming different
combinations of mitigation measures to be incorporated to control noise
impacts.
Where noise exceedances from assessment criteria were found at the NSRs, appropriate mitigation measures would be evaluated and recommended. A systematic approach to the evaluation of mitigation measures has been adopted, consisting of four levels of mitigation (and combination of each level) as described below.
|
Mitigation |
Description |
|
M1:
Level One |
Selection of quiet plant and working methods |
|
M2: Level Two |
Construction of temporary noise barriers |
|
M3: Level Three |
Delocalization of equipment and/or local reduction of number of plant items |
|
M4: Level Four |
Limiting equipment operating time |
Table 7.3: Construction Noise Mitigation Strategy
Some models of plant are quieter than the standard types listed in the TM-CW. Quiet plant is defined as PME whose actual SWL is less than the value specified in the TM-CW for the same piece of equipment. The benefits achieved in using quiet plant will depend on Contractor’s selection of working method. Examples of SWLs of specific silenced PME that may be used in the construction of the project worksites are given in BS5228 Part I, detailed in Section 7.3.5.3.
In general, noise barriers of 3 to 5 metres high located on site boundaries between noisy construction activities and NSRs could give up to 5-10 dB(A) reduction from screening. With careful consideration in the location of site access for the effectiveness of the barriers, barriers in the form of site hoardings could achieve this level of reduction. Certain types of PME, such as generators and compressors, can be partially or completely enclosed to give a total SWL reduction of 15-25 dB(A). Movable barriers that can be located close to noisy plant can also be very effective at screening NSRs from particular plant. This measure is particularly effective for low-rise noise sensitive premises or schools.
For the same set of plant items, delocalization of equipment or avoiding all equipment operating at the same site location would reduce the noise impact from construction activities on nearby NSRs. This approach is very effective for construction work site of linear shape. Delocalization of identical plant may include eg separating two dump trucks (or two concrete lorry mixers or two excavators) by more than 200m apart such that they would not be operated at the same working area. For the NSR close to the construction work site (less than 50m), the noise contribution from the distant PME would be insignificant.
Selection of the number and types of construction plant is usually left to the Contractor to allow flexibility in devising efficient working methodologies. However, in combination with the selection of quiet plant and noise barriers, limiting plant numbers may be required to provide further mitigation of construction noise levels at source in critical areas.
By restricting the percentage of operation of PME to 50% within 30-minute period, a noise reduction of 3 dB(A) could be achieved. Construction plant including dump truck may be used with careful attention to ensure that the engines are switched off or only idling at low power setting when not in direct use. For these PME the operating time should be carefully controlled so that they are only operating for 15 minutes in every consecutive 30-minute period.
NSRs have been identified in accordance with HKPSG
and the TM-EIA. A comprehensive list of all the identified NSRs for assessment
of operational noise impacts was prepared and presented in Appendix 2. These NSRs would also be affected by
the construction works during the construction stage. The worst affected NSRs during the construction phase of the
proposed LRT works have been considered.
The study areas will consist of three separated worksites. The three worksites that have been taken into consideration for the assessment are:
· Pui To Road Grade Separation (Worksite 1);
· LT1 Grade Separation (Worksite 2); and
· Tin Shui Wai Reserve Zone Extension (Worksite 3)
The landuses in the vicinity of the proposed alignment and LRT stops include schools and residential developments. The key representative NSRs for construction noise assessment are listed in the table. The separation distances of the NSRs to the construction sites are described in detail in Appendix 10.
Site
Area |
NSR |
Description |
|
Worksite 1- Pui To
Road Grade Separation |
N42# |
Fire Station and Ambulance |
|
N46 |
Top Court |
|
|
N47 |
Man Shing Building |
|
|
N48 |
Kam Wah Garden Block 1 |
|
|
N49 |
Kam Wah Garden Block 2 |
|
|
N50 |
Tuen Mun Town Plaza Block 1 |
|
|
N51 |
Tuen Mun Town Plaza Block 2 |
|
|
N53 |
Sun Court Podium |
|
|
N55 |
Tuen Mun Town Plaza Block 8 |
|
|
N200 |
San Fat Estate |
|
|
Worksite 2-LT1 Grade
Separation |
N64 |
2-storey residential house |
|
N65 |
3-storey residential house |
|
|
N66 |
Care Home for the Elderly |
|
|
N68 |
2-storey residential house |
|
|
N69 |
2-storey residential house |
|
|
N71 |
1-storey residential house |
|
|
N72 |
2-storey residential house |
|
|
N73 |
You Tze Tin Memorial
College |
|
|
N74 |
Siu Tai House |
|
|
N76 |
Siu Ping House |
|
|
Worksite 3- Tin Shui
Wai Reserve Zone |
N35 |
Shap Pat Heung Rural
Committee Kung Yik She Secondary School |
|
N38 |
Lynwood Court Block 10 |
|
|
N89 |
Tin Shui Wai Area 105 Phase
1 Block 5 |
|
|
N106 |
Tin Shui Wai Area 31 Phase
1 Block 2 |
|
|
N107 |
Tin Shui Wai Area 31 Phase
1 Block 3 |
|
|
N115 |
Tin Shui Wai Area 30 Block
4 |
|
|
N118 |
Tin Shui Wai Area 31 Phase
1 Primary School |
|
|
N120 |
Tin Shui Wai Area 31 Phase
2 Primary School |
|
|
N123 |
Tin Shui Wai Area 102 Phase
1 Block 4 |
|
|
N129 |
Tin Shui Wai Area 102 Phase 5 Block 17 |
|
|
N137 |
Tin Shui Wai Area 110 Phase
2 Block 11 |
|
|
N138 |
Tin Shui Wai Area 110 Phase
2 Block 10 |
|
|
N155 |
Tin Shui Wai Area 30 Phase
1 Block 6 Domestic (4/F-6/F) |
|
|
N155a |
Tin Shui Wai Area 30 Phase
1 Block 6 Kindergarten (3/F) |
# It was advised by the management of the
Fire Station and Ambulance that there were no staff quarters and residential
accommodations within the Fire Station area, and the Fire Station is not
considered as NSR in this assessment.
Table 7.4: Listing of Key Representative NSRs for Construction Noise Assessment
Potential impacts on NSRs during the construction
phase of the project will arise mainly from PME to be operated at the
construction worksites. The
proposed LRT alignment will be both at grade and elevated. The construction period would be from
March 2001 to November 2003 according to KCRC. The LRT extension and alteration construction works will
include the following key activities:
·
at-grade alignment construction;
·
standard viaduct construction (R.C. structure); and
·
LRT stop construction.
The activities that may introduce potential noise
impacts will include:
·
site clearance and formation activities where it is proposed that
excavator, vibratory rollers and dump trucks are used;
·
LRT stop construction where it is proposed to use concrete lorry mixers
and pokers;
·
track laying involving tampering machine and mobile crane operation;
·
piling where it is proposed to use reverse circulation drills, concrete
lorry mixers and pokers;
·
pile cap construction involving excavator/loader, concrete lorry mixer
and poker operations;
·
column construction where it is proposed to use concrete lorry mixers,
pokers and mobile cranes; and
·
superstructure construction where it is proposed to use concrete lorry
mixers, pokers and mobile cranes.
The construction of the proposed LRT works involves
different construction activities and plant at different stages. KCRC has provided construction plant
inventories with the necessary quantity of plant to carry out the construction
works. It is understood that the
use of these plant and equipment would be KCRC’s preferred approach to the
construction. Appendix 11 gives
details of these plant inventories and construction schedules. This construction noise assessment has
been based on these plant inventories for impact modelling.
A brief description of works to be undertaken at
each worksite and the total SWLs for the plant in the absence of any mitigation
measures are presented in the following table.
|
Site
Area |
Activity No. |
Construction
Activities Description |
Total Unmitigated SWL(1).
dB(A) |
|
Worksite 1 – Pui To Road Grade Separation |
1 |
Site Clearance (SCF) |
121 |
|
2 |
Piling (PIL) |
122 |
|
|
3 |
Pile Cap Construction (PCC) |
122 |
|
|
4 |
Backfilling (BF) |
119 |
|
|
5 |
Column Construction (CLC) |
122 |
|
|
6 |
Superstructure Construction (SSC) |
122 |
|
|
7 |
Track Laying (TRL) |
120 |
|
|
8 |
Installation of Overhead Line Cable (OLC) |
118 |
|
|
9 |
Site Reinstatement (SRE) |
121 |
|
|
10 |
Road Reinstatement (RRE) |
114 |
|
|
Worksite 2 – LT1 Grade Separation |
1 |
Site Clearance (SCF) |
121 |
|
2 |
Piling (PIL) |
122 |
|
|
3 |
Pile Cap Construction (PCC) |
122 |
|
|
4 |
Backfilling (BF) |
119 |
|
|
5 |
Column Construction (CLC) |
122 |
|
|
6 |
Superstructure Construction (SSC) |
123 |
|
|
7 |
Track Laying (TRL) |
120 |
|
|
8 |
Installation of Overhead Line Cable (OLC) |
118 |
|
|
9 |
Site Reinstatement (SRE) |
121 |
|
|
10 |
Road Reinstatement (RRE) |
114 |
|
|
Worksite 3 – Tin Shui Wai Reserve Zone
Extension |
1 |
Site Clearance and Formation (SCF) |
125 |
|
2 |
LRT Stop Construction (LSC) |
122 |
|
|
3 |
Backfilling (BF) |
119 |
|
|
4 |
Track Laying (TRL) |
120 |
|
|
5 |
Installation of Overhead Line Cable (OLC) |
119 |
[1]
Based on
KCRC’s plant inventories
Table 7.5: Total Unmitigated SWLs for Construction Activities
The construction works will generally be restricted
to normal daytime working hours.
Construction noise impacts are predicted in the following sections.
In accordance with the current construction
schedules of LRT and West Rail (Appendix 11), the two projects have no
over-lapping construction period except that the LRT site formation work at Pui To Road (ie LRT Tuen Mun Station
and San Fat LR Stop) would be
overlapping with beam erection and station construction of West Rail.
In order to address the cumulative noise impact from
West Rail construction during the overlapping period, all identified LRT NSRs
at Pui To Road have been detail examined with the EPD endorsed West Rail Final
EIA Report. This establishes the noise criteria for LRT construction such that
the overall construction noise level at all NSRs will be within the 75dB(A)
daytime construction noise limit. Table 7.7 below summarises the findings of
the examination.
|
NSR |
Description |
Maximum Noise Contribution from West Rail Construction, dB(A) |
Adopted
LRT Construction Noise Criteria, dB(A) |
|
N46 |
Top Court |
#71 |
73 |
|
N47 |
Man Shing Building |
#71 |
73 |
|
N48 |
Kam Wah Garden Block 1 |
#71 |
73 |
|
N49 |
Kam Wah Garden Block 2 |
#71 |
73 |
|
N50 |
Tuen Mun Town Plaza Block 1 |
#71 |
73 |
|
N51 |
Tuen Mun Town Plaza Block 2 |
#71 |
73 |
|
N53 |
Sun Court Podium |
#71 |
73 |
|
N55 |
Tuen Mun Town Plaza Block 8 |
#71 |
73 |
|
N200 |
San Fat Estate |
#75 |
- (Note 2) |
Note:
1.
The maximum
noise contributions from West Rail construction are taken from the Final EIA
Report for West Rail.
2.
It was
advised by Housing Department that San Fat Estate was
scheduled to evacuate by March 2001 whereas LRT
construction at that location would commence at April 2001. San Fat Estate is
therefore not considered as NSRs in the assessment.
Table 7.6: Cumulative Construction Noise Criteria
The adopted LRT construction noise criteria of
73dB(A) for the above NSRs may be relaxed with a detailed assessment on West
Rail construction plant schedule. It is recommended that such detailed
construction noise impact assessment be conducted during the construction stage
in order to allow more flexibility for the Contractor to select different plant
items to suit his own construction method and schedule.
Façade
noise levels at the NSRs were calculated [27] based on the SWLs and
corrections for distance attenuation given in the TM-CW. The predicted unmitigated maximum
noise levels at the key representative NSRs at ground level zone during the
construction phase of the LRT works are shown below.
|
NSR |
Description |
Activities in Each Construction Phase(1,2) |
||||||||||||
|
|
|
|
SCF |
LSC |
PIL |
PCC |
BF |
CLC |
SSC |
TRL |
OLC |
SRE |
RRE |
|
|
Worksite1-Pui To |
N46 |
Top
Court |
82 (9) |
- |
83 (10) |
83 (10) |
80 (7) |
83 (10) |
83 (10) |
81 (8) |
79 (6) |
82 (9) |
75 (2) |
|
|
Road Grade Separation |
N47 |
Man
Shing Building |
84 (11) |
- |
85 (12) |
85 (12) |
82 (9) |
85 (12) |
85 (12) |
83 (10) |
81 (8) |
84 (11) |
77 (4) |
|
|
|
N48 |
Kam
Wah Garden Block 1 |
85 (12) |
- |
86 (13) |
86 (13) |
83 (10) |
86 (13) |
86 (13) |
84 (11) |
82 (9) |
85 (12) |
78 (5) |
|
|
|
N49 |
Kam
Wah Garden Block 2 |
84 (11) |
- |
85 (12) |
85 (12) |
82 (9) |
85 (12) |
85 (12) |
83 (10) |
81 (8) |
84 (11) |
77 (4) |
|
|
|
N50 |
Tuen
Mun Town Plaza Block 1 |
90 (17) |
- |
91 (18) |
91 (18) |
88 (15) |
91 (18) |
91 (18) |
89 (16) |
87 (14) |
90 (17) |
83 (10) |
|
|
|
N51 |
Tuen
Mun Town Plaza Block 2 |
83 (10) |
- |
84 (11) |
84 (11) |
81 (8) |
84 (11) |
84 (11) |
82 (9) |
80 (7) |
83 (10) |
76 (3) |
|
|
|
N53 |
Sun
Court Podium |
85 (12) |
- |
86 (13) |
86 (13) |
83 (10) |
86 (13) |
86 (13) |
84 (11) |
82 (9) |
85 (12) |
78 (5) |
|
|
|
N55 |
Tuen
Mun Town Plaza Block 8 |
86 (13) |
- |
87 (14) |
87 (14) |
84 (11) |
87 (14) |
87 (14) |
85 (12) |
83 (10) |
86 (13) |
79 (6) |
|
|
|
N200 |
San
Fat Estate |
84 (11) |
- |
84 (11) |
84 (11) |
82 (9) |
84 (11) |
84 (11) |
83 (10) |
81 (8) |
84 (11) |
77 (4) |
|
|
Worksite2-LT1 |
N64 |
2-storey
residential house |
76 (1) |
- |
77 (2) |
77 (2) |
74 (0) |
77 (2) |
78 (3) |
75 (0) |
73 (0) |
76 (1) |
69 (0) |
|
|
Grade Separation |
N65 |
3-storey
residential house |
82 (7) |
- |
83 (8) |
83 (8) |
80 (5) |
83 (8) |
84 (9) |
81 (6) |
79 (4) |
82 (7) |
75 (0) |
|
|
|
N66 |
Care
Home for the Elderly |
74 (0) |
- |
75 (0) |
75 (0) |
72 (0) |
75 (0) |
76 (1) |
73 (0) |
71 (0) |
74 (0) |
67 (0) |
|
|
|
N68 |
2-storey
residential house |
71 (0) |
- |
72 (0) |
72 (0) |
69 (0) |
72 (0) |
73 (0) |
70 (0) |
68 (0) |
71 (0) |
64 (0) |
|
|
|
N69 |
2-storey
residential house |
88 (13) |
- |
89 (14) |
89 (14) |
86 (11) |
89 (14) |
90 (15) |
87 (12) |
85 (10) |
88 (13) |
81 (6) |
|
|
|
N71 |
1-storey
residential house |
88 (13) |
- |
89 (14) |
89 (14) |
86 (11) |
89 (14) |
90 (15) |
87 (12) |
85 (10) |
88 (13) |
81 (6) |
|
|
|
N72 |
2-storey
residential house |
70 |
- |
71 |
71 |
68 |
71 |
72 |
69 |
67 |
70 |
63 |
|
|
|
N73 |
You
Tze Tin Memorial College |
74 (4) |
- |
75 (5) |
75 (5) |
72 (2) |
75 (5) |
76 (6) |
73 (3) |
71 (1) |
74 (4) |
67 (0) |
|
|
|
N74 |
Siu
Tai House |
77 (2) |
- |
78 (3) |
78 (3) |
75 (0) |
78 (3) |
79 (4) |
76 (1) |
74 (0) |
77 (2) |
70 (0) |
|
|
|
N76 |
Siu
Ping House |
80 (5) |
- |
81 (6) |
81 (6) |
78 (3) |
81 (6) |
82 (7) |
79 (4) |
77 (2) |
80 (5) |
73 (0) |
|
|
Worksite3-Tin Shui Wai
Reserve zone |
N35 |
Shap
Pat Heung Rural Committee Kung Yik She Secondary School |
76 |
73 |
- |
- |
70 |
- |
- |
71 |
70 |
- |
- |
|
|
Extension |
N38 |
Lynwood
Court Block 10 |
76 (1) |
73 (0) |
- |
- |
70 (0) |
- |
- |
71 (0) |
70 (0) |
- |
- |
|
|
|
N89 |
Tin
Shui Wai Area 105 Phase 1 Block 5 |
81 (6) |
78 (3) |
- |
- |
75 (0) |
- |
- |
76 (1) |
75 (0) |
- |
- |
|
|
|
N106 |
Tin
Shui Wai Area 31 Phase 1 Block 2 |
78 (3) |
75 (0) |
- |
- |
72 (0) |
- |
- |
73 (0) |
72 (0) |
- |
- |
|
|
|
N107 |
Tin
Shui Wai Area 31 Phase 1 Block 3 |
79 (4) |
76 (1) |
- |
- |
73 (0) |
- |
- |
74 (0) |
73 (0) |
- |
- |
|
|
|
N115 |
Tin
Shui Wai Area 30 Block 4 |
81 (6) |
78 (3) |
- |
- |
75 (0) |
- |
- |
76 (1) |
75 (0) |
- |
- |
|
|
|
N118 |
Tin
Shui Wai Area 31 Phase 1 Primary School |
82 (12) |
79 (9) |
- |
- |
76 (6) |
- |
- |
77 (7) |
76 (6) |
- |
- |
|
|
|
N120 |
Tin
Shui Wai Area 31 Phase 2 Primary School |
89 (19) |
86 (16) |
- |
- |
83 (13) |
- |
- |
84 (14) |
83 (13) |
- |
- |
|
|
|
N123 |
Tin
Shui Wai Area 102 Phase 1 Block 4 |
85 (10) |
82 (7) |
- |
- |
79 (4) |
- |
- |
80 (5) |
79 (4) |
- |
- |
|
|
|
N129 |
Tin
Shui Wai Area 102 Phase 5 Block 17 |
85 (10) |
82 (7) |
- |
- |
79 (4) |
- |
- |
80 (5) |
79 (4) |
- |
- |
|
|
|
N137 |
Tin
Shui Wai Area 110 Phase 2 Block 11 |
83 (8) |
80 (5) |
- |
- |
77 (2) |
- |
- |
78 (3) |
77 (2) |
- |
- |
|
|
|
N138 |
Tin
Shui Wai Area 110 Phase 2 Block 10 |
80 (5) |
77 (2) |
- |
- |
74 (0) |
- |
- |
75 (0) |
74 (0) |
- |
- |
|
|
|
N155 |
Tin
Shui Wai Area 30 Phase 1 Block 6 Domestic (4/F-6/F) |
87 (12) |
84 (9) |
- |
- |
81 (6) |
- |
- |
82 (7) |
81 (6) |
- |
- |
|
|
|
N155a |
Tin Shui Wai Area 30 Phase
1 Block 6 Kindergarten (3/F) |
87 (17) |
84 (14) |
- |
- |
81 (11) |
- |
- |
82 (12) |
81 (11) |
- |
- |
|
Note:
(1) SCF : Site Clearance & Formation; LSC: LRT Stop Construction; PIL: Piling; PCC: Pile Cap Construction; BF: Backfilling; CLC: Column Construction; SSC: Superstructure Construction; TRL: Track Laying; OLC: Installation of Overhead Line Cable; SRE: Site Reinstatement; RRE: Road Reinstatement.
(2) Exceedances from daytime noise criteria (Table 7.1) are shown with brackets
Table 7.7: Unmitigated Predicted Noise Levels at Ground Level Zone of NSRs
The noise impacts at 5th floor level, 10 floor level up to 30 floor level in 5 floor level steps are also predicted, where appropriate for each NSR. Detailed analysis indicates that the predicted unmitigated maximum noise exceedances are between ground level and 5th floor level. Depending on distance and elevation of the NSR under consideration, the noise impact reduces by between 1 to 4 dB(A) for every 5 storeys.
Predicted unmitigated construction noise levels at the NSRs are shown in Table 7.7. It should be noted that the noise levels represent worst case scenarios, since the calculations assume that all of the available plant items for a phase of works are in use for 100% of the time. In practice this is unlikely to be the case as a number of plant items will operate sequentially with spatial constraints within the work site, and all equipment items would unlikely be operated at the same location. As will be seen later, these constraints are recommended as part of the noise mitigation control strategy (M3 and M4) at some critical NSRs.
During the construction of Pui To Road Grade Separation, adverse construction noise impacts would be likely at Tuen Mun Town Plaza Block 1 (N50) due to the limited buffer distances. Site clearance, pile cap construction, column and superstructure constructions all involve use of noisy Powered Mechanical Equipment. Other areas of significant noise impacts include Top Court (N46), Man Shing Building (N47), Kam Wah Garden (N48 and N49), Tuen Mun Town Plaza Block 2 (N51), Sun Court Podium (N53) and Tuen Mun Town Plaza (N55).
The affected floors would include low level, mid-level and high level floors. For N50 Tuen Mun Plaza Block 1, the noise exceedances in these floors are 13~16 dB(A), 10~12 dB(A) and 5~8 dB(A) respectively [27].
The worst affected NSRs would include the ground level and the 5th floor level, as the construction works would involve plant operation at an elevation.
The range of construction noise impacts would be 1 to 16 dB(A) exceeding the daytime criteria. The predicted worst NSRs include Tuen Mun Town Plaza Block 1 (N50).
Adverse construction noise impacts would be anticipated at the low-rise residential houses (N69 and N71), primarily during site clearance, piling and pile cap construction, column and superstructure construction. A maximum noise level of 90 dB(A) was predicted at the 2-storey residential house (N69 and N71) with exceedance of 15 dB(A) above daytime construction noise criterion.
The majority of NSRs that is likely to be affected include low-rise residential houses. The high-rise building blocks including Siu Tai House and Siu Ping House (N74 and N76) will also be affected. The affected floors of these NSRs would include low level floor, mid-level floor and high-level floor. The noise exceedances in these floors are 4~7 dB(A), 3~6 dB(A) and 1~4 dB(A) respectively [27].
Exceedances of up to 19 dB(A) at the key representative NSRs were predicted within this section of LRT Reserve Zone Extension. The impacted areas shall include Kung Yik She Secondary School (N35), Lynwood Court Block 10 (N38), Tin Shui Wai Area 105 Phase 1 Block 5 (N89), Tin Shui Wai Area 31 Phase 1 Blocks 2 & 3 (N106 and N107), Tin Shui Wai Area 30 Block 4 (N115), Tin Shui Wai Area 31 Phases 1 & 2 Primary Schools (N118 and N120), Tin Shui Wai Area 102 Phase 1 Block 4 (N123), Tin Shui Wai Area 102 Phase 5 Block 17 (N129), Tin Shui Wai Area 110 Phase 2 Block 11 (N137) and Tin Shui Wai Area 110 Phase 2 Block 10 (N138). Adverse construction noise impacts would be anticipated at Tin Shui Wai Area 31 Phases 1 & 2 Primary Schools (N118 and N120).
The affected flats would include NSRs at all floor levels. For the high-rise residential blocks N38, N89, N106, N107 and N115, the noise exceedances in low-level, mid-level and high level floors are 3~10 dB(A), 5~10 dB(A) and 3~7 dB(A) respectively.
The predicted noise levels show that unmitigated
construction activities are likely to give rise to adverse daytime noise
impacts at the majority of the NSRs in the vicinity of the proposed alignment,
and mitigation measures are therefore required. Noise emissions from construction sites could be minimised
by the following means:
· use of good site practices to limit noise emissions at the source;
· scheduling of construction works outside school examination periods in critical areas;
· use of “quiet PME” and working methods (M1);
· use of site hoarding as noise barriers (with careful design) to screen noise at ground level zone (M2);
· use of permanent, temporary and movable noise barriers (M2);
· delocalization of equipment and/or local reduction of the number of plant to be used on site, where practicable (M3); and
· limiting the operating time of construction equipment on site and use of smaller equipment (M4).
Based on the analysis of unmitigated impacts, the maximum allowable total sound power levels generated from plant items during daytime construction works (ie 0700 to 1900 hours) are derived, where maximum noise exceedance are predicted. The sound power level limits for the key representative NSRs are summarised in the table below.
|
NSR |
Description |
Activities in Each Construction Phase(1,2) |
||||||||||||
|
|
|
|
SCF |
LSC |
PIL |
PCC |
BF |
CLC |
SSC |
TRL |
OLC |
SRE |
RRE |
|
|
Worksite1- |
N46 |
Top
Court |
112 |
- |
112 |
112 |
112 |
112 |
112 |
112 |
112 |
112 |
112 |
|
|
Pui To Road |
N47 |
Man
Shing Building |
110 |
- |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
|
|
Grade Separation |
N48 |
Kam
Wah Garden Block 1 |
109 |
- |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
|
|
|
N49 |
Kam
Wah Garden Block 2 |
110 |
- |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
|
|
|
N50 |
Tuen
Mun Town Plaza Block 1 |
104 |
- |
104 |
104 |
104 |
104 |
104 |
104 |
104 |
104 |
104 |
|
|
|
N51 |
Tuen
Mun Town Plaza Block 2 |
111 |
- |
111 |
111 |
111 |
111 |
111 |
111 |
111 |
111 |
111 |
|
|
|
N53 |
Sun
Court Podium |
109 |
- |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
109 |
|
|
|
N55 |
Tuen
Mun Town Plaza Block 8 |
108 |
- |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
|
|
|
N200 |
San
Fat Estate |
110 |
- |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
110 |
|
|
Worksite2-LT1
Grade |
N64 |
2-storey
residential house |
120 |
- |
120 |
120 |
120 |
120 |
120 |
120 |
120 |
120 |
120 |
|
|
Separation |
N65 |
3-storey
residential house |
114 |
- |
114 |
114 |
114 |
114 |
114 |
114 |
114 |
114 |
114 |
|
|
|
N66 |
Care
Home for the Elderly |
122 |
- |
122 |
122 |
122 |
122 |
122 |
122 |
122 |
122 |
122 |
|
|
|
N68 |
2-storey
residential house |
125 |
- |
125 |
125 |
125 |
125 |
125 |
125 |
125 |
125 |
125 |
|
|
|
N69 |
2-storey
residential house |
108 |
- |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
|
|
|
N71 |
1-storey
residential house |
108 |
- |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
108 |
|
|
|
N72 |
2-storey
residential house |
126 |
- |
126 |
126 |
126 |
126 |
126 |
126 |
126 |
126 |
126 |
|
|
|
N73 |
You
Tze Tin Memorial College |
117 |
- |
117 |
117 |
117 |
117 |
117 |
117 |
117 |
117 |
117 |
|
|
|
N74 |
Siu
Tai House |
119 |
- |
119 |
119 |
119 |
119 |
119 |
119 |
119 |
119 |
119 |
|
|
|
N76 |
Siu
Ping House |
116 |
- |
116 |
116 |
116 |
116 |
116 |
116 |
116 |
116 |
116 |
|
|
Worksite3-
Tin Shui Wai Reserve Zone Extension |
N35 |
Shap
Pat Heung Rural Committee Kung Yik She Secondary School |
114 |
114 |
- |
- |
114 |
- |
- |
114 |
114 |
- |
- |
|
|
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