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.138 (March 2024)
12 April 2024
Revision 1
Main
Contractor
Designer
|
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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 Area
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 138th Monthly EM&A report for the Contract which summarizes the monitoring results and audit findings of the EM&A programme during the reporting period from 1 to 31 March 2024.
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 |
4, 8, 14, 20, 26 and 28 March 2024 |
24-hr TSP Monitoring at AMS5 |
1, 7, 13, 19 and 25 March 2024 |
Noise Monitoring |
4, 14, 20 and 26 March 2024 |
Water Quality Monitoring |
1, 4, 6, 8, 11, 13, 15, 18, 20, 22, 25, 27 and 29 March 2024 |
Chinese White Dolphin Monitoring |
4, 5, 15 and 20 March 2024 |
Site Inspection |
6, 13, 20 and 28 March 2024 |
Mudflat Monitoring (Ecology) |
11, 12 and 13 March 2024 |
Mudflat Monitoring (Sedimentation Rate) |
25 March 2024 |
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.
Due to equipment malfunction, the result of the 24-hr TSP monitoring on 29 March 2024 was voided and substitute monitoring was scheduled on 2 April 2024. |
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:
¡P Removal of Temporary Toe Loading Platform at Portion X.
¡P New reclamation along the east coast of the approximately 23 hectares.
¡P Tunnel of Scenic Hill (Tunnel SHT) from Scenic Hill to the new reclamation, of approximately 1km in length with three (3) lanes for the east bound carriageway heading to the HKBCF and four (4) lanes for the westbound carriageway heading to the HZMB Main Bridge.
¡P An abutment of the viaduct portion of the HKLR at the west portal of Tunnel SHT and associated road works at the west portal of Tunnel SHT.
¡P An at grade road on the new reclamation along the east coast of the HKIA to connect with the HKBCF, of approximately 1.6 km along dual 3-lane carriageway with hard shoulder for each bound.
¡P Road links between the HKBCF and the HKIA including new roads and the modification of existing roads at the HKIA, involving viaducts, at grade roads and a Tunnel HAT.
¡P A highway operation and maintenance area (HMA) located on the new reclamation, south of the Dragonair Headquarters Building, including the construction of buildings, connection roads and other associated facilities.
¡P Associated civil, structural, building, geotechnical, marine, environmental protection, landscaping, drainage and sewerage, tunnel and highway electrical and mechanical works, together with the installation of street lightings, traffic aids and sign gantries, water mains and fire hydrants, provision of facilities for installation of traffic control and surveillance system (TCSS), reprovisioning works of affected existing facilities, implementation of transplanting, compensatory planting and protection of existing trees, and implementation of an environmental monitoring and audit (EM&A) program.
Table 1.1
Contact Information of Key Personnel
Party |
Position |
Name |
Telephone |
Fax |
Supervising Officer¡¦s
Representative |
(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 ¡V Ma Wan Chung Village (Tung Chung) |
352 |
500 |
AMS 6 ¡V Dragonair / CNAC (Group) Building (HKIA) |
360 |
Table 2.2 Action and
Limit Levels for 24-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 ¡V Ma Wan Chung Village (Tung Chung) |
164 |
260 |
AMS 6 ¡V Dragonair / CNAC (Group) Building (HKIA) |
173 |
260 |
Table 2.3 Air Quality
Monitoring Equipment
Equipment |
Brand and Model |
Portable direct reading dust meter (1-hour TSP) |
Sibata Digital Dust Indicator (Model No. LD-5R) |
High Volume Sampler |
Tisch Environmental Mass Flow Controlled Total Suspended Particulate (TSP) High Volume Air Sampler (Model No. TE-5170) |
Table 2.4 Locations of
Impact Air Quality Monitoring Stations
Monitoring Station |
Location |
AMS5 |
Ma Wan Chung Village (Tung Chung) |
AMS6 |
Dragonair / CNAC (Group) Building (HKIA) |
Table 2.5
Air Quality Monitoring Parameters, Frequency and Duration
Parameter |
Frequency and Duration |
1-hour TSP |
Three times every 6 days while the highest dust impact was expected |
24-hour TSP |
Once every 6 days |
(a) The HVS was installed in the vicinity of the air sensitive receivers. The following criteria were considered in the installation of the HVS.
(i) A horizontal platform with appropriate support to secure the sampler against gusty wind was provided.
(ii) The distance between the HVS and any obstacles, such as buildings, was at least twice the height that the obstacle protrudes above the HVS.
(iii) A minimum of 2 meters separation from walls, parapets and penthouse for rooftop sampler was provided.
(iv) No furnace or incinerator flues are nearby.
(v) Airflow around the sampler was unrestricted.
(vi) Permission was obtained to set up the samplers and access to the monitoring stations.
(vii) A secured supply of electricity was obtained to operate the samplers.
(viii) The sampler was located more than 20 meters from any dripline.
(ix) Any wire fence and gate, required to protect the sampler, did not obstruct the monitoring process.
(x) Flow control accuracy was kept within ¡Ó2.5% deviation over 24-hour sampling period.
(b) Preparation of Filter Papers
(i) Glass fibre filters, G810 were labelled and sufficient filters that were clean and without pinholes were selected.
(ii) All filters were equilibrated in the conditioning environment for 24 hours before weighing. The conditioning environment temperature was around 25 ¢XC and not variable by more than ¡Ó3 ¢XC; the relative humidity (RH) was < 50% and not variable by more than ¡Ó5%. A convenient working RH was 40%.
(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-5025A Calibration Kit prior to the commencement of baseline monitoring. Bi-monthly 5-point calibration of the HVS will be carried out during impact monitoring.
(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 |
76 |
37-211 |
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 |
61 |
39-104 |
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 ¡V Ma Wan Chung Village (Ma Wan Chung Resident Association) (Tung Chung) |
0700-1900 hours on normal weekdays |
When one documented complaint is received |
75 dB(A) |
Table 3.2
Noise Monitoring Equipment
Equipment |
Brand and Model |
Integrated Sound Level Meter |
RION NL-52 |
Acoustic Calibrator |
RION NC-74 |
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 1.2 m above the podium for free-field measurements at NMS5. A correction of +3 dB(A) shall be made to the free field measurements.
(b) The battery condition was checked to ensure the correct functioning of the meter.
(c) Parameters such as frequency weighting, the time weighting and the measurement time were set as follows:-
(i) frequency weighting: A
(ii) time weighting: Fast
(iii) time measurement: Leq(30-minutes) during non-restricted hours i.e. 07:00 ¡V 1900 on normal weekdays
(d) Prior to and after each noise measurement, the meter was calibrated using the acoustic calibrator for 94.0 dB(A) at 1000 Hz. If the difference in the calibration level before and after measurement was more than 1.0 dB(A), the measurement would be considered invalid and repeat of noise measurement would be required after re-calibration or repair of the equipment.
(e) During the monitoring period, the Leq, L10 and L90 were recorded. In addition, site conditions and noise sources were recorded on a standard record sheet.
(f) Noise measurement was paused during periods of high intrusive noise (e.g. dog barking, helicopter noise) if possible. Observations were recorded when intrusive noise was unavoidable.
(g) Noise monitoring was cancelled in the presence of fog, rain, wind with a steady speed exceeding 5m/s, or wind with gusts exceeding 10m/s. The wind speed shall be checked with a portable wind speed meter capable of measuring the wind speed in m/s.
(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 |
63 |
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: |
¡P Depth, m ¡P Temperature, oC ¡P Salinity, ppt ¡P Dissolved Oxygen (DO), mg/L ¡P DO Saturation, % ¡P Turbidity, NTU ¡P pH ¡P Suspended Solids (SS), mg/L |
Three times per week during mid-ebb and mid-flood tides (within ¡Ó 1.75 hour of the predicted time) |
3 (1 m below water surface, mid-depth and 1 m above sea bed, except where the water depth is less than 6 m, in which case the mid-depth station may be omitted. Should the water depth be less than 3 m, only the mid-depth station will be monitored). |
Remark:
1) Original WQM stations IS8 and SR4(N) are located within the active work area of TCNTE project and the access to the WQM stations IS8 (Coordinate: E814251, N818412) and SR4(N) (Coordinate: E814705, N817859) are blocked by the silt curtains of the Tung Chung New Town Extension (TCNTE) project. Alternative monitoring stations IS8(N) (Coordinate: E814413, N818570) and SR4(N2) (Coordinate: E814688, N817996) were proposed to replace the original monitoring stations IS8 and SR4(N). Proposal for permanently relocating the aforementioned stations was approved by EPD on 20 August 2019. The water quality monitoring has been conducted at stations IS8(N) and SR4(N2) since 21 August 2019.
2) The water quality monitoring programme was temporarily suspended during the reporting month since no marine works were scheduled or conducted, therefore no water quality monitoring was conducted.
Table 4.4
Impact Water Quality Monitoring Stations
Monitoring Stations |
Description |
Coordinates |
|
Easting |
Northing |
||
IS5 |
Impact Station (Close to HKLR construction site) |
811579 |
817106 |
IS(Mf)6 |
Impact Station (Close to HKLR construction site) |
812101 |
817873 |
IS7 |
Impact Station (Close to HKBCF construction site) |
812244 |
818777 |
IS8(N) |
Impact Station (Close to HKBCF construction site) |
814413 |
818570 |
IS(Mf)9 |
Impact Station (Close to HKBCF construction site) |
813273 |
818850 |
IS10(N) |
Impact Station (Close to HKBCF construction site) |
812942 |
820881 |
SR3(N) |
Sensitive receivers (San Tau SSSI) |
810689 |
816591 |
SR4(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 March 2024 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: March 4th / 5th |
0.0 |
0.0 |
Set 2: March 15th / 20th |
0.0 |
0.0 |
|
NWL |
Set 1: March 4th / 5th |
1.8 |
3.5 |
Set 2: March 15th / 20th |
1.7 |
3.3 |
Table 5.4 Overall dolphin encounter rates (sighting per 100 km
of survey effort) from all surveys conducted in March 2024 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 |
1.7 |
1.2 |
3.4 |
2.5 |
- 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 25 March 2024. 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 (March 2024) |
|||||
Monitoring Station |
Easting (m) |
Northing (m) |
Surface Level (mPD) |
Easting (m) |
Northing (m) |
Surface Level (mPD) |
S1 |
810291.160 |
816678.727 |
0.950 |
810291.144 |
816678.734 |
1.063 |
S2 |
810958.272 |
815831.531 |
0.864 |
810958.263 |
815831.530 |
1.029 |
S3 |
810716.585 |
815953.308 |
1.341 |
810716.587 |
815953.308 |
1.471 |
S4 |
811221.433 |
816151.381 |
0.931 |
811221.446 |
816151.384 |
1.159 |
Table 6.3 Comparison of measurement
Comparison of Measurement |
Remarks and Recommendation |
|||
Monitoring Station |
Easting (m) |
Northing (m) |
Surface Level (mPD) |
|
S1 |
-0.016 |
0.007 |
0.113 |
Level continuously increased |
S2 |
-0.009 |
-0.001 |
0.165 |
Level continuously increased |
S3 |
0.002 |
-0.000 |
0.101 |
Level continuously increased |
S4 |
-0.016 |
0.007 |
0.228 |
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 March 2024 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) |
|
1-Mar-2024 |
7.2 |
3.5 |
4.4 |
6.8 |
3.5 |
3.4 |
4-Mar-2024 |
6.8 |
3.1 |
3.8 |
6.7 |
3.3 |
4.0 |
6-Mar-2024 |
6.8 |
2.7 |
2.9 |
6.3 |
2.8 |
2.8 |
8-Mar-2024 |
6.6 |
3.3 |
1.9 |
6.7 |
3.1 |
3.0 |
11-Mar-2024 |
6.8 |
3.7 |
4.1 |
6.4 |
2.6 |
3.4 |
13-Mar-2024 |
7.0 |
3.1 |
2.8 |
6.6 |
2.5 |
2.5 |
15-Mar-2024 |
6.9 |
3.4 |
2.1 |
6.4 |
2.7 |
2.3 |
18-Mar-2024 |
6.5 |
2.8 |
1.9 |
6.4 |
2.5 |
2.2 |
20-Mar-2024 |
6.8 |
2.5 |
1.5 |
6.9 |
2.7 |
1.0 |
22-Mar-2024 |
6.7 |
2.6 |
1.3 |
6.6 |
2.7 |
1.6 |
25-Mar-2024 |
6.8 |
2.8 |
2.4 |
6.5 |
2.6 |
2.8 |
27-Mar-2024 |
7.0 |
2.9 |
2.5 |
6.6 |
2.8 |
2.0 |
29-Mar-2024 |
6.7 |
3.2 |
0.8 |
6.6 |
3.1 |
1.2 |
Average |
6.8 |
3.0 |
2.5 |
6.6 |
2.8 |
2.5 |
|
Study Site ¡V 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 of Appendix I). The horizontal shoreline of sampling zones TC1, TC2, TC3 and ST were about 250 m, 300 m, 300 m and 250 m, respectively (Figure 2.2 of Appendix I). Survey of horseshoe crabs, seagrass beds and intertidal communities were conducted in every sampling zone. The present survey was conducted in March 2024 (totally 3 sampling days 12th (for ST), 13th (for TC3), and 11th (for TC2 and 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 12th (for ST), 13th (for TC3), and 11th (for TC2 and TC1) March 2024.
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¡¦= -£U ( Ni / N ) ln ( Ni / N )(Shannon and Weaver, 1963)
J = H¡¦ / ln S (Pielou, 1966)
where S is the total number of species in the sample, N is the total number of individuals, and Ni is the number of individuals of the ith species.
6.4.1 In the event of the impact monitoring results indicating that the density or the distribution pattern of intertidal fauna and seagrass is found to be significant different to the baseline condition (taking into account natural fluctuation in the occurrence and distribution pattern such as due to seasonal change), appropriate actions should be taken and additional mitigation measures should be implemented as necessary. Data should then be re-assessed and the need for any further monitoring should be established. The action plan, as given in Table 6.5 should be undertaken within a period of 1 month after a significant difference has been determined.
Table 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 ¡V Environmental Team
IEC ¡V Independent Environmental Checker
SO ¡V Supervising Officer
Horseshoe Crabs
6.5.1 One dead bodies of horseshoe crabs , and two live specimen of horseshoe crabs were recoded in present surveys. Photo records of previously and present 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 of Appendix I. The complete survey records are presented in Annex II of Appendix I.
6.5.2 No Carcinoscorpius rotundicauda and two Tachypleus tridentatus were recorded in present survey.
6.5.3 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 ¡V 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 ¡V 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 ¡V 180mm) and TC3 (prosomal width ranged 150 ¡V 220mm), respectively. In March 2020, a mating pair of Tachypleus tridentatus was recorded in TC1 with prosomal width 123 mm and 137mm. 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.
6.5.4 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.
6.5.5 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
6.5.6 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.
6.5.7 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 2024, total of 12 individuals of juveniles Carcinoscorpius rotundicauda and Tachypleus tridentatus were found and recorded. In June 2024, total of 27 individuals of juveniles Tachypleus tridentatus were found and recorded. In September 2024, total of 2 individuals of juveniles Tachypleus tridentatus were found and recorded. In December 2024, no horseshoe crab were found. In March 2024, 2 individuals of juveniles Tachypleus tridentatus were found.
6.5.8 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.
6.5.11 Throughout the monitoring period, the search records of horseshoe crabs were fluctuated and at moderate ¡V very low level in June (Figure 3.5 and 3.6 of Appendix I). Low ¡V Very low search record was found in June 2013, totally 82 individuals of Tachypleus tridentatus and 0 ind. of Carcinoscorpius rotundicauda were found in TC1, TC3 and ST. Compare with the search record of June 2013, the numbers of Tachypleus tridentatus were gradually decreased in June 2014 and 2015 (55 ind. in 2014 and 18 ind. in 2015); the number of Carcinoscorpius rotundicauda raise to 88 and 66 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.
6.5.12 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 ¡V low search record was found in December from 2012 to 2015 (0-4 ind. of Carcinoscorpius rotundicauda and 0 ¡V 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¢XC 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 and 2024.
6.5.13 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 ¡V 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).
6.5.14 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 ¡V 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.
6.5.15 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.
6.5.16 Figure 3.7 of Appendix I shows the changes of prosomal width of Carcinoscorpius rotundicauda and Tachypleus tridentatus in TC3. As mentioned above, Carcinoscorpius rotundicauda was rarely found between September 2012 and December 2013 hence the data were lacking. In March 2014, the major size (50% of individual records between upper (top box) and lower quartile (bottom box)) ranged 40 ¡V 60 mm while only few individuals were found. From March 2014 to September 2018, the median prosomal width (middle line of whole box) and major size (whole box) decreased after March of every year. It was due to more small individuals found in June indicating new rounds of spawning. Also there were slight increasing trends of body size from June to March of next year since 2015. It indicated a stable growth of individuals. Focused on larger juveniles (upper whisker), the size range was quite variable (prosomal width 60 ¡V 90 mm) along the sampling months. Juveniles reaching this size might gradually migrate to sub-tidal habitats. 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.
6.5.17 For Tachypleus tridentatus, the major size ranged 20-50 mm while the number of individuals fluctuated from September 2012 to June 2014. Then a slight but consistent growing trend was observed from September 2014 to June 2015. The prosomal width increased from 25 ¡V 35 mm to 35 ¡V 65 mm. As mentioned, the large individuals might have reached a suitable size for migrating from the nursery soft shore to subtidal habitat. It accounted for the declined population in TC3. From March to September 2016, slight increasing trend of major size was noticed again. From December 2016 to June 2017, similar increasing trend of major size was noted with much higher number of individuals. It reflected new round of spawning. In September 2017, the major size decreased while the trend was different from previous two years. Such decline might be the cause of serial cyclone hit between June and September 2017 (to be discussed in the 'Seagrass survey' section). From December 2017 to September 2018, increasing trend was noted again. It indicated a stable growth of individuals. From September 2018 to that of next year, the average prosomal widths were decreased from 60mm to 36mm. It indicated new rounds of spawning occurred during September to November 2018. In December 2019, an individual with larger body size (prosomal width 65mm) was found in TC3 which reflected the stable growth of individuals. In March 2020, the average prosomal width (middle line of the whole box) of Tachypleus tridentatus in TC3 was 33.97mm 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 ¡V 80 mm in prosomal width, even 90 mm occasionally. The juveniles reaching this size might gradually migrate to sub-tidal habitats.
Box plot of horseshoe crab populations in ST
6.5.18 Figure 3.8 of Appendix I shows the changes of prosomal width of Carcinoscorpius rotundicauda and Tachypleus tridentatus in ST. As mentioned above, Carcinoscorpius rotundicauda was rarely found between September 2012 and December 2013 hence the data were lacking. From March 2014 to September 2018, the size of major population decreased and more small individuals (i.e. lower whisker) were recorded after June of every year. It indicated new round of spawning. Also there were similar increasing trends of body size from September to June of next year between 2014 and 2017. It indicated a stable growth of individuals. The larger juveniles (i.e. upper whisker usually ranged 60 ¡V 80 mm in prosomal width except one individual (prosomal width 107.04 mm) found in March 2017. It reflected juveniles reaching this size would gradually migrate to sub-tidal habitats.
6.5.19 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 ¡V 30 mm to 60 ¡V 70 mm. As mentioned, the large juveniles might have reached a suitable size for migrating from the nursery soft shore to subtidal habitat. From March to September 2015, the size of major population decreased slightly to a prosomal width 40 ¡V 60 mm. At the same time, the number of individuals decreased gradually. It further indicated some of large juveniles might have migrated to sub-tidal habitat, leaving the smaller individuals on shore. There was an overall growth trend. In December 2015, two big individuals (prosomal width 89.27 mm and 98.89 mm) were recorded only while it could not represent the major population. In March 2016, the number of individual was very few in ST that no box plot could be produced. In June 2016, the prosomal width of major population ranged 50 ¡V 70 mm. But it dropped clearly to 30 ¡V 40 mm in September 2016 followed by an increase to 40 ¡V 50 mm in December 2016, 40 ¡V 70 mm in March 2017 and 50 ¡V 60mm in June 2017. Based on overall higher number of small individuals from June 2016 to September 2017, it indicated another round of spawning. From September 2017 to June 2018, the major size range increased slightly from 40 ¡V 50 mm to 45 ¡V 60 mm indicating a continuous growth. In September 2018, decrease of major size was noted again that might reflect new round of spawning. Throughout the monitoring period, the larger juveniles ranged 60-80 mm in prosomal width. Juveniles reaching this size would gradually migrate to sub-tidal habitats.
6.5.20 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.
6.5.21 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 ¡V 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 ¡V 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¡V78mm). 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¡V62mm). 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).
6.5.22 It was the 47th 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
6.5.23 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 ~5500m2 in moderate vegetation coverage (30 - 40%), ~4000m2 in moderate vegetation coverage (10 - 20%), ~800m2 in moderate vegetation coverage (10 - 20%) and three ~120 - 300m2 in low to moderate vegetation coverage (10 - 20%). In TC3, 3 large patches of Halophila ovalis were found at tidal zone 1.5m above C.D. The larger strand had area ~1200m2 in moderate vegetation coverage (20 - 40%), ~1000m2 in moderate vegetation coverage (10 - 20%) and ~600m2 in moderate vegetation coverage (10 - 20%). At close vicinity to mangrove, one small sized (20m2) 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.
6.5.24 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. Moreov