7. HAZARD TO LIFE

This section of the EIA presents a summary of the analysis and findings of the Hazard to Life Assessment (also referred as Quantitative Risk Assessment (QRA)) undertaken for the proposed South Island Line (East) (SIL(E)) project.

The railway extension project consists of an approximately 7 km long electrified railway system with five railway stations at Admiralty (ADM), Ocean Park (OCP), Wong Chuk Hang (WCH), Lei Tung (LET) and South Horizons (SOH). Construction is scheduled to commence in 2010 for completion in 2015.

The selection of construction methods has been optimised to minimise, as far as possible, the use of explosives depending on the type of material to be excavated. However, a significant amount of explosives will be required for the construction of rock caverns, tunnels and adits. It is envisaged that the following items of works for SIL(E) development will involve blasting.

¡ Rock excavation for Admiralty Station;

¡ Approximately 3.3 km long tunnel between Admiralty and Nam Fung Portal;

¡ A ventilation shaft located in Hong Kong Park;

¡ Site formation of Wong Chuk Hang Depot;

¡ Station cavern for LET and the approach tunnels, access tunnels and shafts (approximately 1.6 km);

¡ A ventilation and electrical and mechanical plant building at Nam Fung Road; and

¡ A ventilation and electrical and mechanical plant building at Lee Nam Road, Ap Lei Chau.

Excavation by blasting will be generally ongoing from November 2011 to August 2013.

As shown above, a substantial length of the tunnels and adits (approximately 6 km) will be excavated in rock. A significant amount of explosives will be required for the construction of rock caverns, tunnels and adits.

To enable a timely delivery of explosives to site and in order to meet the proposed construction work programme, one temporary Explosives Storage Magazine (Magazine) is required. It will be located at Chung Hom Shan. The site was selected considering the distance to the work areas as well as other constraints such as land availability, minimum separation distances from temporary magazine to populated area, accessibility by Mines Division, etc. (ref.1).

With reference to the EIA Study Brief (ESB-181/2008), if there is use of explosives for the construction activities and the storage or blasting location is in close vicinity to populated areas and/or Potentially Hazardous Installation site(s) along the Project alignment a hazard to life assessment is required.

With reference to the EIA Study Brief, some work areas and plant buildings will be located within the consultation zone of a PHI namely the Shell LPG Transit Depot/Bulk Domestic Supply at Lee Nam Road (the LPG Depot) which comprises a Bulk Domestic Supply facility with 40 tonnes of LPG storage in two mounted tanks and a Transit Depot with storage shed for about 2000 LPG cylinders (up to 100 tonnes). Based on this and as required in the EIA Study Brief Section 3.4.5.3, the hazard to life assessment for the LPG Depot has been carried out for the construction and operational stages of the Project. This is presented in Section 7.10 onwards.

The QRA for the storage and transport of explosives relates to the construction phase of the project, in which blasting activities are expected. There will be no explosives handled during the operational phase.

The Hazard to Life assessment under this section of the EIA, addresses, in particular, the following:

¡ Storage of explosives at the proposed temporary magazine (cartridged emulsion, detonating cord and detonators) including handling of explosives within the temporary magazine site;

¡ Transport of explosives to the delivery points; and

¡ PHI Hazard Assessment for the construction and operational phases of the Project.

Further details of the QRA for the Project are presented in the Appendix 7.

7.2 Legislation Requirement and Evaluation Criteria

The key legislation and guidelines that are considered relevant to the development of the proposed South Island Line (East) project are as follows:

¡ Dangerous Goods Ordinance, Chapter 295;

¡ Environmental Impact Assessment Ordinance (EIAO), Chapter 499; and

¡ The EIA Study Brief (ESB-181/2008), Section 3.4.5.

EIAO Technical Memorandum (EIAO-TM)

The requirement for a QRA of projects that involve the storage and transport of dangerous goods where a risk to life is a key issue with respect to the Hong Kong Government Risk Guidelines (HKRG) is specified in Section 12 of the Environmental Impact Assessment Ordinance Technical Memorandum (EIAO-TM).

The relevant authority for a QRA study relating to a temporary explosives magazine storage facility and the transport of the explosives is the Environmental Protection Department (EPD), as specified in Annex 22 of the EIAO-TM.

Annex 4 of the EIAO-TM specifies the Individual and Societal Risk Guidelines.

Hong Kong Government Risk Guidelines (HKRG), EIAO TM Annex 4

Individual risk is the predicted increase in the chance of fatality per year to an individual due to a potential hazard. The individual risk guidelines require that the maximum level of individual risk should not exceed 1 in 100,000 per year i.e. 1 x10^-5 per year.

Societal risk expresses the risks to the whole population. The HKRG is presented graphically in

Figure 7.1. It is expressed in terms of lines plotting the frequency (F) of N or more deaths in the population from incidents at the installation. Two F-N risk lines are used in the HKRG that demark “acceptable” or “unacceptable” societal risks. The intermediate region indicates the acceptability of societal risk is borderline and should be reduced to a level which is “as low as is reasonably practicable” (ALARP). It seeks to ensure that all practicable and cost effective measures that can reduce risk will be considered.

Figure 7.1 Hong Kong Government Risk Guidelines

7.3 Study Objectives and Methodology

The objective of the QRA study is to assess the risk to life of the general public from the hazards that arise from the storage and transport of the explosives that are required to facilitate the construction of the Project. The results of the QRA should then be compared with the HKRG.

The detailed requirements of the study are given in Section 3.4.5 of the EIA study brief. The main requirements are:

¡ To identify hazardous scenarios associated with the storage and transport of explosives; and then determine a set of relevant scenarios to be included in a QRA;

¡ To execute a QRA of the set of hazardous scenarios determined, expressing population risks in both individual and societal terms;

¡ To compare the individual and societal risks with the Criteria for Evaluating Hazard to Life stipulated in Annex 4 of the EIAO-TM; and

¡ To identify and assess practicable and cost-effective mitigation measures (e.g. selection of the shortest practicable road transport routes to and from the magazine).

The methodology of the hazard assessment should be consistent with previous studies having similar issues.

The elements of the QRA are shown schematically in Figure 7.2. It includes the following:

¡ Collection and review of relevant data for the proposed temporary Magazine, the transport from the temporary Magazine, and the use of explosives at the works area, as well as population and vulnerable receptors, such as slopes, retaining walls etc., in the vicinity of the storage, the tunnel construction and proposed transport routes;

¡ Hazard identification. A review of literature and accident databases were undertaken and updated. These formed the basis for identifying all the hazardous scenarios for the QRA study;

¡ Frequency estimation. The frequencies, or the likelihood, of the various outcomes that result from the hazards associated with the storage and transport of explosives was taken primarily from the XRL study (ref. 2), which has been accepted by the relevant authorities. Where necessary, to consider specific factors applicable for the Project, recent accident statistics, and to reflect the current knowledge on the explosives’ properties, these frequencies were modified or updated making reference, as far as possible to published references; such as the previous Hong Kong studies , UK HSE, US DoD, Dutch TNO, latest accident statistics from the Transport Department and Fire Service Department, etc.;

¡ For all identified hazards, the frequency assessment has been documented and the consequences were modelled;

¡ The frequency model related to the transport and storage of explosives was taken from the ERM 2009 study (ref. 2);

¡ The consequence model employed in this study is the ESTC model (ref.3), developed by the UK Health and Safety Commission (HSC). Although, there have been a number of recent studies suggesting that the ESTC (2000) models should be reviewed for applicability to explosive stores and transport, these models are still the recommended models in the UK and adopted in the WIL (ref.4) and XRL (ref. 2) studies;

¡ The consequence and frequency data were subsequently combined using ERM’s in-house proprietary software Riskplot ^TM to produce the required risk estimates. The transport part of the risk assessment, consistently with the XRL study (ref. 2), uses an in-house Explosive Transport GIS Risk Assessment tool (E-TRA) developed to account for three-dimensional blast effects on buildings and the effect of accidental explosions on elevated roads. It also accounts for traffic jam scenarios which could occur in some accidental scenarios as reported in ref.5. The E-TRA model is summarised in Section 3.2 of Appendix 7A and has been validated against Riskplot ^TM.

Finally, the results from the risk assessment were compared to the EIAO-TM Criteria. Recommendations have been made where required to ensure compliance with EIAO-TM Criteria, relevant best practice, and to reduce the overall risk levels.

Figure 7.2 Schematic diagram of QRA Process

The methodology used in this hazard assessment is consistent with previous studies. Details of the analysis can be found in Appendix 7.

7.4 Facility Details

7.4.1 Project Overview

The Project comprises the following key elements:

¡ Approximately 3.3 km long underground tunnel connecting the proposed underground station at Admiralty and the tunnel portal / box structure near Nam Fung Road (Nam Fung Portal);

¡ Approximately 2.0 km long railway viaduct including the railway bridge across the Aberdeen Channel from the Nam Fung Portal to the proposed tunnel portal near Sham Wan Towers (SWT portal), including two elevated railway stations at Wong Chuk Hang and Ocean Park;

¡ Approximately 1.6 km long underground tunnel connecting the proposed tunnel portal near Sham Wan Towers, the proposed underground railway stations near Lei Tung and at South Horizons;

¡ An at-grade railway depot at Wong Chuk Hang;

¡ A ventilation and electrical and mechanical plant building at Hong Kong Park adjacent to the British Council;

¡ A ventilation and electrical and mechanical plant building at Nam Fung Road adjacent to St. Paul’s Co-educational Primary School;

¡ A ventilation and electrical and mechanical plant building with associated access adit at Lee Wing Street, Ap Lei Chau; and

¡ Construction of a temporary above ground explosives magazine site at Chung Hom Shan.

The proposed Project alignment and work areas are shown in Figure 7.3.

The Project is scheduled to commence in 2010 for completion in 2015. Excavation in rock by blasting will be ongoing generally from November 2011 to August 2013 for a significant length of the tunnels, caverns and adits (approximately 6 km).

For the purpose of this study, the alignment is divided into two areas:

¡ Nam Fung Portal and Nam Fung Tunnel to Admiralty; and

¡ Ap Lei Chau: Lee Wing Street Construction Adit Portal, running tunnel to Lee Tung Station (LET), LET cavern top and bottom bench, tunnel from LET to Lei Tung Portal, LET entrance Adit B, LET Adit A and running tunnel to SOH.

Two categories of explosives will be used for the construction of tunnels, adits and caverns by Drill and Blast methods. These are:

¡ Initiating explosives: cartridged emulsion explosives, detonating cord and detonators; and

¡ Blasting explosives: bulk emulsion explosives or ammonium nitrate-fuel oil (ANFO) manufactured at the blast site or, in close proximity to sensitive receivers (i.e. with MIC less than 2 kg), cartridged emulsion explosives.

Cartridged emulsion and detonating cord will be delivered from the temporary explosives magazine to the various construction sites by the appointed contractors using Mines Division licensed trucks. These explosives are classified as an explosive Class 1.1D under United Nations (UN) Classification (ref. 6) and as a Category 1 (Explosive and blasting agents) Dangerous Goods under the Hong Kong Dangerous Goods Ordinance.

Detonators will also be used to initiate the blast at the working face. As used in this project, they are classified as Class 1.4B or 1.4S explosives under the UN classification system and Category 1 (Explosives and Blasting Agents) under the Hong Kong Dangerous Goods Ordinance, and will be transported from magazine to work areas by a dedicated truck, which is identical to, but independent of the truck carrying the emulsion explosives and detonating cord. Detonators approved for use in Hong Kong are of the Non-Electric Type, i.e. initiated by shock tube.

Explosives classified as Class 1.1 are defined as substances and articles which have a mass explosion hazard while Class 1.4 explosives present no significant hazard outside the packaging. To comply with the classification, it is required to ensure that the explosive is safe to transport, to pass a series of classification tests in accordance with the UN test manual, 2003 (ref.7). Due to different properties of explosives, a compatibility class is also assigned, as applicable to this Project. Type “B” is defined as “An article containing a primary explosive substance and not containing two or more protective features” and type “S” is defined as “The substance or article so packed or designed that any hazardous effects arising from accidental functioning are limited to the extent that they do not significantly hinder or prohibit fire fighting or other emergency response efforts in the immediate vicinity of the package”.

Bulk emulsion precursor will be transported to the blast sites by the appointed third party supplier. It is classified as an oxidising agent Class 5.1 under the UN Classification system and as Category 7, i.e. strong supporter of combustion under the Hong Kong Dangerous Goods Ordinance. Prior to sensitizing, it is not considered as an explosive, and hence outside the scope of this QRA. Bulk emulsion will not be stored within the temporary magazine.

Depending on blasting requirements, ANFO may be used in this Project. ANFO is classified as UN HD 1.1D under UN Classification. It consists of an oxidizing substance mixed with 6% by weight of diesel fuel oil. ANFO will be produced at the construction work area by using a mixing truck and hence outside the scope of this QRA.

7.4.2 Statutory/ Licensing Requirements

The statutory / licensing requirements with respect to the explosives (Cat. 1 Dangerous Goods) or the oxidizing substances (Cat. 7 Dangerous Goods) used to prepare explosives at the construction work area as well as relevant government departments/ authorities’ advice and practice on the proposed transport and storage of explosives for the blasting activities are summarized below.

Category 1 Explosives and Blasting Agents

¡ Responsible authority: The Commissioner of Mines

¡ Applicable regulations/ guidance notes:

- Supply of detonators and cartridged emulsion explosives (under the Dangerous Goods (General) Regulations Cap. 295B);

- Approved explosives for blasting in Hong Kong (under the Dangerous Goods (General) Regulations Cap. 295B);

- Blast design (under the Dangerous Goods (General) Regulations Cap. 295B);

- Blast loading and execution (under the Dangerous Goods (General) Regulations Cap. 295B);

- Removal of explosives (under Regulation 4 of the Dangerous Goods (General) regulations Cap. 295B);

- Approval of an explosives delivery vehicle (under CEDD’s “Guidance Note on Requirements for Approval of an Explosives Delivery Vehicle” (ref. 8));

- Explosive delivery vehicle design features and safety requirements (under CEDD’s “Guidance Note on Requirements for Approval of an Explosive Delivery Vehicle” (ref. 8);

- Explosive magazine (under CEDD’s document “How to Apply for a Mode A Explosives Store Licence” (ref. 9));

- Explosives produced at site (under Regulation 31A of the Dangerous Goods (General) Regulations Cap. 295B); and

- Explosives load per truck (in accordance with the Removal Permit under the Dangerous Goods (General) Regulations Cap. 295B).

Category 7 Strong Supporters of Combustion

¡ Responsible authority: Fire Services Department

¡ Applicable regulations:

- Storage of oxidizing agents (under Dangerous Goods (General) Regulations Cap. 295B)

This Project will use cartridged emulsion explosives as initiating explosives. For blasting explosives, bulk emulsion or ANFO will be used; however, cartridged emulsion explosives may be used as blasting explosives in close proximity to sensitive receivers. Therefore, the storage and transport requirements for explosives are the minimum required quantities for the Project.

7.4.3 Storage Magazine Details

A temporary magazine site is proposed to be built at Chung Hom Shan. The design, construction and operation of the temporary magazine will comply with the general requirements from the Commissioner of Mines (ref. 9).

The temporary magazine is generally designed to store sufficient quantities of explosives for two days so as to allow blasting to be carried out 24 hours per day and provide a buffer in the event of delivery interruption to the temporary magazine by Mines Division.

The temporary Magazine is required to serve the delivery points at Nam Fung Portal and Ap Lei Chau. Potential magazine site locations in both Hong Kong Island and Lamma Island have been investigated. Of these, only one site, in Chung Hom Shan, has been selected for locating the temporary Magazine based on the site selection process and the EIA Study Brief requirement. The site is located in an area of low population density.

The proposed temporary Magazine will have two stores. Contract 902 will have an allocated explosives store with an explosives storage capacity of 300 kg. Contract 904 will have an allocated store with a capacity of 500 kg. A storage chamber for detonators equivalent to two days supply is provided next to each explosives chamber. The detonators have a very low explosive mass and contain less than 1 gram of high explosives per detonator. The net explosive quantity within each detonator chamber will be less than 2 to 3 kg.

The work areas and the associated explosives using contract packaging for the temporary magazine are shown in Table 7.1.

Each of the magazine buildings is a single-storey, detached and bunded structure, which is fenced and secured in accordance with the Commissioner of Mines’ requirements. Details of the requirements are defined in the CEDD document “How to Apply for a Mode A Explosives Store Licence” (ref. 9). Surface road access suitable for 11-tonne trucks is also provided for the delivery of explosives.

Table 7.1: Project Contracts and Work Areas (Blasting only)

Contract No.	Storage Magazine	2 Days Explosives Storage requirement per Contract	Delivery Point (Work Area)
902	Chung Hom Shan	300 kg	Nam Fung Portal
904	Chung Hom Shan	500 kg	Lee Wing Street Construction Adit Portal (Ap Lei Chau)

7.4.4 Transport Route Details

Mines Division will deliver explosives to the temporary Magazine on a daily basis (once per day) by the shortest practicable route (at this stage it is difficult to predict the route, however it is the responsibility of Mines Division and outside the scope of this assessment), from where explosives will be transferred to the work areas by the contractors for the daily or twice-daily blasts depending on requirements for construction. Loads will be limited to a maximum of 200 kg per truck or less in accordance with the Removal Permit issued by Mines Division.

The explosives will be delivered to the various construction work areas using the public roads as shown in Figure 7.4. The proposed delivery points from the temporary Magazine are shown in Table 7.1.

According to the current construction programme, delivery of explosives to the two delivery points will be required from November 2011 to August 2013. The delivery programme to each work area will overlap significantly.

In addition to cartridged emulsion and detonating cord, detonators will also be transported. Detonators will be transported in a separate and dedicated licensed vehicle.

The licensed explosives delivery vehicles (LGV pick-up trucks) for delivery of explosives from the temporary site magazine to the worksites, used as the basis for this QRA, will have the following safety features:

¡ Diesel powered;

¡ Manual fuel isolation switch;

¡ Forward mounted exhaust with spark arrestor;

¡ All electrical wiring or electrical devices will be shrouded in fire resisting conduits;

¡ Fuel tank will be protected from accidental damage, and designed to prevent accumulation of spilt fuel on any part of the vehicle;

¡ Two fire extinguishers will be mounted on an easily accessible position on the vehicle;

¡ Fire resistant material will be fitted between the wheel arches and the goods compartment;

¡ Lockable wood lined steel or aluminium receptacles mounted on the vehicle tray; and

¡ Fold down / up explosives warning signs and rotating flashing light.

In addition, a fire screen will be fitted between the cab and the load compartment and between the load compartment and the chassis.

7.4.5 Base Case and Worst Case for Quantitative Risk Assessment

The actual construction programme will depend on the detailed design and appointed contractors. It may also depend on the actual achievable progress rates which may vary due to specific site conditions (e.g. geology). To consider the uncertainty in the envisaged construction programme, a Base Case, which accounts for expected programme variations, and a Worst Case, which presents the worst programme scenario, have been considered for the assessment.

Base Case programme for Hazard to Life Assessment

Based on the envisaged construction programme and sequence of works, the annual travel distance by explosives vehicles, carrying cartridged emulsion and detonating cord, will reach a peak in the period between March 2012 and February 2013, with an annual number of deliveries of 1,156 and a travel distance of around 10,911 km. This period is referred to as the peak explosives delivery period which is taken to represent the Base Case scenario for the Hazard to Life Assessment. The delivery frequency has been estimated on the basis that, for a given delivery point, each delivery will be made to each blast face independently of the other blast faces even if the load could be transported on the same truck. This approach, although slightly conservative, accounts for expected delivery variations during the peak delivery period, within which, separate deliveries will be generally undertaken.

The explosives load has been estimated on the basis that, for a particular delivery point, when the blast time for various faces coincides in the construction programme within the peak delivery period, explosives will be transported on the same truck. This applies, for instance, when the blast programme for various work areas at Ap Lei Chau.

The total number of trips has been estimated based on the typical licensing limit of 200 kg explosives per truck.

In the Base Case, it was considered that blasting could be carried out at predetermined times during the day following the envisaged construction programme. A distribution of delivery times has thus been considered based on the construction programme.

The Base Case programme is summarized in Table 7.2.

Table 7.2: Summary of Explosives Deliveries and Transport Quantities (for Base Case)

Delivery Point	Explosive Deliveries in Peak Delivery Period (trips/year)	Peak Transport Quantity (kg/trip)
Nam Fung Portal	572	41
	45	179
Lee Wing Street Construction Adit Portal (Ap Lei Chau)	539	200
Total	1156

Worst Case programme for Hazard to Life Assessment

The Hazard to Life Assessment also covers the Worst Case scenario. It addresses the possibility that, due to construction uncertainties or contractors’ methods of working, the contractors propose an actual construction programme which differs from the envisaged construction programme. Such a case may result in a higher number of delivery trips. Return trips loaded with explosives will generally be avoided; however, due to some construction uncertainties, a number of return trips could be made. Overall, in the worst case, a 20% increase in the number of deliveries compared to the base case scenario may result based on previous project experience.

In this project, for a particular delivery point, it is possible that the explosives load required for each delivery will be higher than that indicated in the envisaged programme due to particular site conditions and blasting requirements; however, the explosives load to be transported will be, as a worst case, the maximum explosives load for the site (sum of the loads for each blast face within the same work site). The delivery load, in the Worst Case Scenario, has been selected as the sum of the loads for each blast face within the same work site bearing in mind the licensing limit of 200 kg for the truck.

In this Worst Case Scenario, explosives could be delivered at peak day times.

The Worst Case programme is summarized in Table 7.3.

Table 7.3: Summary of Explosives Deliveries and Transport Quantities (for Worst Case)

Delivery Point	Explosive Deliveries in Peak Delivery Period (trips/year)	Peak Transport Quantity (kg/trip)	Length of Period Considered
Nam Fung Portal	629	41	9 months
	112	196	3 months (considering this quantity of explosives load is used for initial blasting within this period)
Lee Wing Street Construction Adit Portal (Ap Lei Chau)	647	200	12 months
Total	1,388

Tag	Scenario
Storage of Explosives
01	Detonation of full load of explosives in Store 1 in Chung Hom Shan site (Contract 902)
02	Detonation of full load of explosives in Store 2 in Chung Hom Shan site (Contract 904)
03	Detonation of full load of explosives in one contractor truck on the access road within Chung Hom Shan magazine site boundary
Transport of Explosives
04	Detonation of full load of explosives in one contractor truck on public roads – from Chung Hom Shan site to Nam Fung Portal delivery point
05	Detonation of full load of explosives in one contractor truck on public roads – from Chung Hom Shan site to Ap Lei Chau delivery point

7.9.2 Societal Risk Results

The societal risk results for explosives storage and transport for the SIL(E) project have been combined to produce the overall societal risk results for the base case and the worst case (Figure 7.7).

The Base Case represents the risks associated with the envisaged blasting programme. It can be seen that the risks lie in the ALARP region.

The Worst Case represents the maximum risks associated with the worst blasting scenario. The risks, as expected, are higher than the base case but still within the ALARP region.

Figure 7.7 F-N Curves for Storage and Transport of Explosives

Figure 7.8 shows the F-N curve for the Base Case with a breakdown by storage and transport. It is observed that risks from the temporary magazine are negligible compared to the transport risks. Indeed, the temporary magazine is located in a remote area with very low population density nearby.

The F-N curves for both base case and worst case are within the As Low as Reasonably Practicable (ALARP) Region as per HK EIAO-TM. Therefore, mitigation measures need to be considered to reduce the risk. The ALARP assessment is provided in Section 9 of Appendix 7A.

The Potential Loss of Life (PLL) for the base case and the worst case are given in Table 7.5 and Table 7.6 respectively. The PLL for this Project has been evaluated at 1.25 x 10^-4 per year. The maximum PLL value for the Project is estimated at 1.58 x 10^-4 per year, which is obtained from the worst case.

Figure 7.8 F-N Curves for Base Case with Breakdown by Transport and Storage

Table 7.5: Potential Loss of Life for Base Case

Base Case	PLL (per year)	Percentage Contribution (%)
Storage of Explosives
Chung Hom Shan Magazine	1.11E-08	0.009%
Transport of Explosives
Chung Hom Shan Magazine to Ap Lei Chau	9.09E-05	72.83%
Chung Hom Shan Magazine to Nam Fung Portal	3.39E-05	27.16%
Total	1.25E-04	100.00%

Table 7.6: Potential Loss of Life for Worst Case

Base Case	PLL (per year)	Percentage Contribution (%)
Storage of Explosives
Chung Hom Shan Magazine	1.11E-08	0.007%
Transport of Explosives
Chung Hom Shan Magazine to Ap Lei Chau	1.14E-04	72.15%
Chung Hom Shan Magazine to Nam Fung Portal	4.40E-05	27.85%
Total	1.58E-04	100.00%

7.9.3 ALARP Assessment

Since the risks posed by the Project, for both cases considered, are within the ALARP region specified in EIAO-TM Annex 4, this implies that risk reduction measures and / or alternate options should be explored for the Project.

It was found that the risks arising from explosives transport are much more significant than that of the explosives storage; hence the ALARP assessment focuses on the transportation aspects of explosives.

Where the risk falls into the ALARP region, the risks associated with each probable hazardous event should be reduced to a level ‘as low as reasonably practicable’. This firstly requires the identification of any ‘practicable’ options regardless of their cost. A mitigation option is considered ‘practicable’ if an engineering solution exists and can be implemented on the SIL(E) project regardless of the cost without affecting the project construction programme. Secondly, the extent to which the risk should be reduced is usually measured as a trade off between the risk reduction, i.e. the safety benefits and the cost of the risk reduction measure. A mitigation option is considered ‘reasonable’ if the cost of implementing the option is not grossly disproportionate to the achieved safety benefits.

Risk mitigation measures may take the form of engineered measures, controls in the zones most impacted by the hazardous scenarios presented by this project, or operation and procedural controls.

Approach to ALARP Assessment

The approach consists of identifying potential justifiable mitigation measures, assessing their practicability for this Project and evaluating their cost and comparing with the safety benefits of implementing the measures. Combinations of mitigation measures are also considered.

The safety benefits are evaluated as follows:

Safety Benefits = Value of Preventing a Fatality x Aversion Factor x Reduction in PLL value

x Design life of mitigation measure

The Value of Preventing a Fatality (VPF) reflects the tolerability of risk by the society and therefore the monetary value that the society is ready to invest to prevent a fatality. For the purpose of this assessment and for consistency with previous studies, the Value of Preventing a Fatality is taken as HK$33M per person, which is the same figure as used in previous Hazard Assessment studies (derived from ref. 17 but updated to current prices).

Depending on the level of risk, the value of preventing a fatality may be adjusted to reflect people’s aversion to high risks or scenarios with potential for multiple fatalities. The methodology for application of the ‘aversion factor’ follows that developed by EPD (ref. 18), in which the aversion factor is calculated on a sliding scale from 1 (risks at the lower boundary of the ALARP region of the Risk Guidelines) up to a maximum of 20 (risks at the upper boundary of the ALARP region). The adjusted VPF using the aversion factor of 20 is HK$660M. This value is a measure of how much the society is willing to invest to prevent a fatality, where there is potential for an event to cause multiple fatalities.

With reference to Appendix 7A, the maximum justifiable expenditure for this Project is calculated as HK$ 0.21M assuming the design life of the mitigation measure is 2 years based on the construction phase of the SIL(E) project during which storage and transport of explosives will be involved, with the PLL of 1.58 x 10^-4 per year, which is obtained from the Worst Case.

For an ‘achievable’ mitigation measure to be potentially justifiable, its cost should be less than the Maximum Justifiable Expenditure.

Potential Justifiable Mitigation Measures

The potential options that have been examined in the ALARP assessment include the following categories.

¡ Options eliminating the need for a temporary Magazine or eliminating the risk (e.g. Use of alternative methods of construction (‘hard rock’ TBMs));

¡ Options reducing significantly the distance run by contractors’ explosive trucks such as closer magazine sites and alternative routes. The temporary magazine and route options considered are summarised below:

- Numerous alternative magazine sites to Chung Hom Shan were considered (Appendix 7A).

- However, none of the alternative candidate sites could either meet the Commissioner of Mines’ external separation requirements or are located farther than the proposed magazine. Therefore, no alternative temporary magazine site option has been considered for the ALARP assessment.

- Based on the review of the possible transport routes for the SIL(E) project, it has been noted that the driving direction from the temporary Magazine along Chung Hom Kok Road, Repulse Bay Road, Island Road and Wong Chuk Hang Road to the two work areas is the shortest practicable route. There is no alternative route of similar distances identified. Therefore, the possibility of using an alternative transport route for the delivery is not considered further.

¡ Options reducing significantly the quantities of explosives to be used such as use of ‘hard rock’ TBM or alternatives to cartridged emulsion.

¡ Options reducing significantly the number of trips to be carried out by contractors’ explosives trucks:

- As typically required by Mines Division, the amount of explosives that a 3rd party contractor’s truck can transport from the temporary magazine to the blast sites is limited to a maximum of 200 kg per truck at the moment. This limit may necessitate more than one trip to deliver the required volume of explosives for a blast in some circumstances following the envisaged SIL(E) construction programme, particularly relevant to the Ap Lei Chau construction area.

For a particular blast time, the overall number of trips can be significantly reduced by transporting all the required explosives load for the cavern/ tunnels/ adits/vent duct of the same work area on the same delivery truck. Where the explosives load is higher than 200 kg limit per truck, a higher load up to 250 kg per truck may be permitted to be transported. This will reduce the number of additional deliveries while at the same time not cause any significant increase in the consequences due to the higher load.

Although, this will increase the explosives load transported on the delivery trucks, the total number of explosives deliveries during the construction period will be significantly reduced. This may offer some significant risk reduction. This option is selected for further analysis.

¡ Options considering improved explosives truck design; and

¡ Options considering better risk management systems and procedures.

In summary, the following option has been considered for cost-benefit analysis.

¡ Option 1: Reduction of Explosives Transport Frequency

The PLL for Options 1 is compared to the PLL for the Worst Case in Table 7.7. This was used as the basis for the cost-benefit analysis/ ALARP assessment presented in Table 7.8.

Other options considered practicable have been either recommended for implementation or assessed comparing the implementation cost with the maximum justifiable expenditure. The evaluation for each option is shown in Table 7.8. More details are available in Section 9 of Appendix 7A.

Table 7.7: Potential Loss of Life for Worst Case and Option 1

Case	PLL (per year)
Worst Case	1.58E-04
Option 1: Reduction of Explosives Transport Frequency	1.56E-04

Table 7.8: ALARP Assessment Results

Option Description	Practicability	Implementation Cost	Safety Benefits or Justifiable Expenditure	ALARP Assessment Results
Use of alternative methods of construction (TBMs)	Not Practicable	> HK$ 100M	HK$ 0.21M	Not Justified
Use of Magazines Closer to the Construction Sites	Not Practicable	-	-	Closest practicable magazine site to the construction sites has been selected
Use of Alternative Route	Not Practicable	-	-	Not Justified
Use of different explosive types (different types of detonating cord)	Pose some limitations	HK$ 1M	No safety benefit	Not Justified
Use of smaller quantities of explosives	Practicable	> HK$ 0.9M	HK$ 0.9M	Use of cast boosters is not cost effective.The cast booster option will be explored further in line with the use of best practice in explosives selection.^[1]
Safer explosives truck (reduced fire load)	Practicable	-	-	Based on low implementation costs, this option has been directly incorporated in recommendations
Lower Frequency of Explosives transport (Option Case 1)	Practicable upon Mines Division approval	-	HK$ 0.0026M	Justified.
Reduction of Accident Involvement Frequency (training programme etc.)	Practicable	-	-	Based on low implementation costs, this option has been directly incorporated in recommendations
Reduction of Fire Involvement Frequency (better emergency response, extinguisher types etc.)	Practicable	-	-	Based on low implementation costs, this option has been directly incorporated in recommendations

Note: [1] Please refer to SIL (E) Hazard to Life Assessment Final Report, Section 9.4.7, 8^th paragraph

7.9.4 Cumulative Risk Assessment

Cumulative risk assessment analyses the combined risks of fatality arising from exposure to hazards due to storage, handling and transport of dangerous goods in various projects being undertaken concurrently.

The projects that could potentially interface with the SIL(E) Project are: the West Island Line (WIL) Project, the Repositioning and Long Term Operation Plan of Ocean Park, the Shatin to Central Link - Cross Harbour Section, and the Drainage Improvement in Northern Hong Kong Island - Hong Kong West Drainage Tunnel. Although there is some programme overlap with some of these projects none are geographically aligned with the SIL(E) placement (alignment, worksites, magazine site or transport routes). The decking of the Wong Chuk Hang Nullah is now part of the SIL(E) project and will be carried out by MTR Staff and/or MTR Contractors, who are not considered as members of the public in terms of risk.

Therefore there is no cumulative risk to be considered.

7.10 PHI Hazard Assessment for Construction and Operation Phases of the Project

7.10.1 Introduction

This Section summarises the methodology and results of the Hazard Assessment (HA) for the LPG Transit Depot/Bulk Domestic Supply at Lee Nam Road (the LPG Depot) in connection with the construction and operation of the South Island Line (East) (SIL(E)). The detailed HA report is provided as Appendix 7B.

The LPG Depot is designated as a Potentially Hazardous Installation (PHI). Part of the proposed work sites and plant buildings as well as the South Horizons station will be located within the 500 m Consultation Zone of the LPG Depot and therefore a hazard assessment is required

Purpose of the PHI Hazard Assessment

Section 3.4.5 of the EIA Study Brief for this project (ESB-181/2008) specifies Hazard to Life assessments to be conducted. Part of this requirement addresses risks in relation to the LPG Depot as follows:

The Applicant shall carry out hazard assessment to evaluate potential hazard to life during construction and operation stages of the Project due to the LPG Depot.

The hazard assessment shall include the following:

(i) Identify hazardous scenarios associated with the facilities/activities of the LPG Transit Depot/Bulk Domestic Supply at Lee Nam Road and then determine a set of relevant scenarios to be included in a Quantitative Risk Assessment (QRA);

(ii) Execute a QRA of the set of hazardous scenarios determined in (i), expressing population risks in both individual and societal terms;

(iii) Compare individual and societal risks with the criteria for evaluating hazard to life stipulated in Annex 4 of the TM; and

(iv) Identify and assess practicable and cost-effective risk mitigation measures.

The methodology to be used in the hazard assessment should be consistent with previous studies having similar issues.

The LPG Depot is designated as a Potentially Hazardous Installation (PHI) owing to its two main facilities on the site: a Bulk Domestic Supply facility with 40 tonnes of LPG storage in two mounded tanks and a Transit Depot with storage shed for about 2,000 LPG cylinders (up to 100 tonnes). Part of the proposed work sites and plant buildings as well as the South Horizons station will be located within the 500 m Consultation Zone of the LPG Depot.

Societal risks from a PHI depend on surrounding population levels. Consultation Zones are established around PHIs to control developments in the vicinity and prevent population accumulating to the point where societal risks may become unacceptable. Any new development within the Consultation Zone of a PHI that may lead to an increase in population, requires a hazard assessment to be conducted to ensure that the societal risks remain acceptable. The purpose of this assessment, therefore, is to assess risks from the LPG Depot to the surrounding population including the construction and operational phases of SIL(E). The criteria and guidelines for assessing Hazard to Life are stated in Annexes 4 and 22 of the Technical Memorandum (EIAO-TM Criteria).

Figure 7.9 Location of South Horizons Station and the LPG Depot

7.10.2 General Methodology

An assessment was conducted previously for the LPG facilities at Ap Lei Chau as part of the Harbour Area Treatment Scheme (HATS) (ref. 19). The methodology adopted in that study is followed closely in the current study with some refinements. Details are presented in Appendix 7B.

It should be noted that the separation between the South Horizons work sites and the PHI is such that activities at the work sites will not impact on the LPG Depot. Blasting, for example, will all be underground and at distances significantly greater than that required to inflict damage on the LPG facilities. Potential impacts of construction activities on the LPG Depot are therefore not considered further in this assessment. On the other hand, incidents at the LPG Depot may extend up to a few hundred metres and may impact on the South Horizons station and/or worker population and needs to be assessed.

The South Horizons construction phase will overlap with construction work for the Preliminary Treatment Works (PTW) in Ap Lei Chau as part of the HATS project. The assessment therefore considers the increase in population due to both groups of workers. Three population cases are considered in the analysis:

¡ The current (2009) population;

¡ The construction phase (2014) population with overlapping construction activities between MTR South Horizons works and HATS works; and

¡ A future operational case with 2031 population.

Although the South Horizons construction phase may continue to 2015, the HATS construction is expected to be completed in 2014. Year 2014 was therefore selected as an appropriate year for the construction phase since the worker population will be at its highest during this time.

7.10.3 Shell’s Facilities at Ap Lei Chau

Shell’s LPG facility consists of an LPG Bulk Domestic Supply (LPG Compound) and a Transit Depot (Figure 7.10). The LPG Compound is located on the south side of the site while the Transit Depot (LPG Storage Shed) is situated on the north side. Deliveries are made by road tankers and cylinder wagons using Dangerous Goods ferries that berth at a jetty on the northwest of the site. An area for parking LPG road tankers and cylinder wagons is provided in front of the Storage Shed.

Figure 7.10 Layout of the LPG Depot

Basic Operating Data

Detailed description of the LPG Depot operations and relevant safety features is given in Appendix 7B.

A summary of the Bulk Compound and the Transit Deport operating data (Shell, 2009) is provided in Table 7.9 and Table 7.10 respectively.

Table 7.9: Plant Operating Data for Bulk Domestic Supply Facility

Description	Number
LPG road tanker deliveries	3 per day (1 ro-ro ferry round trip)
LPG road tanker size	9 tonne
LPG storage	2 ´ 20 tonne mounded tanks (filled to 85% = 34 tonnes)
Storage pressure	~ 3.5 barg
Unloading time	2 hours
Vaporisers	5 hot water heaters + 2 electric heaters

Table 7.10: Plant Operating Data for Transit Depot

Description	Number
LPG cylinder wagon deliveries	3 per day (1 ro-ro ferry round trip)
Cylinder throughput	900 per day max (277,000 average per year)
Cylinder storage	Max 4,300, average 2,200
Cylinder transport to customers	Distributors’ wagons. 5.5 tonne (65 cylinders) or 8 tonne (125 cylinders)
Cylinder size distribution	2 kg – 8%
	8 kg – 24%
	10.5 kg – 5%
	13.5 kg – 39%
	15 kg – 8%
	49 kg – 16%
Storage pressure	~ 3.5 barg
Construction	Storage shed with open walls and natural ventilation
Safety systems	4 gas detectors with automatic water sprinklers and hydrants.

7.10.4 Population Data

Population in the vicinity of the LPG Depot was based on the HATS study (ref. 19), data from the Census and Statistics Department for mid 2006 and site surveys. The population data were then updated to reflect the current situation and the current projections to the assessment years for construction and operational phases of the project assuming a population growth of 1% per year, consistent with previous studies in Hong Kong (ref. 2).

The future 2031 case considers the South Horizons MTR station during the operational phase. Operation of the MTR will likely shift patronage away from buses and onto the trains. This may change outdoor population distributions at street level. For simplicity, the analysis conservatively assumes outdoor population will grow at the same rate as indoor population i.e. by 1% per year. No redistribution in population is imposed due to the construction of the MTR station.

The population data methodology and the final population data used in this study are detailed in Appendix 7B.

7.10.5 Meteorological Conditions

Meteorological conditions affect the dispersion behaviour of gas releases, particularly the wind speed, wind direction and atmospheric stability class. Weather data from the most recent 5 years (2004 to 2008) from Wong Chuk Hang weather station of the Hong Kong Observatory were used in the analysis. These weather data were rationalised into 5 categories to represent the range of weather conditions expected at the site. These categories were selected by reference to the HATS study (ref. 19). The probabilities of occurrence of each combination during day and night are presented in Appendix 7B (Table 2.5).

7.10.6 Hazard Identification

A survey of worldwide accidents involving LPG facilities and transport has been conducted. Details are provided in Appendix 7B.

Based on the incident review, the main hazard associated with an LPG facility is an uncontrolled release of LPG resulting in a fire or explosion upon ignition. There is also the potential for escalation of a fire event to cause a Boiling Liquid Expanding Vapour Explosion (BLEVE) of the LPG road tanker or the cylinders and this may produce fragments that can travel hundreds of metres. Connection/ disconnection errors and tanker drive away during unloading can also lead to leaks. The initiating events leading to an LPG release event and the possible outcomes are presented in Appendix 7B.

Table 7.11 summarises the representative LPG release events considered in the assessment. Details are provided in Appendix 7B.

Table 7.11: Release Scenarios Considered

Equip. ID	Equipment Description	Event Description	Release Type	Hole Size	Potential Hazardous Event Outcomes
1	Storage vessel	Catastrophic failure	Instantaneous	Rupture	Fireball, VCE, flash fire
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire
2	LPG road tanker	Catastrophic failure	Instantaneous	Rupture	Fireball, VCE, flash fire
		Partial failure	Continuous	2” leak	Jet fire, VCE, flash fire, BLEVE
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire, BLEVE
3	Filling line to storage vessel	Guillotine failure	Continuous	Pipe full bore	Jet fire, VCE, flash fire
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire
4	Flexible hose	Guillotine failure	Continuous	Hose full bore	Jet fire, VCE, flash fire
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire
5	Line from storage vessel to vaporizers	Guillotine failure	Continuous	Pipe full bore	Jet fire, VCE, flash fire
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire
6	Vaporizer	Guillotine failure	Continuous	Pipe full bore	Jet fire, VCE, flash fire
7	Send-out piping downstream of vaporizers	Guillotine failure	Continuous	Pipe full bore	Jet fire, VCE, flash fire
		Partial failure	Continuous	1” leak	Jet fire, VCE, flash fire
8	LPG cylinder	Catastrophic failure	Instantaneous	Rupture	Fireball, flash fire
		Partial failure	Continuous	1mm leak	Jet fire, flash fire, BLEVE
9	Petrol/diesel road tanker	Catastrophic failure	Instantaneous	Rupture	Pool fire
		Partial failure	Continuous	1” leak	Pool fire

7.10.7 Frequency Analysis

Base Event Frequencies

The previous HATS study (ref. 19) performed a detailed Fault Tree Analysis (FTA) to assess the frequency of each failure listed in Table 7.11. This included consideration of causes such as spontaneous failures, overfilling, truck collisions, connection/disconnection errors etc. and took credit for safety systems such as operator intervention, check valves, excess flow valves, pressure relief valves etc. These frequencies were checked and found to be broadly consistent with those of previously approved studies in Hong Kong (for example, ref. 4, 20 & 21). In this assessment, the same frequencies were largely adopted with minor changes made to scale frequencies to reflect updated information provided by the depot operator (ref. 22). Details can be found in Appendix 7B.

Base event frequencies adopted in this study are summarised in Table 7.12 and Table 7.13 for the LPG Compound and LPG Transit Depot respectively. Details are provided in Appendix 7B.

Table 7.12: Base Event Frequencies for the LPG Compound

Event Description	Failure Rate (per year)
Cold catastrophic failure of storage vessel	6.72 ´ 10^-7
Cold partial failure of storage vessel	1.17 ´ 10^-5
Cold catastrophic failure of road tanker	1.48 ´ 10^-7
Cold partial failure of road tanker	3.62 ´ 10^-7
Rupture of filling line to storage vessel	5.14 ´ 10^-7
Leak of filling line to storage vessel	7.69 ´ 10^-7
Rupture of flexible hose	3.82 ´ 10^-5
Leak of flexible hose	3.92 ´ 10^-5
Rupture of line from storage vessel to vaporizers	4.00 ´ 10^-6
Leak of line from storage vessel to vaporizers	1.30 ´ 10^-5
Rupture of vaporizer	3.64 ´ 10^-8
Rupture of send-out piping downstream of vaporizers	4.00 ´ 10^-6
Leak of send-out piping downstream of vaporizers	1.30 ´ 10^-5
Rupture of LPG cylinder in storage shed	2.20 ´ 10^-3
Leak of LPG cylinder in storage shed	5.72 ´ 10^-3

Table 7.13: Base Event Frequencies for the Transit Depot

Event Description	Failure Rate (per year)
Road Tanker / Cylinder Wagon Transport Events
Cold rupture of road tanker	5.69 ´ 10^-7
Large liquid release from road tanker	3.94 ´ 10^-6
Large vapour release from road tanker	4.60 ´ 10^-7
Medium liquid release from road tanker	1.49 ´ 10^-6
Rupture of LPG cylinder on wagon	6.13 ´ 10^-6
Cold rupture of petrol tanker(1)	1.25 ´ 10^-7
Liquid release due to leak from petrol tanker(1)	3.13 ´ 10^-7
Cold rupture of diesel tanker(1)	8.33 ´ 10^-8
Liquid release due to leak from diesel tanker(1)	2.08 ´ 10^-7
Road Tanker/Cylinder Wagon Stationary Events
Cold rupture of road tanker	2.08 ´ 10^-9
Large liquid release from road tanker	1.88 ´ 10^-9
Large vapour release from road tanker	1.88 ´ 10^-9
Medium liquid release from road tanker	1.88 ´ 10^-9
Rupture of LPG cylinder on wagon	3.54 ´ 10^-7
Rupture of LPG cylinder on wagon while parked overnight(2)	1.70 ´ 10^-5

· (1) Frequency calculated based on failure rate of 5´10^-6 per tanker-year for a 1” leak, 2´10^-6 per tanker-year for rupture (ref. 23) and presence time of half an hour for each tanker.

· (2) Frequency calculated based on failure rate of 6.8´10^-6per vehicle-year, for 5 wagons parked overnight for 12 hours per day.

Event Tree Analysis

Event tree analysis (ETA) is used to model the evolution of an event from the initial release through to the final outcome such as jet fire, fireball, flash fire etc. This may depend on factors such as whether immediate or delayed ignition occurs, or whether there is sufficient congestion to cause a vapour cloud explosion.

In this assessment, the event trees for the failure of a storage vessel, LPG road tanker, hose and piping, LPG cylinder and transit depot were derived. The frequencies of hazardous outcomes for the LPG Compound and the Transit Depot are summarised in Table 7.14 and Table 7.15 respectively. Details are presented in Appendix 7B.

Table 7.14: Event Outcome Frequencies for the LPG Compound

Equipment Description	Event Description	Outcome	Outcome Frequency (per year)
Storage vessel	Rupture	Fireball	2.02´10-7
		VCE	4.70´10-8
		Flash fire	1.88´10-7
	Leak	Jet fire	8.19´10-7
		VCE	1.09´10-7
		Flash fire	4.35´10-6
Road tanker	Rupture	Fireball	4.44´10-8
		VCE	1.04´10-8
		Flash Fire	4.14´10-8
	Leak	Jet fire	2.51´10-8
		VCE	3.37´10-8
		Flash fire	1.35´10-7
	Escalation events	BLEVE	2.11´10-10
Filling line to storage vessel	Full bore rupture	Jet fire	3.60´10-8
		VCE	4.78´10-8
		Flash fire	1.91´10-7
	Leak	Jet fire	5.33´10-8
		VCE	7.15´10-8
		Flash fire	2.86´10-7
Flexible hose	Full bore rupture	Jet fire	2.67´10-6
		VCE	3.55´10-6
		Flash fire	1.42´10-5
	Leak	Jet fire	2.74´10-6
		VCE	3.65´10-6
		Flash fire	1.46´10-5
Line from storage vessel to vaporisers	Full bore rupture	Jet fire	2.80´10-7
		VCE	3.72´10-7
		Flash fire	1.49´10-6
	Leak	Jet fire	9.10´10-7
		VCE	1.21´10-6
		Flash fire	4.84´10-6
Vaporisers	Full bore rupture	Jet fire	2.55´10-9
		VCE	3.39´10-9
		Flash fire	1.35´10-8
Send-out piping downstream of vaporisers	Full bore rupture	Jet fire	2.80´10-7
		VCE	3.72´10-7
		Flash fire	1.49´10-6
	Leak	Jet fire	9.10´10-7
		VCE	1.21´10-6
		Flash fire	4.84´10-6
LPG Cylinder *	Rupture	Fireball	1.10´10-5
		Flash fire	1.09´10-5
	Leak	Jet fire	2.84´10-5
		Flash fire	2.85´10-5
	Escalation events	BLEVE	2.15´10-7

· * 25% of cylinders are assumed to be 13.5 kg and 75% are 49 kg (see Table 7.10). Outcome frequencies are assigned proportionally

Table 7.15: Event Outcome Frequencies for the Transit Depot

Equipment Description	Event Description	Outcome	Outcome Frequency (per year)
Road Tanker/Cylinder Wagon Transport Events
Road tanker	Rupture	Fireball	1.71´10-7
		VCE	3.98´10-8
		Flash Fire	1.59´10-7
	Large liquid leak	Jet fire	2.74´10-7
		VCE	3.66´10-7
		Flash fire	1.47´10-6
	Large vapour leak	Jet fire	3.22´10-8
		VCE	4.28´10-8
		Flash fire	1.71´10-7
	Medium liquid leak	Jet fire	1.03´10-7
		VCE	1.39´10-7
		Flash fire	5.54´10-7
	Escalation events	BLEVE	3.17´10-9
Cylinder wagons *	Rupture	Fireball	3.07´10-8
		Flash fire	3.05´10-8
Petrol tankers	Rupture	Pool fire	1.00´10-8
	Liquid leak	Pool fire	9.38´10-9
Diesel tankers	Rupture	Pool fire	6.67´10-10
	Liquid leak	Pool fire	6.25´10-10
Road Tanker/Cylinder Wagon Stationary Events
Road tanker	Rupture	Fireball	6.24´10-10
		VCE	1.46´10-10
		Flash fire	5.82´10-10
	Large liquid leak	Jet fire	1.31´10-10
		VCE	1.75´10-10
		Flash fire	6.99´10-10
	Large vapour leak	Jet fire	1.32´10-10
		VCE	1.75´10-10
		Flash fire	6.99´10-10
	Medium liquid leak	Jet fire	1.31´10-10
		VCE	1.75´10-10
		Flash fire	6.99´10-10
	Escalation events	BLEVE	2.20´10-12
Cylinder wagon *	Rupture	Fireball	1.77´10-9
		Flash fire	1.76´10-9
Cylinder wagon whilst parked overnight *	Rupture	Fireball	8.50´10-8

· * 25% of cylinders are assumed to be 13.5 kg and 75% are 49 kg (see Table 7.10). Outcome frequencies are assigned proportionally

Projectiles

Rupture of an LPG cylinder, due either to spontaneous failure or a BLEVE, may produce fragments that can cause fatal injuries hundreds of metres away. The risk associated with projectiles was further discussed in Appendix 7B. The result shows that a fragment will give a projectile fatality rate of 4.1´10^-6 per year.

7.10.8 Consequence Analysis

Consequence analysis comprises of:

¡ Source term modelling;

¡ Physical effects modelling to determine the effects zone of the various hazardous outcomes such as jet fires and fireballs; and

¡ Assessment of the impact on the exposed population.

In this study, consequence analysis is performed using the PHAST suite of models, developed by DNV.

Source Term Modelling

A source term is the information required by gas dispersion, fireball, vapour cloud explosion or other consequence models to describe the discharge rate and quantity of hazardous substance to be considered. Standard orifice type calculations are used to determine the rate of discharge, based on conditions of pressure, temperature and phase of material. Duration of discharge is determined from inventory and release rate.

LPG in Hong Kong is a mixture of 70% butane and 30% propane. Vessels are conservatively assumed to be full at time of failure; 17 tonnes for each storage vessel and 9 tonnes for an LPG road tanker.

LPG cylinders stored in the Transit Depot are refined into two groups, 25% at 49 kg and 75% at 13.5 kg. It is assumed that LPG cylinders loaded on wagons have the same size distribution.

LPG is stored in liquid form by pressurisation to moderate pressures of about 4 to 5 barg, depending on ambient temperature. A significant portion of LPG flashes upon release, forming a vapour cloud. Liquid droplets may be entrained with the vapour or rainout to the ground forming a liquid pool. In this study, pool fires were not found to be significant compared to jet fires. The more serious jet fire consequences were therefore used in the analysis.

Physical Effects Modelling

PHAST is used for the modelling of:

¡ Fireballs;

¡ BLEVEs;

¡ Jet fires;

¡ Pool fires

¡ Gas dispersion and flash fires; and

¡ Vapour cloud explosions (VCE).

Each hazard is modelled for a range of meteorological conditions to determine the size of the hazard footprint. Details are provided in Section 5 of Appendix 7B.

A summary of harm probabilities used in the current assessment is provided in Table 7.16. Persons indoors are expected to be offered some protection from fires due to shielding from the building structure; the indoor fatality is taken to be 10% that of the outdoor population. This is in line with previous studies in Hong Kong (ref. 4 & 24 for example).

Table 7.16: Summary of Harm probabilities

Consequence Event	Endpoint Criteria	Outdoor Harm Prob.	Harm Prob. Inside Buildings
Flash fire	LFL	1	0.1
Jet fire/Pool fire	Fire zone	1	0.1
	20.9 kW/m2	0.9	0.09
	14.4 kW/m2	0.5	0.05
	7.3 kW/m2	0.01	0.001
Fireball and BLEVE	Fireball radius	1	0.1
VCE	5 psi overpressure	0.09	0.55
	3 psi overpressure	0.02	0.15
	2 psi overpressure	0.005	0.035

Hazard Impact on Offsite Population

Population in the vicinity of the LPG Depot can be potentially affected by the hazardous outcomes depending on the consequence distances. Fireballs from the LPG storage vessels have a radius of up to 71 m and a lift-off height of 142 m, which covers the majority of the adjacent Preliminary Treatment Works (PTW) construction site. Fireballs and BLEVEs of LPG road tankers have a radius of up to 60 m and a lift-off height of 121 m, which can reach the nearest residential high-rise buildings (South Horizons Blocks 21 & 22). Due to the lift-off and rise of fireballs, they are assumed to affect the full height of residential blocks facing the LPG Depot. Units that are not overlooking the LPG Depot are assumed to be unaffected by fireballs. Similarly, VCE are assumed to affect only units overlooking the LPG Depot.

The maximum height of a dispersing vapour cloud was found to be 36 m. It was therefore assumed in the modelling that flash fires affect only the lowest 12 floors of residential blocks. Similarly, only 12 floors of population were taken for jet fires since radiation effects are unable to reach higher floors.

Gas Ingress into South Horizons MTR Station

The future 2031 case considers the South Horizons station during the operational phase. All parts of the station will be underground, and as such, will be unaffected by any incident at the LPG Depot. Ventilation for the station will be via vents situated on the second level of the 2-storey plant building located on Lee Nam Road at the toe of Yuk Kwai Shan. This plant building is about 200 m from the LPG Compound storage vessels and 123 m from the road tanker parking area. Vapour clouds from ruptures of these vessels/tankers can reach the plant building. The maximum vapour cloud depth at the plant building is predicted to be 8 m for a tanker rupture and 12 m for a storage vessel rupture. This compares to a vent height of about 8 m above Lee Nam Road. Ingress into the vent is therefore possible although the transit time for the vapour cloud to blow past the plant building is only 17 seconds. For such a short transit time, there is no possibility for vapours to enter the station and achieve flammable concentrations. For example, typical ventilation rates for buildings are in the range of 5 to 10 volume changes per hour. This gives a time constant for concentration changes within the station of between 1/5 to 1/10 hours (6 to 12 minutes). It is not possible for a passing gas cloud to cause significant rise in concentration within the station in just 17 seconds. No impact on South Horizons station population was therefore considered in the assessment.

Despite this, as an additional safeguard it is recommended to install gas detectors in the HVAC air intakes for the plant building that close the dampers in case of gas detection. Usually, three such gas detectors are provided with two-out-of-three voting logic to improve the reliability of the system.

A summary of consequence results is provided in Appendix 7B (Table 5.2).

7.10.9 Risk Results

Risk summation combines the estimates of the consequences of an event with the event frequencies to give an estimate of the resulting risk of fatalities. The Consultants in-house software RISKPLOT^TM has been used for risk summation to calculate the number of fatalities from each hazardous event with a given probability of occurrence. The number of fatalities is based upon the proportion of each population area overlapped by the hazard effect. Two types of risk measures are considered: societal risk and individual risk.

Societal Risk

Societal risk is defined as the risk to a group of people due to all hazards arising from a hazardous installation or activity. The simplest measure of societal risk is the Rate of Death or Potential Loss of Life (PLL), which is equivalent to the predicted number of fatalities per year. The frequency (f) and fatalities (N) associated with each hazardous outcome event are derived and the Potential Loss of Life is then calculated as follows:

PLL = f1N1 + f2N2 + f3N3 +…+ fnNn

Societal risk can also be expressed in the form of an F-N curve, which represents the cumulative frequency (F) of all event outcomes leading to N or more fatalities. This representation of societal risk highlights the potential for accidents involving large numbers of fatalities.

The PLL results for the PHI Hazard Assessment for the existing, construction and future phases of the SIL(E) project are presented in Table 7.17. The highest risks are associated with the construction phase (Year 2014) due to the additional worker population. The PLL for this year amounts to 3.39 ´ 10^-5 per year, or equivalently, one fatality every 30,000 years.

The results for the future Year 2031 case show marginally higher risk (PLL) than the existing case (Year 2009), in line with the general growth in residential population assumed in the analysis. This increase is not due to MTR operations however, since all station population will be below ground and unaffected by any incidents at the LPG Depot.

Table 7.17: Potential Loss of Life

Project Phase	PLL (per year)
Project Phase	LPG compound	LPG transit	Overall
Existing risk (2009)	5.96´10^-6	1.25´10^-5	1.84´10^-5
Construction phase (2014)	1.99´10^-5	1.41´10^-5	3.39´10^-5
Future operational phase (2031)	6.38´10^-6	1.55´10^-5	2.19´10^-5

A breakdown of PLL by population group for the construction year 2014 shows that a major component of the societal risk arises from the PTW construction workers. This is due to the close proximity of these workers with the LPG Compound. The additional population injected from MTR workers contribute only 1% to the societal risk since they are located further from the LPG Depot. This is a negligible increase in risk.

FN curves for the LPG Depot are shown in Figure 7.11. The risks for the current year (Year 2009), construction phase (Year 2014) and future operational phase (Year 2031) all lie in the acceptable region. It may be noted that the curves are in good agreement with the previous HATS study (ref. 19).

Comparing the existing risk (Year 2009) with the future operational phase (Year 2031), it can be seen that the societal risk increase slightly. This is due to the general increase in population in the surrounding area, modelled as a 1% increase per year. The population within South Horizons station does not contribute to this increase since the population is underground and will not be impacted by incidents at the LPG Depot.

The highest risk is again observed during the construction phase (Year 2014), due to the additional outdoor population on work sites. A breakdown of risks by population group for the construction phase is shown in Figure 7.12. It can be seen that the increase is predominantly due to workers at the Preliminary Treatment Works (PTW) which is immediately adjacent to the LPG Compound site. Risks to MTR construction workers are very much smaller and make negligible contribution to the overall societal risks. Details of the results are presented in Appendix 7B.

Figure 7.11 FN Curves for Current Year, Construction Phase and Future Operational Phase of the SIL(E) Project

Figure 7.12 FN Curves showing Construction Phase (Year 2014) Risk Breakdown by Population Type

Individual Risk

Individual Risk may be defined as the frequency of fatality per individual per year due to the realisation of specified hazards. Individual Risk may be derived for a hypothetical individual present at a location 100% of time or a named individual considering the probability of his presence etc. (the latter case is known as Personal Individual Risk).

Individual risk contours for the LPG Depot are presented in Figure 7.13. The 1´10^-5 per year risk contour lies inside the depot boundary and therefore meets the Hong Kong risk criterion for individual risk.

It may be noted that individual risk, unlike societal risk, is a property of the LPG Depot alone and is unaffected by surrounding population. As such, individual risk is unchanged by any changes in population that may arise from the project.

The highest individual risk occurs in the Storage Shed area due to the large number of cylinders stored there. However, incidents involving LPG cylinders have only short range effects and the risks diminish quickly away from the Storage Shed. The risks at greater distances from the facility are caused by flash fires from releases from larger inventories such as road tankers and storage vessels.

Figure 7.13 IR Contours for the LPG Depot

7.11 Conclusions

A QRA has been carried out to assess the hazard to life issues arising from the storage and transport of explosives during the construction of the SIL(E) Project.

The criterion of Annex 4 of the EIAO-TM for Individual Risk is met with regards to the hazards to life posed by the storage and transport of explosives. The assessment results show that the societal risk lies within the ALARP region when compared to the criteria stipulated in the EIAO-TM. A detailed ALARP assessment has been undertaken considering a wide range of mitigation measures and the results show compliance with the ALARP principles provided that the following recommendations are followed.

A QRA was also conducted on Shell’s LPG Depot in Ap Lei Chau to assess the increase in societal risk from the SIL(E) construction and operation. The methodology adopted followed closely that of an earlier study conducted for the same facility as part of the Harbour Area Treatment Scheme (HATS) assessment. The results obtained are closely consistent with those obtained from the previous study.

The criterion of Annex 4 of the EIAO-TM for Societal Risk is met with regards to the hazards to life posed by the Shell LPG Transit Depot/Bulk Domestic Supply at Lee Nam Road (the LPG Depot) during both construction and operational phases of the Project.

Societal risks are highest during the construction phase which overlaps with construction for the Preliminary Treatment Works which is immediately adjacent to the LPG Depot.

The South Horizons station, once completed, is also expected to make negligible contribution to societal risks since the station population will be below ground and will be unaffected by possible incidents at the LPG Depot.

Assessment of large gas releases from road tanker or storage tank ruptures suggest that it is not possible for flammable gas to ingress into the South Horizons Station through vent ducts in significant quantities.

7.1 Recommendations

Following the ALARP principles, the following recommendations are justified and should be implemented to meet the EIAO-TM requirements:

¡ The truck design should be improved to reduce the amount of combustibles in the cabin. The fuel carried in the fuel tank should also be minimised to reduce the duration of any fire;

¡ The explosive truck accident frequency should be minimized by implementing a dedicated training programme for both the driver and his attendants, including regular briefing sessions, implementation of a defensive driving attitude. In addition, drivers should be selected based on good safety record, and medical checks;

¡ The contractor should as far as practicable combine the explosive deliveries for a given work area;

¡ Only the required quantity of explosives for a particular blast should be transported to avoid the return of unused explosives to the magazine.

¡ Whenever practicable, a minimum headway between two consecutive truck convoys of 10 min is recommended;

¡ The explosive truck fire involvement frequency should be minimized by implementing a better emergency response and training to make sure the adequate fire extinguishers are used and attempt is made to evacuate the area of the incident or securing the explosive load if possible. All explosive vehicles should also be equipped with bigger capacity AFFF-type extinguishers; and

¡ Pending approval from the Commissioner of Mines Division, the licensing limit of contractors’ explosives delivery truck may be increased to minimize the total number of explosives deliveries during the construction period. Where the explosives load is higher than the 200 kg limit per truck, a higher load up to 250 kg per truck may be permitted to be transported. This will reduce the number of additional deliveries while at the same time not cause any significant increase in the consequences due to the higher load.

General Recommendations

Blasting activities including storage and transport of explosives should be supervised and audited by competent site staff to ensure strict compliance with the blasting permit conditions. The following general recommendation should also be considered for the storage and transport of explosives:

¡ The security plan should address different alert security level to reduce opportunity for arson / deliberate initiation of explosives. The corresponding security procedure should be implemented with respect to prevailing security alert status announced by the Government.

¡ Emergency plan (i.e. magazine operational manual) shall be developed to address uncontrolled fire in magazine area and transport. The case of fire near an explosive carrying truck in jammed traffic should also be covered. Drill of the emergency plan should be carried out at regular intervals.

¡ Adverse weather working guideline should be developed to clearly define procedure for transport explosives during thunderstorm.

Storage of Explosives in Magazine Store

The magazine should be designed, operated and maintained in accordance with Mines Division guidelines and appropriate industry best practice. In addition, the following recommendations should be implemented:

¡ A suitable work control system should be introduced, such as an operational manual including Permit-to-Work system, to ensure that work activities undertaken during the operation of the magazine are properly controlled.

¡ There should be good house-keeping within the magazine to ensure that combustible materials are not allowed to accumulate.

¡ The magazine shall be without open drains, traps, pits or pockets into which any molten ammonium nitrate could flow and be confined in the event of a fire.

¡ The magazine building shall be regularly checked for water seepage through the roof, walls or floor.

¡ Caked explosives shall be disposed of in an appropriate manner.

¡ Delivery vehicles shall not be permitted to remain within the secured fenced off magazine store area.

¡ Good housekeeping outside the magazine stores to be followed to ensure combustibles (including vegetation) are removed.

¡ A speed limit within the magazine area should be enforced to reduce the risk of a vehicle impact or incident within the magazine area.

¡ Traffic Management should be implemented within the magazine site, to ensure that no more than 1 vehicle will be loaded at any time, in order to avoid accidents involving multiple vehicles within the site boundary. Based on the construction programme, considering that 6 trucks could be loaded over a peak 2 hour period, this is considered feasible.

¡ The design of the fill slope close to the magazine site should consider potential washout failures and incorporate engineering measures to prevent a washout causing damage to the magazine stores.

Transport of Explosives

General Recommendations:

The following measures should be considered for safe transport of explosives:

¡ Detonators shall not be transported in the same vehicle with other Class 1 explosives. Separation of vehicles should be maintained during the whole trip.

¡ Location for stopping and unloading from truck to be provided as close as possible to shaft, free from dropped loads, hot work, etc. during time of unloading.

¡ Develop procedure to ensure that parking space on the site is available for the explosive truck. Confirmation of parking space should be communicated to truck drivers before delivery. If parking space on site cannot be secure, delivery should not commence.

¡ During transport of the explosives within the tunnel, hot work or other activities should not be permitted in the vicinity of the explosives offloading or charging activities.

¡ Ensure lining is provided within the transportation box on the vehicle and in good condition before transportation.

¡ Ensure that packaging of detonators remains intact until handed over at blasting site.

¡ Emergency plan to include activation of fuel and battery isolation switches on vehicle when fire breaks out to prevent fire spreading and reducing likelihood of prolonged fire leading to explosion.

¡ Use only experienced driver(s) with good safety record.

¡ Ensure that cartridged emulsion packages are damage free before every trip.

¡ Contractor to ensure that any electro-explosive devices are sufficiently shielded from radio frequency radiation hazards.

Contractors Licensed Vehicle Recommended Safety Requirements:

¡ Battery isolation switch;

¡ Front mounted exhaust with spark arrestor;

¡ Fuel level should be kept as far as possible to the minimum level required for the transport of explosives;

¡ Minimum 1 x 9 kg water based AFFF fire extinguisher to be provided and minimum 1 x 9 kg dry chemical powder fire extinguisher to be provided for a typical vehicles with gross vehicle weight up to 9 tonnes. For a typical vehicle with gross vehicle weight of 9 tonnes or above, a minimum of four fire extinguishers, composing 2 x 2.5kg dry powder and 2 x 10-litre foam fire extinguishers of approved type, including certificates, to be provided and mounted as specified in Mines Division guidance note (CEDD 2, 2010);

¡ A hand-held lightning detector shall be provided in the vehicle for detection of lightning before and during loading and unloading of explosives. Should lightning signal be detected within a distance of 16km from the loading/unloading point by the hand-held detector, loading or unloading of explosives shall be ceased until lightning signal is cleared;

¡ Horizontal fire screen on cargo deck and vertical fire screen mounted at least 150mm behind the drivers cab and 100mm from the steel cargo compartment, the vertical screen shall protrude 150mm in excess of all three (3) sides of the steel cargo compartment;

¡ Cigarette lighter removed;

¡ Two (2) battery powered torches for night deliveries;

¡ Vehicles shall be brand new, dedicated explosive transport vehicles and should be maintained in good operating condition;

¡ Daily checks on tyres and vehicle integrity;

¡ Regular monthly vehicle inspections;

- Fuel system

- Exhaust system

- Brakes

- Electrics

- Battery

- Cooling system

- Engine oil leaks

¡ Vehicle log book in which monthly inspections and maintenance requirements are recorded; and

¡ Mobile telephone equipped.

Recommended Requirements for the Driver of the Explosive Vehicles:

The driver shall:

¡ be registered by the Commissioner of Mines and must be over the age of 25 years with proven accident free records and more than 7 year driving experience without suspension.

¡ hold a Driving License for the class of vehicle for at least one (1) year;

¡ adopt a safe driving practice including having attended a defensive driving course;

¡ pass a medical check and is assessed as fit to drive explosives vehicles;

¡ not be dependent on banned substances;

Some of the following requirements may also apply to the vehicle attendant(s).

¡ The driver is required to attend relevant training courses recognized by the Commissioner of Mines. The training courses should include the following major subjects, but not limited to:

- the laws and Regulations relating to the transport of explosives;

- security and safe handling during the transport of explosives;

¡ Attend training courses provided by the explosives manufacturer or distributor, covering the following:

- explosives identification;

- explosion hazards; and

- explosives sensitivity;

- the dangers which could be caused by the types of explosives;

- the packaging, labelling and characteristics of the types of explosives;

- the use of fire extinguishers and fire fighting procedures; and

- emergency response procedures in case of accidents.

The driver should additionally be responsible for the following:

¡ The driver shall have a full set of Material Safety Data Sheets ( MSDS ) for each individual explosive aboard the vehicle for the particular journey;

¡ The MSDS and Removal Permit ( where applicable ) shall be produced to any officer of the Mines Division of CEDD upon request;

¡ A card detailing emergency procedures shall be kept on board and displayed in a prominent place on the drivers door;

¡ Before leaving the magazine the driver together with and/or assisted by the shotfirer shall check the following:

- Packaging integrity and labelling;

- Check that the types and quantities of explosives loaded onto the vehicle are as stipulated in the Removal Permit(s);

- Check that the explosive load does not exceed the quantities stated in the removal permit;

- Check the condition and integrity of the cargo compartment or box;

- Check that detonators are not loaded in the explosives cargo compartment and vice versa;

- Check that the cargo is secured and cannot be damaged during the delivery;

- Ensure that the appropriate placards and a red flag are displayed before leaving the magazine;

- Be competent to operate all equipment onboard the vehicle including fire extinguishers and the vehicle emergency cut-off switches;

- Prohibit smoking when the vehicle is loaded with explosives;

- When explosives are loaded, ensure the vehicle is not left unattended;

- Be conversant with emergency response procedures.

Specific Recommended Requirements for the Explosive Vehicle Attendants:

¡ When the vehicle is loaded with explosives, it shall be attended by the driver and at least one (1) other person authorized by the Commissioner of Mines. The vehicle attendant shall:

- Be the assistant to the driver in normal working conditions and in case of any emergency

- Be conversant with the emergency response procedures

- Be competent to use the fire extinguishers and the vehicle emergency cut-off switches

¡ One of the vehicle attendant(s) should be equipped with mobile phones and the relevant MSDS and emergency response plan.

Type of Explosives & their Disposal

For explosive selection, the following should be considered

¡ Cartridged Emulsions with perchlorate formulation should be avoided;

¡ Cartridged Emulsions with high water content should be preferred.

If disposal is required for small quantities, disposal should be made in a controlled and safe manner by a Registered Shotfirer.

7.2 References

[1] MTR, Consultancy Agreement No. NEX/1039, South Island Line (East) Preliminary Design, “Working Paper on Magazine Site Options Report (April 2010), (MTR 4, 2010)

[2] ERM, Express Rail Link: Hazard to Life Assessment for the Transport and Storage of Explosives, 2009 (ESB-197/2008) (ERM, 2009)

[3] HSC, Selection and Use of Explosion Effects and Consequence Models for Explosives, Advisory Committee on Dangerous Substances, 2000 (ESTC, 2000)

[4] ERM, West Island Line: Hazard to Life Assessment for the Transport Storage and Use of Explosives, 2008 (EIA153/2008) (ERM, 2008)

[5] DNV, The Risk Assessment of the Transport of Explosives in Hong Kong QRA Report, Environmental Protection Department Hong Kong Government, 1997, EPD CE63/94 (DNV, 1997)

[6] United Nations, Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria, 4th Revised Edition, 2003 (TDG-Test Manual, 2003)

[7] United Nations, Recommendations on the Transport of Dangerous Goods – Model Regulations, 15th Revised Edition, 2007 (TDG-Model Regulation, 2007)

[8] CEDD, Guidance Note on Requirements for Approval of an Explosives Delivery Vehicle, http://www.cedd.gov.hk/eng/services/mines_quarries/doc/gn_03_edv.pdf (CEDD 2)

[9] CEDD, How to apply for a Mode A Explosives Store Licence, http://www.cedd.gov.hk/eng/services/mines_quarries/doc/mode_a_store.pdf (CEDD 3)

[10] Lands Department, Geographic Information System (GIS) database, http://www.landsd.gov.hk/mapping/en/digital_map/mapprod.htm The latest information on the GIS map of buildings from the Lands Department used in this study comes from 2005 (LD, 2005)

[11] Transport Department, Annual Traffic Census 2007 (ATC, 2007)

[12] Transport Department, "Road Traffic Accident Statistics”, Government of Hong Kong S.A.R, 2007 (and previous years) (TD, 2007a)

[13] Transport Department, Road Traffic Accidents at Junction by Junction Type, Junction Control and Severity 2007, http://www.td.gov.hk/FileManager/EN/Content_1943/07fig2.12e.pdf (TD, 2007b)

[14] UK Health and Safety Executive (UK HSE)’s Explosives Incidents Database Advisory Service (EIDAS)

[15] Incident database retrieved from US Mine Safety and Health Administration (MHSA)

[16] DOCEP, Incident Log Reports retrieved from http://www.docep.wa.gov.au/resourcesSafety/Content/Dangerous_Goods/Incident_log_reports/index.htm (DOCEP)

[17] ACDS, Risk from Handling Explosives in Ports, HSC Advisory Committee on Dangerous Substances, HMSO, UK, 1995 (ACDS, 1995)

[18] EPD, Technical Note: Cost Benefit Analysis in Hazard Assessment, Environmental Protection Department, Rev. January 1996. (EPD, 1996)

[19] ENSR, 2008, Harbour Area Treatment Scheme (HATS) – Stage 2A EIA Study – Investigation, Agreement No. CE 43/2005. (ENSR, 2008)

[20] ERM, 2003, Discovery Bay’s 4th LPG Compound: Quantitative Risk Assessment. (ERM, 2003)

[21] Maunsell Environmental Management Consultants, 2006, QRA for Tung Chung LPG and Petrol Filling Station. (Maunsell, 2006)

[22] Shell, 2009, Personal Communication. (Shell, 2009)

[23] Crossthwaite, P. J., Fitzpatrick, R. D., and Hurst, N. W., Risk assessment for the siting and developments near liquefied petroleum installations, IChemE Symposium Series No. 110, 1988. (Crossthwaite, 1988)

[24] ERM, 2006, Liquefied Natural Gas (LNG) Receiving Terminal and Associated Facilities – EIA Study (ERM, 2006)