Contract No. HY/2011/03
Hong
Kong-Zhuhai-Macao Bridge Hong Kong Link Road
Section between Scenic
Hill and Hong Kong Boundary Crossing Facilities
Quarterly EM&A Report
No. 32 (June 2020 to August 2020)
28 September 2020
Revision 0
Main Contractor Designer
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 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.
Meinhardt Infrastructure and Environment Limited has been 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 provide environmental team services to the Contract with
effective from 1 August 2020. Ramboll Hong Kong Limited was employed by HyD as the Independent Environmental Checker (IEC) and
Environmental Project Office (ENPO) for the Project.
This
is the thirty-second Quarterly 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 June 2020 to 31 August 2020.
Environmental
Monitoring and Audit Progress
The EM&A programme were undertaken in
accordance with the Updated EM&A Manual for HKLR (Version 1.0). A summary
of the monitoring activities during this reporting period is presented as
below:
Monitoring Activity
|
Monitoring
Date
|
Jun 2020
|
Jul 2020
|
Aug 2020
|
Air
Quality
|
1-hr
TSP at AMS5 and AMS6
|
2,
8, 12, 18, 24 and 30
|
6,
10, 16, 22 and 28
|
3,
7, 13, 20, 25 and 31
|
24-hr
TSP at AMS5
|
1,
5, 11, 18 and 29
|
3,
9, 15, 21, 27 and 31
|
6,
12, 18, 24 and 28
|
24-hr
TSP at AMS6
|
1,
5, 11, 17, 23 and 29
|
Noise
|
2,
8, 18, 24 and 30
|
6,
16, 22 and 28
|
3, 13, 20, 25 and 31
|
Water Quality
|
Not
applicable.(see remark 1)
|
Not
applicable.(see remark 1)
|
Not
applicable.(see remark 1)
|
Chinese
White Dolphin
|
Not
applicable.(see remark 1)
|
Not
applicable.(see remark 1)
|
Not applicable.(see
remark 1)
|
Mudflat Monitoring (Ecology)
|
17, 19, 22 and 23
|
-
|
-
|
Mudflat Monitoring (Sedimentation rate)
|
5
|
-
|
-
|
Site Inspection
|
3,
10, 17 and 26
|
2,
8, 15, 22 and 31
|
5,
12, 21 and 28
|
Remarks: 1) Water quality monitoring and dolphin
monitoring were temporarily suspended during the reporting period.
Due to power failure, 24-hr TSP monitoring on 17
June 2020 at AMS5 was rescheduled to 18 June 2020.
Due to malfunction of high volume sampler (HVS) at
AMS5, the 24-hr TSP monitoring on 23 June 2020 was cancelled. Competent person
repaired the HVS on 30 June 2020. The 24-hr TSP monitoring on 29 June 2020 at
AMS5 was rescheduled to 30 June 2020.
Due to adverse weather
condition on 19 August 2020 (Tropical Cyclone Warning Signal No.3 or above was
hoisted by HKO), 1-hr TSP monitoring at AMS5 - Ma Wan Chung Village and AMS6 - Dragonair / CNAC (Group) Building (HKIA) and noise
monitoring at NMS5 - Ma Wan Chung Village were rescheduled to 20 August 2020.
Breaches of Action and Limit Levels
A
summary of environmental exceedances for this reporting period 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)
|
Not
applicable. (see remark 1)
|
Not
applicable. (see remark 1)
|
Turbidity
level
|
Not
applicable. (see remark 1)
|
Not
applicable. (see remark 1)
|
Dissolved
oxygen level (DO)
|
Not
applicable. (see remark 1)
|
Not
applicable. (see remark 1)
|
Dolphin Monitoring
|
Quarterly
Analysis (Jun 2020 to August 2020)
|
Not
applicable. (see remark 2)
|
Not
applicable. (see remark 2)
|
Remarks:
1) Water quality monitoring was temporarily
suspended during the reporting period. Thus, no water quality monitoring
results and exceedances from June 2020 to August 2020 are presented.
2) Dolphin monitoring was temporarily suspended
during the reporting period. Thus, no quarterly analysis of dolphin monitoring
results and exceedances from June 2020 to August 2020 are presented.
Implementation of Mitigation Measures
Site
inspections were carried out to monitor the implementation of proper
environmental pollution control and mitigation measures for the Project.
Potential environmental impacts due to the construction activities were
monitored and reviewed.
Complaint Log
There
was one complaint received in relation to the environmental impacts during this
reporting period.
Notifications of Summons
and Prosecutions
There
were no notifications of summons or prosecutions received during this reporting
period.
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.
A
new water quality monitoring team has been employed for carrying out water
quality monitoring work for the Contract starting from 23 August 2017. Due to
marine work of the Expansion of Hong Kong International Airport into a
Three-Runway System (3RS Project), original locations of water quality
monitoring stations CS2, SR5 and IS10 are enclosed by works boundary of 3RS
Project. Alternative impact water quality monitoring stations, naming as
CS2(A), SR5(N) and IS10(N) was approved on 28 July 2017 and were adopted
starting from 23 August 2017 to replace the original locations of water quality
monitoring for the Contract.
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.
1.1.2
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.
1.1.3
China State Construction
Engineering (Hong Kong) Ltd. was awarded by Highways Department (HyD) as the Contractor to undertake the construction works
of Contract No. HY/2011/03. 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 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. The works area WA5 and WA7 were
handed over to other party on 22 June 2013 and 28 February 2018 respectively.
The works area WA3 and WA4 were handed over to Highways Department on 23
December 2019 and 14 March 2019 respectively. Figure 1.1 shows the project site boundary. The
works areas are shown in Appendix
C.
1.1.1
BMT Hong Kong Limited was appointed by the Contractor to implement the
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.
1.1.2 Meinhardt Infrastructure and
Environment Limited has been 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 provide environmental team services to the Contract with
effective from 1 August 2020. Ramboll Hong
Kong Limited was employed by HyD as the Independent
Environmental Checker (IEC) and Environmental Project Office (ENPO) for the
Project. The project organization with regard to the
environmental works is provided in Appendix A.
1.1.3
This is the thirty-second Quarterly Environmental Monitoring and Audit (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
June 2020 to 31 August 2020.
1.2.1 The project organization structure and lines of
communication with respect to the on-site environmental management structure
with the key personnel contact names and numbers are shown in Appendix A.
1.3
Construction Programme
1.3.1 A copy
of the Contractor¡¦s construction programme is
provided in Appendix B.
1.4
Construction
Works Undertaken During the Reporting Period
1.4.1 A
summary of the construction activities undertaken during this reporting period
is shown in Table 1.1. The Works
areas of the Contract are showed in Appendix C.
Table 1.1 Construction
Activities during Reporting Period
Description of Activities
|
Site Area
|
Landscaping works
|
Portion X and Airport Road
|
Works
for diversion
|
Airport Road
|
Establishment
of Site Access
|
Airport Road / Airport Express Line/ East
Coast Road
|
E&M
works
|
Airport Road
|
G.I.
Works at Maintenance Track
|
Portion X
|
Finishing works for Highway Operation and
Maintenance Area Building
|
Portion X
|
Finishing works for Scenic Hill Tunnel
West Portal Ventilation building
|
West Portal
|
Extension of Security Fencing
|
West Portal
|
Removal of Temporary Bus Stop and
Construction of Pedestrian Footpath
|
Tung Yiu Road
|
2.1
Summary of EM&A Requirements
2.1.1
The EM&A programme requires environmental
monitoring of air quality, noise, water quality, dolphin monitoring and mudflat
monitoring as specified in the approved EM&A Manual.
2.1.2 A summary of Impact
EM&A requirements is presented in Table
2.1. The
locations of air quality, noise and water quality monitoring stations are shown
as in Figure 2.1. The
transect line layout in Northwest and Northeast Lantau Survey Areas is
presented in Figure 2.2.
Table 2.1 Summary
of Impact EM&A Requirements
Environmental
Monitoring
|
Description
|
Monitoring
Station
|
Frequencies
|
Remarks
|
Air Quality
|
1-hr TSP
|
AMS 5 & AMS
6
|
At least 3 times every 6 days
|
While the
highest dust impact was expected.
|
24-hr TSP
|
At least once every 6 days
|
--
|
Noise
|
Leq (30mins),
L10 (30mins) and
L90 (30mins)
|
NMS 5
|
At least once per week
|
Daytime on normal weekdays
(0700-1900 hrs).
|
Water Quality
|
¡P Depth
¡P Temperature
¡P Salinity
¡P Dissolved
Oxygen (DO)
¡P Suspended
Solids (SS)
¡P DO
Saturation
¡P Turbidity
¡P pH
|
¡P Impact
Stations:
IS5, IS(Mf)6, IS7, IS8/IS8(N), IS(Mf)9 & IS10(N),
¡P Control/Far
Field Stations:
CS2(A) & CS(Mf)5,
¡P Sensitive
Receiver Stations:
SR3(N), SR4(N)/ SR4(N2), SR5(N), SR10A(N) &
SR10B(N2)
|
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).
|
Dolphin
|
Line-transect Methods
|
Northeast Lantau survey
area and Northwest Lantau survey area
|
Twice
per month
|
--
|
Mudflat
|
Horseshoe crabs, seagrass beds, intertidal soft shore communities,
sedimentation rates and water quality
|
San Tau and Tung Chung Bay
|
Once every 3 months
|
--
|
Remarks:
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) 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.
2) The water quality monitoring programme
and dolphin monitoring programme were temporarily suspended during the
reporting period, since no marine works were scheduled or conducted.
2.2
Action and
Limit Levels
2.2.1
Table 2.2 presents the Action
and Limit Levels for the 1-hour TSP, 24-hour TSP and noise level.
Table 2.2 Action and
Limit Levels for 1-hour TSP, 24-hour
TSP and Noise
Environmental Monitoring
|
Parameters
|
Monitoring Station
|
Action Level
|
Limit Level
|
Air
Quality
|
1-hr
TSP
|
AMS
5
|
352 µg/m3
|
500 µg/m3
|
AMS
6
|
360 µg/m3
|
24-hr
TSP
|
AMS
5
|
164 µg/m3
|
260 µg/m3
|
AMS
6
|
173 µg/m3
|
Noise
|
Leq (30 min)
|
NMS 5
|
When
one documented complaint is received
|
75
dB(A)
|
2.2.2 The Action and Limit Levels for water quality monitoring are given as in
Table 2.3.
Table 2.3 Action
and Limit Levels for Water Quality
Parameter
(unit)
|
Water Depth
|
Action
Level
|
Limit Level
|
Dissolved Oxygen (mg/L)
|
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. Therefore, the amended Action and Limit
Levels are applied for the water monitoring results obtained on and after 25
March 2013.
2.2.3
The Action and Limit Levels
for dolphin monitoring are shown in Tables
2.4 and 2.5.
Table 2.4 Action
and Limit Level for Dolphin Impact Monitoring
|
North Lantau
Social Cluster
|
NEL
|
NWL
|
Action Level
|
STG < 70% of baseline
&
ANI < 70% of baseline
|
STG < 70% of baseline
&
ANI < 70% of baseline
|
Limit Level
|
STG < 40% of baseline
&
ANI < 40% of baseline
|
Remarks:
(1)
STG means quarterly average encounter rate of
number of dolphin sightings.
(2)
ANI means quarterly average encounter rate of total
number of dolphins.
(3)
For North Lantau Social Cluster, AL will be
triggered if either NEL or NWL fall below the criteria; LL will be triggered if
both NEL and NWL fall below the criteria.
Table 2.5 Derived
Value of Action Level (AL) and Limit Level (LL)
|
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 average encounter rate of
number of dolphin sightings.
(2)
ANI means quarterly average encounter rate of
total number of dolphins.
(3)
For North Lantau Social Cluster, AL will be
triggered if either NEL or NWL fall below the criteria; LL will be triggered if
both NEL and NWL fall below the criteria.
2.3.1 The Event Actions Plans for air quality, noise, water quality, dolphin
monitoring and mudflat monitoring and Action Plan for Landscape Works are
annexed in Appendix D.
2.4.1 Environmental mitigation measures for the
contract were recommended in the approved EIA Report. Appendix E lists the
recommended mitigation measures and the implementation status.
3
Environmental Monitoring and Audit
3.1
Implementation of Environmental Measures
3.1.1
In response to the environmental site audit findings,
the Contractor have rectified most of the observations as identified in
environmental site inspections undertaken during the reporting period. Details
of site audit findings and the corrective actions during the reporting period
are presented in Appendix F.
3.1.2 Summary of environmental site inspections of landscape works for the
Contract works area are presented in Appendix F. The landscape work for the
Contract was conducted during the reporting period. The implementation of
mitigation measures for landscape and visual resources recommended in the EIA
Report were monitored during the reporting period. Landscape and visual
mitigation measures in accordance with the EP, EIA and EM&A Manual were
implemented by the Contractor.
3.1.3
A summary of the Implementation Schedule of
Environmental Mitigation Measures (EMIS) is presented in Appendix E. Most of the necessary mitigation measures were
implemented properly.
3.1.4
Regular marine travel route for
marine vessels were implemented properly in accordance to the submitted plan
and relevant records were kept properly.
3.1.5
Dolphin Watching Plan was
implemented during the reporting period. No dolphins inside the silt curtain were observed. The relevant
records were kept properly.
3.2.1
The monitoring results for 1-hour TSP and 24-hour TSP
are summarized in Tables 3.1 and 3.2 respectively.
Detailed impact air quality monitoring results and relevant graphical
plots are presented in Appendix G.
Table 3.1 Summary
of 1-hour TSP Monitoring Results Obtained During the Reporting Period
Reporting Period
|
Monitoring
Station
|
Average (mg/m3)
|
Range (mg/m3)
|
Action Level (mg/m3)
|
Limit Level (mg/m3)
|
Jun 2020
|
AMS5
|
14
|
1 - 56
|
352
|
500
|
AMS6
|
12
|
3 - 38
|
360
|
Jul 2020
|
AMS5
|
11
|
2 - 52
|
352
|
AMS6
|
13
|
4 - 42
|
360
|
Aug 2020
|
AMS5
|
29
|
15 - 75
|
352
|
AMS6
|
22
|
11 - 30
|
360
|
Table 3.2 Summary
of 24-hour TSP Monitoring Results Obtained During the Reporting Period
Reporting Period
|
Monitoring
Station
|
Average (mg/m3)
|
Range (mg/m3)
|
Action Level (mg/m3)
|
Limit Level (mg/m3)
|
Jun 2020
|
AMS5
|
18
|
11
- 23
|
164
|
260
|
AMS6
|
18
|
14
- 24
|
173
|
Jul 2020
|
AMS5
|
24
|
17
- 42
|
164
|
AMS6
|
19
|
12
- 26
|
173
|
Aug 2020
|
AMS5
|
31
|
14 - 46
|
164
|
AMS6
|
26
|
13 - 49
|
173
|
3.2.2
No Action and Limit Level exceedances of 1-hr TSP and 24-hr
TSP were recorded at AMS5 and AMS6 during the reporting period.
3.3
Noise
Monitoring Results
3.3.1
The monitoring results for construction noise are
summarized in Table 3.3 and the monitoring
results and relevant graphical plots for this reporting period are provided in Appendix H.
Table 3.3 Summary of Construction Noise Monitoring
Results Obtained During the Reporting Period
Reporting period
|
Monitoring Station
|
Average Leq (30 mins), dB(A)*
|
Range of Leq (30 mins), dB(A)*
|
Action Level
|
Limit Level Leq (30 mins), dB(A)
|
Jun 2020
|
NMS5
|
58
|
54 - 59
|
When one documented complaint is received
|
75
|
Jul 2020
|
62
|
57 - 73
|
Aug 2020
|
65
|
59 - 69
|
3.3.2 No Action/Limit Level exceedances for noise were recorded during
daytime on normal weekdays of the reporting period.
3.3.3
Other noise sources during the noise monitoring
included insect noise, aircraft/helicopter noise, construction activities by
other parties and human activities nearby.
3.4.1 The water quality monitoring programme was temporarily suspended during the reporting
period since no marine works were scheduled or conducted. Therefore, no water
quality monitoring was conducted and no water monitoring results are presented
during the reporting period.
3.5
Dolphin
Monitoring Results
3.5.1
The dolphin monitoring programme
was temporarily suspended during the reporting period since no marine works
were scheduled or conducted. Therefore, no quarterly analysis of dolphin
monitoring results and exceedances from June 2020
to August 2020 are presented.
3.6
Mudflat
Monitoring Results
Sedimentation Rate
Monitoring
3.6.1 The baseline sedimentation rate monitoring was in September 2012 and
impact sedimentation rate monitoring was undertaken on 5 June 2020. The mudflat
surface levels at the four established monitoring stations and the
corresponding XYZ HK1980 GRID coordinates are presented in Table 3.9 and Table 3.10.
Table 3.9 Measured
Mudflat Surface Level Results
|
Baseline Monitoring
(September 2012)
|
Impact Monitoring
(June
2020)
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
810291.160
|
816678.727
|
0.950
|
810291.177
|
816678.710
|
1.153
|
S2
|
810958.272
|
815831.531
|
0.864
|
810958.270
|
815831.535
|
0.957
|
S3
|
810716.585
|
815953.308
|
1.341
|
810716.586
|
815953.308
|
1.395
|
S4
|
811221.433
|
816151.381
|
0.931
|
811221.427
|
816151.391
|
1.087
|
Table 3.10 Comparison
of Measurement
|
Comparison of measurement
|
Remarks and
Recommendation
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
0.017
|
-0.017
|
0.203
|
Level continuously
increased
|
S2
|
-0.002
|
0.004
|
0.093
|
Level continuously increased
|
S3
|
0.001
|
0.000
|
0.054
|
Level continuously increased
|
S4
|
-0.006
|
0.010
|
0.156
|
Level continuously increased
|
3.6.2
This measurement result was generally and relatively higher than the
baseline measurement at S1, S2, S3 and S4. The mudflat level is continuously
increased.
Water Quality
Monitoring
3.6.3
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.
3.6.4 Impact water quality
monitoring in San Tau (monitoring station SR3(N)) was conducted in June 2020 as
part of mudflat monitoring. The monitoring parameters included dissolved oxygen
(DO), turbidity and suspended solids (SS).
3.6.5 The
impact monitoring result for SR3(N) were extracted and summarised in Table 3.11:
Table 3.11 Impact
Water Quality Monitoring Results (Depth Average)
Date
|
Mid Ebb Tide
|
Mid Flood Tide
|
DO (mg/L)
|
Turbidity (NTU)
|
SS (mg/L)
|
DO (mg/L)
|
Turbidity (NTU)
|
SS (mg/L)
|
01-Jun-2020
|
6.5
|
5.2
|
4.8
|
6.4
|
4.7
|
4.4
|
03-Jun-2020
|
6.8
|
8.0
|
9.2
|
6.5
|
9.6
|
8.3
|
05-Jun-2020
|
6.3
|
14.5
|
17.9
|
6.3
|
11.2
|
14.4
|
08-Jun-2020
|
6.3
|
5.9
|
7.4
|
6.4
|
5.9
|
7.7
|
10-Jun-2020
|
6.4
|
5.7
|
6.3
|
6.5
|
6.3
|
6.6
|
12-Jun-2020
|
6.6
|
7.1
|
6.0
|
6.7
|
6.1
|
5.9
|
15-Jun-2020
|
11.0
|
5.5
|
11.1
|
11.4
|
5.6
|
11.2
|
17-Jun-2020
|
9.6
|
6.5
|
10.9
|
10.1
|
6.8
|
10.3
|
19-Jun-2020
|
7.7
|
10.2
|
10.7
|
8.0
|
10.2
|
9.5
|
22-Jun-2020
|
7.8
|
5.7
|
7.1
|
7.6
|
5.4
|
7.3
|
24-Jun-2020
|
7.2
|
4.8
|
7.5
|
7.1
|
5.2
|
7.2
|
26-Jun-2020
|
7.4
|
7.4
|
5.6
|
7.4
|
7.5
|
6.5
|
29-Jun-2020
|
8.8
|
3.4
|
5.5
|
9.2
|
3.4
|
5.8
|
Average
|
7.6
|
6.9
|
8.5
|
7.7
|
6.8
|
8.1
|
Mudflat Ecology
Monitoring
Sampling Zone
3.6.6 In order to collect baseline information of mudflats in the study
site, the study site was divided into three sampling zones (labeled as TC1,
TC2, TC3) in Tung Chung Bay and one zone in San Tau (labeled as ST) (Figure 2.1 of Appendix O). 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 O). Survey of horseshoe crabs,
seagrass beds and intertidal communities were conducted in every sampling zone.
The present survey was conducted in June 2020 (totally 4 sampling days on 17th, 19th, 22nd and 23rd
June 2020).
3.6.7 Since the field survey of June 2016, increasing number of trashes
and even big trashes (Figure 2.3 of Appendix
O) were found in every
sampling zone. It raised a concern about the solid waste dumping and
current-driven waste issues in Tung Chung Wan. Respective measures (e.g. manual
clean-up) should be implemented by responsible governmental agency units.
Horseshoe Crabs
3.6.8 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 17th (for TC1), 19th (for TC2), 22nd (for TC3) and 23rd (for ST) June 2020,
which were hot and wet days.
3.6.9 In June 2017, a big horseshoe crab was tangled by a trash gill net
in ST mudflat (Figure 2.3 of Appendix
O). It was released to sea
once after photo recording. The horseshoe crab of such size should be
inhabiting sub-tidal environment while it forages on intertidal shore
occasionally during high tide period. If it is tangled by the trash net for few
days, it may die due to starvation or overheat during low tide period. These
trash gill nets are definitely ¡¥fatal trap¡¦ for the horseshoe crabs and other
marine life. Manual clean-up should be implemented as soon as possible by
responsible governmental agency units.
Seagrass Beds
3.6.10 Active search method was adopted for
seagrass bed monitoring by two experienced surveyors in every sampling zone.
During the search period, any accessible and potential area would be
investigated for any seagrass beds within 2-3 hours of low tide period. Once
seagrass bed was found, the species, estimated area, estimated coverage
percentage and respective GPS coordinates were recorded. The seagrass beds
surveys were conducted on 17th (for TC1), 19th (for TC2), 22nd (for TC3) and 23rd
(for ST) June 2020, which were hot and wet days.
Intertidal Soft Shore Communities
3.6.11
The intertidal soft shore community surveys were conducted in low tide
period on 17th (for TC1), 19th (for TC2), 22nd (for TC3) and 23rd (for ST) June 2020. In every sampling zone, three 100m horizontal transect lines were laid
at high tidal level (H: 2.0m above C.D.), mid tidal level (M: 1.5m above C.D.)
and low tidal level (L: 1.0m above C.D.). Along every horizontal transect line;
ten random quadrats (0.5 m x 0.5m) were placed.
3.6.12 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.
3.6.13 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.
3.6.14 The
taxonomic classification was conducted in accordance to the following
references: Polychaetes: Fauchald
(1977), Yang and Sun (1988); Arthropods: Dai and Yang (1991), Dong (1991);
Mollusks: Chan and Caley (2003), Qi (2004), AFCD (2018).
Data Analysis
3.6.15
Data collected from direct search 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.
Mudflat Ecology Monitoring Results and Conclusion
Horseshoe Crabs
3.6.16 In
total of 32 and 25 individuals of Carcinoscorpius rotundicauda and Tachypleus
tridentatus were found in present survey. The
recorded individuals were mainly distributed along the shoreline in ST. All of
them were observed on similar substratum (fine sand or soft mud, slightly
submerged). Photo records of the observed horseshoe crab are shown in Figure 3.1 of Appendix O and
the present survey result regarding horseshoe crab are presented in Table 3.1 of Appendix O. The complete survey records are presented
in Annex II of Appendix O.
3.6.17 Carcinoscorpius rotundicauda, were only found in ST (32 ind.) with
average body size 39.05 mm (prosomal width ranged 27.34 mm ¡V 53.27 mm). The search records in ST was moderate (ST: 5.33 ind. hr-1.
Person-1). No Carcinoscorpius rotundicauda was
found in TC1, TC2 and TC3 in present survey.
3.6.18
Tachypleus tridentatus,
25 individuals with average body size 42.67 mm
(prosomal width ranged 28.53 ¡V 55.46 mm) were found in ST. The search record in
ST was moderate (4.17 ind. hr-1. Person-1). No Tachypleus tridentatus was
found in TC1, TC2 and TC3 in present survey.
3.6.19
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 O). In December 2017 and June 2018, one mating pair was of Carcinoscorpius rotundicauda
was found in TC3 (December 2017: male 127.80 mm, female 144.61 mm; June 2018:
male 139 mm, female 149 mm). In June 2019, 2 mating
pairs of Tachypleus tridentatus with
large body sizes (male 150mm and Female 200mm; Male 180mm and Female 220mm) was
found in TC3. Another mating pair of Tachypleus tridentatus was found in ST (male 140mm and Female
180mm). In March 2020, a pair of Tachypleus tridentatus with large body sizes (male 123mm and
Female 137mm was recorded in TC1. Figure
3.2 of Appendix O shows the photographic records of
mating pairs found. The recorded mating pairs were found nearly burrowing in
soft mud at low tidal level (0.5-1.0 m above C.D.). The smaller male was
holding the opisthosoma (abdomen carapace) of larger female from behind. The
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 O). No mating pair was found in June 2020
(present survey).
3.6.20
No large individuals (prosomal
width >100mm) of Carcinoscorpius rotundicauda and Tachypleus tridentatus was
recorded in June 2020 (present survey). In
December 2018, one large individual of Carcinoscorpius
rotundicauda was found in TC3 (prosomal width
148.9 mm). In March 2019, 3 large individuals (prosomal width ranged 220 ¡V
310mm) of Carcinoscorpius rotundicauda were observed in TC2. In June 2019, there
were 3 and 7 large individuals of Tachypleus
tridentatus were recorded in ST (prosomal width
ranged 140
¡V 180mm) and TC3 (prosomal width ranged 150 ¡V
220mm), respectively. In March 2020, a mating pair of Tachypleus tridentatus was
recorded in TC1 with prosomal width 123 mm and 137mm. Based on their sizes, it indicated that individuals of prosomal width
larger than 100 mm would progress its nursery stage from intertidal habitat to
sub-tidal habitat of Tung Chung Wan. The photo records
of the large horseshoe crab are shown in Figure 3.4 of Appendix O. 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.
3.6.21
No marked individual of horseshoe crab was recorded in June 2020 (present survey). Some marked individuals
were found in the previous surveys of September 2013, March 2014 and September
2014. All of them were released through a conservation programme
in charged by Prof. Paul Shin (Department of Biology and Chemistry, The City
University of Hong Kong (CityU)). It was a
re-introduction trial of artificial bred horseshoe crab juvenile at selected
sites. So that the horseshoe crabs population might be restored in the natural
habitat. Through a personal conversation with Prof. Shin, about 100 individuals
were released in the sampling zone ST on 20 June 2013. All of them were marked
with color tape and internal chip detected by specific chip sensor. There
should be second round of release between June and September 2014 since new
marked individuals were found in the survey of September 2014.
3.6.22 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
3.6.23 Figure 3.5 and 3.6 of Appendix
O 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.
3.6.24 To consider the entire monitoring
period for TC3 and ST, medium to high search records (i.e. number of
individuals) of both species (Carcinoscorpius rotundicauda and Tachypleus tridentatus)
were usually found in wet season (June and September). The search record of ST
was higher from September 2012 to June 2014 while it was replaced by TC3 from
September 2014 to June 2015. The search records were similar between two
sampling zones from September 2015 to June 2016. In September 2016, the search
record of Carcinoscorpius rotundicauda
in ST was much higher than TC3. From March to June 2017, the search records of
both species were similar again between two sampling zones. It showed a natural
variation of horseshoe crab population in these two zones due to weather
condition and tidal effect. No obvious difference of horseshoe crab population
was noted between TC3 and ST. In September 2017, the search records of both
horseshoe crab species decreased except the Carcinoscorpius rotundicauda
in TC3. The survey results were different from previous findings that there
were usually higher search records in September. One possible reason was that
the serial cyclone hit decreased horseshoe crab activity (totally 4 cyclone
records between June and September 2017, to be discussed in 'Seagrass survey'
section). From December 2017 to September 2018, the search records of both
species increased again to low-moderate level in ST. From December 2018 to March 2020, the search records of Carcinoscorpius rotundicauda change from very low to low while the
change of Tachypleus tridentatus was similar during this period. In June 2020
(present survey), the search records of both species, Carcinoscorpius rotundicauda and
Tachypleus tridentatus,
were increased to moderate level in ST. However, none of them were recorded
in TC3. Relatively
higher population fluctuation of Carcinoscorpius rotundicauda was observed in TC3.
3.6.25 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.
3.6.26 About the body size, larger
individuals of Carcinoscorpius rotundicauda
were usually found in ST and TC1 relative to that in TC3 from September 2012 to
June 2017. But the body size was higher in TC3 and ST followed by TC1 from
September 2017 to June 2020 (present survey). For Tachypleus tridentatus, larger individuals were
usually found in ST and TC3 followed by TC1 throughout the monitoring period. In
June 2019, all found horseshoe crabs were large individuals and mating pairs.
It is believed that the size of horseshoe crabs would be decrease and gradually
rise afterward due to the stable growth of juveniles after the spawning season.
3.6.27 In general, it was obvious that
the shoreline along TC3 and ST (western shore of Tung Chung Wan) was an
important nursery ground for horseshoe crab especially newly hatched
individuals due to larger area of suitable substratum (fine sand or soft mud)
and less human disturbance (far from urban district). Relatively, other
sampling zones were not a suitable nursery ground especially TC2. Possible
factors were less area of suitable substratum (especially TC1) and higher human
disturbance (TC1 and TC2: close to urban district and easily accessible). In
TC2, large daily salinity fluctuation was a possible factor either since it was
flushed by two rivers under tidal inundation. The individuals inhabiting TC1
and TC2 were confined in small foraging area due to limited area of suitable
substratum. Although there were mating pairs of seldomly found in TC1 and TC2,
the hatching rate and survival rate of newly hatched individuals were believed
very low.
Seasonal variation of horseshoe crab population
3.6.28 Throughout
the monitoring period, the search records of horseshoe crabs were fluctuated
and at moderate ¡V very low level in June (Figures
3.5 and 3.6 of Appendix O). Low
¡V Very low search record was found in June 2013, totally 82 individuals of Tachypleus tridentatus
and 0 ind. of Carcinoscorpius rotundicauda were
found in TC1, TC3 and ST. Compare with the search record of June 2013, the
numbers of Tachypleus tridentatus
were gradually decreased in June 2014 and 2015 (55 ind. in 2014 and 18 ind. in
2015); the number of Carcinoscorpius
rotundicauda raise to 88 and 66 individuals. in
June 2014 and 2015 respectively. In June 2016, the search record increased
about 3 times compare with June 2015. In total, 182 individuals of Carcinoscorpius rotundicauda
and 47 individuals. of Tachypleus tridentatus
were noted, respectively. Then, the search record was similar to June 2016. The
number of recorded Carcinoscorpius rotundicauda (133
ind.) slightly dropped in June 2017. However, that of Tachypleus tridentatus rapidly increased (125
ind.). In June 2018, the search record was low to moderate while the numbers of
Tachypleus tridentatus
dropped sharply (39 ind.). In June 2019, 10 individuals of Tachypleus tridentatus were
observed in TC3 and ST. All of them, however, were large
individuals (prosomal width >100mm), their records are excluded from the
data analysis to avoid mixing up with the juvenile population living on
intertidal habitat. Until June 2020 (present survey), the number of Carcinoscorpius rotundicauda
and Tachypleus tridentatus
gradually increased to 32 ind. and 25 ind., respectively. Throughout the
monitoring period, similar distribution of horseshoe crabs population were
found in June. Most of the horseshoe crabs were found in TC3 and ST.
3.6.29 The search record of horseshoe crab declined
obviously in all sampling zones during dry season especially December (Figures
3.5 and 3.6 of Appendix O) throughout the monitoring period. Very low
¡V low search record was found in December from 2012 to 2015 (0-4 ind. of Carcinoscorpius rotundicauda
and 0-12 ind. of Tachypleus tridentatus). The horseshoe crabs were inactive and
burrowed in the sediments during cold weather (<15 ºC). Similar results of
low search record in dry season were reported in a previous territory-wide
survey of horseshoe crab. For example, the search records in Tung Chung Wan
were 0.17 ind. hr-1person-1 and 0.00 ind. hr-1
person-1 in wet season and dry season respectively (details see Li,
2008). Compare with the search record of December from 2012 to 2015, which of
December 2016 were much higher relatively. There were totally 70 individuals of
Carcinoscorpius rotundicauda
and 24 individuals of Tachypleus tridentatus in TC3 and ST. Since the survey was carried
in earlier December with warm and sunny weather (~22 ºC during dawn according
to Hong Kong Observatory database, Chek Lap Kok station on 5 December 2016), the horseshoe crab was
more active (i.e. move onto intertidal shore during high tide for foraging and
breeding) and easier to be found. In contrast, there was no search record in
TC1 and TC2 because the survey was conducted in mid-December with colder and
cloudy weather (~20 ºC
during dawn on 19 December). The horseshoe crab activity would decrease
gradually with the colder climate. In December of 2017 and 2018, very low
search records were found again as mentioned above.
3.6.30 From September 2012 to December
2013, Carcinoscorpius rotundicauda was
less common species relative to Tachypleus tridentatus. Only 4 individuals were ever recorded in
ST in December 2012. This species had ever been believed of very low density in
ST hence the encounter rate was very low. In March 2014, it was found in all
sampling zones with higher abundance in ST. Based on its average size (mean
prosomal width 39.28 mm - 49.81 mm), it indicated that breeding and spawning of
this species had occurred about 3 years ago along the coastline of Tung 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).
3.6.31 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. In June 2020
(present survey), 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 43mm.
3.6.32 Recently, Carcinoscorpius rotundicauda
was a more common horseshoe crab species in Tung Chung Wan. It was recorded in
the four sampling zones while the majority of population located in TC3 and ST.
Due to potential breeding last year, the number of Tachypleus tridentatus became increased TC3 and ST.
Since TC3 and ST were regarded as important nursery ground for both horseshoe
crab species, box plots of prosomal width of two horseshoe crab species were constructed
to investigate the changes of population in details.
Box plot of horseshoe crab populations in TC3
3.6.33 Figure
3.7 of Appendix O 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.
3.6.34 For Tachypleus tridentatus,
the major size ranged 20-50 mm while the number of individuals fluctuated from
September 2012 to June 2014. Then a slight but consistent growing trend was
observed from September 2014 to June 2015. The prosomal width increased from 25
¡V 35 mm to 35 ¡V
65 mm.
As mentioned, the large individuals might have reached a suitable size for
migrating from the nursery soft shore to subtidal habitat. It accounted for the
declined population in TC3. From March to September 2016, slight increasing
trend of major size was noticed again. From December 2016 to June 2017, similar
increasing trend of major size was noted with much higher number of
individuals. It reflected new round of spawning. In September 2017, the major
size decreased while the trend was different from previous two years. Such
decline might be the cause of serial cyclone hit between June and September
2017 (to be discussed in the 'Seagrass survey' section). From December 2017 to
September 2018, increasing trend was noted again. It indicated
a stable growth of individuals. From September 2018 to that of next year, the
average prosomal widths were decreased from 60mm to 36mm. It indicated new
rounds of spawning occurred during September to November 2018. In December
2019, an individual with larger body size (prosomal width 65mm) was found in
TC3 which reflected the stable growth of individuals. In
March 2020, the average prosomal width (middle line of the whole box) of Tachypleus tridentatus in
TC3 was 33.97 mm which is smaller than that in December 2019. It was in normal
fluctuation. In June 2020 (present survey), no horseshoe crab was recorded in
TC3. Across
the whole monitoring period, the larger juveniles (upper whisker) usually
reached 60
¡V 80 mm in prosomal width,
even 90 mm occasionally. The juveniles reaching this size might gradually
migrate to sub-tidal habitats.
Box plot of horseshoe crab populations in ST
3.6.35 Figure
3.8 of Appendix O 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.
3.6.36 For Tachypleus tridentatus, a consistent growing trend
was observed for the major population from December 2012 to December 2014
regardless of change of search record. The prosomal width increased from 15-30
mm to 60 ¡V 70 mm. As mentioned, the large juveniles might have reached a suitable size
for migrating from the nursery soft shore to subtidal habitat. From March to
September 2015, the size of major population decreased slightly to a prosomal
width 40 ¡V 60 mm. At the same time, the number of individuals decreased gradually.
It further indicated some of large juveniles might have migrated to sub-tidal
habitat, leaving the smaller individuals on shore. There was an overall growth
trend. In December 2015, two big individuals (prosomal width 89.27 mm and 98.89
mm) were recorded only while it could not represent the major population. In
March 2016, the number of individual was very few in ST that no box plot could
be produced. In June 2016, the prosomal width of major population ranged 50 ¡V 70 mm. But it dropped clearly to
30 ¡V 40 mm in
September 2016 followed by an increase to 40 ¡V 50 mm in December 2016, 40 ¡V 70 mm in March 2017 and 50 ¡V 60mm in June 2017. Based on
overall higher number of small individuals from June 2016 to September 2017, it
indicated another round of spawning. From September 2017 to June 2018, the
major size range increased slightly from 40 ¡V 50 mm to 45 ¡V 60 mm indicating a continuous growth.
In September 2018, decrease of major size was noted again that might reflect
new round of spawning. Throughout the monitoring period, the larger juveniles
ranged 60¡V 80 mm in prosomal width. Juveniles reaching this size would gradually
migrate to sub-tidal habitats.
3.6.37 As a summary for horseshoe crab
populations in TC3 and ST, there were spawning of Carcinoscorpius rotundicauda
from 2014 to 2018 while the spawning time should be in spring. The population
size was consistent in these two sampling zones. For Tachypleus tridentatus, small individuals were
rarely found in both zones from 2014 to 2015. It was believed no occurrence of
successful spawning. The existing individuals (that recorded since 2012) grew
to a mature size and migrated to sub-tidal habitat. Hence the number of
individuals decreased gradually. From 2016 to 2018, new rounds of spawning were
recorded in ST while the population size increased to a moderate level.
3.6.38 In
March 2019 to June 2019, no
horseshoe crab juveniles (prosomal
width <100mm) were recorded in TC3 and ST. All recorded horseshoe crabs were large individuals (prosomal width
>100mm) or mating pairs which were all excluded from the data analysis. From September
2019 to June 2020 (present survey), the population size of both horseshoe crab
species in TC3 and ST gradually increased to moderate level while their body
sizes were mostly in small to medium range (~25 ¡V 50mm).
Impact of the HKLR
project
3.6.39 It was
the 31st 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
3.6.40 Only
seagrass species Halophila ovalis was found in present survey,
which was found in TC3 and ST. In ST,
there were two small sized and one
large sized of seagrass beds found at tidal
zone 1.5 ¡V 2.0 m above C.D nearby mangroves plantation. The larger strand had area ~1050 m2 in high vegetation
coverage (90 ¡V 100%). At close vicinity, two small sized (~2 and 27 m2) of Halophila ovalis
beds were observed
at tidal zone 1.5 ¡V 2.0m above
C.D. Both of them were in high vegetation coverage (90 ¡V 100%). In TC3, six
small patches of Halophila ovalis were found at tidal zone 1.5 ¡V 2.0m
above C.D. These seagrass patch had area 6 m2 ¡V 42.25m2.
They were in moderate to high vegetation coverage (50 ¡V 100%). Another seagrass
species Zostera japonica was not found
in present survey. Table 3.2 of Appendix O summarizes the results of
present seagrass beds survey and the photograph records of the seagrass are
shown on Figure 3.9 of Appendix O. The complete record throughout
the monitoring period is presented in Annex
III of Appendix O.
3.6.41 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 O). In general, Halophila ovalis was occasionally found
in TC3 in few, small to medium patches. But it was commonly found in ST in
medium to large seagrass bed. Moreover, it had sometimes grown extensively and
had covered significant mudflat area at 0.5
¡V 2.0 m above C.D. between TC3 and ST. Another seagrass
species Zostera japonica was found in ST only. It was
relatively lower in vegetation area and co-existed with Halophila ovalis nearby the mangrove strand at 2.0 m above C.D.
3.6.42 According to the previous results, majority
of seagrass bed was confined in ST, the temporal change of both seagrass
species were investigated in details:
Temporal variation of seagrass beds
3.6.43 Figure 3.11 of Appendix
O
shows the changes of estimated total area of
seagrass beds in ST along the sampling months. For Zostera japonica, it was not recorded in the 1st
and 2nd surveys of monitoring programme.
Seasonal recruitment of few, small patches (total seagrass area: 10 m2) was
found in Mach 2013 that grew within the large patch of seagrass Halophila
ovalis. Then, the patch size increased and merged gradually with the warmer
climate from March to June 2013 (15 m2). However, the patch size
decreased and remained similar from September 2013 (4 m2) to March
2014 (3 m2). In June 2014, the patch size increased obviously again
(41 m2) with warmer climate followed by a decrease between September
2014 (2 m2) and December 2014 (5 m2).
From March to June 2015, the patch size increased sharply again (90 m2).
It might be due to the disappearance of the originally dominant seagrass Halophila
ovalis resulting in less competition for substratum and nutrients. From
September 2015 to June 2016, it was found coexisting with seagrass Halophila
ovalis with steady increasing patch size (from 44 m2 to 115 m2)
and variable coverage. In September 2016, the patch size decreased again to (38
m2) followed by an increase to a horizontal strand (105.4 m2)
in June 2017. And it did no longer co-exist with Halophila ovalis.
Between September 2014 and June 2017, an increasing trend was noticed from
September to June of next year followed by a rapid decline in September of next
year. It was possibly the causes of heat stress, typhoon and stronger grazing
pressure during wet season. However, such increasing trend was not found from
September 2017 to June 2020 (present survey) while no patch of Zostera japonica was found.
3.6.44 For Halophila ovalis, it was recorded
as 3 ¡V 4 medium
to large patches (area 18.9 - 251.7 m2;
vegetation coverage 50 - 80%) beside the mangrove
vegetation at tidal level 2 m above C.D. in September 2012. The total seagrass
bed area grew steadily from 332.3 m2 in September 2012 to 727.4 m2
in December 2013. Flowers were observed in the largest patch during its
flowering period. In March 2014, 31 small to medium patches were newly recorded
(variable area 1 ¡V 72
m2 per patch, vegetation coverage 40-80% per patch) in lower tidal
zone between 1.0 and 1.5 m above C.D. The total seagrass area increased further
to 1350 m2. In June 2014, these small and medium patches grew and
extended to each other. These patches were no longer distinguishable and were
covering a significant mudflat area of ST. It was generally grouped into 4
large patches (1116 - 2443 m2) of seagrass beds characterized of
patchy distribution, variable vegetable coverage (40 - 80%) and smaller leaves.
The total seagrass bed area increased sharply to 7629 m2. In
September 2014, the total seagrass area declined sharply to 1111m2.
There were only 3 - 4 small to large patches (6 - 253 m2) at high
tidal level and 1 large patch at low tidal level (786 m2). Typhoon
or strong water current was a possible cause (Fong, 1998). In September 2014,
there were two tropical cyclone records in Hong Kong (7th-8th September:
no cyclone name, maximum signal number 1; 14th - 17th September:
Kalmaegi, maximum signal number 8SE) before the
seagrass survey dated 21st September 2014. The strong water current
caused by the cyclone, Kalmaegi especially, might
have given damage to the seagrass beds. In addition, natural heat stress and
grazing force were other possible causes reducing seagrass beds area. Besides,
very small patches of Halophila ovalis could be found in other mud flat
area in addition to the recorded patches. But it was hardly distinguished due
to very low coverage (10 - 20%) and small leaves.
3.6.45 In
December 2014, all the seagrass patches of Halophila
ovalis disappeared in ST. Figure
3.12 of Appendix
O 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
3.6.46 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.
3.6.47 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).
3.6.48
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.
3.6.49
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
3.6.50 Figure 3.12 of Appendix
O 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
3.6.51 In September 2017, the whole seagrass bed of Halophila ovalis disappeared again along the shore of TC3 and ST (Figure 3.12 of Appendix O). Similar to the first disappearance of seagrass bed occurred
between September and December 2014, strong water current (e.g. cyclone) or
deteriorated water qualities (e.g. high turbidity) was the possible cause.
3.6.52 Between the survey periods of June and September 2017, there were
four tropical cyclone records in Hong Kong (Merbok in
12 - 13th, June; Roke in 23rd,
Jul.; Hato in 22 - 23rd, Aug.; Pakhar in 26-27th, Aug.) (Online database of
Hong Kong Observatory). All of them reaches signal 8 or above, especially Hato with highest signal 10.
3.6.53 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.
3.6.54 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 O). It was
different from the previous round (March 2015 - June 2017). Until June 2018,
the new seagrass patches with small-medium size were found at the usual
location (seaward side of mangrove plantation at 2.0 m C.D.) again, indicating
the recolonization. However, the seagrass bed area decreased sharply to 22.5 m2
in September 2018. Again, it was believed that the decrease was due to the hit
of the super cyclone in September 2018 (Mangkhuton 16th
September, highest signal 10). From December 2018 to June 2019, the seagrass
bed area increased from 404 m2 to 1229 m2 while the
vegetation coverage is also increased. (December 2018: 5 ¡V 85%; March 2019: 50
¡V 100% and June 2019: 60 ¡V 100%). Relatively, the whole recolonization process
would occur slower than the previous round (more than 2 years). From September 2019 to June 2020
(present survey), the seagrass bed area slightly decreased from 1200 m2 to
1079 m2 which were in normal fluctuation.
Impact of the HKLR project
3.6.55 It was the 31st survey of the EM&A programme during construction period. Throughout the
monitoring period, the disappearance of seagrass beds was believed the cause of
cyclone hits rather than impact of HKLR project. The seagrass bed was
recolonizing since there had been a gradual increase in the size
and number from December 2018 to June 2019 after the hit of the super cyclone
in September 2018. The
seagrass bed area slightly decreased from September 2019 to June 2020 (present
survey) which were in normal fluctuation.
Intertidal Soft
Shore Communities
Substratum
3.6.56 Table 3.3 and Figure 3.13 of Appendix O show the substratum types along
the horizontal transect at every tidal level in all sampling zones. The
relative distribution of substratum types was estimated by categorizing the
substratum types (Gravels & Boulders / Sands / Soft mud) of the ten random
quadrats along the horizontal transect. The distribution of substratum types
varied among tidal levels and sampling zones:
¡P
In TC1, high percentages of ¡¥Gravels and
Boulders¡¦ (H: 70%; M:
80%) were recorded at
high and mid tidal levels. Relatively higher percentages of ¡¥Gravels and
Boulders¡¦ (60%) and ¡¥Soft mud¡¦ (30%) were recorded at low tidal level.
¡P
In TC2, high percentages of ¡¥Gravels and Boulders¡¦ (H: 70%; M: 50%) were
recorded at high and mid tidal levels. Relatively
higher percentages of ¡¥Soft mud¡¦ (50%) and ¡¥Gravels and Boulders¡¦ (40%) were
recorded at low tidal level.
¡P
In TC3, higher percentage of ¡¥Gravels and Boulders¡¦ (80%) was recorded at high tidal level. At
mid and low tidal level, higher percentage of ¡¥Gravels and Boulders¡¦ (70%) were
recorded.
¡P
In ST, ¡¥Gravels and
Boulders¡¦ was the main substratum type (H: 90%; M: 70%) at high tidal level and mid tidal level. At low tidal level,
¡¥Gravels and Boulders¡¦ was the main substratum type (60%) following by
¡¥Sand¡¥(20%) and ¡¥Soft Mud¡¥(20%).).
3.6.57 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
3.6.58 Table 3.4 of Appendix O lists the total abundance, density and number of taxon of every phylum in
this
survey. A total of 11356 individuals were recorded.
Mollusca was the most abundant phylum (total abundance 11356 ind, density 379 ind. m-2, relative abundance
95.1%). The second was Arthropoda (394 ind., 13 ind. m-2, 3.3%)
which followed by Sipuncula (118 ind., 3.9 ind. m-2, 1.0%).
Relatively other phyla were very low in abundances (density <2 ind. m-2,
relative abundance £0.4%). Moreover, the most diverse phylum was Mollusca (33 taxa) followed by Arthropoda (6 taxa)
and Annelida (3 taxa). There were
2 taxa recorded for Sipuncula and 1 taxon for other phyla.
3.6.59 The taxonomic resolution and complete list of recorded fauna are
shown in Annexes IV and V of Appendix O respectively. As reported in June 2018, taxonomic revision of three
potamidid snail species was conducted according to the latest identification
key published by Agriculture, Fisheries and Conservation Department (details
see AFCD, 2018), the species names of following gastropod species were revised:
¡P
Cerithidea cingulata was
revised as Pirenella asiatica
¡P
Cerithidea djadjariensis was
revised as Pirenella incisa
¡P
Cerithidea rhizophorarum was revised
as Cerithidea moerchii
Moreover, taxonomic revision was
conducted on another snail species while the specie name was revised:
¡P
Batillaria bornii was revised as Clypeomorus bifasciata
3.6.60 Table 3.5 of Appendix O shows the number of individual, relative abundance and density of each phylum in every sampling zone.
The total abundance (2499 ¡V 3238 ind.)
varied among the four sampling zones while the phyla
distributions were
similar. In general, Mollusca was the most dominant phylum (no. of individuals: 2354
¡V 3117 ind.; relative abundance 93.5 ¡V 96.3%; density 314 ¡V 416 ind. m-2).
Other phyla were much lower in number of individuals. Arthropoda (63 ¡V 161
ind.; 2.0 ¡V 5.2%; 8 ¡V 21 ind. m-2), Sipuncula (16 ¡V 37 ind.; 0.5 ¡V 1.4%; 2
¡V 5 ind. m-2) were common phyla relatively. Other phyla were very low in abundance
in all sampling zones.
Dominant species in
every sampling zone
3.6.61
Table 3.6 of Appendix O lists the abundant species in
every sampling zone. In the present survey, most of the
listed abundant species were of low to moderate densities (42 ¡V 100 ind. m-2).
Few listed species of high or very high density (>100 ind. m-2)
were regarded as dominant species. Other listed species of lower density
(<42 ind. m-2) were regarded as common species.
3.6.62
In TC1, the substratum was mainly ¡¥Gravels
and Boulders¡¦ at high and mid tidal
levels. At high tidal level, the rock oyster Saccostrea cucullata (mean density 143 ind. m-2;
relative abundance 34%) was of dominant species found at high density while the
gastropod Monodonta labio
(80 ind. m-2; relative abundance 19%) found at low to moderate densities. At mid tidal level, the rock oyster Saccostrea cucullata (128 ind. m-2,
31%) was of dominant species with high density. Meanwhile, the gastropod Monodonta labio (92 ind. m-2, 22%) found at low to moderate density.
At low tidal level (main substratum
types ¡¥Gravels and Boulders¡¦), the rock oyster Saccostrea cucullata (107 ind. m-2, 26%) and the
gastropod Monodonta labio
(119 ind. m-2, 29%) were dominant at high density.
3.6.63
In TC2, the substratum types were mainly '
Gravels and Boulders' at high tidal level. The gastropod Batillaria
multiformis (87 ind. m-2, 24%), the
rock oyster Saccostrea cucullata (75 ind. m-2,
21%), and the gastropod Monodonta labio (47 ind. m-2, 13%) were at low -
moderate density. At mid tidal level (major substratum type ¡¥Gravels and Boulders¡¦), rock oyster Saccostrea
cucullata (94 ind. m-2, 25%), the
gastropods Batillaria multiformis
(84 ind. m-2, 22%) and Monodonta
labio (57 ind. m-2, 15%) were at low ¡V
moderate density level. Substratum types ¡¥Gravels and Boulders¡¦ was mainly
distributed at low tidal level, rock oyster Saccostrea cucullata
(170 ind. m-2, 34%) and the gastropod Monodonta
labio (113 ind. m-2, 23%) were
dominant at high density.
3.6.64 In TC3 the substratum type was mainly ¡¥Gravels and Boulders¡¦ at high tidal level. The rock oyster Saccostrea cucullata (113 ind. m-2, 31%) was of
dominant species at high density. At mid tidal level, ¡¥Gravels and Boulders¡¦
was the mainly substratum type. The rock oyster Saccostrea cucullata (98 ind. m-2, 29%) and the
gastropod Batillaria multiformis
(52 ind. m-2, 16%) were at low ¡V moderate density level.
Meanwhile, the gastropod Monodonta labio (40 ind. m-2, 12%) was of common
species at low densities. At low tidal level, the major substratum type was
¡¥Gravels and Boulders¡¦. There was
dominated by rock oyster Saccostrea cucullata (130
ind. m-2, 343%) at high density.
3.6.65 In ST, the
major substratum type was ¡¥Gravels and Boulders¡¦ at high tidal level. At high
tidal level, the rock oyster Saccostrea cucullata (133
ind. m-2, 27%) was abundant at high densities. The gastropods Batillaria multiformis (47
ind. m-2, 11%) and Monodonta labio (40 ind. m-2, 10%) were the common
species at low - moderate density. At mid tidal level, the main substratum type
was ¡¥Gravels and Boulders¡¦. The rock oyster Saccostrea cucullata
(127 ind. m-2, 33%) was the dominant species at high density,
and followed by the gastropod Monodonta labio (53
ind. m-2, 14%) at low to moderate density. At low tidal
level (major substratum: ¡¥Gravels and Boulders¡¦), the rock oyster Saccostrea
cucullata (146 ind. m-2, 29 %,
attached on boulders) was dominant at high density. The gastropod Monodonta labio (91
ind. m-2, 18%) was the species at low ¡V moderate density.
3.6.66 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 (2402 ind.), gastropods Monodonta labio (1159
ind.) and Batillaria multiformis
(454 ind.) were the most common species on gravel and boulders substratum.
Rock oyster Saccostrea cucullata (S: 676 ind.¡¦
M: 569 ind.) was the most common species on sandy and soft mud substrata.
Biodiversity and
abundance of soft shore communities
3.6.67 Table 3.7 of Appendix O 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.
3.6.68 Among the sampling zones, the mean species number was similar (10 ¡V
13 spp. 0.25 m-2) among the four sampling zones. The mean densities
of ST (432 ind. m-2) was higher than TC1 (416 ind. m-2)
followed by TC2 (412 ind. m-2) and TC3 (330 ind. m-2).
The higher densities of ST and TC1 are due to the relatively high number of
individuals in each quadrat. TC1 and ST were relatively higher in H¡¦ (2.10 and
2.00) and followed by TC2 (1.83) and TC3 (1.77). Comparing with TC2 (J: 0.76)
and ST (0.78), TC1 and TC3 (both 0.82) were higher in J which were due
to their higher species number and even taxa distribution.
3.6.69 In the present survey, no clear
trend of mean species number, mean density, H¡¦
and J observed among the tidal level.
3.6.70 Figures 3.14 to 3.17 of Appendix O show the temporal changes
of mean species number, mean density, H¡¦ and J at every tidal
level and in every sampling zone along the sampling months. In general, all the
biological parameters fluctuated seasonally throughout the monitoring period.
Lower mean species number and density were recorded in dry season (December)
but the mean H' and J fluctuated within a limited range.
3.6.71 From June to December 2017, there
were steady decreasing trends of mean species number and density in TC2, TC3
and ST regardless of tidal levels. It might be an unfavorable change reflecting
environmental stresses. The heat stress and serial cyclone hit were believed
the causes during the wet season of 2017. From March 2018 to June 2020 (present
survey), increases of mean species number and density were observed in all
sampling zones. It indicated the recovery of intertidal community.
Impact
of the HKLR project
3.6.72 It was the 31st survey
of the EM&A programme during the construction
period. Based on the results, impacts of the HKLR project were not detected on
intertidal soft shore community. Abnormal phenomena (e.g. rapid, consistent or
non-seasonal decline of fauna densities and species number) were not recorded.
3.7
Solid and
Liquid Waste Management Status
3.7.1
The Contractor registered with EPD as a Chemical Waste
Producer on 12 July 2012 for the Contract. Sufficient numbers of receptacles
were available for general refuse collection and sorting.
3.7.2
The summary of waste flow table is detailed in Appendix K.
3.7.3
The Contractor was reminded that chemical waste
containers should be properly treated and stored temporarily in designated
chemical waste storage area on site in accordance with the Code of Practice on
the Packaging, Labelling and Storage of Chemical Wastes.
3.8
Environmental
Licenses and Permits
3.8.1
The valid environmental licenses and permits during
the reporting period are summarized in Appendix L.
4
Environmental Complaint and
Non-compliance
4.1.1
The summaries of the environmental exceedances are presented as
follows:
Air Quality
4.1.2
No Action Level and Limit level
exceedances of 1-hr TSP and 24-hr TSP were recorded at AMS5 and AMS6 during the
reporting period.
Noise
4.1.3 No Action/Limit Level exceedances for noise were recorded during
daytime on normal weekdays of the reporting period.
Water Quality
4.1.4 The water quality monitoring programme was temporarily suspended during the reporting
period since no marine works were scheduled or conducted. Therefore, no water
quality monitoring was conducted and no water monitoring results or exceedances
are presented during the reporting period.
Dolphin
4.1.5 The
dolphin monitoring programme was temporarily
suspended during the reporting period since no marine works were scheduled or
conducted. Therefore, no quarterly analysis of dolphin monitoring results and
exceedances from June 2020 to August 2020 are
presented.
4.2.1 There
was no complaint received in relation to the environmental impacts during this
reporting period.
4.2.2 The
details of cumulative statistics of Environmental Complaints are provided in Appendix N.
4.2.3 No notification of summons and
prosecution was received during the reporting period. Statistics on notifications
of summons and successful prosecutions are summarized in Appendix M.
5
Comments, Recommendations and Conclusion
5.1.1
According to the environmental
site inspections undertaken during the reporting period, the following
recommendations were provided:
¡P The Contractor was reminded to apply water spraying
prior to, during and after the breaking activities so as to maintain the entire surface wet
at S7.
¡P Water sprinkling should be provided to minimize
dust generation.
¡P The Contractor was reminded to maintain the silt
curtains properly at Portion X.
¡P Protection measures shall be implemented to prevent
silt and soil into U-channel at N1.
¡P The Contractor was reminded to remove the stagnant
water inside the drip tray at S7.
¡P The Contractor was reminded to remove the stagnant
water in lifting eye of the concrete block at S7.
¡P The Contractor was reminded to remove the waste at
LCSD Depot.
¡P The Contractor was reminded to remove the waste
from S7.
¡P The Contractor was reminded to remove the waste
near the site entrance/exit of WA6.
¡P The Contractor was reminded to remove the concrete
waste on the ground at S16.
¡P The Contractor was reminded to provide drip tray
for the chemical containers at S7.
5.2.1
The impact monitoring programme for air
quality, noise, water quality and dolphin
ensured that any deterioration in environmental condition was readily detected
and timely actions taken to rectify any non-compliance. Assessment and analysis
of monitoring results collected demonstrated the environmental impacts of the
contract. With implementation of the recommended environmental mitigation
measures, the contract¡¦s environmental impacts were considered environmentally
acceptable. The weekly environmental site inspections and bi-weekly
environmental site inspection of landscape works ensured that all the
environmental mitigation measures recommended were effectively implemented.
5.2.2
The
recommended environmental mitigation measures, as included in the EM&A programme, effectively minimize the potential environmental
impacts from the contract. Also, the EM&A programme
effectively monitored the environmental impacts from the construction
activities and ensure the proper implementation of mitigation measures. No
particular recommendation was advised for the improvement of the programme.
5.3.1 The construction phase and EM&A programme
of the Contract commenced on 17 October 2012. This is the thirty-second Quarterly EM&A Report which summarizes the monitoring results and
audit findings of the EM&A programme during the
reporting period from 1 June 2020 to 31 August 2020.
Air Quality
5.3.2
No Action Level and Limit Level
exceedances of 1-hr TSP and 24-hr TSP were recorded at AMS5 and AMS6 during the
reporting period.
Noise
5.3.3
No Action/Limit Level exceedances for noise were recorded during daytime
on normal weekdays of the reporting period.
Water Quality
5.3.4
The
water quality monitoring programme was temporarily suspended during the
reporting period since no marine works were scheduled or conducted. Therefore,
no water quality monitoring was conducted and no water monitoring results or
exceedances are presented during the reporting period.
Dolphin
5.3.5 The dolphin
monitoring programme was temporarily suspended during
the reporting period since no marine works were scheduled or conducted.
Therefore, no quarterly analysis of dolphin monitoring results and exceedances
from June 2020 to August 2020 are presented.
Mudflat - Sedimentation Rate
5.3.6
This measurement result was generally and relatively higher than the
baseline measurement at S1, S2, S3 and S4. The mudflat level is continuously
increased.
Mudflat - Ecology
5.3.7 The June 2020 survey results
indicate that the impacts of the HKLR project were not detected on intertidal
soft shore community. 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. 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 since there
had been a gradual increase in the size and number from December 2018 to June
2019 after the hit of the super cyclone in September 2018. The
seagrass bed area slightly decreased in September 2019 and June 2020 (present
survey) which was in normal fluctuation.
Environmental Site Inspection and Audit
5.3.8 Environmental site inspection was carried out
on 3, 10, 17 and 26 June 2020; 2, 8, 15, 22 and 31 July 2020; and 5, 12, 19 and 28 August 2020.
Recommendations on remedial actions were given to the Contractors for the
deficiencies identified during the site inspections.
5.3.9 There was no complaint received in relation to the environmental
impact during the reporting period.
5.3.10 No notification of summons and prosecution was received during the
reporting period.