2 CONSIDERATION OF ALTERNATIVES
2.1 Consideration of Alternative Site
Locations for the PAFF
2.1.1.1
2.1.1.2 To overcome this, and to mitigate the effect of delay in the construction of the PAFF, the AAHK has upgraded the current aviation fuel emergency connection at the West Quay on the airport which can receive aviation fuel and has a throughput capacity of about 1.1 billion litres per annum. The operational throughput capacity of the AFRF plus the throughput capacity of West Quay, is in total around 6.2 billion litres per annum. However, even with the use of West Quay (which is only a contingency measure), the projected demand of aviation fuel will exceed this combined operational throughput capacity of AFRF and West Quay in 2007. If AFRF is allowed to work above the operational throughput capacity in case there are no typhoons T3 signal and above, the sustained throughput capacity of AFRF plus the throughput capacity of West Quay would be able to support the demand of aviation fuel to around 2009.
2.1.1.3
Under the Gazette Notice 1294 of 13 April 1995, the
AFRF at Sha Chau must revert to an emergency back-up as soon as the permanent
facility has been expedited.
Accordingly, expansion of the AFRF at Sha Chau is ruled out and is, in
any case, impracticable on the basis of the shallow water around Sha Chau and
its location within the
¨
a jetty;
¨
a tank farm; and
¨
sub-sea pipelines.
2.1.1.4 The PAFF facility will be designed in accordance with the latest technology, standards and statutory requirements as detailed in Section 3 and Appendix A00. In order to provide the projected ultimate throughput capacity, the following requirements must be met:
Fundamental Requirements of the Jetty
(i) two berths are necessary to provide the ultimate discharge capacity, given that:
¨
the average parcel size would be about 35,000m3;
¨
discharge of this parcel size takes about 24 hours;
¨
berth occupancy must allow for down time, poor visibility, tidal
windows, waiting on vessel to arrive, etc; and
¨
replenishment of stocks is required following drawdown during typhoons.
(ii) a range of vessel sizes must be accommodated because, given the trend towards larger vessel utilization and advice from the industry that a maximum vessel size of 80,000 dwt must be accommodated, the berths must make allowance for a range of vessel sizes from 10,000 to 80,000 dwt. (Currently, 80,000 dwt dedicated vessels provide aviation fuel to some airports in Europe and this trend is expected to grow elsewhere in the world including Asia). This will require a jetty, with two berths end to end, of about 575 metres length.
Fundamental
Requirements of the Tank Farm
(i) Quality of the fuel supplied to the airport must be maintained to the highest standards. Settlement, cleaning and drying of the fuel, once discharged from ocean going tankers, must be carried out to international standards. Maintaining a high quality of fuel using these methods has implications on the number of tanks required at the tank farm as follows: -
a) initial phase (2009) - based on the logistics below, it was determined that eight tanks are required:
¨
two large vessels (say 35,000m3 parcels each) could be
discharged simultaneously to two to three tanks, for quality control;
¨
previously discharged fuel will occupy at least two to three tanks
during quality control, prior to release as hydrant ready fuel
¨
two tanks are required for pumping to the airport; and
¨
one tank could be under maintenance;
b) ultimate phase (2040) - based on the logistics below, it was determined that twelve tanks are required.
¨
two large vessels (say 80,000m3 and 40,000m3 parcels respectively)
could be discharged simultaneously to five tanks for quality control;
¨
previously discharged fuel will occupy at least three to four further
tanks during quality control, prior to release as hydrant ready fuel;
¨
four tanks would be required for pumping to the airport; and
¨
one tank may be under maintenance.
(ii) In addition, the operation, maintenance, security, safety and routine activities at the PAFF tank farm are catered for by provision of an office with associated facilities (e.g. car park, Emergency Vehicle Access, boundary fence, landscaping etc).
Fundamental
Requirements of the Pipeline
(i) To provide the necessary throughput rate and security of supply, twin subsea pipelines of 500mm dia (identical to those from the existing AFRF at Sha Chau to the airport) are required.
2.1.1.5 It is imperative that fuel quality is not compromised as safety of airport operations is of paramount importance. In order to maintain fuel quality and safety, the tank farm must be adjacent to the jetty for the following reasons:
¨
Industry practice dictates that tank farms should be located adjacent
to the jetty. The Airport Authority
respects the wisdom of industry practice and does not contemplate adopting
inferior practices.
¨
The longer length of pipeline required when the tank farm and jetty are
separated, will, in turn, increase the risk of static electricity build up
within the fuel, with an increased risk of ignition upon entry of the fuel to
the tanks. To avoid this on longer
pipelines, a Static Dissipator Additive (SDA) is dosed into the fuel, but the
rate of doping is sensitive (under/over doping are both undesirable). It is thus very difficult to inject the
correct dose accurately into a flowing pipeline at the jetty.
¨
Water is often present in the compartments of ocean going tankers,
sometimes in considerable quantities.
When this fuel/water interface reaches the equipment, a shock or “water
hammer” effect occurs in the system.
This affects the filter/water separators with a resulting increased risk
of damage and an associated increased potential for fuel spills.
¨
Despite best efforts to eliminate water from the pipeline by use of
filter/water separators, some water will inevitably enter the pipeline. Accordingly, the risk of corrosion (and thus
leakage) from the pipeline is greater.
¨
There is occasionally a need to remove off-spec fuel from the
PAFF. A longer pipeline produces a
larger quantity of off-spec fuel (through comingling with other batches). Pumping the off-spec fuel back to a tanker at
the jetty also produces further off-spec fuel (by subsequent additional
comingling) and requires a greater volume of good fuel to purge the off-spec
fuel from the pipelines.
2.1.1.6 Thus, the search for a suitable site for the PAFF is based on the following criteria:
¨
marine access of at least 17m water depth to
accommodate vessels at a jetty with two dedicated berths;
¨
environmental acceptability (to the community,
ACE and Green Groups);
¨
sufficient land adjacent to the jetty to
accommodate tanks and related facilities;
¨
viable route for twin pipelines to the airport;
and
¨
timely completion.
2.1.1.7 It was determined as early as 1991 that PAFF was a fundamental requirement for delivery of aviation fuel by large vessels to the airport.
2.1.1.8
The search for a PAFF site has taken place over a
period of 10 years, during which environmental awareness, environmental
concern, the statutory environmental framework and the political back-drop have
changed significantly in
2.1.1.9 In 1992, the most realistic and practicable sites within HK SAR waters, following consultation with Government, were identified as:
(i)
Airport;
(ii)
Bluff Point (BP);
(iii)
East of Sokos (EOS);
(iv)
Kau Yi Chau (KYC);
(v)
Ma Wan
(vi)
Penny’s Bay;
(vii)
Sham Shui Kok (SSK);
(viii)
Sham Wat (SW);
(ix)
Tsing Yi (TY);
(x)
Tuen Mun including Tuen Mun West (TMW) and Tuen
Mun Area 38 (TMA 38);
(xi)
Mo To Chau (The Brothers);
(xii)
Lung Kwu Chau.
2.1.1.10 In 1993, Mo To Chau and Lung Kwu Chau were ruled
out from further investigation on the basis of their extreme environmental
sensitivity. Other factors against locating the PAFF on Mo To Chau
include, difficulties in aligning the jetty satisfactorily along the ebb and
flood tides, compromising the efficiency of air navigation and safety systems
and being directly under the flight path.
2.1.1.11 The results of more detailed investigations were that (i) Airport, (v) Ma Wan Island, and (vi) Penny’s Bay sites were found to be impracticable for the following reasons:
¨
Airport
-
extremely shallow water surrounding the airport would necessitate
extensive capital and maintenance dredging for a vessel access channel and a
turning basin. Such extensive dredging
would have associated potential environmental impacts.
-
statutory the airport height restrictions for
flight safety which define the maximum height of fixed or transient objects;
-
statutory marine exclusion zones which extend
some 2.5km east and west of the airport;
-
contaminated mud pits which lie to the north of
the airport; and
-
a jetty located either to the east or west of the
airport would be most prone to risks from aircraft incidents either immediately
before landing or after take-off.
¨
Ma Wan
-
Ma Wan has historically been an important fish mariculture area, lies
in an area of very fast tidal currents (which are unsuitable for siting a jetty
of the size required) and is now under development as a residential area. Thus, these uses are incompatible with
collocation of a PAFF, but also the site is fundamentally impracticable because
of the tidal currents.
¨
Penny’s Bay
-
Penny’s Bay was originally intended to be reclaimed for the
purpose of a Port/Container Terminal but subsequently has been earmarked, and
is now being developed, for Disney.
Because of incompatibility with these land uses, the site was ruled out.
2.1.1.12 In addition, sites (ii) Bluff Point and (viii) Sham Wat were also ruled out for environmental reasons, in particular because of their potential impacts on water quality and ecology.
2.1.1.13 In 1993, a hazard assessment study of the risk associated with passage of aviation fuel tankers through the Ma Wan Channel resulted in the ruling out of sites in North Lantau Waters. This study considered the long term transit of large aviation fuel vessels through the channel. It was determined, at that time, that the risk was in the ALARP region of the FN curve within HK Risk Guidelines, but could not be mitigated to as low as reasonably practicable. Thus it would not be possible to deliver the required volume of fuel to waters North of Lantau. This meant that search was restricted to sites south of the Ma Wan Channel and ruled out from further consideration a number of potentially viable alternative sites in waters north of Lantau, namely, Sham Shui Kok and Tuen Mun.
2.1.1.14 In 1994, two attractive sites in waters north of
Lantau (Tuen Mun Area and Sham Shui Kok) were revisited on the basis of the
possible implementation of the Tong Gu Channel.
It then transpired that the decision to implement Tong Gu Channel was
uncertain. Accordingly, these options
were again shelved.
2.1.1.15 Thus by 1994, a suitable permanent site had not been identified, requiring a temporary solution in order to secure an aviation fuel supply for the airport opening. The temporary solution comprised an AFRF just off Sha Chau and twin submarine pipelines connecting to the airport. Following the completion of an EPD and ACE approved EIA on the AFRF and its twin submarine pipelines, the temporary facility was gazetted in April 1995. However, the conditions of the Gazettal required, among other things, that a permanent facility be expedited. The Gazettal also stipulated that once the PAFF became operational, the facility at Sha Chau would only be used as an emergency back-up. Accordingly, the AFRF was developed, became operational in 1998 and currently operates as follows:
¨
Aviation fuel is transported from overseas
refineries by long voyages in ocean-going vessels (about 20,000 to 70,000 dwt),
which are normally not dedicated to shipment of aviation fuel. During the voyage there is a tendency for
small quantities of seawater to seep into the aviation fuel compartments in
these vessels.
¨
Upon arrival in
¨
Settlement and quality control checks are
currently carried out at Tsing Yi.
(However, this function will be replaced by the PAFF which will receive
aviation fuel tankers direct from overseas and provide for aviation fuel to
settle in tanks prior to carrying out quality control checks.).
2.1.1.16 The AFRF has been, and continues to be, operated
and managed in a professional and responsible manner and to date has performed extremely well, in
full compliance with all environmental commitments. These include:
¨
a zero-discharge policy for solid and liquid
wastes;
¨
robust and extensive EPD/AFCD approved spill
contingency planning;
¨
spill control and containment equipment is stored
on the AFRF ready for use, including 2 dedicated work boats on constant
standby;
¨
AFRF staff are routinely trained in spill
response in
conjunction with the statutory spill response authorities; and
¨
fuel delivery vessel crews have been trained in appropriate vessel
manoeuvring to minimise vessel impacts on dolphins.
2.1.1.17 As a result of the AFRF development, the designation of the Lung Kwu Chau and
2.1.1.18
The search for the PAFF
site in waters south of Lantau continued in parallel with the development of
the temporary facility at Sha Chau.
Thus, further studies were necessary and in 1998, following consultation
with Government, three options were identified south of the Ma Wan Channel,
namely East of Soko
2.1.1.19 Tsing Yi was considered in the study of sites south of Lantau to be less favourable than East of Sokos and Kau Yi Chau for the following reasons:
¨
Restrictions will preclude the construction of a
dedicated jetty. Reliance is thus placed
upon the willingness of the owners of the existing jetties (five in total) to
provide part-time use of their facilities for the airport needs.
¨
There are tank capacity constraints. The total available capacity cannot match the
ultimate needs of the airport.
¨
The components of PAFF at this site (e.g. jetties
and tanks) are widely spread over a distance of around 4km. Gathering lines to collect the fuel from each
individual tank farm and deliver it to a transfer point for pumping via twin
pipelines to the airport, are thus required.
The entire system of jetties, tanks, gathering lines and twin pipelines
with the associated controls, management and maintenance would be inherently
less efficient than a dedicated compact arrangement.
¨
The routes for the twin pipelines to the airport
have a number of problems which may reduce their durability and thus their
ability to provide a secure supply.
These problems include the possibility of accelerated corrosion induced
by stray currents (such as those produced by passage of trains or presence of
high voltage cables) and difficulties of construction through geological fault
zones.
¨
Tsing Yi therefore has uncertain timing, is less
efficient and less reliable and does not meet tank and jetty requirements. It was thus ruled out.
2.1.1.20 Meanwhile, the need to identify and develop a permanent site became urgent because it was known that, based on forecast growth, the AFRF at Sha Chau together with West Quay on the airport would reach their capacities by around 2007/2009.
2.1.1.21 In 1998, no site for PAFF had been found,
although the AFRF at Sha Chau was by then operational. This dilemma, in which a permanent, realistic option for a PAFF location had yet
to be identified, continued until 2000, along with increasing urgency.
2.1.1.22 At this time, a number of significant improvements related to safe passage of vessels through the Ma Wan Channel were being implemented, warranting further study of the then existing constraints to vessel traffic. A study was commissioned by the Airport Authority in 2000 to investigate the changes. This study determined that the use of the Ma Wan Channel for the transport of aviation fuel in ocean going tankers was acceptable, thus by 2001 the way was clear for re-consideration of PAFF sites at Sham Shui Kok, Tuen Mun West and Tuen Mun Area 38. The re-instatement of these three sites was reported to ACE on 18 December 2000 (copy of paper 38/2000 and minutes are attached at Appendix A(ii)). Subsequently, the Authority demonstrated to ACE that Tuen Mun Area 38 was the best available environmental option (copy of paper 50/01 and minutes of 17th December 2001 are attached at Appendix A(iii)).
2.1.1.23
The site search has covered a large number of sites in
western waters of
¨ Sha Chau (AFRF expansion);
¨ Airport;
¨ Ma Wan;
¨ Penny’s Bay;
¨ Mo To Chau (The Brothers); and
¨ Lung Kwu Chau.
2.1.1.24 In addition, sites at Bluff Point, Sham Wat, Tsing Yi, East of Sokos and Kau Yi Chau have also been ruled out for good reasons. Nevertheless, because these sites still remain theoretically possible, although not preferred, they are taken forward for analysis on a comparative basis, in the next section.
2.1.2 Comparison
of Alternative Sites
2.1.2.1 The process, briefly summarised above, of searching for a suitable PAFF site has involved undertaking a number of both preliminary and detailed feasibility studies and investigations. The criteria described in Section 2.1.1.6 have been used as a basis for assessing the feasibility of the various sites considered over this 10-year period. At the time of these feasibility studies, all criteria (including environmental criteria) were considered and discussed with Government, in determining the practicability of each site.
2.1.2.2 Section 2.1.3 below provides, for completeness, a comparison of the eight sites shown in Figure 2.1 and listed below, although a number of these sites have been ruled out as described above.
¨
Site 1 - Bluff Point (BP);
¨
Site 2 - East of Sokos (EOS);
¨
Site 3 - Kau Yi Chau (KYC);
¨
Site 4 - Sham Shui Kok (SSK);
¨
Site 5 - Sham Wat (SW);
¨
Site 6 - Tsing Yi (TY);
¨
Site 7 - Tuen Mun West (TMW); and
¨
Site 8 - Tuen Mun Area 38 (TMA 38).
2.1.2.3 Because the feasibility of PAFF sites was not assessed solely on environmental grounds in the historical feasibility studies, a summary considering all criteria is provided below.
2.1.3 Comparative
Environmental Assessment
2.1.3.1 The assessment of each site under each criterion is addressed below.
Water Depth
2.1.3.2 A water depth of 17 metres is required for vessel access. This natural water depth is available only at Tuen Mun Area 38 and Tsing Yi but also lies relatively close to Kau Yi Chau, East of Sokos and Tuen Mun West. However, there is no space available for a jetty to be located at Tsing Yi. Where such depth is not available, capital and maintenance dredging is required (which has potential environmental implications).
Environmental
Acceptability
2.1.3.3 A qualitative comparative environmental assessment is given in Appendix A(iv) and the results are given in Tables 2.1a and 2.1b below, for the construction and operational phases, respectively and summarized in Table 2.1c. This assessment of the site alternatives included the consideration of any risk to human life as detailed in the tables.
Table
2.1c Summary of Environmental
Comparison Results: Construction and Operational Phases
|
Phase |
Site 1 - BP |
Site 2 – EOS |
Site 3 - KYC |
Site 4 - SSK |
Site 5 - SW |
Site 6 – TY |
Site 7 - TMA 38 |
Site 8 - TMW |
|
Ranking
for Construction Phase |
4 |
8 |
3 |
5 |
6 |
2 |
1 |
7 |
|
Ranking
for Operational Phase |
6 |
4 |
3 |
5 |
8 |
2 |
1 |
7 |
Table 2.1a Construction
Phase Environmental Comparison
Criteria
|
|
Weighting
|
Site 1 Bluff Point |
Site 2 East of |
Site 3 Kau Yi Chau |
Site 4 Sham Shui Kok |
Site 5 Sham Wat |
Site 6 Tsing Yi |
Site 7 Tuen Mun Area 38 |
Site 8 Tuen Mun West |
Air Quality
Construction Air Quality Impacts |
Max Score Score out of 10 |
10 10.00 |
Low (0.75) 7.50 |
Low
(0.75) 7.50 |
Low
(0.75) 7.50 |
Medium
(0.5) 5.00 |
Low (0.75) 7.50 |
Very
low (1.0) 10.00 |
Very
low (1.0) 10.00 |
Medium (0.5) 5.00 |
Noise
Above Ground Nose Impacts Underwater Noise Impacts |
Max Score Score out of 15 |
15 3.00 12.00 |
Low
(0.75) Low (0.75) 11.25 |
Very
low (1.0) High (0.25) 6.00 |
Very
low (1.0) Low (0.75) 12.00 |
Medium
(0.5) Low
(0.75) 10.50 |
Low
(0.75) Low (0.75) 11.25 |
Very
low (1.0) Very
low (1.0) 15.00 |
Very
low (1.0) High (0.25) 6.00 |
Medium (0.5) High (0.25) 4.50 |
Water Quality
Water Quality Impacts |
Max Score Score out of 20 |
20 20.00 |
Low
(0.75) 15.00 |
Medium
(0.5) 10.00 |
Low
(0.75) 15.00 |
Low
(0.75) 15.00 |
Medium
(0.5) 10.00 |
Very
low (1.0) 20.00 |
Very
low (1.0) 20.00 |
15.00 |
Ecology
Marine Faunal Impacts Designated Ecological
Receivers |
Max Score Score out of 30 |
30 19.50 10.50 |
High
(0.25) Medium
(0.5) 10.13 |
Very
high (0) High
(0.25) 2.63 |
Medium
(0.5) Low
(0.75) 17.63 |
High
(0.25) Low
(0.75) 12.75 |
Very
high (0) Medium
(0.5) 5.25 |
Low
(0.75) Very
low (1.0) 25.13 |
Low
(0.75) Very
low (1.0) 25.13 |
High (0.25) Low (0.75) 12.75 |
Landscape and Visual
Landscape Resource Visual Impacts |
Max Score Score out of 15 |
15 6.00 9.00 |
Medium
(0.5) High
(0.25) 5.25 |
Medium
(0.5) Medium
(0.5) 7.50 |
Medium
(0.5) Medium
(0.5) 7.50 |
Medium
(0.5) High
(0.25) 5.25 |
Medium
(0.5) High
(0.25) 5.25 |
Low
(0.75) Low
(0.75) 11.25 |
Low
(0.75) Low
(0.75) 11.25 |
Medium (0.5) Medium (0.5) 7.50 |
Cultural Heritage
Terrestrial Cultural
heritage Marine Archaeology |
Max Score Score out of 10 |
10 2.00 8.00 |
Very
low (1.0) High
(0.25) 4.00 |
Very
low (1.0) High
(0.25) 4.00 |
Very
low (1.0) Medium
(0.5) 6.00 |
Very
low (1.0) High
(0.25) 4.00 |
Very
low (1.0) High (0.25) 4.00 |
Very
low (1.0) Very
low (1.0) 10.00 |
Very
low (1.0) Low
(0.75) 8.00 |
Very
low (1.0) 4.00 |
Risk
Construction Stage Risk |
Max Score Score out of 35 |
35 35.00 |
Very
low (1.0) 35.00 |
Very
low (1.0) 35.00 |
Very
low (1.0) 35.00 |
Very
low (1.0) 35.00 |
Very
low (1.0) 35.00 |
High
(0.25) 8.75 |
Very
low (1.0) 35.00 |
Very
low (1.0) 35.00 |
|
Maximum Score Score (out of 135) |
|
135 |
88.13 |
72.63 |
100.63 |
87.50 |
78.25 |
100.13 |
115.38 |
83.75 |
RANKING
|
|
|
4 |
8 |
2 |
5 |
7 |
3 |
1 |
6 |
Table 2.1b Operational Phase
Environmental Comparison
Criteria
|
|
Weighting
|
Site 1 Bluff Point |
Site 2 East of |
Site 3 Kau Yi Chau |
Site 4 Sham Shui Kok |
Site 5 Sham Wat |
Site 6 Tsing Yi |
Site 7 Tuen Mun Area 38 |
Site 8 Tuen Mun West |
Air Quality
Operational Air Quality
Impacts |
Max Score Score out of 5 |
5 5.00 |
Very
low (1.0) 5.00 |
Very low (1.0) 5.00 |
Very
low (1.0) 5.00 |
Low
(0.75) 4.00 |
Very
low (1.0) 5.00 |
Very
low (1.0) 5.00 |
Very
low (1.0) 5.00 |
Very
low (1.0) 5.00 |
Noise
Above Ground Nose Impacts Underwater Noise Impacts |
Max Score Score out of 10 |
10 2.00 8.00 |
Very
low (1.0) Low
(0.75) 8.00 |
Very
low (1.0) Very
low (1.0) 10.00 |
Very
low (1.0) Low
(0.75) 8.00 |
Low
(0.75) Low
(0.75) 7.50 |
Very
low (1.0) Medium
(0.5) 6.00 |
Very
low (1.0) Very
low (1.0) 10.00 |
Very
low (1.0) Very
low (1.0) 10.00 |
Very
low (1.0) Very
low (1.0) 10.00 |
Water Quality
Water Quality Impacts |
Max Score Score out of 15 |
15 15.00 |
Low
(0.75) 11.25 |
Low (0.75) 11.25 |
Low
(0.75) 11.25 |
Low
(0.75) 11.25 |
Medium
(0.5) 7.50 |
Very
low (1.0) 15.00 |
Very
low (1.0) 15.00 |
11.25 |
Ecology
Marine Faunal Impacts |
Max Score Score out of 20 |
20 20.50 |
Low
(0.75) 15.00 |
Very
high (1.0) 20.00 |
Low
(0.75) 15.00 |
Low
(0.75) 15.00 |
Medium
(0.5) 10.00 |
Very
low (1.0) 20.00 |
Very
low (1.0) 20.00 |
Low (0.75) 15.00 |
Risk
Hazard of Life Environmental Risk |
Max Score Score out of 35 |
35 19.25 15.75 |
Very
low (1.0) Medium
(0.5) 27.13 |
Very
low (1.0) High
(0.25) 23.19 |
Very
low (1.0) Low
(0.75) 31.06 |
Low
(0.75) Low
(0.75) 26.25 |
Very
low (1.0) Medium
(0.5) 27.13 |
High
(0.25) Low
(0.75) 16.63 |
Low
(0.75) Low
(0.75) 26.25 |
Low
(0.75) Low
(0.75) 26.25 |
Landscape and Visual
Landscape Resource Visual Impacts |
Max Score Score out of 15 |
15 6.00 9.00 |
High (0.25) High (0.25) 3.75 |
Medium (0.5) Medium (0.5) 7.50 |
Low (0.75) Low (0.75) 11.25 |
Low (0.75) High (0.25) 6.75 |
High (0.25) High (0.25) 3.75 |
Low (0.75) Low (0.75) 11.25 |
Very low (1.0) Low (0.75) 12.75 |
Low (0.75) Low (0.75) 11.25 |
|
Maximum Score Score(out of
100) |
|
100 |
70.13 |
76.94 |
81.56 |
70.75 |
59.38 |
77.88 |
89.00 |
78.75 |
RANKING
|
|
|
7 |
5 |
2 |
6 |
8 |
4 |
1 |
3 |
2.1.3.4 Throughout the site search, as provided in Appendices A(i), A(ii) and A(iii), AAHK has consulted the ACE to seek guidance.
Land Availability
2.1.3.5 Land is currently only available at Tuen Mun Area 38 and therefore, new reclamation will be required for the other sites. Tsing Yi is a special case (see Section 2.1.1.18). Reclamation has the potential to result in environmental implications, particularly in respect of water quality and marine ecology impacts, with associated potential environmental impacts and is undesirable, particularly when it has to be undertaken close to key environmentally sensitive areas. Given the likelihood that reclamation would be the least environmentally acceptable at Sham Wat, Bluff Point and East of Sokos, these sites would be least favoured.
Pipelines
2.1.3.6 Pipelines from Tsing Yi, Kau Yi Chau and East of Sokos are not viable because for Kau Yi Chau and East of Sokos, the pipeline would need to be in a bored tunnel, and for Tsing Yi, see Section 2.1.1.18. An alternative from East of Sokos is the installation of twin subsea pipelines going around the west of Lantau to the airport. This is undesirable because of its long length and greater potential impact on environmentally sensitive areas (including destruction of pristine seabed and potential impacts on the unspoilt coastline).
2.1.3.7 A bored tunnel must be of sufficient size for maintenance of both pipelines and it is undesirable for the following reasons (which are amplified in Section 2.2.1):
¨
There is a risk of delayed completion. Historically long, subsea bored tunnels are
prone to serious delay and even in the event of a smooth construction
programme, a bored tunnel could not be constructed within the required
timeframe.
¨
There would be a gradual build up of vapours in
the confined space of the tunnel. This
poses risks to maintenance crews. To
avoid such build up, ventilation shafts (with their own environmental impact)
could be constructed. Alternatively,
elaborate and time consuming purging procedures could be implemented when
tunnel entry is required. Neither option
is desirable.
¨
Spoil from tunnels is usually contaminated and
requires special treatment before disposal.
Timely Completion
2.1.3.8 A completion date as soon as possible is essential because the throughput capacity at Sha Chau and interim facility at West Quay is expected to be exceeded during 2007.
2.1.3.9 In addition, AAHK has made a commitment to ExCo that it will expedite the permanent pipeline and the following complications occur at the following sites:
¨
at Sham Shui Kok, the reclamation for the tank
farm lies over an existing sewage outfall.
Relocation of this outfall would be required before reclamation could
commence;
¨
at Tsing Yi, the presence of several third
parties (Oil Companies), with whom extensive negotiations would need to be
conducted before agreement to undertake the works could be put in place, means
that the timing to start of operations is highly uncertain; and
¨
at Tuen Mun West, an existing sewer outfall would
need to be diverted or avoided by the twin subsea pipelines.
Cost
2.1.3.10 AAHK operates within prudent commercial principles. Thus, where a cheaper alternative is available, then that site is preferred, subject to no insurmountable environmental impacts.
2.1.4.1 Comparison of sites based on all criteria is given in Table 2.2. Of the alternative sites considered, it is clear, from the assessment of all criteria that on all counts the site at Tuen Mun Area 38 is preferred. Furthermore it is demonstrated in this EIA that the Tuen Mun Area 38 site is environmentally acceptable for the PAFF.
2.1.4.2 Further details of the site layout at Tuen Mun Area 38 are provided in Section 3 of this EIA.
Site
|
CRITERIA |
||||||||
|
Acceptable Water Depth? |
Sufficient Land Available? |
Viable |
Timely Completion Possible? |
Relative Construction Cost? |
Environmental Ranking(+)
|
Acceptable to ACE (and/or) Green Groups |
Acceptable Overall? |
||
|
Construction |
Operation |
||||||||
|
1. Bluff Point |
No |
Currently no land –
therefore would need reclamation8 |
Yes |
No |
1.4C |
4 |
6 |
No (near sensitive
coastline and in an area of pristine seabed) |
No |
|
2. East of Sokos |
No (but deepwater is
relatively close) |
Currently no land –
therefore would need reclamation8 |
No (Bored Tunnel or
alternatively long twin subsea pipelines) |
No |
3.1C |
8 |
4 |
No (environmentally
sensitive area, cost too high and timing too long/uncertain) |
No |
|
3. Kau Yi Chau |
No (but deepwater is
relatively close) |
Currently no land –
therefore would need reclamation8 |
No (Bored Tunnel only) |
No |
2.9C |
3 |
3 |
No (environmentally
sensitive area, cost too high and timing too long/uncertain) |
No |
|
4. Sham Shui Kok |
No |
Currently no land –
therefore would need reclamation8 |
Yes (although difficulties
would be encountered) |
No |
1.5C |
5 |
5 |
No (environmentally
inferior to Tuen Mun Area 38) |
No |
|
5. Sham Wat |
No |
Currently no land –
therefore would need reclamation8 |
Yes |
No |
1.8C |
6 |
8 |
No (near sensitive
coastline and in an area of pristine seabed) |
No |
|
6. Tsing Yi |
Yes |
Already reclaimed |
No (difficulties would be
encountered) |
No |
2.7C |
2 |
2 |
(inferior to EOS & KYC) |
No |
|
7. Tuen Mun Area 38 |
Yes |
Already reclaimed |
Yes (short length across |
Yes |
C |
1 |
1 |
Yes |
Yes |
|
8. Tuen Mun West |
No (but deepwater is
relatively close) |
Currently no land –
therefore would need reclamation8 |
Yes (but a long length lies
in |
No |
1.9C |
7 |
7 |
No (environmentally
inferior to Tuen Mun Area 38) |
No |
*Green Groups +Lower
number indicates a better ranking 8 Potential impacts resulting
from the reclamation have been included under Environmental Ranking
Preliminary Construction Cost
of PAFF at Tuen Mun Area 38 is represented by C
2.2.1.1 Two principal route alignments have been assessed for the pipeline linking the PAFF at Tuen Mun Area 38 site to the airport. The primary option is to capitalise on the existing pipeline that currently runs from the temporary jetty and reception facility at the Airport Fuel Receiving Facility (AFRF) at Sha Chau and thus tie in with this pipeline. An alternative option is to construct a completely new pipeline from the proposed PAFF site direct to the west side of the HKIA. The two routing options are illustrated on Figure 2.2.
2.2.1.2 Other options comprising a connection of the pipeline from Tuen Mun Area 38 to either the north or east of the airport have also been considered. However, as shown in Figure 2.3, the northern pipeline corridor is not viable due to the presence of the Contaminated Mud Pits at East of Sha Chau which dominate the seabed area, north of the airport apron. It is not possible to pass through these pits and as the pits are some 30m deep, it is not viable to pass underneath. In respect of the eastern pipeline corridor, pipelines within this corridor, as shown in Figure 2.3 have also been dismissed for various reasons as summarised below:
¨
the length of pipeline across
¨
the pipeline will need to either go under or
around the sewage outfall from the River Trade Terminal at Pillar Point. The latter brings it close to the
Contaminated Mud Pits at East of Sha Chau to the south;
¨
the pipeline would need to pass under the HV
cable with a risk of corrosion induced by stray currents. A further cable is planned by CLP with
similar risks;
¨
there are plans to construct a Lantau / Tuen Mun
submerged tunnel in the future and the fuel pipeline would need to allow for
this by going deeper;
¨
the pipeline enters the marine traffic restricted
area and more importantly the marine exclusion zone of the southern runway
which would result in the runway having to be shut down during the pipeline
construction;
¨
the pipeline passes close to the potential
contaminated mud pit to the east of the airport and, thus, the pipeline
construction activities may be in close proximity to contaminated mud dumping
operations;
¨
the route on the airport, unless it is in a bored tunnel, passes under
or close to already developed areas such as
¨
in passing under the MTRC railway, the pipeline
may be subject to stray current and hence induced corrosion.
2.2.1.3 Overall, the constraints on options to the east reduce the pipeline viability and, in addition, the route will be considerably longer than that to Sha Chau but approximately the same as to the airport directly.
2.2.1.4 Thus, the western route corridor constitutes the only practical option, with the two alternatives being a pipeline directly to the airport or one which connects to the existing AFRF at Sha Chau. In order to select the best pipeline option of the two viable alternatives on environmental grounds, a comparative assessment of the relative merits and disadvantages has been undertaken. Details of the comparison are presented below.
2.2.1.5 For the purposes of this assessment it has been assumed that dredging would be needed during the construction of the pipelines. Other possible techniques include the use of a bored tunnel, directional drilling and ploughing but each of these have engineering, programme, environmental and/or cost constraints as detailed in the sections below.
2.2.1.6
Drill and
blast tunneling techniques are commonly adopted in the hard rock of
2.2.1.7 The most straight forward and least risk solution to excavate an opening for the sections of underwater pipeline would be to use one or two tunnel boring machines (TBM). TBMs are probably also the most cost-effective way to excavate the tunnel. The smallest practical TBM diameter for the lengths of tunnel envisaged is between 2.5m and 3.5m. The appropriate type of TBM for this type of tunnel is an electric-hydraulic driven machine. Broken rock would be carried away via a screw conveyor from the face of the machine feeding either a long belt conveyor or small gauge railway cars. Small gauge railway cars would be considered most suitable for this project and about 15 to 20 tonnes of broken rock will need to be removed every hour at typical rates of progress.
2.2.1.8 A total of about 210,000m3 of material would be required to be removed for the diameter tunnels required, including material for the shafts and the reclamation needed at Sha Chau (see Section 2.2.1.9), which is only slightly smaller that the marine mud generated by the dredging for pipeline Option 1 (see Table 2.3) but half the amount for Option 2. However, about 25% of this material is expected to be contaminated with hydraulic oil and must be treated before disposal. This represents a significant environmental drawback. Mucking out of the tunnels and disposal of the spoil would need to be addressed. Whilst there is adequate space at Tuen Mun Area 38 to accommodate a small stockpile, this will have limited capacity, demanding regular clearing to a suitable disposal site.
2.2.1.9
Also of key concern would be the logistics and
selection of the size of tunnel access shafts. These will be sunk through
reclamation to meet firmer strata at greater depth. Support of the shafts will
require substantial diaphragm walling or a steel cofferdam. Sizing and associated cost implications must
be balanced against provision of adequate space for access, mucking out and
ventilation requirements. The shafts will also require adequate working space
around them which will demand additional reclamation work or land to be made
available and where these occur in the sea and this will have associated
impacts associated with permanent loss of seabed. For the Option 1 pipeline, the shaft at Sha
Chau would require the reclamation of a piece of land with a useable area of
50m by 50m and this would need to be built in the
2.2.1.10 In respect of the Option 2 pipeline, a reclamation of the same size would also be required in the area just off the airport apron. However, despite the area of affected seabed as noted above, a reclamation to the west of the HKIA would have constraints during the construction period associated with blocking the access for sea rescue, conflicts with the marine exclusion and height restriction zones and potential glare issues affecting the flight path. Based upon these potentially serious operational factors, the option 2 bored tunnel is not considered practicable.
2.2.1.11 Pre-drilling along the tunnel axis will be required in order to identify sections of poor ground. Of particular importance will be the quantity of water inflow expected. Highly fractured rock and open joints are often associated with faults and shears. These promote the ingress of large quantities of water. This exacerbates ground support problems associated with fractured rock and/or fault gouge capable of producing a ground support problem that cannot be practically overcome behind the advancing TBM. Such inflows can be large and halt the works for a considerable period of time. A metre length of 0.4mm wide fissure in rock subjected to 100m of head can produce 500 litres per minute. Grouting of the ground ahead of the advancing tunnel is the most appropriate solution for a bored tunnel, with pre-grouting being more preferable to post-grouting. Only spot or targeted grouting is envisaged as being necessary where pre-drilling has identified particular areas of potential inflow. More comprehensive measures would possibly be required in the areas of the faults, where closely spaced grout holes may be required to displace and wash out gouge in order to allow the grout to penetrate and create an adequate seal. A number of stages may be required in difficult ground. Pre-grout holes are typically 20-25m long and at 2-3m centres for all-round coverage.
2.2.1.12 For the above reasons, the expected rate of progress of shaft sinking and tunnel boring is slow and would add at least an additional year to the overall PAFF programme. Based upon a required operational date of 2009 for the PAFF, it is clear that a tunnel could not be completed in time to meet the forecast date when the facility at Sha Chau reaches its limit of capacity.
2.2.1.13 During operation, maintenance of the pipeline would be required periodically. For this purpose, the air in the tunnel must be fresh for the safety of personnel. This can be achieved either by provision of vent shafts or purging the air with special equipment. In the case of ventilation shafts, this increases the construction phase impacts associated with the use of this technique and in both cases would require long term (for the life of the pipeline), power requirements to provide the fresh air. It should be noted that maintenance in such confined spaces also provides safety issues for personnel.
2.2.1.14 A further factor for consideration during the operational phase, is the control of fuel spill. Tunnelled sections of the line cannot be economically kept drained unless costly lining systems are adopted. It will, therefore, be necessary to allow the tunnelled sections of the alignment to flood once the pipeline installation is complete. In the event of a failure of the line in a flooded tunnel it will be necessary to pump out the tunnel rapidly to effect timely repairs. There will be a significant volume of oil contaminated sea water to be handled in these circumstances. While the impacts can be minimised by suitable surveillance and the provision of a segmentation system in the lines which would minimise the quantity of oil lost in the event of an incident, the requirement to handle, treat and dispose of large quantities of waste water is an environmental disadvantage associated with the use of a tunnel.
2.2.1.15 In summary the main disadvantages of a bored tunnel are as follows:
¨
significant environmental issues associated with treatment and disposal
of contaminated spoil, temporary loss of seabed for the shafts potentially
within the
¨
operational constraints associated with shaft reclamation west of
airport;
¨
the pipeline could not be completed within the required timeframe; and
¨
maintenance of the pipeline is difficult and carries safety risks.
Directional Drilling
2.2.1.16 The
use of horizontal directional drilling (HDD) for short bores is considered
practical only for short lengths of tunnel. Current technology has allowed
holes of up to 1500mm diameter to be drilled for lengths of up to 1500 to
1750m. However, the crossing being considered is considerably longer than this
and is assumed to be carried out within the rock strata. Bore size is limited
by the reamer arrangement although it is possible to pass multiple reaming
tools through the pilot hole in order to increment the final bore diameter. At
present a bore limitation of about 800 to 1000 mm represents a practical
limitation on the technique. Based on
the limitation of the distance, it is likely that the technique may only be
applicable to the
2.2.1.17 However, it should be noted that bentonite will be required where directional drilling techniques are to be adopted and spillage of bentonite where breakthrough of the bores occurs in inevitable. Thus, there is potential for the spoil to be contaminated which will not occur with conventional dredging. Thus, the material to be excavated will require treatment or disposal to contaminated mud pits and will not be suitable for reuse as public fill which respresents an environmental disadvantage.
2.2.1.18 In addition to the above, there are many implementation difficulties associated with this technique which reduce its viability as follows:
¨
Collapse of the pilot hole or reamed out hole prior to casing
installation is a possibility but can be overcome by removing the drill string,
grouting up the end of the hole and then drilling through the grouted up
section of ground. Jamming of the drill string due to collapsing ground is
however a real risk.
¨
There will be a tendency for the HDD pilot hole to follow pre-existing
fractures within the rock-mass. In addition, drills tend to align themselves
perpendicular to the fabric or bedding of the rock through which they are
drilling. In the area to be drilled for the PAFF project, some wandering of the
pilot hole due to fractures and fabrics can be expected. This would require
careful monitoring whilst drilling in order to avoid significant deviations.
¨
The HDD would need to penetrate a variety of geotechnical conditions,
such as public fill, rock mound, alluvium, completely decomposed granite before
encountering the bed rock described above.
It is difficult to overcome this variability, which experience has shown
could result in the drill to become stuck causing delays and potentially a new
hole would be required to be started.
This has both serious economic and programme implications.
¨
It is necessary to adjust the buoyancy of the final pipeline in order
to reduce its effective weight to almost zero while it is being pulled through
the flooded reamed directionally drilled hole. This places limitations on the
pipe wall thickness to diameter relationship.
¨
Once installed in the directionally drilled and reamed bore there is no
ability for subsequent access. Repairs to the line would necessitate total
replacement of the directionally drilled section.
2.2.1.19 In
summary, the technique is appropriate for short lengths of tunnel only and would
in practice be suitable for the
Ploughing
2.2.1.20 ‘Post trenching’ techniques such as ploughing can be used to form a furrow on the seabed into which the pre-laid pipeline falls into. This method dispenses with the need to dredge a trench and there is no requirement to bring spoil to the surface for disposal elsewhere. Soil displaced during ploughing is simply pushed to the side of the pipeline and left to erode. However, with this method it would not be possible to place the required rock armour cover to lie flush with the existing sea floor. Any armour cover would need to be placed as a mound sitting proud of the seabed which would increase the risk of subsequent mechanical damage in the operational phase, from dragged anchors, for example. This represents a major design failing and this option is therefore ruled out.
2.2.1.21 The same limitation would apply to other post trenching methods such as jetting or other such hydraulic means to fluidise the seabed beneath the pipeline. In addition, to the above constraints associated with these techniques, potentially substantial sediment plume that would be generated during fluidisation (ERM 1995).
2.2.1.22 Thus, it is proposed that the pipeline be constructed using dredging techniques, with neither the tunnel, directional drilling nor post trenching techniques providing the preferred method.
2.2.1.23 The
pipeline option to the existing AFRF (Option 1) would necessitate the dredging
of a trench of approximately 4.8km in length from the PAFF site at Tuen Mun Area
38 to tie in with the existing pipeline at Sha Chau and would optimise the use
of the existing pipeline. Approximately
400m of this new trench would have to be dredged within the
2.2.1.24 The
pipeline option connecting directly to the airport (Option 2) would involve
laying a completely new pipeline from the PAFF site to the HKIA platform. The pipeline would be approximately 11.2km in
length and would be routed to avoid the
2.2.2 Comparative
Assessment of Options during the Construction Phase
Key Issues
2.2.2.1 The two pipelines are of significantly different lengths and, with the exception of the first few kilometres which follow similar alignments, traverse different routes. This will affect their respective impacts on water quality and ecology during construction. Similarly, there could be marine archaeological implications in the event that the alignment would pass through an area of seabed artefacts of archaeological interest requiring rescue or other mitigation. The routing will also have a bearing on the operational risk associated with pipeline failure in the operational phase.
2.2.2.2
The shorter pipeline Option 1 would involve
construction works in the Lung Kwu Chau and
2.2.2.3 There are no significant differences in the likely impact to air quality, noise or visual aesthetics associated with the pipelines and therefore these issues are not addressed in the comparative assessment.
2.2.2.4 The assumed lengths and approximate in-situ
dredging volumes for the pipelines are presented in Table 2.3. It should be noted that works for the
pipeline dredging in the areas other than the
Table 2.3 Pipeline
Options 1 and 2 Pipeline Lengths and Dredge Volumes
Option
|
Route |
Length (km) |
(1) Dredge Volume (m3) |
|
1 |
Tuen
Mun Area 38 to AFRF at Sha Chau |
4.8 |
340,000 |
|
2 |
Tuen
Mun Area 38 to HKIA |
11.2 |
563,000 |
Note (1) : Based upon
indicative trench cross sections detailed in Section 3.
2.2.2.5 It can be seen that the Option 2 pipeline route is more than double the length of the Option 1 route and would involve dredging of more than twice the volume of sea bed sediment. For the purposes of this assessment it is assumed that very similar construction methods would be adopted for either route and thus, the instantaneous levels of suspended sediment observed during construction emanating form the work point are likely to be similar for any given activity. However, the period of construction for the longer Option 2 will be approximately twice as long. Thus Option 1 is significantly advantageous from this perspective.
2.2.2.6
Option 1 requires dredging in the
2.2.2.7 The water quality modelling results discussed in Section 6 of this report indicate that no identified sensitive receivers would be adversely affected by disturbances to water quality during the construction period for Option 1, including the Marine Park. There are no sensitive receivers unique to the Option 2 as opposed to Option 1 and therefore, both options are not expected to result in adverse water quality impacts.
2.2.2.8
Thus, both options are similar in that no significant
impacts are expected to any sensitive receiver from sediment plumes caused by
the construction works. However, Option
1, notwithstanding the fact that it enters the
Waste Management
2.2.2.9 Seabed sediments dredged to form the pipeline trench will require transport off-site and suitable disposal at a marine fill area. As indicated in Table 2.3, the total quantity of spoil arising for Option 2 amounts to an estimated 563,000 m3 compared to 340,000m3 for the shorter Option 1. An option which generates the least amount of waste is preferable and thus, Option 1 is recommended from a waste management perspective.
Ecology
2.2.2.10 As the pipeline options are in relative close proximity, only the ecological receivers that are known to differ in their distribution along the options have been assessed in the comparative assessment. A comparative ecological assessment of the two pipeline options is provided below.
Benthic Habitat
2.2.2.11 The benthic habitat characteristic of both pipeline corridor options comprises of a soft-bottom material composed of silts and clay as a homogenous layer or in loosely packed mud clasts bound in a puzzle fabric (Binnie Consultants, 1995; ERM, 1999). Based on grab samples taken at various locations in the Northwestern waters, the macro-invertebrate assemblages present are likely to be similar along both pipeline routes (Greiner-Maunsell, 1991; ERM, 1997; Mouchel, 2001a) and are characteristic of soft-bottom benthic communities throughout Hong Kong (Shin and Thompson, 1982).
2.2.2.12 The
benthos distributed along the two pipeline options are generally comprised of
filter-feeding and deposit-feeding representatives including polychaetes,
molluscs, crustaceans and echinoderms and these most common representatives
typically account for 95% of the benthic assemblage (ERM, 1997) and are
characteristic of soft-bottom benthic communities throughout
2.2.2.13 Temporary losses of benthos attributable to each pipeline option have been assessed in terms of dislodgement of macro-infauna (interpreted in terms of losses from the system/ study area and calculated using biomass) and hence possible reduction in food prey items to fish and higher trophic levels, including dolphins. The potential losses to each pipeline of macroinfaunal biomass are presented below in Table 2.4.
Table 2.4 Predicted Temporary
loss of Macro-infauna Biomass Attributed to Each Pipeline Option
|
Pipeline Option |
Seabed lost (m2) |
Estimated loss of biomass (kg)1 |
Option 1
|
124,975 |
3,642 |
|
Option
2 |
269,525 |
7,854 |
1Calculation is based on the macro-infauna
collected at various stations in the Northwestern waters in May 2001 which
showed an approximate (wet weight) biomass of 29.14g m-2 in
surficial sediment (Mouchel, 2001a).
2.2.2.14 Results
from the assessment of both submarine pipeline options on potential temporary
loss of food sources to marine biota, such as fisheries and dolphins, indicated
that the lowest source of biomass loss was, as expected, associated with the
shorter fuel pipeline that links directly to the AFRF. The loss of macro-infaunal prey items (calculated
as biomass) to higher trophic levels, however, is not considered to represent a
significant impact, given the homogenous distribution of these food items in
the Northwestern waters and the likelihood that dislodged prey items would not
necessarily be lost from the system.
However, Pipeline Option 1 was calculated to lose approximately 3,642 kg
of biomass over the entire length; whereas the longer pipeline Option 2 located
to the south of the
2.2.2.15 The temporary losses of macro-infauna calculated for both options are considered to be an overestimate of the losses as not all infauna would be lost from the system and with respect to the marine benthic communities, the impacts from either of the pipeline options are, therefore, judged to be similar and insignificant from a conservation perspective.
2.2.2.16 However,
it can be seen that the degree of disturbance to the benthic habitat and its
loss of function is in proportion to the length of the pipeline. While both options have to pass through the
dredged channel for the Castle Peak Power Station (CPPS), as shown in Figure
2.4, the alignment of Option 1 will also pass through the existing disturbed
area of the AFRF access channel for approximately half of its length, with 400m
within the
Corals
2.2.2.17 There
are few coral communities present of note in the vicinity of either pipeline
route with predominantly wide-spread (mostly soft-coral) species recorded. Soft
corals (sea pens such as Pteroides esperi)
are widespread throughout the seabed (e.g., Greiner-Maunsell, 1991; Mouchel,
2001a; 2001b) of both pipeline options (as well as elsewhere in
2.2.2.18 The water quality modelling (based on suspensions of sediment attributable to worst-case trailer suction hopper dredging; see Section 6) for pipeline laying in the study area predicted that the elevations in suspended solids would be highly localised and mostly confined to the bed layer and well within the range of natural variability for Northwestern waters. Suspended solids released through dredging activity do not, therefore, represent any concern to either the hard or soft corals present in the study area.
2.2.2.19 Although the potential for impacts to corals from suspended solids during construction phase activity is insignificant, as the dredging is longer for Option 2 which will lead to a greater loss of seabed (and hence soft-bottom seabed containing soft corals), the shorter Option 1 is preferred. There is, however, no clear preference for either pipeline option based on the few protected hard corals present in the study area. The potential for greater disturbance impacts (loss of seabed) are, therefore, higher for the longer Option 2.
Horseshoe Crab
2.2.2.20 There
are three species of horseshoe crab reported to regularly occur in
Indo-Pacific Humpback Dolphin
2.2.2.21 Neither route would be expected to result in any significant impact to the dolphin population when the PAFF is operational. Impacts on the dolphin may arise from temporary disturbance during the construction phase. In particular, cetaceans are known to be sound-sensitive and generally avoid areas subjected to high noise disturbance (Wursig et al., 2000). Anecdotal evidence suggests that the dolphins avoided the area around The Brothers during the airport construction (although this was a considerably larger project than the PAFF) however they returned on cessation of construction activities suggesting that disturbance impacts are transient and only present during the construction phase. Further evidence for noise-induced avoidance was observed immediately after the AFRF construction. Immediately following construc