2.1 According to EM&A Manual
Section 10.3.4, acoustic behavior and movement of Chinese White Dolphin near
the bored piling sites should be monitored during bridge construction.
2.3
The EARs were deployed at two locations: 1) near the bridge alignment (N22°17.222,
E113°53.016), about 500 m from the first three bored piling sites (P48, P50
& P52 - Site B2), and 2) at a less disturbed site away from the bridge
alignment as control site, off Fan Lau (N22°11.827, 113°50.648; Site B1). EAR B2 was in water depth 4 m, and EAR
B1 in 7 m. The location of Site B1 and B2 are shown in Figure 2.
2.4
Thirty days of monitoring during bored piling activities
were carried out during the construction phase.
2.5
In March 2013, a total of 23
days of acoustic monitoring surveys were conducted between March 6th
and 30th
2013. A total of 8 days and 2 days of acoustic monitoring surveys were
conducted during the bored piling activities for P48 and P52 respectively.
2.6
In April 2013, a total of 8
days of acoustic monitoring surveys were conducted on the 1st, 2nd,
3rd, 5th, 7th, 8th, 10th
and 11th
April 2013, when bored piling activities were
concurrently conducted at Piers 48 and 52.
2.7
In July 2013, a total of 12
days of acoustic monitoring surveys were conducted on the 9th, 11th,
12th, 15th, 16th, 17th, 18th,
22nd, 23rd, 24th, 25th and 26th,
when bored piling activities were concurrently conducted.
2.8
The dolphin acoustic behaviour monitoring schedule is shown in Appendix B.
2.9
A total of 30 days of acoustic
monitoring surveys were conducted in March, April and July 2013, when bored piling
activities were concurrently conducted. During those dates, 2,751.8 km of
survey effort were conducted to search for dolphins in the western and
northwestern waters of Lantau. A
total of 91 groups, numbering 301 dolphins, were sighted during these
surveys. In addition, 67 sound
samples of recordings were taken from the surveys. Moreover, the EARs were deployed at Fan
Lau (site B1) and near the bridge alignment (Site B2).
2.10
Detailed monitoring methodology
and results can be found in Appendix C.
2.11 According to the Dolphin Acoustic Behaviour
Monitoring Impact Phase Monitoring Report prepared by Dolphin Specialist as shown in Appendix C, summary of the dolphin acoustic
behavior monitoring results is shown in Table
2.1.
Table 2.1. Values of the two response variables of dolphin acoustic behaviour collected
by calibrated hydrophone (average clicks and whistles per minutes) by size of
group, behavioural state and time of day during baseline and impact monitoring
periods. (The numerical values
highlighted in blue indicated that the values recorded in impact monitoring
period have triggered the Action Level (20% higher or lower than the baseline
period), while the ones highlighted in red indicated a triggering of Limit
Level (40% higher or lower than the baseline period). Only the cells
highlighted in yellow have found significant differences between the values
recorded in impact and baseline monitoring periods, while no significant
difference was found in other comparisons even though some have triggered the
Action or Limit Level.)
|
Average clicks per
minute ( ± s.d.) |
Average whistles per
minute ( ± s.d.) |
|
Group Size |
|||
1 dolphins |
Baseline |
62.19 ± 77.73 (n=21) |
0.21 ± 1.49 (n=19) |
Impact |
119.11 ± 201.67 (n=11) |
0.13 ± 0.30 (n=11) |
|
2-5 dolphins |
Baseline |
54.03 ± 179.32 (n=82) |
0.56 ± 1.70 (n=126) |
Impact |
54.17 ± 95.45 (n=46) |
0.09 ± 0.20 (n=46) |
|
6-9 dolphins |
Baseline |
118.00 ± 310.31 (n=23) |
1.58 ± 4.63 (n=38) |
Impact |
106.06 ± 199.58 (n=26) |
0.97 ± 1.99 (n=26) |
|
10+ dolphins |
Baseline |
289.33 ± 140.58 (n=20) |
2.74 ± 1.99 (n=36) |
Impact |
n/a |
n/a |
|
Behavioural State |
|||
Feeding |
Baseline |
30.95 ± 69.90 (n=16) |
0.62 ± 1.33 (n=29) |
Impact |
19.30 ± 29.62 (n=11) |
0.16 ± 0.26 (n=11) |
|
Milling |
Baseline |
71.29 ± 205.44 (n=90) |
0.66 ± 1.85 (n=139) |
Impact |
80.09 ± 136.86 (n=54) |
0.18 ± 0.60 (n=54) |
|
Socializing |
Baseline |
287.48 ± 326.22 (n=20) |
3.78 ± 4.14 (n=26) |
Impact |
213.12 ± 309.71 (n=7) |
2.48 ± 3.16 (n=7) |
|
Traveling |
Baseline |
13.16 ± 208.94 (n=11) |
0.25 ± 1.48 (n=12) |
Impact |
52.34 ± 32.53 (n=7) |
0.17 ± 0.29 (n=7) |
|
Resting |
Baseline |
0.10 ± 70.35 (n=2) |
0.13 ± 1.43 (n=6) |
Impact |
n/a |
n/a |
|
Time of day |
|||
|
Baseline |
38.14 ± 69.90 (n=15) |
0.70 ± 1.33 (n=29) |
Impact |
74.39 ± 124.79 (n=31) |
0.32 ± 0.75 (n=31) |
|
|
Baseline |
79.97 ± 144.51 (n=68) |
0.68 ± 1.86 (n=94) |
Impact |
110.73 ± 218.62 (n=26) |
0.66 ± 1.78 (n=26) |
|
|
Baseline |
159.41 ± 303.43 (n=44) |
1.74 ± 3.80 (n=62) |
Impact |
43.35
± 72.50 (n=17) |
0.03
± 0.08 (n=17) |
|
|
Baseline |
65.40 ± 140.58 (n=17) |
1.16 ± 1.99 (n=36) |
Impact |
49.90 ± 69.04 (n=12) |
0.42 ± 1.20 (n=12) |
Event and Action Plan
2.12
The detailed Event and Action
Plan is presented in Table 2.3.
Table 2.3 Event and Action Plan on
Dolphin Acoustic Behaviour
EVENT |
ACTION |
|||
ET Leader |
IEC |
SO |
Contractor |
|
Action Level With the numerical values presented in
Table 1, when any of the response variable for dolphin acoustic behaviour
recorded in the construction phase monitoring is 20% lower or higher than that recorded in the baseline
monitoring, or when there is a shift of 3 hours or more in peak
occurrence at B2 Site (i.e. 00:00 – 01:00), the action level should be triggered |
1.
Repeat statistical data analysis to confirm findings; 2. Review
all available and relevant data to ascertain if differences are as a result
of natural variation or seasonal differences; 3. Identify source(s) of impact; 4.
Inform the IEC, SO and Contractor; 5. Check monitoring data; 6.
Carry out audit to ensure all dolphin protective measures are implemented
fully and additional measures be proposed if necessary |
1.
Check monitoring data submitted by ET and Contractor; 2.
Discuss monitoring with the ET and the Contractor; |
1.
Discuss with the IEC the repeat monitoring and any other measures proposed by
the ET; 2.
Make agreement on measures to be implemented. |
1.
Inform the SO and confirm notification of the non- compliance in writing; 2.
Discuss with the ET and the IEC and propose measures to the IEC and the SO; 3. Implement
the agreed measures. |
Limit Level With the numerical values presented in
Table 1, when any of the response variable for dolphin acoustic behaviour
recorded in the construction phase monitoring is 40% lower or higher than that recorded in the baseline
monitoring, or when there is a shift of 6 hours or more in peak occurrence at B2 Site (i.e. 00:00 – 01:00), the limit level should be triggered |
1.
Repeat statistical data analysis to confirm findings; 2.
Review all available and relevant data to ascertain if differences are as a
result of natural variation or seasonal differences; 3. Identify source(s) of impact; 4.
Inform the IEC, SO and Contractor; 5. Check monitoring data; 6.
Carry out audit to ensure all dolphin protective measures are implemented
fully and additional measures be proposed if necessary 7.
Discuss additional dolphin monitoring and any other potential mitigation
measures (e.g. consider to temporarily stop relevant portion of construction
activity) with the IEC and Contractor. |
1.
Check monitoring data submitted by ET and Contractor; 2.
Discuss monitoring with the ET and the Contractor; 3.
Review proposals for additional monitoring and any other measures submitted
by the Contractor and advise ER accordingly. |
1.
Discuss with the IEC the repeat monitoring and any other measures proposed by
the ET; 2.
Make agreement on measures to be implemented. |
1.
Inform the SO and confirm notification of the non- compliance in writing; 2.
Discuss with the ET and the IEC and propose measures to the IEC and the SO; 3.
Implement the agreed measures. |
Abbreviations: ET
– Environmental Team, IEC – Independent Environmental Checker, SO – Supervising
Officer
2.13
Detailed monitoring methodology
and results can be found in Appendix C.
2.14
According to Table 2.1, there were four Action Level (AL) exceedances and four Limit Level
(LL) exceedances in the clicking rates, while there were three AL exceedances
and seven LL exceedances in the whistling rates. However, only
significant differences were found in both the whistling and clicking rates
recorded in the afternoon time period between 13:00 and 14:59.
2.15
As the Environmental Team of the Contract, all the monitoring data and statistical data analysis as
presented in Appendix C have been
checked and reviewed according to Table
2.3.
2.16 No direct evidence that the
exceedances were due to the bored piling activities under the Contract
according to the Dolphin Acoustic Behaviour
Monitoring Impact Phase Monitoring Report in Appendix
C:
Ø
The majority of the exceedances are not statistically significant due to
small sample size;
Ø
Different type of vessels recorded during baseline and construction may
contribute the significant different values of response
variables between
baseline and construction phases;
Ø
Natural seasonal variation including the addition of strong seasonal
fish chorusing, and that other than anthropogenic influences may cause the
different dolphins’ acoustic behaviour between baseline and construction phase
dolphin monitoring;
Ø
The change in peak
occurrence does not only occur at the site of impact (Site B2) but also at the
control site (Site B1);
Ø
The decrease in number of sightings was also mainly occurred in Zone 1
and Zone 3 which were away from the construction site of the Contract according
to Figure 9a and 9b in Appendix C;
Ø
Significant increases in the ambient noise
levels measured at both sites B1 and B2 during the construction phase which may affect the dolphins’
acoustic behaviour.
Implementation Status of Environmental Mitigation Measures
2.17 In order to minimize impact on dolphins’ acoustic behaviour, dolphin protection measures as
described below were properly implemented during the marine works for the
Contract:
Ø
Regular marine travel route for marine vessels were implemented properly
in accordance with the submitted plan and relevant records were kept properly.
Ø
Acoustic decoupling measures for the stationary equipment (generators,
winch generators and air compressors) mounted on boards were adopted according
to the approved Acoustic Decoupling Measures Plan, EP Condition 3.7 and
EM&A Manual, Section 10.2.18.
Ø
Dolphin exclusion zone and dolphin watching plan according to EM&A
Manual, Section 10.2.12 and 10.2.17 respectively.