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. 30 (December 2019 to February 2020)
6 April 2020
Revision 1
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 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 will be
providing environmental team services to the Contract.
This
is the thirtieth 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 December 2019 to 29
February 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
|
Dec 2019
|
Jan 2020
|
Feb 2020
|
Air
Quality
|
1-hr
TSP at AMS5 and AMS6
|
3, 9, 13, 18, 23 and 27
|
2, 8, 14, 20 and 24
|
5, 11, 17, 21 and 27
|
24-hr
TSP at AMS5
|
2, 6, 12, 17, 21, 27 and 31
|
6, 11, 17 and 23
|
4, 10, 14, 21 and 26
|
24-hr
TSP at AMS6
|
4, 10, 14, 20 and 26
|
Noise
|
3, 9, 18 and 23
|
3, 9, 14 and 21
|
5, 11, 17 and 27
|
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)
|
4,
5, 19, 20
|
-
|
-
|
Mudflat Monitoring (Sedimentation rate)
|
18
|
-
|
-
|
Site Inspection
|
3,
11, 17 and 27
|
2,
8, 15 and 22
|
7,
12, 19 and 28
|
Remarks: 1) Water quality monitoring and dolphin
monitoring were temporarily suspended during the reporting period.
Due to resources
arrangement, the noise monitoring at NMS5 was rescheduled from 2 January 2020
to 3 January 2020; from 8 January 2020 to 9 January 2020; and from 20 January
2020 to 21 January 2020.
There
were no works for Contract No. HY/2011/03 between 25 January
2020 and 31 January 2020. As such, weekly site inspection and 24-hr TSP monitoring (which was
scheduled on 29 January 2020), 1-hr TSP and noise monitoring (which was
scheduled on 30 January 2020) were suspended.
Due to power failure, 24-hr
TSP monitoring on 20 February 2020 at AMS5 (Ma Wan Chung Village) was
rescheduled to 21 February 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 (Dec 2019 to Feb 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 December 2019 to February 2020 are presented.
2) Dolphin monitoring was temporarily suspended
during the reporting period. Thus, no quarterly analysis of dolphin monitoring
results and exceedances from December 2019 to February 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 no 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.
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.
1.1.5
This is the thirtieth 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 December 2019 to 29
February 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
|
Loading and unloading of fill materials
|
Portion X
|
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
|
Finishing works for Highway Operation and
Maintenance Area Building
|
Portion X
|
Finishing works for Scenic Hill Tunnel West
Portal Ventilation building
|
West Portal
|
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 and dolphin monitoring 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)
|
Dec 2019
|
AMS5
|
77
|
24 - 234
|
352
|
500
|
AMS6
|
83
|
21 - 251
|
360
|
Jan 2020
|
AMS5
|
74
|
31 -124
|
352
|
AMS6
|
67
|
27 - 105
|
360
|
Feb 2020
|
AMS5
|
43
|
10 - 151
|
352
|
AMS6
|
51
|
14 - 137
|
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)
|
Dec 2019
|
AMS5
|
93
|
65 - 114
|
164
|
260
|
AMS6
|
89
|
73 - 113
|
173
|
Jan 2020
|
AMS5
|
67
|
33 - 113
|
164
|
AMS6
|
64
|
33 - 108
|
173
|
Feb 2020
|
AMS5
|
36
|
22 - 45
|
164
|
AMS6
|
37
|
23 - 46
|
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)
|
Dec 2019
|
NMS5
|
61
|
59 ¡V 63
|
When one documented complaint is received
|
75
|
Jan 2020
|
59
|
57 ¡V 62
|
Feb 2020
|
60
|
59 ¡V 60
|
3.3.2
No Action/Limit Level
exceedances for noise were recorded during daytime on normal weekdays of the
reporting period.
3.3.3
Major noise sources during the noise monitoring included
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 December 2019 to February 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 18 December
2019. 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
(December 2019)
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
810291.160
|
816678.727
|
0.950
|
810291.152
|
816678.713
|
1.116
|
S2
|
810958.272
|
815831.531
|
0.864
|
810958.255
|
815831.511
|
0.930
|
S3
|
810716.585
|
815953.308
|
1.341
|
810716.581
|
815953.303
|
1.441
|
S4
|
811221.433
|
816151.381
|
0.931
|
811221.428
|
816151.369
|
1.109
|
Table 3.10 Comparison
of Measurement
|
Comparison of measurement
|
Remarks and
Recommendation
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
-0.008
|
-0.014
|
0.166
|
Level continuously
increased
|
S2
|
-0.017
|
-0.020
|
0.066
|
Level continuously increased
|
S3
|
-0.004
|
-0.005
|
0.100
|
Level continuously increased
|
S4
|
-0.005
|
-0.012
|
0.178
|
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 December 2019 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)
|
02-Dec-2019
|
7.4
|
7.4
|
9.2
|
7.4
|
7.5
|
9.1
|
04-Dec-2019
|
7.3
|
8.7
|
11.8
|
7.3
|
9.2
|
10.8
|
06-Dec-2019
|
8.0
|
6.1
|
8.2
|
7.6
|
8.2
|
8.3
|
09-Dec-2019
|
7.8
|
6.8
|
9.6
|
7.8
|
7.9
|
8.1
|
11-Dec-2019
|
7.9
|
4.4
|
5.3
|
7.9
|
4.4
|
4.8
|
13-Dec-2019
|
7.7
|
7.7
|
9.1
|
7.8
|
6.6
|
9.4
|
16-Dec-2019
|
7.3
|
8.8
|
12.1
|
7.5
|
9.4
|
12.3
|
18-Dec-2019
|
7.1
|
8.8
|
11.0
|
7.0
|
14.6
|
11.8
|
20-Dec-2019
|
6.9
|
12.4
|
17.4
|
7.1
|
13.8
|
17.0
|
23-Dec-2019
|
7.2
|
11.3
|
12.7
|
7.0
|
12.3
|
11.2
|
25-Dec-2019
|
7.2
|
7.0
|
9.0
|
7.1
|
8.2
|
9.0
|
27-Dec-2019
|
7.0
|
12.2
|
11.5
|
6.7
|
12.8
|
11.2
|
30-Dec-2019
|
7.1
|
7.0
|
5.5
|
7.0
|
7.9
|
5.7
|
Average
|
7.4
|
8.3
|
10.2
|
7.3
|
9.4
|
9.9
|
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 December 2019 (totally 4 sampling days on 4th, 5th, 19th and 20th
December 2019).
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 4th, 5th, 19th
and 20th December 2019, which were cool and dry 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 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 4th (for ST), 5th (for TC1),
19th (for TC2) and 20th (for TC3) December 2019, which
were cool and dry days.
Intertidal Soft Shore Communities
3.6.11
The intertidal soft shore community surveys were conducted in low tide
period on 4th (for ST), 5th (for TC1),
19th (for TC2) and 20th (for TC3) December 2019. 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 10 and 4 individuals of Carcinoscorpius rotundicauda and Tachypleus
tridentatus were found in present survey. The
recorded individuals were mainly distributed along the shoreline from TC3 to
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 For Carcinoscorpius rotundicauda,
more
individuals (9 ind.) were found in ST with average body size 30.03mm (prosomal
width ranged 24.6 ¡V 35.14mm). In TC3, an individual with
body size 25.41mm was found in present survey. The search records in ST (1.5
ind. hr-1. person-1) and TC3 (0.17 ind. hr-1.
person-1) were very low. No
Carcinoscorpius rotundicauda was found in
TC1, TC2 in present survey.
3.6.18 For Tachypleus tridentatus, 3
individuals with average body size 30.21mm (prosomal width ranged 28.64 ¡V 31.5mm) were found in ST. In TC3, an
individual with body size 65.3mm was found in present survey. The search
records in ST (0.5 ind. hr-1. Person-1) and TC3 (0.17
ind. hr-1. Person-1) were very
low. No Tachypleus tridentatus was found
in TC1, TC2 in present survey.
3.6.19 No mating pair or large individual (≥100mm) was found in
present survey.
3.6.20
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, one pair of Tachypleus tridentatus with large body sizes
(male 150mm and Female 200mm; Male 180mm and Female 220mm) was found. Another mating pair was found in ST (male 140mm and Female 180mm). (Figure 3.2 of Appendix O) shows the photographic records of all 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. These mating pairs 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).
3.6.21
Despite of mating pair, there were occasional records of large individuals
of Carcinoscorpius rotundicauda (prosomal width ranged 114.45 ¡V
178.67 mm, either single or in pair) and
Tachypleus tridentatus (prosomal width 103 mm) (Figure 3.4 of Appendix O). 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. 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. 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.
3.6.22
No marked individual of horseshoe crab was recorded in the 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.
3.6.23 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
3.6.24
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.
3.6.25
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 September 2019, the search records
of Carcinoscorpius rotundicauda change from very low to low while the
change of Tachypleus tridentatus was similar during this period. Relatively higher population fluctuation of Carcinoscorpius rotundicauda was observed in TC3.
3.6.26
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.
3.6.27 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 March 2019. 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. In September
2019 (present survey), the sizes of the horseshoe crabs were decrease. It is
believed that the size of horseshoe crabs would be gradually rise afterward due
to the stable growth of juveniles after the spawning season.
3.6.28 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 a mating pair of Carcinoscorpius
rotundicauda was once found in TC2, the hatching rate and survival rate of
newly hatched individuals were believed very low.
Seasonal variation of horseshoe crab population
3.6.29
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 March 2019, 3 individuals of Carcinoscorpius rotundicauda were observed in TC2. However, all of
them 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. Throughout the monitoring period, similar
distribution of horseshoe crabs population were found in March. Most of the
horseshoe crabs were found in TC3 and ST.
3.6.30
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.
3.6.31
From September 2012 to December 2013, Carcinoscorpius rotundicauda was less common species relative to Tachypleus tridentatus. Only 4
individuals were ever recorded in ST in December 2012. This species had ever
been believed of very low density in ST hence the encounter rate was very low.
In March 2014, it was found in all sampling zones with higher abundance in ST.
Based on its average size (mean prosomal width 39.28-49.81 mm), it indicated
that breeding and spawning of this species had occurred about 3 years ago along
the coastline of Tung Chun Wan. However, these individuals were still small
while their walking trails were inconspicuous. Hence there was no search record
in previous sampling months. Since March 2014, more individuals were recorded
due to larger size and higher activity (i.e. more conspicuous walking trail).
3.6.32
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 December
2019 (present survey), the population size was low while natural mortality was
the possible cause.
3.6.33
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 in 2018, 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
3.6.34 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.
3.6.35
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
(present survey), an individual with larger body size (prosomal width 65mm) was
found in TC3 which reflected the stable growth of individuals. Across the whole monitoring
period, the larger juveniles (upper whisker) usually reached 60 ¡V 80 mm in prosomal width,
even 90 mm occasionally. Juveniles reaching this size might gradually migrate
to sub-tidal habitats.
Box
plot of horseshoe crab populations in ST
3.6.36 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.
3.6.37 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.
3.6.38
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.
3.6.39
In March 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. In September to December 2019,
the population size of both horseshoe crab species in TC3 and ST gradually
increased to low
¡V moderate level while their
body sizes were mostly in small to medium range (~25 ¡V 50mm).
Impact of the HKLR
project
3.6.40 It was
the 29th 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
3.6.41
Only seagrass species Halophila
ovalis was found in present survey, which was found in
TC3 and ST. In ST, there were
one 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 rand had area ~1000 m2 in
high vegetation coverage (90 ¡V 100%). At close vicinity, a small sized (~50 m2)
of Halophila
ovalis beds in low vegetation coverage (10-20%) were observed at tidal zone 1.5 ¡V 2.0 m
above C.D. In TC3, a small patch of Halophila ovalis
was found at tidal zone 1.5 ¡V 2.0m above
C.D. This seagrass patch had areas 9 m2
in high vegetation coverage (90 ¡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.
3.6.42
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.
3.6.43
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
3.6.44
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 March 2013 that grew within the large patch of
seagrass Halophila ovalis. Then, the patch size increased and merged
gradually with the warmer climate from March to June 2013 (15 m2).
However, the patch size decreased and remained similar from September 2013 (4 m2)
to March 2014 (3 m2). In June 2014, the patch size increased
obviously again (41 m2) with warmer climate followed by a decrease
between September 2014 (2 m2) and December 2014 (5 m2).
From March to June 2015, the patch size increased sharply again (90 m2).
It might be due to the disappearance of the originally dominant seagrass Halophila
ovalis resulting in less competition for substratum and nutrients. From
September 2015 to June 2016, it was found coexisting with seagrass Halophila
ovalis with steady increasing patch size (from 44 m2 to 115 m2)
and variable coverage. In September 2016, the patch size decreased again to (38
m2) followed by an increase to a horizontal strand (105.4 m2)
in June 2017. And it did no longer co-exist with Halophila ovalis.
Between September 2014 and June 2017, an increasing trend was noticed from
September to June of next year followed by a rapid decline in September of next
year. It was possibly the causes of heat stress, typhoon and stronger grazing
pressure during wet season. However, such increasing trend was not found from
September 2017 to December 2019 (present survey) while no patch of Zostera
japonica was found.
3.6.45
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.
3.6.46
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
3.6.47
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.
3.6.48 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).
3.6.49
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.
3.6.50
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
3.6.51 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
3.6.52 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.
3.6.53 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.
3.6.54 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.
3.6.55 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). In September 2019 and December 2019,
the seagrass bed area slightly decreased to 1050 m2 which were in
normal fluctuation.
Impact of the HKLR project
Intertidal Soft Shore Communities
Substratum
3.6.57
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: 80%; M:
80%) were recorded at high
and mid tidal levels. Relatively higher percentages of ¡¥Gravels and Boulders¡¦
(50%) and ¡¥Soft mud¡¦(40%)
were recorded at low tidal level.
¡P
In TC2, high percentages of ¡¥Gravels and Boulders¡¦ (H: 80%; M: 60%) were
recorded at high and mid tidal levels. Relatively higher percentages of
¡¥Gravels and Boulders¡¦ (40%) and ¡¥Soft mud¡¦ (40%) were recorded at low tidal
level.
¡P
In TC3, higher percentage of ¡¥Gravels and Boulders¡¦ (60%) was recorded followed
by ¡¥Sand¡¦ (30%) at high tidal level. At mid tidal level, higher percentages of
¡¥Gravels and Boulders¡¦ (60%) and ¡¥Sand¡¦ (30%) were recorded. At low tidal
level, the main substratum type was ¡¥Gravels and Boulders¡¦ (70%).
¡P
In ST, ¡¥Gravels and Boulders¡¦ was the main substratum type
(H:80%; M: 80%) 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%).
3.6.58
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
3.6.59
Table 3.4 of Appendix O lists the total abundance, density and number of taxon of every phylum in
this
survey. A total of 13803 individuals were recorded. Mollusca was the most abundant phylum (total
abundance 13083 ind, density 436 ind. m-2, relative abundance 94.8%). The second was Arthropoda (577 ind., 19 ind. m-2,
4.2%).
Relatively other phyla were very low in abundances (density <2 ind. m-2,
relative abundance £0.4%). Moreover, the most diverse phylum was Mollusca (32 taxa) followed by Arthropoda (7 taxa)
and Annelida (6 taxa). There were
2 taxa recorded for Sipuncula and 1 taxon for other phyla.
3.6.60 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
3.6.61
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 (2667- 4111 ind.) varied among the four sampling
zones while the
phyla distributions were
similar. In general, Mollusca was the most dominant phylum (no. of individuals: 2394 - 3898 ind.; relative abundance 89.8 ¡V 97.3%; density
319 - 520 ind. m-2).
Other phyla were much
lower in number of individuals.
Arthropoda (70 - 222 ind.; 1.9 ¡V 8.3%; 9 - 30 ind. m-2) and Annelida (0 - 37 ind.; 0.0 ¡V
1.4%; 0 - 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
3.6.62
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 (42-100 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.
3.6.63
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 122 ind. m-2; relative abundance 27%),
the gastropods Batillaria multiformis (76 ind. m-2; relative
abundance 17%) and Monodonta
labio (64 ind. m-2; relative abundance 14%)
were of abundant species found at low-moderate densities. At mid tidal level, the rock oyster Saccostrea
cucullata (140 ind. m-2, 30%) was of dominant
species with high density. Meanwhile, the gastropod Monodonta labio (60
ind. m-2, 13%) was at low - moderate density. At low tidal level
(main substratum types ¡¥Gravels and Boulders¡¦
or ¡¥Soft mud¡¦), the rock oyster Saccostrea cucullata (152 ind. m-2,
26%) was dominant at high density. The gastropod Monodonta labio (99
ind. m-2, 17%) was found at moderate density.
3.6.64
In TC2, the substratum types were mainly ' Gravels and Boulders' at high tidal level. Gastropod Batillaria multiformis (112 ind. m-2,
22%) was of abundant species at high density and the rock oyster Saccostrea
cucullata (98 ind. m-2, 19%) was found at moderate
density. At mid tidal level (major
substratum type ¡¥Gravels and Boulders¡¦), rock
oyster Saccostrea cucullata (149 ind. m-2, 25%) and gastropod Batillaria multiformis (104 ind. m-2,
18%) were of dominant species at high densities. Meanwhile, gastropod Monodonta labio (72 ind. m-2,
12%) was of abundant species at low- moderate density. Substratum types
¡¥Gravels and Boulders; and ¡¥Soft mud¡¦ were evenly distributed at low tidal
level, rock oyster Saccostrea cucullata (162 ind. m-2, 29%)
was abundant species at high density and the gastropod Monodonta labio
(84 ind. m-2, 15%) was at low - moderate density.
3.6.65 In TC3, the substratum types were
mainly ¡¥Gravels and Boulders¡¦ at high tidal level. The rock oyster Saccostrea
cucullata (82 ind. m-2, 26%) and the gastropod Batillaria
multiformis (53 ind. m-2, 18%) were of abundant species at low ¡V
moderate densities. At mid tidal level, ¡¥Gravels and Boulders¡¦ and ¡¥Sand¡¦ were
the mainly substratum types. The gastropod Batillaria multiformis (68
ind. m-2, 22%) was of common species, and followed by the rock
oyster Saccostrea cucullata (58 ind.m-2, 19%). Both of them
were at low - moderate 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, 36%) at high density.
3.6.66 In ST, the major substratum type was ¡¥Gravels and Boulders¡¦ at
high tidal level. At high tidal level, the
rock oyster Saccostrea cucullata (68 ind. m-2, 26%) and the gastropod
Monodonta labio (44 ind. m-2, 17%) were abundant
at low ¡V moderate densities. At mid tidal level, the main substratum
type was ¡¥Gravels and Boulders¡¦. The rock
oyster Saccostrea cucullata (74
ind. m-2, 18%), the gastropods Batillaria zonalis (75 ind. m-2, 14%) and
Monodonta labio (66 ind. m-2, 12%) were of abundant species at
low - moderate densities. At low tidal level (major substratum: ¡¥Gravals and Boulders¡¦), rock oyster Saccostrea
cucullata (126 ind. m-2, 25 %, attached on boulders) was dominant at high density and followed by gastropod Monodonta
labio (56 ind. m-2, 11 %) at
low - moderate density.
3.6.67
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 (2238 ind.), gastropods Monodonta labio (796 ind.) and Batillaria
multiformis (740 ind.) were the most common species on gravel and boulders
substratum. Rock oyster Saccostrea cucullata (S: 731 ind.¡¦ M: 561 ind.) was the most common species on sandy and soft mud
substrata.
Biodiversity
and abundance of soft shore communities
3.6.68
Table
3.7 of Appendix
O shows the mean values of species number,
density, 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.
3.6.69
Among the sampling zones, the mean species number was similar
(13 ¡V 15 spp. 0.25 m-2) among the four sampling zones. The mean
densities of TC2 (548 ind. m-2) was higher than TC1 (498 ind. m-2)
followed by ST (439 ind. m-2) and TC3 (355 ind. m-2). The higher densities of TC1 and
TC2 are due to the relatively high number of individuals in each quadrat. TC2
and ST were relatively higher in H¡¦ (2.20 and 2.17) and followed by TC1 (2.13)
and TC3 (2.03). Comparing with TC1 and TC3 (J: 0.79), TC2 and ST were higher in
J (0.82) which were due to their
higher species number and even taxa distribution.
3.6.70
In the present survey, no clear trend of mean species number, mean
density, H¡¦ and J observed among the tidal level.
3.6.71
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.
3.6.72
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 December 2019, 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
3.6.73
It was the 29th 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 December 2019 to February 2020 are presented.
4.2.1
There was no complaint received in relation to the environmental impacts
during this reporting period.
The details of cumulative statistics of Environmental Complaints are provided
in Appendix
N.
4.2.2
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 spraying water to the excavated material prior to/during excavator operation
at WA3.
¡P
The Contractor was reminded
to remove the waste from N4, S7, PR14, LCSD Depot.
¡P
The Contractor was reminded
to remove the accumulated waste from PR14 and LCSD Depot.
¡P
The Contractor was reminded
to remove the waste on the ground at LCSD Depot.
¡P
The Contractor was reminded
to remove the general refuse/construction waste on the ground at S7.
¡P
The Contractor was reminded
to remove the wasted planks at LCSD Depot.
¡P
The Contractor was reminded
to provide a drip tray for the oil drum at N13.
¡P
The Contractor was reminded
to provide drip tray for the chemical containers at S7 and PR14.
¡P
The Contractor was reminded
to provide proper chemical labels for the oil drum and chemical container at
PR14.
¡P
The Contractor was reminded
to clear the stagnant water inside the drip tray at PR14.
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 thirtieth Quarterly EM&A Report which summarizes the monitoring results and
audit findings of the EM&A programme during the reporting period from 1 December 2019 to 29 February 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
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 December 2019 to February 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.
Mudflat - Ecology
5.3.7
The December 2019 survey results indicate that the impacts of the HKLR
project were not be 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 December 2019 (present survey) which was in
normal fluctuation.
Environmental Site Inspection and Audit
5.3.8
Environmental site inspection was carried out on 3, 11, 17 and 27 December 2019; 2, 8, 15 and 22 January 2020; and 7, 12, 19 and 28 February 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.