1.1 Purpose of the
Report
1.2 Structure of the
Report
2.1 Background
2.2 Marine
Construction Works Undertaken during Reporting Week
2.3 Status of
Environmental Approval Documents
3 Water Quality Monitoring
Requirements
3.1 Monitoring
Locations
3.2 Monitoring
Parameters and Frequency
3.3 Monitoring
Equipment and Methodology
4.1 Data Collected
During Mid-Ebb and/or Mid-Flood Tidal Conditions
4.2 Continuous
In-Situ Measurement Data
5 Environmental
Non-CONFORMANCES
5.1 Summary of
Environmental Exceedance
5.2 Summary of
Environmental Complaint
5.3 Summary of
Environmental Summons and Prosecution
6.1 Key Issues For
The Coming Month
6.2 Monitoring
Schedule For The Coming Month
LIST
OF TABLES
Table
2.1 Summary of Marine Works Undertaken During
the Reporting Week
Table 2.2 Summary of Environmental Licensing,
Notification, Permit and Reporting Status
Table 3.1 Co-ordinates of Starting Points and Ending
Points for Zones A to E (HK Grid)
Table 3.2 Co-ordinates of All Monitoring Stations
(HK Grid)
Table 3.3 Monitoring Frequency and Parameters for
Impact Monitoring
Table 3.4 Action and Limit Levels of Water Quality
for Zones A and E
Table 3.5 Action and Limit Levels of Dissolved Oxygen
and Turbidity for Zones B to D
Table 3.6 Action and Limit Levels of Suspended
Solids for Impact Stations F1, C1, C2, and C3
LIST
OF ANNEXES
|
Annex
A |
|
|
Annex
B |
|
|
Annex
C |
|
|
Annex
D |
LIST
OF Figure
|
Figure
2.1 |
|
|
Figure 3.1 |
The construction works for
the VSNL Intra Asia Submarine Cable System –
Summary of Construction Works undertaken during the
Reporting Period
Due
to weather constraints, the working vessel continued to be on a four point
mooring in Zone A on 29 May 2009. Installation of cable along the proposed
route was undertaken in Zones A to E on 30 May and 31 May 2009. Phase III cable installation works were
completed on 2 June 2009 and the working vessel returned to
Water
Quality
Three
monitoring events were scheduled between 29
May and 4 June 2009.
All monitoring events at all designated monitoring stations were
performed on schedule, ie on 29 May, 30 May and 31
May 2009.
Environmental
Non-conformance
Daily
exceedances of Action and Limit Levels for dissolved
oxygen were recorded on the three monitoring events (ie
29 May, 30 May and 31 May 2009).
Depth-averaged turbidity and suspended solids were generally compliant with the Action and Limit
Levels with the exception of 29 May 2009.
Results of the detailed investigation indicated that none of the exceedances were attributed to the Project construction
works.
No
complaints were received during the
reporting week.
No environmental summons/prosecution were received during the reporting week.
Future Key Issues
As
there will be no cable installation works in the following weeks, the impact
monitoring will be suspended and the post-project monitoring will take place in
early July 2009 after the completion of the grout mattress installation at the
crossing of Tata’s cable system and HKE's
gas pipeline in south east
ERM-Hong Kong, Limited (ERM) was appointed
by Tata Communications (Bermuda) Ltd (formerly Videsh Sanchar Nigam
Limited (VSNL)) as the Monitoring Team (MT) to implement
the Environmental Monitoring and Audit (EM&A) programme for the VSNL Intra
Asia Submarine Cable System –
This is the fifth Weekly Impact Monitoring
Report, which summarises the
impact monitoring results and audit findings for the EM&A programme during
the reporting period from 29 May to 4 June 2009.
The structure of the report is as follows:
Section
1 : Introduction
Details the background, purpose and structure of the
report.
Section
2 : Project
Information
Summarises
background and scope of the project, the construction works undertaken and the
status of Environmental Permits/Licenses during the reporting period.
Section
3 : Water
Quality Monitoring Requirements
Summarises the
monitoring parameters, monitoring programmes, monitoring methodologies,
monitoring frequency, monitoring locations, Action and Limit Levels, and Event
/ Action Plans.
Section
4 : Monitoring
Results
Summarises the monitoring results obtained in the reporting period.
Section
5 : Environmental
Non-conformance
Summarises
any monitoring exceedance, environmental complaints
and environmental summons within the reporting period.
Section
6 : Future
Key Issues
Summarises the
monitoring schedule for the next week.
Section
7 : Conclusions
Presents the key findings of the impact
monitoring results.
Tata
Communications (Bermuda) Ltd (formerly Videsh Sanchar Nigam Limited (VSNL)) proposes to install a submarine
telecommunications cable, which will run from
In
August 2007, a Project Profile (PP) included an
assessment of the potential environmental impacts associated with the
installation of the submarine cable circuit was prepared and submitted to the
Environmental Protection Department (EPD) under section 5.(1)(b) and 5.(11) of the
Environmental Impact Assessment Ordinance (EIAO) for application for
Permission to apply directly for an Environmental Permit (EP). The Environmental Protection Department,
subsequently issued an Environmental Permit (EP-294/2007) and Further
Environmental Permit (FEP-01/294/2007).
Amendments to the permitting requirements were incorporated into the
Environmental Permit to address potential environmental impacts associated with
cable crossings over the HKE’s gas pipeline in
southeast
Baseline
Monitoring was conducted near
Impact
Monitoring has been carried out at
This report presents
results of the data from monitoring stations in Zones A to E during the cable
installation works. Results of the
impact monitoring data will therefore be compared against the results of the Baseline Environmental Monitoring Part A
and Part B.
2.2
Marine
Construction Works Undertaken during Reporting Week
The
cable installation barge “CB Networker” installs the cable in three phases:
·
Phase
I – Locate in-service cables by divers (completed);
·
Phase
II – Conduct route clearance and pre-lay trial run of burial tool “Injector”
(completed); and
·
Phase
III – Install cable along the proposed route using the burial tool “Injector”.
A
summary of the major works undertaken during the reporting week is shown in Table 2.1.
Table 2.1 Summary
of Marine Works Undertaken During the Reporting Week
|
Date |
Works Area |
Activity |
|
Zone A |
Weather downtime |
|
|
30 May 2009 |
Zones A and E |
Installation of cable along the proposed route
using the burial tool “Injector” |
|
31 May 2009 |
Zones B to D |
Installation of cable along the proposed route
using the burial tool “Injector” |
|
1 June 2009 |
Outside Zones A to E |
Installation of cable along the proposed route
using the burial tool “Injector” |
|
2 June 2009 |
Outside Zones A to E |
Installation of cable along the proposed route
using the burial tool “Injector”.
Vessel docked alongside |
|
3 June 2009 |
Demobilisation |
|
|
4 June 2009 |
|
Demobilisation |
2.3
Status of
Environmental Approval Documents
A
summary of the relevant permits, licences, notifications and/or reports on
environmental protection for this Project is presented in Table 2.2.
Table 2.2 Summary
of Environmental Licensing, Notification, Permit and Reporting Status
|
Permit / Licence / Notification / Report |
Reference |
Validity Period |
Remarks |
|
Environmental Permit |
(EP-294/2007) |
Throughout the construction period |
Granted on 23 November 2008 |
|
Further Environmental Permit |
(FEP-01/294/2007) |
Throughout the construction period |
Granted on 9 July 2008 |
|
EM&A Manual |
- |
Throughout the construction period |
Approved by EPD on 12 March 2009 |
|
Baseline Water Quality Monitoring Report (Part A) |
- |
Throughout the construction period for Zones A and
E |
Approved by EPD on 1 April 2009 |
|
Baseline Water Quality Monitoring Report (Part B) |
- |
Throughout the construction period for Zones B to D |
Approved by EPD on 30 April 2009 |
In accordance with the EM&A Manual,
during the installation of the cable, water quality sampling was undertaken at
stations situated around the cable laying works at
·
S1
and S2 are situated at the two Seawater Intake Points in
·
S3 is
a Sensitive Receiver used to monitor the water quality condition of the Coastal Protection Areas
at
·
B1 is
an Impact Station used to monitor the effect of the construction activities on
·
R1 is
a Control Station for S1, S2, S3 and B1 at
·
C1,
C2 and C3 are located approximately 600 m north of the cable alignment at Po Toi for monitoring the effect of cable laying works on
coral communities in the area. The
water quality monitoring at C1 would be initiated when the cable installation barge entered Zone B. Similarly, the monitoring works were carried
out at C2 and C3 when the cable installation barge
moved inside Zones C and D, respectively;
·
F1 is
used to monitor the effect of the cable installation works on the Po Toi Fish Culture Zone (FCZ). It is approximately 1,500 m to the north
of the cable alignment, which is not supposed to be influenced by the cable
laying works due to its remoteness to the construction works. The water quality of the Po Toi FCZ was monitored when the cable
installation was undertaken inside Zones B to D;
·
R2
and R3 are Control Stations for C1, C2, C3 and F1 at Po Toi
which are not supposed to be influenced by the cable laying works due to their
remoteness to the construction works;
·
C4
and C5 are Impact Stations used to monitor the effect of cable laying works on
the water
quality conditions for the coral communities found at
·
R4 is
Control Station for C4 and C5 in Zone E.
It is not expected to be influenced by the construction works.
The
co-ordinates of each zone and the above monitoring stations are listed in Table 3.1 and Table 3.2, respectively.
Table 3.1 Co-ordinates
of Starting Points and Ending Points for Zones A to E (HK Grid)
|
Zone |
Starting
Point |
|
Ending
Point |
|
|
|
Easting |
Northing |
Easting |
Northing |
|
A |
837029.763 |
811601.699 |
836367.572 |
810545.975 |
|
B |
841917.597 |
802680.115 |
844161.823 |
801308.268 |
|
C |
844161.823 |
801308.268 |
845555.155 |
801495.491 |
|
D |
845555.155 |
801495.491 |
846970.152 |
801749.210 |
|
E |
836469.415 |
809294.174 |
837478.871 |
807740.633 |
Table 3.2 Co-ordinates
of All Monitoring Stations (HK Grid)
|
Station |
Nature |
Corresponding Control Station |
Easting |
Northing |
|
S1 |
Seawater
Intakes |
R1 |
836538.669 |
811528.535 |
|
S2 |
Seawater
Intakes |
R1 |
836195.047 |
810956.409 |
|
S3 |
Coastal
Protection Areas |
R1 |
836677.103 |
810666.744 |
|
B1 |
Gazetted
Beach |
R1 |
837241.114 |
811498.400 |
|
|
|
|
|
|
|
C1 |
Coral
Colonies |
R2,
R3 |
843547.181 |
802010.004 |
|
C2 |
Coral
Colonies |
R2,
R3 |
844800 |
801840 |
|
C3 |
Coral
Colonies |
R2,
R3 |
846179.538 |
802224.554 |
|
C4 |
Coral
Colonies |
R4 |
836863.233 |
808528.950 |
|
C5 |
Coral
Colonies |
R4 |
838197.242 |
808036.724 |
|
|
|
|
|
|
|
F1 |
Fish Culture Zone |
R2, R3 |
843920 |
802730 |
|
|
|
|
|
|
|
R1 |
Control Station |
- |
835951.109 |
809052.535 |
|
R2 |
Control
Station |
- |
842074.745 |
803375.183 |
|
R3 |
Control
Station |
- |
846444 |
804982 |
|
R4 |
Control
Station |
- |
835934.876 |
807347.391 |
3.2
Monitoring
Parameters and Frequency
The
impact water quality monitoring was conducted in accordance with the
requirements stated in the EM&A
Manual. These are presented
below.
3.2.1
Monitoring Parameters
Parameters measured in situ were:
·
dissolved oxygen (DO) (%
saturation and mg L-1);
·
temperature (°C);
·
turbidity (NTU); and
·
salinity (‰).
The only parameter measured
in the laboratory was:
·
suspended solids (SS) (mgL-1).
In addition to the water
quality parameters, other relevant data were measured and recorded in field
logs, including the location of the sampling stations, water depth, time,
weather conditions, sea conditions, tidal state, special phenomena and work
activities undertaken around the monitoring and works area that may influence
the monitoring results.
3.2.2
Monitoring Frequency
Impact Monitoring at S1, S2, S3, B1 and R1 took
place when the cable installation works were undertaken within 500 m (Zone A)
of monitoring stations S1, S2, S3 and B1.
The sampling works ceased when no cable installation works were
conducted inside Zone A.
Impact
Monitoring at C1, C2, C3, F1, R2 and R3 commenced when the cable installation barge was within Zones B, C or D
near Po Toi (coral colonies). The monitoring works were carried out at
C1 and F1 when the cable installation barge
moved inside Zone B. The water
quality monitoring at C2 and F1 was initiated once the cable installation barge
exited Zone B and entered Zone C.
Likewise, in situ measurements
and water samples were taken at C3 and F1 when the cable
installation was conducted inside Zone D. The sampling works halted upon the
demobilisation of the cable installation barge.
Impact
Monitoring at C4, C5 and R4 started when the cable
installation barge entered Zone E.
No monitoring works would be performed once the cable
installation barge left Zone E.
Impact
monitoring was carried out during the barge operating hours, normally covering
both mid-flood and mid-ebb tidal conditions, until water quality monitoring was
not required.
In-situ
and SS data of the control and impact stations within the impact zone were
collected daily during mid-flood and mid-ebb tidal states (Table 3.3), unless the mid-ebb tide and/or the mid-flood tide were
not occurring during the monitoring period. In addition, continuous in-situ measurements were taken at the
impact monitoring stations, ie C1-5, B1, F1 &
S1-3, at 30- to 60- minute intervals (subject to the weather conditions and
travelling time between stations) within the zone subject to monitoring. The monitoring frequency and parameters
for Impact Monitoring are summarised in Table
3.3.
Table 3.3 Monitoring
Frequency and Parameters for Impact Monitoring
|
Zone |
Station Type |
Monitoring Station |
Monitoring Frequency |
Monitoring Parameter |
|
|
Mid-ebb Tide / Mid-flood Tide |
30- to 60- Minute Interval |
||||
|
A |
Control |
R1 |
Daily when cable installation works undertaken in
Zone A |
Temperature, Turbidity, Salinity, DO, SS |
- |
|
Impact |
S1, S2, S3 and B1 |
Temperature, Turbidity, Salinity, DO |
|||
|
B |
Control |
R2 and R3 |
Daily when cable installation works undertaken in
Zone B |
- |
|
|
Impact |
C1, F1 |
Temperature, Turbidity, Salinity, DO |
|||
|
C |
Control |
R2 and R3 |
Daily when cable installation works undertaken in
Zone C |
- |
|
|
Impact |
C2, F1 |
Temperature, Turbidity, Salinity, DO |
|||
|
D |
Control |
R2 and R3 |
Daily when cable installation works undertaken in
Zone D |
- |
|
|
Impact |
C3, F1 |
Temperature, Turbidity, Salinity, DO |
|||
|
E |
Control |
R4 |
Daily when cable installation works undertaken in
Zone E |
- |
|
|
Impact |
C4 and C5 |
Temperature, Turbidity, Salinity, DO |
|||
3.3
Monitoring
Equipment and Methodology
3.3.1
Monitoring Equipment
Dissolved Oxygen, Temperature, Salinity, Turbidity Measuring Equipment
The instrument was a portable, weatherproof multi-parameter measuring
instrument (YSI 6820) complete with cables, multi-probe sensor, comprehensive
operation manuals, and was operable from a DC power source. It was capable of measuring:
·
dissolved oxygen levels in
the range of 0 – 50 mg L-1; and 0-500% saturation;
·
temperature of -5 to 50 °C;
·
turbidity levels between
0-1000 NTU (response of the sensor was checked with certified standard
turbidity solutions before the start of measurement); and,
·
salinity in the range of 0-40 ppt (checked with 30 ppt Salinity solutions before the start of the
measurement).
Water Depth Gauge
The water depth gauge affixed to the bottom of the water quality
monitoring vessel was used.
Current Velocity and Direction
Current velocity and direction was estimated by conducting float
tracking.
Positioning Device
A Global Positioning System (GPS) was used (C-Navigator World DGPS, GPS
72A) during monitoring to ensure the accurate recording of the position of the
monitoring vessel before taking measurements. The use of DGPS was used for positioning
device, which was well calibrated at an appropriate checkpoint.
Water Sampling Equipment
Water samples for suspended solids measurement were collected by the use
of a multi-bottle water sampling system (General Oceanics Inc., Rosette Sampler ROS02), consisting of PVC
bottles of more than two litres, which could be
effectively sealed with cups at both ends.
The water sampler had a positive latching system to keep it open and
prevent premature closure until released by a messenger when the sampler was at
the selected water depth.
3.3.2
Monitoring Methodology
Timing & Frequency
In-situ and SS data were collected daily at both
control and impact stations in the zone which was under monitoring provided
that the monitoring period had covered the mid-flood tide and/or mid-ebb
tide. The water quality sampling was undertaken within a 3 hour window of 1.5
hours before and 1.5 hours after mid-flood and mid-ebb tides. Tidal range for flood and ebb tides was
not less than 0.5 m for capturing representative tides.
Continuous In-situ
measurements were taken at 30- to 60- minute intervals (subject to the weather
conditions and travelling time between stations) for each impact station within
the zone subject to monitoring.
Reference was made to the predicted tides at Waglan
Island, which is the tidal station nearest to the Project site, published on
the website of Hong Kong Observatory([1]). Based on the predicted
water levels at
Duplicate samples were collected from each of the monitoring events for in
situ measurements and laboratory analysis.
Depths
Each station was sampled and measurements were taken at three depths, 1
m below the sea surface, mid depth and 1m above the sea bed.
Protocols
The multi-parameter measuring instrument (YSI 6820) was checked and
calibrated by an HOKLAS accredited laboratory before use. Onsite calibration was also carried out
to check the responses of sensors and electrodes using certified standard
solutions before each use.
Sufficient stocks of spare parts were maintained for replacements when
necessary, and backup monitoring equipment was made available.
Water samples for SS measurements were collected in high density
polythene bottles, packed in ice (cooled to 4° C without being frozen), and
delivered to an HOKLAS accredited laboratory as soon as possible after
collection.
Laboratory Analysis
All laboratory work was carried out by a HOKLAS accredited
laboratory. Water samples of about
1,000 mL were collected at the monitoring and control
stations for carrying out the laboratory determinations. The determination work started within
the next working day after collection of the water samples. The analyses followed the standard methods
as described in APHA Standard Methods for
the Examination of Water and Wastewater, 19th Edition, unless
otherwise specified (APHA 2540D for SS).
The QA/QC details were in accordance with requirements of HOKLAS or another
internationally accredited scheme (for details refer to Annex B).
3.3.3
Action and Limit Levels
The Action and Limit levels for Zones A
and E, which were established based on the results of Baseline Environmental Monitoring Part A, are presented in Tables 3.4.
Table 3.4 Action
and Limit Levels of Water Quality for Zones A and E
|
Parameter |
Action
Level |
Limit
Level |
|
Dissolved Oxygen (DO) (1) |
Surface and Mid-depth (2) |
Surface and Mid-depth (2) |
|
|
5%-ile
of baseline data for surface and middle layer = 6.59 mg L-1 |
1%-ile
of baseline data for bottom layer = 6.42 mg L-1 |
|
|
|
|
|
|
Bottom |
Bottom |
|
|
5%-ile
of baseline data for bottom layers = 6.58 mg L-1 |
1%-ile of baseline for bottom layer = 6.42 mg L-1 |
|
|
|
|
|
Depth-averaged Suspended Solids (SS) (3) (4) |
95%-ile of baseline data = 7.91 mg L-1 |
99%-ile of baseline data = 8.96 mg L-1 |
|
|
or 120% of control station's SS at the same
tide of the same day |
or 130%
of control station's SS at the same tide of the same day |
|
|
|
|
|
Depth-averaged Turbidity (Tby)
(3) (4) |
95%-ile of baseline data
= 5.17 NTU |
99%-ile of baseline data
= 5.72 NTU |
|
|
or 120% of control station's Tby at the same tide of the same day |
or 130% of control station's Tby at the same tide of the same day |
|
|
|
|
|
Notes: (1) For
DO, non-compliance of the water quality limits occurs when monitoring result
is lower than the limits. (2) The
Action and Limit Levels for DO for Surface & Middle layer were calculated
from the combined pool of baseline surface layer data and baseline middle
layer data. (3) “Depth-averaged”
is calculated by taking the arithmetic means of reading of all three depths. (4) For
turbidity and SS, non-compliance of the water quality limits occurs when
monitoring result is higher than the limits. |
||
The Action and Limit levels for Zones B to
D, which were established based on the results of Baseline Environmental Monitoring Part B. The Action and Limit Levels of DO and
turbidity are derived from the baseline monitoring data for all impact stations
for Zones B to D (including Stations F1, C1, C2 and C3), and the results are
presented in Table 3.5. Two sets of the Action and Limit levels
of suspended solids were established for two groups of impact monitoring
station(s) in the area, namely F1 to monitor the FCZ and C1, C2 as well as C3
to monitor the coral communities (see Table
3.6).
Table 3.5 Action
and Limit Levels of Dissolved Oxygen and Turbidity for Zones B to D
|
Parameter |
Action
Level |
Limit
Level |
|
Dissolved Oxygen (DO) (1) |
Surface and Mid-depth (2) |
Surface and Mid-depth (2) |
|
|
5%-ile
of baseline data for surface and middle layer = 7.22 mg L-1 |
1%-ile
of baseline data for bottom layer =7.12 mg L-1 |
|
|
|
|
|
|
Bottom |
Bottom |
|
|
5%-ile
of baseline data for bottom layers = 7.14 mg L-1 |
1%-ile of baseline for bottom layer = 7.05 mg L-1 |
|
|
|
|
|
Depth-averaged Turbidity (Tby)
(3) (4) |
95%-ile of baseline data
= 6.49 NTU |
99%-ile of baseline data
= 8.35 NTU |
|
|
or 120% of control station's Tby at the same tide of the same day |
or 130% of control station's Tby at the same tide of the same day |
|
|
|
|
|
Notes: (1) For
DO, non-compliance of the water quality limits occurs when monitoring result
is lower than the limits. (2) The
Action and Limit Levels for DO for Surface & Middle layer were calculated
from the combined pool of baseline surface layer data and baseline middle
layer data. (3) “Depth-averaged”
is calculated by taking the arithmetic means of reading of all three depths. (4) For
turbidity, non-compliance of the water quality limits occurs when monitoring
result is higher than the limits. |
||
Table 3.6 Action
and Limit Levels of Suspended Solids for Impact Stations F1, C1, C2, and C3
|
Parameter |
Action
Level |
Limit
Level |
|
Depth-averaged Suspended Solids (SS) |
Station F1 95%-ile of baseline data = 6.89 mg L-1 |
Station F1 99%-ile of baseline data = 7.11 mg L-1 |
|
|
Stations C1, C2 and C3 95%-ile of baseline data = 12.42 mg L-1 |
Stations C1, C2 and C3 99%-ile of baseline data = 14.28 mg L-1 |
|
|
|
|
|
|
or 120% of control station's SS at the same
tide of the same day |
or 130%
of control station's SS at the same tide of the same day |
|
|
|
|
|
Notes: (1) “Depth-averaged”
is calculated by taking the arithmetic means of reading of all three depths. (2) Non-compliance
of the water quality limits occurs when monitoring result is higher than the
limits. |
||
3.3.4
Event and Action Plan
The Event and Action Plan for water
quality monitoring which was stipulated in the EM&A Manual is presented in Table
3.7.
Table
3.7 Event
Action Plan for Water Quality
|
Event |
Contractor |
|
Action
Level Exceedance |
Step 1
- repeat sampling event. Step
2 – identify source(s) of impact
and confirm whether exceedance was due to the
construction works; Step
3 – inform EPD, AFCD and LCSD and
confirm notification of the non-compliance in writing; Step
4 - discuss with cable
installation contractor the most appropriate method of reducing suspended
solids during cable installation (e.g. reduce cable laying speed/volume of
water used during installation). Step
5 - repeat measurements after
implementation of mitigation for confirmation of compliance. Step
6 - if non compliance continues -
increase measures in Step 4 and repeat measurements in Step 5. If non compliance occurs a third time,
suspend cable laying operations. |
|
Limit Level Exceedance |
Undertake Steps 1-5 immediately, if further non compliance continues at the
Limit Level, suspend cable laying operations until an effective solution is
identified. |
A total of three monitoring
events were scheduled between 29 May and 4 June 2009.
All monitoring events at all designated monitoring stations were
performed on schedule, ie on 29 May, 30 May and 31
May 2009.
4.1
Data Collected
During Mid-Ebb and/or Mid-Flood Tidal Conditions
The monitoring data taken during the
mid-ebb and/or mid-flood tidal conditions are presented in Annex C and compared against the
baseline monitoring results in Figures C1
– C12. The impact monitoring
results, except DO, obtained during this week were mostly comparable to the
results recorded during the baseline monitoring. Similar to the results of the previous
week, dissolved oxygen levels at all the monitoring stations appeared to be fluctuating
and lower than the baseline data.
It should be noted that DO levels measured at all the impact stations
were of similar magnitude to DO levels detected at the control stations. This implies the background levels of DO
were also relatively low.
Depth-averaged turbidity and suspended
solids were generally compliant with the Action and Limit Levels with the
exception of 29 May 2009. A review
of the above exceedance is discussed in the following
section.
4.1.1
Exceedances
for Dissolved Oxygen from 29 May to 31 May 2009
Due to weather constraints, the working
vessel had been on a four point mooring in Zone A
awaiting safe conditions offshore to progress cable installation operations
since the afternoon of 23 May 2009.
No onboard or underwater construction activities had been carried out
during the period of 24 May and 29 May 2009. Neither the injector nor the thrusters
were in operation. However, daily exceedances of Limit Levels for dissolved oxygen were
recorded during the water quality monitoring in these six days.
It was concluded in the previous weekly
impact report that the recent declining trends of dissolved oxygen and daily DO
exceedances could be due to natural fluctuation (ie stratification followed by de-stratification) and such
situation may last for a certain period of time due to the unstable weather
conditions.
During the cable installation works
undertaken in Zones A to E between 30 May and 31 May 2009, exceedances
of Action and Limit Levels for dissolved oxygen continued to occur. Similarly, the DO concentrations
measured at all the impact stations were comparable to those recorded at the
control stations on 30 May and 31 May 2009. In addition, non-compliances of DO
levels were also noted at the control stations. This suggests the ambient DO levels were
relatively low and DO depletion was first detected in the bottom layer of the
water column on 22 May 2009 (see Annex C).
As seen in Figures D2 and D3 in Annex D, the concentrations of DO were
very stable and maintained at steady levels during the marine works on 30 May
and 31 May 2009. Furthermore, DO
concentrations measured before the commencement of the cable installation works
in Zone B were found to be lower than those recorded during and after the
marine works (Figure D3). Hence, the DO exceedances
could be a result of natural fluctuation in DO levels as discussed earlier.
Given no exceedances
of turbidity and SS were reported, there were no indications of the pollution
sources coming from the Project works area. The DO exceedances
were, therefore, considered unlikely related to the Project works.
It should be noted that although exceedances of the Action and Limit Levels for DO occurred,
no non-compliances of the WQOs (ie
not less than 2 mg/L for 90% of samples for bottom DO and not less than 4 mg/L
for 90% of samples for depth-averaged DO) were reported.
4.1.2
Exceedances
for Depth-averaged Turbidity and Suspended Solids on 29 May 2009
Exceedances of the Action and Limit Levels for
Depth-averaged Turbidity and Suspended Solids (SS) were recorded on 29 May 2009
(Table 4.1).
The Contractor confirmed that the
Networker was on a four point mooring in Zone A and no onboard or underwater
construction activities had been undertaken throughout the day of 29 May
2009. Neither the injector nor the
thrusters were in operation.
During the mid-flood tide in the morning,
the levels of turbidity and suspended solids measured at station B1 exceeded
the Limit Levels derived from the baseline data whilst these values were well
below 120% of the control station’s turbidity and SS, respectively. Turbidity and SS levels of station B1
did not show non-compliance during the following mid-ebb tide.
Exceedances of the Action and Limit Levels for SS
were noted at station S2 and S3 during the mid-ebb tide. The SS level measured at S3 was 0.2 mg/L
higher than the 120% of the control station’s SS but less than the Action Level
derived from the baseline data.
Similarly, the SS of S2 was 0.6 mg/L above the 130% of the control
station’s SS but did not exceed the Limit Level derived from the baseline
data. Although the turbidity level
of S2 was not in compliance with the Action and Limit Levels derived from the
baseline data, it did not exceed the 120% of turbidity recorded at the control
station R1. It is important to note
that turbidity and SS levels of stations S2 and S3 did not show non-compliances
during the preceding mid-flood tide.
It was, therefore, considered that the
turbidity and SS exceedances were more likely to be
caused by localised factors or temporary tidal influence rather than the
Project works.
Table
4.1 Exceedances of Action and Limit Levels for Depth-averaged
Turbidity and Suspended Solids on 29 May 2009
|
Exceedance
Log No. |
0096120_29
May 09_Turb_E_Station S2 0096120_29
May 09_Turb_F_Station B1 0096120_29
May 09_SS_E_Station S2 0096120_29
May 09_SS_F_Station B1 0096120_29
May 09_SS_E_Station S3 |
||
|
Sampling date |
29
May 2009 |
||
|
Monitoring station |
B1,
S2 and S3 |
||
|
Parameter |
Depth-averaged
Turbidity (NTU) Depth-averaged
Suspended Solids (SS, mg/L) |
||
|
Action Levels |
Mid-Ebb |
Turbidity :
120% of R1 = 8.9 or 5.17 (baseline data) SS
: 120% of R1 = 7.6 or 7.91 (baseline data) |
|
|
Mid-Flood |
Turbidity : 120%
of R1 = 6.8 or 5.17 (baseline data) SS : 120% of R1
= 9.6 or 7.91 (baseline data) |
||
|
Limit Levels |
Mid-Ebb |
Turbidity :
130% of R1 = 9.7 or 5.72 (baseline data) SS
: 130% of R1 = 8.2 or 8.96 (baseline data) |
|
|
Mid-Flood |
Turbidity : 130%
of R1 = 7.4 or 5.72 (baseline data) SS : 130% of R1
=10.4 or 8.96 (baseline data) |
||
|
Measured Levels at Station B1 |
Mid-Ebb |
Turbidity =
3.35 SS
= 4.5 |
|
|
Mid-Flood |
Turbidity =
5.97 SS = 9.5 |
(exceeds
Limit Level) (exceeds Limit
Level) |
|
|
Measured Levels at Station S2 |
Mid-Ebb |
Turbidity =
6.08 SS
= 8.8 |
(exceeds
Limit Level) (exceeds
Limit Level) |
|
Mid-Flood |
Turbidity = 4.4
SS = 5.2 |
|
|
|
Measured Levels at Station S3 |
Mid-Ebb |
Turbidity =
5.17 SS
= 7.8 |
(exceeds
Action Level) |
|
Mid-Flood |
Turbidity =
3.85 SS = 5.3 |
|
|
4.2
Continuous
In-Situ Measurement Data
Continuous in-situ measurements were taken at the impact monitoring stations within
the required monitoring zone at 30- to 60- minute intervals (subject to the
weather conditions and travelling time between stations) and the results and
the graphical presentations were included in Annex D.
In general, the water quality in the vicinity
of the Project works was stable and acceptable throughout each sampling day (ie 29 May, 30 May and 31 May 2009) with the exception of
some fluctuations in the turbidity levels.
5.1
Summary of
Environmental Exceedance
Daily Notification of Exceedances
(NOEs) with detailed investigation reports were
issued to EPD and AFCD during the monitoring period (ie
29 May to 31 May 2009) for recording water quality monitoring exceedances on dissolved oxygen, turbidity and suspended
solids of the monitoring stations.
The exceedances were examined against the
Project works. Results of the
detailed investigation indicated that none of the exceedances
were attributed to the Project construction works.
5.2
Summary of
Environmental Complaint
No complaints were received during the
reporting period.
5.3
Summary of
Environmental Summons and Prosecution
No summons or prosecution on environmental
matters were received during the reporting period.
6.1
Key Issues For
The Coming Month
As there will be no cable installation
works in the following weeks, the impact monitoring will be suspended and the
post-project monitoring will take place after the completion of the grout
mattress installation at the crossing of Tata’s cable system and HKE's gas pipeline in
south east
6.2
Monitoring
Schedule For The Coming Month
The post-project monitoring is tentatively
scheduled in early July 2009 subject to works progress and weather
constraints. The water sampling
will be conducted at the same monitoring location as in this reporting week.
This Weekly Impact Monitoring Report
presents the EM&A work undertaken during the period from 29 May to 4 June
2009 in accordance with the EM&A Manual and the requirements under FEP-01/294/2007.
Daily exceedances
of Action and Limit Levels for dissolved oxygen were recorded on the three
monitoring events (ie 29 May, 30 May and 31 May
2009). Depth-averaged turbidity and
suspended solids were generally compliant with the Action and Limit Levels with the exception of 29
May 2009. Results of the detailed
investigation indicated that none of the exceedances
were attributed to the Project construction works.
No complaints and
summons/prosecution were received during the reporting week.
The MT will keep track of the EM&A
programme to verify compliance of environmental requirements and the proper
implementation of all necessary mitigation measures.