5.1
In
accordance with the Updated EM&A Manual, impact water quality monitoring
shall be carried out three days per week at all the designated monitoring stations
during the construction period. The measurement periods are during the
construction of channel specified in Table 4.1 of the Updated EM&A Manual. The
interval between two sets of monitoring shall not be less than 36 hours.
5.2
Replicate
in-situ measurements of Dissolved Oxygen (DO), temperature, turbidity, pH,
Suspended Solids (SS) and samples for Suspended Solids (SS), ammonia nitrogen,
unionized ammonia, nitrate nitrogen and orthophosphate from each independent
sampling event were collected to ensure a robust
statistically interpretable database.
5.3
Appendix B shows the established Action
and Limit Levels for the water quality monitoring work according to the Updated EM&A Manual and
Baseline Water Quality Monitoring Report (KTN & FLN NDA).
5.4
Table 5.1
summarises
the monitoring parameters, monitoring periods and frequencies of the water
quality monitoring.
Table 5.1 Water
Quality Monitoring Parameters and Frequency
|
Parameters, unit |
Depth |
Frequency |
|
·
Temperature(°C) ·
pH(pH unit) ·
turbidity (NTU) ·
water depth (m) ·
salinity (ppt) ·
DO (mg/L and % of saturation) ·
SS (mg/L) ·
Ammonia Nitrogen (NH3-N)
(mg NH3-N/L) ·
Unionized Ammonia (UIA) (mg/L) ·
Nitrate-nitrogen (NO3-N)
(mg NO3--N/L) ·
Ortho-phosphate (PO4)
(mg PO43--P/L) |
·
3 water depths: 1m below
water surface, mid-depth and 1m above river bed. ·
If the water depth was less than 3m, mid-depth
sampling only. ·
If water depth was less than 6m, mid-depth may be
omitted. |
3 days per week during construction of channel |
5.5
According to Section
5.6.1.2 of the approved EIA Report,
the potential water quality impact during construction is due to the
alternation of natural streams (i.e. channelization of Ma Tso Lung Stream and Siu
Hang San Tsuen Stream) as these two streams are the ecologically important streams.
5.6
No construction of
channel was carried out at Ma Tso Lung Stream and Siu Hang San Tsuen Stream
during the reporting month. Therefore, no water quality monitoring was conducted.
Additional Water Quality Monitoring
5.7
Additional Water
Quality Monitoring shall be carried out at River Beas, River Indus and near Siu
Hang San Tsuen Stream three days per week at all designated monitoring stations
during the construction period. The measurement period are during the
construction site drainage along River Beas, construction of footbridge across
River Beas and during construction of bridge across River Indus.
5.8
Replicate in-situ
measurement and samples from each independent sampling event were collected to
ensure a robust statistically interpretable database. DO, temperature,
turbidity and pH were measured in-situ whereas SS and arsenic were determined
by an accredited laboratory. Other relevant data, including monitoring location
/ position, time, water depth, weather conditions and any special phenomena or
work underway at the construction site were recorded.
5.9
For all the
monitoring stations, sampling were taken at 3 water depths, namely 1m below the
water surface, mid depth and 1m above the river bed. For stations that were less than 3m in
depth, only the mid depth sample was taken. Should the water depth was less than 6m, in
which case the mid-depth station may have been omitted. The
interval between two sampling surveys was not less than 36 hours.
5.10 Appendix
B shows the established Action and
Limit Levels for the environmental monitoring works.
5.11 Additional impact water quality monitoring was conducted
at 6 monitoring stations (SYR-CS1, SYR-IS1, NTR-CS1, NTR-IS1, SHST-IS2,
MWR-IS3) which are summarised in Table
5.2. The location of monitoring stations is shown in Figures 5 and 6.
Table
5.2 Additional
Water Quality Monitoring Stations
|
Station |
Description |
Locations |
Measurement
Periods |
|
River Beas |
|||
|
SYR-CS1 |
Control Station |
Upstream of river |
During the construction site drainage along River
Beas and construction of the footbridge across River Beas |
|
SYR-IS1 |
Impact Station |
Downstream of
river |
|
|
River Indus and near Siu Hang San Tsuen Stream |
|||
|
NTR-CS1 |
Control Station |
Upstream of river |
During
construction of the
bridge across River Indus |
|
NTR-IS1 |
Impact Station |
Downstream of river |
|
|
SHST-IS2 |
Impact Station |
Water sensitive receiver at near Siu Hang San Tsuen
Stream |
|
|
MWR-IS3 |
Impact Station |
Water sensitive receiver at near
Ma Wat River |
|
5.12
Multi-parameter meters (Model YSI EXO) were used to measure DO, turbidity, salinity, pH
and temperature.
Dissolved
Oxygen (DO) and Temperature Measuring Equipment
5.13 The instrument for measuring dissolved oxygen and
temperature should be portable and weatherproof complete with cable, sensor, and
use DC power source. The equipment was capable of measuring:
·
A dissolved
oxygen level in the range of 0-20mg/L and 0-200% saturation; and
·
The temperature
within 0-45 degree Celsius.
5.14 The equipment had a membrane electrode with
automatic temperature compensation complete with a cable.
5.15 Sufficient stocks of spare electrodes and cables
were available for replacement where necessary.
5.16 Salinity compensation was built-in in the DO
equipment. In-situ salinity was
measured to calibrate the DO equipment prior to each DO measurement.
5.17 Turbidity was measured in situ by using the
nephelometric method. The instrument was portable and weatherproof using a DC
power sources complete with cable, sensor and comprehensive operation manuals.
The equipment was capable of measuring turbidity between 0-1000 NTU. The probe
cable was not less than 25m in length. The meter was calibrated in order to
establish the relationship between NTU units and the levels of Suspended
Solids.
5.18 A portable salinometer capable of recording
salinity within the range of 0-40 parts per thousand (ppt) was used for
salinity measurement.
5.19 A portable, battery-operated and hand held echo
sounder was used for the determination of water depth at each designated
monitoring station.
pH
5.20 The instrument consisted of a potentiometer, a
glass electrode, a reference electrode and a temperature-compensating device.
It was readable to 0.1pH in a range of 0 to 14. Standard buffer solutions of at
least pH 7 and pH 10 were used for calibration of the instrument before and
after use.
Water Sampling
for Laboratory Analysis
5.21
A water sampler, consisting of a
transparent Polyvinyl Chloride (PVC) of a capacity of not less than two litres which
can be effectively sealed with cups at both ends was used. 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.
In addition, a sampling cup attached to a fixed or extendable rod was also used
for sampling at the monitoring stations with swallow water.
Sample Container and Storage
5.22
Following collection, water samples for
laboratory analysis were stored in high density polyethylene bottles with
appropriate preservatives added, packed in the ice (cooled to 4oC
without being frozen). The samples were
delivered to WELLAB Limited (HOKLAS Registration No. HOKLAS083)
and analysed as soon as possible after collection of the water samples. Sufficient
volume of samples was collected to achieve the detection limit.
Calibration of
In Situ Instruments
5.23
The pH meter, DO meter and turbidimeter
were checked and calibrated before use. DO meter and turbidimeter were
certified by WELLAB Limited before use and subsequently re-calibrated at
quarterly basis throughout all stage of water quality monitoring programme.
Response of sensors and electrodes were checked with certified standard
solutions before each use. Wet bulb calibration for a DO meter was carried out
before measurement at each monitoring station.
5.24
For on-site calibration of field equipment
(Multi-parameter Water Quality System), the standard BS 1427:2009 “Guide to on-site test methods for
analysis of waters” was observed.
Back-up Equipment
5.25
Sufficient stocks of spare parts were
maintained for replacements when necessary. Backup monitoring equipment was
also be made available so that monitoring could
proceed uninterrupted even when some equipment was under
maintenance, calibration, etc.
5.26
Table
5.3
summarises the equipment used in the water quality
monitoring programme. Copies of the calibration certificates of the multi-parameter water quality systems are shown in Appendix C.
Table 5.3 Water
Quality Monitoring Equipment
|
Equipment |
Model and Make |
Qty. |
|
Water sampler and sampling cup |
A 2-Litre transparent PVC cylinder with latex cups at
both ends and sampling cup for monitoring stations with swallow water |
1 |
|
Sonar Water Depth Detector |
Garmin Striker plus 4 |
1 |
|
Multi-parameter Water Quality System |
YSI EXO 1 |
3 |
5.27
Table
5.4 summarises the monitoring parameters and
frequencies of the additional water quality monitoring. The water quality
monitoring schedule for the reporting month is shown in Appendix D.
Table
5.4 Additional
Water Quality Monitoring Parameters and Frequency
|
Monitoring Station(s) |
Parameters, unit |
Depth |
Frequency |
|
|
River Beas |
SYR-CS1 SYR-IS1 |
·
Temperature (oC) ·
pH (pH unit) ·
Turbidity (NTU) ·
Water depth (m) ·
Salinity (ppt) ·
Dissolved Oxygen
(DO) (mg/L and % of saturation) ·
Suspended Solids
(SS) (mg/L) ·
Arsenic (As)
(µg/L) |
·
3 water depths:
1m below water surface, mid-depth and 1m above river bed. ·
If the water
depth was less than 3m, mid-depth sampling only. ·
If water depth
was less than 6m, mid-depth might be omitted. |
3 days per week |
|
River Indus and near Siu
Hang San Tsuen Stream |
NTR-CS1 NTR-IS1 SHST-IS2 MWR-IS3 |
·
Temperature (oC) ·
pH (pH unit) ·
Turbidity (NTU) ·
Water depth (m) ·
Salinity (ppt) ·
Dissolved Oxygen
(DO) (mg/L and % of saturation) ·
Suspended Solids
(SS) (mg/L) |
||
5.28
Monitoring location and position, time,
sampling depth, weather conditions and any special phenomena or work underway
nearby was also recorded.
Instrumentation
5.29
Multi-parameter
meters (Model YSI EXO) were used to
measure DO, turbidity, salinity, pH and temperature.
Operating/Analytical
Procedures
5.30
At each measurement, two consecutive
measurements of DO concentration, DO saturation, salinity, turbidity, pH and
temperature were taken. The probes were retrieved out of the water after the
first measurement and then re-deployed for the second measurement. Where the
difference in the value between the first and second readings of each set was
more than 25% of the value of the first reading, the reading was discarded and
further readings were taken.
Laboratory
Analytical Methods
5.31
Duplicate samples from each independent
sampling event were required for
all parameters. Analysis of suspended solids and arsenic
were carried out by WELLAB Ltd. and comprehensive quality assurance and control
procedures were in place in order to ensure the quality
and consistency in results. The analysis
methods and limits of reporting are provided in Table 5.5.
Table 5.5 Method
for Laboratory Analysis for Water Samples
|
Determinant |
Proposed
Method |
Limit
of Reporting |
|
Total Suspend Solids (SS) |
APHA 17ed 2540 D |
2.5 mg/L |
|
Arsenic (As) |
In-house method SOP022 (ICP-AES) and SOP076 (ICP-MS) |
1 µg/L |
5.32
Water sampling equipment used during the
course of the monitoring process was decontaminated by manual washing and
rinsed with distilled water after each sampling event. All of the disposal
equipment was discarded after the sampling.
Sampling
Management and Supervision
5.33
All sampling bottles were labelled with
the sample I.D. (including
sampling station), laboratory number and sampling date. Water samples were
dispatched to the testing laboratory for analysis as soon as possible. All the
collected samples were stored in a cool box to keep the temperature less than 4oC
but without frozen. All water samples were handled under chain of custody
protocols and relinquished to the laboratory representatives at locations
specified by the laboratory.
Quality Control
Measures for Sample Testing
5.34
The samples testing and following QC
programmes were performed by WELLAB Ltd. for every batch of
20 samples:
·
One method blank; and
·
One set of QC sample.
5.35
All additional water quality monitoring
was conducted as scheduled in the reporting month. The water quality monitoring
schedule for this reporting month is shown in Appendix D.
5.36
The monitoring results and graphical
presentation of additional water quality monitoring are shown in Appendix G.
5.37 The summary of exceedance
record in the reporting month is shown in Appendix
O and summarized in the Table 5.6.
Table
5.6 Summary
of Water Quality Exceedances
|
Station |
Exceedance Level |
DO |
Turbidity |
SS |
Arsenic |
Total number of
Non-project Related Exceedances |
Total number of
project Related Exceedances |
|
SYR-IS1 |
Action Level |
0 |
0 |
1 |
1 |
2 |
0 |
|
Limit Level |
1 |
1 |
0 |
0 |
2 |
0 |
|
|
NTR-IS1 |
Action Level |
0 |
0 |
0 |
N/A |
0 |
0 |
|
Limit Level |
0 |
1 |
0 |
1 |
0 |
||
|
SHST-IS2 |
Action Level |
0 |
0 |
0 |
0 |
0 |
|
|
Limit Level |
0 |
1 |
1 |
2 |
0 |
||
|
MWR-IS3 |
Action Level |
0 |
1 |
0 |
1 |
0 |
|
|
Limit Level |
1 |
0 |
0 |
1 |
0 |
||
|
Total |
Action Level |
0 |
1 |
1 |
1 |
3 |
0 |
|
Limit Level |
2 |
3 |
1 |
0 |
6 |
0 |
* Exceedances record date: 30/09/2022
5.38 Two (2) Limit
Level for DO, One (1) Action Level for Arsenic, One (1) Action Level and One (1) Limit Level for Suspended
Solids, One (1) Action Level and Three (3) Limit Level for Turbidity of impact
water quality monitoring were recorded. Exceedances were recorded on 30
September 2022. After investigation, all exceedances were considered due to the
other external factors rather than the contract works due to the following
reasons:
1.
No pollution
discharge from site area was observed.
2.
Water from upstream
of Ng Tung River, Siu Hang San Tsuen River and Ma Wat River which outside the
project site boundaries were observed muddy and may led to the increase of
turbidity and SS level in the water body. Organic material is anticipated in
adverse water quality causing reduction in DO levels due to composition of
organic matter by microorganisms.
3.
Influx of muddy
water from Shenzhen River outside the project boundary to River Beas was
observed during sampling. It may cause Arsenic Level Exceedance.
4.
Water quality mitigation
measures at the nearby construction site (i.e. Contract No. ND/2019/02 and
ND/2019/04) were observed properly maintained including silt curtain, green
barriers with impervious sheeting to direct site runoff to water pump to the
treatment facilities and hydro-seeding surrounding the works etc.
5.
Heavy rainfall in
Northern District was recorded before and during the water quality monitoring
which led to increased surface runoff and hence adverse water quality.
5.39
Should
any non-compliance of the criteria occur, actions in accordance with the Event/Action
Plan in Appendix N shall be carried
out.