12.               HAZARD TO LIFE

Introduction

12.1            According to the EIA Study Brief, a hazard assessment following the criteria for evaluating hazard to life as stated in Annexes 4 and 22 of the EIAO TM shall be conducted if there is to be overnight storage of explosives on-site, which could increase the level of risk to populated areas.  Explosives are required for both the excavation of the summit (including a tunnel to the proposed glory hole) and excavation of the tunnel required for the funicular system and will be using the drill and blast method.  The explosives would be delivered from the Government explosives magazine on Lantau to the Ocean Park site and there is a need to store a limited quantity of explosive and flammable materials at the Ocean Park site.  Thus, a hazard assessment for explosives storage and handling was carried out and is presented in Appendix 12.1.

 

Environmental Legislations, Policies, Plans, Standards and Criteria

12.2            As set out in Annex 4 of the EIAO TM, the risk guidelines comprise two components: 

 

·         Individual Risk Guideline: the maximum level of off-site individual risk should not exceed 1 in 100,000 per year, i.e. 1 x 10-5 / year;

·         Societal Risk Guidelines: the Societal Risk Guideline is expressed in terms of lines plotting the frequency (F) of N or more deaths in the population from accidents at the facility of concern.  There are three areas shown:

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

-         Unacceptable where risks are so high that they should usually be reduced regardless of the cost or else the hazardous activity should not proceed; and

-         ALARP (As Low As Reasonably Practicable) where the risks associated with the hazardous activity should be reduced to a level “as low as reasonably practicable”, whereby the priority of measures to be adopted is established on the basis of practicability and cost to implement versus risk reduction achieved.

 

Assessment Approach and Methodology

12.3            The approach and methodology adopted for the Hazard to Life Assessment includes the following key elements:

 

§         Identification of all credible and applicable hazardous scenarios associated with the storage, transport and use of explosives for blasting operations.  A review of previous incidents involving explosives has been undertaken to identify the hazardous scenarios for the QRA.

§         Execution of a Quantitative Risk Assessment (QRA), which takes into account the identified safeguards and recommendations as assumptions to form the basis for the “Base Case”, to express population risks in both individual and societal terms; 

§         Comparison of the estimated individual and societal risk levels with the Criteria for Evaluating Hazard to Life stipulated in Annex 4 of the EIAO TM; and

§         Identification and assessment of practicable and cost-effective risk mitigation measures where necessary.

 

Assessment Result

Base Case

12.4            A revised Base Case has been defined which has an acceptable risk to life.  The following detailed provisions have been defined:

 

·        The explosives magazine will be located adjacent to a service road off Nam Long Shan Road.

·        The location is shielded by natural slopes to the north, east and south.

·        There will be two separate magazines - one for detonators and a second for high explosives; 

·        The magazines and the magazine compound will be designed to the requirements and standards set down by the relevant authorities; 

·        These provisions will include security services operational 24 hours a day and 7 days per week; 

·        Mines Division of CEDD will deliver all explosives to be used at the Site directly to and unload the explosives into the magazines on a daily basis.  This delivery will take place at noon or early in the afternoon; 

·        The section of Nam Long Shan Road, leading to the service road to the explosives magazine, is within Ocean Park.  The existing Ocean Park security control at Nam Long Shan Road will be relocated to the west to encompass the explosives magazine as well as a proposed storage facility for emulsion matrix; 

·        Daily loading and transport of explosives to the blasting sites shall take place immediately after sunrise (6:00 to 7:00 am depending on time of year) for charging and blasting of explosives by 9:00 am before Ocean Park opens to the public; 

·        There will be no off-site delivery of emulsion matrix to the north portal of the funicular system.  Emulsion matrix will be delivered directly to the north portal of the funicular system by the supplier of the bulk emulsion; 

·        All charging and blasting of explosives will take place before Ocean Park opens to the public; and

·        Surface blasting will be subject to additional controls on the movement of persons within Ocean Park.   

 

12.5            Blasting Operations at the north portal of the funicular system will require delivery of explosives outside the Site since Ocean Park comprises two separate areas connected only by the cable car or by public streets (Shum Wan Road, Nam Long Shan Road and Ocean Park Road.  The Assessment has included the daily transport of the explosives from the on-site magazine to the blasting site at the north portal of the funicular tunnel. 

 

12.6            Daily delivery of explosives to the north portal would be carried out by the Contractor’s licensed shot firer and using the Contractor’s approved explosives delivery vehicles and will be subject to any additional controls stipulated by the relevant authorities.  It is envisaged that this transport will be carried out between 5:00 and 6:00 am when traffic on public roads will be minimal, and that each vehicle will be escorted by armed security guards in a separate vehicle.  Transport of explosives will involve at least two separate trips (one for detonators and one for other explosives) and that the volume of explosives will be limited to 25 kilograms or less each trip.  The volume of explosives required for the initial length of tunnel (usually set at 50 metres) will be substantially reduced for the subsequent sections as it would then make use of emulsion matrix (not classified as an explosive) in lieu of the packaged emulsion (classified as an explosive).

 

12.7            Differentiating aspects of this Base Case over the original Base Case are:

 

·        Mines Division will deliver all explosives directly to the explosives magazine by road transport and will not utilise marine transport or the proposed marine barging point;

·        Reduction in the diameter of individual blast holes and the amount of explosives used for each blast; and

·        There will be no on site storage of ammonium nitrate, fuel oil or ANFO.  The blasting operations will utilise emulsion matrix and the on-site storage will be provided in accordance with the requirements to be laid down by Fire Services Department. 

 

Individual Risk Results

 

12.8            The 1 x 10-5 / year individual risk contours for explosives storage extend up to 100 m radius.  For delivery routes, there is no area with individual risk contour higher than 1 x 10-5 / year.  The risk level of 1 x 10-9 / year extends to 7m along the delivery route, measured from the vehicle.  Within the Park, there will be no members of the public along the delivery routes at the time of deliveries, since the road will be closed to the public.  This condition shall not apply for deliveries to the north portal of the funicular. 

 

12.9            The area of highest risk is around the magazines where the level of risk exceeds 10-5 per year.  The area is centred around the Emulsion Matrix storage with a radius of 100m.  The magazines are sited in an area that is remote and since the Park is closed there will be no members of the public at the magazine site which will be secured 24 hours per day, 7 days per week.

 

Societal Risk Results

 

12.10        For societal risk, an F-N curve is included in Appendix 12.1.  The curve lies completely within the “Acceptable” region.  The potential loss of life (PLL) for the residual risk from the explosives storage, handling and transport is 1.3 x 10-7 / year.

 

Conclusions and Recommendations

12.11        A QRA study for the explosives related activities for the Project has been carried out.  Systematic hazard identification workshops have been conducted for both an original Base Case and a revised Base Case and a large number of routine or otherwise practicable safeguards and recommendations have been identified.  The risk level for the original Base Case was found to be unacceptable and therefore a new blasting strategy has been developed in consultation with Mines Division of CEDD.  A number of additional risk control measures were identified and were included in this revised Base Case.  For the revised Base Case, the level of offsite societal risk is within the acceptable limit, and since no area of individual risk greater than 10-5 per year could affect the public, therefore the risk level of the revised Base Case is considered acceptable.  

 

12.12        In the case of the transport of explosives to the north portal of the funicular system, an assessment is also included in the QRA based on the specific controls set down for this transport for separate consideration by the relevant authorities.  The associated level of risk is within the acceptable range.  In the event that this transport is not agreed, it will not be undertaken.  Consideration of this activity should therefore be considered as distinct from the proposed on site storage of explosives and transport of the explosives to other blast sites that do not require off-site transport. 

 

12.13        A list of safeguards and recommendation identified in the systematic hazard identification workshop are presented in Appendix 12.1. 

 

12.14        To ensure that the assumptions (S.12.4 and S.12.7) and recommendations from the Quantitative Risk Assessment (QRA) study and the safeguards and recommendations (Appendix 12.1 – S.3.4.2 and Appendix 12.1 – S.6.5) from the systematic hazard identification are consistently implemented in accordance with the intent of the hazard to life assessment, the blasting activities should be inspected and audited at practical intervals to ensure that the assumptions and recommendations from the Quantitative Risk Assessment (QRA) study and the safeguards and recommendations from the systematic hazard identification are consistently implemented in accordance with the intent of the hazard to life assessment.