CONTENTS

 

1        Introduction

1.1     General

1.2     Project Background

1.3     Purpose and Approach of the EIA Study

1.4     Structure of this EIA Study Report

2        project description

2.1     Key Project Requirements

2.2     Project History and Site Selection

2.3     Project Characteristics and Site Location

2.4     Nearby Projects

2.5     Likely Future Environmental Conditions Without the Project

3        Air Quality impact assessment

3.1     Introduction

3.2     Relevant Guidelines, Standards & Legislation

3.3     Baseline Conditions and Air Sensitive Receivers

3.4     Construction Dust Impact Assessment

3.5     Mitigation Measures

3.6     Environmental Monitoring and Audit Requirements

3.7     Conclusions and Recommendations

4        Noise impact assessment

4.1     Introduction

4.2     Relevant Guidelines, Standards & Legislation

4.3     Noise Sensitive Receivers

4.4     Noise Environment at Peng Chau

4.5     Construction Noise Impact Assessment

4.6     Operational Noise Impact Assessment

4.7     Environmental Monitoring and Audit Requirements

4.8     Conclusions and Recommendations

4.9     References

5        Waste MANAGEMENT aSSESSMENT

5.1     Introduction

5.2     Legislation & Standards

5.3     Baseline Conditions & Sensitive Receivers

5.4     Assessment Methodology

5.5     Waste Types

5.6     Impact Assessment and Evaluation

5.7     Summary of Waste Materials Generated

5.8     Impact Mitigation & Residual Impact Assessment

5.9     Environmental Monitoring and Audit Requirements

5.10   Conclusions and Recommendations

5.11   References

6        water quality impact assessment

6.1     Introduction

6.2     Assessment Approach

6.3     Regulations, Standards and Guidelines

6.4     Baseline Conditions

6.5     Assessment Approach & Methodology

6.6     Impact Assessment & Evaluation

6.7     Impact Mitigation & Residual Impact Assessment

6.8     Environmental Monitoring & Audit

6.9     Conclusions and Recommendations

6.10   References

7        Ecology

7.1     Introduction

7.2     Assessment Approach

7.3     Regulations, Standards and Guidelines

7.4     Ecological Baseline

7.5     Impact Assessment & Evaluation

7.6     Impact Mitigation & Residual Impact Assessment

7.7     Environmental Monitoring & Audit Requirements

7.8     Conclusions & Recommendations

7.9     References

8        fisheries

8.1     Introduction

8.2     Assessment Approach

8.3     Applicable Regulations, Standards and Guidelines

8.4     Assessment Methodology

8.5     Fisheries Baseline

8.6     Impact Assessment & Evaluation

8.7     Impact Mitigation & Residual Impact Assessment

8.8     Environmental Monitoring & Audit Requirements

8.9     Conclusions & Recommendations

8.10   References

9        CULTURAL HERITAGE IMPACT ASSESSMENT

9.1     Introduction

9.2     Assessment Approach

9.3     Regulations, Standards and Guideline

9.4     Assessment Methodology

9.5     Baseline Conditions

9.6     Impact Assessment and Evaluation

9.7     Impact Mitigation & Residual Impact Assessment

9.8     Environmental Monitoring & Audit

9.9     Conclusions & Recommendations

9.10   References

10      Implementation Schedule of Recommended Mitigation Measures

10.1   Introduction

11      summary Conclusion & recommendations

11.1   Summary Conclusion of Technical Assessments

11.2   Key Recommendations

11.3   Summary of Environmental Outcomes

 

LIST OF FIGURES

Figure 2.1          Peng Chau Helipad Siting Options

Figure 2.2          Peng Chau Helipad – Site Location

Figure 3.1          Proposed Helipad Location and Environs

Figure 4.1          Representative Noise Sensitive Receiver Locations

Figure 4.2          Geographical Centres of Construction Activities

Figure 4.3          Approach and Departure Area and Surface Profile

Figure 4.4a        Index Plan for Cross Sections between NSR and Helipad

Figure 4.4b        Index Plan for Cross Sections between NSR and Flight Path

Figure 4.5a        Cross Sectional View for NSR to the Helipad (NSR1, NSR2, NSR3)

Figure 4.5b        Cross Sectional View for NSR to the Helipad (NSR4, NSR5, NSR6)

Figure 4.5c        Cross Sectional View for NSR to Flight Path (NSR3, NSR4)

Figure 4.5d        Cross Sectional View for NSR to Flight Path (NSR5, NSR6)

Figure 4.6          Illustration of Affected Area by Helicopter Noise

Figure 5.1          Cross Section of Helipad Footprint

Figure 5.2          EVA Footprint – Cross Section A

Figure 5.3          Helipad Footprint – Cross Section B and C

Figure 6.1          Frequency and Direction of Current Velocity at Peng Chau

Figure 6.2          Cumulative Spatial Extent of Construction Phase Mixing Zone

Figure 7.1          Ecology Assessment Area and Sensitive Receivers

Figure 7.2          Habitat Map of the Peng Chau Study Area

Figure 7.3          Habitat Photographs

Figure 8.1          Fisheries Areas of Peng Chau

Figure 9.1          Marine Geophysical / Marine Archaeology Survey Area and Sea Floor Features of Note

LIST OF TABLES

Table 2.1               Summary Matrix for Evaluation of Helipad Site Options & Alternatives

Table 2.2               Summary of Peng Chau Helipad Construction Programme

Table 3.1               Hong Kong Air Quality Objectives

Table 3.2               Annual Average Pollution Concentrations Recorded in Tap Mun (Year 2002)

Table 4.1               Recommended Construction Noise Levels (Non-restricted Hours)

Table 4.2               Area Sensitivity Rating Criteria

Table 4.3               Acceptable Noise Levels in Leq(5 min) dB(A)

Table 4.4               Helicopter Noise Standards for Planning Purposes

Table 4.5               Location of NSR Assessment Points in Peng Chau

Table 4.6               Noise Monitoring Results at Sea Crest Villa

Table 4.7               Powered Mechanical Equipment to be used for Construction of Helipad

Table 4.8               Construction Activities

Table 4.9               Predicted Construction Noise Levels Leq(30 min) dB(A) - Unmitigated

Table 4.10             Sound Power Levels for the Silenced Equipment

Table 4.11             Predicted Construction Noise Levels Leq(30 min) dB(A) – Mitigated

Table 4.12             Predicted Cumulative Construction Noise Levels Leq(30 min) dB(A) at NSR1

Table 4.13             Helicopter Noise Data – Airborne Helicopter with Lateral Movements

Table 4.14             Measured Lmax Noise Level of GFS Helicopters – Without Lateral Movements

Table 4.15             Helicopter Use for Peng Chau ‘Casevac’ Operations during years 2000 – 2004

Table 4.16             Worst-case Helicopter Noise Levels at NSRs during Helicopter Manoeuvring

Table 4.17             Worst-case Helicopter Approach / Departure Noise Levels at NSRs

Table 5.1               Material Import Requirements

Table 5.2               Summary of Construction Phase Waste Generation

Table 6.1               Relevant Water Quality Objectives for Southern WCZ

Table 6.2               Summary of Water Quality at ‘SM10’ between 1997 and 2001

 Figure 6.1             Frequency and Direction of Current Velocity at Peng Chau

Table 6.3               Predicted SS Elevation

Table 7.1               Representative Species in the Peng Chau Marine Benthic Community (CityU, 2002)

Table 7.2               Univariate Statistics for S. Peng Chau & Similar HKSAR Survey Areas (CityU, 2002)

Table 7.3               Habitat Types in the Assessment Area

Table 7.4               Categorisation of Benthic Cover and Substrate

Table 7.5               Rank Abundance of Pak Wan Sub-tidal Benthic Community

Table 7.6               Inter-tidal Survey Data for Pak Wan (BMT, October 2002)

Table 7.7               Butterfly Survey Data for Pak Wan, Peng Chau (BMT, 2002 & 2003)

Table 7.8               Bird Survey Data for Northwest Peng Chau (BMT, 2002 & 2003)

Table 7.9               Ecological Evaluation of the Sub-tidal Habitat

Table 7.10             Ecological Evaluation of the Sandy Shore (Beach) habitat

Table 7.11             Ecological Evaluation of the Hard Shore habitat

Table 7.12             Ecological Evaluation of the Coastal Scrub habitat

Table 7.13             Ecological Evaluation of the Secondary Woodland habitat

Table 7.14             Ecological Evaluation of the Developed / Disturbed Area

Table 7.15             Summary of Ecological Impacts

Table 8.1               Top Ten Ranked Adult Fish / Crustacean Families (from AFCD, 2003)

Table 8.2               Top Adult Fish / Crustacean Species by Weight from Peng Chau (AFCD, 1998)

Table 8.3               Production of Peng Chau Fisheries Areas (AFCD, 1998)

Table 8.4               Production Range for Fishing Methods at Peng Chau (AFCD, 2003)

Table 8.5               Commercial Value of Top Adult Fish Species around Peng Chau (AFCD, 1998; BMT, 2003).

Table 8.6               Common Fish Catch species at Northwest Peng Chau (BMT, 2003)

Table 10.1             Air Quality – Implementation Schedule of Recommended Mitigation Measures

Table 10.2             Noise – Implementation Schedule of Recommended Mitigation Measures

Table 10.3             Waste Management – Implementation Schedule of Recommended Mitigation Measures

Table 10.4             Water Quality – Implementation Schedule of Recommended Mitigation Measures

Table 10.5             Ecology – Implementation Schedule of Recommended Mitigation Measures

Table 10.6             Fisheries – Implementation Schedule of Recommended Mitigation Measures

 

LIST OF Appendices

Appendix 2.1     Visual Illustrations

Appendix 2.2     Construction Schedule

Appendix 2.3     Construction Schedule for DSD’s Sewage Treatment Works Upgrade

Appendix 4.1     Construction Equipment Inventory

Appendix 4.2     Construction Noise Calculation – Unmitigated

Appendix 4.3     Construction Noise Calculation – Mitigated

Appendix 4.4     Cumulative Construction Noise Calculation

Appendix 4.5     Helicopter Noise Measurement Points and Noise Levels

Appendix 4.6     Helicopter Noise Survey Report

Appendix 4.7     Helicopter Noise Calculations

Appendix 5.1     Historical Sediment Quality Monitoring Locations & Results at Peng Chau

Appendix 5.2     Sediment Classification Flow Chart

Appendix 5.3     Actual Sediment Sampling Locations within Helipad Footprint

Appendix 6.1     Summary of Sediment Quality for Routine Marine Sediment Quality Monitoring Station ‘SS5’ (1997 - 2000)

Appendix 7.1     Rapid Ecological Assessment (REA) Evaluation Framework

Appendix 7.2     Inter-tidal Survey Data for Pak Wan (BMT, April 2003)

Appendix 7.3     Marine Habitat Loss / Disturbance Calculations

 

1                    Introduction

1.1               General

1.1.1          In August 2002 BMT Asia Pacific Limited (BMT) was awarded the contract for Agreement No. CE 18/2002: Environmental Impact Assessment Study for Construction of Helipads at Peng Chau and Lamma Island / Investigation by the Civil Engineering Office, Civil Engineering & Development Department (CEDD). 

1.1.2          The Agreement requires the completion of Environmental Impact Assessment (EIA) studies for two proposed helipads: one at Peng Chau and one Yung Shue Wan, Lamma Island.

1.1.3          This Report presents the approach to and findings of the EIA study for the proposed Peng Chau helipad, and follows the requirements of Environmental Impact Assessment Study Brief No. ESB-091/2001.

1.2               Project Background

1.2.1          The Project involves the construction and operation of a permanent helipad at Peng Chau, and is ‘designated’ under Item B.2, Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO) by virtue of being: “A helipad within 300m of existing or planned residential development”.  Accordingly, an Environmental Permit is required for the Project.

1.2.2          The Project has been planned and managed in-house by the Land Works Division of CEDD. Construction works are to be completed by contractors under CEDD’s supervision.  CEDD will hand over the helipad to the management department (yet to be determined) upon its commissioning.

1.2.3          The helipad is solely required for transporting Peng Chau residents to urban areas for medical treatment in emergency situations, and is not for commercial use.  The current Peng Chau helipad is located on a soccer pitch near Tai Lung Tsuen and is the only landing site for the island.  This site, located at the top of a hill, is still being used by Government Flying Service (GFS) for casualty evacuation (‘casevac’) operations but is not considered ideal on flight safety grounds, as the site constitutes a confined area – being surrounded by tall lighting posts.

1.2.4          Furthermore, the Tai Lung Tsuen landing site is only accessible by climbing long stairs. Vehicle access is impossible, and so the current helipad is very inconvenient for paramedics who presently must carry patients up the stairs by foot.  The path to the existing landing site cannot be upgraded without significant reconstruction works, including partial demolition of village property.  As such, the anticipated environmental and community impact associated with such upgrade works would be considerable.  In view of the present situation, the Home Affairs Department (HAD) had commissioned CEDD to construct a permanent helipad to serve the local community.

1.2.5          A full description of the Project is presented in Section 2 of this Report.

1.3               Purpose and Approach of the EIA Study

1.3.1          The purpose of this EIA Study is to provide information on the nature and extent of environmental impacts arising from the Project and other concurrent works. This information will contribute to decisions by the Director of the Environmental Protection Department (EPD) on:

(i)             The overall acceptability of any adverse environmental consequences that are likely to arise as a result of the proposed Project;

(ii)           The conditions and requirements for the detailed design, construction and operation of the proposed Project to mitigate against adverse environmental consequences wherever practicable; and

(iii)          The acceptability of residual impacts after implementation of proposed mitigation measures.

1.3.2          Satisfying the aims of the EIA Study has been managed by achieving a number of more specific objectives as listed in the EIA Study Brief.  The objectives of the EIA study are to:

(i)             Describe the proposed Project and associated works together with the requirements for carrying out the proposed Project;

(ii)           Consider alternative design and construction method(s) for the proposed Project and to compare the environmental benefits and disadvantages of each of the method(s) and design in selecting a preferred one;

(iii)          Identify and describe elements of community and environment likely to be affected by the proposed Project and/or likely to cause adverse impacts to the proposed Project, including natural and man-made environment;

(iv)         Identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;

(v)           Identify and quantify potential losses or damage to aquatic organism and natural habitats and to propose measures to mitigate these impacts;

(vi)         Identify and quantify potential losses or damage to flora, fauna and natural habitats and to propose measures to mitigate these impacts;

(vii)        Propose the provision of mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the proposed Project;

(viii)      Identify, predict and evaluate the residual (i.e. after practicable mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operation phases of the proposed Project in relation to the sensitive receivers and potential affected uses;

(ix)         Identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the proposed Project which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;

(x)           Investigate the extent of the secondary environmental impacts that may arise from the proposed mitigation measures, and to identify the constraints associated with the mitigation measures recommended in the EIA study as well as the provision of any necessary modification;

(xi)         Design and specify environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.

1.4               Structure of this EIA Study Report

1.4.1          The EIA Report is divided into a total of 10 sections.  Following this Section 1, Introduction, the Report is organised as follows:

·          Section 2 – Project Description

·          Section 3 – Air Quality Assessment

·          Section 4 – Noise Assessment

·          Section 5 – Waste Management Assessment

·          Section 6 – Water Quality Assessment

·          Section 7 – Ecological Assessment

·          Section 8 – Fisheries Assessment

·          Section 9 – Cultural Heritage Assessment

·          Section 10 – Implementation Schedule of Recommended Mitigation Measures

·          Section 11 – Summary Conclusion & Recommendations.

1.4.2          The respective assessments for each technical discipline follow the appropriate requirements as set out in the Technical Memorandum on Environmental Impact Assessment Process (EIA-TM).

1.4.3          For each section, all Figures referred to are at the back of the appropriate section for ease of reference, while all Appendices are together at the back of the EIA Report.

 

2                    project description

2.1               Key Project Requirements

2.1.1          The fundamental Project requirements are the construction of an easily accessible and permanent helipad and an associated Emergency Vehicle Access (EVA) link with sufficient width to allow free movement of an ambulance.  The Fire Services Department has requested a 4.5-metres wide EVA for the Peng Chau helipad, while the GFS has confirmed that a round helipad of 25 metres diameter is sufficient for helicopter operations.

2.1.2          The helipad is solely intended for emergency use and associated essential ‘casevac’ training flights, and will not be used for commercial operations. As such, helipad use will be intermittent, with no fixed flight schedule. The primary considerations for helipad development are flight operation safety and its accessibility by ground emergency vehicles from the Peng Chau Clinic in emergency situations. The helipad must also be operable and accessible at all times.

2.1.3          According to the GFS Helipad Specification Guidelines, the guiding factors for siting a ‘surface-level helipad’ are as follows:

a)             The design and the location should be such that downwind operations are avoided and crosswind operations are kept to minimum to maximise helicopter manoeuvrability and operational safety.  It should have two approach surfaces, separated by at least 150 degrees (i.e., a minimum flight path angle of 150 degrees).

b)            The site should be conveniently situated as regards ground transport access mainly for emergency service (e.g. ambulance, fire engines) and adequate vehicle parking facilities.

c)            The ambient noise level should be considered near noise sensitive receivers, and especially in relation to areas below the helicopter approach / departure path(s). This means that the helicopter flight path should be situated away from residential areas as far as is practicable, and for this reason the flight path for the proposed Peng Chau Helipad will approach and depart from the proposed helipad across the sea.

d)            Ground conditions beneath the take-off climb and approach surfaces should permit safe landings in the event of engine failure or forced landings during which injury to persons on the ground and damage to property is minimized.

e)             Consider, and assess with flight tests if necessary, the potential for and effects of eddies and turbulence that may be caused by any large structures close to the proposed helipad.

f)             Consider the presence of high terrain or other obstacles, especially power lines, in the vicinity of the proposed site that may pose a potential hazard.

2.1.4          As information on the usage frequency of the proposed Peng Chau Helipad is critical for accurate operational phase impact assessment, relevant flight data from GFS for the 2000 – 2004 period has been reviewed (Section 4.6 refers).  Data for the year 2002 represents the greatest number of casevac flights in recent years, and so has been used as a basis for the impact assessment.

2.1.5          Information on possible future changes in the size of the resident population is also important, and the Notes of the draft Peng Chau OZP No. S/I-PC/6 (dated April 15th 2005) estimate a planned population of about 6,200 persons: up 1% from the population of around 6,130 persons estimated from the 2001 Census. Given that the GFS data for the year 2002 already represents a worst-case scenario for determining casevac flight frequency, this small population increase is considered insignificant.

2.1.6          There is no specific data available on tourist vists to Peng Chau, indicating that the island is not considered a significant tourist destination.

2.2               Project History and Site Selection

Identification of Options / Alternatives

2.2.1          With reference to Clause 3.3 of the EIA Study Brief, a number of construction and operational scenarios have been considered for the Project, with the preferred option selected accordingly.  Consideration has been given to alternatives for:

·          Helipad location and EVA link alignment;

·          Project Design and construction methods; and

·          Helicopter approach and departure paths.

2.2.2          As regards potential helipad siting options, three potential options identified through a site selection exercise initiated in 1997 by the then District Planning Office (DPO) for Sai Kung & Islands (now DPO for Lantau & Islands) were taken forward for consideration, namely Options A1, B1 and C.

2.2.3          A further ten site options / alternatives were identified under this Study for investigation. However, two of these additional ten sites – both located beyond the immediate Study Area (at east Peng Chau (Tung Wan) and southeast Peng Chau) – were found to be either of insufficient helicopter manoeuvring room or with unsuitable approach / departure paths and so were not taken forward for detailed consideration.

2.2.4          The characteristics of the eleven options / alternatives that were taken forward for more detailed consideration are summarised below.  Figure 2.1 displays the locations of the eleven sites.

Option A: Alternative A1 - Pak Wan (Marine EVA)

2.2.5          The proposed ‘Option A: Alternative A1’ is situated on the north coast of Peng Chau, and would require construction of approximately 150 metres of new EVA along the natural existing rocky / sandy coastline from the junction of Peng Lei Road with the Tai Lei bridge crossing. The helipad would be constructed slightly offshore.

2.2.6          The proposed site is immediately adjacent to a natural rock wall that would provide some noise shielding from the construction and operation of the helipad.

Option A: Alternative A2 - Pak Wan (Land EVA)

2.2.7          The proposed ‘Option A: Alternative A2’ would access the same helipad as for ‘Option A: Alternative A1’ but by way of an inland coastal EVA that would follow the approximate alignment of the existing Pak Wan footpath and would thereby largely avoid disturbing the natural shoreline.

2.2.8          The start of this alternative EVA would also be from the Peng Lei Road / Tai Lei bridge crossing junction, and is also about 150 metres long.

Option B: Alternative B1 - Pei Lei

2.2.9          The proposed ‘Option B: Alternative B1’ would involve developing the helipad on top of the small islet of Pei Lei, off the northeast coast of Tai Lei.  As the Pei Lei islet is on rocky ground, it was assumed that the construction of this alternative would require rock drilling / blasting activities to form a level platform for use by the helicopter.

2.2.10      There would also be a need to develop approximately 100m of EVA from the Tai Lei end of the bridge crossing, of which some 70m could be developed on existing formed land with the re-provisioning of a landscaped area.  The remaining 30m of EVA would be developed by concrete on top of small diameter mini bored piles.

2.2.11      It was noted that there is a hard coral community of some ecological conservation value around Pei Lei that would need to be considered should there be any development of this option.

Option B: Alternative B2 - Pei Lei Southwest

2.2.12      The proposed ‘Option B: Alternative B2’ site would involve developing the helipad on a raised platform supported by small pre-bored mini piles on the relatively flat southwestern edge of Pei Lei. This alternative could avoid directly disturbing coral communities of ecological and conservation value around Pei Lei.

2.2.13      As with ‘Option B: Alternative B1’, there would be the need to construct an 80m long EVA link from the Tai Lei end of the bridge crossing, although most of this length can be developed relatively easily through re-provisioning of the existing landscaped area at the east of Tai Lei.

Option C – Kam Peng Estate

2.2.14      The proposed ‘Option C’ site is located to the west of Kam Peng Estate.  As the land has been reclaimed, the construction works required would be relatively minor.  However, this site is in close proximity to nearby residences.

Option D – Tai Lei South

2.2.15      The proposed ‘Option D’ site is located at the southern site of Tai Lei Island beside the existing Peng Chau Sewage Treatment Works (STW). The Drainage Services Department (DSD) is planning for an extension of the STW under which a submarine outfall would be constructed. Through liaison with DSD, it was determined that the alignment of the planned effluent outfall could still leave sufficient space for the development of a helipad at this location.

2.2.16      The helipad would be situated on the existing land between the STW and the seawall. It is required to extend the southern side of the landing area by about 15 metres to meet the minimum helipad size requirement.  The EVA can be developed on existing formed land.  As there are also coral communities of ecological conservation value adjacent to the ‘Option D’ site, these need to be considered should there be any development of this option.

Option E – Pak Wan

2.2.17      The ‘Option E’ site was proposed to minimise the potential loss of natural shoreline, and hence potential water quality, ecology and fisheries impacts, as compared with ‘Option A’ site.  The helipad would be situated at a similar location to the ‘Option A’ site but closer to the existing Tai Lei bridge crossing so that only about 50 metres of EVA would be required.  However, this site cannot take advantage of the noise shielding effect of the rock wall near ‘Option A’ site and so noise impacts to adjacent residences would be correspondingly greater.

Option F – Pak Wan Reclamation Area (Open Space)

2.2.18      The proposed ‘Option F’ site is an open space at the north end of the Pak Wan reclamation area.  It was proposed to use part of the vacant area as a helipad site. As with the ‘Option C’ site, there are residential buildings nearby that would be particularly sensitive to helicopter noise.

Option G – Works Area of Highways Department on Tai Lei

2.2.19      The proposed ‘Option G’ site is currently used as a works area by a Highways Department (HyD) contractor and liquefied petroleum gas (LPG) cylinder storage area.  If the site was to be adopted, an alternative site would need to be provided for a new LPG storage facility.

Option H – Existing Small Pier on Tai Lei

2.2.20      This proposed ‘Option H’ site comprises the existing small pier on the southern side of Tai Lei Island, primarily used for the delivery of LPG cylinders and other goods.  The size of the pier deck has to be enlarged to comply with the minimum size requirements of the helipad.

2.2.21      There are also coral communities of ecological conservation value adjacent to the ‘Option H’ site that would need to be considered should there be development at this site.

Option I – Pak Wan (EVA East Extension)

2.2.22      This proposed ‘Option I’ helipad site would involve an eastwards extension to the ‘Option A: Alternative A1’ EVA by approximately 70 metres.  The extended EVA would pass along a sandy beach and around a ‘Coastal Protection Area’, but would allow the helipad to be located beyond the helicopter noise impact zone.

Construction Methods

2.2.23      Three construction methods for forming the helipad platform and the EVA link have been considered and these are briefly summarized as follows:[*]

·        The dredge and reclaim method would require dredging of marine sediment to a suitable depth to allow construction of a stable foundation, followed by deposition of filling materials up to the required platform level.

·        Small diameter pre-bored piling method involves sinking a casing through the substrate and removing the material within.  Concrete is then poured into the casing to form the pile. A platform structure is then constructed on top of the piles.

·        Percussive piling method involves driving steel piles into the bedrock. As the piles are driven through to the bedrock, sediments are laterally displaced without the need for dredging or excavation. A platform is constructed similarly as for the pre-bored piling method.

Evaluation of Options / Alternatives

2.2.24      Under the broader remit of the Assignment, the Consultants established a framework based on the basic principles of the EIA process that collectively aim to protect the environment through prevention.[†]

2.2.25      The evaluation framework comprised an initial assessment, mainly on environmental issues, through which environmental impacts were predicted through joint consideration of helipad location and construction method / programme.  This was followed by a Value Management (VM) exercise that involved consultation with the local community and other stakeholders at an early stage of the Project and before detailed technical assessment had been undertaken. The VM exercise  also took other non-environmental evaluation criteria, including time-frame, engineering feasibility, project cost, site availability, land ownership and community / social impacts into consideration.

2.2.26      The key community concerns identified through the consultation meetings and the VM exercise are listed below (in order of importance):

·         Operational safety – the safety of the helicopter crew, passengers and the nearby community during helicopter activity were the main concern.

·         Time frame – site availability and the speed of construction was raised as important factors due to the fact the helipad is for emergency casualty evacuation.

·         Direct ground access – given the inconvenience of the existing helipad, proximity to and availability of direct and uninterrupted access to the Peng Chau Clinic is another issue of key concern.

2.2.27      Cost is another factor to be considered as it may indirectly affect the project delivery schedule. If the project cost exceeds the available budget ceiling, a more lengthy funding allocation exercise will be required that will delay project development.

2.2.28      In accordance with ETWB Technical Circular (Works) No. 13/2003 on “Guidelines and Procedures for Environmental Impact Assessment of Government Projects and Proposals”, regular consultation has also been conducted with EPD and the local District Council throughout the duration of the EIA Study.

2.2.29      A summary of the helicopter site option evaluation in relation to environmental benefits, dis-benefits and other key non-environmental considerations (e.g., access and safety issues) is presented in Table 2.1.  Elaboration on the factors affecting site selection is provided in the following paragraphs.

2.2.30      For the ‘Option A: Alternative A2’ site, consideration had been given to combining the EVA construction works with those for the Pak Wan footpath.  However, the result of the assessment and evaluation exercise indicated that this approach would give rise to a range of unacceptable environmental impacts. In particular:

·         Widening the footpath to 4.5m wide to cater for the need of the EVA would require slope cutting some 3 metres into the natural hillside along the 150m long EVA. Assuming that the slope faces along the EVA are very stable rock and can be formed vertically to ~3m height, there would be a loss of at least 500m2 of natural vegetation. There would also be a need to form a vertical strip of engineered slope some 3m high and 150m long across the middle of the hillside parallel to the coastline.

·         The elevation of the footpath is at approximately 14mPD at its closest point to the proposed helipad. The helipad would be built to a final elevation of 5.15 mPD.  In order to link up the EVA with the helipad to match the level difference while satisfying the maximum allowable gradient for use of the emergency vehicles, the length of the EVA has to be extended and the helipad would need to be located further offshore.  Both requirements would increase the scale of the project and associated environmental impact potential.

2.2.31      The ‘Option B’ (both Alternatives B1 and B2) and ‘Option D’ sites were considered environmentally unacceptable, as they are too close to the ecologically sensitive coral communities that may be disturbed by sediment release during construction. The possible shading effect from the helipad platform could also adversely affect coral growth and survival.  These three options would also give rise to a helicopter noise impact at the Sea Crest Villa Noise Sensitive Receiver (NSR) under normal operating conditions.

2.2.32      The ‘Option C’ and ‘Option F’ sites would give rise to unacceptable safety concerns and helicopter noise impacts due to their close proximity to built areas and infrastructure nearby.  Similarly, the ‘Option E’ site –, as the closest to Sea Crest Villa – would generate unacceptable helicopter noise impacts on residents.

2.2.33      The ‘Option G’ and ‘Option H’ sites are not acceptable due to safety concerns over relocating the existing LPG storage / handling areas, while a helipad at either of these sites would also generate a helicopter noise impact at Sea Crest Villa under normal operating conditions.

2.2.34      As presented in more detail under sub-section 4.6, the coastal cliff adjacent to the Option A: Alternative A1’ location effectively shields the Sea Crest Villa NSRs from helicopter ‘manoeuvring’ noise.  This location is also sufficiently distant from Sea Crest Villa and other NSRs such that no helicopter ‘approach’ noise impacts are predicted during normal operations when the preferred ‘Eurocopter EC 155B1’ type helicopter is in use.

2.2.35      Helicopter ‘approach’ noise levels are predicted to reach up to 88dB(A) at Sea Crest Villa on occasions when the preferred ‘EC 155B1’ type helicopter is not available for use, and the ‘Super Puma AS332 L2’ type helicopter is required. However, the impact duration is predicted to last 5-10 seconds while the impact frequency is predicted to be just once approximately every 12 days.

2.2.36      Consideration was given to implementing direct and indirect mitigation measures to satisfy the 85dB(A) helicopter noise standard. It was found that if direct mitigation measures were pursued, involving relocation of the helipad further 70m to the east to eliminate residual helicopter noise generated by the ‘Super Puma’ type helicopter (i.e., ‘Option I’), such relocation would infringe upon an area zoned “Coastal Protection Area” on the draft Peng Chau OZP No. S/I-PC/6 and therefore give rise to adverse landscape impacts, increased waste handling, habitat loss and water quality impacts.

2.2.37      As the helipad is intended for emergency use there is no fixed flight schedule.  Accordingly, the use of indirect mitigation, such as improved window glazing and installation of air conditioners, was not considered practicable due to the short impact duration (< 10 seconds) and unpredictable timing of helicopter operations at the proposed helipad.

2.2.38      Overall, in addition to consideration of the residual helicopter noise impact on the local community as mentioned in above paragraphs, as the residual helicopter noise impact is not predicted to cause significant adverse long-term effects on the local community, development at the ‘Option A: Alternative A1 helipad location is preferred.  It is also noted that the noise impact due to helicopter manoeuvring at the existing helipad is estimated to adversely affect over 100 residential buildings.  Furthermore, the noise level at Sea Crest Villa from existing helicopter flight is 92 dB(A) when the ‘Super Puma’ is in operation and 89 dB(A) when the ‘EC 155B1’ is operational [sub-section 4.6 refers]. These levels are above the permissible noise standard of 85dB(A).

2.2.39      Reclamation was selected as the preferred construction method by virtue of the shorter time frame required for development in the absence of any significant adverse construction phase environmental impacts. Percussive piling would give rise to significant construction noise impacts due to the proximity of the works area to residences at Sea Crest Villa, while the main disadvantage of mini pre-bored piling is the slow rate of construction and hence delay in availability of the project to the local community.  The footprints of the helipad and EVA are small due to the shallow water depth, and hence the scale of the reclamation is relatively minor.  Reclamation also ensures there is no adverse construction noise impact at Sea Crest Villa [Section 4 refers].

Design Refinements to the Preferred Option

2.2.40      Consideration has been given to means by which the design could be refined to minimise the scale and duration of the works, and hence avoid or reduce the environmental impact potential. This approach of proactive avoidance and minimisation through design takes precedence over impact mitigation.

2.2.41      During the course of the study the following measures have been taken to refine the project design with a view to avoiding potential impacts:

·        The elevation of the helipad and EVA have been lowered as far as practicable in order to minimize their footprint, and hence the disturbance to the affected coastal waters.

·        The sea-facing sloping boulder wall has been designed to a steeper gradient, resulting in a reduction in the size of the foundation.

·        The construction sequence shall be optimised to avoid cumulative construction noise effects with works for the proposed upgrading works of the Peng Chau Sewage Treatment Works.

2.2.42      In addition, during the detailed design stage of the Project the alignment of the EVA shall be further refined to make it as close to the existing cliff-face as is practicable in order to minimise marine-based works and the loss of shallow sub-tidal habitat.

Operational Considerations

2.2.43      Helicopter noise is the main environmental concern during operation of the helipad. It is predicted that there would be residual noise impact of 3 dB(A) at Sea Crest Villas under the worst-case scenario, compared with the existing worst-case scenario exceedance of the noise criterion of 7 dB(A).  Based on worst-case GFS data for ‘casevac’ operations at Peng Chau, the predicted frequency of the residual impact is approximately once every 12 days.  The impact duration would last for not more than 5-10 seconds per event.  A number of issues have been considered in this regard, and are discussed in greater detail in sub-section 4.6. They include:

Helipad distance from the built environment

2.2.44      It has been predicted that the helicopter flight noise impact ‘zone’ for the ‘Super Puma’ type helicopter is 221 metres [para. 4.6.19 refers]. Given the hilly nature of the topography at north and south Peng Chau and the relatively densely populated central isthmus that needs to be protected from helicopter noise impacts as far as is practicable, there are no suitable land-based helipad options. On the other hand, there is need to minimize the travelling time from the Clinic to the helipad.  A suitable balance must be struck between these conflicting requirements.

2.2.45      Of all the Options / Alternatives considered, ‘Option A: Alternative 1’ offers the best noise environment as it is relatively remote from the built environment, while a natural rocky cliff-face will effectively shield Sea Crest Villa – the nearest Noise Sensitive Receiver – from adverse helicopter manoeuvring noise impacts.  There will be no adverse helicopter noise impact under normal operating conditions.

Helicopter Type

2.2.46      Consideration has been given to use of helicopter types generating lower noise levels for casualty evacuation operations.  However, GFS has confirmed that at present only the two helicopter types that have been assessed in this EIA Report (i.e., the ‘Eurocopter EC155 B1’ and ‘Eurocopter Super Puma AS332 L2’) are available for such operations.

2.2.47      For operational considerations, the GFS would not be able to exclude the ‘Super Puma’, the noisier of the two types, from using the helipad although the GFS has agreed to give priority to the quieter ‘EC155 B1’ type helicopter for ‘casevac’ operations wherever practicable. This approach also follows the trend of current usage of the two helicopter types in Peng Chau.  As only one helicopter would be able to operate at the helipad at any one time, no cumulative helicopter noise effects will be generated. During the years 2003 and 2004, GFS has only used the smaller and quiter EC155 B1 type helicopter for night-time casevac operations and GFS has advised that this usage trend is expected to continue.


Table 2.1          Summary Matrix for Evaluation of Helipad Site Options & Alternatives

Option / Alternative

Location *

Key Environmental Benefit(s)

Key Environmental Dis-benefit(s)

Other Key Considerations      (e.g., safety & access)

Conclusion

A1

Pak Wan – marine EVA

·    No helicopter manoeuvring noise impact during any operations.

·    No helicopter flight path noise impacts under normal operations.^

·     Helicopter flight path noise impact from use of ‘Super Puma’ type helicopter.

·     Easy access from Clinic.

·     No flight safety concerns.

Residual flight path noise impact from Super Puma, but no helicopter noise impact under normal operations.

A2

Pak Wan – land EVA

·    No helicopter flight path noise impacts under normal operations.

·     Potential ecological impact from necessary slope works.

·     Manoeuvring noise impact from both helicopter types and flight path noise from ‘Super Puma’.

·     Easy access from Clinic, although steep slopes to navigate to helipad.

·     No flight safety concerns.

Potential ecology impact from necessary EVA construction / slope works, and residual manoeuvring noise impacts for both helicopter types.

B1

Pei Lei

·    Minimal construction works.

·     Potential impacts on hard corals from construction works.

·     Helicopter flight path and manoeuvring noise impact.

·     Easy access from Clinic.

·     No flight safety concerns.

Potential adverse impacts on hard corals, and likely residual helicopter noise impact under normal operations.

B2

Pei Lei Southwest

·    Minimal construction works.

·     Potential impacts on hard corals from construction works and shading effect of EVA & Helipad.

·     Helicopter flight path and manoeuvring noise impact.

·     Easy access from Clinic.

·     No flight safety concerns.

Potential adverse impacts on hard corals, and likely residual helicopter noise impact under normal operations.

C

Kam Peng Estate

·    No significant construction phase impacts (land already formed).

·     Significant helicopter flight path and manoeuvring noise impact on nearby residences.

·     Best access from Clinic.

·     Helicopter flight safety concerns due to proximity to built-up area.

No construction phase concerns, but likely significant residual helicopter noise impacts under normal operations. Unacceptable flight safety concerns.

D

Tai Lei South

·    Minimal construction works.

·     Potential impacts on hard corals from construction works.

·     Helicopter flight path and manoeuvring noise impact.

·     Easy access from Clinic.

·     No flight safety concerns.

Potential adverse impacts on hard corals, and residual helicopter noise impact under normal operations.

E

Pak Wan

·    No significant construction phase impacts.

·     Significant helicopter flight path and manoeuvring noise impacts on nearby residences.

 

·     Easy access from Clinic.

·     Some flight safety concern due to proximity of Sea Crest Villa.

Likely significant residual helicopter noise impacts under normal operations, and flight safety concerns.

F

Pak Wan Reclamation (Open Space)

·    No significant construction phase impacts (land already formed).

·     Significant helicopter flight path and manoeuvring noise impact on nearby residences.

·     Best access from Clinic.

·     Helicopter flight safety concerns due to proximity to built-up area.

Likely significant residual helicopter noise impacts under normal operations. Unacceptable flight safety concerns.

G

Works Area of Highways Department on Tai Lei

·    No significant construction phase impacts (land already formed).

 

·     Helicopter flight path and manoeuvring noise impact.

·     Easy access from Clinic.

·     Need to reprovision LPG storage / handling area, otherwise no flight safety concerns.

Likely significant residual helicopter noise impacts under normal operations.

H

Existing Small Pier on Tai Lei

·    No significant construction phase impacts.

 

·     Helicopter flight path and manoeuvring noise impact.

·     Easy access from Clinic.

·     Need to reprovision LPG storage / handling area, otherwise no flight safety concerns.

Likely significant residual helicopter noise impacts under normal operations.

I

Pak Wan (EVA East Extension)

·    No helicopter manoeuvring or flight path noise impact.

 

·     Extended EVA will encroach into zoned “Coastal Protection Area” (CPA).

·     Easy access from Clinic.

·     No flight safety concerns.

The extended EVA on to the ‘CPA’ zone would create a significant adverse landscape impact.

Notes: * Figure 2.1 refers.           ^ Normal operation refers to the use of EC155 B1 type helicopter.


Helicopter Flight Path

2.2.48      The flight path is necessarily constrained by the flight safety requirements of GFS. The GFS guideline states that a surface level helipad should have two approach surfaces extending from the helipad.  In plan view, the centreline of the two flight paths should ideally be separated by at least 150 degrees so that should wind conditions impose constraints on flight safety (para 2.1.3(a) refers) there is always one other option for safe helicopter approach / departure.

2.2.49      It was determined that a flight path separation angle of 150 degrees would adversely affect all residences at Sea Crest Villa. With the agreement of GFS, the angle of separation between the two flight paths for the ‘Option A: Alternative A1’ site has been reduced to 115 degrees [Figure 4.3 refers]. The re-aligned helicopter flight path will increase the distance between the noise source (helicopter) and the noise sensitive receiver (residential area) so that helicopter approach noise generated by the ‘EC155 B1’ type helicopter can be reduced to within the 85dB(A) guideline at all noise sensitive receivers.

2.2.50      There will be a residual helicopter noise impact when the ‘Super Puma AS332 L2’ helicopter is used although this helicopter type is not frequently used.

2.3              Project Characteristics and Site Location

2.3.1          The Project involves the construction of a helipad by the ‘dredge and reclaim’ method in shallow coastal waters of 2-3 metres depth at Pak Wan, northwest Peng Chau.  The project will be constructed off a natural, predominantly rocky coastline.  The project location was selected after detailed consideration of the operational requirements and environmental impact potential of developing the Project at each of thirteen site locations. With reference to the current statutory Peng Chau Outline Zoning Plan (No. S/I-PC/6), the proposed site is within a “Government, Institution or Community” (“G/IC”) zone and has been identified as a possible helipad. According to the Notes of the OZP, “Helicopter Landing Pad” is a Column 2 use that may be permitted with or without conditions on application to the Town Planning Board.

2.3.2          The helipad deck will be located approximately 10 metres from the back of the Pak Wan shore (i.e., existing land).  An EVA will be constructed along the natural shoreline to link the proposed helipad with the existing EVA located adjacent to Sea Crest Villa. The works contractor shall install a standard 2.4m high solid corrugated metal hoarding along the Peng Lei Road site boundary, opposite to Sea Crest Villa, to fence the site and with the effect of also avoiding adverse visual impacts on pedestrians. Figure 2.2 shows the site location, while Appendix 2.1 presents a visual illustration of the Project.

2.3.3          The site location was selected after due consideration of the operational requirements and environmental impact potential of constructing and operating the Peng Chau helipad at each of eleven site locations. Specific Project details are as follows:

·        Approximately 14,000m3 of fine to coarse marine sand will need to be dredged.

·        The EVA link will be about 150 metres long and 4.5 metres wide.

·        The helipad will have a diameter of 25 metres.

·        The EVA link and helipad surfaces will be formed to a height of approximately +5.0 mPD.

·        Wave deflectors will be installed around the helipad to enhance operational safety.

·        An off-site works area (including site office) to be located on existing vacant land immediately south of Sea Crest Villa that will be required for about 2 years, from December 2005. No off-site pre-casting works are anticipated.

2.3.4          The construction programme can be broadly summarised as presented by Table 2.2.

Table 2.2     Summary of Peng Chau Helipad Construction Programme

Construction Activity

Construction Period

Site Clearance

Dec 2005 – Jan 2006

Reclamation

Feb 2006 – Sept 2006

Construction of Helipad

Jan 2006 – Nov 2006

Construction of EVA

Jul 2006 – Nov 2006

 

2.3.5          Further details of the construction works are presented in Section 4, while the full construction programme is presented in Appendix 2.2.

Landscape Treatment

2.3.6          Clause 3.4.8 of the ESB that requires the provision of landscape design proposals.  On the advice of PlanD, it is proposed that vegetation cover be established beside the junction of the proposed new EVA with the existing Peng Lei Road, opposite the low-rise Sea Crest Villa residential development.  This area is the only part of the proposed EVA alignment that will be visible to the general public from and occupants of some of the middle and upper floor residences at Sea Crest Villa.  The coastal section of the proposed EVA comprises a natural vertical cliff face that does not require landscape treatment, while this section of the EVA and the actual helipad will be exposed to seawater splash where terrestrial vegetation cannot be established.  Hard landscaping measures have been proposed in these areas with the sensitive design of a sloping boulder seawall (Figure A2.1b and Figure A2.1c in Appendix 2.1 refer).

2.3.7          For the soft landscaping works, it is proposed that the area immediately west of the EVA at the Peng Lei Road junction and the strip between the coastal EVA and the foot of the cliff be hydroseeded with a commercially available mix of grass seeds.  A suitable composition of such a mixture that is currently being applied for hydroseeding works for CEDD’s Fill Bank at Tseung Kwan O Area 137 includes:

·          Carpet Grass (Anoxopus compressus): 5 g/m2

·          Bermuda Grass (Cynodon dactylon): 10 g/m2

·          Bahia Grass (Paspalum notatum): 10 g/m2

·          Mulch: 200 g/m2

·          Fertilizer (NPK 15:15:15): 100 g/m2

2.3.8          The location of the proposed hydroseeding is illustrated on Figure A2.1a and covers an approximate area of 100 m2.

2.3.9          Given the presence of a fairly diverse vegetation community at northwest Peng Chau, including a range of native trees and shrubs, it can be expected that natural colonisation of the hydroseeded area will occur in time, thereby adding to the 'greening' effect in the area.

2.4              Nearby Projects

2.4.1          Other projects identified in the vicinity that require consideration for the purposes of identifying and assessing as necessary the potential for cumulative effects are as follows:

Peng Chau Sewage Treatment Works Upgrade

2.4.2          The construction of DSD’s Peng Chau Sewage Treatment Works (STW) Upgrade is scheduled to commence in mid-2005 and is tentatively scheduled for completion by the end of 2007.  In addition to DSD’s further advice, the associated marine works are tentatively scheduled from August 2005 to April 2006, although the programme is still under vetting.  The latest agreed construction programme for the STW Upgrade project and DSD’s further information are presented in Appendix 2.3.

2.4.3          As the STW upgrading works may be implemented in parallel with the helipad project, the potential for, and magnitude of, cumulative impacts have been assessed in detail using a standard calculation based on the Gaussian theory, as presented in the following sections.

Drainage Improvement Works at Peng Chau

2.4.4          DSD is currently implementing a sewerage improvement scheme, mainly in the centre of Peng Chau town but also involving some works within the helipad project boundary.  It has been confirmed with DSD that the overall works are scheduled for completion in early / mid 2005, while the portion within the Peng Chau helipad project boundary – involving mains upgrade and construction of a pumping station – was completed in 2004.  As such, these works will not lead to any cumulative effects.

2.5              Likely Future Environmental Conditions Without the Project

2.5.1          Without the Project the existing helipad site on a hard surface soccer pitch located atop a hill near Tai Lung Tsuen will continue to be used.  In addition to flight safety concerns (para. 1.2.3 refers) and access difficulty (para. 1.2.4 refers), use of the existing helipad will generate a significant helicopter noise impact on surrounding residents.

2.5.2          It has been estimated that over 100 village type and medium rise residential buildings, principally in Shan Ting Tsuen, Kam Peng and Tung Wan Villa are presently exposed to noise levels above the 85dB(A) helicopter noise standard under normal operating conditions (i.e., using the quieter EC155 B1 type helicopter).  In particular, the flight path to the existing helipad passes over Sea Crest Villa.

2.5.3          The noise assessment detailed in Section 4 predicts that helicopter noise levels at Sea Crest Villa due to the existing flight path are greater than the 85dB(A) limit. Furthermore, the noise level is predicted to be greater than the corresponding helicopter flight noise level upon operation of the proposed helipad at Pak Wan due to a shorter distance separation.  As such, if the project is not implemented a large number of residents will continue to be adversely affected by helicopter noise, including those at Sea Crest Villa.


3                    Air Quality impact assessment

3.1               Introduction

3.1.1          It should be noted that the EIA Study Brief ESB-091/2001 issued under the Environmental Impact Assessment Ordinance does not include a requirement for an Air Quality Impact Assessment, as use of the proposed helipad will be limited.

3.1.2          This section shall give a brief account of the potential for the construction dust generation and recommendations on the appropriate remedial actions to minimise any potential impacts.  This will be done to ensure compliance with the Air Pollution Control (Construction Dust) Regulation and to ensure effective control of any potential dust impacts.

3.1.3          Emissions from helicopter will be short-lived and occur infrequently during the operation of the helipad due to its emergency nature of use.  No potential operational phase dust impacts are anticipated.

3.2               Relevant Guidelines, Standards & Legislation

Air Pollution Control Ordinance (Cap. 311)

3.2.1          The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of stationary and mobile sources, including fugitive dust emissions from construction sites.  It encompasses Air Quality Objectives (AQOs) for 7 common air pollutants.  The AQOs are given in Table 3.1.

Table 3.1     Hong Kong Air Quality Objectives

 

Concentration (mg/m3)(1)  Averaging Time

Pollutant

1 Hour(2)

8 Hour(3)

24 Hours(3)

3 Months(4)

1 Year(4)

Sulphur Dioxide SO2

800

-

350

-

80

Total Suspended Particulates (TSP)

-

-

260

-

80

Respirable Suspended Particulates (RSP)(5)

-

-

180

-

55

Nitrogen Dioxide NO2

300

-

150

-

80

Carbon Monoxide CO

30000

10000

-

-

-

Photochemical Oxidants (as ozone(6))

240

-

-

-

-

Lead

-

-

-

1.5

-

Notes:

(1) Measured at 298 K and 101.325 kPa (one atmosphere).

(2) Not to be exceeded more than three times per year.

(3) Not to be exceeded more than once per year.

(4) Arithmetic means.

(5) Respirable suspended particulates means suspended particles in air with a nominal aerodynamic diameter of 10 micrometers or less.

(6) Photochemical oxidants are determined by measurement of ozone only.

 

3.2.2          Section 1, Annex 4 of EIA-TM[‡] stipulates the hourly average Total Suspended Particulate (TSP) concentration of 500 mg/m3 measured at 298 K (25°C) and 101.325 kPa (1 atmosphere) for construction dust impacts. Mitigation measures for construction sites specified in the Air Pollution Control (Construction Dust) Regulation should be followed.

3.2.3          The APCO subsidiary regulation Air Pollution Control (Construction Dust) Regulation defines notifiable and regulatory works activities that are subject to construction dust control.

Notifiable Works:

(a)  Site formation;

(b)  Reclamation;

(c)  Demolition of a building;

(d)  Work carried out in any part of a tunnel that is within 100 m of any exit to the open air;

(e)  Construction of the foundation of a building;

(f)  Construction of the superstructure of a building; or

(g)  Road construction work,

Regulatory Works:

(a)  Renovation carried out on the outer surface of the external wall or the upper surface of the roof of a building;

(b)  Road opening or resurfacing work;

(c)  Slope stabilization work; or

(d)  Any work involving any of the following activities:

·         Stockpiling of dusty materials;

·         Loading, unloading or transfer of dusty materials;

·         Transfer of dusty materials using a belt conveyor system;

·         Use of vehicles;

·         Pneumatic or power-driven drilling, cutting and polishing;

·         Debris handling;

·         Excavation or earth moving;

·         Concrete production;

·         Site clearance; or

·         Blasting.

3.2.4          Notifiable works require that advance notice of activities be given to EPD.  The Regulation also requires the works contractor to ensure that both notifiable works and regulatory works will be conducted in accordance with the Schedule of the Regulation, which provides dust control and suppression measures.

3.3               Baseline Conditions and Air Sensitive Receivers

Existing Environment

3.3.1          The existing air quality in Peng Chau is generally rural.  No major air polluting sources are located near Peng Chau.  The nearest potential source is the Penny’s Bay Gas Turbine Plant that is over 3.5km away, due north of Peng Chau.  There are no major road networks within Peng Chau and therefore there are no vehicular emissions related air quality impacts.

3.3.2          Environmental Protection Department (EPD) operates a network of Air Quality Monitoring Stations in Hong Kong, but none of these monitoring stations is located within or near Peng Chau. As such, air quality data collected at the Tap Mun monitoring station in Sai Kung District – which resembles a rural area type setting similar to the environs of Peng Chau – has been selected as being broadly representative of the existing ambient air quality conditions at Peng Chau.  These data are summarised in Table 3.2. [§]

Table 3.2     Annual Average Pollution Concentrations Recorded in Tap Mun (Year 2002)

Pollutants Monitored

Annual Average in micrograms per cubic metre

Respirable Suspended Particulates (RSP)

39

Sulphur Dioxide (SO2)

11

Nitrogen Dioxide (NO2)

13

Carbon Monoxide (CO)

688

Ozone (O3)

63

Notes:     

1.   All concentrations are measured at 298K (25°C) and 101.325KPa (one atmosphere)

2.      Data of the Tap Mun Monitoring Station are extracted from Air Quality in Hong Kong 2002, published by EPD 

 

Future Conditions

3.3.3          Based on current information, the Drainage Services Department’s (DSD) project Peng Chau Sewage Treatment Works (STW) Upgrade at Tai Lei Island will commence in mid 2005.  This STW upgrading work will be a potential fugitive dust source during the works phase.  There may be other construction works to be carried out on the reclaimed area that may be a source of fugitive dust.  However, these will only be a short-term change in the ambient condition locally and will not alter the nature of the air quality condition of Peng Chau once the works are completed. 

3.3.4          Based on the helicopter flight paths advised by GFS, helicopters will not over-fly the Phase 1 Reclamation area and the distance of the sand depot from the helipad would be too far for any dust (wind-blown sand) impacts to be generated.  As such, no adverse air quality (dust) impacts are anticipated from Project operation.  There are no distributor roads or other major infrastructure development planned in Peng Chau and therefore, the air quality conditions are not expected to have any significant change in the future.

Air Sensitive Uses

3.3.5          Sea Crest Villa, a low-rise (3-storey high) residential development, is located at the junction of Peng Lei Road and the future helipad EVA link.  This is the closest domestic air sensitive receiver to the proposed works.  There are no domestic premises in the immediate environs of the helipad site.  Another existing domestic air sensitive use is Kam Peng Estate that is located about 200 metres south east of Sea Crest Villa.  Figure 3.1 displays the locations of Sea Crest Villa and Kam Peng Estate.

3.4               Construction Dust Impact Assessment

Identification of Impacts

3.4.1          If uncontrolled, construction activities dust may result in construction dust impacts.  Construction of the helipad and the associated EVA using reclamation method will include dust generation activities, some of which are notifiable / regulatory works.  They are described below.

3.4.2          The construction will begin with site clearance, including breaking of existing ground near the north of Sea Crest Villa.  This will be a regulatory works procedure that requires appropriate dust suppression measures under the Regulation to adequately control dust to within an acceptable level.

3.4.3          Erection of site office will be required at the off-site works area (approximately 800 m2), which is located immediately south of Sea Crest Villa.  Development of the off-site works area will not involve any dust-generating activities.  However, the erection of hoarding and fencing at the works area may involve very minor excavation that comprises a regulatory works procedure, and for which dust control measures will be implemented.  Dusty material stockpiling and handling will only be conducted in the works area and measures shall be implemented to ensure dust levels are controlled to within an acceptable level.

3.4.4          Reclamation includes dredging and placement of rocks / rubble, is a notifiable work and is controlled by the Regulation.  The dredged materials will have a high moisture content that is unlikely to result in dust emissions.  The fill materials will be directly placed into the water from barge and no fugitive dust impacts are anticipated.

3.4.5          The construction of the helipad and EVA may result in minor wind blown dust impacts.  However, this activity is a regulatory works procedure and requires proper suppression measures to control dust to within an acceptable level.

3.4.6          There may be use of trucks for material transport from the off-site works area to the works area via the existing concrete paved EVA.  Use of vehicles is a regulatory work procedure and the required dust control measures shall ensure dust levels are controlled to an acceptable level.

Cumulative Impacts

3.4.7          Based on the tentative construction schedule of the Drainage Services Department's project Peng Chau Sewage Treatment Works (STW) Upgrade at Tai Lei Island that would commence construction in mid 2005, it would be a cumulative source of dust impacts.  However, dust control measures will be implemented during the helipad construction of which the scale of work is relatively limited.  Furthermore, the DSD’s project also will have to implement dust control measures during their construction phase.   As a result, no significant cumulative dust impacts are anticipated.

Evaluation of Potential Impacts

3.4.8          In view of the small scale of works, construction dust impacts can be controlled with appropriate implementation of dust suppression measures.  Moreover, dust control and suppression measures are statutory requirements under the Air Pollution Control (Construction Dust) Regulation.  As such, fugitive dust impacts during the construction can be adequately controlled and no significant impacts are anticipated.

3.5               Mitigation Measures

3.5.1          All applicable dust control measures as recommended in the Air Pollution Control (Construction Dust) Regulation should be implemented.  Typical dust control measures include:

·        The working area for site clearance adjacent to Sea Crest Villa shall be sprayed with water or a dust suppression chemical immediately before, during and immediately after the operation so as to maintain the entire surface wet.

·        Restricting heights from which materials are dropped, as far as practicable to minimise the fugitive dust arising from unloading/loading.

·        For reclamation works, if a stockpile of dusty materials is more than 1.2 m high and within 50m of Peng Lei Road or the Pak Wan footpath, the stockpile shall be properly treated and sealed with latex, vinyl, bitumen or other suitable surface stabilizer.

·        Immediately before leaving a construction site, every vehicle shall be washed to remove any dusty materials from its body and wheels.

·        All spraying of materials and surfaces should avoid excessive water usage.

·        Where a vehicle leaving a construction site is carrying a load of dusty materials, the load shall be covered entirely by clean impervious sheeting to ensure that the dusty materials do not leak from the vehicle.

·         Travelling speeds should be controlled to reduce traffic induced dust dispersion and re-suspension within the site from the operating haul trucks.

·        Erection of hoarding of not less than 2.4 m high from ground level along the site boundary.

·        Any stockpile of dusty materials shall be either: (a) covered entirely by impervious sheeting; (b) placed in an area sheltered on the top and the 3 sides; or (c) sprayed with water or a dust suppression chemical so as to maintain the entire surface wet.

·        All dusty materials shall be sprayed with water or a dust suppression chemical immediately prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet.

3.6               Environmental Monitoring and Audit Requirements

3.6.1          It is necessary to ensure proper implementation of the dust control measures as required under the Air Pollution Control (Construction Dust) Regulation.  No specific construction dust monitoring is necessary, although environmental audits will be carried out to ensure proper implementation of air quality control measures.

3.7               Conclusions and Recommendations

3.7.1          Through proper implementation of dust control measures as required under the Air Pollution Control (Construction Dust) Regulation, construction dust can be controlled to acceptable level and no significant impacts are anticipated.


4                    Noise impact assessment

4.1               Introduction

4.1.1          This Section provides an evaluation of the potential noise impacts associated with the construction and operational phases of the proposed development of a helipad at Peng Chau.

4.1.2          During the construction phase of the helipad, Powered Mechanical Equipment (PME) used for the helipad construction will be the primary noise sources.  The key noise generating activities include:

·        Site clearance for the erection of site office, hoarding and fencing;

·        Reclamation for the helipad and the Emergency Vehicle Access (EVA); and

·        Construction of helipad and EVA.

4.1.3          The helipad will solely be used for emergency use and associated essential ‘casevac’ training flights, and will not be used for commercial operations.  The sole noise source during the operational phase of the Project will be from helicopter activities, as follows:

·        Helicopter ‘approaching’ the helipad while it is descending at an angle to the helipad surface;

·        Helicopter manoeuvring on and directly over the helipad; and

·        Helicopter ‘taking-off’ from the helipad while it is climbing up at an angle to the helipad surface during departure.

4.1.4          Noise sensitive receivers (NSRs) have been identified in accordance with Annex 13 of the EIA-TM. As required under Clause 3.4.5.2 (iii) (b) of the EIA Study Brief, the selection of representative NSRs has been presented to and agreed by the Authority prior commencement of this noise impact assessment.

4.1.5          Where appropriate, practicable mitigation measures are recommended to alleviate any potential noise impacts identified during both the construction and operational phases of the helipad so that the applicable noise guidelines and regulations can be achieved.

4.2               Relevant Guidelines, Standards & Legislation

Construction Noise During Non-restricted Hours

4.2.1          Noise arising from construction for designated projects during the non-restricted periods, i.e., between 07:00-19:00 hours of any days not being a Sunday or general holiday, is assessed with reference to the noise criteria listed in Table 1B, Annex 5 of the EIA-TM, which are summarized in Table 4.1.  These criteria shall be met as far as practicable according to Annex 5 of the EIA-TM.

Table 4.1     Recommended Construction Noise Levels (Non-restricted Hours)

Noise Sensitive Receiver Uses

Noise Levels Leq(30 min) dB(A)

All domestic premises including temporary housing accommodation, hotels and hostels

75

Schools

70 (normal school hours)

65 (during examination periods)

 

4.2.2          Subsidiary regulations of the Noise Control Ordinance (NCO) include the Noise Control (Hand Held Percussive Breakers) and Noise Control (Air Compressors) Regulations.  These require compliance with relevant noise emission standards and the fixing of noise emission labels to hand-held percussive breakers and air compressor.  Whilst these requirements are not directly relevant to the construction noise impact assessment, contractors must comply with these regulations during the construction phase.

Construction Noise During Restricted Hours

4.2.3          Construction noise is controlled during restricted hours (i.e., between 19:00-07:00 hours and on Sundays and public holidays (anytime for percussive piling) under the NCO and Technical Memoranda (TMs): Noise from Percussive Piling (PP-TM); Noise from Construction Work Other Than Percussive Piling (GW-TM); and Noise from Construction Work in Designated Areas (DA-TM).

4.2.4          A Construction Noise Permit (CNP) is required under the NCO for works involving the use of Power Mechanical Equipment (PME) during restricted hours.  The noise criteria for the use of PME during restricted hours are determined upon the Area Sensitivity Rating (ASR), which ‘ranks’ the background noise conditions of the area in which the NSR is located. Table 4.2 shows the ASR selection criteria as stated in GW-TM.

Table 4.2     Area Sensitivity Rating Criteria

 

Degree to which NSR is affected by IF(4)

Type of area containing the NSR

Not Affected(1)

Indirectly Affected(2)

Directly Affected(3)

(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

Notes:

(1)    Not Affected means that the NSR is at such a location that the noise generated by the influencing factors(4) (IFs) is not noticeable at the NSR.

(2)    Indirectly Affected means that the NSR is at such a location that the noise generated by the IF, whilst noticeable at the NSR, is not a dominant feature of the noise climate of the NSR.

(3)    Directly Affected means that the NSR is in such a location that the noise generated by the IF is readily noticeable at the NSR and is a dominant feature of the noise climate of the NSR.

(4)      IFs are defined as industrial areas, major roads or the area within the boundary of Hong Kong International Airport.

 

4.2.5          The noise criteria for construction noise during restricted hours for each ASR are given in Table 4.3.

Table 4.3     Acceptable Noise Levels in Leq(5 min) dB(A)

Time Period

Area Sensitivity Rating

 

A

B

C

All days during the evening (1900-2300) and general holidays (including Sundays) during the day and evening (0700-2300)

60

65

70

All days during the night-time (2300-0700)

45

50

55

 

4.2.6          Regardless of any description or assessment made in the following paragraphs, in assessing a filed application for a CNP the Noise Control Authority will be guided by the relevant Technical Memoranda. The Authority will consider all the factors affecting their decision taking contemporary situations / conditions into account.  Nothing in this Report shall bind the Authority in making their decision, and there is no guarantee that a CNP will be issued.  If a CNP is to be issued, the Authority shall include any conditions they consider appropriate, and such conditions are to be followed while the works covered by the CNP are being carried out.  Failing to do so may lead to cancellation of the permit and prosecution action under the NCO.

4.2.7          There are some factors affecting the assessment results of a CNP application, such as the assigning of Area Sensitivity Rating, Acceptable Noise Levels etc.  The Noise Control Authority would decide these at the time of assessment of such an application based on the contemporary situations/conditions. It should be noted that the situations/conditions around the sites may change from time to time.

Helicopter Noise

4.2.8          Table 1A, Annex 5 of the EIA-TM stipulates the noise standards of the helicopter noise (between 07:00 and 19:00 hours) for planning purposes.  These are summarized in Table 4.4.

Table 4.4     Helicopter Noise Standards for Planning Purposes

Uses

Helicopter Noise Lmax dB(A)
07:00 to 19:00 hours

-    All domestic premises including temporary housing accommodation;

-    Hotels and hostels

-    Educational institutions including kindergartens, nurseries and all others where unaided voice communication is required

-    Place of public worship and courts of law

-    Hospitals, clinics, convalescences and home for the aged, diagnostic rooms, wards

 

85

Offices

90

Notes:

(1)    The above standards apply to uses that rely on opened windows for ventilation.

(2)    The above standards shall be viewed as the maximum permissible noise levels assessed at 1 m from the external façade.

 

4.2.9          There are no specified night-time helicopter noise guidelines for the HKSAR, and accordingly a document review was undertaken to determine international practice. The review included the US Federal Aviation Agency (US FAA), the International Civil Aviation Organization, the US-based National Organization to Insure a Sound-controlled Environment (NOISE), and various individual airport / heliport web-sites.

4.2.10      From this review it was identified that most literature on aircraft noise concerns relates to commercial airplane and helicopter noise.  However, during the ‘US FAA [public] Hearings on [non-military] Helicopter Noise’ it was noted that noise from emergency medical services was to be exempted in the list of “Recommended Noise Reduction Approaches”.[**]  In other words, after widespread consultation the public expressed their general tolerance of noise from emergency helicopter operations.  This situation also applies to existing casevac operations for Peng Chau, which both GFS and CAD confirm have never received a noise complaint from the local community.

4.2.11      Recognising the tolerable necessity of emergency helicopter flights at night-time, during the US FAA hearings it was remarked that consideration might be given to imposing some regulation on these operations to reduce noise impacts to NSRs.  Such consideration has been given during the course of this EIA Study in determining both the proposed helipad location and the proposed helicopter flight-path, and such details are provided in Section 4.6.


4.3               Noise Sensitive Receivers

4.3.1          Noise sensitive receivers (NSRs) have been identified in accordance with the criteria set out in Annex 13 of the EIA-TM.  The spatial scope of the noise impact assessment shall include all areas within 300 metres from the Project boundary in accordance with the EIA Study Brief.

4.3.2          Site visits have been conducted to ensure the selection of representative existing NSRs. A review of the latest Outline Zoning Plan (Peng Chau OZP No. S/I-PC/6), Outline Development Plan (Peng Chau ODP No. D/I-PC/2), and consultation with the Planning Department was conducted to identify the most likely location for future / potential future NSRs. 

4.3.3          As required under Clause 3.4.5.2 (iii) (b) of the EIA Study Brief, the selection of representative NSRs has been presented to and agreed by the Authority prior to commencement of this noise impact assessment.  A brief description of existing and planned NSRs is provided below, while Figure 4.1 displays their locations.

Existing Noise Sensitive Receivers

4.3.4          Peng Chau has been developed mainly with low-rise developments that are located in the central portion of the island.  At the northwest of Peng Chau close to the proposed helipad site, there are low-rise (3 storeys) apartment type residential buildings and a medium-rise (7 storeys) public housing estate that are NSRs.  Given the natural hilly topography at northwest Peng Chau there is no direct line of sight between the NSRs and the proposed helipad (i.e., there is natural shielding of noise at NSRs).

4.3.5          Based on site visits, Blocks C and D of Sea Crest Villa (NSR1 and NSR2) are located approximately 160 metres west-southwest of the proposed helipad and are the closest NSRs to the proposed helipad.  These two NSRs have a direct line of sight to part of the EVA works area.  Kam Peng House at Kam Peng Estate (NSR3) is located further south (about 330m) of the proposed helipad and the line of sight is completely blocked by the northern ridgeline at Peng Chau.  These existing NSRs have been selected as representative NSRs for the noise impact assessment.

4.3.6          Block A of Sea Crest Villa (NSR7) does not have a direct line of sight to the helipad, but is included to assess the impact of the off-site works area for the project that is located on reclaimed land approximately 15 metres to the south.[††]  The noise impact for this NSR has been assessed for the construction phase only.

Planned Noise Sensitive Receivers

4.3.7          The main purpose of selecting planned NSRs is for the assessment of future noise impacts due to the operation of the helipad.  Based on the current Peng Chau OZP No. S/I-PC/6 and the latest Peng Chau ODP No. D/I-PC/2, three potential future NSRs have been selected and agreed by the Authority.

4.3.8          One potential future NSR, denoted by NSR4, is located within a “Government, Institution or Community” zone to the southeast of the helipad site. It is designated for educational use and has been assumed to be a school with a maximum building height of 24 metres.  Another NSR is located within a “Residential (Group B)” zone (assuming maximum 8-storey, 24 metres high), namely NSR5, and the third NSR is located within an “Other Specified Uses” zone annotated “Comprehensive Residential Development including a Commercial Complex”, namely NSR6, which is subjected to a maximum building height of 2 storeys not exceeding 6m and 8m for residential blocks and commercial complex, respectively.

4.3.9          The characteristics of NSRs in the vicinity of the proposed Peng Chau Helipad are summarised in Table 4.5.  Figure 4.1 illustrates their locations. Figures 4.5a and 4.5b display cross sections for NSRs 1-6.

Table 4.5     Location of NSR Assessment Points in Peng Chau

NSR Assessment Point

NSR Location

Number of storeys

Ground Level (mPD)

Land Use

NSR1

Sea Crest Villa - Block D, Flat A

3

4.8

Residential

NSR2

Sea Crest Villa - Block C, Flat A

3

4.8

Residential

NSR3

Kam Peng Estate – Kam Peng House

7

4.7

Residential

NSR4*

Future Development in “Government, Institution or Community” Zone

24 metres#

20.0

School

NSR5*

Future Development in “Residential (Group B)” Zone

8 storey (maximum 24 metres)#

6.0

Residential

NSR6*

Future Development in “Other Specified Uses” Zone

2 storey (residential: 6 m; commercial: 8 m)#

3.9

Commercial & Residential

NSR7^

Sea Crest Villa - Block A, Flat B

3

4.8

Residential

Notes:

*     Location of NSRs is based upon the most updated Peng Chau OZP No.S/I-PC/6 and ODP No. D/I-PC/2.

#     Maximum building height based upon the most updated Peng Chau OZP No.S/I-PC/6 (gazetted on 15.4.2005).

^     Existing NSR used for construction noise impact assessment only.

 

4.4               Noise Environment at Peng Chau

Existing Noise Environment at NSRs

4.4.1          Peng Chau is an outlying island with limited road network, and has no major road traffic related noise sources.  However, it is observed from site visits that there are motorized carts travelling within Peng Chau, e.g., route to Tai Lei Island, which may generate potential noise impacts affecting the residences living along the routes such as Sea Crest Villa.  The noise environment at Peng Chau is dominated by human activities, with most activities during daytime hours.

4.4.2          CEDD is monitoring noise levels at north Peng Chau (Sea Crest Villa) due to construction works at Penny’s Bay.[‡‡]  The noise monitoring results for the three months June - August 2003 are summarised in Table 4.6 to demonstrate baseline noise levels at north Peng Chau.  There has been no development in the area since this time that would have lead to a change in the baseline noise environment.

Table 4.6     Noise Monitoring Results at Sea Crest Villa

Time Period

June 2003

July 2003

August 2003

Day Time Leq(30 min)

54 – 66 dB(A)

51 – 64 dB(A)

55 – 62 dB(A)

Evening Time Leq(15 min)

49 – 57 dB(A)

52 – 57 dB(A)

45 – 52 dB(A)

Night Time Leq(15 min)

45 – 54 dB(A)

48 – 61 dB(A)

50 – 56 dB(A)

Source: Webpage http://www.pennysbaycontract1.com/noise1.html

 

Future Trend

4.4.3          Based on the latest planning information, the Peng Chau Sewage Treatment Works (STW) upgrading works are a potential noise source that may affect NSRs close to the works site during construction. There will be no significant change in the noise environment at Peng Chau upon completion of the upgrading works.  Future increase in the population (upon occupancy of all planned developments) may result in more human activity and potentially a higher noise background.

4.5               Construction Noise Impact Assessment

Assessment Methodology

4.5.1          This construction noise impact assessment has been conducted based on the construction schedule and equipment inventory as presented in Appendix 2.2 and Appendix 4.1, respectively.  The construction schedule provided by CEDD is based upon all works to be undertaken during non-restricted hours only. The construction noise impacts at representative NSRs were assessed using the methodology specified in Annex 13 of the EIA-TM.  The noise level at the most affected floor (i.e., 1/F) has been assessed and appropriate corrections such as façade correction and barrier correction have been applied.

4.5.2          Based on the construction schedule, the noise assessment has been divided into 27 ‘assessment periods’ throughout a 12-month construction period in accordance with the worst-case sound power level that may arise from the Site.  Each ‘assessment period’ represents a distinct construction task in the overall programme that can be used as a basis for construction noise impact assessment.

Identification of Potential Construction Noise Impacts

4.5.3          It is anticipated that the use of Powered Mechanical Equipment (PME) during the construction phase will generate potential noise impact upon the existing NSRs in the vicinity of the helipad site.  Based on a practicable equipment inventory provided by the Project Proponent, Table 4.7 presents the likely PME that shall be used to construct the Project according to schedule and the corresponding sound power levels.

Table 4.7     Powered Mechanical Equipment to be used for Construction of Helipad

Identification Code

Description

Sound Power Level, dB(A)

CNP 003

Air compressor

104

CNP 021

Bar bender (electric)

90

CNP 045

Concrete mixer (electric)

96

CNP 048

Crane, mobile (diesel)

112

CNP 061

Derrick barge/ Split barge

104

CNP 063

Dredger, grab

112

CNP 067

Dump truck

117

CNP 081

Excavator/ Backhoe

112

CNP 101

Generator, Standard

108

CNP 170

Poker, vibratory, hand-held

113

CNP 186

Roller, vibratory

108

CNP 221

Tug boat

110

Source: GW-TM.

 

4.5.4          The entire construction sequence can be separated into four activities according to the construction schedule given in Appendix 2.2 and as summarised in Table 4.8.  The geographical centre for each activity to determination the equipment locations (i.e., Notional Source Position[§§]) for the calculation of construction noise levels are presented in Figure 4.2.


Table 4.8     Construction Activities

Construction Activities

Details of Works

Site Clearance

·       Existing ground breaking;

·       Removal of demolition/ waste materials; and

·       Erection of office, hoarding and fencing

Reclamation

·       Dredging;

·       Placing/ trimming of pell mell rubble;

·       Placing/ trimming of rock underlayer; and

·       Placing/ trimming of rock armour.

Construction of Helipad

·       Casting pre-cast concrete wave deflector;

·       Installation of pre-cast wave deflector;

·       Filling the pad with granular material;

·       Compaction of foundation material;

·       Construct reinforced concrete slab; and

·       Install helipad facilities.

Construction of EVA

·       Filling EVA with granular material;

·       Compaction of foundation material;

·       Construct reinforced concrete slab;

·       Associated drainage;

·       Install railing and other E&M facilities; and

·       Landscape work.

Prediction and Evaluation of Construction Noise Impacts

4.5.5          Based on the construction schedule and equipment inventory, the predicted unmitigated construction noise levels for each assessment period is summarised in Table 4.9.  Detailed calculations are presented in Appendix 4.2.

Table 4.9     Predicted Construction Noise Levels Leq(30 min) dB(A) - Unmitigated

Assessment Period #

NSR1

NSR2

NSR3

NSR4

NSR5

NSR6

NSR7

1

78*

80*

64

56

68

83*

80*

2

84*

85*

64

59

68

84*

80*

3

60

61

64

53

67

83*

80*

4

56

56

49

56

54

53

54

5

77*

77*

54

58

58

67

62

6

82*

82*

57

61

62

72

66

7

80*

80*

55

60

60

70

64

8

81*

81*

56

60

61

71

65

9

74

74

52

57

57

64

59

10

77*

77*

53

58

58

67

61

11

76*

77*

51

55

56

67

61

12

77*

77*

52

57

57

67

61

13

74

74

51

56

55

64

59

14

80*

81*

53

57

57

67

62

15

77*

77*

51

56

56

65

60

16

77*

77*

51

56

56

65

60

17

83*

84*

55

59

60

70

65

18

83*

84*

54

58

59

70

65

19

83*

84*

56

61

61

70

65

20

83*

84*

55

60

60

69

65

21

84*

85*

56

61

61

71

66

22

85*

86*

56

61

61

71

66

23

85*

86*

57

61

61

71

67

24

80*

82*

54

60

59

67

63

25

74

75

53

59

57

62

59

26

74

75

46

51

51

61

56

27

79*

80*

50

54

55

66

61

Notes:#    * ‘Assessment Period’ refers to distinct construction tasks in the works programme [Appendix 4.2 refers].

* Predicted noise level exceeds the 75 dB(A) noise standard.

4.5.6          Due to the proximity of the site, the highest unmitigated construction noise levels at NSR1, NSR2, NSR6 and NSR7 (i.e. Sea Crest Villa and the planned development on the reclaimed land) are predicted to be more than 80 dB(A).  As such, appropriate mitigation measures are required in order to reduce construction noise to an acceptable level.  Given the distance separation and topography between NSR3, NSR4 and NSR5 (i.e. Kam Peng Estate, a planned school and a planned residential development) and the site, the predicted noise levels at these NSRs are within the noise standard.

Mitigation of Adverse Construction Noise Impacts

4.5.7          Given the mobile nature of the equipment (e.g. dump truck and backhoe), the use of silenced equipment is an effective option to alleviate the noise impacts.  The maximum sound power levels for the proposed silenced equipment are presented in Table 4.10.

Table 4.10   Sound Power Levels for the Silenced Equipment

Identification Code

Description

Sound Power Level, dB(A)

Source of Information

CNP 001

Air compressor

100

NCO GW-TM, CNP 001

CNP 067

Dump truck

109

BS5228, Table C.3 Item 52

CNP 081

Excavator/ Backhoe

102

BS5228, Table C.8 Item 33

CNP 103

Generator, super silenced, 70 dB(A) at 7m

95

NCO GW-TM, CNP 103

CNP 170

Poker, vibratory, hand-held

100

BS5228, Table C.6 Item 32

 

4.5.8          Apart from the use of silenced equipment, other practicable mitigation measures were considered. However, given the small site area, only the erection of temporary movable noise barriers was identified as a possible solution to further mitigate the noise impacts.  It is recommended the movable noise barriers should be positioned as close as possible to PMEs such that none of the PMEs will be visible when view from any noise sensitive façades.

4.5.9          The predicted construction noise levels with the implementation of the silenced equipment and the erection of noise barriers are summarised in Table 4.11.  Detailed calculations are presented in Appendix 4.3.

Table 4.11   Predicted Construction Noise Levels Leq(30 min) dB(A) – Mitigated

Assessment Period

NSR1

NSR2

NSR3

NSR4

NSR5

NSR6

NSR7

1

65

66

54

46

57

73

69

2

70

72

54

50

58

73

69

3

50

51

53

43

57

73

69

4

45

46

39

46

44

42

44

5

72

72

52

55

56

67

61

6

75

75

54

58

59

70

64

7

71

71

51

55

55

66

60

8

72

72

51

55

56

67

61

9

62

62

43

48

48

57

52

10

65

65

46

50

50

60

54

11

65

65

44

48

49

60

54

12

65

66

49

55

54

60

56

13

63

63

48

54

53

58

54

14

68

69

49

55

54

61

57

15

70

71

50

55

54

62

58

16

69

71

47

51

52

62

57

17

68

69

46

51

51

61

56

18

68

69

47

52

52

61

56

19

68

69

46

50

50

61

55

20

66

68

44

48

48

58

53

21

68

70

45

49

50

60

55

22

69

70

45

50

50

61

56

23

69

70

45

50

50

61

56

24

65

67

43

48

48

57

53

25

59

61

41

47

46

51

48

26

59

60

36

40

40

51

46

27

64

65

40

43

45

56

51

 

4.5.10      Table 4.11 illustrates that with the application of mitigation, the construction noise levels may be reduced to within acceptable limits. As such, there are no residual impacts.  Nevertheless, it is recommended that the Contractor should also adopt good working practices in order to minimise construction noise as far as possible:

·        Noisy equipment and noisy activities should be located as far away from the NSRs as is practical;

·        Unused equipment should be turned off;

·        Powered mechanical equipment should be kept to minimum and the parallel use of noisy equipment / machinery should be avoided;

·        Regular maintenance of all plant and equipment; and

·        The Contractor shall observe and comply with the statutory requirements and guidelines.

Cumulative Noise Impacts

4.5.11      Based on the information obtained from the Drainage Services Department, works for the STW upgrading project at Tai Lei Island are tentatively scheduled to commence in mid-2005.  The works programme is presented in Appendix 2.3.

4.5.12      According to the construction schedule of the helipad site, the 12-month works will commence in December 2005.  Therefore, both sites will be constructed in parallel throughout the entire construction period of the helipad.  Given the proximity of two sites, there is potential for cumulative construction noise impacts upon common NSRs.

4.5.13      It has been identified that NSR1 (Block D, Flat A of Sea Crest Villa) will be the closest and therefore the most affected NSR for both sites, and was therefore selected for cumulative noise impact assessment.  Based on the DSD’s EIA Study for the STW upgrade project, the unmitigated cumulative construction noise impacts at NSR1 during the 12-month construction period of the helipad will exceed the noise standard of 75 dB(A).  Accordingly, mitigation measures should be implemented for both projects to reduce their individual noise contribution down to 72 dB(A) or below at the common NSR1.

4.5.14      The construction equipment to be used during Assessment Period 6 (i.e., reclamation works from 20 February 2006 to 7 March 2006) are tugboats, derrick barges, split barges and a grab dredger for which no silenced type models are available.  Moreover, as these PME are to be operated on the sea, mitigation options are limited.  However, erecting a 3m high mobile barrier along the coastline north of Peng Lei Road can mitigate construction noise.  As the reclamation works progress along the coastline to the east, the distance separation between PMEs and NSR1 will increase and hence noise levels will decrease until PME are screened from sight by the hilly terrain immediately northeast of Sea Crest Villa.

4.5.15      According to Appendix 4.4, it has been identified that NSR1 will be exposed to a construction noise level of 74.5 dB(A) during ‘Period 6’.  As such, it is anticipated that the cumulative noise level may exceed the 75 dB(A) standard if the noise contribution from the STW Upgrade project exceeds 68 dB(A).  However, in consultation with DSD it has been determined that the noise contribution from the STW Upgrade project during ‘Period 6’ is 67.4 dB(A).[***]  As such, the cumulative noise impact is predicted to be below 75 dB(A) at all NSRs, and accordingly no residual impacts are anticipated.  The predicted cumulative construction noise levels at the common NSR1 are summarised in Table 4.12 and detailed calculations are presented in Appendix 4.4.

Table 4.12   Predicted Cumulative Construction Noise Levels Leq(30 min) dB(A) at NSR1

Assessment Period

Predicted Noise Level (Leq(30 min)) dB(A)

Assessment Period

Predicted Noise Level (Leq(30 min)) dB(A)

Assessment Period

Predicted Noise Level (Leq(30 min)) dB(A)

1

70

10

71

19

72

2

72

11

71

20

71

3

68

12

71

21

72

4

68

13

70

22

72

5

73

14

72

23

72

6

75

15

73

24

70

7

73

16

73

25

69

8

74

17

72

26

69

9

70

18

72

27

70

4.6               Operational Noise Impact Assessment

Assessment Methodology

4.6.1          Noise associated with the proposed helipad at Peng Chau will be generated during helicopter manoeuvring over the helipad and during lateral (approach / departure) flight. The different operational modes that may generate noise are summarised as follows:

Without Lateral Movements

Helicopter manoeuvring above the helipad within the Final Approach and Take-off Areas (FATO)[†††] includes several modes:

·        ‘Hovering’ – helicopter turns on the spot over the helipad to achieve the desirable orientation for touchdown / lift-off;

·        ‘Touchdown’ – helicopter descends on to the helipad surface;

·        ‘Idling’ – helicopter remains on the helipad surface with its rotary blades kept running; and

·        ‘Lift-off’ – helicopter ascends vertically from the helipad surface to achieve a hover before departure.

With Lateral Movements

·        Helicopter ‘approaching’ the helipad while it is descending at an angle to the helipad surface; and

·        Helicopter ‘taking-off’ from the helipad while it is climbing up at an angle to the helipad surface.

4.6.2          According to Table 1A, Annex 5 of the EIA-TM, helicopter noise impacts shall be assessed in terms of the Lmax level, which is the maximum instantaneous sound pressure level at the noise sensitive receiver. Since all the identified NSRs are located at considerable distances (over 150 m) from the helipad, helicopter noise can be considered as a ‘point’ source.  Therefore, the sound pressure level at NSRs can be evaluated based on standard acoustic principle of a ‘point’ source, i.e., the sound pressure level in any direction (in the open) will decrease at a rate of 6 dB per doubling of distance away from the source.  The difference in noise levels at two different distances, r1 and r2, can be calculated using the following formula:

Noise Level Difference (dB) = 20 log10

4.6.3          Noise source terms (i.e., the Lmax at a given distance) for each helicopter operation mode have been provided by the Government Flying Service (GFS).  On site noise measurements have also been conducted to supplement the noise source terms data.

4.6.4          The International Civil Aviation Organization (ICAO) has stipulated noise standard for helicopters for different flying modes, including ‘approach’, ‘take-off’ and ‘flyover’ (i.e., the maximum noise level [in EPNdB] used as the noise certification standards adopted by the Council of ICAO).  The noise standards for the two types of GFS’ helicopter used for ‘casevac’ operations are summarized in Table 4.13, with test noise measurement points for each flying mode illustrated in Appendix 4.5.  Table 4.13 also presents the Demonstrated Noise Level data for the GFS helicopters as tested by the helicopter manufacturer (i.e., the noise level for that helicopter type measured by the manufacturer in accordance with standard technical procedures in the ICAO noise certification).

Table 4.13   Helicopter Noise Data – Airborne Helicopter with Lateral Movements

Reference Measurement Configurations

Super Puma AS332 L2

EC155 B1

ICAO Max. Noise Level EPNdB

Demonstrated Noise Level EPNdB

ICAO Max. Noise Level EPNdB

Demonstrated Noise Level EPNdB

Approach

100.7 (87.7)

96.1 (83.1)

97.9 (84.9)

95.7 (82.7)

Take-off

99.7 (86.7)

94.6 (81.6)

96.9 (83.9)

92.2 (79.2)

Flyover

98.7 (85.7)

93.5 (80.5)

95.9 (82.9)

88.9 (75.9)

Notes:

Figures in brackets are the Lmax dB(A) values.

Lmax = EPNdB – 13, with reference to the ‘Transportation Noise Reference Book’ (Nelson, 1987).

 

4.6.5          Based on the given noise data in Table 4.13, the ‘approach’ mode generates the highest noise level when the helicopter is airborne with lateral movements.  Accordingly, the helicopter noise assessment makes reference to the ICAO standard for the approach mode that represents the worst-case scenario. By assessing the worst-case scenario any uncertainty in the quantitative prediction has been taken into consideration.

4.6.6          According to GFS Helipad Specification Guidelines, the helicopter approach and departure trajectory will be projected at an 8% slope within 245 metres from the edge of the helipad.  Beyond 245 metres the slope increases to 12.5%.  GFS has advised that the approach and departure angle is generally within the sector between the bearings of 300 and 055 degrees from the centre of the helipad [Figure 4.3 refers].  Accordingly, the closest distance between the airborne helicopter and the identified NSR (on the top floor) can be measured and used for evaluating the worst-case noise level. 

4.6.7          The ICAO standards do not include standards for helicopter manoeuvring on and over the helipad, i.e., hovering, touchdown, idling and lift-off.  As such, on-site noise surveys on GFS’s helicopters were conducted at GFS helipad at Chek Lap Kok on 24 June 2003 to generate supplementary noise data. The noise survey involved measuring the Lmax noise level generated by GFS helicopters simulating manoeuvring on and over a helipad.  The measurements were taken at the far-field region such that the formula quoted below paragraph 4.6.2 can be applied.  The Lmax noise level measured has been used for assessing the worst-case scenario when the helicopter is at the helipad.  Details of the noise survey are provided in Appendix 4.6.

4.6.1          It was found that the Lmax noise level is less when helicopter is idling (with rotors on) on ground and the Lmax noise level occurs when the helicopter is in the air without lateral movements (either during lift-off mode or hovering mode).  Table 4.14 displays the measured Lmax noise levels.

Table 4.14   Measured Lmax Noise Level of GFS Helicopters – Without Lateral Movements

Measurement Configurations  (Reference distance: 150m)

Super Puma AS332 L2

EC155 B1

Helicopter on ground, Idling

82.0

80.0

Helicopter in the air *

90.6

87.7

Notes:

Lmax noise levels in dB(A).

* For ‘Super Puma AS332 L2’, the Lmax noise level is measured during the hovering mode.

   For ‘EC155 B1’, the Lmax noise level is measured during the lift-off mode.

Identification of Potential Noise Impacts

4.6.2          Assessment of helicopter noise has been conducted for each of the operational modes as introduced in paragraph 4.6.1.

4.6.3          The GFS will use the proposed helipad for ‘casevac’ operations.  GFS’ helicopter fleet comprises two helicopter types: the Super Puma AS332 L2 and EC155 B1.  The Super Puma has a higher maximum operational weight than the EC155 B1, and hence operates at a higher power output and generates a higher noise level.  However, GFS has agreed to deploy the ‘EC155 B1’ type helicopter whenever possible for ‘casevac’ operations, and only under very special circumstances shall the Super Puma be deployed.

4.6.4          The Super Puma was introduced into the GFS helicopter fleet in November 2001, while the EC155 B1 was introduced into the GFS fleet in November 2002.  Prior to this time the GFS relied on Sikorsky S76 / Sikorsky S70 type helicopters for casevac operations, and these were phased out during 2003. Table 4.15 summarises actual GFS helicopter usage data for ‘casevac’ operations from 2000 through 2004.

Table 4.15   Helicopter Use for Peng Chau ‘Casevac’ Operations during years 2000 – 2004

Year

Total No. of Casevac from  0700 to 2200 hours1

Total No. of Casevac from 2200 – 0700 hours2

No. of Casevac Training Flights3

2000

97 (1)

51

2

2001

125 (9)

57

3

2002

234 (29)

56

5

2003

167 (4)

42

5

2004

140 (5)

37

3

Notes:

1.        The figures in brackets ( ) are the number of casevac flights carried out by Super Puma (or Sikorsky prior to 2004).

2.        Since 2003, all nighttime casevac has been undertaken using the EC155 B1 type helicopter only, although for the purpose of this noise impact assessment it cannot be discounted that the Super Puma may be required for nighttime casevac in future years.

3.        Five casevac training flights were conducted to the Peng Chau helipad in 2003 (i.e., an additional 2.3% of the total casevac flights).  As no such data is available for other years, the number of casevac training flights for 2000-2002 and 2004 have been calculated using the same % contribution.  It should be noted that GFS does not anticipate any increase in training flights in the short to medium term as the helicopter fleet was upgraded in 2001/02 and there are no plans to add additional types of helicopters.’

 

4.6.5          Using the flight data for the year 2002 as a worst-case scenario, it has been assumed that there may be a total of 295 flights in a single year.  Of this total it has been assumed that the ‘Super Puma’ would be operated for up to 29 casevac flights a year.  In the absence of a specific data breakdown, it has also been assumed that two of the five training flights would be using the Super Puma.  Overall, as a worst-case scenario it is assumed that the Super Puma would be used on no more than 31 ocassions in a year: equivalent to one flight every 12 days.

4.6.6          Using the same calculation method, and including all nigh-time flights, it has been assumed that the EC155 B1 type helicopter would be used for casevac at Peng Chau on no more than 264 ocassions in a year: equivalent to one flight every 1.4 days.

Cumulative Helicopter Noise Impacts

4.6.7          Upon commencement of operations at the proposed Peng Chau helipad, use of the currently used landing site on the soccer pitch near Tai Lung Tsuen will cease.  There are no other helipads located in the vicinity of the proposed helipad that would cause any cumulative helicopter noise impacts.  GFS also confirmed that only one helicopter will use the helipad at one time and therefore no cumulative noise impacts are anticipated.

4.6.8          There is no other significant noise source in the area that may contribute to a cumulative operational noise effect.

Prediction and Evaluation of Noise Impacts

Without Lateral Movements

4.6.9          The assessment of helicopter noise generated at the helipad is based on the Lmax noise levels of the helicopter manoeuvring over the helipad and the horizontal separation between the helipad and identified NSRs.  Table 4.16 summarises the calculated Lmax noise levels at the identified NSRs.  Details of the calculation, including terrain cross-sections relevant for noise level calculations for the NSRs are provided in Appendix 4.7.

Table 4.16   Worst-case Helicopter Noise Levels at NSRs during Helicopter Manoeuvring

NSR ID

Horizontal separation to centre of the Helipad (metres)

Lmax @ NSR dB(A) 1

Façade Correction dB(A)

Topographical Correction dB(A) 2

Corrected Lmax @ NSR dB(A)

Super Puma AS332 L2

EC155 B1

Super Puma AS332 L2

EC155 B1

NSR1

167

90 (81)

87 (79)

3

-10

83 (74)

80 (72)

NSR2

156

90 (82)

87 (80)

3

-10

83 (75)

80 (73)

NSR3

336

84 (75)

81 (73)

3

-10

77 (68)

74 (66)

NSR4*

162

90 (81)

87 (79)

3

-10

83 (74)

80 (72)

NSR5*

193

88 (80)

86 (78)

3

-10

81 (73)

79 (71)

NSR6*

238

87 (78)

84 (76)

3

-10

80 (71)

77 (69)

Notes:

1 Calculated with reference to measured Lmax noise level at reference distance of 150m.

2 By standard acoustic principles, if the noise source is totally screened such that none will be visible when viewed from any façade of the NSR, a negative topography correction of 10 dB(A) shall be applied.

*  Future NSR.

Figures in brackets are the Lmax during the idling mode.

 

4.6.10      The evaluation results in Table 4.16 show that the worst-case Lmax noise level during helicopter manoeuvre above the helipad without lateral movements complies with the 85 dB(A) limit for both helicopter types.

With Lateral Movements

4.6.11      Regarding the helicopter approach mode, the projected worst-case trajectory of the approach path (i.e., closest to the NSR), is at the bearing of 300 degrees to the centre of the proposed helipad.  NSR1, NSR2, NSR4 and NSR5 are closest to the approach path and will therefore be the most affected by helicopter noise during approach. While NSR1 and NSR2 are exposed to helicopter flight noise, shielding by the natural terrain reduces the predicted noise level at NSR 4 and NSR5 to an acceptable level.  Cross-sections showing the influence of topography on NSRs 3-4 and NSRs 5-6 are displayed by Figure 4.5c and Figure 4.5d, respectively. Figure 4.4b presents a plan of the cross-sections.  Table 4.17 displays the worst-case Lmax noise levels, based on the ICAO maximum noise level. Calculation details are provided in Appendix 4.7.

Table 4.17   Worst-case Helicopter Approach / Departure Noise Levels at NSRs

NSR ID

Slant distance between helicopter & NSR (m)

Lmax @ NSR dB(A) 1

Façade Correction dB(A)

Topographical Correction dB(A) 2

Corrected Lmax @ NSR dB(A)

Super Puma

EC155 B1

Super Puma

EC155 B1

NSR1

163

85

82

3

0

88

85

NSR2

161

85

82

3

0

88

85

NSR3

336

79

76

3

-10

72

69

NSR4

165

85

82

3

-10

78

75

NSR5

193

84

81

3

-10

77