Contents
1.1 Background
1.2 Purpose
of this Report
1.3 Structure
of the Report
2.1 Monitoring
Location
2.2 Sampling
and Testing Methodology
2.3 Baseline
Monitoring Results
2.4 Action
and Limit Levels
ANNEXES
|
Annex A |
|
|
Annex B |
|
|
Annex C |
|
|
Annex D |
Baseline
Water Quality Monitoring
Baseline
water quality monitoring has been conducted between 17 September 2012 and 21
September 2012 at 12 designated monitoring stations (including 8 Sensitive
Receiver Stations, 3 Gradient Stations and 1 Control Station) established for the Project. In
situ water quality measurements and water samples were taken at the
monitoring stations on three occasions (days), at three depths (surface, middle
and bottom) where practical. The
intervals between two sets of monitoring were not less than 36 hours. The
water quality sampling was undertaken within a 4 hour window of 2 hour before
and 2 hour after mid flood and mid-ebb tides. The tidal range selected for the baseline monitoring
was at least 0.5 m for both flood and ebb tides as far as practicable.
No major activities influencing water quality were
observed in the vicinity of the Project’s marine works area during the baseline
monitoring. Water quality
monitoring results are, therefore, considered to be representative for the
baseline conditions of the areas where marine works will be undertaken for the
Project.
In accordance with the EM&A Manual, the baseline monitoring results were used to
determine the Action and Limit Levels for Dissolved Oxygen (DO), Suspended
Solids (SS) and Turbidity for the impact water quality monitoring which will be
conducted during marine works of the Project. The Action
and Limit Levels are summarized in Table 1
below.
Table
1 Action
and Limit Levels for Water Quality
|
Parameter |
Action Level |
Limit Level |
|
SS
in mgL-1 (Depth-averaged)
(a) (c) |
95%-ile
of baseline data (4.09 mg L-1),
or |
99%-ile
of baseline data (4.60 mg L-1) ,
and |
|
20% exceedance
of value at any impact station compared with corresponding data from control
station |
30% exceedance
of value at any impact station compared with corresponding data from control station |
|
|
DO
in mgL-1 (b) |
Surface and Middle(d) 5%-ile
of baseline data for surface and middle layer (4.72 mg L-1) |
Surface and Middle(d) 5mg/L or 1%-ile of baseline for surface and middle layer (4.57 mg L-1) |
|
Bottom 5%-ile of baseline data for bottom
layers (4.52 mg L-1) |
Bottom 2mg/L or 1%-ile of baseline data for
bottom layer (4.44 mg L-1) |
|
|
Turbidity
in NTU (Depth-averaged) (a) (c) |
95%-ile
of baseline data (3.01 NTU), or |
99%-ile
of baseline data (3.13 NTU), and |
|
20% exceedance
of value at any impact station compared with corresponding data from control
station |
30% exceedance
of value at any impact station compared with corresponding data from control station |
|
|
Notes: a.
“Depth-averaged” is calculated by taking
the arithmetic means of reading of all sampled depths. b.
For DO, non-compliance of the water quality
limits occurs when the monitoring result is lower than the limits. c.
For SS and turbidity, non-compliance of the
water quality limits occurs when monitoring result is higher than the limits. d.
The Action and Limit Level for DO for
surface and middle layer were calculated from the combined pool of baseline
surface layer data and baseline middle layer data. |
||
NTT
Com Asia (NTTCA) proposes to install a telecommunication cable (Asia
Submarine-cable Express (ASE) cable) of approximately 7,200 km in length,
connecting
A
Project Profile (PP-452/2011) which includes an assessment of the potential
environmental impacts associated with the installation of the submarine
telecommunications cable system 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 the application for Permission to apply
directly for Environmental Permit (EP).
The Environmental Protection Department, subsequently issued an Environmental
Permit (EP- 433/2011).
Pursuant
to Condition 2.4 of the EP, an environmental monitoring and
audit (EM&A) programme as set out in the Environmental Monitoring and Audit Manual (M&A Manual) is
required to be implemented. In
accordance with the EM&A Manual,
baseline monitoring of marine water quality should be undertaken for the
Project. This Water Quality Baseline Monitoring Report (“the Report”) is prepared
by ERM-Hong Kong, Limited (ERM) on behalf of NTT Com Asia (NTTCA) to present
the methodology and findings of the baseline marine water quality monitoring for
the Project.
Given that the water
sampling stations in Zone B are situated quite far away from those in Zones A and
C, and the commencement dates of construction in each zone are also different,
it is recommended to present the baseline data in separate reports (i.e. Part A
for Zone A, Part B for Zone B and Part C for Zone C) and the corresponding
Action and Limit Levels will be derived from the baseline data for each zone.
The
purpose of this Baseline Water Quality Monitoring
Report (Part B) is to determine the baseline marine water quality at the
designated monitoring locations around the Project works area in Zone B prior
to the commencement of the cable laying works of the Project. Such baseline conditions will be used as
the basis for assessing water quality impacts, if any, and for compliance
monitoring during the construction of the Project.
Under
the requirement of Condition 2.4 of
the EP, the baseline monitoring report on water
quality shall be prepared and submitted to the DEP no later than two
weeks before the commencement of construction works of the Project.
The
remainder of the report is structured as follows:
Section
1: Introduction
Provide details of the background,
purpose and structure of the report.
Section
2: Water Quality Monitoring
Summarize the water quality
monitoring locations and frequency, monitoring methodology and baseline
monitoring results, and establishes the Action and Limit Levels in accordance
with the EM&A Manual.
Section
3: Conclusion
Conclude the representativeness
of the baseline monitoring results and observations for the Project.
Baseline
water quality monitoring in Zone B was conducted prior to the commencement of cable
laying works at the monitoring stations listed in
Table 2.1 and
shown in Figure 2.1.
·
B1
is an Impact Station to monitor the impacts of cable installation works on the
·
B2
is an Impact Station to monitor the impacts of cable installation works on the
·
B3
is an Impact Station to monitor the impacts of cable installation works on the
Shek O Beach;
·
E1
is an Impact Station to monitor impacts of cable installation works on
·
E2
is an Impact Station to monitor the impacts of cable installation works on the
coral communities at Tung Lung Chau;
·
E6
is an Impact Station to monitor the impacts of cable installation works on the
coral communities at Tai Long Pai (the Gradient
Station is not set due to the short distance of this Impact Station to nearby
proposed cable works which may affect the cable laying works);
·
E9
is an Impact Station to monitor the impacts of cable installation works on the
coral communities at Cape Collison (the Gradient
Station is not set due to the short distance of this Impact Station to nearby
proposed cable works which may affect the cable laying works);
·
F1
is an Impact Station to monitor the impacts of cable installation works on the
Tung Lung Chau Fish Culture Zone;
·
G3
is a Gradient Station between F1 and the cable alignment;
·
G4
is a Gradient Station between E2 and the cable alignment;
·
G7
is a Gradient Station between E1 and the cable alignment; and
·
C2
is a Control Station (approximately 3.4 km from the proposed cable alignment)
for Zone B. It is not supposed to
be influenced by the cable laying works due to its remoteness to the
construction works.
Table 2.1 Water
Quality Monitoring Stations
|
Monitoring Station |
Nature |
Easting |
Northing |
|
B1 |
Impact Station (Beach) |
843557 |
811853 |
|
B2 |
Impact Station (Beach) |
844062 |
810369 |
|
B3 |
Impact Station (Beach) |
843988 |
809902 |
|
E1 |
Impact
Station (Marine Reserve) |
845474 |
810605 |
|
E2 |
Impact
Station (Coral Communities) |
845203 |
815205 |
|
E6 |
Impact
Station (Coral Communities) |
845321 |
816718 |
|
E9 |
Impact
Station (Coral Communities) |
843557 |
811853 |
|
F1 |
Impact Station
(Fish Culture Zone) |
847196 |
811056 |
|
G3 |
Gradient Station |
846099 |
812826 |
|
G4 |
Gradient Station |
846583 |
810809 |
|
G7 |
Gradient Station |
845946 |
808583 |
|
C2 |
Control Station |
849603 |
811528 |
The
parameters measured in situ were:
·
Dissolved Oxygen (DO) (% saturation and mg L-1)
·
Salinity (ppt)
·
Temperature
(ºC)
·
Turbidity
(NTU)
The
only parameter to be measured in the laboratory was:
·
Suspended solids (SS) (mg L-1)
In addition to the water
quality parameters, other relevant data were also measured and recorded in
field logs, including the location of the sampling stations, water depth, time,
weather conditions, sea conditions, tidal state, current direction and speed,
special phenomena and work activities undertaken around the monitoring and
works area that may influence the monitoring results.
Table 2.2
summaries the equipment used for the baseline water quality monitoring.
Table
2.2 Equipment used during the
Baseline Water Quality Monitoring Programme
|
Equipment |
Model |
|
Global
Positioning Device |
Garmin etrex
10 |
|
Water Depth Gauge |
Speedtech
Instrument SM-5A |
|
Water Sampling
Equipment |
1510
Kemmerer Water Sampler |
|
Salinity,
DO, Temperature Measuring Meter |
YSI Pro 2030 |
|
Current
Velocity and Direction |
Flow Probe
FP11 |
|
Turbidity
Meter |
HACH Model
2100Q Turbid Meter |
The
water monitoring was carried out on three occasions (days) and the intervals
between two sets of monitoring were not less than 36 hours. The water quality sampling was
undertaken within a 4 hour window of 2 hour before and 2 hour after mid flood
and mid-ebb tides. The
tidal range selected for the baseline monitoring was at least 0.5 m for both
flood and ebb tides as far as practicable.
Reference
were made to the predicted tides at Tai Miu Wan, which is the tidal station
nearest to the Project Site, published on the website of the Hong Kong
Observatory ([1]). Based on the predicted tidal levels at
Tai Miu Wan, the baseline water quality monitoring was conducted between 17
September 2012 and 21 September 2012, following the schedule presented in Annex A.
Schedule for baseline monitoring has been submitted to the Contractor,
Independent Environmental Checker (IEC), Engineer Representative (ER) and
Environmental Protection Department (EPD) one week prior to the commencement of
the monitoring works.
All
in situ monitoring instruments were
checked, calibrated and certified by a laboratory accredited under HOKLAS or
any other international accreditation scheme before use (see calibration
reports in Annex B), and subsequently re-calibrated at-monthly intervals
throughout all stages of the water quality monitoring. Responses of sensors and electrodes were
checked with certified standard solutions before each use.
For
the on-site calibration of field equipment, the BS 1427: 1993, Guide to Field and On-Site Test Methods for the Analysis
of Waters was observed. Sufficient
stocks of spare parts were maintained for replacements when necessary. 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 a HOKLAS
laboratory as soon as possible after collection.
Two
replicate samples were collected from each of the monitoring events for in situ measurement and lab analysis.
All laboratory work was
carried out in 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 SS laboratory
measurements were provided within 2 days of the sampling event (48 hours). 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 (Annex C)
Each
station was sampled and measurements/ water samples were taken at three depths,
namely, 1 m below water surface, mid-depth and 1 m above sea bed, except where
the water depth less than 6 m, the mid-depth station may be omitted. For stations that are less than 3 m in
depth, only the mid-depth sample was taken.
For
in situ measurements, duplicate
readings were made at each water depth at each station. Duplicate water samples were collected
at each water depth at each station.
The
monitoring data and graphical presentations for baseline water quality
monitoring are provided in Annex D. No marine construction activities were
observed in the vicinity of the monitoring stations during the baseline
monitoring. No other major activities
influencing water quality were identified during the monitoring period, and weather
conditions were generally calm during the baseline monitoring period.
The
observations from the monitoring results are as following:
·
For all monitoring stations, water quality was
variable throughout the baseline monitoring period and this represented natural
fluctuation in water quality ;
·
Fluctuation of Dissolved Oxygen (DO) was observed during
mid-flood, whilst DO levels fluctuated within a limited range. Hence, it is considered that DO levels
between Sensitive Receivers and Control Stations are similar in average although
fluctuation exists;
·
DO levels at all depths were generally high for all
samples, DO levels <4 mg L-1 were not recorded;
·
Relatively higher levels of turbidity were recorded at
Sensitive Receiver Station E9 during mid-ebb and mid-flood tidal condition;
·
Higher levels of suspended solids (SS) were recorded
at Sensitive Receiver Station E9 during both mid-ebb and mid-flood; and
·
The above sporadic patterns of relatively high levels
of turbidity and SS at the water monitoring stations are considered to be a
characteristic of water quality in this area of Hong Kong.
The
Action and Limit Levels were set in the EM&A
Manual and the proposed Action and Limit Levels were determined as shown in
Table 2.3.
Table 2.3 Determination of Action
and Limit Levels for Water Quality
|
Parameter |
Action Level |
Limit Level(d) |
|
SS in mgL-1 (Depth-averaged)
(a) (c) |
95%-ile of baseline data or |
99%-ile of baseline data, and |
|
20% exceedance of value at
any impact station compared with corresponding data from control station |
30% exceedance of value at
any impact station compared with corresponding data from control station |
|
|
DO in mgL-1
(b) |
Surface and Middle 5%-ile of baseline data for
surface and middle layer |
Surface and Middle 5mg/L or 1%-ile of baseline
for surface and middle layer |
|
Bottom 5%-ile of baseline data for bottom layers |
Bottom 2mg/L
or 1%-ile of baseline data for bottom layer |
|
|
Turbidity
in NTU (Depth-averaged) (a) (c) |
95%-ile of baseline data, or |
99%-ile of baseline data, and |
|
20% exceedance of value at
any impact station compared with corresponding data from control station |
30% exceedance of value at
any impact station compared with corresponding data from control station |
|
|
Notes: a. “Depth-averaged”
is calculated by taking the arithmetic means of reading of all sampled
depths. b. For DO,
non-compliance of the water quality limits occurs when the monitoring result
is lower than the limits. c. For SS
and turbidity, non-compliance of the water quality limits occurs when
monitoring result is higher than the limits. d. Limit
level for DO was derived from the Water Quality Objectives (WQO) for Junk
Bay, Eastern Buffer, and Mirs
Bay Water Control Zones under the Water Pollution Control Ordinance (WPCO) Chapters 358L, 358Y, and
358I respectively. |
||
The
Action and Limit Levels have been determined based on baseline water quality monitoring
data for all monitoring stations in Zone B. The results are presented in Table 2.4. Please note that the results are used to
determine the Action and Limit Levels for the cable laying works to be
undertaken in Zone B.
Table 2.4 Action
and Limit Levels for Water Quality
|
Parameter |
Action Level |
Limit Level |
|
SS in mgL-1 (Depth-averaged)
(a) (c) |
95%-ile of baseline data (4.09 mg L-1), or |
99%-ile of baseline data (4.60 mg L-1) , and |
|
20% exceedance of value at any impact station compared
with corresponding data from control station |
30% exceedance of value at any impact station compared
with corresponding data from
control station |
|
|
DO in mgL-1
(b) |
Surface and Middle(d) 5%-ile of baseline data for surface and middle layer (4.72 mg L-1) |
Surface and Middle(d) 5mg/L or 1%-ile of baseline for surface and middle
layer (4.57 mg L-1) |
|
Bottom 5%-ile
of baseline data for bottom layers (4.52 mg L-1) |
Bottom 2mg/L
or 1%-ile of baseline data for bottom layer (4.44 mg L-1) |
|
|
Turbidity
in NTU (Depth-averaged) (a) (c) |
95%-ile of baseline data (3.01 NTU), or |
99%-ile of baseline data (3.13 NTU), and |
|
20% exceedance of value at any impact station compared
with corresponding data from control station |
30% exceedance of value at any impact station compared
with corresponding data from
control station |
|
|
Notes: e. “Depth-averaged”
is calculated by taking the arithmetic means of reading of all sampled
depths. f. For DO,
non-compliance of the water quality limits occurs when the monitoring result
is lower than the limits. g. For SS
and turbidity, non-compliance of the water quality limits occurs when
monitoring result is higher than the limits. h. The
Action and Limit Level for DO for surface and middle layer were calculated
from the combined pool of baseline surface layer data and baseline middle
layer data. |
||
Baseline water quality
monitoring in Zone B has been conducted between 17 September 2012 and 21
September 2012 at 12 designated monitoring stations (including 8 Sensitive
Receiver Stations, 3 Gradient Stations and 1 Control Station). The monitoring was conducted in 3 days,
at mid-flood and mid-ebb tides, at three depths (surface, middle and
bottom). The intervals
between two sets of monitoring were not less than 36 hours. During the monitoring period, no major
activities influencing water quality were observed in the vicinity of the
Project’s marine works area. Water
quality monitoring results are, therefore, considered to be representative of
the baseline conditions of the areas where marine works will be undertaken for
the Project.
The baseline monitoring
results were used to determine the Action and Limit Levels for the DO, SS and
turbidity for impact monitoring to be conducted at Zone B throughout the
construction phase of the Project.