4.1.1
In accordance with the EM&A Manual, impact monitoring is conducted for
three days per week at mid-flood and mid-ebb with sampling and measurement at
the designated monitoring stations.
4.2.1
Equipment used for in-situ measurement and water sampling during impact
water quality monitoring is summarised in Table
12. The equipment is in compliance with the requirements set out in the
EM&A Manual. All in-situ monitoring instruments were calibrated by a
HOKLAS- accredited laboratory. Calibration of temperature, DO, salinity, pH and
turbidity is conducted in three-month interval. Calibration certificates for
the water quality monitoring equipment are attached in Appendix D.
4.3.1
All in-situ monitoring instruments shall be checked, calibrated and
certified by a laboratory accredited under HOKLAS before use and subsequently
re-calibrated at three monthly intervals throughout all stages of the water
quality monitoring programme. Responses of sensors and electrodes shall be checked
with certified standard solutions before each use. Wet bulb calibration for a
DO meter shall be carried out before measurement at each monitoring location.
4.3.2
Sufficient stocks of spare parts shall be maintained for replacements
when necessary. Backup monitoring equipment shall also be made available so
that monitoring is uninterrupted even when some equipment is under maintenance
or calibration etc.
The monitoring parameters
and frequency for both in-situ measurement and laboratory analysis are
summarised in Table 13.
4.5.1
The position of water monitoring station will be located by the Differential
Global Positioning System (DGPS) or equivalent. The water depth of water
monitoring station will be determined by the echo sounder affixed to the bottom
of the monitoring vessel or a portable echo sounder depth detector.
4.5.2
Once the location and water depth are confirmed, water samples shall be
collected at 3 depths (1m below the surface, mid-depth, and 1m above the
seabed) of the water column at each location, except where water depth is less
than 6m, the mid-depth will be omitted and if the water depth is less than 3m
only the mid-depth station will be monitored. Duplicate marine samples will be
collected in each sampling event. The water samples are decanted from the water
sampler into the water sample bottles. The bottles are labelled, tightly sealed,
placed into a cool-box and packed with ice ready for delivery to the
laboratory.
4.5.3
Two consecutive measurements of water quality data, including pH,
salinity, dissolved oxygen and turbidity will be recorded according to the
monitoring locations. Separate deployment of the monitoring instruments and
water samplers will be conducted for the consecutive measurements or samplings.
The monitoring location / position, time, water depth, sampling depth, tidal
stages, weather conditions, sea condition and any special phenomena or work
underway nearby shall also be recorded. If the difference in value between the
first and second measurement of DO or turbidity parameters is more than 25% of
the value of the first reading, the reading shall be discarded and further
readings should be taken.
4.6
Laboratory Measurement / Analysis
Background
4.6.1
Acumen Laboratory and Testing Limited (HOKLAS Reg: No.241) has been
appointed to conduct the laboratory measurement or analysis of water sample in
this project.
Quality Assurance / Quality
Control
4.6.2
The laboratory incorporates a variety of QA/QC monitoring programme into
their testing system. Where applicable or available, the quality of the
analysis will be monitored by conducting the following QC analysis:
For each batch of 20 samples:
·
A minimal of 1 laboratory method blank will be analyzed;
·
A minimal of 1 sample duplicate will be analyzed;
·
A minimal of 1 sample matrix spike will be analyzed.
4.7.1
In accordance with the EM&A Manual, water quality monitoring should
be carried out at 3 designated monitoring locations.
4.7.2
The coordinates of the monitoring location stated in the EM&A Manual
is summarised in Table 14 and the locations of the water quality monitoring
stations shown in Figure 4.
4.8.1
The schedule of water quality monitoring in reporting month is provided
in Appendix E.
4.8.2
Impact water quality monitoring was conducted at all designated
monitoring stations in the reporting month. Impact water quality monitoring
results and graphical presentations are provided in Appendix F.
4.8.3
Typhoon Signal No. 8 was
hoisted on 1 September 2023. Due to safety concerns, the water quality
monitoring on 1 September 2023 has been cancelled.
4.8.4
Black Rainstorm Signal was
hoisted on 8 September 2023. Due to safety concerns, the water quality
monitoring on 8 September 2023 has been cancelled.
4.8.5
The weather and meteorological conditions during the monitoring are
provided in Appendix K.
4.8.6
Number of Action/ Limit exceedance recorded in the reporting month at
each impact stations is summarized in Table
15.
4.8.7
During the reporting period, no Action and Limit Level exceedance was
recorded for water quality monitoring.
4.8.8
The Event and Action Plan for water quality is given in Appendix H.
4.9
WetSeps
Three WetSeps
are deployed within the site for treatment of the site runoff prior to disposal
in compliance with the conditions stipulated in the water discharge license
(Variation of WPCO Discharge Licence was approved by EPD on 1 December 2022
with immediate effect).