Contract No.
HY/2011/03
Hong Kong-Zhuhai-Macao Bridge Hong Kong Link
Road
Section between Scenic Hill and Hong Kong Boundary Crossing
Facilities
Monthly EM&A Report No.99 (December 2020)
14 January 2021
Revision
1
Main
Contractor Designer
Contents
Executive Summary
1.4 Construction
Works Undertaken During the Reporting Month
2....... Air Quality Monitoring
2.4 Monitoring
Parameters, Frequency and Duration
2.6 Monitoring
Schedule for the Reporting Month
3.4 Monitoring
Parameters, Frequency and Duration
3.6 Monitoring
Schedule for the Reporting Month
4....... Water
Quality Monitoring
4.3 Monitoring
Parameters, Frequency and Duration
4.6 Monitoring
Schedule for the Reporting Month
6.1 Sedimentation
Rate Monitoring
6.3 Mudflat Ecology Monitoring Methodology
6.4 Event and Action Plan for Mudflat Monitoring
6.5 Mudflat Ecology Monitoring Results and Conclusion
7....... Environmental Site
Inspection and Audit
7.2 Advice
on the Solid and Liquid Waste Management Status
7.3 Environmental
Licenses and Permits
7.4 Implementation
Status of Environmental Mitigation Measures
7.5 Summary
of Exceedances of the Environmental Quality Performance Limit
7.6 Summary
of Complaints, Notification of Summons and Successful Prosecution
8.1 Construction
Programme for the Coming Months
8.2 Environmental
Monitoring Schedule for the Coming Month
Figures
Figure 1.1 Location of the Site
Figure 2.1 Environmental Monitoring Stations
Figure 2.2
Transect Line Layout in Northwest and Northeast Lantau Survey Areas
Figure 6.1 Mudflat
Survey Areas
Appendices
Appendix A Environmental
Management Structure
Appendix B Construction
Programme
Appendix C Calibration
Certificates
Appendix D Monitoring
Schedule
Appendix E Monitoring
Data and Graphical Plots
Appendix F Event
and Action Plan
Appendix I Mudflat
Monitoring Results
Appendix K Cumulative
Statistics on Complaints
Appendix L Environmental
Licenses and Permits
Appendix M Implementation
Schedule of Environmental Mitigation Measures
Appendix N Record
of ¡§Notification of Summons and Prosecutions¡¨
Appendix O Location
of Works Areas
Executive Summary
The Hong Kong-Zhuhai-Macao
Bridge (HZMB) Hong Kong Link Road (HKLR) serves to connect the HZMB Main Bridge
at the Hong Kong Special Administrative Region (HKSAR) Boundary and the HZMB
Hong Kong Boundary Crossing Facilities (HKBCF) located at the north eastern
waters of the Hong Kong International Airport (HKIA).
The HKLR project has been
separated into two contracts. They are Contract No. HY/2011/03 Hong
Kong-Zhuhai-Macao Bridge Hong Kong Link Road-Section between Scenic Hill and Hong
Kong Boundary Crossing Facilities (hereafter referred to as the Contract) and
Contract No. HY/2011/09 Hong Kong-Zhuhai-Macao Bridge Hong Kong Link
Road-Section between HKSAR Boundary and Scenic Hill.
China State Construction
Engineering (Hong Kong) Ltd. was awarded by Highways Department as the
Contractor to undertake the construction works of Contract No. HY/2011/03. The main works of the Contract include
land tunnel at Scenic Hill, tunnel underneath Airport Road and Airport Express
Line, reclamation and tunnel to the east coast of the Airport Island, at-grade
road connecting to the HKBCF and highway works of the HKBCF within the Airport
Island and in the vicinity of the HKLR reclamation. The Contract is part of the HKLR Project
and HKBCF Project, these projects are considered to be ¡§Designated Projects¡¨,
under Schedule 2 of the Environmental Impact Assessment (EIA) Ordinance (Cap
499) and Environmental Impact Assessment (EIA) Reports (Register No.
AEIAR-144/2009 and AEIAR-145/2009) were prepared for the Project. The current Environmental Permit (EP)
EP-352/2009/D for HKLR and EP-353/2009/K for HKBCF were issued on 22 December
2014 and 11 April 2016, respectively. These documents are available through the
EIA Ordinance Register. The construction phase of Contract was commenced on 17 October 2012.
BMT Hong Kong Limited was
appointed by the Contractor to implement the Environmental Monitoring & Audit
(EM&A) programme for the Contract in accordance with the Updated EM&A
Manual for HKLR (Version 1.0) and provided environmental team services to the
Contract until 31 July 2020.
This is the ninety-ninth Monthly
EM&A report for the Contract which summarizes the monitoring results and
audit findings of the EM&A programme during the reporting period from 1 to 31
December 2020.
Environmental
Monitoring and Audit Progress
The monthly EM&A
programme was undertaken in accordance with the Updated EM&A Manual for
HKLR (Version 1.0). A summary of the monitoring activities during this
reporting month is listed below:
1-hr TSP Monitoring |
1, 7, 11, 17, 23 and 29 December 2020 |
24-hr TSP Monitoring |
4, 10, 16, 22 and 28 December 2020 |
Noise Monitoring |
1, 7, 17, 23 and 29 December 2020 |
Water Quality Monitoring |
Not applicable. Water
quality monitoring was temporarily suspended during the reporting month. |
Chinese White Dolphin
Monitoring |
Not applicable. Dolphin
monitoring was temporarily suspended during the reporting month. |
Site Inspection |
2, 9, 16, 23
and 29 December 2020
|
Mudflat Monitoring
(Ecology) |
10, 11, 15 and 16
December 2020
|
Mudflat Monitoring
(Sedimentation Rate) |
7 December 2020
|
Breaches of Action and Limit Levels
A summary of environmental
exceedances for this reporting month is as follows:
Environmental Monitoring |
Parameters |
Action Level (AL) |
Limit Level (LL) |
Air Quality |
1-hr TSP |
0 |
0 |
24-hr TSP |
0 |
0 |
|
Noise |
Leq (30 min) |
0 |
0 |
Water Quality |
Suspended solids level (SS) |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
Turbidity level |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
|
Dissolved oxygen level (DO) |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
Remark: 1) Not applicable. Water
quality monitoring was temporarily suspended during the reporting month.
Complaint Log
There was no complaint
received in relation to the environmental impacts during this reporting month.
Notifications
of Summons and Prosecutions
There were no
notifications of summons or prosecutions received during this reporting month.
Reporting
Changes
This report has been
developed in compliance with the reporting requirements for the subsequent
EM&A reports as required by the Updated EM&A Manual for HKLR (Version
1.0).
The proposal for the change
of Action Level and Limit Level for suspended solid and turbidity was approved
by EPD on 25 March 2013.
The revised Event and
Action Plan for dolphin monitoring was approved by EPD on 6 May
2013.
The original monitoring
station at IS(Mf)9 (Coordinate: 813273E, 818850N) was
observed inside the perimeter silt curtain of Contract HY/2010/02 on 1 July
2013, as such the original impact water quality monitoring location at IS(Mf)9 was temporarily shifted outside the silt curtain. As advised by the Contractor of HY/2010/02 in August 2013, the perimeter
silt curtain was shifted to facilitate safe anchorage zone of construction
barges/vessels until end of 2013 subject to construction progress. Therefore, water quality monitoring
station IS(Mf)9 was shifted to 813226E and 818708N
since 1 July 2013. According to the
water quality monitoring team¡¦s observation on 24 March 2014, the original
monitoring location of IS(Mf)9 was no longer enclosed
by the perimeter silt curtain of Contract HY/2010/02. Thus, the impact water
quality monitoring works at the original monitoring location of IS(Mf)9 has been resumed since 24 March 2014.
Transect lines 1, 2, 7, 8,
9 and 11 for dolphin monitoring have been revised due to the obstruction of the
permanent structures associated with the construction works of HKLR and the
southern viaduct of TM-CLKL, as well as provision of adequate buffer distance
from the Airport Restricted Areas.
The EPD issued a memo and confirmed that they had no objection on the
revised transect lines on 19 August 2015.
The water quality
monitoring stations at IS10 (Coordinate: 812577E, 820670N) and SR5 (811489E,
820455N) are located inside Hong Kong International Airport (HKIA) Approach
Restricted Areas. The previously granted Vessel's Entry Permit for accessing
stations IS10 and SR5 were expired on 31 December 2016. During the permit
renewing process, the water quality monitoring location was shifted to IS10(N)
(Coordinate: 813060E, 820540N) and SR5(N) (Coordinate: 811430E, 820978N) on 2,
4 and 6 January 2017 temporarily. The permit has been granted by Marine
Department on 6 January 2017. Thus, the impact water quality monitoring works
at original monitoring location of IS10 and SR5 has been resumed since 9
January 2017.
Transect lines 2, 3, 4, 5,
6 and 7 for dolphin monitoring have been revised and transect line 24 has been
added due to the presence of a work zone to the north of the airport platform
with intense construction activities in association with the construction of
the third runway expansion for the Hong Kong International Airport. The EPD
issued a memo and confirmed that they had no objection on the revised transect
lines on 28 July 2017. The alternative dolphin transect lines are adopted starting
from August¡¦s dolphin monitoring.
The role and responsibilities as the ET Leader of the Contract was temporarily
taken up by Mr Willie Wong instead of Ms Claudine Lee from 25 September 2017 to 31 December 2017.
The topographical condition of the water monitoring
stations SR3 (Coordinate: 810525E, 816456N), SR4 (Coordinate: 814760E, 817867N),
SR10A (Coordinate: 823741E, 823495N) and SR10B (Coordinate: 823686E, 823213N) cannot
be accessed safely for undertaking water quality monitoring. The water quality
monitoring has been temporarily conducted at alternative stations, namely
SR3(N) (Coordinate 810689E, 816591N), SR4(N) (Coordinate: 814705E, 817859N) and
SR10A(N) (Coordinate: 823644E, 823484N) since 1 September 2017. The water
quality monitoring at station SR10B was temporarily conducted at Coordinate:
823683E, 823187N on 1, 4, 6, 8 September 2017 and has been temporarily
fine-tuned to alternative station SR10B(N2) (Coordinate: 823689E, 823159N)
since 11 September 2017. Proposal for permanently relocating the aforementioned
stations was approved by EPD on 8 January 2018.
The works area WA5
was handed over to other party on 22 June 2013.
According to
latest information received in July 2018, the works area WA7 was handed over to
other party on 28 February 2018 instead of 31 January 2018.
Original WQM stations IS8 and SR4(N) are located
within the active work area of TCNTE project and the access to the WQM stations
IS8 (Coordinate: E814251, N818412) and SR4(N) (Coordinate: E814705, N817859)
are blocked by the silt curtains of the Tung Chung New Town Extension (TCNTE)
project. Alternative monitoring stations IS8(N) (Coordinate: E814413, N818570)
and SR4(N2) (Coordinate: E814688, N817996) are proposed to replace the original
monitoring stations IS8 and SR4(N). Proposal for permanently relocating the
aforementioned stations was approved by EPD on 20 August 2019. The
water quality monitoring has been conducted at stations IS8(N) and SR4(N2) on
21 August 2019.
There were no marine works conducted by
Contract No. HY/2011/03 since July 2019. A proposal for temporary suspension of
marine related environmental monitoring (water quality monitoring and dolphin
monitoring for the Contract No. HY/2011/03) was justified by the ET leader and
verified by IEC in mid of September 2019 and it was approved by EPD on 24
September 2019. Water quality monitoring and dolphin monitoring for the
Contract will not be conducted starting from 1 October 2019 until marine works
(i.e. toe loading removal works) be resumed. As discussed with Contract No. HY/2012/08,
they will take up the responsibility from Contract No. HY/2011/03 for the dolphin
monitoring works starting from 1 October 2019.
According to
information received in January 2020, the works area WA3 and WA4 were handed
over to Highways Department on 23 December 2019 and 14 March 2019 respectively.
The role and
responsibilities as the IEC of the Contract has been taken up by Mr Manson Yeung instead of Mr Ray Yan since 18 May 2020.
Mr. Leslie
Leung was Environmental Team Leader of the Contract for July 2020. The role and
responsibilities as the Environmental Team Leader of the Contract has been
taken up by Ms. Claudine Lee with effective from 1 August 2020.
The future key
issues include potential noise, air quality, water quality and ecological
impacts and waste management arising from the following construction activities
to be undertaken in the upcoming month:
¡P Landscaping works at Portion X and Airport Road;
¡P E&M works at Airport Road;
¡P
Finishing works for
Highway Operation and Maintenance Area (HMA) at Portion X;
¡P
Finishing works for
Scenic Hill Tunnel (SHT) Ventilation Building at West Portal; and
¡P
Extension of security
fencing at West Portal.
¡P
New reclamation along
the east coast of the approximately 23 hectares.
¡P
Tunnel of Scenic Hill
(Tunnel SHT) from Scenic Hill to the new reclamation, of approximately 1km in
length with three (3) lanes for the east bound carriageway heading to the HKBCF
and four (4) lanes for the westbound carriageway heading to the HZMB Main
Bridge.
¡P
An abutment of the
viaduct portion of the HKLR at the west portal of Tunnel SHT and associated
road works at the west portal of Tunnel SHT.
¡P
An at grade road on
the new reclamation along the east coast of the HKIA to connect with the HKBCF,
of approximately 1.6 km along dual 3-lane carriageway with hard shoulder for
each bound.
¡P
Road links between
the HKBCF and the HKIA including new roads and the modification of existing
roads at the HKIA, involving viaducts, at grade roads and a Tunnel HAT.
¡P
A highway operation
and maintenance area (HMA) located on the new reclamation, south of the Dragonair Headquarters Building, including the construction
of buildings, connection roads and other associated facilities.
¡P
Associated civil,
structural, building, geotechnical, marine, environmental protection,
landscaping, drainage and sewerage, tunnel and highway electrical and
mechanical works, together with the installation of street lightings, traffic
aids and sign gantries, water mains and fire hydrants, provision of facilities
for installation of traffic control and surveillance system (TCSS), reprovisioning works of affected existing facilities,
implementation of transplanting, compensatory planting and protection of
existing trees, and implementation of an environmental monitoring and audit
(EM&A) program.
Table 1.1 Contact
Information of Key Personnel
Party |
Position |
Name |
Telephone |
Fax |
Supervising
Officer¡¦s Representative |
(Chief Resident Engineer, CRE) |
Jackson Wong |
3968 4802 |
2109 1882 |
Environmental Project Office / Independent Environmental Checker |
Environmental Project Office Leader |
Y. H. Hui |
3465 2888 |
3465 2899 |
Independent Environmental Checker |
Manson Yeung |
3465 2806 |
3465 2899 |
|
Contractor |
Project Manager |
S. Y. Tse |
3968 7002 |
2109 2588 |
Environmental Officer |
Federick Wong |
3968 7117 |
2109 2588 |
|
Environmental Team (Meinhardt Infrastructure and Environment Limited) |
Environmental Team Leader |
Claudine Lee(1) |
2859 5409 |
2559 0738 |
24 hours complaint
hotline |
--- |
--- |
5699 5730 |
--- |
Notes:
(1)
The role and responsibilities as the Environmental Team Leader of the
Contract has been taken up by Ms. Claudine Lee with effective from 1 August 2020. |
Table 1.2 Construction Activities During Reporting Month
Description of Activities |
Site Area |
Landscaping
Works |
Portion X and Airport
Road |
E&M Works |
Airport Road |
Finishing
Works for Highway Operation and Maintenance Area Building |
Portion X |
Finishing
Works for Scenic Hill Tunnel Ventilation Building |
West Portal |
Extension
of Security Fencing |
West Portal |
Removal
of Temporary Bus Stop and Construction of Pedestrian Footpath |
Tung Yiu Road |
Table 2.1 Action and Limit
Levels for 1-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 ¡V Ma Wan Chung Village (Tung Chung) |
352 |
500 |
AMS 6 ¡V Dragonair / CNAC (Group) Building
(HKIA) |
360 |
Table 2.2 Action and Limit
Levels for 24-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 ¡V Ma Wan Chung Village (Tung Chung) |
164 |
260 |
AMS 6 ¡V Dragonair / CNAC (Group) Building
(HKIA) |
173 |
260 |
Table 2.3 Air Quality
Monitoring Equipment
Equipment |
Brand and Model |
Portable direct reading dust meter (1-hour
TSP) |
Sibata Digital Dust Indicator (Model No. LD-5R) |
High Volume Sampler |
Tisch Environmental Mass Flow Controlled
Total Suspended Particulate (TSP) High Volume Air Sampler (Model No. TE-5170) |
Table 2.4 Locations of Impact
Air Quality Monitoring Stations
Monitoring
Station |
Location |
AMS5 |
Ma Wan Chung Village (Tung Chung) |
AMS6 |
Dragonair / CNAC (Group) Building (HKIA) |
Table 2.5 Air
Quality Monitoring Parameters, Frequency and Duration
Parameter |
Frequency
and Duration |
1-hour TSP |
Three times every 6 days while the highest dust impact was expected |
24-hour TSP |
Once every 6 days |
(a) The HVS was installed in the vicinity of the air sensitive receivers.
The following criteria were considered in the installation of the HVS.
(i) A horizontal platform with appropriate support to secure the sampler
against gusty wind was provided.
(ii) The distance between the HVS and any obstacles, such as buildings, was
at least twice the height that the obstacle protrudes above the HVS.
(iii) A minimum of 2 meters separation from walls, parapets and penthouse for
rooftop sampler was provided.
(iv) No furnace or incinerator flues are nearby.
(v) Airflow around the sampler was unrestricted.
(vi) Permission was obtained to set up the samplers and access to the
monitoring stations.
(vii) A secured supply of electricity was obtained to operate the samplers.
(viii) The sampler was located more than 20 meters from any dripline.
(ix) Any wire fence and gate, required to protect the sampler, did not
obstruct the monitoring process.
(x) Flow control accuracy was kept within ¡Ó2.5% deviation over 24-hour
sampling period.
(b)
Preparation of Filter Papers
(i) Glass fibre filters, G810 were labelled and sufficient filters that were
clean and without pinholes were selected.
(ii)
All filters were equilibrated in the conditioning environment for 24
hours before weighing. The conditioning environment temperature was around
(iii)
All filter papers were prepared and analysed by ALS Technichem
(HK) Pty Ltd., which is a HOKLAS accredited laboratory and has comprehensive
quality assurance and quality control programmes.
(c) Field
Monitoring
(i) The power supply was checked to ensure the HVS works properly.
(ii) The filter holder and the area surrounding the filter were cleaned.
(iii) The filter holder was removed by loosening the four bolts and a new
filter, with stamped number upward, on a supporting screen was aligned
carefully.
(iv) The filter was properly aligned on the screen so that the gasket formed
an airtight seal on the outer edges of the filter.
(v)
The swing bolts were fastened to hold the filter holder down to the
frame. The pressure applied was
sufficient to avoid air leakage at the edges.
(vi) Then the shelter lid was closed and was secured with the aluminium
strip.
(vii) The HVS was warmed-up for about 5 minutes to establish run-temperature
conditions.
(viii) A new flow rate record sheet was set into the flow recorder.
(ix)
On site temperature and atmospheric pressure readings were taken and the
flow rate of the HVS was checked and adjusted at around 1.1 m3/min, and complied with the range specified in the Updated
EM&A Manual for HKLR (Version 1.0) (i.e. 0.6-1.7 m3/min).
(x) The programmable digital timer was set for a sampling period of 24
hours, and the starting time, weather condition and the filter number were
recorded.
(xi) The initial elapsed time was recorded.
(xii) At the end of sampling, on site temperature and atmospheric pressure
readings were taken and the final flow rate of the HVS was checked and
recorded.
(xiii)
The final elapsed time was recorded.
(xiv)
The sampled filter was removed carefully and folded in half length so that only surfaces with collected
particulate matter were in contact.
(xv)
It was then placed in a clean plastic envelope and sealed.
(xvi) All monitoring information was recorded on a standard data sheet.
(xvii) Filters were then sent to ALS Technichem (HK)
Pty Ltd. for analysis.
(d)
Maintenance and Calibration
(i) The HVS and its accessories were maintained in good working condition,
such as replacing motor brushes routinely and checking electrical wiring to
ensure a continuous power supply.
(ii) 5-point calibration of the HVS was conducted using TE
(iii) Calibration certificate of the HVSs are provided in Appendix C.
(a) Measuring Procedures
The measuring procedures of
the 1-hour dust meter were in accordance with the Manufacturer¡¦s Instruction
Manual as follows:-
(i)
Turn the power on.
(ii)
Close the air collecting opening cover.
(iii)
Push the ¡§TIME SETTING¡¨ switch to [BG].
(iv)
Push ¡§START/STOP¡¨ switch to perform background measurement for 6
seconds.
(v)
Turn the knob at SENSI ADJ position to insert the light scattering
plate.
(vi)
Leave the equipment for 1 minute upon ¡§SPAN CHECK¡¨ is indicated in the
display.
(vii)
Push ¡§START/STOP¡¨ switch to perform automatic sensitivity adjustment.
This measurement takes 1 minute.
(viii)
Pull out the knob and return it to MEASURE position.
(ix)
Push the ¡§TIME SETTING¡¨ switch the time set in the display to 3 hours.
(x)
Lower down the air collection opening cover.
(xi)
Push ¡§START/STOP¡¨ switch to start measurement.
(b) Maintenance
and Calibration
(i) The
1-hour TSP meter was calibrated at 1-year intervals against a Tisch
Environmental Mass Flow Controlled Total Suspended Particulate (TSP) High
Volume Air Sampler. Calibration certificates of the Laser Dust Monitors are
provided in Appendix C.
Table 2.6 Summary
of 1-hour TSP Monitoring Results During the Reporting Month
Monitoring Station |
Average (mg/m3) |
Range (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
AMS5 |
215 |
80 - 334 |
352 |
500 |
AMS6 |
160 |
90 - 360 |
360 |
500 |
Table 2.7 Summary of 24-hour TSP Monitoring Results During the
Reporting Month
Monitoring Station |
Average (mg/m3) |
Range (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
AMS5 |
84 |
67 - 121 |
164 |
260 |
AMS6 |
110 |
71 - 165 |
173 |
260 |
Table 3.1 Action
and Limit Levels for Noise during Construction Period
Monitoring Station |
Time Period |
Action Level |
Limit Level |
NMS5 ¡V Ma Wan Chung
Village (Ma Wan Chung Resident Association) (Tung Chung) |
0700-1900 hours on normal
weekdays |
When one documented complaint
is received |
75 dB(A) |
Table 3.2 Noise
Monitoring Equipment
Equipment |
Brand and Model |
Integrated Sound Level
Meter |
B&K 2238 |
Acoustic Calibrator |
B&K 4231 |
Table 3.3 Locations
of Impact Noise Monitoring Stations
Monitoring Station |
Location |
NMS5 |
Ma Wan Chung Village (Ma
Wan Chung Resident Association) (Tung Chung) |
Table 3.4 Noise
Monitoring Parameters, Frequency and Duration
Parameter |
Frequency and Duration |
30-mins measurement at
each monitoring station between 0700 and 1900 on normal weekdays (Monday to
Saturday). Leq, L10 and L90
would be recorded. |
At least once per week |
(a) The sound level meter was
set on a tripod at a height of
(b)
The battery condition was
checked to ensure the correct functioning of the meter.
(c)
Parameters such as
frequency weighting, the time weighting and the measurement time were set as
follows:-
(i) frequency
weighting: A
(ii) time weighting: Fast
(iii) time
measurement: Leq(30-minutes)
during non-restricted hours i.e. 07:00 ¡V 1900 on normal weekdays
(d)
Prior to and after each
noise measurement, the meter was calibrated using the acoustic calibrator for
94.0 dB(A) at 1000 Hz. If the
difference in the calibration level before and after measurement was more than
1.0 dB(A), the measurement would be considered invalid and repeat of noise
measurement would be required after re-calibration or repair of the equipment.
(e)
During the monitoring
period, the Leq, L10 and L90
were recorded. In addition, site
conditions and noise sources were recorded on a standard record sheet.
(f)
Noise measurement was
paused during periods of high intrusive noise (e.g. dog barking, helicopter
noise) if possible. Observations were recorded when intrusive noise was
unavoidable.
(g)
Noise monitoring was
cancelled in the presence of fog, rain, wind with a steady speed exceeding
(a) The microphone head of the sound level
meter was cleaned with soft cloth at regular intervals.
(b) The meter and calibrator
were sent to the supplier or HOKLAS laboratory to check and calibrate at yearly
intervals.
(c) Calibration certificates
of the sound level meters and acoustic calibrators are provided in Appendix C.
Table 3.5 Summary
of Construction Noise Monitoring Results During the Reporting Month
Monitoring Station |
Average Leq
(30 mins), dB(A) |
Range of Leq
(30 mins), dB(A) |
Limit Level Leq
(30 mins), dB(A) |
NMS5 |
58 |
55 - 63 |
75 |
Table 4.1 Action
and Limit Levels for Water Quality
Parameter (unit) |
Water Depth |
Action Level |
Limit Level |
Dissolved Oxygen (mg/L)
(surface, middle and bottom) |
Surface and Middle |
5.0 |
4.2 except 5 for Fish
Culture Zone |
Bottom |
4.7 |
3.6 |
|
Turbidity (NTU) |
Depth average |
27.5 or 120% of upstream
control station¡¦s turbidity at the same tide of the same day; The action level has been
amended to ¡§27.5 and 120% of upstream control station¡¦s turbidity at the same
tide of the same day¡¨ since 25 March 2013. |
47.0 or 130% of turbidity
at the upstream control station at the same tide of same day; The limit level has been amended
to ¡§47.0 and 130% of turbidity at the upstream control station at the
same tide of same day¡¨ since 25 March 2013. |
Suspended Solid (SS)
(mg/L) |
Depth average |
23.5 or 120% of upstream
control station¡¦s SS at the same tide of the same day; The action level has been
amended to ¡§23.5 and 120% of upstream control station¡¦s SS at the same tide of
the same day¡¨ since 25 March 2013. |
34.4 or 130% of SS at the
upstream control station at the same tide of same day and 10mg/L for Water
Services Department Seawater Intakes; The limit level has been
amended to ¡§34.4 and 130% of SS at the upstream control station at the same
tide of same day and 10mg/L for Water Services Department Seawater Intakes¡¨
since 25 March 2013 |
Notes:
(1) Depth-averaged
is calculated by taking the arithmetic means of reading of all three depths.
(2) For DO,
non-compliance of the water quality limit occurs when monitoring result is
lower that the limit.
(3) For SS &
turbidity non-compliance of the water quality limits occur when monitoring
result is higher than the limits.
(4) The change to
the Action and limit Levels for Water Quality Monitoring for the EM&A works
was approved by EPD on 25 March 2013.
Table 4.2 Water
Quality Monitoring Equipment
Equipment |
Brand and Model |
DO and Temperature Meter,
Salinity Meter, Turbidimeter and pH Meter |
N.A. (See Remark 1) |
Positioning Equipment |
N.A. (See Remark 1) |
Water Depth Detector |
N.A. (See Remark 1) |
Water Sampler |
N.A. (See Remark 1) |
Remark: 1. Not applicable. Water quality monitoring was temporarily suspended during
the reporting month. |
Table 4.3 Impact
Water Quality Monitoring Parameters and Frequency
Monitoring Stations |
Parameter, unit |
Frequency |
No. of depth |
Impact Stations: Control/Far Field
Stations: Sensitive Receiver
Stations: |
¡P
Depth, m ¡P
Temperature, oC ¡P
Salinity, ppt ¡P
Dissolved Oxygen
(DO), mg/L ¡P
DO Saturation, % ¡P
Turbidity, NTU ¡P
pH ¡P Suspended Solids (SS), mg/L |
Three times per week
during mid-ebb and mid-flood tides (within ¡Ó 1.75 hour of the predicted time) |
3 (1 m below water surface,
mid-depth and 1 m above sea bed, except where the
water depth is less than 6 m, in which case the mid-depth station may be
omitted. Should the water depth be less than 3 m, only the mid-depth station
will be monitored). |
Remark:
1) Original WQM stations IS8 and SR4(N) are located within the active work
area of TCNTE project and the access to the WQM stations IS8 (Coordinate:
E814251, N818412) and SR4(N) (Coordinate: E814705, N817859) are blocked by the
silt curtains of the Tung Chung New Town Extension (TCNTE) project. Alternative
monitoring stations IS8(N) (Coordinate: E814413, N818570) and SR4(N2)
(Coordinate: E814688, N817996) were proposed to replace the original monitoring
stations IS8 and SR4(N). Proposal for permanently relocating the aforementioned
stations was approved by EPD on 20 August 2019. The water quality monitoring
has been conducted at stations IS8(N) and SR4(N2) since 21 August 2019.
2) The water quality monitoring programme was temporarily suspended
during the reporting month since no marine works were scheduled or conducted,
therefore no water quality monitoring was conducted.
Table 4.4 Impact
Water Quality Monitoring Stations
Monitoring Stations |
Description |
Coordinates |
|
Easting |
Northing |
||
IS5 |
Impact Station (Close to
HKLR construction site) |
811579 |
817106 |
IS(Mf)6 |
Impact Station (Close to
HKLR construction site) |
812101 |
817873 |
IS7 |
Impact Station (Close to
HKBCF construction site) |
812244 |
818777 |
IS8(N) |
Impact Station (Close to
HKBCF construction site) |
814413 |
818570 |
IS(Mf)9 |
Impact Station (Close to
HKBCF construction site) |
813273 |
818850 |
IS10(N) |
Impact Station (Close to
HKBCF construction site) |
812942 |
820881 |
SR3(N) |
Sensitive receivers (San
Tau SSSI) |
810689 |
816591 |
SR4(N2) |
Sensitive receivers (Tai
Ho Inlet) |
814688 |
817996 |
SR5(N) |
Sensitive Receivers
(Artificial Reef in NE Airport) |
812569 |
821475 |
SR10A(N) |
Sensitive receivers (Ma
Wan Fish Culture Zone) |
823644 |
823484 |
SR10B(N2) |
Sensitive receivers (Ma
Wan Fish Culture Zone) |
823689 |
823159 |
CS2(A) |
Control Station (Mid-Ebb) |
805232 |
818606 |
CS(Mf)5 |
Control Station
(Mid-Flood) |
817990 |
821129 |
|
(a) The
in-situ water quality parameters including dissolved oxygen, temperature,
salinity and turbidity, pH were measured by
multi-parameter meters.
(a) Digital Differential Global Positioning Systems
(DGPS) were used to ensure that the correct location was selected prior to
sample collection.
(b) Portable, battery-operated echo sounders were used
for the determination of water depth at each designated monitoring station.
(c) All in-situ measurements were taken at 3 water
depths, 1 m below water surface, mid-depth and 1 m above sea
bed, except where the water depth was less than 6 m, in which case the
mid-depth station was omitted. Should the water depth be less than 3 m, only
the mid-depth station was monitored.
(d) At each measurement/sampling depth, two consecutive
in-situ monitoring (DO concentration and saturation, temperature, turbidity,
pH, salinity) and water sample for SS. The probes were retrieved out of the
water after the first measurement and then re-deployed for the second
measurement. Where the difference in the value between the first and second
readings of DO or turbidity parameters was more than 25% of the value of the
first reading, the reading was discarded and further
readings were taken.
(e) Duplicate samples from each independent sampling
event were collected for SS measurement. Water samples were collected using the
water samplers and the samples were stored in high-density polythene bottles.
Water samples collected were well-mixed in the water sampler prior to
pre-rinsing and transferring to sample bottles. Sample bottles were pre-rinsed
with the same water samples. The sample bottles were then be packed in
cool-boxes (cooled at 4oC without being frozen), and
delivered to ALS Technichem (HK) Pty Ltd. for the
analysis of suspended solids concentrations. The laboratory determination work
would be started within 24 hours after collection of the water samples. ALS Technichem (HK) Pty Ltd. is a HOKLAS accredited laboratory
and has comprehensive quality assurance and quality control programmes.
(f) The analysis method and detection limit for SS is
shown in Table 4.5.
Table 4.5 Laboratory
Analysis for Suspended Solids
Parameters |
Instrumentation |
Analytical
Method |
Detection
Limit |
Suspended Solid (SS) |
Weighting |
APHA 2540-D |
0.5mg/L |
(g) Other relevant data were recorded, including
monitoring location / position, time, water depth, tidal stages, weather
conditions and any special phenomena or work underway at the construction site
in the field log sheet for information.
Table 5.1 Action
and Limit Levels for Dolphin Monitoring
|
North Lantau Social Cluster |
|
NEL |
NWL |
|
Action
Level |
STG < 4.2 & ANI < 15.5 |
STG < 6.9 & ANI <
31.3 |
Limit Level |
(STG < 2.4 & ANI
< 8.9) and (STG < 3.9 & ANI < 17.9) |
Remarks:
1. STG means quarterly encounter rate of number of dolphin sightings.
2. ANI means quarterly encounter rate of total number of dolphins.
3. For North Lantau Social Cluster, AL will be trigger if either NEL or NWL fall below the criteria; LL will
be triggered if both NEL and NWL
fall below the criteria.
Table 5.2 Co-ordinates
of Transect Lines
Line No. |
Easting |
Northing |
|
Line No. |
Easting |
Northing |
||
1 |
Start Point |
804671 |
815456 |
|
13 |
Start Point |
816506 |
819480 |
1 |
End Point |
804671 |
831404 |
|
13 |
End Point |
816506 |
824859 |
2 |
Start Point |
805476 |
820800* |
|
14 |
Start Point |
817537 |
820220 |
2 |
End Point |
805476 |
826654 |
|
14 |
End Point |
817537 |
824613 |
3 |
Start Point |
806464 |
821150* |
|
15 |
Start Point |
818568 |
820735 |
3 |
End Point |
806464 |
822911 |
|
15 |
End Point |
818568 |
824433 |
4 |
Start Point |
807518 |
821500* |
|
16 |
Start Point |
819532 |
821420 |
4 |
End Point |
807518 |
829230 |
|
16 |
End Point |
819532 |
824209 |
5 |
Start Point |
808504 |
821850* |
|
17 |
Start Point |
820451 |
822125 |
5 |
End Point |
808504 |
828602 |
|
17 |
End Point |
820451 |
823671 |
6 |
Start Point |
809490 |
822150* |
|
18 |
Start Point |
821504 |
822371 |
6 |
End Point |
809490 |
825352 |
|
18 |
End Point |
821504 |
823761 |
7 |
Start Point |
810499 |
822000* |
|
19 |
Start Point |
822513 |
823268 |
7 |
End Point |
810499 |
824613 |
|
19 |
End Point |
822513 |
824321 |
8 |
Start Point |
811508 |
821123 |
|
20 |
Start Point |
823477 |
823402 |
8 |
End Point |
811508 |
824254 |
|
20 |
End Point |
823477 |
824613 |
9 |
Start Point |
812516 |
821303 |
|
21 |
Start Point |
805476 |
827081 |
9 |
End Point |
812516 |
824254 |
|
21 |
End Point |
805476 |
830562 |
10 |
Start Point |
813525 |
821176 |
|
22 |
Start Point |
806464 |
824033 |
10 |
End Point |
813525 |
824657 |
|
22 |
End Point |
806464 |
829598 |
11 |
Start Point |
814556 |
818853 |
|
23 |
Start Point |
814559 |
821739 |
11 |
End Point |
814556 |
820992 |
|
23 |
End Point |
814559 |
824768 |
12 |
Start Point |
815542 |
818807 |
|
24* |
Start Point |
805476* |
815900* |
12 |
End Point |
815542 |
824882 |
|
24* |
End Point |
805476* |
819100* |
Note:
Co-ordinates in red and marked with asterisk are revised co-ordinates of
transect line.
Methodology
6.1.1
To avoid
disturbance to the mudflat and nuisance to navigation, no fixed
marker/monitoring rod was installed at the monitoring stations. A high
precision Global Navigation Satellite System (GNSS) real time location fixing
system (or equivalent technology) was used to locate the station in the
precision of 1mm, which is reasonable under flat mudflat topography with uneven
mudflat surface only at micro level.
This method has been used on Agricultural Fisheries and Conservation
Department¡¦s (AFCD) project, namely Baseline Ecological Monitoring Programme
for the Mai Po Inner Deep Bay Ramsar Site for measurement of seabed levels.
6.1.2
Measurements
were taken directly on the mudflat surface. The Real Time Kinematic GNSS (RTK
GNSS) surveying technology was used to measure mudflat surface levels and 3D
coordinates of a survey point. The
RTK GNSS survey was calibrated against a reference station in the field before
and after each survey. The
reference station is a survey control point established by the Lands Department
of the HKSAR Government or traditional land surveying methods using
professional surveying instruments such as total station, level and/or geodetic
GNSS. The coordinates system was in
HK1980 GRID system. For this
contract, the reference control station was surveyed and established by
traditional land surveying methods using professional surveying instruments
such as total station, level and RTK GNSS.
The accuracy was down to mm level so that the reference control station
has relatively higher accuracy. As
the reference control station has higher accuracy, it was set as true
evaluation relative to the RTK GNSS measurement. All position and height correction were
adjusted and corrected to the reference control station. Reference station survey result and
professional land surveying calibration is shown as Table 6.1:
Table 6.1 Reference
Station Survey result and GNSS RTK calibration result of Round 1
Reference Station |
Easting (m) |
Northing (m) |
Baseline reference elevation (mPD) (A) |
Round 1 Survey (mPD) (B) |
Calibration Adjustment (B-A) |
T1 |
811248.660mE |
816393.173mN |
3.840 |
3.817 |
-0.023 |
T2 |
810806.297mE |
815691.822mN |
4.625 |
4.653 |
+0.028 |
T3 |
810778.098mE |
815689.918mN |
4.651 |
4.660 |
+0.009 |
T4 |
810274.783mE |
816689.068mN |
2.637 |
2.709 |
+0.072 |
6.1.3
The precision
of the measured mudflat surface level reading (vertical precision setting) was
within 10 mm (standard deviation) after averaging the valid survey records of
the XYZ HK1980 GRID coordinates.
Each survey record at each station was computed by averaging at least
three measurements that are within the above specified precision setting. Both
digital data logging and written records were collected in the field. Field
data on station fixing and mudflat surface measurement were recorded.
Monitoring Locations
6.1.4
Four
monitoring stations were established based on the site conditions for the
sedimentation monitoring and are shown in Figure 6.1.
Monitoring Results
6.1.5
The baseline
sedimentation rate monitoring was in September 2012 and impact sedimentation
rate monitoring was undertaken on 7 December 2020. The mudflat surface levels
at the four established monitoring stations and the corresponding XYZ HK1980
GRID coordinates are presented in Table
6.2 and Table 6.3.
Table 6.2 Measured
Mudflat Surface Level Results
Baseline Monitoring
(September 2012) |
Impact Monitoring
(December 2020) |
|||||
Monitoring
Station |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
S1 |
810291.160 |
816678.727 |
0.950 |
810291.159 |
816678.729 |
1.125 |
S2 |
810958.272 |
815831.531 |
0.864 |
810958.275 |
815831.532 |
0.958 |
S3 |
810716.585 |
815953.308 |
1.341 |
810716.576 |
815953.307 |
1.439 |
S4 |
811221.433 |
816151.381 |
0.931 |
811221.451 |
816151.379 |
1.092 |
Table 6.3 Comparison
of measurement
Comparison of measurement |
Remarks
and Recommendation |
|||
Monitoring Station |
Easting (m) |
Northing (m) |
Surface Level (mPD) |
|
S1 |
-0.001 |
0.002 |
0.175 |
Level continuously increased |
S2 |
0.003 |
0.001 |
0.094 |
Level continuously increased |
S3 |
-0.009 |
-0.001 |
0.098 |
Level continuously increased |
S4 |
0.018 |
-0.002 |
0.161 |
Level continuously increased |
6.1.6
This measurement result was generally and
relatively higher than the baseline measurement at S1, S2, S3 and S4. The
mudflat level is continuously increased.
6.2.1
The mudflat
monitoring covered water quality monitoring data. Reference was made to the
water quality monitoring data of the representative water quality monitoring
station (i.e. SR3(N)) as in the EM&A Manual. The water quality monitoring
location (SR3(N)) is shown in Figure 2.1.
6.2.2
Water quality monitoring in San Tau (monitoring
station SR3(N)) was conducted in December 2020 as part of mudflat monitoring.
The monitoring parameters included dissolved oxygen (DO), turbidity and
suspended solids (SS). The water
monitoring results for station SR3(N) were extracted and summarised below:
Table 6.4 Water
Quality Monitoring Results (Depth Average) at Station SR3(N)
Date |
Mid Ebb Tide |
Mid Flood Tide |
||||
DO (mg/L) |
Turbidity (NTU) |
SS (mg/L) |
DO (mg/L) |
Turbidity (NTU) |
SS (mg/L) |
|
01-Dec-2020 |
7.3 |
4.1 |
6.4 |
7.4 |
4.2 |
5.7 |
03-Dec-2020 |
7.4 |
3.4 |
6.6 |
7.6 |
3.3 |
5.9 |
05-Dec-2020 |
6.1 |
4.5 |
3.0 |
6.3 |
4.2 |
3.5 |
08-Dec-2020 |
7.6 |
3.3 |
6.4 |
7.4 |
3.3 |
6.3 |
10-Dec-2020 |
7.6 |
4.7 |
10.2 |
7.7 |
4.6 |
8.1 |
12-Dec-2020 |
6.7 |
3.3 |
2.4 |
6.8 |
3.3 |
3.1 |
15-Dec-2020 |
7.7 |
4.6 |
8.8 |
7.6 |
4.6 |
9.0 |
17-Dec-2020 |
7.7 |
4.6 |
11.8 |
7.6 |
4.6 |
16.2 |
19-Dec-2020 |
6.8 |
3.3 |
3.1 |
6.7 |
3.3 |
3.1 |
22-Dec-2020 |
8.1 |
6.3 |
7.9 |
7.9 |
6.6 |
9.0 |
24-Dec-2020 |
7.8 |
5.1 |
9.4 |
7.8 |
4.1 |
9.1 |
26-Dec-2020 |
7.3 |
3.2 |
2.5 |
6.8 |
2.6 |
2.5 |
29-Dec-2020 |
8.2 |
5.4 |
4.9 |
8.2 |
4.4 |
5.9 |
31-Dec-2020 |
7.4 |
7.4 |
12.3 |
7.4 |
7.5 |
9.4 |
Average |
7.4 |
4.5 |
6.8 |
7.4 |
4.3 |
6.9 |
|
Sampling Zone
6.3.1
In order to collect
baseline information of mudflats in the study site, the study site was divided
into three sampling zones (labeled as TC1, TC2, TC3) in Tung Chung Bay and one
zone in San Tau (labeled as ST) (Figure 2.1
of Appendix I). The horizontal shoreline of sampling zones
TC1, TC2, TC3 and ST were about 250 m, 300 m, 300 m and 250 m, respectively (Figure 2.2 of Appendix I). Survey of horseshoe crabs, seagrass beds and
intertidal communities were conducted in every sampling zone. The present
survey was conducted in December 2020 (totally 4 sampling days on 10th,
11th, 15th and 16th December 2020).
6.3.2 Since the field survey of June 2016, increasing number of trashes and
even big trashes (Figure 2.3 of Appendix I) were found in every sampling zone. It raised a concern about the solid
waste dumping and current-driven waste issues in Tung Chung Wan. Respective
measures (e.g. manual clean-up) should be implemented by responsible governmental
agency units.
Horseshoe Crabs
6.3.3
Active search method was adopted for horseshoe crab monitoring by two
experienced surveyors in every sampling zone. During the search period, any
accessible and potential area would be investigated for any horseshoe crab
individuals within 2-3 hour of low tide period (tidal level below 1.2 m above
Chart Datum (C.D.)). Once a horseshoe crab individual was found, the species
was identified referencing to Li (2008). The prosomal width, inhabiting
substratum and respective GPS coordinate were recorded. A photographic record
was taken for future investigation. Any grouping behavior of individuals, if
found, was recorded. The horseshoe crab surveys were conducted on 10th (for ST), 11th
(for TC1), 15th (for TC2) and 16th
(for TC3) December 2020, which were cool and cloudy days.
6.3.4 In June 2017, a big horseshoe crab was tangled by a trash gill net in ST
mudflat (Figure 2.3 of Appendix I). It was released to sea once after photo recording. The horseshoe crab
of such size should be inhabiting sub-tidal environment while it forages on
intertidal shore occasionally during high tide period. If it is tangled by the
trash net for few days, it may die due to starvation or overheat during low
tide period. These trash gill nets are definitely ¡¥fatal trap¡¦ for the
horseshoe crabs and other marine life. Manual clean-up should be implemented as
soon as possible by responsible governmental agency units.
Seagrass Beds
6.3.5 Active search method was adopted for seagrass
bed monitoring by two experienced surveyors in every sampling zone. During the
search period, any accessible and potential area would be investigated for any
seagrass beds within 2-3 hours of low tide period. Once seagrass bed was found,
the species, estimated area, estimated coverage percentage and respective GPS
coordinates were recorded. The seagrass beds surveys were conducted on 10th (for ST), 11th (for TC1), 15th (for TC2) and 16th
(for TC3) December
2020, which were cool and cloudy days.
Intertidal Soft Shore Communities
6.3.6 The intertidal soft shore community surveys
were conducted in low tide period on 10th
(for ST), 11th (for TC1), 15th (for TC2) and 16th
(for TC3) December 2020. In every sampling zone, three 100m horizontal
transect lines were laid at high tidal level (H: 2.0m above C.D.), mid tidal
level (M: 1.5m above C.D.) and low tidal level (L: 1.0m above C.D.). Along
every horizontal transect line; ten random quadrats (0.5 m x 0.5m) were placed.
6.3.7
Inside a quadrat, any
visible epifauna was collected and was in-situ identified to the lowest
practical taxonomical resolution. Whenever possible a hand core sample (10 cm
internal diameter ´ 20 cm depth) of sediments was collected in the quadrat. The core sample
was gently washed through a sieve of mesh size 2.0 mm in-situ. Any visible
infauna was collected and identified. Finally, the top 5 cm surface sediment
was dug for visible infauna in the quadrat regardless of hand core sample was
taken.
6.3.8
All collected fauna
were released after recording except some tiny individuals that were too small
to be identified on site. These tiny individuals were taken to laboratory for
identification under dissecting microscope.
6.3.9
The taxonomic classification was conducted in
accordance to the following references: Polychaetes: Fauchald (1977), Yang and Sun (1988); Arthropods: Dai and
Yang (1991), Dong (1991); Mollusks: Chan and Caley (2003), Qi (2004), AFCD
(2018).
Data Analysis
6.3.10 Data collected from direct counting and core
sampling was pooled in every quadrat for data analysis. Shannon-Weaver
Diversity Index (H¡¦) and Pielou¡¦s Species Evenness
(J) were calculated for every quadrat using the formulae below,
H¡¦= -£U ( Ni / N ) ln ( Ni / N ) (Shannon and Weaver, 1963)
J = H¡¦ / ln S, (Pielou, 1966)
where S is the total number
of species in the sample, N is the total number of individuals, and Ni is the
number of individuals of the ith species.
6.4.1
In the event
of the impact monitoring results indicating that the density or the
distribution pattern of intertidal fauna and seagrass is found to be
significant different to the baseline condition (taking into account natural
fluctuation in the occurrence and distribution pattern such as due to seasonal
change), appropriate actions should be taken and additional mitigation measures
should be implemented as necessary.
Data should then be re-assessed and the need for any further monitoring
should be established. The action plan, as given in Table 6.5 should be undertaken within a period of 1 month after a
significant difference has been determined.
Table 5.5 Event
and Action Plan for Mudflat Monitoring
Event |
ET Leader |
IEC |
SO |
Contractor |
Density or the distribution pattern of horseshoe
crab, seagrass or intertidal soft shore communities recorded in the
impact or post-construction monitoring are significantly lower than or
different from those recorded in the baseline monitoring. |
Review historical data to ensure differences are as a result of
natural variation or previously observed seasonal differences; Identify source(s) of impact; Inform the IEC, SO and Contractor; Check monitoring data; Discuss additional monitoring and any other measures, with the IEC and
Contractor. |
Discuss monitoring with the ET and the Contractor; Review proposals for additional monitoring and any other measures
submitted by the Contractor and advise the SO accordingly. |
Discuss with the IEC additional monitoring requirements and any other
measures proposed by the ET; Make agreement on the measures to be implemented. |
Inform the SO and in writing; Discuss with the ET and the IEC and propose measures to the IEC and
the ER; Implement the agreed measures. |
Notes:
ET ¡V Environmental Team
IEC ¡V Independent Environmental Checker
SO ¡V Supervising Officer
Horseshoe Crabs
6.5.1 In total of 3
and 7 individuals of Carcinoscorpius rotundicauda and Tachypleus tridentatus
were found in present survey. The recorded individuals were mainly distributed along the shoreline
in ST. All of them were observed on similar substratum (fine sand or soft mud,
slightly submerged). Photo records of the observed horseshoe crab are shown in Figure 3.1 of Appendix I and the present survey result regarding
horseshoe crab are presented in Table 3.1 of Appendix I. The complete survey records are presented
in Annex II of Appendix
I.
6.5.2 Carcinoscorpius rotundicauda, were only found
in ST (3 ind.) with average body size 46.45 mm (prosomal width ranged 36.31 mm
¡V 55.02 mm). The search records in ST was moderate (ST: 0.50
ind. hr-1. Person-1). No Carcinoscorpius rotundicauda was found in TC1, TC2 and TC3 in present
survey.
6.5.3
For Tachypleus
tridentatus, 7 individuals with average body size
41.13 mm (prosomal width ranged 28.34 ¡V 56.49 mm) were found in ST. The search
record in ST was moderate (1.17 ind. hr-1. Person-1). No Tachypleus tridentatus was
found in TC1, TC2 and TC3 in present survey.
6.5.4
In the survey of March 2015, there was one
important finding that a mating pair of Carcinoscorpius
rotundicauda was found in ST (prosomal width:
male 155.1mm, female 138.2mm). It indicated the importance of ST as a breeding
ground of horseshoe crab. In June 2017, mating pairs of Carcinoscorpius
rotundicauda were found in TC2 (male 175.27 mm,
female 143.51 mm) and TC3 (male 182.08 mm, female 145.63 mm) (Figure 3.2 of Appendix I). In December 2017 and June 2018, one mating pair
was of Carcinoscorpius rotundicauda
was found in TC3 (December 2017: male 127.80 mm, female 144.61 mm; June 2018:
male 139 mm, female 149 mm). In June 2019, 2 mating pairs
of Tachypleus tridentatus with
large body sizes (male 150mm and Female 200mm; Male 180mm and Female 220mm) was
found in TC3. Another mating pair of Tachypleus tridentatus was found in ST (male 140mm and Female
180mm). In March 2020, a pair of Tachypleus tridentatus with large body sizes (male 123mm and
Female 137mm was recorded in TC1. Figure
3.2 of Appendix I shows the photographic records of
mating pairs found. The recorded mating pairs were found
nearly burrowing in soft mud at low tidal level (0.5-1.0 m above C.D.). The
smaller male was holding the opisthosoma (abdomen carapace) of larger female
from behind. A mating pair was found in TC1 in March 2020, it indicated that
breeding of horseshoe crab could be possible along the coast of Tung Chung Wan
rather than ST only, as long as suitable substratum
was available. Based on the frequency of encounter, the shoreline between TC3
and ST should be more suitable mating ground. Moreover
suitable breeding period was believed in wet season (March ¡V September) because
tiny individuals (i.e. newly hatched) were usually recorded in June and September
every year (Figure 3.3 of Appendix I). No mating pair
was found in December 2020 (present survey).
6.5.5
No large individuals (prosomal
width >100mm) of Carcinoscorpius rotundicauda and Tachypleus tridentatus was
recorded in December 2020 (present survey). In December 2018, one large individual of Carcinoscorpius rotundicauda
was found in TC3 (prosomal width 148.9 mm). In March 2019, 3 large individuals
(prosomal width ranged 220 ¡V 310mm) of Carcinoscorpius
rotundicauda were observed in TC2. In June 2019,
there were 3 and 7 large individuals of Tachypleus
tridentatus were recorded in ST (prosomal width
ranged 140 ¡V 180mm) and TC3 (prosomal width ranged 150 ¡V 220mm), respectively. In March 2020,
a mating pair of Tachypleus tridentatus was
recorded in TC1 with prosomal width 123 mm and 137mm. Based on their sizes, it indicated that
individuals of prosomal width larger than 100 mm would progress its nursery
stage from intertidal habitat to sub-tidal habitat of Tung Chung Wan. The photo
records of the large horseshoe crab are shown in Figure 3.4 of Appendix I. These large individuals might move onto
intertidal shore occasionally during high tide for foraging and breeding.
Because they should be inhabiting sub-tidal habitat most of the time. Their
records were excluded from the data analysis to avoid mixing up with juvenile
population living on intertidal habitat.
6.5.6
No marked individual of horseshoe crab was recorded in December
2020 (present survey). Some marked individuals were found in the previous
surveys of September 2013, March 2014 and September 2014. All of them were
released through a conservation programme in charged
by Prof. Paul Shin (Department of Biology and Chemistry, The City University of
Hong Kong (CityU)). It was a re-introduction trial of
artificial bred horseshoe crab juvenile at selected sites. So that the
horseshoe crabs population might be restored in the
natural habitat. Through a personal conversation with Prof. Shin, about 100
individuals were released in the sampling zone ST on 20 June 2013. All of them
were marked with color tape and internal chip detected by specific chip sensor.
There should be second round of release between June and September 2014 since
new marked individuals were found in the survey of September 2014.
6.5.7 The artificial bred individuals, if found,
would be excluded from the results of present monitoring programme
in order to reflect the changes of natural population. However, the mark on
their prosoma might have been detached during moulting
after a certain period of release. The artificially released individuals were
no longer distinguishable from the natural population without the specific chip
sensor. The survey data collected would possibly cover both natural population
and artificially bred individuals.
Population
difference among the sampling zones
6.5.8
Figure 3.5 and 3.6 of Appendix I show the changes of number of individuals, mean prosomal width and
search record of horseshoe crabs Carcinoscorpius rotundicauda and Tachypleus tridentatus in respectively in each sampling zone
throughout the monitoring period.
6.5.9
To consider the entire monitoring
period for TC3 and ST, medium to high search records (i.e. number of
individuals) of both species (Carcinoscorpius rotundicauda and Tachypleus tridentatus) were usually found in wet
season (June and September). The search record of ST was higher from September
2012 to June 2014 while it was replaced by TC3 from September 2014 to June
2015. The search records were similar between two sampling zones from September
2015 to June 2016. In September 2016, the search record of Carcinoscorpius rotundicauda
in ST was much higher than TC3. From March to June 2017, the search records of
both species were similar again between two sampling zones. It showed a natural
variation of horseshoe crab population in these two zones due to weather
condition and tidal effect. No obvious difference of horseshoe crab population
was noted between TC3 and ST. In September 2017, the search records of both
horseshoe crab species decreased except the Carcinoscorpius rotundicauda
in TC3. The survey results were different from previous findings that there
were usually higher search records in September. One possible reason was that
the serial cyclone hit decreased horseshoe crab activity (totally 4 cyclone
records between June and September 2017, to be discussed in 'Seagrass survey'
section). From December 2017 to September 2018, the search records of both
species increased again to low-moderate level in ST. From December 2018 to
March 2020, the search records of Carcinoscorpius rotundicauda change from
very low to low while the change of Tachypleus tridentatus was similar during this period. From June 2020
to September 2020, the search records of both species, Carcinoscorpius rotundicauda and
Tachypleus tridentatus,
were increased to moderate level in ST. However, none of them were recorded
in TC3. Relatively higher population fluctuation of Carcinoscorpius rotundicauda
was observed in TC3. In December 2020 (present
survey), the search records of both species, Carcinoscorpius
rotundicauda and Tachypleus
tridentatus, were decreased to low level in ST.
None of them were recorded in TC3 from June 2020 to December 2020. It is similar to the previous findings of December. It may due to
the weather variation of dry season.
6.5.10
For TC1, the search record was at
low to moderate level throughout the monitoring period. The change of Carcinoscorpius rotundicauda
was relatively more variable than that of Tachypleus tridentatus. Relatively, the search
record was very low in TC2. There were occasional records of 1 to 4 individuals
between March and September throughout the monitoring period. The maximum
record was 6 individuals only in June 2016.
Seasonal variation of horseshoe crab population
6.5.13
Throughout
the monitoring period, the search records of horseshoe crabs were fluctuated
and at moderate ¡V very low level in June (Figures
3.5 and 3.6 of Appendix
I). Low ¡V Very low search record was found in June 2013, totally 82
individuals of Tachypleus tridentatus
and 0 ind. of Carcinoscorpius rotundicauda were
found in TC1, TC3 and ST. Compare with the search record of June 2013, the
numbers of Tachypleus tridentatus
were gradually decreased in June 2014 and 2015 (55 ind. in 2014 and 18 ind. in
2015); the number of Carcinoscorpius
rotundicauda raise to 88 and 66 individuals. in
June 2014 and 2015 respectively. In June 2016, the search record increased
about 3 times compare with June 2015. In total, 182 individuals of Carcinoscorpius rotundicauda
and 47 individuals. of Tachypleus tridentatus
were noted, respectively. Then, the search record was similar
to June 2016. The number of recorded Carcinoscorpius rotundicauda (133
ind.) slightly dropped in June 2017. However, that of Tachypleus tridentatus rapidly increased (125
ind.). In June 2018, the search record was low to moderate while the numbers of
Tachypleus tridentatus
dropped sharply (39 ind.). In June 2019, 10 individuals of Tachypleus tridentatus were
observed in TC3 and ST. All of them, however, were large
individuals (prosomal width >100mm), their records are excluded from the
data analysis to avoid mixing up with the juvenile population living on
intertidal habitat. Until September 2020, the number of Carcinoscorpius
rotundicauda and Tachypleus
tridentatus gradually increased to 39 ind. and 28
ind., respectively. Throughout the monitoring period, similar distribution of
horseshoe crabs population were found in September.
Most of the horseshoe crabs were found in TC3 and ST.
6.5.14
In
December 2020 (present survey), the number of Carcinoscorpius
rotundicauda and Tachypleus
tridentatus greatly decreased to 3 ind. and 7
ind., respectively. Throughout the monitoring period, similar distribution of
horseshoe crabs population were found in December. All
the horseshoe crabs were found in ST.
6.5.15
The search record of horseshoe crab declined
obviously in all sampling zones during dry season especially December (Figures
3.5 and 3.6 of Appendix
I) throughout the monitoring period. Very low
¡V low search record was found in December from 2012 to 2015 (0-4 ind. of Carcinoscorpius rotundicauda
and 0-12 ind. of Tachypleus tridentatus). The horseshoe crabs were inactive and
burrowed in the sediments during cold weather (<15 ºC). Similar results of
low search record in dry season were reported in a previous territory-wide
survey of horseshoe crab. For example, the search records in Tung Chung Wan
were 0.17 ind. hr-1person-1 and 0.00 ind. hr-1
person-1 in wet season and dry season respectively (details see Li,
2008). Compare with the search record of December from 2012 to 2015, which of
December 2016 were much higher relatively. There were totally 70 individuals of
Carcinoscorpius rotundicauda
and 24 individuals of Tachypleus tridentatus in TC3 and ST. Since the survey was carried
in earlier December with warm and sunny weather (~22 ºC during dawn according
to Hong Kong Observatory database, Chek Lap Kok station on 5 December 2016), the horseshoe crab was
more active (i.e. move onto intertidal shore during high tide for foraging and
breeding) and easier to be found. In contrast, there was no search record in
TC1 and TC2 because the survey was conducted in mid-December with colder and
cloudy weather (~20 ºC during dawn on 19 December). The horseshoe
crab activity would decrease gradually with the colder climate. In December of 2017, 2018 and 2019, very low search records
were found again as mentioned above.
6.5.16
From
September 2012 to December 2013, Carcinoscorpius rotundicauda was less common
species relative to Tachypleus tridentatus.
Only 4 individuals were ever recorded in ST in December 2012. This species had
ever been believed of very low density in ST hence the encounter rate was very
low. In March 2014, it was found in all sampling zones with higher abundance in
ST. Based on its average size (mean prosomal width 39.28 mm - 49.81 mm), it
indicated that breeding and spawning of this species had occurred about 3 years
ago along the coastline of Tung Chung Wan. However, these individuals were
still small while their walking trails were inconspicuous. Hence there was no
search record in previous sampling months. Since March 2014, more individuals
were recorded due to larger size and higher activity (i.e. more conspicuous
walking trail).
6.5.17
For Tachypleus tridentatus,
sharp increase of number of individuals was recorded in ST during the wet
season of 2013 (from March to September). According to a personal conversation
with Prof. Shin (CityU), his monitoring team had
recorded similar increase of horseshoe crab population during wet season. It
was believed that the suitable ambient temperature increased its
conspicuousness. However similar pattern was not recorded in the following wet
seasons. The number of individuals increased in March and June 2014 and
followed by a rapid decline in September 2014. Then the number of individuals
fluctuated slightly in TC3 and ST until March 2017. Apart from natural
mortality, migration from nursery soft shore to subtidal habitat was another
possible cause. Since the mean prosomal width of Tachypleus tridentatus continued to grow and
reached about 50 mm since March 2014. Then it varied slightly between 35 - 65
mm from September 2014 to March 2017. Most of the individuals might have
reached a suitable size (e.g. prosomal width 50 - 60 mm) strong enough to
forage in sub-tidal habitat. In June 2017, the number of individuals increased
sharply again in TC3 and ST. Although mating pair of Tachypleus tridentatus was not found in previous
surveys, there should be new round of spawning in the wet season of 2016. The
individuals might have grown to a more conspicuous size in 2017 accounting for
higher search record. In September 2017, moderate numbers of individual were
found in TC3 and ST indicating a stable population size. From September 2018 to
March 2020, the population size was low while natural mortality was the
possible cause. From June 2020 to September 2020, the population
size of Tachypleus tridentatus
increased to moderate level in ST while the mean proposal width of them
continued to grow and reach about 55mm.
It indicated
that a stable growth of juveniles after the spawning season. In December
2020 (present survey), the population size of Tachypleus
tridentatus decreased to low level in ST and the
mean proposal width of them decreased to about 41mm. It may due to the natural
mortality.
6.5.18
Recently,
Carcinoscorpius rotundicauda
was a more common horseshoe crab species in Tung Chung Wan. It was recorded in
the four sampling zones while the majority of
population located in TC3 and ST. Due to potential breeding last year, the
number of Tachypleus tridentatus
became increased ST. Since TC3 and ST were regarded as important nursery
ground for both horseshoe crab species, box plots of prosomal width of two
horseshoe crab species were constructed to investigate the changes of
population in details.
Box plot of
horseshoe crab populations in TC3
6.5.19 Figure 3.7 of Appendix I shows the changes of prosomal width of Carcinoscorpius rotundicauda
and Tachypleus tridentatus
in TC3. As mentioned above, Carcinoscorpius
rotundicauda was rarely found between September
2012 and December 2013 hence the data were lacking. In March 2014, the major
size (50% of individual records between upper (top box) and lower quartile
(bottom box)) ranged 40 ¡V 60 mm while only few individuals were found.
From March 2014 to September 2018, the median prosomal width (middle line of
whole box) and major size (whole box) decreased after March of every year. It
was due to more small individuals found in June indicating new rounds of
spawning. Also, there were slight increasing trends of body size from June to
March of next year since 2015. It indicated a stable growth of individuals.
Focused on larger juveniles (upper whisker), the size range was quite variable
(prosomal width 60 ¡V 90 mm) along the sampling months.
Juveniles reaching this size might gradually migrate to sub-tidal habitats.
6.5.20
For Tachypleus tridentatus, the major size ranged 20-50 mm while the
number of individuals fluctuated from September 2012 to June 2014. Then a
slight but consistent growing trend was observed from September 2014 to June
2015. The prosomal width increased from 25 ¡V 35 mm to 35 ¡V 65 mm. As mentioned, the large individuals
might have reached a suitable size for migrating from the nursery soft shore to
subtidal habitat. It accounted for the declined population in TC3. From March
to September 2016, slight increasing trend of major size was noticed again.
From December 2016 to June 2017, similar increasing trend of major size was
noted with much higher number of individuals. It reflected new round of
spawning. In September 2017, the major size decreased while the trend was
different from previous two years. Such decline might be the cause of serial
cyclone hit between June and September 2017 (to be discussed in the 'Seagrass
survey' section). From December 2017 to September 2018, increasing trend was
noted again. It
indicated a stable growth of individuals. From September 2018 to that of next
year, the average prosomal widths were decreased from 60mm to 36mm. It
indicated new rounds of spawning occurred during September to November 2018. In
December 2019, an individual with larger body size (prosomal width 65mm) was
found in TC3 which reflected the stable growth of individuals. In March 2020,
the average prosomal width (middle line of the whole box) of Tachypleus tridentatus in
TC3 was 33.97 mm which is smaller than that in December 2019. It was in normal
fluctuation. From June 2020 to December 2020 (present survey), no horseshoe
crab was recorded in TC3. Across the whole monitoring period, the larger
juveniles (upper whisker) usually reached 60 ¡V 80 mm in prosomal width, even
90 mm occasionally. The juveniles reaching this size might gradually migrate to
sub-tidal habitats.
Box plot of horseshoe crab populations in ST
6.5.21 Figure 3.8 of Appendix I shows the changes of prosomal width of Carcinoscorpius rotundicauda
and Tachypleus tridentatus
in ST. As mentioned above, Carcinoscorpius rotundicauda was rarely found between September 2012
and December 2013 hence the data were lacking. From March 2014 to September
2018, the size of major population decreased and more small individuals (i.e.
lower whisker) were recorded after June of every year. It indicated new round
of spawning. Also, there were similar increasing trends of body size from September
to June of next year between 2014 and 2017. It indicated a stable growth of
individuals. The larger juveniles (i.e. upper whisker usually ranged 60 ¡V 80 mm in prosomal width except
one individual (prosomal width 107.04 mm) found in March 2017. It reflected
juveniles reaching this size would gradually migrate to sub-tidal habitats.
6.5.22 For Tachypleus tridentatus,
a consistent growing trend was observed for the major population from December
2012 to December 2014 regardless of change of search record. The prosomal width
increased from 15-30 mm to 60 ¡V 70 mm. As
mentioned, the large juveniles might have reached a suitable size for migrating
from the nursery soft shore to subtidal habitat. From March to September 2015,
the size of major population decreased slightly to a prosomal width 40 ¡V 60 mm. At the
same time, the number of individuals decreased gradually. It further indicated
some of large juveniles might have migrated to sub-tidal habitat, leaving the
smaller individuals on shore. There was an overall growth trend. In December
2015, two big individuals (prosomal width 89.27 mm and 98.89 mm) were recorded
only while it could not represent the major population. In March 2016, the
number of individual was very few in ST that no box
plot could be produced. In June 2016, the prosomal width of major population
ranged 50 ¡V 70 mm. But it
dropped clearly to 30 ¡V 40 mm in
September 2016 followed by an increase to 40 ¡V 50 mm in
December 2016, 40 ¡V 70 mm in March
2017 and 50 ¡V 60mm in June
2017. Based on overall higher number of small individuals from June 2016 to
September 2017, it indicated another round of spawning. From September 2017 to
June 2018, the major size range increased slightly from 40 ¡V 50 mm to 45 ¡V 60 mm
indicating a continuous growth. In September 2018, decrease of major size was
noted again that might reflect new round of spawning. Throughout the monitoring
period, the larger juveniles ranged 60 ¡V 80 mm in
prosomal width. Juveniles reaching this size would gradually migrate to
sub-tidal habitats.
6.5.23
As a summary for horseshoe crab
populations in TC3 and ST, there were spawning of Carcinoscorpius rotundicauda
from 2014 to 2018 while the spawning time should be in spring. The population
size was consistent in these two sampling zones. For Tachypleus tridentatus, small individuals were
rarely found in both zones from 2014 to 2015. It was believed no occurrence of
successful spawning. The existing individuals (that recorded since 2012) grew
to a mature size and migrated to sub-tidal habitat. Hence the number of
individuals decreased gradually. From 2016 to 2018, new rounds of spawning were
recorded in ST while the population size increased to a moderate level.
6.5.24
In
March 2019 to June 2019, no horseshoe crab juveniles (prosomal width <100mm) were recorded in TC3 and ST. All recorded horseshoe crabs were large
individuals (prosomal width >100mm) or mating pairs which were all excluded
from the data analysis. From September
2019 to September 2020, the population size of both horseshoe crab species in
ST gradually increased to moderate
level while their body sizes were mostly in small to medium range (~23 ¡V 55mm). It
indicated the natural stable growth of the horseshoe crab juveniles. In December 2020 (present survey), the population size of both horseshoe
crab species in ST dropped to low level while their body sizes were mostly in
small to medium range (~28 ¡V 56mm). It showed the natural mortality and
seasonal variation of horseshoe crab.
Impact of the HKLR project
6.5.25 It was the 33rd survey of the EM&A programme
during construction period. Based on the monitoring results, no detectable
impact on horseshoe crab was revealed due to HKLR project. The population
change was mainly determined by seasonal variation, no abnormal phenomenon of
horseshoe crab individual, such as large number of dead individuals on the
shore) had been reported.
Seagrass Beds
6.5.26
Only seagrass species Halophila
ovalis was
found in present survey, which was found in TC3 and ST. In ST, there were two small sized and one large sized of seagrass beds found at tidal zone 1.5 m above C.D nearby
mangroves plantation. The larger
strand had area ~900 m2 in high vegetation coverage (90 ¡V 100%). At
close vicinity, two small sized (~4 and 50 m2) of Halophila ovalis
beds were observed
at tidal zone 1.5 above C.D. The ~4m2
of Halophila ovalis beds
were in moderate to high vegetation coverage (70-80%) while the ~50m2
and ~900m2 of Halophila ovalis beds were in high vegetation coverage
(90 ¡V 100%) respectively . In TC3, three small patches of Halophila ovalis were found at
tidal zone 1.5 ¡V 2.0m above
C.D. These seagrass patch had area 30m2 ¡V 54m2.
They were in moderate to high vegetation coverage (50 ¡V 100%). Another seagrass species Zostera japonica was not
found in present survey. Table 3.2 of Appendix
I summarizes the results of present seagrass beds survey and the
photograph records of the seagrass are shown on Figure 3.9 of Appendix I. The complete record throughout the monitoring period is presented in Annex III of Appendix
I.
6.5.27
Since the commencement of the
EM&A monitoring programme, two species of
seagrass Halophila ovalis and Zostera japonica were recorded in TC3 and ST (Figure 3.10 of Appendix I). In general, Halophila ovalis was
occasionally found in TC3 in few, small to medium patches. But it was commonly
found in ST in medium to large seagrass bed. Moreover
it had sometimes grown extensively and had covered significant mudflat area at 0.5 ¡V 2.0 m
above C.D. between TC3
and ST. Another seagrass species Zostera japonica was found in ST only. It was relatively
lower in vegetation area and co-existed with Halophila ovalis nearby the
mangrove strand at 2.0 m above C.D.
6.5.28
According to
the previous results, majority of seagrass bed was confined in ST, the temporal
change of both seagrass species were investigated in
details:
Temporal variation of seagrass beds
6.5.29
Figure
3.11 of Appendix I shows the changes of estimated total area of
seagrass beds in ST along the sampling months. For Zostera japonica, it was not recorded in the 1st
and 2nd surveys of monitoring programme.
Seasonal recruitment of few, small patches (total seagrass area: 10 m2)
was found in Mach 2013 that grew within the large patch of seagrass Halophila
ovalis. Then, the patch size increased and merged gradually with the warmer
climate from March to June 2013 (15 m2). However, the patch size
decreased and remained similar from September 2013 (4 m2) to March
2014 (3 m2). In June 2014, the patch size increased obviously again
(41 m2) with warmer climate followed by a decrease between September
2014 (2 m2) and December 2014 (5 m2). From March to June
2015, the patch size increased sharply again (90 m2). It might be
due to the disappearance of the originally dominant seagrass Halophila
ovalis resulting in less competition for substratum and nutrients. From
September 2015 to June 2016, it was found coexisting with seagrass Halophila
ovalis with steady increasing patch size (from 44 m2 to 115 m2)
and variable coverage. In September 2016, the patch size decreased again to (38
m2) followed by an increase to a horizontal strand (105.4 m2)
in June 2017. And it did no longer co-exist with Halophila ovalis.
Between September 2014 and June 2017, an increasing trend was noticed from
September to June of next year followed by a rapid decline in September of next
year. It was possibly the causes of heat stress, typhoon and stronger grazing
pressure during wet season. However, such increasing trend was not found from
September 2017 to December 2020 (present survey) while no patch of Zostera japonica was found.
6.5.30
For Halophila ovalis, it was recorded
as 3 ¡V 4 medium to large patches (area 18.9 - 251.7
m2; vegetation coverage 50 - 80%)
beside the mangrove vegetation at tidal level 2 m above C.D. in September 2012.
The total seagrass bed area grew steadily from 332.3 m2 in September
2012 to 727.4 m2 in December 2013. Flowers were observed in the
largest patch during its flowering period. In March 2014, 31 small
to medium patches were newly recorded (variable area 1 ¡V 72 m2 per patch, vegetation coverage 40-80% per patch) in
lower tidal zone between 1.0 and 1.5 m above C.D. The total seagrass area
increased further to 1350 m2. In June 2014, these small and medium
patches grew and extended to each other. These patches were no longer
distinguishable and were covering a significant mudflat area of ST. It was
generally grouped into 4 large patches (1116 - 2443 m2) of seagrass
beds characterized of patchy distribution, variable vegetable coverage (40 -
80%) and smaller leaves. The total seagrass bed area increased sharply to 7629
m2. In September 2014, the total seagrass area declined sharply to
1111m2. There were only 3 - 4 small to large patches (6 - 253 m2)
at high tidal level and 1 large patch at low tidal level (786 m2). Typhoon
or strong water current was a possible cause (Fong, 1998). In September 2014,
there were two tropical cyclone records in Hong Kong (7th-8th September:
no cyclone name, maximum signal number 1; 14th - 17th September:
Kalmaegi, maximum signal number 8SE) before the
seagrass survey dated 21st September 2014. The strong water current
caused by the cyclone, Kalmaegi especially, might
have given damage to the seagrass beds. In addition, natural heat stress and
grazing force were other possible causes reducing seagrass beds area. Besides,
very small patches of Halophila ovalis could be found in other mud flat
area in addition to the recorded patches. But it was hardly distinguished due
to very low coverage (10 - 20%) and small leaves.
6.5.31
In
December 2014, all the seagrass patches of Halophila
ovalis disappeared in ST. Figure
3.12 of Appendix I shows the difference of the original seagrass beds area nearby the
mangrove vegetation at high tidal level between June 2014 and December
2014.Such rapid loss would not be seasonal phenomenon because the seagrass beds
at higher tidal level (2.0 m above C.D.) were present and normal in December
2012 and 2013. According to Fong (1998), similar incident had occurred in ST in
the past. The original seagrass area had declined significantly during the
commencement of the construction and reclamation works for the international
airport at Chek Lap Kok in
1992. The seagrass almost disappeared in 1995 and recovered gradually after the
completion of reclamation works. Moreover, incident of rapid loss of seagrass
area was also recorded in another intertidal mudflat in Lai Chi Wo in 1998 with
unknown reason. Hence, Halophila ovalis
was regarded as a short-lived and r-strategy seagrass that could colonize areas
in short period but disappears quickly under unfavourable
conditions (Fong, 1998).
Unfavourable conditions to seagrass Halophila ovalis
6.5.32
Typhoon or strong water current was suggested as one unfavorable
condition to Halophila ovalis (Fong,
1998). As mentioned above, there were two tropical cyclone records in Hong Kong
in September 2014. The strong water current caused by the cyclones might have
given damage to the seagrass beds.
6.5.33
Prolonged light deprivation due to turbid water
would be another unfavorable condition. Previous studies reported that Halophila
ovalis had little tolerance to light deprivation. During experimental
darkness, seagrass biomass declined rapidly after 3 - 6 days and seagrass died
completely after 30 days. The rapid death might be due to shortage of available
carbohydrate under limited photosynthesis or accumulation of phytotoxic end
products of anaerobic respiration (details see Longstaff et al., 1999).
Hence the seagrass bed of this species was susceptible to temporary light
deprivation events such as flooding river runoff (Longstaff and Dennison,
1999).
6.5.34
In
order to investigate any deterioration of water quality (e.g. more turbid) in
ST, the water quality measurement results at two closest monitoring stations
SR3 and IS5 of the EM&A programme were obtained
from the water quality monitoring team. Based on the results from June to
December 2014, the overall water quality was in normal fluctuation except there
was one exceedance of suspended solids (SS) at both stations in September. On
10th September 2014, the SS concentrations measured during mid-ebb
tide at stations SR3 (27.5 mg/L) and IS5 (34.5 mg/L) exceeded the Action Level
(≤23.5 mg/L and 120% of upstream control station¡¦s reading) and Limit Level (≤34.4 mg/L and 130% of upstream control station¡¦s reading) respectively. The turbidity readings at SR3 and IS5 reached
24.8-25.3 NTU and 22.3-22.5 NTU respectively. The temporary turbid water should
not be caused by the runoff from upstream rivers. Because there was no rain or
slight rain from 1st to 10th September 2014 (daily total
rainfall at the Hong Kong International Airport: 0-2.1 mm; extracted from the
climatological data of Hong Kong Observatory). The effect of upstream runoff on
water quality should be neglectable in that period. Moreover, the exceedance of
water quality was considered unlikely to be related to the contract works of
HKLR according to the ¡¥Notifications of Environmental Quality Limits Exceedances¡¦
provided by the respective environmental team. The respective construction of
seawall and stone column works, which possibly caused turbid water, was carried
out within silt curtain as recommended in the EIA report. Moreover, there was
no leakage of turbid water, abnormity or malpractice recorded during water
sampling. In general, the exceedance of suspended solids concentration was considered to be attributed to other external factors,
rather than the contract works.
6.5.35
Based
on the weather condition and water quality results in ST, the co-occurrence of
cyclone hit and turbid waters in September 2014 might have combined the adverse
effects on Halophila ovalis that
leaded to disappearance of this short-lived and r-strategy seagrass species.
Fortunately, Halophila ovalis was a
fast-growing species (Vermaat et al., 1995). Previous studies showed that the seagrass bed could
be recovered to the original sizes in 2 months through vegetative propagation
after experimental clearance (Supanwanid, 1996).
Moreover it was reported to recover rapidly in less than 20 days after dugong
herbivory (Nakaoka and Aioi,
1999).As mentioned, the disappeared seagrass in ST in 1995 could recover
gradually after the completion of reclamation works for international airport
(Fong, 1998).The seagrass beds of Halophila
ovalis might recolonize in the mudflat of ST through seed reproduction as
long as there was no unfavourable condition in the
coming months.
Recolonization of seagrass beds
6.5.36 Figure 3.12 of Appendix I shows the
recolonization of seagrass bed in ST from December 2014 to June 2017. From
March to June 2015, 2 - 3 small patches of Halophila
ovalis were newly found co-inhabiting with another seagrass species Zostera japonica. But the total patch area of Halophila ovalis was still very low
compare with previous records. The recolonization rate was low while cold
weather and insufficient sunlight were possible factors between December 2014
and March 2015. Moreover, it would need to compete with seagrass Zostera japonica for substratum and nutrient,
because Zostera japonica had extended and covered the
original seagrass bed of Halophila ovalis
at certain degree. From June 2015 to March 2016, the total seagrass area of Halophila ovalis had increased rapidly
from 6.8 m2 to 230.63 m2. It had recolonized its original
patch locations and covered its competitor Zostera japonica. In June 2016, the total seagrass area increased sharply
to 4707.3m2. Similar to the previous
records of March to June 2014, the original patch area of Halophila ovalis increased further to a horizontally long strand.
Another large seagrass beds colonized the lower tidal
zone (1.0 - 1.5 m above C.D.). In September 2016, this patch extended much and
covered significant soft mud area of ST, resulting in sharp increase of total
area (24245 m2). It indicated the second extensive colonization of
this r-selected seagrass. In December 2016, this extensive seagrass patch
decreased in size and had separated into few, undistinguishable patches.
Moreover, the horizontal strand nearby the mangrove vegetation decreased in
size. The total seagrass bed decreased to 12550 m2. From March to
June 2017, the seagrass bed area remained generally stable (12438 - 17046.5 m2)
but the vegetation coverage fluctuated (20 - 50% in March 2017 to 80-100% in
June 2017). The whole recolonization process took about 2.5 years.
Second disappearance of seagrass bed
6.5.37 In September
2017, the whole seagrass bed of Halophila
ovalis disappeared again along the shore of TC3 and ST (Figure 3.12 of Appendix I). Similar to the first disappearance of seagrass bed occurred
between September and December 2014, strong water current (e.g. cyclone) or
deteriorated water qualities (e.g. high turbidity) was the possible cause.
6.5.38 Between the
survey periods of June and September 2017, there were four tropical cyclone
records in Hong Kong (Merbok in 12 - 13th,
June; Roke in 23rd, Jul.; Hato in 22 - 23rd, Aug.; Pakhar
in 26-27th, Aug.) (Online database of Hong Kong Observatory). All of
them reaches signal 8 or above, especially Hato with
highest signal 10.
6.5.39 According to
the water quality monitoring results (July to August 2017) of the two closest
monitoring stations SR3 and IS5 of the respective EM&A programme,
the overall water quality was in normal fluctuation. There was an exceedance of
suspended solids (SS) at SR3 on 12 July 2017. The SS concentration reached 24.7
mg/L during mid-ebb tide, which exceeded the Action Level (≤ 23.5 mg/L).
But it was far below the Limit Level (≤ 34.4 mg/L).
Since such exceedance was slight and temporary, its effect to seagrass bed
should be minimal.
6.5.40 Overall, the
disappearance of seagrass beds in ST has believed the cause of serial cyclone
hit in July and August 2017. Based on previous findings, the seagrass beds of
both species were expected to recolonize in the mudflat as
long as the vicinal water quality was normal. The whole recolonization
process (from few, small patches to extensive strand) would be gradually
lasting at least 2 years. From December 2017 to March 2018, there was still no
recolonization of few, small patches of seagrass at the usual location (Figure 3.12 of Appendix I). It was
different from the previous round (March 2015 - June 2017). Until June 2018,
the new seagrass patches with small-medium size were found at the usual
location (seaward side of mangrove plantation at 2.0 m C.D.) again, indicating
the recolonization. However, the seagrass bed area decreased sharply to 22.5 m2
in September 2018. Again, it was believed that the decrease was due to the hit
of the super cyclone in September 2018 (Mangkhuton 16th
September, highest signal 10). From December 2018 to June 2019, the seagrass
bed area increased from 404 m2 to 1229 m2 while the vegetation
coverage is also increased. (December 2018: 5 ¡V 85%; March 2019: 50 ¡V 100% and
June 2019: 60 ¡V 100%). Relatively, the whole recolonization process would occur
slower than the previous round (more than 2 years). From September 2019 to December2020
(present survey), the seagrass bed area slightly decreased from 1200 m2 to
954 m2 which were in normal fluctuation.
Impact
of the HKLR project
6.5.41 It was the 33rd
survey of the EM&A programme during construction
period. Throughout the monitoring period, the disappearance of seagrass beds
was believed the cause of cyclone hits rather than impact of HKLR project. The
seagrass bed was recolonizing since there had been a gradual increase in the size and number from
December 2018 to June 2019 after the hit of the super cyclone in September
2018. The seagrass bed area slightly
decreased from September 2019 to December 2020 (present survey) which were in normal
fluctuation.
Intertidal Soft Shore Communities
Substratum
6.5.42
Table 3.3 and
Figure 3.13 of Appendix I show the
substratum types along the horizontal transect at every tidal level in all
sampling zones. The relative distribution of substratum types was estimated by
categorizing the substratum types (Gravels & Boulders / Sands / Soft mud)
of the ten random quadrats along the horizontal transect. The distribution of
substratum types varied among tidal levels and sampling zones:
¡P
In
TC1, high percentages of ¡¥Gravels and Boulders¡¦ (H: 80%; M: 60%) were recorded
at high and mid tidal levels. Equal percentages of ¡¥Gravels and Boulders¡¦ (50%)
and ¡¥Soft mud¡¦ (50%) were recorded at low tidal level.
¡P
In
TC2, high percentages of ¡¥Gravels and Boulders¡¦ (H: 70%; M: 60%) were recorded at high and mid tidal
levels. Relatively higher percentages of ¡¥Gravels and Boulders¡¦ (50%) and ¡¥Soft mud¡¦ (40%) were recorded at low tidal level.
¡P
In
TC3, higher
percentage of ¡¥Gravels and Boulders¡¦ (H: 70%; M: 60%; L: 60%) were recorded at high, mid and
low tidal level.
¡P
In ST,
¡¥Gravels and Boulders¡¦ was the main substratum type (H: 80%; M: 70%) at high tidal level and mid tidal level.
At low tidal level, ¡¥Soft Mud¡¦ was the
main substratum type (50%) following by ¡¥Gravels and Boulders¡¦ (40%) and ¡§Sand¡¨(10%).
6.5.43
There was neither consistent
vertical nor horizontal zonation pattern of substratum type in all sampling
zones. Such heterogeneous variation should be caused by different hydrology
(e.g. wave in different direction and intensity) received by the four sampling
zones.
Soft shore communities
6.5.44
Table 3.4 of Appendix I lists the total abundance, density and number of taxon of every phylum in
this survey. A total of 11025 individuals
were recorded. Mollusca was the most abundant phylum (total abundance 10639 ind., density 355 ind. m-2, relative abundance 96.5%). The second was Arthropoda (200 ind., 7 ind. m-2,
1.8%) which followed by Sipuncula (86 ind., 3 ind. m-2, 0.8%) and Annelida (46 ind., 2 ind. m-2, 0.4%). Relatively other phyla were very low in
abundances (density <2 ind. m-2,
relative abundance £0.3%). Moreover, the most diverse phylum was Mollusca (32 taxa) followed by Arthropoda (7 taxa) and Annelida (3 taxa). There were
2 taxa recorded for Sipuncula and 1 taxon for other phyla.
6.5.45 The taxonomic
resolution and complete list of recorded fauna are shown in Annexes IV and V of Appendix I respectively.
As reported in June 2018, taxonomic revision of three potamidid snail species
was conducted according to the latest identification key published by
Agriculture, Fisheries and Conservation Department (details see AFCD, 2018),
the species names of following gastropod species were revised:
¡P
Cerithidea cingulata was revised as Pirenella asiatica
¡P
Cerithidea djadjariensis was revised as Pirenella incisa
¡P
Cerithidea rhizophorarum was revised as Cerithidea moerchii
Moreover,
taxonomic revision was conducted on another snail species while the specie name
was revised:
¡P
Batillaria bornii was revised as Clypeomorus bifasciata
6.5.46
Table 3.5 of Appendix I shows the number of individual, relative
abundance and density of each phylum in every sampling zone. The total abundance (2227 - 3176 ind.) varied
among the four sampling zones while the phyla
distributions were similar. In general, Mollusca was the most dominant phylum (no. of individuals: 2146 - 3061 ind.; relative abundance 95.8 - 97.4%; density 286 - 408 ind. m-2). Other phyla
were much lower in number of individuals. Arthropoda (35 - 61 ind.; 1.2 - 2.2%; 5 - 8 ind.
m-2), Sipuncula (15 - 35 ind.; 0.7 -
1.0%; 2 - 4 ind. m-2) were common phyla relatively. Other phyla were very low in abundance
in all sampling zones.
Dominant species in every
sampling zone
6.5.47
Table 3.6 of Appendix I lists the
abundant species in every sampling zone. In the present survey, most of the listed abundant
species were of high or very high density (>100 ind. m-2), which
were regarded as dominant species. Few of the listed species were of low to
moderate densities (42 - 100 ind. m-2). Other listed species of
lower density (<42 ind. m-2) were regarded as common species.
6.5.49
In TC2, the substratum types were
mainly 'Gravels and Boulders' at high tidal level. The rock oyster Saccostrea
cucullata (141 ind. m-2, 31%) and the
gastropod Monodonta labio
(104 ind. m-2, 23%) were dominant at high density. The gastropod Batillaria multiformis
(82 ind. m-2, 18%) were at low - moderate density. At mid tidal
level (major substratum type ¡¥Gravels and Boulders¡¦), rock oyster Saccostrea
cucullata (127 ind. m-2, 29%) was
dominant at high density. The gastropods Batillaria
zonalis (96 ind. m-2, 22%) and Monodonta labio (92
ind. m-2, 21%) were at low ¡V moderate density level. Substratum
types ¡¥Gravels and Boulders¡¦ was mainly distributed at low tidal level, rock
oyster Saccostrea cucullata (138 ind. m-2,
36%) was dominant at high density while the gastropod Monodonta
labio (88 ind. m-2, 23%) was at low ¡V
moderate density level
6.5.52
In general,
there was no consistent zonation pattern of species distribution across all
sampling zones and tidal levels. The species distribution was determined by the
type of substratum primarily. In general, rock oyster Saccostrea cucullata (2507 ind.), gastropods Monodonta labio (1262
ind.) and Batillaria multiformis
(389 ind.) were the most common species on gravel and boulders substratum.
Rock oyster Saccostrea cucullata (S: 717 ind.,
M: 752 ind.) was the most common species on sandy and soft mud substrata.
Biodiversity and abundance of
soft shore communities
6.5.53
Table 3.7 of Appendix I shows the mean values of species number, density, and
biodiversity index H¡¦ and species evenness J of soft shore communities at every tidal level
and in every sampling zone. As mentioned above, the differences among
sampling zones and tidal levels were determined by the major type of substratum primarily.
6.5.54
Among
the sampling zones, the mean species number was similar (12 ¡V 15 spp. 0.25 m-2)
among the four sampling zones. The mean densities of TC2 (423 ind. m-2)
was higher than TC1 (389 ind. m-2) followed by ST (361 ind. m-2)
and TC3 (297 ind. m-2). The higher densities of TC2 and TC1 are due
to the relatively high number of individuals in each quadrat. TC1 and ST were
relatively higher in H¡¦ (1.90 and 1.97) and followed by TC2 and TC3 (both
1.87). Comparing with TC1, TC3 and ST (all J: 0.73), TC2 (0.77) were higher in
J which were due to their higher species number and even taxa distribution.
6.5.55
In the
present survey, no clear trend of mean species number, mean density, H¡¦ and J observed among the tidal level.
6.5.56
Figures 3.14
to 3.17 of Appendix I show the temporal changes of mean species
number, mean density, H¡¦ and J at
every tidal level and in every sampling zone along the
sampling months. In general, all the biological parameters fluctuated
seasonally throughout the monitoring period. Lower mean species number and
density were recorded in dry season (December) but the mean H' and J fluctuated within a limited range.
Impact of the HKLR project
6.5.58
It was
the 33rd survey of the EM&A programme
during the construction period. Based on the results, impacts of the HKLR
project were not detected on intertidal soft shore community. Abnormal
phenomena (e.g. rapid, consistent or non-seasonal decline of fauna densities
and species number) were not recorded.
6.6.1
AFCD, 2018. Potamidid Snails in Hong Kong Mangrove. Agriculture,
Fisheries and Conservation Department Newsletter - Hong Kong Biodiversity Issue
#25, 2-11
6.6.2
Chan, K.K., Caley,
K.J., 2003. Sandy Shores, Hong Kong Field Guides 4. The Department of Ecology
& Biodiversity, The University of Hong Kong. pp 117.
6.6.3
Dai, A.Y., Yang,
S.L., 1991. Crabs of the China Seas. China Ocean Press. Beijing.
6.6.4
Dong, Y.M., 1991.
Fauna of ZheJiang Crustacea. Zhejiang Science and
Technology Publishing House. ZheJiang.
6.6.5
EPD, 1997. Technical
Memorandum on Environmental Impact Assessment Process (1st edition).
Environmental Protection Department, HKSAR Government.
6.6.6
Fauchald, K., 1977. The polychaete worms. Definitions
and keys to the orders, families and genera. Natural History Museum of Los
Angeles County, Science Series 28. Los Angeles, U.S.A..
6.6.7
Fong, C.W., 1998.
Distribution of Hong Kong seagrasses. In: Porcupine! No. 18. The School of
Biological Sciences, The University of Hong Kong, in collaboration with Kadoorie Farm & Botanic Garden Fauna Conservation
Department, p10-12.
6.6.8
Li, H.Y., 2008. The
Conservation of Horseshoe Crabs in Hong Kong. MPhil Thesis, City University of
Hong Kong, pp 277.
6.6.9
Longstaff, B.J.,
Dennison, W.C., 1999. Seagrass survival during pulsed turbidity events: the
effects of light deprivation on the seagrasses Halodule
pinifolia and Halophila
ovalis. Aquatic Botany 65 (1-4), 105-121.
6.6.10
Longstaff, B.J., Loneragan, N.R., O¡¦Donohue, M.J.,
Dennison, W.C., 1999. Effects of light deprivation on the survival and recovery
of the seagrass Halophila ovalis (R.
Br.) Hook. Journal of Experimental Marine Biology and Ecology 234 (1), 1-27.
6.6.11
Nakaoka, M., Aioi, K., 1999. Growth of seagrass Halophila ovalis at dugong trails
compared to existing within-patch variation in a Thailand intertidal flat.
Marine Ecology Progress Series 184, 97-103.
6.6.12
Pielou, E.C., 1966. Shannon¡¦s formula as a measure of species diversity: its
use and misuse. American Naturalist 100, 463-465.
6.6.13
Qi, Z.Y., 2004.
Seashells of China. China Ocean Press. Beijing, China.
6.6.14
Qin, H., Chiu, H.,
Morton, B., 1998. Nursery beaches for Horseshoe Crabs in Hong Kong. In:
Porcupine! No. 18. The School of Biological Sciences, The University of Hong
Kong, in collaboration with Kadoorie Farm &
Botanic Garden Fauna Conservation Department, p9-10.
6.6.15
Shannon, C.E.,
Weaver, W., 1963. The Mathematical Theory of Communication. Urbana: University
of Illinois Press, USA.
6.6.16
Shin, P.K.S., Li,
H.Y., Cheung, S.G., 2009. Horseshoe Crabs in Hong Kong: Current Population
Status and Human Exploitation. Biology and Conservation of Horseshoe Crabs
(part 2), 347-360.
6.6.17
Supanwanid, C., 1996. Recovery of the seagrass Halophila
ovalis after grazing by dugong. In: Kuo, J.,
Philips, R.C., Walker, D.I., Kirkman, H. (eds), Seagrass biology: Proc Int
workshop, Rottenest Island, Western Australia. Faculty of Science, The
University of Western Australia, Nedlands, 315-318.
6.6.18
Vermaat, J.E., Agawin, N.S.R., Duarte, C.M., Fortes,
M.D., Marba. N., Uri, J.S., 1995. Meadow maintenance,
growth and productivity of a mixed Philippine seagrass bed. Marine Ecology
Progress Series 124, 215-225.
6.6.19
Yang, D.J, Sun, R.P.,
1988. Polychaetous annelids commonly seen from the
Chinese waters (Chinese version). China Agriculture Press, China
Table 7.1 Summary
of Environmental Site Inspections
Date of Audit |
Observations |
Actions Taken by
Contractor / Recommendation |
Date of Observations
Closed |
18, 27 Mar 2020; 1, 8, 15, 22, 28 Apr 2020; 6, 13, 20, 29 May 2020; 3,
10, 17, 26 Jun 2020; 2, 8, 15, 22, 31 Jul 2020; 5, 12, 21, 28 Aug 2020; 2, 9,
16, 23, 29 Sep 2020; 7, 14, 21, 30 Oct 2020; 4, 11,18, 27 Nov 2020 |
1.
Gaps
of silt curtains were observed at Portion X. |
1.
The
silt curtains maintenance work is in progress at Portion X. The Contractor was reminded to maintain the silt curtains at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Nov 2020. |
27 Nov 2020 |
1. Waste was observed at S16. |
2.
The waste was
removed from S16. |
2 Dec 2020 |
2 Dec 2020 |
1.
Gaps
of silt curtains were observed/ part of silt curtains were missing at Portion
X. |
1.
The silt curtains maintenance
work is in progress at Portion X. The Contractor was reminded to maintain the
silt curtains at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Jan 2021. |
2.
General
refuse was observed at S16. |
2. The general refuse was removed from S16. |
9 Dec 2020 |
|
9 Dec 2020 |
1.
Gaps
of silt curtains were observed /part of silt curtains were missing at Portion
X. |
1.
The silt curtains
maintenance work is in progress at Portion X. The Contractor was reminded to
maintain the silt curtains properly at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Jan 2021. |
16 Dec 2020 |
1.
Gaps
of silt curtains were observed /part of silt curtains were missing at Portion
X. |
1. The silt curtains maintenance work is in progress at Portion X. The
Contractor was reminded to maintain the silt curtains properly at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Jan 2021. |
2. Waste
was observed at N1. |
2.
The waste was removed from N1. |
23 Dec 2020 |
|
23 Dec 2020 |
1. Gaps of silt curtains were observed/ part of silt curtains
were missing at Portion X. |
1.
The silt curtains
maintenance work is in progress at Portion X. The Contractor was reminded to
maintain the silt curtains properly at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Jan 2021. |
2.
Waste was accumulated at N1. |
2.
The waste was removed from N1. |
29 Dec 2020 |
|
29 Dec 2020 |
1.
Gaps
of silt curtains were observed/ part of silt curtains were missing at Portion
X. 2.
Waste was observed
at N1. |
The Contractor was recommended to: 1.
maintain
the silt curtains properly at Portion X. 2.
remove the waste at N1. |
Follow-up actions for the observations
issued for the last weekly site inspection of the reporting month will be inspected
during the next site inspection. |
Table 7.2 Summary of Environmental Site
Inspections (Landscape works) for the Contract works area
Date of Audit |
Observations |
Actions Taken by Contractor / Recommendation |
Date of Observations Closed |
16
Dec 2020 |
No particular environmental issue was recorded
during the site inspection. |
Nil. |
Nil. |
23
Dec 2020 |
No particular environmental issue was recorded
during the site inspection. |
Nil. |
Nil. |
Table 8.1 Construction
Activities for January 2021
Site Area |
Description of Activities |
Portion X and Airport
Road |
Landscaping Works |
Airport Road |
E&M Works |
Portion X |
Finishing Works for
Highway Operation and Maintenance Area |
West Portal |
Finishing Works for
Scenic Hill Tunnel Ventilation Building |
West Portal |
Extension of Security
Fencing |