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.
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
The weather and meteorological
conditions during the monitoring are provided in Appendix K.
4.8.4
Number of Action/ Limit
exceedance recorded in the reporting month at each impact stations is
summarized in Table 15.
4.8.5
During the reporting period, no
Action and Limit Level exceedance was recorded for water quality monitoring.
4.8.6
The Event and Action Plan for
water quality is given in Appendix H.
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).