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Advisory Council on the Environment

Permanent Aviation Fuel Facility Preliminary Results of the EIA


(ACE-EIA Paper 6/2002)
For Discussion

 

1. BACKGROUND

1.1 A Permanent Aviation Fuel Facility (PAFF) is required for the Hong Kong International Airport as the existing facility near Sha Chau is temporary and does not have sufficient capacity. Furthermore, the Airport Authority has made a commitment to provide a PAFF to meet the demand for the planning horizon for the airport (2040). When the PAFF is operational, the facility at Sha Chau will be used as an emergency backup.

1.2 The Airport Authority commissioned Mouchel Asia Limited to carry out an EIA based on an EIA Study Brief issued by the Director of Environmental Protection (DEP). The EIA will be formally submitted under the Environmental Impact Assessment Ordinance (EIAO) in April/May 2002.

1.3 Preliminary results of the EIA are now available and the purpose of this paper is to present these results.

2. PROJECT DESCRIPTION

2.1 The PAFF will consist of a tank farm located at Tuen Mun Area 38 immediately to the east of the Shui Wing Steel Mill on already reclaimed land. A two-berth jetty of about 575m will be built approximately 200m off the waterfront.. The jetty will have no physical connection to the land. Aviation fuel will be tested before being discharged from vessels and then pumped to the tank via a short length of submarine pipeline from each berth. Fuel will then be tested and stored in tanks before being delivered to the airport via twin submarine pipelines.

3. ENVIRONMENTAL IMPACTS

3.1 Environmental impacts from the project are summarised in the following sections.

Noise

3.2 The site is remote from noise sensitive receivers so there will be no adverse impacts during construction or operation. Underwater noise impact on Indo-Pacific hump-backed dolphins (Sousa chinensis)(dolphins) is an important issue and this is discussed further below.

Air Quality

3.3 There are no residential or other similar air sensitive receivers in the immediate vicinity of the Area 38 site so there will be no adverse air quality impacts during construction. The EIA has concluded that there will be no unacceptable impacts posed to workers on adjacent land areas (e.g. Shui Wing Steel Mill).

3.4 Air quality impacts during operation will be restricted to fugitive emissions. The EIA has concluded that these will not be significant.

Water Quality and Marine Ecology

3.5 These are considered together as the sources and the impacts are closely related. The impacts affect only the marine environment.

3.6 Environmental impacts with respect to the marine environment are restricted to those from the construction and operation of the pipeline and the jetty. The pipelines will be laid in a dredged trench about 3m deep with rock armour placed above the pipelines to avoid any possibility of damage from ships or anchors in the future. The jetty will be a piled structure with the jetty superstructure formed on top of the piles

3.7 Two options are being considered for the pipelines from PAFF. Option 1 has been designed to follow the same alignment as the existing access channel to the existing Aviation Fuel Receiving Facility (AFRF) at Sha Chau and it will be constructed at the same time as routine maintenance dredging for the access channel. Option 2 would follow a more circuitous and longer route direct to the airport (see Figure 1).

3.8 Characteristics of the the pipeline route options are as follows:

  Option 1 Option 2
Length 4.8km 11.2km
Dredging quantity 274,000 cu m 563,000 cu m
Construction time approx. 39 days approx. 80 days

3.9 Key sources of impact to the marine environment can be summarised as follows:

  • Dredging of the pipeline could release suspended sediment to the water column and some of this could settle on the sea bed. Investigations for the EIA have concluded that none of the sediments to be dredged are contaminated so only clean sediment will be released and the dredged material will be suitable for open sea disposal. The dredging quantities are quite small in comparison with other recent and ongoing dredging works in the same area and computer modelling has confirmed that significant impacts are not expected.
     
  • The dredging could cause physical disturbance to the dolphins in the vicinity of the works and this issue is discussed further below.
     
  • Investigations have been carried out to consider the potential for sediment deposition on the artificial reefs in the marine park. The impacts are considered not to be significant.
     
  • Spills from the pipeline. There is a very low risk of a spill due to damage to the pipeline in view of the depth of burial and the rock armour protection. Spill release scenarios have been modelled and it has been concluded that impacts will not be significant. The pipeline will shut down automatically in the event of any leak.
     
  • Spills from vessels unloading. The unloading berth is some distance from the marine park. However spills from vessels unloading could be driven by wind or currents towards the marine park and areas closer to the jetty are also dolphin
     
  • habitat. Spill management measures will be implemented which will include containment booms that will be deployed immediately there is a spill and clean up equipment will be immediately available. Similar emergency response plans and spill management plans to those used for the existing AFRF will be implemented and it is considered that the mitigation will be sufficient to reduce potential impacts to an acceptable level.
     
  • Percussive piling will be used for the jetty. Potential impact on dolphins is an important issue which is discussed further below.
Terrestrial Ecology

3.10 There are no impacts on terrestrial ecology as the site at Tuen Mun Area 38 has already been formed.

Risk Assessment

3.11 The EIA includes a risk assessment to check compliance with the Hong Kong Interim Risk Guidelines (HK IRG). This has concluded that the individual risk is within the HK IRG. The societal risk for the tank farm lies in the Acceptable region of the FN curve and the societal risk for the jetty lies partly within the ALARP region and partly within the Acceptable region.

Landscape and Visual Impacts

3.12 The closest residential visual sensitive receivers (at Butterfly Estate) are some distance away from the site of the tank farm and the site is barely visible, even from the top of the residential blocks. The setting of the site within an industrial area reduces the potential for impact.

Cultural Heritage

3.13 The cultural heritage assessment has focused on marine archaeology along the pipeline route. There are no cultural heritage impacts at the Area 38 site as it is reclaimed land. A desk study has been completed and this has concluded that the pipeline route has a high marine archaeological potential in common with other areas around Tuen Mun and northern Lantau. However, the recommended pipeline route (Option 1, see below) will involve only a limited amount of disturbance to previously undisturbed seabed as it will cross the CLP berthing-channel dredged area and will follow the already dredged access channel and turning circle of the AFRF.

3.14 The desk study has concluded that a marine archaeological site investigation should be carried out, comprising a geophysical survey followed by dive surveys if necessary to confirm the results of the geophysical survey. It has also concluded that a feasible alignment can be found and even if archaeological remains were found the alignment can be altered so that there is no impact.

3.15 It has therefore been agreed with Archaeology and Monuments Office that the site surveys should be carried out at the same time as the engineering site investigations and the EIA is recommending that the Environmental Permit should include a

requirement that the marine archaeological investigation must be completed before any construction works start.

4. PIPELINE ROUTE SELECTION

4.1 As mentioned above, two routes have been considered in the EIA. The EIA has considered these two options in detail and we are now able to make a recommendation for the preferred route on environmental grounds. This recommendation is summarised in this paper and full details will be given in the EIA Report. The assessment of the two options for the alignment of the pipeline has been made based on a review of impacts to the marine park and the dolphins as well as on other environmental criteria. The assessment of the impact on the dolphins has been carried out by Dr Tom Jefferson.

Construction Impacts

4.2 Option 1 passes through the marine park for about 400m. However it will be constructed at the same time as maintenance dredging is undertaken in the access channel/turning basin so additional impacts will be minimal as no additional seabed will be disturbed. Option 2 passes outside the marine park but will require significantly more dredging, disturbing a larger area of previously undisturbed seabed.

4.3 Dr Tom Jefferson has evaluated the predicted impact of the two pipeline options on the Hong Kong/Pearl River Estuary population of Indo-Pacific Hump-back dolphins (Sousa chinensis). He used information on dolphin density in the North Lantau area from a long-term research project (see Jefferson and Leatherwood 1997; Jefferson 2000) to make a quantitative comparison of the two options. In addition to being numerical, and thus facilitating direct comparison, this approach has the advantage of being an entirely objective assessment based on the best available scientific data.

4.4 The method of estimating the impact of the two pipeline options on the dolphin population was based on an Impact Index for each pipeline option, according to:

  • The number of 1 km2 blocks the pipeline route passes through,
  • Dolphin density in each block; and
  • The length of pipeline route in each block.
4.5 The higher the Impact Index, the higher the predicted impact on the dolphin population, based on the assumption that human activity (e.g. dredging) in a higher density area for dolphins would have a greater impact than the same activity in a lower density area. The dolphin density in each 1 km2 block was calculated by evaluating the number of on-effort (e.g., collected during strict line transect sighting effort surveys) dolphin sightings in that block, after deleting any land area. Dolphin sightings were evaluated based on the Ocean Park Conservation Foundation humpback dolphin sighting database, which covers vessel surveys conducted between November 1995 to October 2001 (see Jefferson and Leatherwood 1997; Jefferson 2000). The length of pipeline was calculated by overlaying a map showing the two pipeline routes over a 1x1 km grid of the study area.

4.6 The pipeline option directly to the airport (Option 2) passed through 16 1-km2 blocks and had an Impact Index of 86.99. The option connecting to the Sha Chau AFRF (Option 1) passed through only 7 blocks and had an Impact Index of 64.43, which is only 74.1% of the Option 2 index. This indicates that the Sha Chau option (Option 1) is likely to have a significantly lower impact on the dolphin population. Option 1 is thus recommended for the PAFF pipeline route to the airport with respect to impacts on the dolphins.

Operational Impacts

4.7 The only operational impact from the pipeline itself would arise in the event of a leak. The potential for leaks is considered to be minimal so neither pipeline option will have a significant impact.

4.8 An important aspect during operation will be the need for continued use of the AFRF for Option 2. This facility needs to be maintained as an emergency backup whichever pipeline option is used, with the existing pipeline to remain operational. In Option 1 the existing pipeline will be flushed with new fuel during every delivery from the Tuen Mun Area 38 PAFF site. However with Option 2 there will be no routine pumping of fuel through the existing pipeline. As fuel cannot be allowed to lie in the pipeline for long periods, it must be flushed on a regular basis. In Option 2, fuel barges will continue to use the existing AFRF at Sha Chau approximately once every six weeks to flush fuel through the existing pipeline and the existing potential for impacts will continue. This will not be required for Option 1 so Option 1 is preferred.

5. PIPELINE ROUTE RECOMMENDATION

5.1 Option 1 is preferred with respect to impacts on the dolphins during construction and operation and with respect to operational impacts on the marine park. Other impacts are similar for both options. Other environmental impacts are also less significant for Option 1 than Option 2.

5.2 Option 1 is therefore recommended.

6. IMPACTS FROM THE CONSTRUCTION OF THE JETTY

6.1 There is a potential for impacts on the dolphins from construction of the jetty and, while this is not in the marine park, we would like to bring members attention to the potential impact and the mitigation measures.

6.2 The jetty will have a similar form of construction to the existing AFRF at Sha Chau, although the new jetty will be designed to berth ships up to 80,000dwt. The deck will be supported on piles and these have to be driven percussively due to the depth of the water and the sea bed conditions. Percussive piling could have an impact on the dolphins' echo location systems and mitigation measures giving similar benefits to those used at the Sha Chau jetty have been considered. The area around Tuen Mun Area 38 is used extensively by the dolphins as shown by the research carried out by Dr Tom Jefferson and others.

6.3 The mitigation at the Sha Chau jetty comprised a bubble curtain and a dolphin exclusion zone. The exclusion zone can still be used at Tuen Mun Area 38 but there are difficulties in using the same form of bubble curtain due to the higher current speeds and the deeper water. An alternative form of bubble curtain is being considered for the Area 38 jetty. In this alternative design the bubbles will be encased in a large diameter tube placed around the pile with the bubble jets at the bottom.

6.4 We have held preliminary discussions with Dr Tom Jefferson on this form of mitigation and he considers that this should be investigated further. The large diameter tube to contain bubbles is now being developed for inclusion in the EIA.

7. NEXT STEPS

7.1 Members are invited to comment on:

  • the recommendation of the EIA that Option 1 for the pipeline should be adopted; and
  • the proposed mitigation for the construction of the jetty.
7.2 Members are advised that the EIA will be submitted formally to the Director of Environmental Protection as required under the EIA Ordinance in April/May 2002. A presentation of the final report will then be made.

Airport Authority Hong Kong
February 2002

 



 

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