New World First Bus Services Limited

 

 

 

 

 

 

 

 

 

 

 

Environmental Impact Assessment

New World First Bus Permanent Depot

at Chai Wan

Volume 1

 

Environmental Impact Assessment Report

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Prepared by:

Westwood Hong & Associates Ltd

Supported by

ERM-Hong Kong Ltd

 

 

 

DECEMBER 1999

TABLE OF CONTENTS

1. INTRODUCTION *

1.1 Background of the Project *

2. project description *

2.1 Site Selection *

2.2 Site Location and Site History *

2.3 Design of the Depot *

3. Scope of the assessment *

3.1 Purpose of the Study *

3.2 Broad Study Objectives *

3.3 Structure of the Report *

3.4 Project Implementation Programme *

4. air quality *

4.1 Introduction *

4.2 Legislation and Standards *

4.3 Baseline Conditions *

4.4 Representative Air Sensitive Receivers (ASRs) *

4.5 Dust Dispersion Assessment *

4.6 Depot Emission Assessment *

4.7 Road Traffic Vehicular Emission Assessment *

4.8 Cumulative Impacts *

4.9 Mitigation Measures *

4.10 Environmental Monitoring & Audit (EM&A) Requirements *

4.11 Summary and Conclusions *

5. Noise *

5.1 Introduction *

5.2 Legislation and Standards *

5.3 Baseline Conditions *

5.4 Representative Noise Sensitive Receivers *

5.5 Construction Noise Assessment *

5.6 Operational Noise Sources *

5.7 Depot Operational Noise Assessment *

5.8 On-Site Vehicular Noise Assessment *

5.9 Off-Site Traffic Noise Assessment *

5.10 Mitigation Measures *

5.11 Environmental Monitoring & Audit (EM&A) Requirements *

5.12 Summary and Conclusions *

6. waste management *

6.1 Introduction *

6.2 Legislation and Standards *

6.3 Construction Waste *

6.4 Evaluation of Construction Waste Impacts *

6.5 Operational Waste *

6.6 Evaluation of Operation Waste Impacts *

6.7 Waste Management Plan *

6.8 Environmental Monitoring & Audit (EM&A) Requirements *

6.9 Summary and Conclusions *

7. land contamination *

7.1 Introduction *

7.2 Legislation and Standards *

7.3 Baseline Conditions *

7.4 Potential Sources of Land Contamination *

7.5 Contamination Avoidance Plan *

7.6 Environmental Monitoring & Audit (EM&A) Requirements *

7.7 Summary and Conclusions *

8. Hazard ASSESSMENT *

8.1 Introduction *

8.2 Proposed New World First Bus Permanent Depot *

8.3 CRC Chai Wan Oil Terminal *

8.4 Hazard Identification *

8.5 Consequence Modelling *

8.6 Risk Assessment *

8.7 Base Case Results *

8.8 Analysis of Mitigation Measures *

8.9 Conclusions *

8.10 Recommendations *

8.11 References *

9. Summary of Environmental outcome *

9.1 Introduction *

9.2 Environmental Benefits *

10. overall conclusion and recommendation *

10.1 Introduction *

10.2 Air Quality Assessment *

10.3 Noise Assessment *

10.4 Waste Management Impact Assessment *

10.5 Land Contamination Assessment *

10.6 Hazard Assessment *

10.7 Recommendations *

10.8 EM&A Requirements *

10.9 EMS Requirements *

 

LIST OF TABLES

Table 2.3.1 Maximum No. of persons present within the proposed depot building *

Table 2.3.2 Facility Provisions of the proposed depot *

Table 4.2.1 Hong Kong Air Quality Objectives *

Table 4.4.1 Representative ASRs closest to the project site *

Table 4.5.1 Predicted Maximum 1-hour and 24-hour TSP concentrations at ground floor level *

Table 4.6.1 Bus Flow Data within the Depot *

Table 4.6.2 Emission factors for Buses *

Table 4.6.3 Predicted Depot Vehicular Emission Rates for NO2, CO, RSP and SO2 *

Table 4.6.4 Background Concentrations for NO2, CO, RSP and SO2 *

Table 4.6.5 Predicted Maximum 1-hr NO2, CO and SO2 and, 24-hr RSP concentrations *

Table 4.7.1 Parameters employed in CALINE4 model *

Table 4.7.2 Traffic flow at Nearby Roads for Year 2016 *

Table 4.7.3 Annual Average Air Pollutant Concentrations for NO2, CO and RSP *

Table 4.7.4 Predicted maximum 1-hr NO2, CO and 24-hr RSP concentrations at 9mPD level *

Table 4.8.1 Predicted maximum cumulative 1-hr NO2, CO and 24-hr RSP concentrations *

Table 5.2.1 Acceptable Noise Levels for day, evening and night periods *

Table 5.2.2 ANLs for Construction other than Percussive Piling, dB(A) *

Table 5.2.3 ANLs for daytime, evening and night-time periods *

Table 5.4.1 Representative NSRs closest to the project site *

Table 5.5.1 Inventory of PMEs during Foundation Construction *

Table 5.5.2 Inventory of PMEs during Superstructure Construction *

Table 5.5.3 Predicted Corrected Noise Levels at NSRs due to construction works *

Table 5.7.1 Inventory of Operational Activities within the Depot *

Table 5.7.2 Predicted Facade Noise Levels at NSRs due to Depot Operations *

Table 5.8.1 Bus Flow Data within the Depot *

Table 5.8.2 Predicted Facade Noise Levels at NSRs due to On-Site Vehicular Noise *

Table 5.9.1 Traffic flow Data at Nearby Roads for Year 1999 (All Traffic) *

Table 5.9.2 Traffic flow Data at Nearby Roads for Year 2016 (All Traffic) *

Table 5.9.3 Traffic flow Data at Nearby Roads (Buses only) *

Table 5.9.4 Predicted Noise Levels due to Off-Site Traffic during Night Return *

Table 5.9.5 Predicted Noise Levels due to Off-Site Traffic during Morning Leaving *

Table 5.10.1 Listing of Quiet PME items *

Table 5.11.1 Major Noise Sources *

Table 6.4.1 Estimated Volumes of Excavated Material *

Table 6.4.2 Estimated C&D Material Production *

Table 6.5.1 Chemicals to be Used for the Operation of the Depot *

Table 6.5.2 Waste Produced from the Operation of the Depot *

Table 7.4.1 Chemicals to be Used at the Bus Depot *

Table 8.2.1 Maximum Number of People Present in the Proposed Bus Depot *

Table 8.3.1 Storage capacities and Dangerous Goods Classification of Fuel Oils *

 Table 8.4.1a Physical Properties of a Typical diesel Oil 76

Table 8.4.1b Physical Properties of Kerosene 77

Table 8.4.2a Summary of Hazards in CRC Oil Terminal Identified in HAZOP Study 78

Table 8.4.3a Summary of Hazards at New World First Bus Permanent Depot Identified 80

Table 8.5.2a Pool Fire Dimensions 84

Table 8.5.3a Consequence Modelling Results from CRC Oil Terminal 86

Table 8.5.3b Consequence Modelling Results of Diesel Storage 92

Table 8.6.1a Summary of Significant Hazards to New World First Bus Permanent Depot 95

Table 8.6.2a Frequency Estimation for Scenarios B1-3, P1 and F1: Major fires at the oil terminal 97

Table 8.6.2b UK Petrol Spills – Historical Data 99

Table 8.6.2c Frequencies of Spills 100

Table 8.6.2d Frequencies of Hazardous Event Outcomes for FB2 100

Table 8.6.2e Frequency of Hazardous Event Outcome for FB1 101

Table 8.6.2f Frequency Estimation for Scenarios FB1 and FB2: Major fires at the NWFB Depot 101

Table 8.6.3a Assessment of Impact of Smoke Ingress into Bus Depot 104

Table 8.6.3b Assessment of Impact of Fire on Government Depot 104

Table 8.7.1a Risk Results affecting the Bus Depot 107

Table 8.7.1b Risk Results from Bus Depot 107

Table 8.7.1c Individual Risks Results 107

Table 8.8a Risk Mitigation Measures 109

Table 9.2.1 Environmentally Sensitive Areas and Population Protected 115

Table 9.2.2 Summary of Environmental Benefits 116

List of Figures

Figure 1.1

Site Location

Figure 4.1

Locations of Representative Air Sensitive Receivers (ASRs)

Figure 4.2a

Predicted 1-hour TSP concentrations at Ground Level (Dust Emission)

Figure 4.2b

Predicted 1-hour TSP concentrations at 4.5m above Ground Level (Dust Emission)

Figure 4.2c

Predicted 24-hour TSP concentrations at Ground Level (Dust Emission)

Figure 4.2d

Predicted 24-hour TSP concentrations at 4.5m above Ground Level (Dust Emission)

Figure 4.3a

Predicted 1-hour NO2 concentrations at Ground Level (Depot Emission)

Figure 4.3b

Predicted 1-hour NO2 concentrations at 5m above Ground Level (Depot Emission)

Figure 4.3c

Predicted 1-hour NO2 concentrations at 15m above Ground Level (Depot Emission)

Figure 4.3d

Predicted 1-hour NO2 concentrations at 30m above Ground Level (Depot Emission)

Figure 4.4a

Predicted 1-hour CO concentrations at Ground Level (Depot Emission)

Figure 4.4b

Predicted 1-hour CO concentrations at 5m above Ground Level (Depot Emission)

Figure 4.4c

Predicted 1-hour CO concentrations at 15m above Ground Level (Depot Emission)

Figure 4.4d

Predicted 1-hour CO concentrations at 30m above Ground Level (Depot Emission)

Figure 4.5a

Predicted 1-hour SO2 concentrations at Ground Level (Depot Emission)

Figure 4.5b

Predicted 1-hour SO2 concentrations at 5m above Ground Level (Depot Emission)

Figure 4.5c

Predicted 1-hour SO2 concentrations at 15m above Ground Level (Depot Emission)

Figure 4.5d

Predicted 1-hour SO2 concentrations at 30m above Ground Level (Depot Emission)

Figure 4.6a

Predicted 24-hour RSP concentrations at Ground Level (Depot Emission)

Figure 4.6b

Predicted 24-hour RSP concentrations at 5m above Ground Level (Depot Emission)

Figure 4.6c

Predicted 24-hour RSP concentrations at 15m above Ground Level (Depot Emission)

Figure 4.6d

Predicted 24-hour RSP concentrations at 30m above Ground Level (Depot Emission)

Figure 4.7a

Predicted 1-hour NO2 concentrations at 5.5mPD Level (Vehicular Emission – Night-time)

Figure 4.7b

Predicted 1-hour NO2 concentrations at 9mPD Level (Vehicular Emission – Night-time)

Figure 4.7c

Predicted 1-hour NO2 concentrations at 19mPD Level (Vehicular Emission – Night-time)

Figure 4.8a

Predicted 1-hour CO concentrations at 5.5mPD Level (Vehicular Emission – Night-time)

Figure 4.8b

Predicted 1-hour CO concentrations at 9mPD Level (Vehicular Emission – Night-time)

Figure 4.8c

Predicted 1-hour CO concentrations at 19mPD Level (Vehicular Emission – Night-time)

Figure 4.9a

Predicted 24-hour RSP concentrations at 5.5mPD Level (Vehicular Emission – Night-time)

Figure 4.9b

Predicted 24-hour RSP concentrations at 9mPD Level (Vehicular Emission – Night-time)

Figure 4.9c

Predicted 24-hour RSP concentrations at 19mPD Level (Vehicular Emission – Night-time)

Figure 4.10a

Predicted Cumulative 1-hour NO2 concentrations at 5.5mPD Level (Depot and Vehicular Emissions)

Figure 4.10b

Predicted Cumulative 1-hour NO2 concentrations at 9mPD Level (Depot and Vehicular Emissions)

Figure 4.10c

Predicted Cumulative 1-hour NO2 concentrations at 19mPD Level (Depot and Vehicular Emissions)

Figure 4.11a

Predicted Cumulative 1-hour CO concentrations at 5.5mPD Level (Depot and Vehicular Emissions)

Figure 4.11b

Predicted Cumulative 1-hour CO concentrations at 9mPD Level (Depot and Vehicular Emissions)

Figure 4.11c

Predicted Cumulative 1-hour CO concentrations at 19mPD Level (Depot and Vehicular Emissions)

Figure 4.12a

Predicted Cumulative 24-hour RSP concentrations at 5.5mPD Level (Depot and Vehicular Emissions)

Figure 4.12b

Predicted Cumulative 24-hour RSP concentrations at 9mPD Level (Depot and Vehicular Emissions)

Figure 4.12c

Predicted Cumulative 24-hour RSP concentrations at 19mPD Level (Depot and Vehicular Emissions)

Figure 5.1a

Existing Bus Ingress/Egress Routeing

Figure 5.1b

Year 1999 Traffic Flows (At Early Morning Peak (0545-0645) and Mid-Night Peak (2300-0000)

Figure 5.1c

Existing Bus Ingress/Egress Flows at Mid-Night Peak (2300 - 0000)

Figure 5.1d

Existing Bus Ingress/Egress Flows at Early Morning Peak (0545 - 0645)

Figure 5.2

Locations of Representative Noise Sensitive Receivers (NSRs)

Figure 5.3

Proposed Bus Ingress/Egress Routeing

Figure 5.4

Year 2016 Forecast Flows (At Early Morning Peak (0545-0645) and Mid-Night Peak (2300-0000)

Figure 5.5

Bus Ingress/Egress Flows at Mid-Night Peak (2300 - 0000)

Figure 5.6

Bus Ingress/Egress Flows at Early Morning Peak (0545-0645)

Figure 8.1

Layout Plan of CRC Oil Terminal

Figure 8.2a

Event Tree of Major Fires at oil Terminal – Base Case

Figure 8.2b

Event Tree of Major Fires at oil Terminal – Mitigated Case

Figure 8.3

Event Tree of Major Fires at Bus Depot

Figure 8.4a

FN Curve: Hazards posed by the CRC Oil Terminal – Base Case

Figure 8.4b

FN Curve: Hazards posed by the CRC Oil Terminal After Mitigation Measures

Figure 8.5

FN Curve: Hazards posed by Diesel Storage

LIST OF APPENDICES

Appendix A

Preliminary Layout plans

Appendix B

A Typical FDM Output File at 4.5m above Ground Level

Appendix C

Details of Depot Emission Rates Calculation

Appendix D

A Typical ISCST Output File at 15m above Ground Level

Appendix E

A Typical CALINE4 Output File at 9mPD Level

Appendix F

Details of Construction Noise Assessment

Appendix G

Details of Depot Operation Noise Assessment (Day-time)

Appendix H

Details of Depot Operation Noise Assessment (Night-time)

Appendix I

Details of On-Site Vehicular Noise Assessment (Night Return)

Appendix J

Details of On-Site Vehicular Noise Assessment (Morning Leaving)

Appendix K

Endorsement of Traffic Data

Appendix L1

Details of Off-Site Traffic Noise Assessment (All Traffic - Night Return) (Year 1999)

Appendix L2

Details of Off-Site Traffic Noise Assessment (All Traffic - Night Return) (Year 2016)

Appendix M1

Details of Off-Site Traffic Noise Assessment (All Traffic - Morning Leaving) (Year 1999)

Appendix M2

Details of Off-Site Traffic Noise Assessment (All Traffic - Morning Leaving) (Year 2016)

Appendix N1

Details of Off-Site Traffic Noise Assessment (Buses Only - Night Return) (Existing Scenario)

Appendix N2

Details of Off-Site Traffic Noise Assessment (Buses Only - Night Return) (Future Scenario)

Appendix O1

Details of Off-Site Traffic Noise Assessment (Buses Only - Morning Leaving) (Existing Scenario)

Appendix O2

Details of Off-Site Traffic Noise Assessment (Buses Only - Morning Leaving) (Future Scenario)

Appendix P

Details of Calculations of Noise Contribution

Appendix Q

HAZOP Work Sheets

Appendix R

Past Incidents

Appendix S

Assessment of Smoke Ingress

Appendix T

Pool Fire Analysis

  1. INTRODUCTION

    1. Background of the Project

      1. The project is proposed to provide a new permanent depot building for bus parking, maintenance facilities and provision of office accommodation. The new depot is proposed to replace the existing bus depot located at Chai Wan Road and the existing temporary servicing/parking site, which has only parking, refueling and washing facilities, located to the south-west of the proposed project site. The existing bus depot and the temporary servicing/parking site will be maintained in operation throughout the course of the Project.

      2. The New World First Bus (NWFB) has commissioned Westwood Hong & Associates Ltd (WHA) to undertake an Environmental Impact Assessment (EIA) of the proposed New World First Bus Permanent Depot.

      3. The proposed Permanent Depot project is classified as a designated project under Schedule of the Environmental Impact Assessment Ordinance (EIAO) which comes into operation on 1st April 1998. Thus, this project must comply in full with the requirements of the EIAO process. This EIA Report is prepared in response to the EIA Study Brief No. ESB-034/1999 issued by the EPD on 23 July 1999 for the proposed New World First Bus Permanent Depot at Chai Wan. The Study Brief was issued based on information provided in the Project Profile submitted by NWFB on 14 June 1999 under the statutory provisions of the EIAO.

  2. project description

    1. Site Selection

      1. The selection of site for the development of a multi-storey bus depot is in connection with the franchise to operate 59 Hong Kong Island and 29 Cross Harbour Tunnel bus routes by the Hong Kong Government. Within the tender document (Tender Reference: BDC 70/202-1) issued by the Transport Department in February 1998, a site of about 11,500 sqm was identified. Subsequently, after the award of the tender to NWFB, it was agreed with the Government that, rather than the rectangular site initially proposed, it would be more efficient to development a square site. An application was made to change the site to that currently proposed.

    3. Site Location and Site History

      1. The proposed bus depot is located to the north of the Chai Wan Cargo Handling Area and to the north-east of the existing temporary servicing/parking site (Figure 1.1). The proposed site is used as a temporary car park. According to Outline Zoning Plan No. S/H20/8, the proposed site is zoned as "Industrial".

      2. Concurrent projects near the proposed site as stated in the explanatory statement of the OZP No. S/H20/8 include the site at the junction of Shing Tai Road and Chong Fu Road which has been reserved for the joint Government departmental depot including an ambulance depot and, sites located to the west of the cargo handling basin along Shing Tai Road reserved for further industrial development including a lorry park/motor vehicle repair workshop.

    4. Design of the Depot

      1. The proposed depot development covers a site area of 11,900m2 with total GFA of approximately 60,000m2 and building height of approximately 43m.

      2. The proposed depot is a multi-storey building comprising various provisions to facilitate different repairing and maintenance operation needs. The depot will have an estimated population of 320 persons (maximum) in works/maintenance area and 180 persons (maximum) in office area. Details are shown in Table 2.3.1.

        3. Table .1 Maximum No. of persons present within the proposed depot building

        Time

        Works / Maintenance Area

        Office

        Day (08:00 – 18:00)

        320

        180

        Evening & night (18:00 – 02:00)

        140

        20

        Night (02:00 – 08:00)

        120

        5

      4. The following Table 2.3.2 illustrates the provision of the depot facilities. Preliminary floor plans of the proposed depot are given in Appendix A.

        5. Table .2 Facility Provisions of the proposed depot

        Facilities

        Location

        Bus parking

        1/F, 2/F, 4/F, 6/F & 8/F

        Re-fueling and washing area

        G/F

        Test lanes

        G/F

        Engine/gear box/axle assembly workshop

        G/F

        Battery charging

        G/F

        Workshop

        G/F

        Shower and changing facilities

        G/F

        Maintenance area (including sunken pit, steaming & painting)

        G/F & 1/F

        Tyre changing workshop

        G/F

        Air valve and air-con workshop

        1/F

        Fibre glass workshop

        1/F

        Maintenance office

        1/F

        Training rooms

        3/F

        Canteen & kitchen

        4/F

        Staff recreational area

        5/F & 6/F

        Function room

        6/F

        Administration office

        7/F

      5. Apart from the above facilities, the project also provides the following facilities:-

  • the provision of treatment facilities (such as oil interceptor/grease traps) for handling bus wash wastewater, grease-laden water from maintenance area and used radiator water.

  • the provision to collect engine oil and chemicals for treatment at licensed treatment centre.

 

  2. Scope of the assessment

    1. Purpose of the Study

      1. The purpose of this EIA Study is to evaluate the potential environmental impacts arising from the construction and operation of the proposed project and its related activities, to develop and specify measures necessary to mitigate particular adverse impacts which are identified, and to determine the environmental acceptability of the residual impacts of the overall project.

    2. Broad Study Objectives

      1. The main objectives of the EIA study are clearly defined in the EPD Study Brief and given below:

    1. to describe the proposed project and associated works together with the requirements for carrying out the proposed project;

    2. to identify and describe the elements of the community and environment likely to be affected by the proposed project, and/or likely to cause adverse impacts to the proposed project, including both the natural and man-made environment;

    3. to identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;

    4. to propose the provision of infrastructure or mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the project;

    5. to identify, predict and evaluate the residual (i.e. after practical mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operational phases of the project in relation to the sensitive receivers and potential affected uses;

    6. to identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the project which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;

    7. to investigate the extent of side-effects of proposed mitigation measures that may lead to other forms of impacts;

    8. to identify constraints associated with the mitigation measures recommended in the EIA study;

    9. to design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.

    1. Structure of the Report

      1. The following technical assessments have been undertaken and detailed in the relevant parts for both the construction and operational phases of the proposed depot development:

    • Section 4 - Air Quality Impact Assessment;

    • Section 5 - Noise Impact Assessment;

    • Section 6 - Waste Management Impact Assessment;

    • Section 7 - Land Contamination Assessment; and

    • Section 8 - Hazard Impact Assessment;

      1. Appropriate Environmental Monitoring and Audit (EM&A) and Environmental Management System (EMS) requirements are identified based on the findings of the EIA study. By the implementation of the EM&A requirements, it can be ensured that the recommendations in the EIA Study are correctly incorporated and the environmental impacts are adequately controlled, whereas the EMS ensures the new bus depot can achieve satisfactory environmental performance.

      2. In addition, an Environmental Management Plan (EMP) has been developed as a stand-alone document which forms part of the final EIA Study Report. The EMP was proposed to confirm the effectiveness of all the proposed mitigation measures.

        3. Air Quality

      3. Air impact during both the construction and operational phases of the project has been assessed (Section 4). Fugitive dust emission is the main air pollutant to the sensitive receivers during the construction phase of the proposed depot.

      4. The air emission from the operational activities, including buses performing normal manoeuvres within the depot compound, engine testing and painting activities will be the major air pollutant sources during the operational phase.

        5. Noise

      5. Noise during both the construction and operational phases of the project has been assessed (Section 5). Noise from site works, use of the powered mechanical equipment (PME) and other civil works, and structural building works was evaluated for the construction phase assessment.

      6. The operational phase considered all significant noise sources from the proposed depot, including buses travelling and parking, engine testing, maintenance operations and other workshop operations, and the off-site traffic flow generated by the proposed depot with buses leaving and returning to the proposed depot during early morning and night-time.

        7.  

        Waste Management

      7. Section 6 deals with the assessment of wastes arising from the construction and operational phases of the project. The construction phase assessment examined excavated material, general construction waste, chemical waste and general refuse. A certain amount of chemical waste (mainly of engine oil and lubricants from maintenance operations) or scraps will be generated in various operations or workshops during operational phase.

        8. Land Contamination

      8. An assessment of the potential for contamination of land from spills, leakage and other events during the operation of the new plant is provided in Section 7. Particular attention was paid to the operational practices, waste management strategies, precautionary measures for prevention of contamination problems and emergency procedures for the new depot.

        9. Hazard

      9. Section 8 includes hazard assessments for both the on-site and off-site risks associated with the operation of the proposed depot and the adjacent CRC Oil Terminal.

 

    1. Project Implementation Programme

      1. The proposed project will be planned and designed by private consultants and contractors.

      2. The EIA process has be started in June 1999 and to be completed by around end of 1999. The envisaged construction period of the project will be from around the beginning of 2000 to 2001. The depot is expected to be commissioned by August 2001.

 

  2. air quality

    1. Introduction

      2. Background

      1. This report presents the key findings of an air quality assessment of the proposed bus depot. It is prepared as part of an EIA study carried out under the Environmental Impact Assessment Ordinance (EIAO) for the New World First Bus Co Ltd (NWFB).

      2. A new bus depot is proposed to replace the existing bus depot located at Chai Wan Road and the existing temporary servicing/parking site located to the south-west of the proposed project site. A Project Profile and an application for a Study Brief were submitted by NWFB on 14 June 1999. In accordance with the EIAO, the EPD issued a Study Brief No. ESB-034/1999 on 23 July 1999 which specifies the following study requirements for air quality issues:

    • a construction dust assessment;

    • a depot emission assessment to assess the air emissions from the operational activities to nearby Air Sensitive Receptors (ASRs); and

    • a vehicular emission assessment to assess the vehicular emissions from off-site traffic to nearby ASRs.

Purpose and Objectives

      1. This Section of the Report aims to satisfy the requirements in Clause 3.3.1 of the Study Brief. The primary objectives are:

    • to identify existing and planned ASRs potentially affected by atmospheric emissions from the new bus depot;

    • to review the baseline air quality at representative ASRs;

    • to present the operating scenarios of the planned facilities and the emissions inventory;

    • to describe the assessment methodology and the predicted impacts;

    • to evaluate the predicted impacts on air quality against recognised criteria; and

    • to recommend mitigation measures where necessary to achieve acceptable air quality.

    2. Legislation and Standards

      3. Air Pollution Control Ordinance

      1. Air quality is regulated under the provisions of the Air Pollution Control Ordinance (APCO). Under the current legislation, the Hong Kong Air Quality Objectives (HKAQO) provides the statutory AQOs for different air pollutants, as shown in Table 4.2.1.

        2. Table .1 Hong Kong Air Quality Objectives

         

        Concentration in micrograms per cubic metre (i)

        Pollutant

        1 Hour (ii)

        8 Hours (iii)

        24 Hours (iii)

        3 Months (iv)

        1 Year (iv)

        Sulphur Dioxide

        800

        		  

        350

        		  

        80

        Total Suspended Particulate

        		    

        260

        		  

        80

        Respirable Suspended Particulate (v)

        		    

        180

        		  

        55

        Carbon Monoxide

        30000

        10000

        		      

        Nitrogen Dioxide

        300

        		  

        150

        		  

        80

        Photochemical Oxidants (as ozone) (vi)

        240

        		        

        Lead

        		      

        1.5

        		  

        Notes : (i) Measured at 298K(25o C) and 101.325 kPa (one atmosphere).

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

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

        (iv) Yearly and three monthly figures calculated as arithmetic means.

        (v) Respirable suspended particulate means suspended particles in air with nominal aerodynamic diameter of 10 micrometres and smaller.

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

        Construction Dust Criteria

      2. According to Annex 4 of the "Technical Memorandum on Environmental Impact Assessment Process" (EIA-TM), the Air Sensitive Receptors (ASRs) should meet the hourly TSP concentration of 500m g/m3 for construction dust impact assessment.

    4. Baseline Conditions

      1. The dominant air pollution sources in the vicinity included road traffic emission from Island East Corridor (IEC) and Shing Tai Road.

      2. Since opening the existing temporary servicing/parking site (which is closer to the nearest ASRs than the proposed new depot at Chong Fu Road) at Shing Tai Road in February 1999, it is understood that NWFB has not received any complaints concerning the air emissions generated by the vehicles traveling to and from the existing temporary servicing/parking site.

    5. Representative Air Sensitive Receivers (ASRs)

      1. The Air Sensitive Receivers (ASRs) closest to the proposed project site have been selected as the representative ASRs. They are shown in the following Table 4.4.1 and Figure 4.1.

      Table .1 Representative ASRs closest to the project site

      Representative ASRs

      Horizontal Distance from ASRs to the site boundary (m) (approximately)

      SQ1

      HK Technical College (Chai Wan) Staff Quarters

      210

      SQ2

      HK Technical College (Chai Wan) Staff Quarters

      180

      HFC1

      Block 50, Heng Fa Chuen

      230

      HFC2

      Block 15, Heng Fa Chuen

      770

      HFC3

      Block 17, Heng Fa Chuen

      660

      TWE1

      Tsui Shou House, Tsui Wan Estate

      430

      TWE2

      Tsui Hong House, Tsui Wan Estate

      450

      TC1

      HK Technical College (Chai Wan)

      200

      I1

      "I" zone located to the south-west of the site

      0

      I2

      "I" zone located to the further south-west of the site

      80

       

    7. Dust Dispersion Assessment

      8. Methodology

      1. The TSP concentration at the project site has been predicted by using the USEPA Fugitive Dust Model (FDM). This model had been thoroughly validated by the USEPA and is generally accepted by the Environmental Protection Department (EPD). FDM is a dispersion modeling program to estimate pollutant concentrations and depositions from sources, according to Gaussian Plume formulation, but the model has been specifically adapted to incorporate an improved gradient-transfer deposition algorithm.

      2. The meteorological data employed in this assessment are provided by the Hong Kong Observatory. These data on hourly wind directions, wind speeds, Pasquill stability class (A to F) and mixing heights were collected from Kai Tak Station for Year 1992.

      3. The TSP emission rate of the construction site is taken as 1.04 x 10-5 g/m2-s, which is reference from the AP-42. The 1-hour and 24-hour TSP concentrations have been computed for the ground level and 4.5m above ground level.

      4. The predicted concentrations including background concentrations were presented in contour maps, plotted by employing the program Surfer by Golden Software. The background concentration is taken as the annual average concentration of 84m g/m3 from Central/Western area as stated in the Air Quality in Hong Kong.

        5. Predicted Dust Dispersion Concentrations

      5. The contour plots of 1-hour and 24-hour TSP concentrations at the nearby ASRs are shown in Figures 4.2a - 4.2b and 4.2c - 4.2d for the ground level and 4.5m above ground level. The predicted concentrations will satisfy the HKAQO limits as described in Section 4.2. The levels above will be subject to lower pollutant concentrations. The FDM typical output file at ground level is given in Appendix B.

      6. The worst affected level is predicted at ground floor level and the maximum 1-hour and 24-hour TSP concentrations at the nearby ASRs are summarised in Table 4.5.1. The predicted maximum concentrations at the nearby ASRs comply with the TMEIA and HKAQO limits. Mitigation measures and environmental monitoring are recommended in Sections 4.9and 4.10 to ensure the air quality will be satisfied within the site boundary.

       

      Table .1 Predicted Maximum 1-hour and 24-hour TSP concentrations at ground floor level

       

      Predicted concentrations*(in m gm-3)

      Representative ASRs

      1-hour TSP

      24-hour TSP

      SQ1

      HK Technical College (Chai Wan) Staff Quarters

      170

      97

      SQ2

      HK Technical College (Chai Wan) Staff Quarters

      182

      100

      HFC1

      Block 50, Heng Fa Chuen

      160

      92

      HFC2

      Block 15, Heng Fa Chuen

      <120

      <90

      HFC3

      Block 17, Heng Fa Chuen

      <120

      <90

      TWE1

      Tsui Shou House, Tsui Wan Estate

      120

      <90

      TWE2

      Tsui Hong House, Tsui Wan Estate

      120

      <90

      TC1

      HK Technical College (Chai Wan)

      180

      102

      I1

      "I" zone located to the south-west of the site

      240

      145

      I2

      "I" zone located to the further south-west of the site

      210

      124

      * Background concentration level of 84 m gm-3 is included

    8. Depot Emission Assessment

      9. Pollutant Emission Sources within the Depot

      1. The potential emission sources identified from the depot operations include engine testing, painting and exhaust emissions from workshops. Given that only insignificant amount of the above emissions is anticipated, the nearby ASRs will not be adversely affected by the emissions. The exhaust emissions generated by bus movements are the main air pollutants that may cause adverse effect to the nearby ASRs. The exhaust emissions includes mainly nitric oxides (NOx), carbon monoxide (CO), respirable suspended particulates (RSP) and sulphur dioxide (SO2). The NO2 concentration is taken to be 20% of the NOx level, as adopted for other similar projects and accepted by the EPD.

        2. Dispersion Modeling Program

      2. The pollutant concentrations due to the operation of the bus depot at the nearby ASRs have been predicted by using the USEPA Industrial Source Complex Short Term (ISCST) model. ISCST3 is a dispersion modeling program to estimate pollutant concentrations or depositions from sources, according to Gaussian dispersion principles.

        3.  

         

        Bus Flow data

      3. The bus flow data within the depot is estimated by the traffic consultant (MVA (HK) Ltd). A summary of the estimated number of buses entering/leaving during night return and early morning leaving is given in Table 4.6.1 below.

        4. Table .1 Bus Flow Data within the Depot

         

        Number of Buses/hour
         

        During Night Return

        During Morning Leaving

        Floor Levels

        Entering

        Leaving

        Entering

        Leaving

        G/F

        143

        74

        98

        98

        2/F

        69

        55

        78

        98

        4/F

        55

        41

        58

        78

        6/F

        41

        27

        38

        58

        8/F

        27

        -

        -

        38

         

        Emission Factors

      4. The emission factors due to the activities of buses are summarized in Table 4.6.2 below. Fleet Average Emission Factors produced by the "FAEF" Model for year 1998 and idling factors recommended by EPD are adopted in the calculations of NOx, CO, RSP and SO2 for buses.

        5. Table .2 Emission factors for Buses

         

        Emission factors

        Buses Activities

        NOX

        CO

        SO2

        RSP

        Idling (g/min/vehicle)

        2.0

        2.0

        -

        0.042

        Traveling (g/km)

        11.71

        8.89

        1.36

        1.38

        Emission Rates from the Depot Operations

      5. The predicted emission rates of NO2, CO, RSP and SO2 due to the depot operation at each floor levels are given in the following Table 4.6.3. Details of calculations are given in Appendix C.

        6.  

         

         

         

         

         

        Table .3 Predicted Depot Vehicular Emission Rates for NO2, CO, RSP and SO2

         

        Emission Rates

        Floor Levels

        NO2

        CO

        SO2

        RSP

        G/F

        0.0196 g/s

        0.0856 g/s

        0.0056 g/s

        6.8 x 10-3 g/s

        1/F

        0.0144 g/s

        0.0628 g/s

        0.0042 g/s

        5.2 x 10-3 g/s

        2/F

        0.0096 g/s

        0.0424 g/s

        0.0028 g/s

        3.2 x 10-3 g/s

        4/F

        0.0076 g/s

        0.0328 g/s

        0.0021 g/s

        2.4 x 10-3 g/s

        6/F

        0.0052 g/s

        0.0232 g/s

        0.0015 g/s

        2.0 x 10-3 g/s

        Roof

        0.0060 g/s

        0.0256 g/s

        0.0023 g/s

        2.4 x 10-3 g/s

        Methodology

      6. The meteorological data employed in this assessment are provided by the Hong Kong Observatory. These data on hourly wind directions, wind speeds, Pasquill stability class (A to F) and mixing heights were collected from Kai Tak Station for Year 1992.

      7. Given that the site is located in Chai Wan area, the "Urban" mode has been selected as the Dispersion Mode in the model.

      8. The NO2, CO, RSP and SO2 concentrations were computed for the nearby ASRs at ground, 5m, 15m and 30m above local ground level. The predicted concentrations including background concentrations were presented in contour maps, plotted by employing the program Surfer by Golden Software.

        9. Background Pollutant Concentrations

      9. The background pollutant concentrations are taken as the annual average concentrations from the full year monitoring results as given in the Air Quality in Hong Kong 1997 and are summarized in Table 4.6.4.

Table .4 Background Concentrations for NO2, CO, RSP and SO2

 

Air Pollutants
 

NO2

CO

SO2

RSP

Background concentrations (µgm-3 )

58 (a)

1095 (b)

18 (c)

51 (d)

Notes : (a) NO2 – annual average at Central/Western area

(b) CO – annual average at Mong Kok area

    1. SO2 – annual average at Central/Western area

    2. RSP – annual average at Central/Western area

 

Predicted Depot Emission Concentrations

      1. The contour plots for the predicted 1-hour concentrations of NO2, CO and SO2 and 24-hour concentration of RSP at the nearby ASRs are shown in Figures 4.3a - 4.3d, 4.4a - 4.4d, 4.5a - 4.5d and 4.6a – 4.6d from ground level to 30m above local ground level. The ISCST typical output file at 15m above ground level is given in Appendix D.

      2. The worst affected levels are predicted at 15m above ground level for I1 and 30m for the other representative ASRs. The maximum 1-hour NO2, CO and SO2 and, 24-hour RSP concentrations at the nearby ASRs are summarised in Table 4.6.5. Results indicate that at the nearby ASRs will satisfy the HKAQO limits.

        3. Table .5 Predicted Maximum 1-hr NO2, CO and SO2 and, 24-hr RSP concentrations

         

        Predicted maximum concentrations* (in m gm-3)

        Representative ASRs

        1-hr NO2

        1-hr CO

        1-hr SO2

        24-hr RSP

        SQ1

        HK Technical College

        (Chai Wan) Staff Quarters

        67 (30)†

        1133 (30)

        21 (30)

        51.7 (30)

        SQ2

        HK Technical College

        (Chai Wan) Staff Quarters

        68 (30)

        1139 (30)

        21 (30)

        51.6 (30)

        HFC1

        Block 50, Heng Fa Chuen

        66 (30)

        1131 (30)

        20.5 (30)

        51.5 (30)

        HFC2

        Block 15, Heng Fa Chuen

        < 65 (30)

        1110 (30)

        19 (30)

        51.3 (30)

        HFC3

        Block 17, Heng Fa Chuen

        < 65 (30)

        1115 (30)

        19.5 (30)

        51.3 (30)

        TWE1

        Tsui Shou House, Tsui Wan Estate

        < 65 (30)

        1118 (30)

        < 20 (30)

        51.2 (30)

        TWE2

        Tsui Hong House, Tsui Wan Estate

        65 (30)

        1118 (30)

        < 20 (30)

        51.3 (30)

        TC1

        HK Technical College

        (Chai Wan)

        68 (30)

        1138 (30)

        21 (30)

        51.6 (30)

        I1

        "I" zone located to the south-west of the site

        115 (15)

        1340 (15)

        34 (15)

        54.4 (15)

        I2

        "I" zone located to the further south-west of the site

        79 (30)

        1190 (30)

        24 (30)

        52 (30)

        *Background concentrations are included

        † 67 (30) - Predicted concentration level of 67m gm-3 at 30m above ground level

      3. In view of the predicted NO2, CO, RSP and SO2 concentrations at the nearby ASRs complying with the HKAQO limits, it is not required to adopt any mitigation measures against depot emissions.

    2. Road Traffic Vehicular Emission Assessment

      3. Dispersion Modeling Program

      1. The air impacts caused by the vehicular emissions have been predicted by employing CALINE4 model which is a line source air quality model developed by the California Department of Transport. The prediction model is based on the Gaussian diffusion equation and employs a mixing zone concept to characterize pollutant dispersion over the roadway.

        2. Methodology

      2. The major pollutants emitted by vehicles include Nitrox (NOx), Carbon Monoxide (CO) and Respirable Suspended Particulates (RSP). The emission factors for these pollutants have been calculated according to the EPD’s Fleet Average Vehicle Emission Factors.

      3. The hourly NO2, CO and RSP concentrations were computed for the levels at 5.5mPD, 9mPD and 19mPD. According to Trinity Consultants Inc, the supplier of the CALINE4 software, the 24-hour averages of RSP could be estimated by multiplying the maximum 1-hour concentration with multiplication factor of 0.4. This factor is accepted by the regulatory agencies in the USA.

      4. NO2 is assumed to be behaved as an inert gas. The concentrations for NO2 are taken to be 20% of the predicted NOx results. These assumptions have been commonly adopted by the Air Modeling Section of EPD when modeling air pollutant impacts from open road traffic emissions on neighboring sensitive receptors using the CALINE4 model.

      5. The parameters employed in the CALINE4 model are given in Table 4.7.1. These parameters are the worst-case meteorological data which take into account the night-time conditions and are agreed with the EPD.

        6. Table .1 Parameters employed in CALINE4 model

        Parameters employed in CALINE4

        Value

        Wind Speed

        1m/s

        Stability Class

        F

        Ambient Temperature

        25 degree C

        Mixing Height

        500m

        Wind Direction Standard Deviation

        6 degree

        Aerodynamic Roughness Coefficient

        100cm

        Pollutant Settling Velocity

        0 cm/s

        Pollutant Deposition Velocity

        0 cm/s

         

         

        Traffic Flow Data

      6. Vehicular emissions from Island Eastern Corridor and other main roads during night return and morning leaving have been considered in the assessment. The traffic flow data for Year 2016 prepared by the traffic consultant (MVA (HK) Ltd) is summarised in the following Table 4.7.2 and presented in Figure 5.4.

        7. Table .2 Traffic flow at Nearby Roads for Year 2016

         

        During night return

        During Morning Leaving
         

        Veh/hr

        % HGV

        Veh/hr

        % HGV

        Island East Corridor

        1940

        42%

        2575

        30%

        Shing Tai Road

        511

        48%

        234

        79%

        Chong Fu Road

        46

        6%

        147

        74%

        Wing Tai Road

        1171

        22%

        749

        43%

      7. Background concentrations for CO, NO2 and RSP are taken as the annual average concentrations stated in the Air Quality in Hong Kong, as shown in Table 4.7.3.

        8. Table .3 Annual Average Air Pollutant Concentrations for NO2, CO and RSP

         

        Pollutants
         

        NO2

        CO

        RSP

        Background concentrations (µgm-3 )

        58 (a)

        1095 (b)

        51 (c)

        Notes : (a) NO2 – annual average at Central/Western area

        (b) CO – annual average at Mong Kok area

        (c) RSP – annual average at Central/Western area

        Predicted Road Traffic Vehicular Emission Concentrations

      8. The predicted 1-hour NO2, 1-hour CO and 24-hour RSP concentrations are shown in Figures 4.7a - 4.7c, 4.8a - 4.8c and 4.9a - 4.9c at 5.5mPD, 9mPD and 19mPD levels, with the CALINE4 typical output files at 9mPD level given in Appendix E.

      9. The worst affected level is predicted at 9mPD level and the maximum NO2 , CO and RSP concentrations at the nearby ASRs are summarised in Table 4.7.4. Results indicate that the predicted NO2 , CO and RSP concentrations at the nearby ASRs are within the HKAQO limits from ground level to 19mPD level. The ASRs on the levels above are located further away from the roads and would be subject to lower pollutant concentrations.

        10.  

         

        Table .4 Predicted maximum 1-hr NO2, CO and 24-hr RSP concentrations at 9mPD level

         

        Predicted maximum concentrations* (in m gm-3)

        Representative ASRs

        1-hr NO2

        1-hr CO

        24-hr RSP

        SQ1

        HK Technical College

        (Chai Wan) Staff Quarters

        120

        1610

        62

        SQ2

        HK Technical College

        (Chai Wan) Staff Quarters

        120

        1610

        62

        HFC1

        Block 50, Heng Fa Chuen

        96

        1410

        58

        HFC2

        Block 15, Heng Fa Chuen

        130

        1620

        63

        HFC3

        Block 17, Heng Fa Chuen

        145

        1850

        68

        TWE1

        Tsui Shou House, Tsui Wan Estate

        97

        1430

        59

        TWE2

        Tsui Hong House, Tsui Wan Estate

        98

        1440

        59

        TC1

        HK Technical College

        (Chai Wan)

        150

        1850

        68

        I1

        "I" zone located to the south-west of the site

        115

        1410

        61

        I2

        "I" zone located to the further south-west of the site

        110

        1550

        61

        *Background concentrations are included

      10. In view of the predicted 1-hour NO2 , CO and RSP concentrations at the nearby ASRs complying with the HKAQO limits, it is not required to adopt any mitigation measures.

    4. Cumulative Impacts

      1. The contour plots for the cumulative impacts due to the depot emission and the vehicular emission on the road are presented in Figures 4.10a – 4.10c for 1hr NO2 , Figures 4.11a – 4.11c for 1-hr CO and Figures 4.12a – 4.12c for 24-hr RSP at 5.5mPD, 9mPD and 19mPD. As a conservative approach, the worst predicted cumulative concentrations of NO2 , CO and RSP as shown in Table 4.8.1 are based on numerical summation of the predicted concentrations from the depot emission and vehicular emission assessment. The worst predicted concentrations at levels are presented in the contour plots.

        2. Table .1 Predicted maximum cumulative 1-hr NO2, CO and 24-hr RSP concentrations

         

        Predicted concentrations* (in m gm-3)

        Representative ASRs

        1-hr NO2

        1-hr CO

        24-hr RSP

        SQ1

        HK Technical College

        (Chai Wan) Staff Quarters

        129

        1648

        62.7

        SQ2

        HK Technical College

        (Chai Wan) Staff Quarters

        130

        1654

        62.6

        HFC1

        Block 50, Heng Fa Chuen

        104

        1446

        58.5

        HFC2

        Block 15, Heng Fa Chuen

        137

        1635

        63.3

        HFC3

        Block 17, Heng Fa Chuen

        152

        1870

        68.3

        TWE1

        Tsui Shou House, Tsui Wan Estate

        104

        1453

        59.2

        TWE2

        Tsui Hong House, Tsui Wan Estate

        105

        1463

        59.3

        TC1

        HK Technical College

        (Chai Wan)

        160

        1893

        68.6

        I1

        "I" zone located to the south-west of the site

        172

        1655

        64.4

        I2

        "I" zone located to the further south-west of the site

        131

        1645

        62

        *Background concentrations are included

         

      2. The predicted cumulative concentrations are well within the HKAQO limits, there will be no adverse impact on the ASRs. It is noted that the vertical concentration profiles of RSP are not identical in shape as other pollutants since the prediction period of RSP is 24 hours while others are 1 hour.

       

    6. Mitigation Measures

      7. Construction Phase

      1. Although the predicted results of the dust assessment are well within the HKAQO limits, the following control measures are recommended according to Air Pollution Control (Construction Dust) Regulation to minimize dust emissions for the construction works:-

    • Watering program - Watering is a common and effective control method because the facility to provide water and the necessary equipment are readily available at most construction sites. For a construction site, watering is most effective if applied at the frequently trafficked areas including the entrance, exit and access road. A watering program with a frequency of four times daily shall be provided to give a full coverage of these frequently trafficked areas. Wheel-washing facilities including a "wheel-washing trough" and water jet spraying should also be provided at the exit of the site. Such a watering program, if effectively carried out, is capable of reducing dust emissions by about 50 per cent.

    • Good Site Practice - Stockpiles of dusty materials shall be adequately enclosed and be stored as far as practicable away from sensitive receptors. The load carried by vehicles should be covered by impervious sheeting to ensure no leakage of dusty materials from the vehicles. Enclosed chutes or hoists should be used to lower debris from upper floors.

Operational Phase

      1. Since no adverse air pollution impacts are anticipated due to the operation of the bus depot, no mitigation measures are required. Nevertheless, a proper bus routeing has been proposed to avoid buses from passing through the section of Shing Tai Road facing Heng Fa Chuen. Therefore, the vehicular emissions to the residents at Heng Fa Chuen can be minimised.

 

    2. Environmental Monitoring & Audit (EM&A) Requirements

      1. A stand-alone EM&A Manual has been developed to define the scope of the EM&A and EMS requirements for the construction and operation of the project to achieve satisfactory environmental performance. The EM&A and EMS requirements are summarised in the following.

        2. EM&A Requirements

      2. During the construction phase, continuous surveillance of the implementation of dust mitigation measures shall be carried out on a weekly basis to ensure effective control of dust emissions.

      3. The monitoring of air quality during operational phase is considered not necessary as the depot will be properly designed so that no adverse impact will be affecting the nearby ASRs.

        4. EMS Requirements

      4. The following EMS requirements are recommended for the operation of the bus depot:-

    1. Depot Ventilation

    • The fresh air inlets should be at the location that they can capture fresh air of a quality which is comparable to the ambient background level. They should be away from any major air pollution sources such as busy roads or polluted air outlets.

    • The exhaust air outlets should be located away from nearby residents or other receptors to avoid causing an air pollutant nuisance.

    • Inside the depot, the fresh air delivery outlets should be positioned at a low level to discharge fresh air towards the occupants, whereas the extraction openings should be placed at high level. The fresh air outlet and the extraction openings should be placed as far away from each other as possible, and should be configured to avoid air short circulation.

    • Inspection and maintenance of the ventilation system should be carried out at regular intervals, to ensure proper operation of the ventilation system and minimize breakdown time.

    • A proper fan operation schedule should be provided and the schedule should be reviewed once every three months, or a pollution level interlocked fan operation system, to ensure that there is always sufficient ventilation.

    • Idling Emissions - instruction should be given to all drivers using the depot to switch off the vehicle engines while waiting.

    2. Buses Emission

    • A fleet rejuvenation programme involving 500 new environmentally friendly buses to be implemented.

    • A refurbishment programme comprising engine conversion programme, catalytic converter installation and saloon renovation, to reduce exhaust emissions of relatively old NWFB air-conditioned buses as much as possible and to pursue a less polluted environment.

    • NWFB will explore the introduction of Euro III engines, the most advanced engine design which is being tested in Europe; for delivery of buses in 2000 and beyond.

    • Engines of 20 old air-conditioned buses, which are below Euro II standard, will be upgraded towards the equivalent of Euro II standard by replacing the old with new engines. Adding to the engine conversion, catalytic converters (CATs) will be installed onto the 177 older buses to enable a further reduction of exhausts by 45-50%.

    1. Ultra-Low Sulphur Diesel (ULSD)

    • NWFB will explore the introduction of Ultra-Low Sulphur Diesel (ULSD). ULSD is being used in the UK by FirstGroup, the UK partner of NWFB and has been proven to be as environmentally friendly as liquefied petroleum gas, when used with Euro II engines.

 

    1. Summary and Conclusions

      2. Construction Phase

      1. According to the dust impact assessment, the predicted dust emissions during the construction phase comply with the statutory criterion. Together with the adoption of the proper dust control measures, it is envisaged that the nearby ASRs would not be adversely affected by the construction dust.

        2. Operational Phase

      2. The results of the quantitative studies show that the predicted air pollutant concentrations are well within the HKAQO limits at the nearby ASRs due to the emissions from the operation activities of the proposed new bus depot and, from the off-site bus traffic. No adverse impacts are anticipated with insignificant air pollutants contributions from the new bus depot to the neighbourhood.

  2. Noise

    1. Introduction

      2. Background

      1. This report presents the key findings of an assessment of the potential noise impacts arising from the construction and operational phases of the proposed bus depot. It is prepared as part of an EIA study carried out under the Environmental Impact Assessment Ordinance (EIAO) for the New World First Bus Co Ltd (NWFB).

        2. Purpose and Objectives

      2. This Section of the Report aims to satisfy the requirements in Clause 3.3.2 of the Study Brief. The primary objectives are:

    • to describe the existing noise environment in the vicinity of the proposed bus depot;

    • to identify existing and planned noise sensitive receivers (NSRs) potentially affected by noise emissions from the proposed bus depot;

    • to present the operating scenarios of the planned facilities and the emissions inventory;

    • to describe the assessment methodology used to predict construction and operational noise impacts and the predicted noise impacts;

    • to evaluate the predicted noise impacts against recognised criteria;

    • to recommend mitigation measures where necessary to achieve acceptable noise levels; and

    • to propose noise monitoring and audit programme for construction and operational phases of the proposed project.

    1. Legislation and Standards

      1. The principal legislation for the control of construction and operation noise is given in the Noise Control Ordinance (NCO). The guidelines for the assessment of construction and operational noise are given in the Environmental Impact Assessment Ordinance (EIAO). Various Technical Memoranda (TMs), which stipulate the control approaches and criteria have been issued under the NCO and EIAO. The following TMs are applicable to the control of noise from construction activities and plant operation:-

    • Technical Memorandum on Environmental Impact Assessment Process (EIA-TM);

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

    • Technical Memorandum on Noise from Construction Work in Designated Areas (DA-TM);

    • Technical Memorandum on Noise From Percussive Piling (PP-TM); and

    • Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM).

Construction Noise Criteria

      1. The daytime construction work should comply with the guidelines in the EIA-TM.

      2. Noise standards for daytime construction activities are given in Table 1B of the EIA-TM. The noise standards are dependent on the uses of the NSRs. The day-time construction noise (on any day not being a Sunday or general holiday) should be limited to 75dB(A) (Leq, 30-mins) at the sensitive residential buildings with openable windows and, 70dB(A) and 65dB(A) (during examinations) at the school and educational buildings in the neighbourhood, as given in Table 5.2.1. EIA-TM states that the noise criteria for construction or decommissioning of designated projects, shall be met as far as practicable. All practicable mitigation measures shall be exhausted and the residual impacts are minimized.

        3. Table .1 Acceptable Noise Levels for day, evening and night periods

         

         

        Noise Standards, dB(A), Leq (30 mins)

        Uses

        0700 to 1900 hours on any day not being a Sunday or general holiday

        1900 to 0700 hours or any time on Sundays or general holiday

        All domestic premises including temporary housing accommodation

        75

        (see Note 3)

        Hotels and hostels

        75

        (see Note 3)

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

        70

        65

        (during exam.)

        (see Note 3)

        Note 3: The criteria laid down in the relevant technical memoranda under the Noise Control Ordinance for designated areas and construction works other than percussive piling may be used for planning purpose. A Construction Noise Permit (CNP) shall be required for the carrying out of the construction work during the period.

      3. GW-TM will cover the use of powered mechanical equipment (PME) including compressors, bored piling, concrete pumps, concrete mixers, generators, excavators, etc.

      4. DA-TM governs construction works to be carried out within a Designated Area during restricted hours. It covers Prescribed Construction works including erection or dismantling of formwork or scaffolding; loading, unloading or handling of rubble, wooden boards, steel bars, wood or scaffolding material; and hammering. As the entire reclamation site lies outside the Designated Areas, DA-TM does not apply. Construction activities during restricted hours will need to comply with GW-TM only.

      6. A Construction Noise Permit (CNP) is required for any construction work to be carried out during restricted hours, i.e. 1900 to 0700 hours on any day not being a general holiday and at any time on a general holiday. Despite any description or assessment made in this EIA Report on construction noise aspects, there is no guarantee that a CNP will be issued for the project construction. The Noise Control Authority will consider a well-justified CNP application, once filed, for construction works within restricted hours as guided by the relevant Technical Memoranda issued under the Noise Control Ordinance. The Noise Control Authority will take into account of contemporary conditions / situations of adjoining land uses and any previous complaints against construction activities at the site before making his decision in granting a CNP. Nothing in this EIA Report shall bind the Noise Control Authority in making his decision. If a CNP is to be issued, the Noise Control Authority shall include in it any condition he thinks fit. Failure to comply with any such conditions will lead to cancellation of the CNP and prosecution action under the NCO.

      7. The control of percussive piling is governed at all times by PP-TM.

      8. The NCO requires that the construction noise levels to comply with the Acceptable Noise Level (ANL) as given in GW-TM. The ANL is dependent on the Area Sensitivity Rating for the NSR.

      9. The ANLs from GW-TM for Construction Works other than Percussive Piling are given in Table 5.2.2 with no correction applied to allow for noise contribution from construction work associated with more than one CNP. The Authority should be approached for clarification of an appropriate correction for multiple permit situations.

        10. Table .2 ANLs for Construction other than Percussive Piling, dB(A)

         

        Area Sensitivity Rating (ASR)

        Time Period

        A

        B

        C

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

        60

        65

        70

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

        45

        50

        55

      10. In addition, other noise regulations, Noise Control (Hand held percussive breakers) Regulations and Noise Control (Air Compressors) Regulations govern the noise from hand held breakers and air compressors on compliance with the relevant noise emission standards and the fixing of noise emission labels.

        11. Traffic Noise Criterion

      11. In the EIA-TM, an L10 (1 hour) of 70 dB(A) is used to assess the peak hour traffic noise from a planned new road on domestic premises (this becomes 65 dB(A) for educational institutions). These noise limits apply to premises relying on openable windows as primary means of ventilation. To ascertain the off-site traffic noise impact caused by the operation of the Depot, a comparison between the noise contributions from the buses using the Depot after 15 years of operation and that under the prevailing situation during the maximum activities hours will be used; and it is considered as insignificant if the difference is less than 1.0 dB(A).

        12. Operational Noise Criteria

      12. The EIA-TM specifies that noise from fixed sources under planning should be 5dB(A) below the ANL listed in Table 2 of the IND-TM or the prevailing background noise level. Therefore, the potential noise impact due to the proposed bus depot shall be 5dB(A) less than the value given in Table 5.2.3, i.e. 60dB(A) during day-time and 50dB(A) during night-time as ASR for the identified noise sensitive receivers is assumed to be "B" for the purpose of this EIA.

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

Table .3 ANLs for daytime, evening and night-time periods

 

Area Sensitivity Rating (ASR)

Time Period

A

B

C

Day (0700 to 1900 hours) and evening (1900 to 2300 hours)

60

65

70

Night (2300 to 0700 hours)

50

55

60

 

    2. Baseline Conditions

      1. The dominant noise sources in the vicinity included road traffic noise from Shing Tai Road, rail noise from MTR tracks and operation noise from Chai Wan Cargo Handling Area. The measured noise levels at the site boundaries are in the range of 57 – 59dB(A) during the site inspection.

      2. It should be noted that the re-fueling and washing facilities within the proposed depot will be instead of that currently used in existing temporary servicing/parking site at Shing Tai Road and thus no additional traffic movements will be generated on Shing Tai Road. The time period when major traffic movements are generated by the depot facility will not coincide with the operation of the Hong Kong Technical College.

      3. The existing temporary servicing/parking site is located at and with an ingress/egress point at Shing Tai Road, Chai Wan. The existing bus ingress/egress routings to/ from the bus depot are shown in Figure 5.1a to 5.1c. During night time, buses are returning to the depot for washing and refueling.

      4. The buses returning from other districts to the bus depot are mainly via the Island Eastern Corridor (IEC) and Shing Tai Road. For the other buses coming from Siu Sai Wan and Chai Wan Area, the routeing is via Wing Tai Road, Shun Tai Road, Shing Tai Road and back to the bus depot. According to the survey results, the proportions of the buses coming from other districts via IEC and Siu Sai Wan/ Chai Wan Area are about 75% and 25% respectively.

      5. After washing and refueling, only a small amount of the returning buses are parked in the temporary servicing/parking site because of its small size. Most of the buses leave the depot and park at the other bus terminals. There are approximate 75% of the leaving buses are via Shing Tai Road, Shun Tai Road and IEC to other districts. The rest 25% of the leaving buses are via Shing Tai Road and Wing Tai Road to park at the bus terminals in Siu Sai Wan/ Chai Wan Area.

      6. Since opening the existing temporary servicing/parking site at Shing Tai Road in February 1999, which is closer to the Technical College than the proposed new depot at Chong Fu Road, it is understood that New World First Bus have not received any complaints concerning the noise generated by the vehicles being serviced at the site.

    4. Representative Noise Sensitive Receivers

      1. The Noise Sensitive Receivers (NSRs) closest to the proposed project site have been selected as representative NSRs. They are shown in the following Table 5.4.1 and Figure 5.2.

        2. Table .1 Representative NSRs closest to the project site

        Representative NSRs

        Floors

        SQ1

        HK Technical College (Chai Wan) Staff Quarters (western facades)

        G/F - 25/F

        SQ2

        HK Technical College (Chai Wan) Staff Quarters (western facades)

        G/F - 25/F

        SQ3

        HK Technical College (Chai Wan) Staff Quarters (eastern facades*)

        G/F - 25/F

        SQ4

        HK Technical College (Chai Wan) Staff Quarters (eastern facades*)

        G/F - 25/F

        HFC1

        Block 50, Heng Fa Chuen

        G/F - 20/F

        HFC2

        Block 15, Heng Fa Chuen

        G/F - 20/F

        HFC3

        Block 17, Heng Fa Chuen

        G/F - 20/F

        TWE1

        Tsui Shou House, Tsui Wan Estate

        G/F - 30/F

        TWE2

        Tsui Hong House, Tsui Wan Estate

        G/F - 30/F

        TC1

        HK Technical College (Chai Wan)

        G/F - 8/F

        Note: * Eastern facades of the HK Technical College (Chai Wan) Staff Quarters were installed with fixed windows

      2. The eastern facades of the HK Technical College (Chai Wan) Staff Quarters are installed with fixed windows so that the indoor environment of SQ3 and SQ4 are unlikely to be affected. For the NSRs with openable windows on the western façade, the depot site will be totally screened by the building itself such that the depot will not be visible when viewed from any openable windows at the western facades. According to the GW-TM, a negative correction of 10dB(A) shall be applied to the noise prediction for SQ1 and SQ2 regarding noise impact caused by the ‘screened’ depot site.

      3. The HK Technical College (Chai Wan) (TC1) is installed with air-conditioners so that the occupants of the teaching classrooms and laboratories will not rely on openable windows as primary ventilation.

       

    6. Construction Noise Assessment

      7. Construction Noise Prediction Procedure

      1. The methodology for assessing the construction noise other than percussive piling is based on GW-TM, as summarised in the following:-

        2. i) To identify the affected NSRs within the Study Area;

        ii) To identify the phasing of construction work and, locations and required number of the construction plant items;

        iii) To obtain the sound power levels in dB(A) of the construction equipment from the GW-TM;

        iv) To determine the distance from the effective noise source location (or "notional source position") to the NSRs and distance attenuations (from geometric spreading and other absorption effects where appropriate), barrier corrections and reflection corrections at the NSR as prescribed in the GW-TM;

        v) To calculate the Corrected Noise Level (CNL) which will be generated by the construction work at the NSRs;

        vi) To propose direct mitigation measures, if necessary, to minimise the impact by the construction work in order to comply with the stipulated noise limits.

        Construction Schedule

      2. According to the project schedule supplied by NWFB, the construction programme will span about 20 months, beginning in January 2000 and ending in August 2001.

        3. Plant Inventory of Construction Equipment (PMEs)

      3. The inventories of the construction equipment (Powered Mechanical Equipment, or PMEs) expected to be used during foundation & sub-structure and building construction stages of the construction phase is summarised in Tables 5.5.1 and 5.5.2. The plant inventories listed in these tables have been confirmed to be practical and practicable for completing the works within the construction programme. Different stages of the construction works will be carried out in separate period of time. The maximum sound power level (SWL) to be employed for the noise assessment is 129dB(A).

        4. Table .1 Inventory of PMEs during Foundation Construction

        Element

        Equipment

        Reference

        SWL (dB(A))

        No. of units

        Foundation

        Bored Piling (Oscillator)

        165

        115

        9
         

        Generator, silenced

        102

        100

        2
         

        Excavator

        081

        112

        2
         

        Lorry

        141

        112

        4
         

        Crawler Crane

        048

        112

        12
         

        Reverse Circulation Driller

        166

        100

        6
         

        Concrete Lorry Mixer

        044

        109

        2
         

        Dump Truck

        067

        117

        1
         

        Poker

        170

        113

        1
         

        Compactor

        050

        105

        1
             

        Sub-SWL = 128 dB(A)

         

        Table .2 Inventory of PMEs during Superstructure Construction

        Element

        Equipment

        Reference

        SWL (dB(A))

        No. of units

        Group 1

        Compressor < 10 m3/min

        001

        100

        2
         

        Concrete pump

        047

        109

        1
         

        Generator, silenced

        102

        100

        2
         

        Compactor

        050

        105

        2
         

        Excavator

        081

        112

        3
         

        Lorry

        141

        112

        3
         

        Concrete Lorry Mixer

        044

        109

        1
             

        Sub-SWL = 121 dB(A)

        Group 2

        Tower Crane

        049

        95

        1
         

        Hoist

        122

        95

        1
             

        Sub-SWL = 98 dB(A)

        Group 3

        Bar Bender

        021

        90

        2
         

        Saw

        201

        108

        2
         

        Planer

        171

        117

        2
             

        Sub-SWL = 121 dB(A)

        Group 4

        Poker

        170

        113

        2
             

        Sub-SWL = 116 dB(A)

         

        Predicted Construction Noise Impacts

      4. The noise impacts due to the construction of the proposed bus depot using the plant inventory as shown in Tables 5.5.1 and 5.5.2 are predicted in this section. The objective is to assess the project feasibility during this planning stage and to identify if there is any potential constraint on the works programme or the use of the construction equipment.

      6. To preserve conservatism, the likely noise screening effects are ignored in the noise prediction, e.g. the newly-constructed GIC building locating between the site and the Staff Quarters of HKTC and, the planned Government Departmental Depot building locating between the site and Heng Fa Chuen. However, noise screening effect due to the hoarding has been taken into account in the noise prediction.

      7. The following Table 5.5.3 lists the NSRs, their setback distances and the predicted CNLs due to the construction works.

        8. Table .3 Predicted Corrected Noise Levels at NSRs due to construction works

        Representative NSRs

        Distance to Notional Source Position (m)

        Predicted CNLs (dB(A))

        SQ1

        HK Technical College (Chai Wan) Staff Quarters

        206

        67

        SQ2

        HK Technical College (Chai Wan) Staff Quarters

        209

        67

        HFC1

        Block 50, Heng Fa Chuen

        267

        75

        TWE1

        Tsui Shou House, Tsui Wan Estate

        466

        69

        TC1

        HK Technical College (Chai Wan)

        200

        70

         

      8. The above assessment results show that the predicted CNLs comply with the noise criteria stipulated in Section 5.2. The construction work for the proposed bus depot is feasible, without causing any adverse noise impact on the nearby NSRs. Details of calculations for the construction works with the greatest SWL are given in Appendix F.

      9. It should be pointed out that the TC1 at HK Technical College has its teaching classrooms and laboratories already fitted with air-conditioners and with no need to rely on openable windows as primary ventilation. The existing insulation provided with minimum 6mm glazing is expected to be adequate for providing an acceptable indoor environment.

       

    8. Operational Noise Sources

      1. The assessment of operational noise impact includes the following:-

    • bus / car wash;

    • test lane;

    • battery charging;

    • workshops;

    • maintenance areas

    • blacksmith workshop;

    • tyre changing;

    • bus refueling;

    • engine axle workshop;

    • bus travelling and parking within the depot; and

    • off-site bus traffic, during night return and early morning leaving.

    1. Depot Operational Noise Assessment

      2. Noise Prediction Procedure

      1. The methodology for assessing the operational noise is based on IND-TM, as summarised in the following:-

        2. i) To identify the affected NSRs within the Study Area;

        ii) To identify the noise sources and multiple number of the activity operating;

        iii) To obtain the sound power levels in dB(A) of the each activity based on the measurement at the existing bus depot;

        iv) To determine the distance from the noise source location to the NSRs and distance attenuations (from geometric spreading and other absorption effects where appropriate), barrier corrections and reflection corrections at the NSR as prescribed in the IND-TM;

        v) To calculate the Corrected Noise Level (CNL) which will be generated by the operational activities at the NSRs;

        vi) To propose direct mitigation measures, if necessary, to minimise the impact by the construction work in order to comply with the stipulated noise limits.

         

        Inventory of Operational Activities

      2. The inventory of operational activities within the depot at each floor levels during day-time (0700-2300) and night-time (2300-0700) are summarised in the following Table 5.7.1. The noise data were collected from noise testing conducted in the existing bus depot in Chai Wan.

        3. Table .1 Inventory of Operational Activities within the Depot

           

        SWL

        SPL(int)

        No. of Sources

        Activities

        Floor

        (dB(A))

        (dB(A))

        Day-time

        Night-time

        Bus/car wash

        G/F

        88.4

        -

        2

        4

        Test lane

        G/F

        87.9

        -

        2

        1

        Battery charging

        G/F

        -

        74.1

        1

        1

        Workshop

        G/F

        -

        82.6

        1

        1

        Maintenance area/ engine testing

        G/F

        -

        77.8

        10

        5

        Blacksmith workshop

        G/F

        -

        73.6

        1

        1

        Tyre changing lane

        G/F

        97.6

        -

        1

        1

        Bus refueling

        G/F

        82.0

        -

        1

        4

        Engine axle workshop

        1/F

        -

        83.6

        1

        0

        Workshop

        1/F

        -

        82.6

        1

        0

        Maintenance area/ engine testing

        1/F

        -

        77.8

        1

        0

        Bus parking

        2/F

        87.8

        -

        2

        2

        Bus parking

        4/F

        87.8

        -

        2

        2

        Bus parking

        6/F

        87.8

        -

        2

        2

        Bus parking

        Roof

        87.8

        -

        2

        2

        Predicted Operational Noise Impact

      3. The predicted facade noise levels at the representative NSRs are in the range of 40 – 53dB(A) during day-time and 36 – 50dB(A) during night-time. These predicted noise levels comply with the noise criteria stipulated in Section 5.2. The predicted facade noise levels at the NSRs are summarised in the following Table 5.7.2. Details of calculations are given in Appendices G and H for day-time and night-time.

      Table .2 Predicted Facade Noise Levels at NSRs due to Depot Operations

         

      Predicted Noise Levels (dB(A))

      Representative NSRs

      Floors

      Day-time

      Night-time

      SQ1

      HK Technical College (Chai Wan) Staff Quarters

      G/F – 25/F

      40

      36

      SQ2

      HK Technical College (Chai Wan) Staff Quarters

      G/F – 25/F

      39 - 40

      36

      HFC1

      Block 50, Heng Fa Chuen

      G/F – 20/F

      53

      50

      TWE1

      Tsui Shou House, Tsui Wan Estate

      G/F – 30/F

      42

      38

      TC1

      HK Technical College (Chai Wan)

      G/F – 8/F

      40

      -

    2. On-Site Vehicular Noise Assessment

      1. The noise assessment for the movement of buses within the depot when buses returning at mid-night and leaving early in the morning is based on the methodology recommended in the British Standard BS 5228 Part I, Noise Control on Construction and Open Site, 1997.

        2. Bus Flow data

      2. The bus flow data within the depot are provided by the Traffic Consultant (MVA (HK) Ltd). A summary of the anticipated number of buses entering/leaving during mid-night return and early morning leaving is given in Table 5.8.1 below. These bus figures are anticipated to be the worst case scenario within 15 years upon the commissioning of the bus depot.

        3. Table .1 Bus Flow Data within the Depot

         

        Number of Buses/hour
         

        During Night Return

        During Morning Leaving

        Floor Levels

        Entering

        Leaving

        Entering

        Leaving

        G/F

        143

        74

        98

        98

        1/F

        69

        69

        98

        98

        2/F

        69

        55

        78

        98

        4/F

        55

        41

        58

        78

        6/F

        41

        27

        38

        58

        Roof

        27

        -

        -

        38

         

        Predicted Noise Impact due to On-Site Vehicular Noise

      3. The predicted facade noise levels at the representative NSRs are in the range of 25 – 42dB(A) during night return and 23 – 42dB(A) during morning leaving. These predicted noise levels comply with the noise criteria stipulated in Section 5.2. The predicted facade noise levels at the NSRs are summarised in the following Table 5.8.2. Details of calculations are given in Appendices I and J for night return and morning leaving.

        4. Table .2 Predicted Facade Noise Levels at NSRs due to On-Site Vehicular Noise

           

        Predicted Noise Levels (dB(A))

        Representative NSRs

        Floors

        Night Return

        Morning Leaving

        SQ1

        HK Technical College (Chai Wan) Staff Quarters

        G/F – 25/F

        25 – 29

        25 – 30

        SQ2

        HK Technical College (Chai Wan) Staff Quarters

        G/F – 25/F

        30

        31 – 32

        HFC1

        Block 50, Heng Fa Chuen

        G/F – 20/F

        42

        42

        TWE1

        Tsui Shou House, Tsui Wan Estate

        G/F – 30/F

        26 - 29

        23 - 28

      4. The predicted on-site vehicular noise levels are negligible as compared with the off-site traffic noise levels to be presented in the following Section.

      5. Reverberation of noise within the semi-open bus depot is considered not significant due to the large openings on the side walls.

    3. Off-Site Traffic Noise Assessment

      1. The permanent bus depot will be located at a new site bounded by Chong Fu Road, Road 20/6, Road 20/4 and Road 20/10 and with the ingress via Road 20/10 and egress via Road 20/4. The proposed bus ingress/ egress routing to/from the permanent bus depot is presented in Figure 5.3.

      2. As similar to the existing condition, most of the buses returning to the bus depot will be via IEC and the other buses coming from Siu Sai Wan and Chai Wan Area will via Wing Tai Road. The ingress/ egress routings are the same as for the existing temporary servicing/parking site except returning to the permanent bus depot via Road 20/6. Road 20/6 is much farther from the residential developments at Heng Fa Chuen compared with the ingress/ egress point of the existing temporary servicing/parking site. Therefore, the impact of the noise generated from the returning buses on Heng Fa Chuen will be reduced. The proportions for the buses coming from IEC and Chai Wan Area are assumed to be the same for the existing temporary servicing/parking site.

      3. Bus queuing is anticipated to be not significant at the permanent depot at mid night and will not cause a significant noise impact at the nearby NSRs. It is estimated that the maximum queue for refueling and washing at peak hour at night would be 3 buses. The egress routing of the leaving buses to the other districts and Siu Sai Wan / Chai Wan Area will be used the same routings as for the existing temporary servicing/parking site. However, there will be more buses to be parked in the permanent bus depot and less buses will leave the depot and to be parked at the other bus terminals at mid night. Thus the noise impact at night time would be reduced.

      4. The traffic data used in this noise assessment has been endorsed. A record of the correspondence between MVA and Bus Development Branch, Transport Department is given in Appendix K.

      5. The noise assessment due to the bus traffic at the main roads has been conducted based on the procedures given in the "Calculation of Road Traffic Noise (1988)" (CRTN) and by employing the RoadNoise computer software licensed to use by WS Atkins.

        6.  

        Off-Site Traffic (All Traffic)

      6. Off-site traffic noise from Island Eastern Corridor and other main roads during night return (2300 - 0000) and morning leaving (0545 – 0645) have been considered in the assessment. The traffic flow data for Year 1999 (existing) and 2016 estimated by the Traffic Consultant (MVA (HK) Ltd) are presented in Figures 5.1b and 5.4. The two-way traffic flows adopted in the analysis are summarised in Table 5.9.1and Table 5.9.2. These flows are for the worst case scenario within 15 years upon the commissioning of the bus depot.

        7. Table .1 Traffic flow Data at Nearby Roads for Year 1999 (All Traffic)

         

        During night return

        During Morning Leaving
         

        Veh/hr

        % HGV

        Veh/hr

        % HGV

        Island East Corridor

        1887

        41

        2133

        30

        Shing Tai Road

        428

        49

        189

        75

        Chong Fu Road

        32

        6

        100

        74

        Wing Tai Road

        1072

        22

        625

        43

         

        Table .2 Traffic flow Data at Nearby Roads for Year 2016 (All Traffic)

         

        During night return

        During Morning Leaving
         

        Veh/hr

        % HGV

        Veh/hr

        % HGV

        Island East Corridor

        1940

        42%

        2575

        30%

        Shing Tai Road

        511

        48%

        234

        79%

        Chong Fu Road

        46

        6%

        147

        74%

        Wing Tai Road

        1171

        22%

        749

        43%

        Off-Site Traffic (Buses only)

      7. Additional road noise models have been constructed to predict the noise impact from the main roads with buses only (scenarios with existing temporary servicing/parking site and future new depot). The traffic flow data provided by the Traffic Consultant (MVA (HK) Ltd) are presented in Figures 5.1c, 5.1d, 5.5 and 5.6 and summarised in Table 5.9.3. These flows are for the worst case scenario within 15 years upon the commissioning of the bus depot.

        8.  

        Table .3 Traffic flow Data at Nearby Roads (Buses only)

         

        Traffic Flow Data (vehicles per hour)
         

        During Night Return

        During Morning Leaving
         

        Existing

        Future

        Existing

        Future

        Island East Corridor

        144

        171

        28

        85

        Shing Tai Road

        245

        217

        62

        116

        Road 20/10 (run-in)

        0

        143

        0

        18

        Road 20/4 (run-out)

        0

        74

        0

        98

        Wing Tai Road

        101

        46

        34

        31

        Predicted Noise Impact

      8. The predicted facade noise levels at the representative NSRs due to the off-site traffic in the main roads are summarised in the following Table 5.9.4 and Table 5.9.5. Computer files of the calculations of all traffic at existing and future scenarios are given in Appendices L1 and L2 for night return, Appendices M1 and M2 for morning leaving, and that of buses only at existing and future scenarios are given in Appendices N1 and N2 for night return and Appendices O1 and O2 for morning leaving.

        9. Table .4 Predicted Noise Levels due to Off-Site Traffic during Night Return

         

        PNLs (dB(A)) during Night Return

        Noise Contribution [a] (dB(A))

         

        NSRs

        All Traffic (Year 1999)

        Buses Only (Year 1999)

        All Traffic (Year 2016)

        Buses Only (Year 2016)

        Year 1999

        Year 2016

        Maximum Difference

        SQ1

        69 - 73

        61 - 64

        69 - 73

        62 - 65

        0.71 - 0.75

        0.83 - 0.87

        0.1

        SQ2

        58 - 71

        50 - 64

        58 - 71

        51 - 64

        0.77 – 1.19

        0.89 - 1.16

        0.1

        SQ3

        64 - 65

        59 - 60

        66 - 67

        59 - 60

        1.75 - 1.80

        1.07 - 1.10

        -0.7

        SQ4

        65 - 66

        62 - 63

        67 - 68

        61 - 62

        2.49 - 2.57

        1.36 - 1.40

        -1.2

        HFC1

        63 - 64

        57

        67 - 69

        57 - 58

        1.04 - 1.29

        0.23 - 0.53

        -0.6

        HFC2

        73 - 75

        65 - 67

        73 - 75

        65 - 67

        0.75

        0.85 - 0.87

        0.1

        HFC3

        74 - 77

        65 - 69

        74 - 77

        66 - 70

        0.73

        0.85 - 0.87

        0.1

        TWE1

        70 - 72

        65 - 67

        70 - 72

        64 - 65

        1.70 - 1.80

        0.97 - 1.10

        -0.6

        TWE2

        71 - 72

        64 - 67

        71 - 72

        65 - 67

        1.10 - 1.52

        1.22 - 1.70

        0.2

        Note: [a] Noise Contribution from buses to overall noise levels, L10 (1 hr)

         

        Table .5 Predicted Noise Levels due to Off-Site Traffic during Morning Leaving

         

        PNLs (dB(A)) during Morning Leaving

        Noise Contribution [a] (dB(A))

         

        NSRs

        All Traffic (Year 1999)

        Buses Only (Year 1999)

        All Traffic (Year 2016)

        Buses Only (Year 2016)

        Year 1999

        Year 2016

        Maximum Difference

        SQ1

        69 - 72

        54 - 57

        70 - 73

        59 - 62

        0.15

        0.38 - 0.4

        0.2

        SQ2

        58 - 70

        43 - 57

        58 - 71

        48 - 61

        0.16 - 0.28

        0.42 - 0.53

        0.3

        SQ3

        63 - 64

        52 - 53

        64 - 65

        56 - 58

        0.42 - 0.44

        0.79 - 0.85

        0.4

        SQ4

        64 - 65

        55 - 56

        65 - 66

        58 - 59

        0.57 - 0.60

        0.94 - 0.97

        0.4

        HFC1

        63 - 64

        50 - 51

        65 - 66

        54 - 55

        0.20 - 0.24

        0.25 - 0.40

        0.2

        HFC2

        72 - 74

        58 - 60

        73 - 75

        62 - 64

        0.15

        0.39 - 0.40

        0.2

        HFC3

        73 - 77

        58 - 61

        74 - 77

        63 - 66

        0.13 - 0.15

        0.37 - 0.39

        0.2

        TWE1

        70 - 72

        60 - 62

        70 - 72

        62 - 63

        0.48 - 0.53

        0.56 - 0.61

        0.1

        TWE2

        71 - 72

        60 - 62

        72 - 73

        63 - 66

        0.34 - 0.47

        0.70 – 0.94

        0.5

        Note: [a] Noise Contribution from buses to overall noise levels, L10 (1 hr)

         

      9. The prediction results from the road noise models indicate that the traffic with buses only in the main roads will generally give rise to noise levels well below the predicted noise levels from the traffic with all vehicles during night return and morning leaving. Details of calculations are given in Appendix P.

      10. The increase in the noise contribution caused by the future permanent depot and the existing temporary servicing/parking site has been assessed, with insignificant noise increases in the range of 0 – 0.1 dB(A) for mid-night return and 0.1 – 0.5 dB(A) for early morning leaving (Tables 5.9.3 and 5.9.4). Therefore, the new depot will not cause any significant noise increase to the noise contribution from buses at the NSRs. It must be pointed out that, although there is a slight increase during Early Morning, the depot has also brought about useful noise reductions in the range of -0.6 to -1.1dB(A) during Night Return for NSRs at Heng Fa Chuen, Tsui Wan Estate and Staff Quarter.

    5. Mitigation Measures

      6. Construction Phase

      1. The predicted day-time construction noise levels are well within the criteria stipulated in the EIA-TM. However, the following mitigation measures are recommended to reduce further the construction noise impact:-

Table .1 Listing of Quiet PME items

 

Powered Mechanical Equipment (PME)

Maximum SWL, dB(A) (or SPL at 7m)

Reference

Excavator

104

BS 5228: Part 1: 1997 Table 7

Lorry

105

BS 5228: Part 1: 1997 Table 7

Concrete Pumps

106

BS 5228: Part 1: 1997 Table 9

Concrete Mixers

92

BS 5228: Part 1: 1997 Table 9

Compressors

96

BS 5228: Part 1: 1997 Table 10

Generators

75

GW - TM CNP102

 

      1. Good site practice and noise management can considerably reduce the impact of the construction sites’ activities on nearby NSRs. The following measures should be followed during each phase of construction:

    • only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction programme;

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

    • plant known to emit noise strongly in one direction, should, where possible, be orientated so that the noise is directed away from nearby NSRs;

    • silencers or mufflers on construction equipment should be utilised and should be properly maintained during the construction period;

    • mobile plant should be sited as far away from NSRs as possible; and

    • material stackpiles and other structures should be effectively utilised, where practicable, to screen noise from on-site construction activities.

Operational Phase

      1. The operator of the bus depot should adopt the following mitigation measures to avoid adverse noise impact on the NSRs:-

    • Buses run through the nearby will adhere to the suggested routeing prepared by the Traffic Consultant (MVA (HK) Ltd) (Figure 5.1);

    • Buses will not be allowed to travel on the section of Shing Tai Road facing Heng Fa Chuen during mid-night return and early morning leaving; and

    • Monitoring of operational plant to ensure the source terms derived for the operational noise assessment are achieved both in terms of the vendor’s sound power specifications and the operational and maintenance assumptions.

 

    1. Environmental Monitoring & Audit (EM&A) Requirements

      1. A stand-alone EM&A Manual has been developed to define the scope of the EM&A and EMS requirements for the construction and operation of the project to achieve satisfactory environmental performance. The EM&A and EMS requirements are summarised in the following.

        2. EM&A Requirements

      2. The predicted day-time construction noise levels are well within the criteria stipulated in the EIA-TM. However, a limited amount of day-time noise monitoring for 30 active minutes on a bi-weekly basis shall be carried out. The preferred locations for noise monitoring will be at the HK Technical College (Chai Wan) and Staff Quarters, Heng Fa Chuen and Tsui Wan Estate.

      4. The monitoring of noise during operational phase is considered not necessary as no adverse impacts from the operation of the bus depot are anticipated.

        5. EMS Requirements

      5. The following EMS requirements are recommended for the operation of the bus depot:-

    • Plant Noise Survey – An on-site noise survey should be conducted on completion of commissioning of the new depot at a period of peak demand. Further surveys should be conducted following any significant changes in depot design or operational procedures.

    • To minimise vehicular movement at the roof level during mid-night return and early morning leaving;

    • Fixed Plant List – For the design of fixed plant noise control treatment, the plant noise emanating from workshops, plantrooms, fresh air intake and discharge air grilles shall be controlled to 50dB(A), measured at 1m from the affected façade of the NSRs in the vicinity and the Development. This will meet the (ANL – 5) limit of 50dB(A) during night-time. The major noise sources in the depot are presented in Table 5.11.1. Provisions shall be made to control the plant noise by suitable silencers, acoustic louvres and enclosures. The major noisy plant items, should, where possible, be orientated or screened so that the nearby NSRs do not have direct line of sight. Building structures should be effectively utilised, where practicable, to screen noise from the fixed plant.

Table .1 Major Noise Sources

Level

Noise Sources

G/F

Workshops, Maintenance area, Re-fueling & washing area, Transformer room, Pump rooms, Coin counting, Compressor room, Water Treatment Plant

1/F

Workshops, Maintenance area, Fan rooms, PAU room

2/F

Bus parking space, Fan rooms, AHU room, PAU room, Kitchen

3/F

Upper part of car port, PAU room

4/F

Bus parking space, Fan rooms, PAU room

5/F

PAU room, Upper part of carport

6/F

PAU room, Bus parking space, Fan rooms

7/F

PAU room, Upper part of carport

8/F

Chiller room, Pump rooms, Generator rooms, Lift machine rooms, Bus parking space

 

    2. Summary and Conclusions

      3. Construction Phase

      1. Due to the relatively large setback distances between the construction site and the NSRs, the predicted construction noise levels are well below the relevant criteria prescribed by the EIA-TM.

      2. It is therefore concluded that no substantive construction noise mitigation programme will be required. However, recommendations are given to minimise the noise impact during the construction period.

      3. It is recommended to carry out construction noise monitoring. This would be intended to ensure compliance with the stipulated criteria in EIA-TM.

        4. Operational Phase

      4. The predicted noise levels during the operational phase of the bus depot, including depot operation noise, on-site vehicular noise and off-site traffic noise, are within the stipulated criteria prescribed by the EIA-TM at all identified NSRs. Plant noise will be suitably controlled and is not expected to give rise to any adverse impact.

      5. The off-site traffic noise impact on the nearby NSRs will be minimised by proper routeing to avoid buses passing the section of Shing Tai road facing Heng Fa Chuen during mid-night return and early morning leaving.

 

  2. waste management

    1. Introduction

      1. This Section presents an assessment of the potential environmental impacts from the generation, handling, storage, collection and disposal of wastes arising during the construction and operation of the proposed bus depot. Options for waste minimisation, recycling, storage, collection and disposal of waste have been examined, and measures for minimising the environmental impacts due to waste handling and disposal of wastes are recommended.

    2. Legislation and Standards

      1. The criteria for evaluating potential waste management implications are laid out in Annex 7 of the EIA-TM. The following legislation covers the handling, treatment and disposal of wastes will also be considered in the assessment:-

    • Waste Disposal Ordinance;

    • Waste Disposal (Chemical Waste) (General) Regulation;

    • Crown Land Ordinance;

    • Public Health and Municipal Services Ordinance – Public Cleansing and Prevention of Nuisances (Urban Council) and (Regional Council) By-laws; and

Waste Disposal Ordinance

      1. The Waste Disposal Ordinance (WDO) prohibits the unauthorised disposal of wastes, with waste defined as any substance or article which is abandoned. Construction and demolition (C&D) waste is not directly defined in the WDO but is considered to fall within the category of rade waste". Trade waste is defined as waste from any trade, manufacturer or business, or any waste building, or civil engineering materials, but does not include animal waste.

      2. Under the WDO, wastes can only be disposed of at a licensed site. A breach of these regulations can lead to the imposition of a fine and/or prison sentence. The WDO also provides for the issuing of licences for the collection and transport of wastes. Licences are not, however, currently required to be issued for the collection and transport of C&D waste or trade waste.

        3. Waste Disposal (Chemical) (General) Waste Regulation

      3. Chemical waste as defined under the Waste Disposal (Chemical Waste) (General) Regulation includes any substance being scrap material, or unwanted substances specified under Schedule 1 of the Regulation if such substance or chemical occurs in such a form, quantity or concentration so as to cause pollution or constitute a danger to health or risk of pollution to the environment.

      4. A person should not produce, or cause to be produced chemical wastes unless he is registered with the EPD. Any person who contravenes this requirement commits an offence and is liable, upon conviction for a first offence, to a fine of up to HK$200,000 and to imprisonment for up to 6 months.

      5. Producers of chemical wastes must treat their wastes, utilising on-site plant licensed by the EPD, or have a licensed collector take the wastes to a licensed facility. For each consignment of wastes, the waste producer, collector and disposer of the wastes must sign all relevant parts of a computerised trip ticket. This system is designed to allow the transfer of wastes to be traced from cradle to grave.

      6. The Regulation prescribes the storage facilities to be provided on-site, including labelling and warning signs. To minimise the risks of pollution and danger to human health or life, the waste producer is required to prepare and make available written procedures to be observed in the case of emergencies due to spillage, leakage or accidents arising from the storage of chemical wastes. He must also provide employees with training in such procedures.

        7. Crown Land Ordinance

      7. Construction and demolition materials which are wholly inert may be taken to public filling areas. Public filling areas usually form part of land reclamation schemes and are operated by the Civil Engineering Department (CED). The Crown Land Ordinance requires that public filling licences are obtained by individuals or companies who deliver inert C&D material (or public fill) to public filling areas. The licences are issued by the CED under delegated powers from the Director of Lands.

      8. Individual licences and windscreen stickers are issued for each vehicle involved. Under the licence conditions public filling areas will accept only inert building debris, soil, rock and broken concrete. There is no size limitation on the rock and broken concrete, and a small amount of timber mixed with other suitable materials is permissible. The material should, however, be free from marine mud, household refuse, plastic, metal, industrial and chemical wastes, animal and vegetable matter and any other materials considered unsuitable by the public filling supervisor.

        9.  

        Public Cleansing and Prevention of Nuisances by-laws

      9. These by-laws provide a further control on the illegal tipping of wastes on unauthorised (unlicensed) sites. The illegal dumping of wastes can lead to fines of up to HK$10,000 and imprisonment for up to 6 months.

        10. Additional Guidelines

      10. Other "guideline" documents which detail how the contractor should comply with the regulations are as follows:-

    • Waste Disposal Plan for Hong Kong (December 1989), Planning, Environment and Lands Branch Government Secretarial;

    • Environmental Guidelines for Planning in Hong Kong (1998), Hong Kong Planning and Standards Guidelines, Hong Kong Government;

    • New Disposal Arrangements for Construction Waste (1992), Environmental Protection Department & Civil Engineering Department;

    • Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes (1992), Environmental Protection Department;

    1. Construction Waste

      2. Construction Activities

      1. The construction of the new depot will involve the following construction works:-

    • excavation of sunken pits and fuel storage tanks;

    • foundations & sub-structure; and

    • construction of building.

Potential Sources of Impact

      1. The construction activities will result in the generation of a variety of wastes which can be divided into distinct categories based on their constituents, as follows:-

    • excavated material;

    • construction & demolition waste;

    • chemical waste; and

    • general refuse.

 

Excavated Material

      1. Excavated material is defined as inert virgin material removed from the ground and sub-surface. The types of foundation for the depot building will depend on the intensity of loads, the bearing capacity of the subsoil and the tolerance of the installations on differential settlement. There will be bored piling for the construction of the depot building and excavation of sunken pits and fuel storage tanks. Detailed design information on the bored pile foundation, sunken pits and fuel storage tanks is not available at this stage, however, it is expected that the amount of excavated material arisings will not be significant.

        2. Construction and Demolition Waste

      2. The new depot will include the construction of a multi-storey depot building. The superstructure of the building works will be formed either by structural steel or concrete or a composite of steel and concrete.

      3. Surplus construction material will comprise unwanted materials generated during construction, including rejected structures and materials, materials which have been over ordered or are surplus to requirements and materials which have been used and discarded. Surplus construction material will arise from a number of construction and maintenance activities and may include:-

    • wood from formwork and falsework;

    • equipment and vehicle maintenance parts;

    • materials ad equipment wrappings;

    • unusable/surplus concrete/grouting mixes; and

    • damaged/contaminated construction materials.

      1. The quantity of C&D material to be generated from the construction of the depot will depend on the operating procedure and construction site practices, and cannot be determined at this stage. However, with respect to the nature of construction activities and the types of superstructure, it is anticipated that the quantity will be small. C&D material contains a mixture of inert and non-inert material. The inert portion is "public fill" and the non-inert portion is the C&D waste.

      2. The disposal of bentonite slurry generated during construction works should follow the requirements of ProPECC Note 1/94: Construction Site Drainage.

      3. To conserve the capacities of landfill sites, C&D waste with more than 20% (by volume) inert material should not disposal of at landfills. It is therefore good practice to segregate inert and non-inert materials at the construction sites before disposing of the inert material (or public fill) at public filling areas or other reclamation areas and the degradable waste (C&D waste) at landfills. It should be emphasised that the sorting of C&D materials into public fill and C&D waste should be done on-site as far as possible before disposal.

        4. Chemical Waste

      4. Chemical waste, as defined under the Waste Disposal (Chemical Waste)(General) Regulation, includes any substances being scrap material, or unwanted substances specified under Schedule 1 of the Regulation. A complete list of such substances is provided under the Regulation, however, substances likely to be generated by construction activities for the depot will, for the most part, arise from the maintenance of construction plant and equipment. These may include, but need not be limited to the following:-

    • scrap batteries or spent acid/alkali from the maintenance;

    • used engine oils, hydraulic fluids and waste fuel;

    • spent mineral oils/cleaning fluids from mechanical machinery; and

    • spent solvents/solutions, some of which may be halogenated, from equipment cleaning activities.

      1. Chemical waste may pose serious environmental and health and safety hazards if not stored and disposed of in an appropriate manner as outlined in the Waste Disposal (Chemical Waste)(General) and the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes. These hazards include:-

    • toxic effects to workers;

    • adverse effects on air, water and land from spills;

    • fire hazards; and

    • disruption to sewage treatment works due to damage to the sewage biological treatment system if waste is allowed to enter the sewerage system.

      1. It is difficult to quantify the amount of chemical waste which will arise from the construction activities as it will be highly dependent on the Contractor’s on-site maintenance practices and the numbers of plant and vehicles utilised. However, it is anticipated that the quantity of chemical waste, such as lubricating oil and solvent produced from plant maintenance, will be small and in the order of a few hundred litres per month.

        2.  

        General Refuse

      2. The presence of a construction site with large numbers of workers and site offices and canteens will result in general refuse requiring disposal. This will mainly consist of food wastes, aluminum cans and waste paper.

      3. The storage of general refuse has the potential to give rise to adverse environmental impacts. These include odour if the waste is not collected frequently (e.g. daily), windblown litter, water quality impacts if waste enters water bodies, and visual impact. The site may also attract pests, vermin, and other disease vectors if the waste storage area are not well maintained and cleaned regularly. In addition, disposal of wastes at sites other than approved landfills can also lead to similar adverse impacts at the site.

      4. It is expected that about 100 workers could be working on-site during peak construction period. Based on a waste generation rate of about 0.6 kg per day, it is estimated that the amount of general refuse to be generated daily will be in the order of 60 kg.

    1. Evaluation of Construction Waste Impacts

      1. The nature of wastes arising from the construction of the depot and the potential environmental impacts that may arise from their handling, storage, transport and disposal are discussed below for each waste type.

      2. The assessment of potential environmental impacts associated with waste management is based on the following factors:-

    • type of waste generated;

    • amount of principal waste types generated; and

    • proposed recycling, storage, transport and disposal methods, and the impacts of these methods.

 

Excavated Material

      1. Since the depot is to be located on newly reclaimed land, the excavated material arising from construction of bored pile foundations will consist of previously placed marine sand fill and is expected to have high moisture content. Detailed design of the bored pile foundation is not available at this stage, so it is not possible to quantify the material arisings accurately. However, it is expected that the excavated material can be sent to public filling areas or other reclamation sites for reuse. The estimated volumes of excavated material for different areas are summarised in Table 6.4.1.

        2. Table .1 Estimated Volumes of Excavated Material

        Areas involving Excavation

        Volumes of Excavated Material (m3)

        Sunken Pits

        5,500

        Underground Fuel Storage Tanks

        600

        Piles

        45,000

        Pile Caps

        4,500

        Ground Slab

        4,000

         

        Construction and Demolition Waste

      2. If not properly managed, the storage, handling, transport and disposal of C&D material have the potential to create visual, water, dust and traffic impacts.

      3. The C&D waste will mainly arise from the construction of new buildings and structures. Table 6.4.2 presents the estimated volume of C&D material to be produced by the construction of the depot.

        4. Table .2 Estimated C&D Material Production

        Building

        Dimension (m)

        No. of Storey

        GFA (m2)

        C&D Materials (m3) [a]

        Main Depot Building

        117 x 106

        8

        99,216

        9,922

        Underground Fuel Storage Tanks

        N/A

        Underground

        N/A

        Detailed design information is not available and the likely quantity of C&D materials cannot be determined at this stage

        Note: [a] Generation rate for C&D materials assumed to be 0.1m3m-2 (source reference: Reduction of Construction Waste Final Report, Hong Kong Polytechnic, 1983)

      4. It is recommended that C&D materials should be sorted on-site and the inert material should be used, as far as practicable, for the reclamation. If on-site use is not practicable, the inert C&D material should be delivered to public filling areas.

      5. The disposal of inert C&D material (or public fill) at public filling areas or other reclamation sites is unlikely to raise any long term concerns because of the inert nature of the material. Disposal of C&D waste to licensed landfill will not cause unacceptable environmental impacts. Wherever practical, the production of C&D wastes should be minimised by the careful control of ordering procedures and the segregation of materials. It will also assist in minimising costs should landfill charges be introduced.

      6. C&D wastes currently account for approximately 35% of the annual consumption of limited landfill void available in Hong Kong (although this proportion has varied widely over recent years). Therefore it is important to minimise, wherever possible, the wastes to be disposed of to landfill.

        7. Chemical Waste

      7. The chemical waste to be generated from the construction activities should be transferred away by licensed collectors.

      8. Storage, handling, transport and disposal of chemical waste should be arranged in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Waste published by EPD. Provided with the above practices, the potential environmental impact arising from the handling, storage and disposal of a small amount of chemical wastes generated from the construction activities will be negligible.

        9. General Refuse

      9. The amount of general refuse to be generated is small (approximately 60 kg daily). Provided that the mitigation measures recommended in Section 6.7 are adopted, the environmental impacts caused by storage, handling, transport and disposal of general refuse are expected to be minimal.

    1. Operational Waste

      2. Identification of Waste Generation Activities

      1. The operation of the new depot will involve the following waste generating activities:-

    • operations of the depot;

    • plant maintenance; and

    • office activities.

Potential Sources of Impact

      1. The above activities will result in the generation of a variety of wastes which can be divided into the following categories:-

    • industrial waste;

    • chemical waste;

    • sewage; and

    • general refuse.

      1. The nature and quantity of each of these waste types arising from the operations of the new depot are discussed below.

        2. Industrial Waste

      2. Industrial waste will be generated from maintenance activities. Materials may include scarp metals, packaging materials for spare parts and cleaning materials.

        3. Chemical Waste

      3. Under the terms of the Dangerous Goods Ordinance, no storage of the chemical in the depot is defined as DGs. However, there are battery acids, paints, thinner and some other chemicals kept in individual safe storage areas close to their point of usage.

      4. The types and quantities of chemicals to be used and wastes to be generated from the operation of the depot are given in Tables 6.5.1 and 6.5.2. Chemical wastes will arise from used, surplus and expired chemicals. As discussed for the construction phase, these chemical wastes may pose significant environmental and health and safety hazards if they are not properly managed.

Table .1 Chemicals to be Used for the Operation of the Depot

Facility

Chemical

Quantity stored on-site

Maintenance Area / Workshop

  • Paint

  • Thinner

  • Turpentine

100 litres

50 litres

50 litres

Fuel Storage Tanks

  • Diesel

(Storage Capacity) 100,000 litres

Dangerous Goods Stores

  • Oxygen and Acetylene

Insignificant
 

  • Fibre Glass Material
  
 

- Methyl Ethyl Ketone Peroxide

Insignificant
 

- Acetone

Insignificant
 

  • Sulphuric Acid

Insignificant

 

 

Table .2 Waste Produced from the Operation of the Depot

Facility

Waste

Estimated Annual Quantity

Maintenance Area / Workshop

  • Spent solvent

  • Paint spraying

  • Used engine oil

  • Spent battery

  • Waste lube oil

  • Hydraulic fluids and waste fuel

250 litres

2,000 litres

100,000 litres

300 batteries

20,000 litres

2,500 litres

 

Sewage

      1. Sewage from the operation of the depot includes domestic waste generated by the staff working at the depot and, used water generated from the bus wash facilities and pits.

        2. General Refuse

      2. General refuse will arise from daily activities of staff working at the site. General refuse will include food waste, paper waste and office waste. The storage of general refuse has potential to give rise to adverse environmental impacts. These include odour if waste is not collected frequently, windblown litter and visual impact. The site may also attract pests and vermin if the waste storage area is not well maintained and cleaned regularly.

    2. Evaluation of Operation Waste Impacts

      3. Industrial Waste

      1. The amount of industrial waste to be generated during the operational phase cannot be determined at this stage.

      2. Metals have high scrap value and may be solid for recycling. Other general industrial waste such as packaging materials can be collected together with the general refuse and disposed of at licensed waste transfer or disposal facilities.

      3. Provided that scrap materials are collected regularly, it is not expected that storage, handling, transport and disposal of industrial waste will cause any significant environmental impact.

        4. Chemical Waste

      4. Provided that chemical wastes are managed in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Waste published by EPD, they should not cause unacceptable impacts.

        5. Sewage

      5. Around 80% of the used water from the bus wash facilities will be recycled. Reused water is collected using series of oil (diesel) interceptors and filters integrally designed with the bus wash machine. The sewage collected from the pits will be pretreated by oil interceptors at the depot and the remained sludge slurry will be transported away by licensed collectors. With the above practices, no water quality impact or odour nuisance are envisaged.

        6. General Refuse

      6. About 500 staff will be working at the site during the operational phase of the depot. Based on a daily waste generation rate of about 0.6 kg per person, it is estimated that the amount of general refuse will be in the order of 300 kg d-1.

      7. The amount of general refuse to be generated from the operation of the new depot is small. Provided that the mitigation measures recommended in Section 6.7 are adopted, the environmental impacts caused by storage, handling, transport and disposal of general refuse are expected to be minimal.

    4. Waste Management Plan

      1. This section sets out the waste management plan that are recommended to minimise potential adverse impacts associated with waste arising from the construction and operation of the new depot.

        2. Solid Waste Management

      2. Waste Management Hierarchy – The various waste management options can be categorised in terms of preference from an environmental viewpoint.

    • The options considered to be more preferable have the least impacts and are more sustainable in a long term context. Hence, the hierarchy is as follows:-

    • avoidance and minimisation (i.e. avoiding or not generating waste through changing or improving processes, practices and design);

    • reuse of materials, thus avoiding disposal (generally with only limited reprocessing);

    • recovery and recycling, thus avoiding disposal (although some form of reprocessing is usually required); and

    • treatment and disposal, according to relevant laws, guidelines and good practice.

    • This hierarchy should be used to evaluate waste management options, thus allowing maximum waste reduction and often reducing costs. For example, by reducing of eliminating over-ordering of construction materials, waste is avoided and costs are reduced both in terms of purchasing of raw materials and in disposing of wastes.

      1. Excavated materials – They are not considered likely to cause adverse impacts with respect to their disposal, since they will be delivered to public filling areas or other reclamation sites for reuse. Excavated materials will be segregated from other wastes to avoid possible contamination, thereby allowing reuse on-site or at the public filling areas. The amount of excavated material to be generated from the construction activities will be small.

      2. Construction and Demolition Waste – In order to minimise waste arisings and keep environmental impacts within acceptable levels, the mitigation measures described below will be adopted.

    • Careful design and planning and good site management can minimise over ordering and generation of waste materials such as concrete, mortars and cement grouts. The design of formwork shall maximise the use of standard wooden panels so that high reuse levels can be achieved. Alternatives such as steel formwork or plastic facing should be considered to increase the potential for reuse.

    • The Contractor shall recycle and reuse as much as possible of the C&D material on-site. Proper segregation of wastes into different waste and material types on-site will increase the feasibility that certain components of the waste stream can be recycled by specialised contractors. Concrete and masonry, for example, can be crushed and used as fill and steel reinforcing bar can be used by scrap steel mills. Different areas of the site can be designated for such segregation and storage, depending on site-specific conditions.

    • The remaining inert materials shall be disposed of at public filling areas. Waste containing putrid materials shall be disposed of at landfill. At present, Government is developing a charging policy for the disposal of waste to landfill. When it is implemented, this will provide additional incentive to reduce the volume of waste generated and to ensure proper segregation to allow free disposal of inert material to public filling areas.

    • The requirements for the handling and disposal of bentonite slurries, construction effluent, sewerage and trade effluent should follow the Practice Note For Professional Persons: Construction Site Drainage, Professional Persons Consultative Committee, 1994 (ProPECC PN 1/94).

    • In order to monitor the disposal of C&D materials at public filling facilities and landfills, and control fly-tipping, a trip-ticket system shall be included in the tender document and implemented by the Environmental Team. Independent Checker (Environment) should be responsible for auditing the result of the system.

      1. Chemical Waste – The following mitigation measures shall be adopted to minimise chemical wastes:-

    • For those processes that generate chemical waste, it may be possible to find alternatives which generate reduced quantities or even no chemical waste, or less dangerous types of chemical waste.

    • Chemical wastes that is produced, as defined by Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation, should be handled in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical. Containers used for the storage of chemical wastes should:

    • be suitable for the substance they are holding, resistant to corrosion;

    • have a capacity of less than 450 litres unless the specifications have been approved by EPD; and

    • display a label in English and Chinese in accordance with instructions prescribed in Schedule 2 of the Regulation.

    • The chemical wastes will be segregated and stored in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal. An on-site temporary storage area should be provided .

    • The storage area for chemical wastes should:

    • be clearly labelled and used solely for the storage of chemical waste;

    • be enclosed on at least 3 sides;

    • have impermeable floor and bunding, of capacity to accommodate 110% of the volume of the largest container or 20% by volume of the chemical waste stored in that area, whichever is the greatest;

    • have adequate ventilation;

    • be covered to prevent rainfall entering (water collected within the bund must be tested and disposed of as chemical waste if necessary); and

    • be arranged so that incompatible materials are adequately separated.

    • Disposal of chemical waste should be:

    • via a licensed waste collector; and

    • to a facility licensed to receive chemical waste which offers a chemical waste collection service and can supply the necessary storage containers; or

    • to a reuser of the waste, under approval from EPD.

      1. General Refuse – The following mitigation measures shall be adopted to minimise general refuse:-

    • General refuse generated on-site should be stored in enclosed bins or compaction units separate from construction and chemical wastes. A reputable waste collector should be employed by the Contractor to remove general refuse from the site, separately from construction and chemical waste, on a daily or every second day basis to minimise odour, pest and litter impacts. The burning of refuse on-site is prohibited by law.

    • General refuse is generated largely by food service activities on site, so reusable rather than disposable dishware shall be used if feasible. Aluminum cans are often recovered from the waste stream by individual collectors if they are segregated or easily accessible, so separate, labelled bins for their deposit will be provided if feasible.

    • Office wastes can be reduced through recycling of paper if volumes are large enough to warrant collection. Participation in a local collection scheme should be considered if one is available.

Wastewater Management

      1. Construction effluent including, inter alia, sewage and trade effluent arising from construction phase of the site will be treated to comply with ProPECC PN 1/94 and the Technical Memorandum under Water Pollution Control Ordinance. Wastewater generated from all operational processes including bus washing and kitchen should be treated with interceptors before discharging into government sewers for ultimate disposal. An in-house treatment system with oil interceptors and grease traps and independent drainage system to storage tanks shall be provided within the depot. The treated effluent discharge will be complied with the limits stipulated in the Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters under Water Pollution Control Ordinance.

      2. In view of the close proximity of Chai Wan Cargo Handling Basin, no discharge of waste or wastewater will be made directly into the basin during both construction and operational phases. The operation of the depot shall be designed in order to minimise the production of wastewater. This will include the implementation of recycling or reuse of the treated wastewater for operation within the depot and other management and operation practices that could help minimise the wastewater at source.

      3. Adequate drainage, including peripheral channel around the site, should be provided for collection of drainage from the site. Adequately designed pretreatment facilities (e.g. oil interceptor, silt trap, etc) will be provided. The requirements of the soil and waste drainage system and that of the rain water drainage system are presented in the following:-

      4. Soil and Waste Drainage system – The soil and waste drainage system shall include:-

    • A one-pipe ventilated system will be installed for toilet drainage. Each water closet and urinal will be fitted with an anti-syphonage pipe. In general, drainage from all basins and pantry sinks (if any) will enter the system via a back-inlet gully. Anti-syphonage trap will be provided for each basin, sink and floor drain individually.

    • Anti-syphonage pipes will be branched off from the vent stacks & connected to water closets and urinals. Anti-syphonage pipes will be replaced by anti-syphonage traps for basins and floor drains.

    • Floor drains will be provided in carpark for drainage of waste water. Carpark waste water will be collected by a separate system and discharged to the foul water systems going through an oil/petrol interceptor.

    • Kitchen waste will be collected by drain outlets in kitchen and discharge to building foul water system after going through grease trap.

    • Soil and waste water will be discharged by gravity fall to the public sewers through terminal manholes via a series of underground or suspended manholes. Totally, there will be three terminal foul manholes required for the development.

    • Where the discharge levels will not be possible to connect into the external drainage, sump & pump pits will be provided to collect the soil & waste water before discharging into the external manholes via sewage pumps.

      1. Rain Water Drainage system – The rain water drainage system shall include:-

    • Rainwater outlets will be provided to open areas for rainwater drainage. These will be collected into down stacks inside services ducts or carpark and routed to terminal manholes via a series of underground pipes by gravity fall.

    • Rainwater outlets at areas subject to pedestrian or vehicular traffic will have flat grating. Domed grating outlets will be provided elsewhere throughout the development.

    • Rainwater will be discharged to the government stormwater drain through terminal manholes. Subject to the approval by the Government, three connections will be proposed to serve the development.

    • In order to comply with the regulation of Environmental Protection Department, a separate rainwater system shall be provided at R/F open carpark. All stormwater from R/F carpark shall be connected to an oil/petrol interceptor that would allow stormwater bypass during peak flow periods.

    • Separate water stacks will be provided by A/C contractor for A/C units condensate drain. The stack will be insulated to prevent surface condensation resulting from the low temperature of the condensate water. Condensate water will be discharged to join the rainwater drainage system at the lowest points as possible. A number of capped-off points will be provided at the rainwater drainage system at various points for connection of the condensate drain stack.

    • Similar to the soil & waste system, sump & pump pit will be provided for the rainwater drainage system when the discharge level will be impossible to connect into the external system. The discharge will be by means of the submersible sewage pumps.

Records of Wastes

      1. A recording system for the amount of wastes generated, recycled and disposal (including the disposal sites) shall be implemented.

        2. Training

      2. Training shall be provided to workers about the concepts of site cleanliness and appropriate waste management procedure. Encourage all site personnel to reduce, reuse and recycle wastes.

    1. Environmental Monitoring & Audit (EM&A) Requirements

      1. A stand-alone EM&A Manual has been developed to define the scope of the EM&A and EMS requirements for the construction and operation of the project to achieve satisfactory environmental performance. The above proposed mitigation measures have been incorporated in the EM&A and EMS documents.

       

       

       

       

    2. Summary and Conclusions

      1. The potential impacts of waste arising from the construction and operational phases of the proposed bus depot have been assessed. The wastes to be generated include excavated materials, C&D material, sewage, small volumes of chemical wastes, industrial wastes and general refuse. Waste management plan relating to good practice have been recommended to ensure that potential impacts are prevented and that opportunities for waste minimisation and recycling are followed.

      2. By implementing the waste management plan, the storage, handling, collection, transport and disposal of wastes arising from the construction and operation of the new depot should comply with regulatory requirements and no unacceptable environmental impacts should occur.

  2. land contamination

    1. Introduction

      1. A number of industrial installations, including vehicular repairing workshops, have been identified under the "Environmental Impact Assessment Ordinance" (EIAO) (Cap.499) and EPD’s "Practice Note for Professional Persons (ProPECC) PN 3/94: Contaminated Land Assessment and Remediation" as having potential for causing land contamination. To prevent land contamination problems the EIAO and the ProPECC note require the project proponents for the construction of major industrial installations which may give rise to land contamination to address the potential problems associated with their operations at the project planning stage.

      2. The primary aim of the land contamination component of this Study is to meet these requirements and to formulate appropriate measures for the prevention of potential contamination problems due to the operation of the bus depot.

      3. The specific objectives of the Land Contamination Study are clearly defined in Clause 3.3.4 of the Study Brief. The specific objectives are:

    • to identify possible sources of land contamination in the operational phase of the proposed bus depot; and

    • to formulate appropriate operational practices, waste management strategies and precautionary measures for prevention of contamination problems.

      1. The section presents the findings of the land contamination assessment and propose operational and waste management practices for prevention of contamination problems due to the operation of the bus depot.

    1. Legislation and Standards

      1. Assessments of land contamination sources and the potential impacts of particular development projects are investigated in accordance with EPD requirements as specified in the EIAO, its "Technical Memorandum on Environmental Impact Assessment Process" (EIA-TM), and ProPECC PN 3/94.

      2. Annex 19 of the EIAO-TM identifies a number of land use (eg car repairing workshops, the power plants, petrol stations, storage and scrap yards, and dumping grounds) as having the potential for land contamination, and provides guidance on a framework for development of a Contamination Assessment Plan (CAP) and a Remedial Action Plan (RAP) for investigation of these developments or activities with high land contamination potential.

      4. There are currently no standards for the cleanup of contaminated soil and groundwater in Hong Kong. In the absence of any specific criteria defined by the Hong Kong SAR Government, the Dutch Guideline Values presented in the ProPECC PN 3/94 guidance document will be used as a basis to evaluate the levels of contamination.

      5. The following legislation, EPD guidelines codes of practice are related to the management of wastes in Hong Kong and provide good waste management practices for prevention of land contamination problems:-

    • Waste Disposal Ordinance, in particular the Water Disposal (Chemical Waste) (General Regulation);

    • Water Pollution Control Ordinance, in particular Part III on prohibited discharges and deposits;

    • A Guide to the Chemical Waster Control Scheme;

    • A Guide to the Registration of Chemical Waster Producers;

    • Code of Practice on the Packaging, Labeling and Storage of Chemical Wastes;

    • Code of Practice on Handling, Transportation and Disposal of Polychlorinated Biphenyl (PCB) Waste;

    • Code of Practice on the Handling, Transportation and Disposal of Asbestos Waste; and

    • Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage System, Inland and Coastal Waters.

 

    1. Baseline Conditions

      2. Site Inspection

      1. A site inspection was conducted at the proposed site on 2 March 1999. The main objective of the survey was to establish the present use and relevant past land history in relation to possible land contamination. Special considerations were given to whether the existing operation had any potential contamination activities.

        2. Site History

      2. The site has been used as a temporary carpark for about 1 year. Prior to the carpark, the site formed part of the area of a temporary housing site.

        3.  

         

         

         

        Possible Impacts

      3. The inspection has revealed that only car parking activities at the site and no hazardous substances are employed. No "hot spots" were discovered relating to a land contamination by the visual inspection on site. Hence, land contamination is not envisaged.

    2. Potential Sources of Land Contamination

      1. Operation of the bus depot will require the use of a variety of chemicals and insignificant quantity of dangerous goods, and produce chemical wastes and sludge. If not properly managed, uncontrolled spillages and the handling and disposal of these materials have the potential to cause land contamination. The facilities which use, handle or store these materials may also be sources of land contamination. The chemicals to be used and the wastes to be generated at the bus depot are identified below.

        2. Potential Contamination Sources (from Chemical and Waste Inventories)

      2. The types and quantities of chemical to be used and wastes to be generated from the operation of the bus depot are given in Table 7.4.1.

        3. Table .1 Chemicals to be Used at the Bus Depot

        Facility

        Chemical

        Annual Consumption

        Quantity stored on-site

        Dangerous Goods /

        Paint

        NA

        100 litres

        Chemicals

        Thinner

        NA

        50 litres
         

        Turpentine

        NA

        50 litres
         

        Oxygen

        NA

        Insignificant
         

        Acetylene

        NA

        Insignificant
         

        Methyl Ethyl Ketone Peroxide

        NA

        Insignificant
         

        Acetone

        NA

        Insignificant
         

        Sulphuric Acid

        NA

        Insignificant

        Maintenance Area /

        Used engine oil

        100,000 litres

        6,600 litres

        Workshop

        Spent battery

        300 batteries

        50 batteries
         

        Waste lube oil

        20,000 litres

        1,400 litres
         

        Hydraulic fluids and waste fuel

        2,500 litres

        1,200 litres

        Diesel Fuel Storage Tank

        Diesel

        NA

        100,000 litres

        Note: [a] NA means data are not available

         

         

         

        Potential Contamination Sources (from Facilities)

      3. The following facilities will be the principle sources of land contamination during the operation of the bus depot:-

    • diesel fuel storage tank;

    • dangerous good store;

    • maintenance workshop; and

    • diesel fuel pipelines

      1. Leakage from the diesel fuel pipelines has the potential to cause land contamination. A final, detailed piping layout has yet to be determined, however, diesel fuel pipes will preferably be installed above ground. Should underground piping be required, it will be laid inside pipe trenches which will be lined concrete utility vaults / corridors to minimise the potential for land contamination. The trenches will have cover plates which will be easily removed to allow servicing or inspection. Any leakage of diesel fuel could therefore be detected during routine site inspections.

    2. Contamination Avoidance Plan

      1. The following section sets out the contamination avoidance plan that are recommended to prevent land contamination associated with contaminants arising from the construction and operation of the new depot.

        2. Prevention Measures for Diesel Fuel Spillage

      2. The procedures proposed in sections 7.5.3 to 7.5.16 are procedures and instructions for handling diesel fuel with respect to prevention of land contamination. Parallel measures will also be undertaken to protect the health and safety of depot personnel and to minimise water pollution in the event of diesel fuel spillage.

        3. Tank Construction

      3. It is proposed that diesel fuel will be stored in a below ground double skinned tanks situated within a concrete pit. It is proposed that leak detection equipment to monitor the interstitial space in the double skinned tank will be provided.

        4. Operation Procedures

      4. The tank will be fitted with a filling line with an isolating valve and non-return valve. A tank drain will also be provided. The filling and drain valves will be kept closed and locked, and the keys will be kept under the control of the engineer-in-charge.

      5. The diesel fuel storage tank will be inspected daily. The inspection will cover:-

    • verification of valve positions and security; and

    • tank level checks (i.e. the volume of diesel infilled, used and left in the tanks).

      1. Any leakage identified will be reported to the engineer-in-charge. The remaining diesel fuel in the leaking tank will immediately be transferred to appropriate containers. Daily inspection records of the tank will be kept in the site office.

      2. Tank integrity testing will be carried out on an annual basis by an independent qualified surveyor or structural engineer to ensure that the diesel fuel tanks are in good order.

        3.  

        Tank Filling Operation

      3. Filling will be undertaken by experienced staff of the fuel company under supervision of the operator. The procedures will be as follows:-

  • The diesel fuel storage tank will be checked to ensure that the filling valves are closed and locked.

  • On receipt of confirmation from the diesel fuel storage tank area, the transfer valve will be opened on the diesel fuel storage tank. The fluid level of the storage tank will be monitored.

  • The diesel fuel tanker filling valve will be opened to start filling.

  • The level will be noted when the storage tank high level is reached.

  • The filling valve on the diesel fuel tanker and the transfer valve on the storage tank will be closed and the tank level recorded.

Handling Oily Waste and Sludge from Oil/Petrol Interceptor

      1. Oil/Petrol interceptors will be inspected on a daily basis. If oily waste or sludge is found to accumulate inside the interceptor, it will be reported to the engineer-in-charge. The oily waste or sludge will be removed under supervision. The sludge recovered will be put into drums and labeled as chemical waste, which will be collected and delivered by a licensed operator to a licensed chemical waste treatment facility (e.g. the Chemical Waste Treatment Centre (CWTC) at Tsing Yi) for disposal. A record of cleaning and disposal of sludge will be kept.

        2. Training

      2. To ensure that appropriate actions are taken promptly in the event of diesel fuel spillage, and to prevent land contamination, training will be given to relevant staff so that they can respond effectively to the emergency situation. The training will cover:-

    • familiarisation with resources to combat diesel fuel spillage;

    • general methods to deal with diesel fuel spillage; and

    • procedures for emergency drills.

General Procedures

      1. Any spillage within the bus depot will be reported to the engineer-in-charge with the following details:-

    • location of spillage;

    • source and possible cause of spillage; and

    • extent of spillage.

      1. The engineer-in-charge will immediately tend to the spillage and initiate any appropriate health and safety and environmental actions to confine and clean up the spillage. The prime objectives in combating diesel fuel spill are:-

    • to identify and isolate the source of the spillage as soon as possible;

    • to contain the diesel fuel spillage and avoid infiltration into soil and discharge to sea;

    • to remove diesel fuel using absorbent materials;

    • to use dispersants to emulsify the diesel fuel, as required; and

    • to clean up the contaminated area using appropriate detergent.

Spillage During Tank Filling Operations

      1. Should spillage occur during filling of a storage tank, the filling procedures will immediately be stopped by closing the transfer and filling valves and the engineer-in-charge will be notified.

      2. Following inspection of the spillage, the engineer-in-charge will decide upon the best way to remove the spillage. Uncontaminated diesel will be recovered using a portable pump. Contaminated diesel not suitable for use as fuel will be removed using absorbent materials. The recovered material will then be put into drums, labeled as chemical waste and taken by a licensed collector to a licensed chemical waste treatment facility.

      3. If the spillage is to be removed via the oil (diesel) interceptor, this will be done in a controlled manner and staff will be posted at the spill and oil interceptor throughout the process. The flow of oil entering the interceptor will be controlled and monitored to ensure the satisfactory operation of the oil interceptor. When removal of the spillage is complete, the contaminated surface areas will be cleaned using suitable detergent.

        4. Diesel Fuel Spill Along the Pipelines

      4. In the event of a spillage along the diesel fuel pipelines, pumping should be stopped immediately and appropriate isolating valves closed. The spill product will then be removed using absorbent materials and put into appropriate drums, labeled as chemical waste, and then taken by a licensed collector to a licensed chemical waste treatment facility for disposal.

        5. Prevention Measures for Chemical Spillage

      5. The procedures proposed in sections 7.5.19 to 7.5.32 are procedures and instructions for handling chemicals with respect to prevention of land contamination. Parallel measures will also be undertaken to protect the health and safety of plant personnel and to minimise water pollution in the event of chemical spillage.

        6.  

        Storage of Chemicals and Chemical Wastes

      6. Chemicals or chemical wastes will only be stored in purpose-built storage areas. For chemicals which are classified as dangerous goods under the "Dangerous Goods Ordinance", all segregation, storage and handling will comply with the requirements of the "Code of Practice on the Packaging, Labeling and Storage of Chemical Waste".

      7. The same preventative approach as stated in Section 6.7.5 will apply to the storage of raw solid and liquid chemicals and chemical wastes.

        8. Emergency Procedures

      8. Any spillage will be reported to the engineer-in-charge who will attend to the spillage and initiate any immediate actions required to protect workers and to confine and clean up the spillage.

        9. Spillage/Leakage of Liquid Chemical/Waste at Storage Area

      9. Where the spillage/leakage is contained in the enclosed storage area, the material will be transferred back into suitable containers by appropriate equipment, such as hand-operated pumps, scoops or shovels. If the spillage/leakage quantity is small, it will be covered and mixed with suitable absorbing materials. The resultant slurry will be treated as chemical waste and transferred to suitable containers for disposal.

        10. Spillage/Leakage at Other Areas

      10. For spillage/leakage in other areas, immediate action will be taken to contain the spillage/leakage. Suitable absorbing materials will be used, as appropriate, to cover the spill. The resultant slurry will be treated as chemical waste and transferred in to containers for proper disposal.

      11. Areas that have been contaminated by chemical waste spillage/leakage will be decontaminated. For aqueous chemicals or wastes and water soluble organic waste, water will be used to clean the contaminated area. For organic chemical wastes that are not soluble in water, kerosene or turpentine will be used. The waste from the cleanup operation will be treated and disposal of as chemical waste.

        12. Recording of Incidents

      12. A detailed incident report will be compiled by the engineer-in-charge as soon as possible after any incident. The report will contain details of the incident, including an estimate of any amounts spilled, and any actions taken. The incident report will be used to evaluate any environmental impacts due to the spillage and to assess the effectiveness of the measures taken, so that improvements can be made to the response procedures for future incidents.

        13. Procedures for Disposal of Waste

      13. Used or expired chemicals, deteriorated synthetic lube oil, expired or non-usable paint and similar materials will be collected by a licensed collector and disposed of at a licensed chemical treatment facility. To avoid prolonged storage of chemical waste on site which may increase the potential for land contamination, waste will be removed from the depot on a regular basis.

    1. Environmental Monitoring & Audit (EM&A) Requirements

      1. A stand-alone EM&A Manual has been developed to define the scope of the EM&A and EMS requirements for the construction and operation of the project to achieve satisfactory environmental performance. The above proposed mitigation measures have been incorporated in the EM&A and EMS documents.

    2. Summary and Conclusions

      1. With proper implementation of the above practices and procedures, the potential for land contamination due to the operation the bus depot is expected to be minimal.

 

  2. Hazard ASSESSMENT

    1. Introduction

      2. Background

        1. The proposed development site for the New World First Bus Permanent Depot is located to the north of the Chai Wan Cargo Handling Area and to the north-east of the existing temporary servicing/parking site. The development is to provide bus parking, maintenance facilities and general office accommodation. A site location map is shown in Figure 1.1.

        2. The site selected in Chai Wan is zoned 'industrial' on the draft Chai Wan Outline Zoning Plan and the proposed usage is considered compatible with the adjoining developments. In the preliminary design, the site area is 11,900 sq. metres and the total GFA is about 60,000 sq. metres. The Bus Depot building is approximate 43 metres tall.

        3. A Quantitative Risk Assessment (QRA) for the proposed New World First Bus Permanent Depot is required to:

    1. determine the risks posed by the China Resources Company (CRC) oil terminal on the population of the development and whether such risks are within the limits set by the Government Risk Guidelines; and

    2. determine the risks on the surrounding population from the dangerous goods stored at the Bus Depot.

        1. The oil terminal is to the north-west of the development site and is about 100-metre away from the Bus Depot. The terminal is a Licensed Warehouse for the storage of hydrocarbon oil but is not designated as a Potentially Hazardous Installation.

          2. Objectives

        2. The scope of QRA covers the following:

    • to identify all hazards to the population of the proposed New World First Bus Permanent Depot in Chai Wan due to the storage, transport and handling of dangerous goods at the CRC Chai Wan Oil Terminal;

    • to identify all hazards to the surrounding population due to the transport, storage and handling of dangerous goods at the proposed New World First Bus Permanent Depot in Chai Wan;

    • to carry out a QRA of risks associated with the introduction of additional population at the Proposed Development and on-site diesel storage;

    • to compare individual and societal risks at the proposed development, and surrounding areas with the Hong Kong Risk Guidelines (HKPSG Chapter 11.4);

    • to identify and assess risk mitigation measures where applicable for the population at the proposed development and surrounding areas;

    • to report the findings of the QRA in a Hazard Assessment Report.

Structure of the Hazard Assessment

        1. An outline description of the proposed New World First Bus Permanent Depot is presented in Section 8.2 of this report, followed by a detailed description of the layout and operation of the CRC oil terminal in Section 8.3.

        2. The hazards to the population of the Bus Depot are then identified through a HAZOP study and review of past incidents (Section 8.4). The potential impact of these hazards is then analysed using computer models, as described in Section 8.5.

        3. Section 8.6 presents a risk assessment for the most significant hazards, i.e. those which could cause fatal injuries at the Bus Depot and Government building.

        4. Section 8.7 presents the results for the Base Case design, section 8.8 describes an analysis of mitigation measures and section 8.9 gives the conclusions of the analysis. Section 8.10 presents the recommendations.

    2. Proposed New World First Bus Permanent Depot

        1. The proposed development site of the New World First Bus Permanent Depot is located to the north of the Chai Wan Cargo Handling Area and to the north-east of the existing temporary servicing/parking site and is approximately 11,900m2 in area. The CRC oil terminal is situated on the east side of Chong Fu Road, north-west of the site.

        2. The internal layout of the building is not finalised yet and is subject to change. According to plans provided by LCP, see Appendix A, the building complex consists of 10 floors, including the roof, upper-ground and ground levels. Proposed areas on the upper-ground and ground floors include: workshops, re-fuelling and washing area, battery charging area and other maintenance work plants. Air-con workshop, electrical workshop, fibre glass workshop and maintenance offices will be located on the first floor. Buses and vehicles will be parked in the designated parking on 1/F, 2/F, 4/F, 6/F and the roof area. Other facilities located in the building include canteen & kitchen, staff recreational area, training rooms, function room and administration offices.

        3. There are three shifts working inside the Bus Depot: day (08:00-18:00), evening (18:00-02:00) and night (02:00-08:00). The maximum number of people present in the proposed depot building is shown in Table 8.2.1.

          4. Table .1 Maximum Number of People Present in the Proposed Bus Depot

          Time

          Works/Maintenance Area

          Office

          Day (08:00-18:00)

          320

          180

          Evening(18:00-02:00)

          140

          20

          Night(02:00-08:00)

          120

          5

           

        4. Currently in Shing Tai Road existing temporary servicing/parking site, there are 4 underground tanks for diesel storage, each of 22,500 l. It is proposed that 6 tanks will be placed underground of the New World First Bus Permanent Depot. About 72,000 l of diesel will be delivered on a daily basis by 4 road tankers and the safety features on the diesel pump and associated equipment will follow the US code (API RP 2005) [].

        5. Staff training on method of work, action on spillage, action on fire and method of deliveries will be provided for workers. First Bus is likely to invite specialist suppliers (i.e. Caltex, Shell etc.) to assist in training. Fire drill will be held every three months [].

    4. CRC Chai Wan Oil Terminal

      1. Overview of Terminal Facilities

        1. Information on the layout and the operation of CRC Chai Wan Oil Terminal was supplied by its Manager, Mr. C.T. Chong, in a meeting and a plant tour on 19th August 1998. Upon our request, further details were given by Mr. Chong in a telephone communication on 2nd Sept 1998. The above information was checked and confirmed by Mr. C.H. Ming of CRC on 9th August 1999.

        2. The oil terminal is a distribution centre for Liquefied Petroleum Gas (LPG), automotive diesel oil (ADO), industrial diesel oil (IDO) and kerosene for Hong Kong island. LPG cylinders are filled at Tsing Yi and transported by truck to the oil terminal. ADO, IDO and kerosene are transported in bulk by barges from Tsing Yi. These products are collected from the oil terminal by package trucks and road tankers.

        3. The storage facilities consist of one floating-roof storage tank of 500 m3, four cone-roof storage tanks of 1,000 m3 and a covered storage area for the LPG cylinders. The site adjoins a jetty on one side and is surrounded by 2.5m high fire walls on the other 3 sides.

        4. The layout plan of the oil terminal is shown in Figure 8.1.

      2. Plant Storage Facilities

        3. Tank Farm

        1. ADO and IDO are stored in the tank farm with 4 cone-roof tanks that are 10 m in diameter and 14 m in height. The storage capacities and Hong Kong Dangerous Goods (DG) classification for each fuel oil are listed in Table 8.3.1.

          2. Table .1 Storage capacities and Dangerous Goods Classification of Fuel Oils

          Fuel Oil Type

          Storage Tank Capacity, m3

          No. of Tanks

          Hong Kong Dangerous Goods Classification (UN Classification)

          ADO

          1000

          2

          Cat. 5 Class 3 (Class 3.4)

          IDO

          1000

          2

          Cat. 5 Class 3 (Class 3.4)

          kerosene

          500

          1

          Cat. 5 Class 2 (Class 3.3)

           

        2. The 1000 m3 tanks are surrounded by a 2m high bund and are equipped with a bottom-entry foam injection system and water sprays at the top which need to be started manually in case of fire. Other fire safety features will be covered in Section 8.3.4.

        3. Each tank is equipped with manual isolation valves on the bottom entry and exit connections.

          4. LPG Storage

        4. The maximum storage capacity for LPG in cylinders is 12 tonnes. The LPG cylinders are stored in cages outdoors under a canopy. Both empty and filled cylinders are stored under the same canopy. The cylinders are of various sizes: 10.5, 16 and 45 kg.

        5. The LPG storage area is equipped with a fixed water spray system and fire detection.

      3. Distribution of Products from the Oil Terminal

        4. Distribution of Fuel Oils

        1. Fuel oils are pumped from the storage tanks to the filling stations via dedicated pipework and pumps. The product pipelines run from the pump farm to the dye marker injection facilities and thence alongside the bund wall to a covered pipe trench, which connects to the filling stations.

        2. One station is for bulk filling (i.e. road tankers) and the other one is for packaged products. Both drums and tankers are used for IDO and kerosene while mainly tankers are used for ADO. The drum capacities are 200 litres for IDO and 18 litres for kerosene and the number of drums that are carried on each truck varies. Similarly, the amount of oil or kerosene transported in bulk varies. Caltex operates tankers which have a capacity of 16,000 litres. The frequency of truck visits at the filling stations is 60 each day, and the trucks park parallel to the filling stations for loading. After loading, the trucks leave the station and exit the terminal either by circling to the other side of the station or by reversing if the passage on the other side of the station is blocked.

        3. There are three filling positions at the drum filling station and four filling positions at the bulk filling station. Drum filling is undertaken by the truck driver and watched over by a CRC staff member, who will respond to any emergency. The truck driver is also responsible for the meter reading and the control of the pump during filling. At the drum filling station, the flow of products from the dispenser nozzle is controlled by the truck driver with a dead man's handle and the pumping rate is 1000 l/min. The diameter of the loading hose at the drum filling station is approximately 1 inch, whilst the diameter of the articulated arm used at the bulk filling station is 4 inches.

          4. Distribution of LPG

        4. The LPG cylinder loading operation is the reverse of the unloading operation described above. Fork lift trucks load the LPG cylinder crates onto trucks of varying capacity. Approximately 5 trucks, which may fluctuate depending on needs, are loaded each day between 9am and 4pm.

      4. Safety Features and Fire Fighting Facilities

        5. Tank Overfill Protection

        1. Each oil storage tank has a level detector which triggers a visual alarm in the control room when the oil level in the tank reaches the normal "fill" level. The control room is located at the ground floor of the office building.

          2. Spill Containment

          Jetty

        2. At the jetty, there is 4-inch kerbing on the ground surrounding the area where the hose from the barge is connected to the on-shore pipework. Immediately underneath the flanged connection, there is a tray to trap the dripping of oil during the connection/disconnection of the hose. Before the disconnection, the hose is lifted in the middle section using the jetty crane so that the oil in the hose can be drained via a drain line to a container kept at the jetty.

        3. Spills of oil onto the water can be contained by using floating booms kept near the jetty. If the amount of oil is large, it can be pumped from the water surface using a skimmer. If the amount is small, chemical dispersant is used.

          4. Filling Stations

        4. Spills at the filling stations are washed with buckets of water into the drainage channels which surround each filling station. The drainage channels are connected to an oil interceptor. Similarly, oil spills at other locations on the premises will flow into the drainage channels which completely surround the premises.

        5. The bund of the tank farm is designed to retain about 1200-1300 m3 of oil. If there is leakage in the pipework between the tank and the pump, the operator has to enter the bund area and manually shut the valve at the bottom of the tank.

          6.  

           

          Fire-Fighting Facilities

        6. Sea water for the water sprinklers protecting the LPG storage area, the filling stations and the tank farm is pumped by the 2 fire water pumps in the pump house, see Figure 8.1. One is an electrical pump and the other is fuelled by diesel oil. If the pumps in the pump house fail, a fire-fighting ship can be connected to the fire water main at four connection points along the sea wall near the pump house. There are also two hydrants for the fire engines near the main entrance of the oil terminal.

        7. The foam spraying network is a separate system from the water sprinkler network. The foam, supplied by a 3000 l foam tank, is manually supplied by opening the corresponding valve to a specific oil tank.

        8. Besides the water sprinkler, the LPG storage area is equipped with two 10 kg CO2 fire extinguishers at either end of the store. Two stocks of dry chemical for fire fighting, 150kg each, are stored close to the bund wall at two locations, one near the jetty and the other near the main entrance. Three other stocks of dry chemical, approximately 68kg each, are placed at the entrance and at 2 locations in the dye storage area.

        9. Water sprinkler systems are installed above the two filling stations and foam spray is also available near each station.

        10. The fire alarms in the oil terminal are directly linked to the fire station. If the main valve of the water sprinkler system of the oil tanks is opened, an alarm signal will also be sent to the fire station.

        11. The boundary wall of the premises is 150 mm thick, 2.5 m high, built of reinforced concrete and rated for 2 hr fire resistance.

      5. Surrounding Area

        1. On the north-west side of the oil terminal, there is a park and recreational open area (within 100 m of the terminal) stretching along the shore and farther away next to the park are Blocks 49 and 50 of Heng Fa Chuen (within 200 m of the terminal). Blocks 49 and 50 of Heng Fa Chuen are two adjoining 21-storey residential buildings with 8 living units on each floor of each building.

        2. Next to the south-east wall of the oil terminal, there is a motor vehicle scrap yard. The junk cars are piled up along the side of the wall of the terminal and a crane is used to move the cars on the site. Next to the scrap yard, and still within 100 m of the oil terminal is a sand depot where construction vehicles come to collect sand. Cranes are also operated on the site. Adjacent to the sand depot (within 200 m of the oil terminal) is an industrial building which is a logistics centre of the Government. The building is about 10 storeys high.

        3. The area opposites the oil terminal is used as a car park. On the day of survey (Wednesday 19 August 98) at about 5:30pm, there was little traffic on Chong Fu Road. There were, however, about 50 people, the majority children, in the park. Counts of people made for other areas are as follows:

          4. · scrap yard approximately 6

          · sand depot approximately 4

          · parking area approximately 5

        4. This assessment does not take into account possible use of the park by staff at the New World First Bus Depot during lunch hour or break periods.

    6. Hazard Identification

      1. Properties of Hazardous Products

        1. CRC Oil Terminal is involved in the receipt, storage and dispensing of diesel oils, kerosene and LPG. There will also be a large underground storage of diesel oils in the New World First Bus Permanent Depot.

          2. LPG

        2. The risk associated with LPG is considered to be insignificant (advised by EMSD); hence, LPG will not be included in the hazard assessment carried out later in the report.

          3. Diesel Oils

        3. Diesel oils are complex mixtures of middle distillate hydrocarbons in the C10 - C28 range of paraffinic, naphthenic, or aromatic types. Common additives include flow improvers (generally ethylene vinyl acetate co-polymers) or ignition improvers (generally octyl nitrates). The composition of IDO is similar to that of ADO, except it is higher in sulphur content and dyed. Typical physical properties are shown in Table 8.4.1a.

        4. Diesel oils are flammable materials with flash points well above ambient temperatures. Pool fires will form if the oil is released and ignited. Combustion produces carbon dioxide, carbon monoxide, nitrogen oxides, sulphur oxides and water vapour.

          5. Table 8.4.1a Physical Properties of a Typical Diesel Oil

          Property

          Value

          Molecular Weight

          125

          Liquid Density

          805 - 890 kg/m3 @ 150C

          Boiling Point

          160 - 3850C

          Vapour Pressure

          4 mbar @ 400C

          Flash Point

          55 - 700C

          Kerosene

        5. Kerosene is a flammable mixture of hydrocarbons produced by distillation of crude oil. It consists of hydrocarbons having carbon numbers predominantly in the range C9 through C16. Thermal decomposition can produce a variety of compounds, including carbon dioxide, nitrogen oxides and sulphur oxides. Incomplete combustion will generate thick black smoke and hazardous gases, including carbon monoxide.

        6. The typical physical properties of kerosene are listed in Table 8.4.1b.

        Table 8.4.1b Physical Properties of Kerosene

        Property

        Value

        Molecular Weight

        110

        Liquid Density

        780 kg/m3 @ 150C

        Boiling Point

        150 - 3000C

        Flash Point

        380C

      2. HAZOP Study

        1. The record of the Hazard and Operability (HAZOP) study of the CRC oil terminal is presented in Appendix Q.

        2. HAZOP is a widely used technique for identifying the hazards associated with a chemical or petrochemical facility in a systematic and structured manner. For this study a high level HAZOP study was undertaken using keywords to prompt identification of deviations from routine operation of the terminal which could cause injury or fatality at the New World First Bus Permanent Depot.

        3. The HAZOP considered the following aspects of the operation of the terminal:-

    • Fuel barge/berthing operation;

    • Bulk fuel storage;

    • Bulk tanker loading and export; and

    • Drum filling and export.

        1. The primary information available for the HAZOP study was the site layout plan, although a process flow diagram was also made available to the Consultants during the site visit.

        2. Table 8.4.2a below summarises the hazards in the CRC oil terminal identified during the HAZOP session.

 

Table 8.4.2a Summary of Hazards in CRC Oil Terminal Identified in HAZOP Study

Plant area/

operation

Hazardous Scenario

Cause

 

 

Ref

Description

 

 

Jetty

J1

Pool fire at jetty

Barge strikes berth

Fire/explosion on barge

Ranging (unloading hose detaches)

Hose connection/disconnection errors

Hose leak

Dropped object

Barge breaks away from berth

Leak from fixed pipework

Barge struck by another vessel

Lightning strike

 

 

J2

Explosion in fuel tank on barge

Local heating/ignition of flammable vapours

Tank farm

B1

Rim fire

Lightning strike

Burning embers from fire on adjacent site

Local heating/ignition of flammable vapour

 

 

B2

Bund fire

Spill from tank/tank connections

Lightning strike

 

 

B3

Fire outside bund

Spill followed by bund overtopping

Subsidence/earthquake/aircrash

 

 

B3

Explosion in tank

Heating/ignition of tank residues

Pump Farm/ Dye marker storage and injection

P1

Pool fire

Pump failure

Spontaneous tank/pipework failure

Overfilling of dye marker tank

External impact

Lightning strike

 

 

P2

Dye marker drums explode/rocket in fire

Flammable liquid spill/fire engulfing drums

 

 

P3

Explosion in covered pipe trench

Flammable liquid spill with local heating/ignition

Bulk Filling Station

F1

Pool fire

Spontaneous failure of pipework/fittings

Human error during tanker filling operation

Overfilling of tanker

Tanker struck by another vehicle

Vehicle fire

Lightning strike

 

 

F2

Explosion in tanker

Generation of aerosol/static discharge

Local heating/ignition of flammable vapour

Lightning strike

Drum filling station

D1

Pool fire

Damage to hose

External impact drum filling equipment

Human error during filling of drums

Dead mans handle jams open

Package truck impacted buy another vehicle

Vehicle fire

Lightning strike

 

 

D2

Product containers explode/rocket in fire possible leading to secondary fires

Spillage/fire at drum filling station

Vehicle fire

 

      1. Potential Hazards of Diesel Storage

        1. Potential hazards from the underground diesel storage, that could impact the staff working inside the Government Depot and other surrounding population, typically arise from a diesel spill with subsequent ignition.

        2. The only fixed population is in the Government Depot and other area of population will not be affected by any event at the Bus Depot. Other population, for example, people in scrap yard and passing vehicles have been considered, however, due to the very low number of people exposed and their ability to escape from the incident scene they have not been included in the risk calculation.

        3. Since diesel oil is not easily ignited, the affected area should be localised and confined. Nonetheless, the refuelling area is well segregated by drencher system and fire shutters which would prevent fire from spreading and smoke from escalating. However, it is still possible that the surrounding population, i.e. Joint Government Department Depot, could be affected by a spill external to the Bus Depot, i.e. while tanker unloading.

        4. The likely initiating/causal events for spills/fires are summarised in Table 8.4.3a [].

          5. Table 8.4.3a Summary of Hazards at New World First Bus Permanent Depot Identified

          Plant area/ operation

          Ref

          Scenario Description

          Causes

          Spill during vehicle refuelling

          FB1

          Pool fire

          Incorrect nozzle placement

          Hose rupture

          Hose leak

          Overfill

          Spill during tanker unloading

          FB2

          Pool fire

          Bad Connection

          Hose leak

          Hose rupture

          Early disconnection

          Driveaway

          Spontaneous tanker leak

          Tanker truck collision

          Spill from storage

          FB3

          Groundwater contamination/ possible fire in remote location

          Corrosion of tanks

          Incorrect material of construction

          Wear out

          Accidental damage

          Vehicle fires and accidents

          FB4

          Pool fire

          Spontaneous vehicle fire

          Spontaneous tanker fire

          Vehicle crash

          Vehicle impact with pump

          Vehicle impact with filling point

          Spill During Vehicle Refuelling, FB1

        5. During the refuelling process, diesel spills can occur if:-

    • the nozzle is not correctly inserted into the vehicle fuel tank before fuel flow is started;

    • the supply hose from the pump leaks or ruptures during fuel flow;

    • the vehicle is driven away during filling; or,

    • the fuel tank may be overfilled.

        1. The last incident is usually prevented or limited to very small spills if the pump systems have pressure sensitive automatic cut-offs. The result of other types of incidents is a fuel spill, although in all cases, the spill will usually be rapidly isolated as the pump can easily be switched off. Any spill of fuel, however, can result in a pool fire if an ignition source is present and may potentially escalate to the vehicle or equipment (e.g. paper towels, rubbish bins).

          2. Spill During Tanker Unloading, FB2

        2. Tank filling is potentially the most hazardous operation. The tanker arrives carrying about 18,000 l of diesel oils (assuming 5 x 3,600 l/compartment) and must manoeuvre to the correct position for filling the tanks. Manual procedures are required to connect the supply hose to the filling point. The potential exists for various incidents to occur during delivery. Since the hose connection is a manual procedure, there is the possibility of a poor connection leaking or disconnecting completely during fuel delivery. Besides, the fuel supply hose may leak or rupture during the fuel delivery, or the driver may attempt to drive the tanker away without realising that the delivery hoses are still connected. Finally, the driver may attempt to disconnect the hose prematurely while diesel is still being delivered. All these scenarios may cause a spill at the tank filling point that could result in a pool fire around the tanker if ignited. However, tankers are fitted with a manual push button shut-off valve that will stop fuel flow to the storage tanks when activated. The possibility of overfill via the tank vent can be prevented by ensuring that the vent on the vapour return manifold is higher than the liquid level in the tanker (typically 3.5 metres). Alternatively, overfill limit the amount of diesel released in the event of a spill during tanker unloading. A related incident is that the tanker may have a spontaneous leak from one of its compartments due to corrosion, leaking gaskets, etc.

        3. A tanker truck collision may happen when a tanker enters or leaves the Bus Depot and could result in a spillage of flammable liquid. A fire may result which may affect the large populations of the Government Depot. A spillage resulting in this consequence, however, is unlikely because the tankers will be travelling at low speeds, have a degree of impact protection implicit in their design and are driven by trained personnel.

          4. Spill from Storage, FB3

        4. Diesel leaks from the underground tanks or pipework systems may seep into the ground and enter chambers such as tunnels, drains and sewers. The undetected build-up of diesel in a confined space creates a fire hazard. However, the concrete casing of the tanks would be expected to protect against diesel seepage to the surrounding soil.

        5. It is anticipated that leakage from the storage tanks will be detected by monitoring devices installed on the tanks and inventory checks are conducted by New World First Bus. Furthermore, leakage due to tank corrosion or material failure should be revealed during hydraulic tests conducted every 2 to 5 years. The potential for leakage is therefore expected to be low.

          6. Vehicle Fires and Accidents, FB4

        6. Spontaneous vehicle fires are known to occur occasionally. Generally, these involve vehicles that come to a stop after travelling long distances in hot weather. When the vehicle is parked, the engine cooling system of the vehicle shuts down and the temperature of the engine consequently rises for a short period of time. It is during this time that vehicle engines may spontaneously ignite. Vehicle fires may also be caused by other reasons such as tyre fire and electrical fault.

        7. In addition to vehicle fires, accidents involving vehicles may also occur. Given the low speed nature of the incidents, it is considered that a vehicle incident generating diesel spills is extremely unlikely and is therefore not being considered in this study.

      1. Review of Past Incidents

        1. A review of past incidents (world-wide) was undertaken to provide further background information on the sorts of incidents which could be expected to arise at the oil terminal.

        2. Information on past incidents was obtained from the MHIDAS database, which is one of the most comprehensive collections of data available on incidents at major hazard plant world-wide. Various searches of the database were made covering aspects such as incidents involving kerosene or diesel oils and incidents involving atmospheric storage tanks, road tankers or drums.

        3. The MHIDAS records are presented in Appendix R. Some important observations of the historical data are as follows:

Atmospheric Storage of Diesels Oils and Kerosene

    • Lightning emerges as a significant cause of fires on diesel tanks and poorly-controlled tank clean-out operations have also led to worldwide fire/explosion events.

Drums

    • There is evidence of drums rocketing when engulfed in fire.

Road tankers/Barges

    • There is evidence of explosions occurring within kerosene road tankers or barges, but this has been a result of previously carrying loads of lower flash point gasoline.

        1. Two recent relevant incidents in Hong Kong were the flooding of Concorde Road in the oil spillage from Kai Tak tank farm and a fire in 1997 caused by lightning strike during a tanker off-loading at Mobil Tsing Yi Terminal.

    1. Consequence Modelling

      1. Introduction

        1. This section of report presents the methodology and the results of modelling the hazardous impacts of various accident scenarios at the oil terminal upon the occupants of the New World First Bus Permanent Depot and possible accidents due to the underground diesel storage in the Bus Depot.

        2. These scenarios have been identified in the HAZOP exercise and the review on past incidents. The hazardous impacts evaluated include thermal radiation from fire and overpressure from explosion. For hazardous releases, vapour cloud dispersion is analysed to determine the cloud concentration at the Bus Depot. The fatality rate is estimated from probit functions which provide relationships between a dose effect and the level of fatality.

      2. Methodology

        1. A number of widely-used and well-validated computer consequence models were employed in this study. These models cover the following hazardous phenomena:

          2. · Pool fire

          · Pool spread / dense gas dispersion

          · Thermal radiation impact

          Hydrocarbon Pool Fires Model (Society of Fire Protection Engineers)

        2. This program simulates the behaviour of a burning pool of flammable liquid by estimating key flame geometry parameters and by calculating the resultant levels of thermal radiation incident upon various downwind locations of observer. Pool fires on water, pool fires on land (or on top of tanks) and trench fires on land can be analysed, either confined or unconfined.

        3. Details on the program are found in the User's Manual for Hydrocarbon Pool and Trench Fire Thermal Radiation Computer Programs [].

        4. The dimensions of the pool fire input to the model for different scenarios are shown in Table 8.5.2a.

          5.  

           

          Table 8.5.2a Pool Fire Dimensions

          Ref

          Site

          Location

          Dimensions

          Notes

          F1

          D1

          CRC

          Filling station

          15.2mx6.8m

          Dimensions of area enclosed by drainage channels at filling station

          B1*

          B2

          CRC

          Bund

          25mx25m

          Dimensions of tank farm bund

          B3

          P1

          CRC

          Outside bunded area

          54mx41m

          Dimensions of CRC site

          FB1

          NWFB

          Re-filling area

          42mx29.4m

          Dimensions of area enclosed by drainage channels on ground floor

          FB2

          NWFB

          Road

          19mx19m

          Dimensions of the pool fire, cannot extend the distance between drains and road width.

          * worst cases used.

          Pool Fire from Tanker Unloading

        5. The radiation from a pool fire caused by a tanker spill has been modelled using Shell Research Model []. It has been calculated that the size of the pool fire should not exceed 19 m in diameter in the worse case. There are drains on the sides of road and the width of the road will confine the size of spillage area, hence, it should be limited to about 15 m in any direction.

          6. Smoke Ingress

        6. Smoke ingress of CO and CO2 to the surrounding population, i.e. Joint Government Department Depot, has been modelled using Gaussian dispersion []. The smoke production rate is a function of the pool fire diameter. Calculations give outdoor and indoor concentrations of CO and CO2 at 20 m away from the point source, fire located at the Bus Depot (see Appendix S for smoke ingress assessment).

          7. Pool Evaporation and Dispersion Models of HGSYSTEM 3.0

        7. The HGSYSTEM package is a set of atmospheric dispersion models developed by Shell Research Ltd. It contains a wide range of modules to simulate source terms, near-field and far-field dispersion for HF and other pollutant releases. It has been assessed against other models and found to rank amongst the best available atmospheric dispersion models in the world.

        8. HGSYSTEM can be used to study one particular aspect of a dispersion situation, using one of the available HGSYSTEM models. But by using several modules in sequence, HGSYSTEM can also be used to simulate a complete scenario starting from a release source, then modelling the near-field dispersion and finally calculate the far-field dispersion.

        9. Detailed information on the models used in HGSYSTEM 3.0 can be found in the Technical Reference Manual (Post, 1994).

          10. Thermal Radiation Probit Function

        10. The widely used probit function for fatality from thermal radiation was derived by Eisenberg et al []:

          11. Pr = -14.9 + 2.56 ln(Q t4/3)

          where Q = radiation intensity, kW m-2

          t = exposure time, s

        11. The probit value that corresponds to 1% fatality is 2.67. The thermal dose (i.e. Q t4/3) that gives this probit value of 2.67 is 957 kW m-2 s4/3.

        12. People can escape injury from thermal radiation by shielding themselves. For people indoors or near to buildings, the time needed to react and move to a shield is estimated to be less than 20 seconds. According to the probit function and the assumed escape time of 20 s, the thermal radiation intensity has to be about 18 kW m-2 to cause 1% fatality in an exposed population.

        13. Based on the above analysis and the thermal radiation calculated by different computer models, the fatality rate can be predicted for different scenarios or failure cases.

      3. Consequence Modelling Results

        1. The analysis has been undertaken to determine which of the various accident scenarios identified in the HAZOP study could cause fatal injury amongst people at the New World First Bus Permanent Depot.

        2. The results of the consequence modelling are presented in Table 8.5.3a and b. The analysis focuses on the hazards and injury caused to people in the Bus Depot and its surrounding population.

        3. Kerosene was used in the modelling of pool fires. It has been confirmed by additional computer runs that diesel will give a hazard range similar in magnitude to that of kerosene.

Table 8.5.3a Consequence Modelling Results from CRC Oil Terminal

Ref

Scenario

Hazardous Effects

Relevant

Threshold Value

 

Hazard

Range (m)

 

Approximate Distance to Bus

Depot (m)

 

Significant

hazard to Bus Depot?

Notes

J1

Pool fire at jetty

Thermal radiation

-

-

-

N

1. See pool fire modelling for hydrocarbon releases at terminal (Scenarios B1-3), which represent a more onerous case for the Bus Depot.

 

 

 

 

Smoke ingress into Bus Depot

-

-

-

N

1. As above

J2

Explosion in fuel tank on barge

Thermal radiation from pool fire

-

-

-

N

1. Not considered likely to have any significant impact on Depot, as jetty is 100 metres from building, shielded by tank farm.

 

 

 

 

Blast/projectiles

-

-

-

N

1. As above

B1

Fire on cone roof tank

Thermal radiation

-

-

-

N

1. See pool fire calculations for Scenario B2 (fire in bund)

 

 

 

 

Smoke ingress into Bus Depot

800 ppm (CO)

11.4% (CO2)

for X minutes

-

-

Y

1. Calculations of smoke ingress presented in Appendix S.

2. Calculations assume smoke is not significantly diluted in atmosphere, ie contains 800 ppm CO and 11.4% CO2.

3.Calculations do not take account of impaired visibility, smoke temperature, other toxic combustion products or oxygen depletion.

B2

Fire in bund

Thermal radiation

4 kW m-2

(pain threshold)

53

100

N

1. SFPE pool fire model

2. Direct exposure to this radiation level will cause pain []. However no injury is predicted for people indoor or able to find a shelter within 20s of exposure. Clothing and building material reduce exposure.

 

 

 

 

 

 

18 kW m-2

(1% fatality)

 

16

100

N

1. Eisenberg probit for 1% fatality for 20s exposure

 

 

 

 

Smoke ingress into Bus Depot

-

-

-

Y

1. As above for tank fire

B3

Pool fire with overtopping of bund

Thermal radiation

-

-

-

N

1. Large hydrocarbon pool fire outside bunded area assessed for Scenario P1 below

 

 

 

 

Smoke ingress into Bus Depot

-

-

-

Y

1. As above for tank fire

B4

Explosion in tank

Blast

-

-

-

N

1. Explosion occurring during tank clean-out not considered likely to give significant blast effects at Bus Depot.

 

 

 

 

Thermal radiation (from pool fire)

-

-

-

N

1. Covered by Scenarios B2 and B3 above.

P1

Catastrophic failure of pump leading to pool fire outside bunded area (instantaneous 1000m3 release of kerosene)

Pool fire

18 kW m-2

(1% fatality)

20

75

N

1. Predicted flame length is 55m. With wind blowing at 3m/s toward the Bus Depot, the tilt of flame is 300 from vertical. Under this condition, the top of flame is not close to the Depot.

P2

Dye marker drums rocket/explode in fire

Projectile hazard/

secondary fires

-

-

-

N

1. Past incidents show evidence of drums rocketing when engulfed by fire. However, the Bus Depot is too far to be affected.

P3

Explosion in covered pipe trench

Projectile hazard

-

-

-

N

1. Not considered a significant hazard as explosion of flammable vapour inside trench at or near LFL concentration will not generate significant blast.

F1

Pool fire at bulk filling station (continuous release of kerosene, 1000L/min, confined within area surrounded by drainage channels)

Thermal radiation

4 kW m-2

(pain threshold)

34

85

N

1. SFPE pool fire model

2. Direct exposure to this radiation level will cause pain []. However no injury is predicted for people indoor or able to find a shelter within 20s of exposure. Clothing and building material reduce exposure.

 

 

 

 

 

 

18 kW m-2

(1% fatality)

18

85

N

1. Eisenberg probit for 1% fatality for 20s exposure

 

 

 

 

Smoke ingress into Bus Depot

-

-

-

Y

1. As above for tank fire

F2

Explosion in tanker

Blast/projectile hazard

-

-

-

N

1. Not considered a significant hazard assuming tankers are not used for delivery of gasoline as well.

D1

Pool fire at drum filling station

Thermal radiation

-

-

-

N

1. See pool fire modelling for Scenario F1 above.

 

 

 

 

Smoke ingress into Bus Depot

-

-

-

Y

1. As above for tank fire

D2

Product containers explode/rocket in fire

Projectile hazard/

secondary fires

-

-

-

N

1. Past incidents show evidence of drums rocketing when engulfed by fire. However, the Bus Depot is too far to be affected

 

Table 8.5.3b Consequence Modelling Results of Diesel Storage

Ref

Scenario

Hazardous Effects

Relevant

Threshold Value

 

Hazard

Range (m)

 

ApproximateDistance to Gov’t

Depot (m)

 

Significant

hazard to Gov’t Depot?

 

Notes

FB1

Spill during vehicle refuelling

Pool fire

-

-

-

Y

Small fire, not likely to have significant impact on Gov’t Depot.

 

 

 

 

Smoke ingress at Gov’t Depot

-

-

-

N

Smoke will be localised at the refuelling area of the Bus Depot.

FB2

Spill during tanker unloading

Thermal radiation

18 kW m-2

(1% fatality)

23

20

Y
  1. Frequency and severity depends on spill size.
  2. Predicted flame length is 26m. With wind blowing at 3m/s toward Gov’t Depot.

 

 

 

 

Smoke ingress at Gov’t Depot

10.9 ppm (CO)

0.18% (CO2) for 2 hours

-

20m

N
  1. Calculation of smoke ingress presented in Appendix S.
  2. Calculations do not take account of impaired visibility, smoke temperature, other toxic combustion products or oxygen depletion.

FB3

Spill from storage tanks

Groundwater contamination / possible fire in remote location

-

-

-

N

Underground leak could spread over a large area if it enters into sewers.

FB4

Vehicle fires and accident

Pool fire

-

-

-

N

Fire is not likely.

        1. The following summarises the results of the consequence modelling for hazardous events:

CRC Oil Terminal

    • Fatal injury is not predicted for people at the Bus Depot from exposure to thermal radiation from pool fires at the oil terminal.

    • Major fires at the oil terminal might cause smoke ingress into the Bus Depot; however, due to the large distance between the oil terminal and the Bus Depot, it is likely that there will be no significant effect.

    • A major fire engulfing drums of flammable liquid at the oil terminal could lead to a projectile hazard and secondary fires at the Bus Depot. However, due to the large distance between the oil terminal and the Bus Depot, it is likely that there will be no significant effect.

    • The predicted flame length of a pool fire at the oil terminal is 55m. With wind blowing at 3m/s toward the Bus Depot and a tilt of flame 30o from vertical, the top of the flame is not close to the Bus Depot which is about 100m away from the oil terminal. Hence, the Bus Depot is not likely to be directly impinged upon by the flame.

New World First Bus Depot

    • The major hazards from diesel storage in the Bus Depot are spill during vehicle refuelling and spill during tanker unloading. Small fire is expected but is unlikely to have significant impact on the Gov’t Depot and the surrounding population. Other hazards are not considered to be significant.

    2. Risk Assessment

      1. Introduction

        1. Section 8.4 of the report identified various accident scenarios which could lead to fatal injury to people working at the New World First Bus Permanent Depot. This section of the report assesses the risk to these people by considering the likelihood of such events occurring.

        2. From Section 8.5 the events identified as presenting a significant hazard to staff at the New World First Bus Permanent Deport are as follows:

          3. Table 8.6.1a Summary of Significant Hazards to New World First Bus Permanent Depot

          Plant area

          Scenario Ref

          Description

          Most significant effects

          Tank farm

          B1

          Rim fire on cone roof tank

          Smoke ingress into Bus Depot, exposure of occupants to toxic combustion products (CO/CO2)
           

          B2

          Fire in bund

          As above for B1
           

          B3

          Pool fire with overtopping of bund

          As above for B1

          Fire escalates to Bus Depot

          Rocketing of drums

          Pump farm/ Dye storage

          P1

          Pool fire

          As above for B1

          Fire escalates to Bus Depot

          Rocketing of drums/LPG cylinders

          Bulk filling station

          F1

          Pool fire

          As above for B1

          Drum filling station

          D1

          Pool fire

          As above for B1

          Refuelling area

          FB1

          Pool fire

          As above for B1

          Unloading zone

          FB2

          Pool fire

          Smoke ingress into Gov’t Depot, exposure of occupants to toxic combustion products (CO/CO2)

          Possible fire effects

           

           

          Scenarios B1-3, P1, F1 and D1: Major fires at the oil terminal

        3. For scenarios B1-3, P1, F1 and D1 there is a hazard of smoke ingress into the Bus Depot. Additionally, for scenarios B3 and P1, in which the pool fire may involve large quantities of flammable liquid. There is the risk of fire spreading across the entire site and possibly onto Chong Fu Road.

        4. With regard to the hazard of smoke ingress into the Bus Depot, the severity of the hazard will depend on a number of factors, including:

    • the size and duration of the fire;

    • the degree of confinement of the fire;

    • the toxic composition of the smoke;

    • the extent of dilution of the smoke in the atmosphere;

    • the air flow pattern around the building (including the influence of the fire itself);

    • the location of the building air intakes; and

    • the ventilation air change rate of the building.

        1. Calculations undertaken in Section 5 show that, in the absence of any significant dilution of smoke in the atmosphere, intolerable conditions could arise in the building within about 5 minutes. This calculation is based on the criteria applied to Temporary Refuges on offshore installations and represents the time in which a person would be expected to become incapacitated due to the combined effects of CO2 (causing hyperventilation) and CO (toxic narcosis).

        2. This calculation considers only the toxic impact of smoke (CO and CO2 components), however other significant factors are:

    • reduced visibility, impairing escape and prolonging exposure to the toxic components of the smoke (the smoke emanating from the fire would appear opaque to the human eye);

    • the smoke temperature (temperatures of around 70-80 oC, one tenth of that at the source, would be intolerable for more than about 10 seconds);

    • the presence of other toxic components (NOx, SOx etc); and

    • oxygen depletion (sudden depletion of the oxygen concentration to less than 14% may lead to loss of consciousness within about 1 minute).

        1. Although the smoke ingress problem at the Bus Depot should not be significant, an analysis on smoke ingress has been carried out. In view of the hazard associated with smoke ingress into the Bus Depot, further attention will be given to improve fire fighting facilities in the Bus Depot, and incorporate suitable protection measures in the design of the building. The risk assessment focuses on Scenarios B1-3, P1, F1, FB1 and FB2, the major fire scenarios. Fires at the drum filling station (Scenario D1) are likely to be mostly minor in nature and have therefore not been considered further.

        2. A detailed analysis of smoke ingress has been carried out using Gaussian dispersion modelling[]. The smoke production rate is a function of the pool diameter which is taken to be the diameter of the 1000 m3 cone roof tank, the largest tank in the terminal. The mass burning rate is calculated using correlation provided by Babrasukas [] and calculations show that the concentrations of CO and CO2 at a 100 m away from the point source are 1.2 ppm and 0.02% respectively and the indoor concentrations are even lower (refer to Appendix S). Hence, there would not be a significant impact to the Bus Depot, which is a long distance away from the CRC terminal and results in a substantial reduction of the toxic products at the Bus Depot.

      1. Frequency Estimation

        2. Scenarios B1-3, P1 and F1: Major fires at the oil terminal

        1. The frequency of major fires at the oil terminal have been estimated as shown in Table 8.6.2a below:

          2. Table 8.6.2a Frequency Estimation for Scenarios B1-3, P1 and F1: Major fires at the oil terminal

          Scenario

          Ref Description

          Fire Frequency

          Notes

          B1

          Fire on cone roof tank

          1.1x10-4 per tank-year

          Based on Lees [vii], in turn based on historical data for fires in fixed roof storage tanks over a period of 20 years. Other data in Lees [vii] from the American Petroleum Institute suggests no significant difference between the incidence of cone roof tank fires versus fixed roof tank fires.

          The frequency from Lees [viii] is reduced by a factor of 10, noting the presence of the foam injection system on the tanks at the CRC terminal (not a normal feature of diesel/kerosene storage tanks).

          B2

          Fire in bund

          1.2x10-5 per tank-year

          Based on Davies, et al [] for fires of flammable liquids in bunds.

          B3

          Pool fire with overtopping of bund

          1.2x10-6 per tank-year

          10% of bund fires are assumed to result in significant overtopping of the bund.

          P1

          Pump farm: pool fire

          6.0x10-6

          per year

          Pump catastrophic failure frequency of 7.8x10-8 per hour (E & P Forum, 1992) in service multiplied by 5 hours service per day (300 days per year). An ignition probability of 0.05 is assumed.

          F1

          Bulk filling station: pool fire

          3.0x10-4

          per year

          Based on 6000 bulk tanker filling operations per year and human error probabilities of 10-3 (initial error, eg loading arm not correctly inserted before prior to starting pump) and 10-2 (failure to recover, eg by stopping pump). An ignition probability of 0.005 is assumed.

           

          Scenarios FB1 and FB2: Major fires at the New World First Bus Depot

        2. The frequency of spills due to tanker unloading is estimated based on historical data of petrol filling stations (PFSs). It is a conservative estimate because petrol is more flammable than diesel oils. Both Hong Kong data and UK data are used.

        3. There are approximately 181 PFSs currently operating in Hong Kong. In the 4 year period between 1995 and 1998 that incident records at PFSs in Hong Kong have been maintained (equivalent to 724 PFS operating years), no incidents of spill at PFSs have been reported in Hong Kong. Assuming there is at least one delivery per day at each PFS, the total number of deliveries during this period is 264,260.

        4. When failure are relatively rare and distributed over time, the assumption is usually made that the failures will obey a Poisson distribution in the time interval while the intervals between events will follow an exponential distribution. The Poisson distribution is represented as:

          5. p(x) = l x e-l / x!

          where x is a discrete random variable,

          p(x) is a the probability function of x and

          l is a positive constant

        5. In the case of ‘zero’ failures, x = 0 and p(x) = e-l

        6. For zero failures, the failure rates corresponding to various confidence levels can be estimated. The estimate at the 50% confidence level corresponds to there being an equal chance of getting either 0 or more than 0 failures, i.e. that there is a 50% probability of getting 0 failures, in which case:

          7. l = ln(1/p(x)) = ln(1/0.5) = 0.7

        7. Similarly, the estimate for 95% confidence level is:

          8. l = ln(1/0.05) = 3.0

        8. The frequency of spills can be derived from the above data assuming 3.0 spills (95% confidence level) in 264,260 deliveries. This gives a frequency of 1.1 x 10-5 per delivery.

        9. There is very little published information or data sources otherwise, on spills or fires in PFSs. The only published data relates to spills and fires during tanker unloading, as estimated in the ACDC study []; it is given in Table 8.6.2b.

          10. Table 8.6.2b UK Petrol Spills - Historical Data

          Spill Quantity (litre)

          Spill Likelihood per delivery

          Ignition Probability

          (Petrol)

          Ignition Probability (diesel)*

          20-200

          1.1 x 10-5

          0.01

          0.001

          >200

          5.5 x 10-6

          0.03

          0.003

          *Ignition probability of diesel is taken to be one-tenth of that of petrol because petrol is a lot more flammable than diesel.

        10. The above data are based on one large spill and two small spills recorded in two years. The number of deliveries in this period is about 181,818. As compared to the Hong Kong data, the UK data predicts a slightly higher frequency of spill. It is proposed to adopt the UK data as a conservative estimate.

        11. The above data indicates that the majority of spills involving tankers are of the order of tens or few hundred litres in size. For the purpose of this analysis, three spill sizes have been chosen to represent the range of spills that could occur during tanker unloading:

    • small spills of the order of 200 l;

    • medium spills, which are represented by a 1,000 l spill (it should be noted that spills exceeding 200 l are regarded as large spills in the ACDS study); and

    • large spills that are equivalent to the release of one compartment (taken to be 3,600 l) of a tanker.

        1. Diesel is delivered daily by road tankers. Based on the data of Table 8.6.2b, the frequencies of small and medium spills was estimated to be 4 x 10-3 and 2 x 10-3 per year respectively.

        2. There is no data on the frequency of large spills such as those involving one tanker compartment volume within a filling station. However, large spills have occurred during transport due to causes such as overturning. In this connection, it may be noted that two major incidents of tanker spills have occurred on Hong Kong roads in the last few months due to tanker overturning. Fortunately, the spills did not ignite although they did spread over a large area.

        3. There is no sufficient data to estimate the frequency of large spills. It is therefore assumed that the frequency of a large spill is an order of magnitude lower than the frequency of medium spills, that is 5.5 x 10-7 per delivery (i.e. 2 x 10-4 per year).

        4. The frequencies of spills used in this study are summarised in Table 8.6.2c.

          5. Table 8.6.2c Frequencies of Spills

          Spill Size

          Volume (l)

          Spill Frequency (per delivery)

          Proportion

          Small

          200

          1.1 x 10-5

          65 %

          Medium

          1,000

          5.5 x 10-6

          32 %

          Large

          3,600

          5.5 x 10-7

          3 %

          All Spills

          		  

          1.7 x 10-5

          		  

           

        5. The overall spill frequency per delivery based on the above matches broadly with the value derived from the Hong Kong data corresponding to the 90 % confidence level.

        6. Ignition probabilities from the ACDS Study, based on historical data and UK fire Brigade experience, shown in Table 8.6.2b. To account for the large number of electrical fires in Hong Kong PFSs (12 incidents in the last 4 years), a higher ignition probability of 0.002 is considered for small spills, 0.005 for medium spills and 0.01 for large spills (large spills have a greater likelihood of ignition). Based on the above, the frequency of fire is estimated in Table 8.6.2d.

          7. Table 8.6.2d Frequencies of Hazardous Event Outcomes for FB2

          Ref

          Initiating Event

          Spill Frequency per delivery

          Delivery per year

          Spill Frequency per year

          Ignition Probability

          Fire Incidents Frequency (per year)

          FB2

          Spill during tanker unloading

          		          
           

          -small

          1.1 x 10-5

          365 x 4

          1.6 x 10-2

          0.002

          3.2 x 10-5
           

          -medium

          5.5 x 10-6

          365 x 4

          8.0 x 10-3

          0.005

          4.0 x 10-5
           

          -large

          5.5 x 10-7

          365 x 4

          8.0 x 10-4

          0.01

          8.0 x 10-6

        7. Spill during vehicle refuelling may happen because of incorrect nozzle placement, hose leakage, hose rupture or overfilling. Assuming the vehicle refuelling staff are as well trained as the tanker driver, 1.1 x 10-5 is used as the spill frequency per delivery, which is then multiplied by 100 (assumed that one out of 2-3 buses are refuelled per day) and 365 days to give a spill frequency of 0.4. The ignition probability of 0.001 is considered for this small scale spill. The frequency of fire is shown as below:

          8. Table 8.6.2e Frequency of Hazardous Event Outcome for FB1

          Ref

          Initiating Event

          Spill Frequency per delivery

          Delivery per year

          Spill Frequency per year

          Ignition Probability

          Fire Incidents Frequency (per year)

          FB1

          Spill during vehicle refuelling

          1.1 x 10-5

          365 x 100

          0.40

          0.001

          4.0 x 10-4

           

        8. The frequencies of major fires at the Bus Depot have been estimated as shown in Table 8.6.2f below:

          9. Table 8.6.2f Frequency Estimation for Scenarios FB1 and FB2: Major fires at the NWFB Depot

          Scenario

          Ref

           

          Description

          Fire Frequency

          FB1

          Pool fire due to spill during vehicle refuelling

          4.0 x 10-4

          FB2

          Pool fire due to spill during tanker unloading

          8.0 x 10-5

           

        9. The transportation risk of diesel by tanker is to be assessed because tanker collisions may happen near the Bus Depot before, after or during delivery. A diesel spill or even a fire may result if the tanker is damaged during collision. The consultants have reviewed the risk assessment report of hydrocarbons transport in Hong Kong [], which provides failure frequencies for various road events and fire classes. Events studied included a full range of scenarios, and the frequencies of these events were of the order 10-13 to 10-10 per vehicle-kilometre. The spill frequency per year has been calculated by multiplying the spill frequency per vehicle-kilometre, vehicle deliveries per year (which is 4 tankers/day x 365 days/year) and the kilometres travelled in the vicinity of the Depot(which is assumed to be 0.1 km). The result is thus 10-11 - 10-8 spills per year The ignition probability, as stated in Table 8.6.2d, times the spill frequency per year gives the fire frequency per year (of the order of 10-13 to 10-10) caused by the transportation of diesel. The transportation risk, therefore, is insignificant and has no contribution to the overall results. This study further supports the arguments put forward in Section 8.4.3.8.

      1. Hazardous Impacts Analysis

        1. Having assessed the likelihood of incidents which could lead to fatal injuries at the Bus Depot in Section 8.6.2, it is now necessary to assess the probability of fatality and the likely numbers of fatalities.

          2. Scenarios B1-3, P1,and F1

        2. Section 8.5.1 described the complexities of modelling the effects of smoke ingress to the Bus Depot from a major fire at the oil terminal. Simple calculations have shown a survival time of as little as 5 minutes, which would apply to a major fire at the periphery of the terminal in which the smoke from the fire passes into the building with little or no dilution.

        3. Gaussian Dispersion from a continuous point source was used to study pool fires on cone roof storage tanks. The liquid burning rate provided by Babrauskas [] was taken to be the release rate for the calculation. At 100 m away from the point source, which is the approximate distance from the oil terminal to the Bus Depot, the concentrations of CO (1.2 ppm outdoors, 1.1 ppm indoors after half an hour) and CO2 (0.02 % outdoors, 0.018 % indoors after half an hour) are too low to cause any significant hazards to the Bus Depot, see Appendix S.

        4. For the present study an estimation on fatality has been made based on three key determinants of the risk: the size of the fire, its proximity to the Bus Depot and its duration. In all cases it is assumed that local conditions would cause the smoke and flames from the fire to blow directly towards the buildings (the wind direction probability is taken into account subsequently in the risk assessment).

        5. The numbers of fatalities for each scenario are determined after careful consideration of the severity of incidents and the size of the affected population. In the hazard assessment of the Joint Government Department Depot [xi], the maximum number of fatalities was assigned to be 100 with a risk population of about 1,000 (whilst the full capacity of the Government Depot is 3,500). The maximum occupancy of the Bus Depot, about one-half the risk population of the Government Depot, is taken to be the risk population in the analysis. This conservative estimation gives 50 people as the maximum number of fatalities at the Bus Depot.

        6. With reference to the hazard assessment report of the Government Depot [], fire in bund, pool fire with bund overtopping and pump farm pool fire are the largest fires at the oil terminal. Hence, it is assigned that:

  • 5 fatalities, 1 out of 10 people exposed to the hazard (smoke ingress) in the affected area may be killed with no FSD intervention; and

  • 1 fatality, one out of 50 people, may be killed with FSD intervention.

        1. Since fire on storage tank is a medium fire, its impact on the Bus Depot should be less severe. It is assigned that:

  • 1 fatality when there is no intervention of the FSD; and

  • No fatality when there is FSD intervention.

        1. A pool fire at the bulk filling station is assessed to be small and confined with no fatalities or significant impact posed to the Bus Depot are expected.

  • No one is killed with no intervention of the FSD; and

  • No one is killed with intervention of the FSD.

Scenarios FB1 and FB2

        1. Gaussian Dispersion from a continuous point source was used to study possible pool fire during tanker unloading. Results show that the outdoor concentrations of CO (14 ppm) and CO2 (0.2 %) are tolerable. The indoor concentrations are even lower. The occupants of the Government Depot should have more than 20 minutes to evacuate and there should not be significant impact to the surrounding area, see Appendix S.

        2. When there is a spillage during vehicle refuelling, only the driver doing the refuelling may be killed by the ignited fire, because there are fire extinguishers, FSD intervention, drencher system and appropriately rated fire doors will be used to segregate the refuelling area from the rest of the building. This will prevent fire-spread and escalation of smoke into the building; therefore, no other people should be hurt.

        3. The tanker is fitted with a manual push button shut-off valve which stops fuel flow when activated, thus limiting the size of spill. Because the tanker unloads outside the building in an open area, people should be able to evacuate to a safe place without difficulty. Since the pool fire is confined to 15 m around the spillage, the 18 kW/m2 zone of thermal radiation, corresponding to 1% fatality with an exposure time of 20 0seconds, should not exceed 19 m in diameter, see Appendix T. With a risk population of 1000 at the Government Depot, about 10 people (1% fatality) are conservatively assumed to be fatally injured when there is no FSD intervention and 1 with FSD intervention.

        4. Application of the above methodology to the various fire scenarios which have been identified for the oil terminal and the Bus Depot give the following results:

Table 8.6.3a Assessment of Impact of Smoke Ingress into Bus Depot

Scenario

Fatalities

Ref

Description

With FSD Intervention

Without FSD Intervention

B1

Fire on cone roof storage tank*

0

1

B2

Fire in bund

1

5

B3

Pool fire with bund overtopping

1

5

P1

Pump farm: pool fire

1

5

F1

Bulk filling station: pool fire

0

0

*assumed could spread to other tanks

 

Table 8.6.3b Assessment of Impact of Fire on Government Depot

Scenario

Fatalities

Ref

Description

With FSD Intervention

Without FSD Intervention

FB1

Spill during vehicle refuelling

0

1

FB2

Spill during tanker unloading

1

10

 

      1. Risk Assessment

        1. The final stage of the assessment is to combine the estimates of the likelihood of hazardous events occurring with estimates of their impact to determine the risk to people at the New World First Bus Permanent Depot and the occupants of the Government Depot. Risk can be expressed in either individual terms or societal terms for comparison against established criteria.

        2. In Hong Kong three measures of risk are usually evaluated:

          3. i. Societal risk (F-N curves), which expresses the risk to the population as a whole, is independent of geographical location. The F-N curve is a graphical representation of the cumulative frequency of N or more fatalities plotted against N on a log-log scale.

          ii. Societal risk (Potential Loss of Life or PLL), which also expresses the risk to the population as a whole and for each scenario and its location. The PLL is an integrated measure of Societal Risk widely used for assessing contributors to risk. The PLL is the sum of the outcome of multiplying each frequency of accident with its associated number of fatalities, as below:

          PLL = S F1 N1 + F2 N2 + Fn Nn ....

          iii. Individual risk (iso-risk contours), which expresses the risk to a single person in a specific location.

        3. The Hong Kong Government has established Risk Guidelines, which are presented The Hong Kong Planning Standards and Guidelines (HKPSG), Chapter 11. For developments in the vicinity of hazardous installations, the risks should lie within the acceptable limits of the Risk Guidelines, which are defined as follows:

· Individual Risk: The maximum involuntary individual risk of death associated with accidents arising at the hazardous facility should not exceed 1 chance in 100,000 per year (10-5/yr);

· Societal Risk: The societal risk should comply with the F-N diagram shown as Figure 3 in the HKPSG. The figure is a graphical representation of the cumulative frequency, F, of a number, N, or more fatalities resulting from potential accidents at a PHI plotted against N on a log-log scale. Three areas of risk are shown:

- Tolerable where risks are so low that no action is necessary;

- Intolerable where risks are so high that they should usually be reduced regardless of the cost or else the development should not proceed;

- ALARP (As Low As Reasonably Practicable) where the risks associated with each probable hazardous event at the hazardous facility should be reduced to a level 'as low as reasonably practicable', usually measured as a trade off between the risk reduction afforded and the cost of that reduction. Risk mitigation measures may take the form of engineered measures at the hazardous facility or development (i.e. population) controls in the vicinity of the facility. In the case of a new development in the vicinity of an existing hazardous facility the onus is on the developer to implement such measures as are necessary to ensure that risk levels at the development site are ALARP.

 

    2. Base Case Results

        1. The risk results for the proposed New World First Bus Permanent Depot and the off-site risk are summarised in Tables 8.7.1a and b below. The event trees and F-N curves are shown in Figures 8.2a, 8.2b, 8.3, 8.4a, 8.4b and 8.5 (FB1 is excluded because it only includes risk to the driver).

        2. Building on the assessment of the frequency of major fires at the oil terminal (Section 8.6.2) and the assessment of the consequences of a major fire (Section 8.6.3), three further mitigating factors are taken into account in the risk assessment:

          3. Wind direction

        3. It is assumed that there is a 0.25 probability of the wind blowing the smoke towards the Bus Depot building, based on a uniform wind rose. It is also assumed that there is a 0.5 probability of wind blowing smoke from pool fire of a tanker spill towards the Government Depot.

          4. Occupancy

        4. An occupancy probability of 1 is included in the calculations taking account of the working hours and working shifts of the New World First Bus Permanent Depot. There are always staff or maintenance workers in the Bus Depot. The occupancy of the Government Depot is 0.26 ((44 x 52)/(24 x 365)) because staff only work during office hours on weekdays.

          5. CRC/FSD or NWFB/FSD Emergency Response

        5. Account is taken of the response of CRC and the local emergency services to an incident at the oil terminal by assuming that in 2 out of 3 cases the response actions would be successful in reducing the number of fatalities. The same rule set is used for incidents at the Bus Depot on the spill during tanker unloading case. With all the fire fighting facilities and FSD intervention, the probability of successful mitigation for spill during vehicle refuelling is expected to be higher (0.9). The PLL and individual risk values calculated for various scenarios are shown below:

          6. Table 8.7.1a Risk Results Affecting the Bus Depot

          Scenario

          PLL

          Individual Risk

          Ref

          Description

          (per year)

          (per year)

          B1

          Fire on cone roof tank

          4.5 x 10-5

          9.1 x 10-7

          B2

          Fire in bund

          3.5 x 10-5

          7.0 x 10-7

          B3

          Pool fire with overtopping of bund

          3.5 x 10-6

          7.0 x 10-8

          P1

          Pump farm: pool fire

          3.5 x 10-6

          7.0 x 10-8

          F1

          Bulk filling station: pool fire

          0

          0

          Table 8.7.1b Risk Results from Bus Depot

          Scenario

          PLL

          Individual risk

          Ref

          Description

          (per year)

          (per year)

          FB1

          Spill during vehicle refuelling

          4.0 x 10-6

          4.0 x 10-6

          FB2

          Spill during tanker unloading

          4.1 x 10-6

          4.1 x 10-8

           

        6. The individual risk is calculated by dividing PLL by the total number of people exposed to the hazard. The maximum number of people affected at the Bus Depot is 50 and that of the surrounding population is 100. The IR values calculated are shown below:

          7. Table 8.7.1c Individual Risks Results

          Hazards

          Individual Risk

          posed by oil terminal on bus depot

          1.7 x 10-6

          posed by diesel storage on Gov’t population

          4.1 x 10-8

          posed by diesel storage on driver

          4.0 x 10-6

           

        7. From Tables 8.7.1a and b and Figures 8.4a, 8.4b and 8.5, it is apparent the risk levels at the New World First Bus Permanent Depot and risk posed its surrounding population are not significant.

        8. Individual risk levels at the Bus Depot and the Government building, after taking occupancies into consideration are below the Government Risk Guidelines of 1 x 10-5 per year for the maximum exposed individual.

        9. A major fire in the refuelling area at the Bus Depot is considered to be the highest risk. The calculations which have been undertaken for smoke ingress are necessarily simplified and no special protection features for the building (i.e. measures over and above normal BD and FSD requirements) are assumed.

        10. In the present case, survivability is not critically dependent on maintaining the integrity of the building, however the need to ensure adequate time for safe evacuation of the building is clear.

        11. The assessment has been based on fire scenarios in the Bus Depot and at the oil terminal which may be described as reasonably foreseeable. These include fires caused by spills during vehicle refuelling and tanker unloading, tank fires, bund fires at the oil terminal as well as accidents which could result in unconfined pool fire spreading around the site, possibly onto Chong Fu Road.

        12. The refuelling area is the highest risk area of the Bus Depot. An effective drencher system and fire segregation are required to control fire, prevent fire spreading and allow people to evacuate.

        13. Although the terminal handles mainly high flash point materials (diesel oils) fires can nevertheless occur due to overheating/catastrophic failure of pumps, lightning strikes on the tanks, poorly-controlled maintenance activities etc.

        14. From a brief inspection of the terminal by the Consultants, it would appear that the terminal is equipped with many of the normal features one would expect for a facility of its size and throughput.

    3. Analysis of Mitigation Measures

        1. A number of identified, feasible risk mitigation measures are considered in Table 8.8a.

          2.  

          Table 8.8a Risk Mitigation Measures

          Measure ID

          Candidate Risk Mitigation Measure

          Discussion

          Effect of Incorporation

          INCLUDED IN CBA?

          1

          Building Ventilation

          Local air intakes should not be close to the refuelling area inside the Bus Depot.

          Reduces the chance that smoke from a fire may be drawn into the building.

          No

          Already incorporated in design

          2

          Building Design

          Doors and windows on the side of the building facing CRC Oil Terminal should be minimised. All doors and windows should be capable of being effectively sealed and smoke tight.

          Reduces the chance that smoke from a fire may enter the building.

          Yes

          3

          		  

          The materials used for the construction of the exterior of the building on the side facing the CRC oil terminal should be non-combustible.

          Reduces the escalation potential of the building.

          No

          Already incorporated in design

          4

          Building Layout

          The building design should allow for rapid evacuation of people, via suitably protected routes, to the side of the building facing away from the CRC oil terminal to a safe muster area and thence to public thoroughfares leading away from the oil terminal.

          There are exits on three sides of the depot, NE, NW and SE. This is thought to be sufficient, and the SW adjoins another building.

          If the building is engulfed by smoke, the population must be able to escape to a safe place as easily as possible.

          No

          Already incorporated in design

          5

          		  

          Refuelling area is to be segregated by drencher system, which can be activated by the operation of any heat detector along the drencher line of the associated protected compartment plus manual control.

          The drencher system will contain the fire within the depot, and reduce the potential for escalation.

          No

          Already incorporated in design

          6

          		  

          Fire shutters should be used to block fire or smoke from getting into the evacuation routes.

          The automatic shutter system, specified in the original design, has been replaced by fire rated doors approved by FSD. As the doors will have equivalent fire rating and are required to swing shut, they are considered to be equivalent to the shutters.

          Reduce the probability of escalation into the building.

          No

          Already incorporated in design

          7

          		  

          There should be no exterior storage of dangerous goods on the side of the building facing the CRC oil terminal and flammable materials should be minimised around refuelling area.

          Reduce the probability of escalation of a fire from the CRC Oil Terminal.

          No

          Measure should be implemented.

          8

          Other

          Road tankers should maintain low speeds in the area around the Bus Depot to avoid collisions with other vehicles, tankers or objects.

          This will reduce the frequency and consequence of tanker collision incidents.

          No

          Measure should be implemented.

          9

          Emergency Plan

          Prepare an emergency plan for the office building to ensure the safety of personnel in the event of a fire in the bus depot, or oil terminal. An evacuation plan should be included, to be prepared in liaison with FSD. Proper training in the emergency plan should be carried out.

          This will reduce the frequency and consequence of tanker collision incidents.

          No

          Measure should be implemented.

           

        2. Table 8.8a recommends a number of mitigation measures which should be implemented as a matter of good practice, and identifies a mitigation measure which is to be taken forward into the cost-benefit analysis (CBA). CBA is widely used in QRA studies to evaluate the cost-effectiveness of alternative measures and provide a demonstration that all reasonably practicable measures have been taken to reduce risk.

        3. On the basis of the calculated risks, a simple calculation may be undertaken to gauge the level of expenditure which is justifiable on risk mitigation measures, as follows:

          4. Max. level of justifiable expenditure = PLL per year x value of life (HK$)

          x operating lifetime of Depot (years) x aversion factor

        4. A value of life of HK$24M has typically been used to date in Hazard Assessment in Hong Kong and it is adjusted to HK$33M in line with inflation, following the Consultants’ Methodology Report for the Reassessment of Chlorine Hazards for Eight Existing Water Treatment Works [].

        5. Depending on the level of risk, the value of life figure may be adjusted to reflect people’s aversion to high risk. An aversion factor of up to 20 is often used in Hong Kong SAR on CBA associated with QRA studies. This factor is applied against the ‘statistical value of life’ to give an equivalent much higher value of life. The aversion factor is applied to take account of society’s aversion to high multiple fatality accidents and an individual’s aversion to high (involuntary risk). The adjusted value of life using the aversion factor of 20 is HK$660M.

        6. The only mitigation measure that was identified for quantitative assessment in the CBA was:

          7. Sealing doors and windows against smoke.

          The PLL result for the mitigated case is 9.62E-06 per annum, therefore:

          Risk Reduction Achieved = 8.71E-05-9.62E-06 = 7.75E-05

        7. The Justifiable Expenditure on the Mitigation Measure is:

          8. 7.75E-05 x 33E6 x 50(yrs of operation) x 20 = HK$2.6 M.

        8. An estimated cost of effectively sealed doors and windows is HK$100,000 which is far less than the justifiable expenditure. Hence the measure is cost-effective to implement.

    5. Conclusions

      6. CRC Oil Terminal

        1. It is concluded that the risk to people working at the New World First Bus Permanent Depot due to the presence of the CRC oil terminal is tolerable. Individual risk levels are below the 1 x 10-5 per year and the societal risk levels are in the 'ALARP' region.

        2. The main hazard from the oil terminal arises from smoke ingress to the building in the event of a major fire at the oil terminal. The assessment which has been undertaken may be described as 'conservative' and assumes no special protection measures for the building. It also takes no account of smoke plume rise, which may mean that the plume will not impinge on the NWFB Depot.

        3. The mitigation measure of effective sealing of openings into which smoke could ingress on the side facing the CRC Oil Terminal was found to reduce the PLL from 8.71E-05 to 9.62E-06 per year, and reduced the FN curve to the "acceptable" level.

          4. Tanker Unloading

        4. The main hazard to the surrounding population from the diesel storage at the Bus Depot is spill during tanker unloading. The individual risk level is below 1 x 10-5 per year and the societal risk levels are in the ‘acceptable’ region. The frequency of a large spillage is low because the tankers are fitted with a manual push button shut-off valve that will stop fuel flow when activated. Also, international standards are followed with respect to tanker design. The tanker driver should be trained to the appropriate standard.

          5. Vehicle Refuelling

        5. The main hazard within the Bus Depot is a diesel spill in the refuelling area. However, a drencher system (with a 280 m3 water tank which gives a protection area of 877 m2) around the area and a four-hour F.R.P. fire shutter (activated by smoke detector and manual control) to prevent escalation of smoke into the building are provided. There should be adequate protection for people to evacuate to a safe area, in the unlikely event of a fire, via designated evacuation routes, and no one besides the driver should be affected. There is no off-site risk from the refuelling area. The individual risk level of the driver is below 1 x 10-5 per year.

       

    7. Recommendations

        1. The following mitigation measures should be implemented in accordance with the principle of reducing risks to as low a level as reasonably practicable:

        2. Reduce the openings (doors/windows) and ensure all openings can be effectively sealed against smoke ingress in the side of the building facing the CRC Oil Terminal.

        3. The party responsible for the management of the Bus Depot should develop an Emergency Plan. This should cover such aspects as:

  • the types of incident which could arise at the CRC oil terminal and NWFB Depot and their potential effects;

  • the means of alerting occupants of the Bus Depot and Government Depot;

  • the roles and responsibilities of key personnel at the Bus Depot;

  • closing of all doors and windows to stop smoke ingress;

  • the interface with the external emergency services;

  • emergency control points;

  • evacuation arrangements;

  • ending of the emergency; and

  • communications arrangements.

        1. Training should be provided for key personnel involved in implementation of the Plan. Exercises, including fire drills, should be regularly undertaken to enhance their capability to handle emergencies. After each exercise, the plan should be reviewed and kept up-to-date.

        2. The enclosed store room for DG should be provided on the side facing Chong Fu Road.

        3. Road tankers should maintain low speeds in the area around the Bus Depot to avoid collisions with other vehicles, tankers or objects.

    1. References

  1. Fax from New World First Bus Services Ltd. Dated on 12 August 1999.

  2. Quantitative Risk Assessment of Kong Pui Street Petrol Filling Stations, Rev C, IRMS/ERM Consortium, July 1999.

  3. Mudan, K.S., User’s manual for hydrocarbon pool and trench fire thermal radiation computer programs, Arthur D. Little, June 1987.

  4. Eisenberg, N.A. et al, Vulnerability model. A simulation system for assessing damage resulting from marine spills, Final Report AD/ A-015 245, US Department of Transport, US Coast Cuard, 1975.

  5. Cassidy and Pantony, Major industrial risks: a technical and predictive basis for on and off-site emergency planning in the context of UK legislation, Preventing Major Chemical and Related Accidents, p75, 1998.

  6. Shell International Oil Products BV, FRED, Version 2.2, 1995.

  7. Loss Prevention in the Process Industries, Vol. 1-3, Second Edition, Lees, 1996.

  8. Davies, T, Harding A B, McKay I P, Robinson, R G J and Wilkinson, A, Bund Effectiveness, in Preventing Escalation of Tank Farm Fires, TransIChemE, Vol 74, Part B, May 1996.

  9. Major hazard aspects of the transport and dangerous substances, UK Health and Safety Commission Advisory Committee on Dangerous Substances, 1991.

  10. Quantified Risk Assessment Report for the Risk Assessment of the Transport of Hydrocarbons in Hong Kong, Rev 1, DNV Technica, October 1996.

  11. Joint Department Depot in Chai Wan, ERM, 12 February 1999.

  12. Reassessment of Chlorine Hazards for Eight Existing Water Treatment Works: Methodology Report, Final Report, CE14/96, ERM, 24 September 1997.

  2. Summary of Environmental outcome

    1. Introduction

      1. This section summarised the key environmental outcomes arising from the EIA Study, including the population and environmentally sensitive areas protected, environmentally friendly designs recommended, key environmental problems avoided and the environmental benefits of environmental protection measures recommended.

    2. Environmental Benefits

      1. The results of the technical assessment indicated that the construction and operation of the proposed bus depot will not cause adverse environmental impact on the Environmentally Sensitive Areas. However, environmental protection measures are recommended in this EIA Report to protect the sensitive receivers from potential environmental impacts. To summarise, the environmentally friendly measures recommended and their environmental benefits are given in the following Table 9.2.1.

        2. Table 9.2.1 Summary of Environmental Benefits

        Environmentally Friendly Measures Recommended

        Key Environmental Problems Avoided & Environmental Benefits

        Buses are not allowed to travel on the section of Shing Tai Road facing Heng Fa Chuen during mid-night return and early morning leaving.

        Avoid noise nuisance to the residents at Heng Fa Chuen during mid-night return and early morning leaving.

        The new bus permanent depot to replace the existing temporary bus servicing/parking site. Buses will state at the new depot overnight instead of driving away to park at other places after cleaning and refueling at the temporary site during mid-night.

        Introduce noise reductions at some of the noise sensitive receivers at Heng Fa Chuen, Tsui Wan Estate and Staff Quarters due to the reduction in road traffic during mid-night return.

        A fleet rejuvenation programme involving 500 new environmentally friendly buses and, a refurbishment programme comprising engine conversion programme and catalytic converter installation to be implemented.

        Reduce bus exhaust emissions and hence benefit the air sensitive receptors along the bus routeing.

        Recycle of wastewater in the bus wash machines

        Reduce amount of wastewater produced.

        The new bus depot are designed with mechanical ventilation system to replace the existing old bus depot at Chai Wan Road, which do not have this kind of system.

        The air emission impacts on the workers working inside the depot can be minimised.

      2. The Environmentally Sensitive Areas and population protected that can be quantified have been identified and estimated. They are summarised in the following Table 9.2.2.

    Table 9.2.2 Environmentally Sensitive Areas and Population Protected

    Environmentally Sensitive Areas

    Estimated Population Protected During Mid-night Return (approximately)

    HK Technical College (Chai Wan) Staff Quarters facing Shing Tai Road

    150

    Heng Fa Chuen facing Shing Tai Road and Chong Fu Road

    2,400

    Tsui Wan Estate facing Wing Tai Road

    300

     

  4. overall conclusion and recommendation

    1. Introduction

      1. The objectives of the EIA were to describe the elements of the proposed bus depot that were to be assessed, define the standards and criteria which have been applied to the project, explain the methodologies employed in the assessments, identify potential impacts and potentially affected populations and environmental resources, provide a detailed assessment of environmental issues and impacts and make recommendations for reducing the potential impacts.

      2. The following technical assessments have been undertaken, for both the construction and operational phases of the proposed depot development:

    • Air Quality Impact Assessment;

    • Noise Impact Assessment;

    • Waste Management Impact Assessment;

    • Land Contamination Assessment; and

    • Hazard Impact Assessment.

      1. The key EIA findings and recommendations for the new bus depot are presented in the following sections.

    1. Air Quality Assessment

      2. Construction Phase

      1. The major dust generating activities during the construction phase have been identified as the construction works. The dust impact assessment confirms that predicted dust emissions will fully comply with the statutory limits. With the adoption of the proper dust control measures, compliance with the Air Pollution Control (Construction Dust) Regulation at the work site will control the potential dust nuisance to meet the established criteria. It is envisaged that the nearby ASRs would not be adversely affected by dust.

        2. Operational Phase

      2. The major air pollutant emissions are from the off-site bus traffic and the bus movement within the depot. The results of the quantitative studies indicate that the predicted air pollutant concentrations are well within the HKAQO limits at the nearby ASRs due to the emissions. No adverse impacts are anticipated with low air pollutant contributions from the depot to the neighbourhood.

        3.  

      3. With the proposed bus routeing that buses are not allowed to pass through the section of Shing Tai Road facing Heng Fa Chuen (Figure 3.1), it is envisaged that the nearby ASRs would not be adversely affected by the air emissions including the vehicular emission from the depot.

    2. Noise Assessment

      3. Construction Phase

      1. Due to the relatively large setback distances of greater than 150m between the construction site and the NSRs, the predicted construction noise levels are well below the criteria stipulated in the EIA-TM.

      2. No substantive construction noise mitigation programme will be required. However, recommendations including use of quiet plants and good site practices have been given to reduce further the construction noise impact and to conduct construction noise checks to assure compliance.

        3. Operational Phase

      3. The predicted noise levels from depot operation, on-site and off-site traffic are within the stipulated noise criteria at all identified NSRs. Plant noise will be suitably controlled (e.g. by silencers, acoustic louvres, etc) and is not expected to give rise to any adverse impact.

      4. The off-site traffic noise impact on the nearby NSRs will be minimised by proper routeing to avoid buses passing the section of Shing Tai Road facing Heng Fa Chuen during midnight return and early morning leaving. Improvement will also be made possible with the ingress and egress for the permanent depot via a new Road 20/6 (Figure 3.1), which is located farther away from Heng Fa Chuen when compared with that of the existing temporary servicing / parking site.

       

    3. Waste Management Impact Assessment

      1. The assessment of waste management has identified the various types and quantities of wastes expected to arise during the construction and operation phases. Wastes generated will include the normally anticipated excavated materials, construction and demolition materials, small volumes of chemical wastes, industrial wastes, general refuse and sewage. No significant impacts or concerns were identified due to the waste generated from the depot.

        2.  

      2. Good practices have been recommended to ensure that adverse environmental impacts are prevented and that opportunities for waste minimisation and recycling are followed.

      3. By implementing the waste management plan, the storage, handling, collection, transport and disposal of wastes should comply with regulatory requirements and no unacceptable environmental impacts should occur.

    4. Land Contamination Assessment

      1. The assessment of the potential for land contamination focused primarily on the diesel fuel storage tanks for the refueling facilities, the storage and handling of limited amount of chemicals and other dangerous goods.

      2. Appropriate operational practices (including inspection and monitoring arrangements and, reporting and recording of incidents), material and waste management strategies and precautionary measures for prevention of contamination problems will be adopted. In particular, the drills and training activities will be conducted to prevent and minimise the potential for spills and the subsequent contamination. Emergency procedures will be followed to manage the consequences of spills, leaks and other losses during the storage, transfer and handling of the fuel and other chemicals.

      3. The assessment concluded that there are no problems for land contamination associated with the construction and operation of the depot, provided that the proposed measures are implemented.

    5. Hazard Assessment

      1. The main hazard from NWFB Depot to the surrounding population was identified to be a fire caused by ignition of diesel spilled during tanker unloading. Although the frequency of bus refuelling is high, the drencher system provided around the refuelling area and FSD approved fire resistant doors will prevent fire-spread and escalation of smoke into the building should a spill ignite. Designated evacuation routes, will also be provided for people to evacuate in case of emergency. The individual risks and societal risks to the surrounding population from the diesel storage at the Bus Depot are acceptable.

      2. The main hazard from the nearby CRC oil terminal arises from smoke ingress to the Bus Depot in the event of a major fire at the oil terminal. It is concluded that the individual risk to people working inside the Bus Depot due to the presence of the oil terminal is acceptable and the societal risk lies within the 'ALARP' region. If the mitigation measure of effectively sealing the doors and windows is incorporated, the societal risk will be reduced to the acceptable region.

    7. Recommendations

      1. An Environmental Management Plan (EMP), which includes an Environmental Monitoring and Audit (EM&A) Manual and an outline Environmental Management System (EMS), has been proposed to confirm the effectiveness of all the proposed mitigation measures. Provided that the mitigation measures are adopted and implemented, environmental impacts associated with the construction and operation of the bus depot are amenable to mitigation during the project implementation.

    8. EM&A Requirements

      1. The EIA Study has identified the need to establish EM&A for the construction and operational phases of the proposed new bus depot. The EM&A requirements cover air, noise, waste, land contamination and hazard issues. The specific mitigation measures are presented in the Implementation Schedule as part of the EM&A Manual.

        2. Construction Phase

      2. The EM&A requirements identified for the construction phase are summarised in the following. Details are presented in the EM&A Manual.

Although the predicted levels of construction dust are well within the limits stipulated in the HKAQO, continuous surveillance of the implementation of dust mitigation measures will be carried on a weekly basis to ensure effective control of dust emissions.

As the predicted construction noise levels are within the limits stipulated in the EIA-TM, only a limited amount of daytime noise monitoring will be carried out for 30 active minutes on a bi-weekly basis. The preferred locations for noise monitoring will be at the HK Technical College (Chai Wan) and Staff Quarters, Heng Fa Chuen and Tsui Wan Estate.

    • Waste Management

Auditing will be carried out annually by the Independent Checker (IC) (Environmental) to ascertain whether the waste management procedures have been followed.

    • Land Contamination & Hazard

EM&A for land contamination and hazard are considered not necessary during the construction phase.

Operational Phase

      1. A detailed EM&A Manual for operational phase has been prepared to define the scope and programme, method and reporting requirements for the EM&A of the operation of the depot. The EIA study have identified the following recommendations for the operational phase :

    • Noise

The predicted off-site traffic noise impacts are insignificant provided that the following measures are taken by NWFB to reduce adverse noise impacts on the NSRs during the operational phase of the bus depot:-

- buses that run through the nearby roads will adhere to the suggested routeing prepared by the Traffic Consultant (MVA (HK) Ltd) (Figure 3.1); and

    • buses will not be allowed to travel on the section of Shing Tai Road facing Heng Fa Chuen during midnight return and early morning leaving.

The predicted operational noise levels caused by the depot are well within the limits stipulated in the EIA-TM. However, monitoring of operational plant will be undertaken to ensure that the source terms derived for the operational noise predictions are achieved both in terms of the vendor’s sound power specifications and the operational and maintenance assumptions.

A waste management plan will be employed to minimise potential adverse impacts associated with the solid waste and wastewater arising from operation of the depot.

Auditing of each waste stream will be carried out annually by an IC (Environmental) to determine if wastes are being managed in accordance with approved procedures and the site waste management plan and to see if waste reduction could be enhanced. The audits will cover all aspects of waste management including waste generation, storage, recycling, transport and disposal.

 

A contamination avoidance plan will be employed to prevent land contamination associated with contaminants arising from the operation of the depot.

Auditing will be carried out annually by the IC (Environmental) to determine if procedures and instructions in the contamination avoidance plan have been followed. Regular inspection, testing and checks are to be carried out on the following :

    • Daily inspections on fuel tanks to verify the valve positions and security, tank level checks for fuel leakage and oil/petrol interceptors to remove any accumulated sludge.

    • Annual tank integrity testing by an independent qualified surveyor or structural engineer to ensure sound condition of the diesel fuel tanks.

    • Annual checks by NWFB to ensure that appropriate measures are taken to avoid contamination due to chemical or oil leaks from vehicles or machinery.

    • Hazard

The establishment of safety management and emergency response systems for the depot operation will be adequate to reduce the likelihood of undesirable events and provide for their effective management.

    • Air

With the proper design of the depot and bus routeing, the operation of the depot will not cause adverse air emission impacts on the ASRs. EM&A for air quality is considered not necessary during operational phase.

    2. EMS Requirements

      1. The EIA Study has identified the need to establish EMS for the operational phase of the proposed new bus depot. An outline EMS with recommendations has been proposed and detailed in the EMP for the control of air, noise, waste and contamination issues.

      2. NWFB will ensure the facilities and programme are properly operated and maintained in accordance with the relevant operational requirements and targets. In addition, the potential environmental impacts and effectiveness of the mitigation measures will be monitored according to specific performance objectives, i.e. legal requirements and guidelines.

      3. NWFB will develop an EMS with reference to the requirements of ISO 14001 and relevant publications available from the Environmental Protection Department (EPD).