Contents
Appendices
Appendix 12A
Environmental Impact Assessment Ordinance, Technical Memorandum – Annexes 10
and 19
Appendix 12B
Guidelines for Marine Archaeological Investigation (MAI)
Appendix 12D
Geophysical Surveys Plots
Figures
Figure 12.1
MAI Study Area and Geophysical Survey Area
Figure
12.3 Proposed
Reclamation Method and Arrangement for HKBCF
Figure
12.4 Cross-sections
of Seawall
Figure
12.5 MAI Drive
Survey Photographs
In accordance with the EIA Study Brief, a Marine Archaeological Investigation (MAI) was commissioned to cover the seabed which will be impacted by the construction of Hong Kong Boundary Crossing Facilities (HKBCF). The aim of the MAI is to assess the impact of the HKBCF on marine archaeological resources and recommend any mitigation measures, if necessary.
The MAI comprises five tasks:
· Task 1: Baseline Review to assess the archaeological potential of the study area from a desk based review of existing literature;
· Task 2: Geophysical Survey data analysis to obtain detailed information about the seabed and sub-surface sediments;
· Task 3: Establish archaeological potential and assess the location and significance of any seabed features requiring further investigation and evaluation;
· Task 4: Diver inspection of seabed features;
· Task 5: Assess the impact of the construction of the HKBCF on archaeological resources, if present, and recommend a mitigation strategy, if necessary.
The MAI covers the footprint of the HKBCF and associated installations plus a buffer zone of 100m to allow for the impact of working vessels during construction. The HKBCF layout and MAI study area are shown in the Figure 12.1.
12.1.4 Legislation and Standards
The legislation, standards, guidelines and criteria relevant to the consideration of underwater cultural heritage impacts under this study include the following:-
· Antiquities and Monuments Ordinance;
· Environmental Impact Assessment Ordinance;
· Technical Memorandum on Environmental Impact Assessment Process; and
· Guidelines for Marine Archaeological Investigation.
12.1.4.1 Antiquities and Monuments Ordinance
Legislation relating to antiquities is set out in the Antiquities and Monuments Ordinance (Chapter 53 of the Laws of Hong Kong), which came into force on 1 January 1976. The Antiquities and Monuments Ordinance provides statutory protection against the threat of development on Declared Monuments, historical buildings and archaeological sites to enable their preservation for posterity.
The
Ordinance contains the statutory procedures for the Declaration of Monuments.
The legislation applies equally to sites on land and underwater. The
purpose of the Ordinance is to prescribe controls for the discovery and
protection of antiquities in
· Human artefacts, relics and built structures may be gazetted and protected as monuments. The Antiquities Authority may, after consultation with the Antiquities Advisory Board (AAB) and with the Chief Executive’s approval, declare any place, building, site or structure which the Antiquities Authority considers to be of public interest by reason of its historical, archaeological or palaeontological significance.
· The discovery of an Antiquity, as
defined in the Ordinance must be reported to the Antiquities Authority (the
Authority), or a designated person. The Ordinance also provides that, the
ownership of every relic discovered in
· No archaeological excavation may be carried out by any person, other than the Authority and the designated person, without a licence issued by the Authority. A licence will only be issued if the Authority is satisfied that the applicant has sufficient scientific training or experience to enable him to carry out the excavation and search satisfactorily, is able to conduct, or arrange for, a proper scientific study of any antiquities discovered as a result of the excavation and search and has sufficient staff and financial or other resources to enable him to carry out the excavation and search satisfactorily.
· Once declared a site of public interest, no person may undertake acts which are prohibited under the Ordinance, such as to demolish or carry on building or other works, unless a permit is obtained from the Antiquities Authority.
The Ordinance defines an antiquity as a relic (a moveable object made before 1800) and a place, building, site or structure erected, formed or built by human agency before the year 1800. Archaeological sites are administratively classified into two categories, namely:-
·
· Recorded Archaeological Sites – those which have not been declared but recorded by the AMO under administrative protection.
It should also be noted that the discovery of an antiquity under any circumstances must be reported to the authority, i.e. the Secretary for Development or designated person. The authority may require that the antiquity or suspected antiquity is identified to the authority and that any person who has discovered an antiquity or suspected antiquity should take all reasonable measures to protect it.
12.1.4.2 The Environmental Impact Assessment Ordinance
Since the introduction of the 1998 Environmental Impact Assessment Ordinance (EIAO) (Cap. 499), the Antiquities and Monuments Office (AMO) have the power to request a MAI for developments affecting the seabed. Its purpose is to avoid, minimise and control the adverse impact on the environment of designated projects, through the application of the Environmental Impact Assessment (EIA) process and the Environmental Permit (EP) system. The EIAO stipulates that consideration must be given to issues associated with cultural heritage and archaeology as part of the EIA process. Annexes 10 and 19 of the EIA Technical Memorandum (EIAO-TM) outline the criteria for evaluating the impacts on sites of cultural heritage and guidelines for impact assessment, respectively.
The EIAO-TM identifies a general presumption in favour of the protection and conservation of all sites of cultural heritage and requires impacts upon sites of cultural heritage to be ‘kept to a minimum’. There is no quantitative standard for determining the relative importance of sites of cultural heritage, but in general sites of unique, archaeological, historical or architectural value should be considered as highly significant.
12.1.4.3 Technical Memorandum on Environmental Impact Assessment Process
The general criteria and guidelines for evaluating and assessing impacts to Sites of Cultural Heritage are listed in Annexes 10 and 19 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM). It is stated in Annex 10 that all adverse impacts to Sites of Cultural Heritage should be kept to an absolute minimum and that the general presumption of impact assessment should be in favour of the protection and conservation of all Sites of Cultural Heritage. Annex 19 provides the details of scope and methodology for undertaking Cultural Heritage Impact Assessment, including baseline study, impact assessment and mitigation measures. The full document is included in Appendix 12A.
12.1.4.4 Guidelines for Marine Archaeological Investigation
The AMO have issued Guidelines for Marine Archaeological Investigation (MAI) which detail the standard practice, procedures and methodology which must be undertaken in determining the marine archaeological potential, presence of archaeological artefacts and defining suitable mitigation measures. The full document is included in Appendix 12B.
This MAI follows the methodology set out in Annexes 10 and 19 of the EIAO-TM. (Appendix 12A) and the Guidelines for MAI issued by the AMO (Appendix 12B).
A Baseline Review was undertaken to compile a comprehensive inventory of cultural heritage resources of the Study Area. The Review established the historical profile and potential for cultural heritage sites and included:-
· Marine charts records held in
British Library and National Maritime Museum Library in
· Publications on local historical, anthropological, archaeological and other cultural studies; and
· Unpublished papers, records, archival and historical documents held in local libraries and other government departments.
All
archives holding information on shipwrecks in
The survey was carried out by EGS under the Geophysical Survey Term Contract Works issued by Civil Engineering and Development Department. The surveys were carried out during November and December of 2008.
The marine geophysical survey was carried out as part of the ground investigation for the HKBCF project. The objectives of the survey were:-
· To map sea bed levels in detail;
· To map features on the sea bed such as shipwrecks, rock outcrops and debris;
· To map the geological succession in the study area; and
· To locate the position of the existing utilities.
Although the survey was designed to meet the requirements of the engineering site investigation the data was sufficiently detailed to be adopted for the archaeological assessment.
12.2.3.2 Equipment
The following equipment was mobilised onboard the commercially licensed survey vessel.
Table 12-1 Equipment for Licensed Survey Vessel
|
Equipment |
Qty |
|
C-Nav GcGPS |
1 |
|
The EGS computerised navigation package v1.2 and PC |
1 |
|
Knudsen echo sounder |
1 |
|
The Reson 8125 multibeam system |
1 |
|
Swath PC |
1 |
|
Seismic profiler |
1 |
|
Hydrophone |
1 |
|
EGS TVG console |
1 |
|
|
1 |
|
DF1000 side scan sonar system with digital tow fish |
1 |
|
TSS Gyro compass |
1 |
|
Valeport velocity profiler |
1 |
|
TSS DMS 3-05 heave motion compensator |
1 |
|
Seaspy magnetometer |
1 |
A speedboat/sampan was mobilized to carry out echo sounding survey over the very shallow water area. The following equipment was used for the small boat survey.
Table 12-2 Equipment for Small Boat Survey
|
Equipment |
Qty |
|
C-Nav GcGPS |
1 |
|
The EGS computerised navigation package v1.12 and PC |
1 |
|
Knudsen echo sounder |
1 |
|
TSS HS50 heave motion compensator (SBES) |
1 |
|
KVH Azimuth 1000 |
1 |
The survey vessel was located with a globally corrected Global Positioning System (GcGPS) unit called C-Nav, for which no shore based differential correction transmitter is required. The system provides corrected positions to an accuracy of +/- 0.3m without the need for a shore-based transmitting system.
The EGS computerized navigation system was added to the positioning system to control the steering of the boat along the traverses specified, and to log all horizontal and vertical control data.
This system provides the user with a dynamic analogue and digital screen display on which the following are continuously updated:-
· Skewed grid set parallel to the desired line direction;
· Boat position;
· Water depth;
· Date and Time; and
· GcGPS diagnostics enabling quality control.
Calibration, Accuracy and Quality Assurance
The positioning system was calibrated by checking the co-ordinates displayed by the navigation system at the previously co-ordinated point located at the Tuen Mun typhoon shelter. Carrying out the above quality assurance checking procedure ensured an accuracy of +/‑1m or better.
Location of Tidal Measurements
Tidal levels were recorded at Tung Chung and tidal data collected were used to reduce all echo sounding data to Principal Datum, Hong Kong (PD).
This survey was carried out relative to Hong Kong Principal Datum. For reference, Chart Datum is 0.15m below Principal Datum (Reference: Hydrographic Office, Marine Department, Government of the HKSAR, 2005, Charts for Local Vessels).
Operating System on Board the Survey Vessels and in the Office
EGS has developed the C-View operating and interpretation software package. This system was installed on survey vessels and in the office. The system provided screen displays on up to three monitors for seismic profiling and side scan systems. Full operating systems coverage was provided, to enable the best survey records to be obtained. All raw data was logged digitally.
Side Scan Sonar Interpretation was carried out in the office; interpretation on the screen was then directed straight to Autocad without the need for further re-digitizing. Seismic data interpretation was carried out from the paper records.
The swath (multibeam echo sounding), seismic, side scan sonar and magnetic surveys were carried out from a Class IV survey vessel, M V Wing Hung 2.
Main traverses for the swath, seismic and side scan sonar surveys were set at 40m intervals with cross lines at 200m intervals. Infill lines for swath data were defined on site to ensure full coverage.
The line spacing for echo sounding measurements by echo sounder were set at 10m intervals with cross lines at 50m intervals.
12.2.4.3 Swath (Multibeam) Bathymetry
Seabed level observations were made with a multibeam echo sounder system with the transducers mounted over the starboard side of the survey vessel. The GcGPS antenna was mounted directly above the transducers and as such the swath transducer acted as the datum for the survey vessel.
The swath system is a multibeam echo sounder. Instead of transmitting a single vertical pulse, which provides a record of water column thickness beneath the vessel track, the swath measures the same type of data over a 'fan' on both sides of the vessel.
The Multibeam Echo Sounder (MBES) system requires careful calibrations. A potential source of error relates to the speed of sound in water; the MBES system requires the speed of sound be measured through the water column, and for these data to be entered into a file which is accessed by the MBES acquisition and processing software. On the west side of Hong Kong near the Pearl Estuary the speed of sound can vary significantly near the sea surface; therefore a speed velocity probe was installed at MBES transducer so that measurements are recorded at all times during the survey and the corresponding corrections can be made within the MBES system in real-time.
In addition, a patch test is required to calibrate system components, as follows:-
· Navigation Delay
A survey line is set exactly over a well-defined feature, such as a rock outcrop, a significant slope or a man-made structure. The line is run twice in the same direction, once at the slowest possible speed and once at the highest speed.
· Pitch Offset
A survey line is set exactly over a well-defined feature. The line is run in opposite directions at the same speed.
· Roll Offset
A survey line is set over an area with a flat and featureless seabed. The line is run in opposite direction at the same speed.
· Yaw (Heading) Offset
Two parallel lines are set to either side of a well-defined feature with the feature positioned in the middle of the two lines. The off-track distance between the feature and the lines are selected according to water depth and the fan width of the MBES system, so that the feature will be detected at the outer part of sounding “fan”. The lines are run in the same direction at the same speed; once passing the feature to Port and once to Starboard.
By applying appropriate algorithms to match the apparent differences in the positions of the selected feature and the seabed topography measured in the individual calibration line, these calibration factors can be determined and are entered into the acquisition system to correct the seabed level measurements in real-time.
12.2.5.1 Side Scan Sonar Survey
Prior to the commencement of the survey, the side scan sonar system was wet tested to ensure the system was working correctly. The equipment used in the survey is shown in the Image 1 of Appendix 12C.
The side scan sonar tow fish was towed from the stern of the survey vessel, at a depth of around 5m beneath the sea surface, depending on the water depth.
The recording parameters for the side scan survey were as follows:-
· Vessel speed: 1.5 – 1.8 m/sec
· Fix interval: 10 seconds
· Source frequency: 100 kHz and 500 kHz
· Pulse length: 25 us
· Gain setting: Manually controlled
· Slant range: 75m
All data were logged on the C-view SDMP where four channels (100kHz port and starboard; 500kHz port and starboard) were simultaneously recorded with navigation, fix, vessel heading, cable out angle and length, fish heading, water depth.
Detailed log sheets were recorded with unique survey line numbers, start fix and end fix for each survey line, roll number, range, frequency and cable out value and angle. The corresponding C-View data file name was also recorded in these log sheets.
12.2.5.2 Seismic Reflection Survey
Prior to the commencement of survey the EGS boomer was wet tested to ensure the system was working correctly. The EGS boomer was towed from the stern of the survey vessel, at a distance of 20m such that noise from the survey vessel was kept to a minimum. The recording system used in the survey is shown in Image 2 of Appendix 12C.
The recording parameters for the seismic reflection survey were as follows:
· Vessel Speed: 1.5 – 1.8 m/sec
· Fix Interval: 10 seconds
· Out put power: +/- 500 volts
· Sweep: 80ms (paper)
· Delay: 0ms
· Gain setting: Manually controlled
Safety was generally in accordance with the 'Marine Geophysical Operations Safety Manual' (International Association of Geophysical Contractors, Ninth Edition, 2004).
Quality was assured by adopting the measures set out in the EGS ISO9001 Quality Handbook.
12.2.8 Reduction of Observations and Interpretation
12.2.8.1 Sounding and Swath (Multibeam) Data
For sounding readings, the influence of wave action was corrected in real time by the heave motion compensator. The smoothed sounding data was then reduced to levels below Principal Datum (PD) using the measured tide levels.
Tidal correction and filters were applied before the swath data sets were edited manually. Gridded sounding selection was used for engineering purposes. These gridded data were then plotted at a spacing of 6mm at the charting scale, to provide a sounding plan for the whole area surveyed This gridded plot was contoured using the 2m spacing dataset and coloured using processing and charting software to provide the sounding plans.
Processing and interpretation of side scan sonar data was carried out using the C-View interpretation software. All features were individually marked or grouped into regions using on- screen digitising. All offsets and laybacks were applied to the C-View system. The subsequently generated interpretation files were then imported to the Auto CAD environment on a line by line basis where the interpretation was reconciled and a detailed check was performed.
12.2.9 Diver Survey
The Underwater Inspection was carried out between 7th and 12th May 2009. The dive platform was a commercially licenced boat shown in Figure 12.2. SDA Marine Ltd directed a team of four divers supplied by Bekks solutions Ltd. All the divers hold HSE qualifications and diving was conducted with strict safety considerations. Each diver used surface supplied air and through water communications thereby enabling verbal contact with the dive supervisor at all times. A video recording of all time spent underwater was achieved by a helmet mounted video camera using the BP-DVIS Diver Video Inspection Unit as shown in Figure 12.2. The dive supervisor and marine archaeologist were able to monitor and direct the work of the diver at all times and view his activity on the surface television monitor.
A hand held GPS was used to relocate the position of the sonar contacts. Once on location, a 25-kg metal sinker was placed on the seabed at the fix point and a 5m, 15m and 20m radius sector seabed inspection completed by the diver. The principle of the search is that the diver extends the line to the set length and searches radially about the centre point. If any objects are present, the line will snag everything within the circumference of the search area. This approach ensured 100% seabed coverage despite restricted through water visibility. In addition, the diver used a hand held metal rod of 1.5m length to probe the seabed every 2m. Figure 12.2 shows the diver with metal probe and search rope. The aim of the probe was to locate buried objects and establish the density of the seabed sediments. Continuous video footage of every dive was obtained.
The aim of the baseline review is to
compile the most significant information to establish the archaeological
potential of the seabed within the study area. It is not an exhaustive
chronological history of the area. Only incidents and information relevant to
the current study are included.
12.3.1.1
Archaeological
Investigation on Chek Lap Kok
The first
archaeologist to examine sites on the island was Walter Schofield, whose
notebooks recorded that he visited Chek Lap Kok on at least four occasions in 1923, 1925, 1931 and
1933. Additional Neolithic stone and pottery artefacts were found during
the 1950’s by members of the University Archaeological Team, the predecessor of
the Hong Kong Archaeological Society.
When the
possibility of opening a new airport was first discussed in 1979, the Archaeological
Society began a series of excavations on the sand bar site at Sham Wan Tsuen. This work yielded evidence of occupation
during the late Tang (唐) and Song (宋) Dynasties and also during the
Neolithic (Meacham, 1994).
After the
final decision was made to proceed with the airport, the Hong Kong
Archaeological Society was commissioned to organise a major archaeological
rescue project with funds provided by the Royal Hong Kong Jockey Club. A
sixteen month study of the history and archaeology of the island was completed
including ten months of survey and excavation followed by analysis of the
materials discovered and research on the history of the island.
During the
project four major sites were excavated:-
·
Fu Tei Wan (虎地灣): main deposit on a plateau with
occupation during the Middle Neolithic Period dating to 4000-3300 BC;
·
Ha Law Wan (蝦螺灣): discovery of a Yuan (元) Dynasty kiln complex probably
associated with the smelting of iron ore;
·
Kwo Lo Wan (過路灣):
middle Neolithic deposit on hill slope and Bronze Age material with burials
just behind the beach; and
·
Sham Wan Tsuen (深灣村): a major Tang Dynasty lime kiln
site was excavated. Late Neolithic and Han (漢) Dynasty materials were also
recovered.
An unexpected
result of the investigation was the discovery of remains of almost every phase
of
Although
construction of the airport resulted in the destruction of most of the
archaeological sites the kiln complex at Ha Law Wan was preserved within the
conservation area of the airport. The Tang Dynasty lime kiln at Fu Tei Wan was re-located to Tung Chung by the Gurkha Engineers where accessible to the public.
12.3.1.2
Historical
Background of Chek Lap Kok
The
The first
reference to the island in western sources is a brief mention in a British
naval reconnaissance report by Lt. H.W. Parrish in 1794. He was part of a small survey expedition on a quest to
identify suitable anchorages:
‘intended
to protect the large and valuable ships of the
Bad weather
restricted their movements but they made a brief reconnaissance of Chek Lap Kok the details of which
are recorded in the log of the voyage:
“The
The officer who sounded in the boat, reported his having seen
boats pass through the Tung Chung channel and that the land in its
neighbourhood on Lantau was ‘low and cultivated’ (Cranmer-Byng &
Shepherd 1964).
This is a
very valuable contemporary description of Chek Lap Kok as it indicates that it was not a well known anchorage
in 1794 and that there was evidence of coastal occupation on Lantau.
The first detailed
evidence of human occupation on the island from written sources is the land use
survey carried out in 1904-5 by British Army Indian surveyors, as part of the
general registration of land ownership in the
Some
fishermen made use of the coastal area for repairing their boats and for drying
their fishing nets. On the north coast of the island there was a Tin Hau temple built in 1823. The temple was built of
granite with money donated by some quarry companies.
After World
War II, the quarrying activity declined and many people moved to the city for
better employment. By the 1950s, only about two hundred people lived on
the island.
12.3.1.3
Maritime
Activity in the Vicinity of Tung Chung
During the
12th century there was a 50 year rebellion on
Lantau as the Government sought to control fishing and salt working
activities. It is recorded in the 1819 gazetteer of Xin’an
(新安) that there was an attempt in 1197
to stop private salt trading in Lantau. The
islanders successfully repulsed a government invasion force by mining their
harbours with stakes and engaging them in a sea battle. They captured
merchant ships and killed more than three hundred people. Tung
Chung is very likely to have been one of the harbours involved in the battle (
Tung Chung
is also associated with one of the most famous pirate battles in the history of
Glasspoole had been captured on 7
September 1809 while returning to his ship from a trip to
Glasspoole’s account was
written shortly after the battle for his local masters, the Select Committee of
Supercargoes of the East India Company in Macau, and published in
There is another
contemporary description of the battle which was translated in 1831 and
published in
“ … In
consequence of this determination all commanders and officers of the different
vessels were ordered to meet on the seventeenth at Chek
Lap Kok, to blockade the pirates in Ta Yu Shan, and
to cut off all supplies of provisions that might be sent to them. To
annoy them yet more, the officers were ordered to prepare the materials for the
fire-vessels. These fire-vessels were filled with gunpowder, nitrate and
other combustibles; after being filled, they were set on fire by a match from
the stern, and were instantly all in a blaze. The Major of Heang Shan, Pang Noo, asked
permission to bring soldiers with him, in order that they might go ashore and
make an attack under the sound of martial music, during the time the mariners
made their preparation.
On the
twentieth it began to blow very fresh from the north, and the commander ordered
twenty fire-vessels to be sent off, when they took driven by the wind, an
easterly direction; but the pirates’ entrenchments being protected by a
mountain, the wind ceased, and they could not move father on in that direction;
they turned about and set on fire two men of war. The pirates knew our
design and were well prepared for it; they had bars with very long pincers, by
which they took hold of the fire-vessels and kept them off, they that they
could not come near. Our commander, however, would not leave the place;
and being very eager to fight, he ordered that an attack should be made, and it
is presumed that about three hundred pirates were killed. Pao (i.e.Cheung Po Tsai) now
began to be afraid, and asked the Spirit of the Three
There arose
with the daylight on the twenty-second a light southerly breeze; all the
squadrons began to move, and the pirates prepared themselves to joyfully leave
their station. About noon, there was a strong southerly wind, and a very rough sea on. As soon as it became
dark the pirates made sail, with a good deal of noise, and broke through the
blockade, favoured by the southerly wind. About a hundred vessels were
upset, when the pirates left Ta Yu Shan. But our commander being unaware
that the pirates would leave their entrenchments was not prepared to withstand
them. The foreign vessels fired their guns and surrounded about ten leaky
vessels, but could not hurt the pirates themselves; the pirates left the leaky
vessels behind and ran away”
Whatever the
truth of the details of the battle, there is no question that at the end of the
nine day battle the pirates were not defeated. However Cheung Po Tsai
eventually surrendered in 1810 to the Viceroy Bailing
of the Qing navy. At the time of surrender he had over 270 junks, 16,000
men, 5,000 women, 7,000 swords and 1,200 guns (Cortesão,
1944.). These figures clearly indicate the scale of the pirate activities
in the region.
A remarkable 18m long Qing scroll painted on silk depicts the actions of
the Viceroy Bailing (c.1748-1816) from his assumption to office in 1809 to the successful solution to the piracy problem in the summer of
1810. It is divided into twenty ‘episodes’ and includes the pirate battle at Tung
Chung. The scroll is currently displayed in the
During the dredging of the seabed between Chek Lap Kok and Tung Chung for
the new airport in 1993, part of a cannon and a cannon ball were discovered and reported to the Provisional Airport
Authority (Image 4 of Appendix 12C). An inscription on the cannon
reveals that it was manufactured around 1808 in
With the
surrender of the pirates in 1810, the inhabitants of Lantau and Chek Lap Kok were able to live in
peace and continue their intensive farming and quarrying. The large
amount of granite produced on the island favoured the development of granite
quarrying. The products were used to build roads and houses in the
developing city of
The modern
period saw the northern part of Lantau remain relatively undeveloped. The
advent of steam power meant that fewer trading vessels needed to take refuge in
the safe anchorage provided by Tung Chung. Additional the ever increasing draft
of modern vessels meant that the shallow waters of the approach to Tung Chung
and the bay itself precluded the settlement from becoming a port of call and
commercial centre, The incorporation of Lantau into the New Territories in 1898
resulted in the departure of the garrison and seven or eight war junks as well
as their supply vessels.
12.3.1.4
The
Tung Chung Walled City
The
disruption and danger posed by the pirates led to the building of the Tung
Chung walled city, also called the Tung Chung Fort. It was built on a piece of
land between Sheung Ling Pei(上嶺皮) and Ha Ling Pei (下嶺皮) villages in the
The walled city
backs up against the Tai Tung mountain. Its four
rubble filled walls enclose an area of 225 feet by 265 feet and the more
formidable front wall runs to about 15 feet thick. Along the main wall
can be seen six old muzzle loading cannons each fixed to a cement base. There
are two on the western side and four on the eastern side. They bear
inscriptions but only four out of the six are still legible. They detail
the casting of each cannon: for example the inscription on the second one
from the east states that it was cast in the 8th moon of the 14th
year of the Jiaqing (嘉慶) reign (1809), serial number Qing
80, weighing 1,000 catties and was cast by the master of the Man Shing Furnace.
At this time
the pirate Cheung Po Tsai had a very strong influence on
Two further
cannons are dated to 1841 and were probably used for defence against the
British and the opium traders (Image 5 of Appendix
12C). On the eastern side of the
main gate one of the cannons was cast in the 1st moon of the 10th year of the Jiaqing reign (1805) and weighs 1,200 catties. It is
highly likely that this cannon was also used for the
defence of the region against piracy. The cannon lying next to the one
above has been severely weathered and its inscription is illegible. It is clear
from the differing casting dates that the cannons were cast elsewhere and
transported. Although they have been cast over a period of 4 decades they
all shared the same purpose of defending the region against pirates and foreign
invaders. The walled city (also known as Tung Chung Fort) has been
declared a monument and has been extensively repaired and it now opens as a
visitor attraction.
12.3.1.5
Tung
Chung Battery (東涌小炮台)
Further
evidence for the severity of the pirate threat is demonstrated by the presence
of Tung Chung Battery (Image 6 of Appendix
12C). Tung Chung is in a
valley surrounded by hills on three sides and faces the sea to the north. The
valley is well drained by streams and provides fertile land for farming. As the
entrance to Tung Chung a low lying hill known as the Shek She Shan (the rocky lion
mountain) is situated. The Tung Chung Battery is found on the mountain’s north slope.
The Tung
Chung Battery was built in 1817 in order to strengthen defences on the northern
coast of
12.3.1.6
Summary
of Archaeological Potential
The density
of archaeological remains on the former
However, it
is highly unlikely that there will be prehistoric archaeological remains on the
seabed at this location. Across the study area the Marine Deposit is a minimum
of 18m thick. The Marine Deposit has been locally classified as the Hang Hau Formation and dated from 7,960 yBP
to 2,170 yBP (Fyfe, J.A., Shaw, R. 1997). It is
composed of soft olive-grey clayey to sandy silt with shell debris scattered
throughout. Any evidence for human occupation during the pre-Holocene would be
beneath this layer at the interface with the alluvium. Archaeological
remains would therefore be buried beneath a substantial thickness of soft
marine mud. Tung Chung has documented maritime
history of sea battles and pirate infestation. The fort and battery built
to defend against the pirates are still in-situ at Tung Chung and can be
visited. The pirate sea battle in particular would give the seabed in the study
area high archaeological potential. However, the archaeological potential
is significantly reduced due to Chek Lap Kok airport and the seabed disturbance which occurred
during its construction. The geophysical survey data has indicated extensive
seabed disturbance.
The UK Hydrographic Office (UKHO)
holds a database of surveyed shipwrecks in
The UKHO holds charts of the study
area including the French Admiralty for 1856 (Image 7 of Appendix
12C) and the British Admiralty Chart
1899 Image 8 Appendix 12C).
The database contained no records of
shipwrecks within the study area.
The
interpretation of the side scan sonar records in this area had sought to
quantify the following elements and features on the seabed:-
·
Indicators
for the presence of intact or broken up shipwrecks;
·
Isolated
objects which could have archaeological potential;
·
Areas of
disturbed seabed attributed to anchoring or trawling;
·
Large area of debris, dumped materials or
concrete slabs;
·
Seafloor
with pipeline/cable related scars;
·
Higher reflectivity areas attributed to
gravel or sandy materials and rocks;
·
Lower
reflectivity areas attributed to relatively clean or undisturbed marine
sediments; and
·
Any other significant sonar contacts.
Although there are masked zones over
the north boundary and south portion of the survey area, the quality of the
seismic records was good and acceptable.
Interpretation
of the Geological Succession
The interpretation of the seismic
records sought to quantify the following elements of the offshore geological
succession:-
Table 12-3 Interpretation of Seismic Records
|
FORMATION |
EVENT |
|
Marine Deposits of Holocene age (Hang Hau Formation) |
The base of these deposits occurred during the last ice age |
|
Alluvium (Chek
Lap Kok Formation; mainly coarse sediments with
gravels) |
Up to four ice ages occurred during the Pleistocene |
|
The top of rock in some state of decomposition |
N/A |
|
Grade III rock |
N/A |
The main
components of the seabed stratigraphy
are presented in Image 9 of Appendix 12C.
Marine
Deposits are generally soft or very soft clays or silts, and as such are
readily identifiable on seismic records as a clear conformable horizon
sometimes with an unconformity represented by a desiccated layer or by local re-working of deposits by ancient
river systems.
Interpretation was carried out as
follows:-
The seismic horizons were selected
for interpretation in accordance with the list above, and drawn on copies of
the seismic records during preliminary interpretation. All
traverse crossing points were then calculated, and marked on the seismic records. The records were then
physically correlated at all of these points and the horizons digitized,
plotted and contoured.
12.3.3.2
Organic Masking / Presentation /Plot Drawings
Organic Masking
Seismic data interpretation has revealed a
significant masked areas east of Chek Lap Kok within the survey boundary. This is probably caused by the
presence of organic materials on the seabed (e.g. discharge from the airport)
and anaerobic bacteria feeding on decaying organic material at depth. The gas
bubbles so generated absorb the seismic energy, thereby preventing reflections
from deeper horizons.
The results
have been presented in summary plots. The geophysical survey covered the
study areas for both the HKBCF and the Tuen Mun-Chek Lap Kok Link. Only
the data relevant to the HKBCF is included in this report which explains why the
plots do not include all the plots drawings in the sequence.
Plot Drawings (See Appendix 12D)
·
Plots 1.3,
1.4, 1.5
Echo Sounding and Swath Bathymetry Track Plots
·
Plots 2.3,
2.4,
2.5
Seismic and Side Scan Sonar Track Plots
·
Plots 4.3,
4.4,
4.5
Colour Contoured Swath Bathymetry Plans
·
Plots 5.3,
5.4,
5.5
Contoured Levels at the Base of Marine Deposits
·
Plots 6.3,
6.4,
6.5
Contoured Levels on Top of Rock in Any State of
·
Plots 7.3,
7.4,
7.5
Contoured Levels on Top of Presumed Moderately Decomposed Rock
·
Plots 8.3,
8.4,
8.5 Isopachs of Marine Deposits
·
Plots 9.3,
9.4,
9.5 Isopachs of Alluvium
·
Plots 10.3,
10.4, 10.5 Isopachs
of Rock in Any State of
·
Plots 11.3,
11.4, 11.5 Sea Bed Features and Cable
Alignments
The plots
show the exact area of seabed covered by each piece of equipment.
Table 12-4 Interpretation of Track Records
|
POSITION/TRACK TYPE |
DEFINITION |
|
Echo sounding and swath bathymetry track |
This is the track of the echo sounder and swath
header, used to define sea bed levels |
|
Seismic and side scan track |
Seismic and side scan surveys have been
conducted simultaneously, hence tracks of seismic data are presented here for
presentation purposes |
Colour Contoured Bathymetry Plan (Plots
4.3, 4.4, 4.5 of Appendix 12D)
Seabed level
readings are presented in the drawings at 15m grids (6mm in chart scale).
Bathymetric data collected by swath system are shown in colour contoured
format, while seabed levels from echo sounder are shown in non-colour lines.
The seabed
varies between –2m PD and –11m PD within the survey area.
12.3.3.3
Marine
Deposits (Plots 5.3, 5.4, 5.5 of Appendix 12D)
The drawings
illustrate the general topographic levels at the base of the Marine
Deposits.
Within the
footprint of the HKBCF there is a layer of Marine Deposit. Close to the
coast near CLK its minimum thickness is 18m increasing to 28m in the northern section
of the study area.
12.3.3.4
Alluvium
(Plots 6.3, 6.4, 6.5 of Appendix 12D)
Isopachs of Alluvium are presented on Images
9.3 to 9.5. The survey results show that alluvium over the survey area is
mostly more than 6m thick.
12.3.3.5
Rock
in Any State of
The
topographic variation of the base of rock in any state of decomposition
corresponds to the top of moderately decomposed rock.
12.3.3.6
Sea bed Features (Plots 11.3, 11.4, 11.5 of Appendix
12D)
As shown on
the drawings, sandy clays and silts are common features on the seabed, with
numerous trawl marks, anchor scars, and scattered modern debris.
Image 10 of Appendix 12C
is a copy of the side scan sonar data showing evidence of seabed disturbance
caused by anchors.
12.3.3.7
Cable Alignments (Plots 11.3, 11.4, 11.5 of Appendix
12D)
Four
submarine cables run through the study area. These are important for the
MAI as they represent areas of previous disturbance.
Image 11 of Appendix 12C is a copy of side scan sonar data
showing the seabed disturbance caused by cable installation.
12.3.3.8
Areas
of Archaeological Potential
Three sonar
contacts with archaeological potential were identified from the side scan sonar
survey data. On the seabed features Plots 11.3 and 11.5 of Appendix 12D
the sonar contacts have been classified as debris by EGS. Within a busy
shipping area with evidence of recent seabed disturbance, the survey classification
of debris is logical and appropriate for the Site Investigation report.
However, from an archaeological perspective these targets could be contemporary
debris from modern vessels or artefacts of historical significance.
Seismic
profiler data showing the sonar contacts is not available as all three are
located in areas where data was adversely affected by sediment masking.
Careful
examination of the side scan sonar records does not provide evidence for intact
shipwrecks. It is more likely that each of the targets is an isolated object or
a shipwreck which has been broken up by previous disturbance, such as trawling.
Figure 12.1
presents the location of each sonar contact in relation to the HKBCF layout.
The details of each contact are presented in the table below and the side scan
sonar data showing each one is presented as Images 12, 13 & 14 of Appendix 12C.
Table 12-5 Sonar Contacts with Archaeological Potential
|
SONAR
CONTACTS WITH ARCHAEOLOGICAL POTENTIAL |
|||
|
Contact
Number |
Easting
Northing |
Dimensions
(m) |
Distance
from BCF |
|
SC006 |
812594.0E |
1.7
x 1.3 x nmh* |
10.8 |
|
SC010 |
813205.2E |
1.4
x 0.8 x 0.4 |
114.2 |
|
SC011 |
812981.7E |
1.4
x 2.0 x 0.3 |
19.6 |
*Note: nmh = no
measurable height
12.4 Impact Assessment
Figure 12.3 shows the proposed layout of the HKBCF and the areas where dredging and reclamation will take place. It is assumed that during Phase I construction, dredging will be carried out at Portions A, B, D. The rescue berth and the proposed dredged seawall would destruct the archaeological resources, if present. Phase 2 construction comprising fully dredged seawall and dredging of the underground APM would also impact on archaeological resources, if present.
There would be less impact in the area of the non-dredged seawall but this area would be indirectly impacted by the activities of the barges required for the dredging and reclamation. In the non-dredged areas where there will be reclamation, the seabed would be impacted by the installation of the band drains.
Figure 12.4 is a cross section through the seabed at the proposed BCF presenting the depths of reclamation and dredging.
12.4.1 Diver Survey
The diver survey successfully located and indentified all three of the sonar contacts. Each of them was easily identified as modern debris:
· SC006 Metal pole
· SC010 Concrete block with marine growth
· SC011 Canvas strap and building debris
Figure 12.5 is still photographs taken from the video footage of each object . The quality of the images is poor due to the high sedimentation.
The hand held probe used by the divers did not locate any buried objects. The seabed at this location is extremely disturbed due to the impact of the airport construction. The diver inspection at this area also confirmed that the seabed is regularly trawled. This activity would serve to either destroy or redistribute archaeological resources. The seabed in this area is characterised by an almost total absence of marine life which is further evidence for the trawling activities.
12.5 Recommendation
The diver survey located and identified each of the sonar contacts as modern debris and confirmed the extent of previous seabed disturbance. It is therefore concluded that there is no underwater cultural heritage within the study area.
There is no need for any further investigation or mitigation measures
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