13.1
Relevant Environmental Legislation
13.1.1
EPD ProPECC Note No. 3/94
13.1.1.1 The Practice Note for Professional Persons issued by the Environmental Protection Department on Contaminated Land Assessment and Remediation advises that Environmental Impact Assessment reports for new industrial developments including oil depots should :
¨ identify possible sources of contamination; and
¨ formulate appropriate operational practices, waste management strategies and precautionary measures for the prevention of contamination problems.
13.1.1.2 It further advises that measures for the contamination of land contamination problems are relatively simple, mainly relying on good engineering practice, well developed waste management strategies and established industrial guidelines.
13.1.2
Hong Kong Code of Practice
for Oil Storage Installations, 1992
13.1.2.1 The Hong Kong Code of Practice for Oil Storage Installations, 1992
issued by the Building Authority sets down the requirements for the design,
construction and maintenance of oil storage installations in Hong Kong so as to
reduce the risk of environmental pollution. It deals with key design features such as foundations,
containment bunds, tanks and drainage.
In addition it addresses inspection and repair requirements and
provisions for contingency planning to deal with spillage and other
environmental pollution incidents.
13.2
Description of Existing Conditions
13.2.1
The PAFF site at Tuen Mun Area 38
currently comprises undeveloped recently reclaimed land with was produced using
public fill material. The site currently used for stockpiling of inert public
fill material only. Thus, there is no reason to believe that the land is in any
way contaminated at present.
13.3.1 No contaminated ground should be exposed or excavated during construction of the project and thus, the key issue with regard to land contamination is to ensure that construction works or the operation of the facility at the site will not cause any land contamination in the future.
13.3.2 The PAFF site will ultimately provide for the storage of about 420,000m3 of aviation fuel. Leakage or spillage of this material could result in serious contamination of the underlying ground and possibly seepage to sea, where it could pollute the coastal environment. It is therefore essential to ensure that the fuel storage facilities are secure, provided with robust leakage detection systems and that effective spill control measures are implemented.
13.3.3 There will be no direct discharge of any wastewater anywhere on site. However, uncontrolled polluted surface drainage from the site roads and workshops also has the potential to contaminate the ground. These risks are relatively minor in comparison to the risk of bulk fuel spills and leaks and can easily be minimised by appropriate design of the storm water system.
13.3.4 No other chemicals will be held on site in any significant quantity except for oil dispersants and fire-fighting foam.
13.4.1 Pollution from surface drainage from the site roads and workshops can be controlled by the drainage from all areas of hardstanding, including fuel storage and handling facilities, areas of vehicular traffic, sites used for vehicle or plant maintenance or adjacent to covered workshops being diverted through an oil/water interceptor prior to discharge. In order to reduce the amount of runoff to be treated, uncontaminated runoff such as from the building roof and landscaped areas should be collected separately and discharges to the storm water drain.
13.4.2 However, spills and leaks from storage tanks and pipework pose the principal potential contamination threat to the ground. All storage areas will be bunded to 110% of the capacity of the largest tank in the bund and this provides the principal mitigation against sizeable spills. Fuel oil losses to the surface of the facility outside the bunded area would be contained in the first instance by the stormwater drainage system providing the opportunity for clean up before any seepage into the underlying ground occurs.
13.4.3
Leakage from the bunded area could
only occur following primary failure of tanks or pipework within the bund
coupled with a secondary failure or overtopping of the bund wall or liner
system. Possible sources of
contamination can be identified as follows :
¨ failure of tank walls;
¨ failure of pipelines;
¨ leaking pipejoints;
¨ failed seals within gaskets, pumps or valves;
¨ overfilling; and
¨ leakage from sampling points.
13.4.4
Prevention of losses from these
sources will principally be addressed by design and adherence to international
standards in the plant specification.
Once commissioned all storage facilities will require to be subjected to
a regular inspection and maintenance programme. The risk of spills and leaks from these sources has been
examined in Section 10 and found to be very low (see Section 10.5).
13.4.1 To prevent seepage of lost fuel into the ground it is essential that any leaks are promptly identified and cleaned up. With such measures in place no significant contamination of the underlying ground would be expected even in the event of a spillage. Recommended mitigatory measures to this effect are identified in the following section.
13.5.1 The implementation of appropriate mitigation for the oil storage facilities and pipework is required to ensure that risk of ground contamination as a result of oil spills or leaks is kept to a practical minimum. Such measures should include the following. These measures are also summarised in the Environmental Mitigation Implementation Schedule in Appendix B:
¨ bunding of all fuel storage areas;
¨ adherence to relevant design standards for storage tanks, pipework, containment and drainage;
¨ regular plant inspections and maintenance;
¨ impermeable lining of tank pits;
¨ leak detection systems;
¨ controlled surface drainage and the provision of emergency shut off valves;
¨ emergency spill response plans; and
¨ provision of spill control materials and equipment on site.
13.5.2
Key mitigation recommendations for the
bunded containment have been identified in Section 6.7. The most important features are that
all tanks shall be bunded to a capacity of at least 110% of the largest
individual tank in each compound.
Tank pits shall be protected by an impermeable bed (e.g. geotextile
sheeting, bitumen lining) to prevent seepage of oil to ground and a leak
detection system shall be installed beneath the containment membrane. A concept design for a tank
incorporating these features is provided in Figure 13.1.
13.5.3 The facility operator shall be required to draw up detailed contingency plans based upon an approach of prevention and detection in the first instance and to ensure containment and safe disposal if any fuel is lost from tanks or pipework. The Emergency Response Plan for the PAFF will be developed for the approval of the Authorities. The rationale for the plan is detailed in Table 13.1 below:
Table 13.1 Spill
Management Plan Rationale
|
Operation |
Approach |
Method |
Monitoring |
|
Oil
Leaks/ Spills |
Prevention Detection |
Established practices & operator
training |
Regular ground water assessment through
selected bore holes |
|
Pipelines |
Early detection and isolation |
Automatic shut down |
Pressure of line Frequency and duration of pumping |
|
Tankage |
Early detection |
Removal from service |
Under tank hydrocarbon monitors |
|
Prevention |
Containment bunds |
|
|
|
|
|
|
|
|
Transfer operations |
Prevention |
High level liquid shutoffs |
Visual inspections |
|
Oil
Spills Response |
Containment and disposal |
Response team training and pre-positioned
equipment |
Visual inspections |
13.5.4 The key features which should be included in the plan are summarised below:
¨ organisation of the oil spill response team and the responsibilities of each member. Suitable and regular oil spill response training should be provided to the operating personnel and regular oil spill response drills be conducted to test and exercise the responses;
¨ response strategies/procedures to be adopted in the case of an oil spill, including:
- reporting to relevant Authorities;
- identification of the source of spill;
- containment of leaking fuel;
- recovery and processing of free fuel;
- clean up methodology; and
- handling and disposal protocols.
¨ risk assessments to identify the maximum credible spill scenario for PAFF and other operational spill scenarios and the fate of a fuel spill;
¨ set up of emergency centre in PAFF;
¨ communication means during oil spill and 24-hours emergency contact list;
¨ training and competence level requirement of PAFF staff;
¨ oil spill equipment required;
¨ sub-contracting services;
¨ drills and exercise requirements; and
¨
follow-up procedures.
13.5.5
Other key mitigation measures for the
protection against contaminated land include the following:
¨ run off from the roofs of site buildings and landscaped areas shall be conveyed in closed drains to the nearest storm water drain to prevent the generation of excessive quantities of surface water which may be polluted;
¨ suitable absorbent materials (e.g. sand or earth) shall be kept on site to deal with spills. Chemical dispersants shall not be employed;
¨ the facility shall be designed, constructed, operated and maintained in full accordance with the Code of Practice for Oil Installations, 1992;
¨ tank pressure testing shall be carried out routinely to check for possible tank leaks. Product inventory monitoring shall be integrated into site management procedures to check for any abnormal or unexpected product loss;
¨ tank overfill monitoring systems shall be installed and regularly tested. Inlet valves should automatically shutdown on exceedance of “high-high level” to prevent over-filling;
¨
pipe leakages shall be routinely
checked for by means of a pressure sensitive leak detection system and routine
inventory control;
¨ drainage from areas of hardstanding shall be treated by means of oil / water separators prior to discharge to storm drain. All surface drainage shall be fitted with closure valves to provided additional containment and facilitate clean up of any leaks; and
¨ it is recommended that the delivery pipeline from the jetty and the supply line to the airport shall be fitted with pressure sensitive leak detectors.
13.6.1 With the recommended mitigatory measures in place to prevent, contain and clean-up spills and leaks of fuel oil stored or conveyed to and from the site, no ground contamination of environmental concern would be expected to arise and no adverse residual impacts are predicted.
13.7
Environmental Monitoring and Audit
13.7.1 Based upon the integrated mitigation measures and procedures which will be put in place to prevent, contain, clean-up and dispose of any spillage, significant environmental effects are highly unlikely to arise. The regular programme of inspections of the system during the operational stage will be specified in the emergency response plan. However, design phase audit of the spill response plan to ensure it includes the necessary elements and of the design of the pipelines, tanks and jetty to ensure key spill detection and control elements are included is recommended. Further details are provided in Section 15 of this report and in the EM&A Manual