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.129 (Jun 2023)
13 July
2023
Revision
0
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
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 G Wind Data
Appendix H Dolphin Monitoring
Results
Appendix I Mudflat
Monitoring Results
Appendix J Waste Flow Table
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.
ANewR Consulting Limited has been employed by HyD
as the Independent Environmental Checker (IEC) and Environmental Project Offer
(ENPO) for the Project with effective from 1 October 2022.
This is the 129th
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 30 June 2023.
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 at
AMS5 |
5, 9, 15, 21 and 27 June
2023 |
24-hr TSP Monitoring at
AMS5 |
2, 8, 14, 20,
28 and 30 June 2023 |
Noise Monitoring |
5, 15, 21 and 27 June
2023 |
Water Quality Monitoring |
2, 5, 7, 9, 12, 14, 16,
19, 21, 23, 26, 28 and 30 June 2023 |
Chinese White Dolphin
Monitoring |
5, 6, 12, 19 and 20 June
2023 |
Site Inspection |
6, 16, 20 and 30 June 2023 |
Mudflat Monitoring
(Ecology) |
2, 3, 4 and 5 June 2023 |
Mudflat Monitoring
(Sedimentation Rate) |
30 June 2023 |
The existing air quality
monitoring location AMS6 - Dragonair / CNAC (Group)
Building (HKIA) was handed over to Airport Authority Hong Kong on 31 March
2021. 1-hr and 24-hr TSP monitoring at AMS6 was temporarily
suspended starting from 1 April 2021. A new alternative air quality
monitoring location is still under processing. The sedimentation rate monitoring on 15
June 2023 was rescheduled to 30 June 2023 due to the bad weather conditions. 24-hr TSP monitoring at EM&A Station
AMS5 - Ma Wan Chung Village on 26 June 2023 was rescheduled to 28 June 2023
due to malfunction of HVS at AMS5 on 26 June 2023. |
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) |
0 |
0 |
Turbidity level |
0 |
0 |
|
Dissolved oxygen level (DO) |
0 |
0 |
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 existing air quality monitoring location AMS6 - Dragonair
/ CNAC (Group) Building (HKIA) was handed over to Airport Authority Hong Kong
on 31 March 2021. 1-hr and 24-hr TSP monitoring at AMS6 was temporarily
suspended starting from 1 April 2021. A new alternative air quality
monitoring location is still under processing.
The role and
responsibilities as the IEC of the Contract has been taken up by Mr Brian Tam instead of Mr Manson Yeung since 12
April 2021.
The role and
responsibilities as the IEC of the Contract has been taken up by Mr Adi Lee instead of Mr Brian Tam since 3 May
2022.
The role and
responsibilities as the IEC of the Contract has been taken up by Mr Brian Tam
instead of Mr Adi Lee since 25 July 2022.
The role and
responsibilities as the ENPO Leader of the Contract has been taken up by Mr
Louis Kwan from ANewR Consulting Limited instead of Mr H.Y. Hui from Ramboll Hong Kong
Limited since 1 October 2022.
The role and
responsibilities as the IEC of the Contract has been taken up by Mr James Choi
from ANewR Consulting Limited instead of Mr Brian Tam from Ramboll Hong Kong
Limited since 1
October 2022.
Future Key
Issues
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:
·
Landscape maintenance
works at SHT East Portal.
·
Removal of Temporary
Toe Loading Platform at Portion X.
·
New reclamation along
the east coast of the approximately 23 hectares.
·
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.
·
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.
·
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.
·
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.
·
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.
·
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 |
(Senior Resident
Engineer, SRE) |
Eddie Tsang |
3968 4802 |
2109 1882 |
Environmental Project Office / Independent Environmental Checker |
Environmental Project Office Leader |
Louis Kwan |
9275 0975 |
3007 8448 |
Independent Environmental Checker |
James Choi |
6122 5213 |
3007 8448 |
|
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 |
2859 5409 |
2559 0738 |
724 hours complaint
hotline |
--- |
--- |
5699 5730 |
--- |
|
Table 1.2 Construction Activities During Reporting Month
Description of Activities |
Site Area |
Landscape
maintenance works |
SHT East Portal |
Removal
of Temporary Toe Loading Platform |
Portion X |
Table 2.1 Action
and Limit Levels for 1-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 – Ma Wan Chung Village (Tung Chung) |
352 |
500 |
AMS 6 – 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 – Ma Wan Chung Village (Tung Chung) |
164 |
260 |
AMS 6 – 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 ±2.5% 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 |
36 |
9-109 |
352 |
500 |
AMS6 |
- |
- |
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 |
25 |
15-42 |
164 |
260 |
AMS6 |
- |
- |
173 |
260 |
Table 3.1 Action
and Limit Levels for Noise during Construction Period
Monitoring Station |
Time Period |
Action Level |
Limit Level |
NMS5 – 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 – 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 |
62 |
60-66 |
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 |
YSI Model 6820 (V2) YSI Pro Quatro |
Positioning Equipment |
Garmin GPS72H |
Water Depth Detector |
Lowrance x-4 |
Water Sampler |
Kahlsio Water Sampler (Vertical)
2.2 L with messenger |
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: |
·
Depth, m ·
Temperature, oC ·
Salinity, ppt ·
Dissolved Oxygen
(DO), mg/L ·
DO Saturation, % ·
Turbidity, NTU ·
pH · Suspended Solids (SS), mg/L |
Three times per week during
mid-ebb and mid-flood tides (within ± 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(N3)* |
Sensitive receivers (Tai
Ho Inlet) |
814779 |
818032 |
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 |
Remark: * The access to the WQM station
SR4(N2) (Coordinate: E814688, N817996) is blocked by the silt curtains of the
Tung Chung New Town Extension (TCNTE) project. Water quality monitoring was
temporarily conducted at alternative stations, namely SR4(N3) (Coordinate:
E814779, N818032) on 1 March 2023. Proposal for permanently relocating the
SR4(N2) was approved by EPD on 3 March 2023. The water quality monitoring has
been conducted at stations SR4(N3) since 3 March 2023. |
(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.
Table 5.3 Dolphin
encounter rates deduced from the two sets of surveys (two surveys in each set)
in June 2023 in Northeast (NEL)
and Northwest Lautau (NWL)
|
Encounter rate (STG) (no. of on-effort dolphin sightings per 100 km
of survey effort) |
Encounter rate (ANI)
(no. of dolphins from all on-effort sightings per 100 km of survey
effort) |
|
Primary Lines Only |
Primary Lines Only |
||
NEL |
Set 1: June 5th
/ 6th / 12th |
0.0 |
0.0 |
Set 2: June 19th
/ 20th |
0.0 |
0.0 |
|
NWL |
Set 1: June 5th
/ 6th / 12th |
0.0 |
0.0 |
Set 2: June 19th
/ 20th |
0.0 |
0.0 |
Table 5.4 Overall dolphin
encounter rates (sighting per 100 km of survey effort) from all surveys
conducted in June 2023 on primary lines
only as well as both primary lines and secondary lines in Northeast and
Northwest Lantau
|
Encounter rate (STG) (no.
of on-effort dolphin sightings per 100 km of survey effort) |
Encounter rate (ANI)
(no. of dolphins from all on-effort
sightings per 100 km of survey effort) |
||
Primary Lines Only |
Both Primary and Secondary Lines |
Primary Lines Only |
Both Primary and Secondary Lines |
|
Northeast Lantau |
0.0 |
0.0 |
0.0 |
0.0 |
Northwest Lantau |
0.0 |
0.0 |
0.0 |
0.0 |
-
Buckland, S. T., Anderson, D. R., Burnham, K. P., Laake,
J. L., Borchers, D. L., and Thomas, L.
2001. Introduction to
distance sampling: estimating abundance of biological populations. Oxford University Press, London.
-
Hung, S. K. 2021. Monitoring of Marine Mammals in Hong
Kong waters: final report (2020-21).
An unpublished report submitted to the Agriculture, Fisheries and
Conservation Department, 154 pp.
-
Jefferson, T. A. 2000. Population biology of the Indo-Pacific
hump-backed dolphin in Hong Kong waters.
Wildlife Monographs 144:1-65.
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 30 June 2023. 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
(June 2023) |
|||||
Monitoring
Station |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
S1 |
810291.160 |
816678.727 |
0.950 |
810291.182 |
816678.709 |
1.123 |
S2 |
810958.272 |
815831.531 |
0.864 |
810958.271 |
815831.525 |
0.970 |
S3 |
810716.585 |
815953.308 |
1.341 |
810716.586 |
815953.314 |
1.440 |
S4 |
811221.433 |
816151.381 |
0.931 |
811221.447 |
816151.381 |
1.124 |
Table 6.3 Comparison of
measurement
Comparison of Measurement |
Remarks and Recommendation |
|||
Monitoring
Station |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
|
S1 |
0.022 |
-0.018 |
0.173 |
Level continuously
increased |
S2 |
-0.001 |
-0.006 |
0.106 |
Level continuously
increased |
S3 |
0.001 |
0.006 |
0.099 |
Level continuously
increased |
S4 |
0.014 |
0.000 |
0.193 |
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 June 2023 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)
|
Mid Ebb Tide |
Mid Flood Tide |
||||
DO (mg/L) |
Turbidity (NTU) |
SS (mg/L) |
DO (mg/L) |
Turbidity (NTU) |
SS (mg/L) |
|
2-Jun-2023 |
6.72 |
3.13 |
2.60 |
6.83 |
3.33 |
2.00 |
5-Jun-2023 |
6.54 |
4.43 |
3.53 |
6.07 |
4.08 |
4.10 |
7-Jun-2023 |
6.08 |
4.20 |
5.35 |
5.73 |
3.98 |
5.80 |
9-Jun-2023 |
6.28 |
4.45 |
3.58 |
5.98 |
4.50 |
3.45 |
12-Jun-2023 |
6.40 |
4.33 |
4.63 |
6.64 |
4.50 |
5.20 |
14-Jun-2023 |
6.61 |
4.25 |
4.73 |
6.83 |
4.55 |
4.15 |
16-Jun-2023 |
5.83 |
3.60 |
2.78 |
5.72 |
3.43 |
1.73 |
19-Jun-2023 |
6.55 |
3.80 |
3.70 |
6.17 |
3.73 |
3.35 |
21-Jun-2023 |
6.81 |
3.70 |
2.85 |
6.37 |
3.63 |
3.70 |
23-Jun-2023 |
7.28 |
4.13 |
5.18 |
6.95 |
3.65 |
4.53 |
26-Jun-2023 |
7.08 |
3.78 |
3.28 |
6.84 |
3.63 |
1.93 |
28-Jun-2023 |
6.52 |
3.53 |
4.28 |
6.65 |
3.68 |
4.73 |
30-Jun-2023 |
6.76 |
4.05 |
4.58 |
7.17 |
3.68 |
4.25 |
Average |
6.57 |
3.95 |
3.93 |
6.46 |
3.87 |
3.76 |
|
Study Site – Tung
Chung Bay and San Tau
6.3.1 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). 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). Survey of horseshoe crabs, seagrass beds and intertidal communities
were conducted in every sampling zone. The present survey was conducted in June
2023 (totally 4 sampling days 2nd (for ST), 3rd (for
TC3), 4th (for TC2) and 5th (for TC1).
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 2nd (for ST), 3rd (for TC3), 4th (for TC2) and 5th (for TC1) June 2023, which were sunny days.
Seagrass Beds
Intertidal Soft Shore Communities
Field Sampling
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.
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’= -Σ ( 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 6.5 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 – Environmental Team
IEC – Independent Environmental Checker
SO – Supervising Officer
Horseshoe Crabs
6.5.1 In total of 27 individuals of Tachypleus tridentatus were found in present survey. The recorded individuals were distributed within areas of ST and TC3. All 27
findings were juvenile specimens. Photo records of previously observed horseshoe crab is shown in Figure 3.1 of Appendix I and the present survey result regarding horseshoe crab are presented in
Table 3.1. The complete survey
records are presented in Annex II of Appendix I .
6.5.2 No Carcinoscorpius rotundicauda was recorded in present survey.
6.5.3 For Tachypleus tridentatus,
18 individuals with average body size 59.09 mm (prosomal width ranged 46.21
– 77.25 mm) were found in ST and 9 individuals with average body size 66.6
(prosomal width ranged 46.5-84.13 mm) were found in TC3 in present survey. The
search records in ST (3.0 ind. hr-1. Person-1) and in TC3 (1.5 ind. Hr-1.
Person-1).
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, two mating pairs of Tachypleus tridentatus with large body
sizes (male 150mm and Female 200mm; Male 180mm and Female 220mm) were 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 the mating pair 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 – September)
because tiny individuals (i.e. newly hatched) were usually recorded in June and
September every year (Figure 3.3 of Appendix I). One mating pair
was found in June 2022. 3 adult individuals (prosomal width >100mm) of Carcinoscorpius rotundicauda
were recorded in September 2022 survey, with one alive, one dead in TC3 and
one dead in TC2. June 2022, 7 large
individuals (prosomal width >100mm) of Carcinoscorpius
rotundicauda was recorded (prosomal width ranged
131.4mm - 140.3mm) in TC3. 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 – 310mm) of Carcinoscorpius rotundicauda
were observed in TC2. In June 2019, there were 3 and 7 large individuals of
Tachypleus tridentatus
recorded in ST (prosomal width ranged 140 – 180mm) and TC3
(prosomal width ranged 150 – 220mm),
respectively. In March 2020, a mating pair of Tachypleus
tridentatus was recorded in TC1 with prosomal
width 123 mm and 137mm. Base 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.
6.5.5
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 crab’s 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.
6.5.6
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
6.5.7
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.
6.5.8
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 and TC3. From December 2018 to September 2019, the search records of Carcinoscorpius rotundicauda change from very low to low while the change of Tachypleus tridentatus was similar
during this period. Relatively higher population fluctuation of Carcinoscorpius rotundicauda
was observed in TC3. From March 2020 to September 2020, the search records of both species, Carcinoscorpius rotundicauda and Tachypleus
tridentatus, were increased to moderate level in
ST. However, the search records of both species, Carcinoscorpius rotundicauda and Tachypleus
tridentatus, were decreased from very
low to none in TC3 in this
period. From March 2021 to September 2021, the search records of both species, Carcinoscorpius rotundicauda and Tachypleus
tridentatus, were kept at low-moderate level in both ST
and TC3. It is similar to the previous findings of June. It shows
another growing phenomenon of horseshoe crabs and it may due to the weather variation of starting of
wet season. The survey
results were different from previous findings that there were usually higher
search records in September. One possible reason was that September of 2021 was one of the hottest month in Hong Kong in record.
As such, hot and shiny weather decreased
horseshoe crab activity. In December 2021, no juvenile was recorded
similar to the some previous in December due to the season. In March 2022, only
juvenils recorded in both ST
and TC3, no adult specimen was observed. In June 2022, total of 13 individuals
of Carcinoscorpius rotundicauda
and Tachypleus tridentatus
were found, with 6 juveniles, 6 adults and 1 died recorded. In September 2022,
total of 7 individuals of were found, with 4 juveniles, 3 adults (1 alive and 2
died) recorded. In March 2023, total of 12 individuals of juveniles Carcinoscorpius rotundicauda
and Tachypleus tridentatus
were found and recorded. In June 2023, total of 27 individuals of juveniles Tachypleus tridentatus
were found and recorded.
6.5.9 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.
6.5.12 Throughout the monitoring period, the search
records of horseshoe crabs were fluctuated and at moderate – very low level in
June (Figure 3.5 and 3.6 of Appendix I). Low – 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 ind. 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. In December 2020, the number of Carcinoscorpius rotundicauda and Tachypleus tridentatus
greatly decreased to 3 ind. and 7 ind., respectively. In March 2022, the number of Carcinoscorpius rotundicauda and Tachypleus tridentatus
gradually decreased to 7 ind. and 2 ind., respectively in comparing with the
March of previous record. The drop of abundance may be related to the unusual
cold weather in the beginning of March 2022. Throughout the monitoring period,
similar distribution of horseshoe crab population was found.
6.5.13 The search record of horseshoe crab declined
obviously in all sampling zones during dry season especially December (Figure 3.5 and 3.6 of Appendix I) throughout the monitoring period. Very low – 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-1 person-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°C 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. No record of houseshoe crab was
recorded in December 2022.
6.5.14 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 – 49.81 mm), it indicated that breeding and
spawning of this species had occurred about 3 years ago along the coastline of
Tung Chun 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).
6.5.15
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 conitued to grow and reach about 55mm. The population size of Tachypleus tridentatus slightly decreased in ST from March 2021 to March 2022 and the mean
proposal width of them increased to about 77.59mm.
6.5.16
In recent
year, the 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 increased in 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.
6.5.17 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 – 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 – 90 mm) along the sampling months. Juveniles
reaching this size might gradually migrate to sub-tidal habitats. In March
2022, 2 Carcinoscorpius rotundicauda with body size (prosomal width
52.21-54.63mm) were found in TC3. The findings were relatively lower than the
previous record in March. This can due to the natural variation caused by
multi-environmental factors.
6.5.18 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 – 35 mm to 35 – 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 33.97mm which is smaller than
that in December 2019. It was in normal fluctuation. From June 2020 to December 2020,
no horseshoe crab was recorded in TC3. In Sep 2021, only one Tachypleus tridentatus with body size (prosomal width 38.78mm) was
found in TC3. The decrease in the species population was considered to be
related to hot weather in September, which may affect their activity. Across the whole monitoring period, the larger
juveniles (upper whisker) usually reached 60 – 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
6.5.19 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 – 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.
6.5.20 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 – 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 – 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 – 70 mm. But it dropped clearly to 30 – 40 mm in September 2016 followed by an
increase to 40 – 50 mm in December 2016, 40 – 70 mm in March 2017 and 50 – 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 – 50 mm to 45 – 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 60-80 mm in prosomal width. Juveniles reaching this size would gradually
migrate to sub-tidal habitats.
6.5.21 As a summary for horseshoe crab populations
in TC3 and ST, there were spawning ground 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.
6.5.22
In March
2019 to June 2019 and Dec 2021, 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 – 55mm). It indicated the natural stable growth
of the horseshoe crab juveniles. In December 2020, 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 – 56mm). It showed the natural mortality and
seasonal variation of horseshoe crab. In June 2022, the population size of both horseshoe
crab species in ST was kept as low-moderate
level while their body sizes were mostly in small to medium range (~51–78mm). In September 2022, the
population size of both horseshoe crab species in TC3 and ST was kept as low-moderate level while their body
sizes were mostly in small to medium range (~56–62mm). In September 2022, the population size of both horseshoe
crab species in TC3 and ST was kept as
low-moderate level while their body sizes were mostly in small to medium
range (~44-79mm).
6.5.23 It was the 44th 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
6.5.24 Two seagrass species Halophila ovalis and Zostera japonica were found in present survey. Halophila ovalis was found in TC3 and ST and Zostera japonica was found only in ST. In ST, there were six large sized of Halophila ovalis found
at tidal zone 1.5m above C.D nearby mangroves plantation. The larger strand had area ~8400m2 in
moderate vegetation coverage (40-50%), ~5200m2 in
moderate vegetation coverage (30 - 40%),~1900m2 in
moderate vegetation coverage (20 - 30%) and three ~600 - 200m2 in
low to moderate vegetation coverage (10 - 30%). In TC3, 3 large patches of Halophila ovalis were found at tidal zone 1.5m above C.D. The
larger strand had area ~2200m2 in
moderate vegetation coverage (40 - 70%), ~1900m2 in
moderate vegetation coverage (30 - 60%) and ~800m2 in moderate
vegetation coverage (20-50%). At close vicinity to mangrove, one small sized (35m2) of Zostera japonica beds were
observed at tidal zone 2.0m above C.D in ST. Table 3.2 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.
6.5.25 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 – 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.
6.5.26 According to the
previous results, majority of seagrass bed was confined in ST, the temporal
change of both seagrass species was investigated in details:
Temporal variation of seagrass beds in ST
6.5.27
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 March 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 March 2021, while no patch of Zostera japonica was found. From June 2021, the species was recorded
again in area of 45m2. The recorded area of the seagrass bed in
September 2021 survey was slightly decreased to 15m2.
6.5.28
For Halophila ovalis, it was recorded as 3 – 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 – 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 – 8thSeptember: 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.
6.5.29
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
6.5.30
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.
6.5.31
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).
6.5.32
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.
6.5.33
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
6.5.34
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
6.5.35
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 occured between September and December 2014, strong water
current (e.g. cyclone) or deteriorated water
qualities (e.g. high turbidity) was the possible cause.
6.5.36
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 in22 – 23rd, Aug.; Pakhar in 26 – 27th, Aug.)
(Online database of Hong Kong Observatory) All of them reached signal 8 or above,
especially Hato with highest signal 10.
6.5.37
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.
6.5.38
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– 85%; March 2019: 50 – 100% and
June 2019: 60 – 100%). Relatively, the whole recolonization
process would occur slower than the previous round (more than 2 years). From
September 2019 to March 2021, the seagrass bed area in ST slightly decreased
from 1200 m2 to 942.05 m2, which were in normal fluctuation. From March 2021 to December 2021, the seagrass
bed area in ST decreased from 942.05 m2 to 680m2, which were in normal fluctuation. In March 2022, the seagrass bed area in ST
increased significantly to approximately 2040 m2, which believed to
be related to more rain in current dry season. It was observed that the brown filemental algae bloom occurred at ST site in March 2022.
Distribution of the algae was overlap with seagrass beds, mainly the species Halophila ovalis and the algae was grown over the top of the
seagrass. In some areas, the brown filemental
algae full covered the seagrass bed, refer to Figure 3.9. The seagrass was
still alive when checked during the field survey. Whether the algae bloom will kill seagrass in longer
period time is unknown. The seagrass distritrution
and health condition should be checked in coming June monitoring. The algae
bloom of the brown filemental algae at the seagrass
bed is disappeared as observed in June 2022, refer to Figure 3.9. Seagrass in
December 2022 and September 2022 have decreased compare to June 2022 due to
normal seasonal change. Seagrass in March 2023
have increased compare to previous quarter due to normal seasonal change.
Seagrass in June 2023 have further increased around 20% compared to previous
period.
Impact of the HKLR project
6.5.39
It was the
44th 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 decreased from March 2021 to December 2021, which
were in normal fluctuation. It is observed that the seagrass Halophila
ovalis covered larger area than before. Total seagrass bed area
significantly increased from March 2022 to June 2022 and slightly reduced in
September 2022. Seagrass in June 2023 have increased compare to previous
quarter due to normal seasonal change.
Intertidal Soft Shore
Communities
Substratum
6.5.40
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:
·
In TC2, high
percentages of ‘Gravels and Boulders’ (90%) was
recorded at high tidal level, following by ‘Sands’ (5%) and ‘Soft mud’ (5%). At
mid tidal level, ‘Gravels and Boulders’ was the
main substratum type (70%), following by ‘Sands’ (20%) and ‘Soft mud’ (10%). At low tidal level, ‘Soft mud’
covered 80% , ‘Soft
mud’ and ‘Sands ’ covered 20% of the
transect.
·
In TC3, higher
percentage of ‘Gravels and Boulders’ was
recorded at high tidal level (65%). At mid tidal levels, ‘‘Gravels and Boulders’ was the
main substratum type (50%), following by ‘Soft mud ’ (30%)
and ‘Sands’ (20%). At low tidal level, ‘Soft mud’
covered 70% of the transect.
·
In ST, ‘Gravels and Boulders’ was the
main substratum type (65%) at
high tidal level. At mid tidal levels, ‘Gravels and Boulders’ and ‘Soft
mud’ was the main substratum type (50% and 30%), following by ‘Sand’ (20%). At
low tidal level, ‘Soft mud’ was the main substratum type (90%) and ‘Sands’ covered 10% of the
transect.
6.5.41
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
·
Cerithidea cingulata was revised as Pirenella asiatica
·
Cerithidea djadjariensis was revised as Pirenella incisa
·
Cerithidea rhizophorarum was revised as Cerithidea moerchii
Moreover, taxonomic revision
was conducted on another snail species while the specie name was revised:
·
Batillaria bornii was revised as Clypeomorus bifasciata
6.5.44
In March 2021, an increased number of sea
slugs and their eggs were observed in all sampling zones. It may due to the
breeding season of sea slug and the increased of algae on the intertidal.
6.5.45
Table 3.5 of Appendix I shows the number of individuals, relative abundance and density of each phylum in every sampling zone. The total abundance (1,671 - 2,522 ind.) varied among the four sampling zones
while the phyla distributions were similar. In general, Mollusca was the most dominant phylum (no. of individuals: 1,526 - 2,307 ind.; relative abundance 83.9 – 91.5%; density 203 - 308 ind. m-2). Other phyla were much lower in number of individuals. Arthropoda (88- 310 ind.; 4.4 – 13.9%; 12 - 41 ind. m-2) was common phyla relatively. Other phyla were very low in abundance in all sampling zones.
Dominant species in every sampling zone
6.5.46
Table 3.6 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 – 95 ind. m-2). Other listed species
of lower density (<42 ind. m-2) were regarded as common species.
6.5.48
In TC2, the
substratum types were mainly ' Gravels and
Boulders' at high tidal
level. The rock oyster Saccostrea cucullata (136 ind. m-2, 39%) was dominant at high density. The gastropod Monodonta labio (59 ind. m-2, 17%) was dominant at low to moderate density. ), the Batillaria multiformis (38 ind. m-2, 11%) was dominant at low densities. At mid tidal level (main substratum types ‘Soft mud’ and ‘Gravels and
Boulders’), rock oyster Saccostrea cucullata (92 ind. m-2, 29%), gastropods Monodonta
labio (62 ind. m-2, 17%) and Batillaria zonalis (48
ind. m-2, 15%) were dominant at low to moderate densities. Substratum types ‘Soft Mud’ were mainly
distributed at low tidal level, the Barbatia virescens (43 ind. m-2, 19%) was dominant
at low to moderate densities, the Batillaria multiformis (33 ind. m-2, 15%) were of lower densities, regarded as common species.
6.5.49
In TC3, the substratum
type was mainly ‘Gravels and Boulders’ at high tidal level. The rock oyster Saccostrea
cucullata (144 ind. m-2, 40%) was of dominant
species at high density and the gastropod Monodonta
labio (92 ind. m-2, 21%) was of low to moderate density. At mid tidal level (main substratum types ‘Soft mud’), the rock
oyster Saccostrea cucullata (83 ind. m-2,
24%) was of dominant species at low to moderate density. The gastropod Monodonta
labio (45 ind. m-2, 13%) was at low
density level. At low tidal level, the major substratum type was ‘Soft mud’.
The Lunella granulate 53 ind. m-2, 18%), the Batillaria multiformis (47 ind. m-2, 16%), Batillaria zonalis (42 ind. m-2, 14%) and the Barbatia virescens (53 ind. m-2, 18%) at lower
density.
6.5.51
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 (876 ind.), gastropods Monodonta labio (468
ind.) and Batillaria multiformis (165 ind.) were the most common species on
gravel and boulders substratum. Batillaria zonalis (142
ind.) was the most common species on sands and soft
mud substrata.
Biodiversity and abundance of soft shore communities
6.5.52
Table 3.7 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.
6.5.53
Among the
sampling zones, the mean species number was varied from 14 - 21 spp. 0.25 m-2
among the four sampling zones. The mean densities of TC3 (336 ind. m-2) was higher than ST (307 ind. m-2) followed by TC2 (298 ind. m-2) and TC1 (223 ind. m-2). The higher densities of TC3 and ST are due to the relatively high number
of individuals in each quadrat. The mean H’ for TC2 was 2.23, TC3 was 2.27, TC1
was 2.07 and ST were 2.13, followed by while the mean J of TC2 and ST were 0.8,
which were slightly higher than TC3 (0.77) and TC1. This can be due to the relatively non-even taxa distribution.
6.5.54
In the
present survey, no clear trend of mean species number, mean density, H’ and J observed among the tidal level.
Impact of the HKLR
project
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 |
6 June 2023 |
No particular environmental issue was recorded during the
site inspection. |
N.A. |
N.A. |
|
No
particular environmental issue was recorded during the site inspection. |
N.A. |
N.A. |
20 June 2023 |
No particular environmental issue was recorded during the
site inspection. |
N.A. |
N.A. |
30 June 2023 |
No particular environmental issue was recorded during the
site inspection. |
N.A. |
N.A. |
Table 8.1 Construction
Activities for July 2023
Site Area |
Description of Activities |
SHT East Portal |
Landscape maintenance
works |
Portion X |
Removal of Temporary Toe
Loading Platform |