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 |
2 |
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 summarised
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 |
0 |
0 |
0 |
0 |
|
Limit Level |
2 |
1 |
0 |
0 |
3 |
0 |
|
|
NTR-IS1 |
Action Level |
0 |
0 |
0 |
N/A |
0 |
0 |
|
Limit Level |
1 |
1 |
1 |
3 |
0 |
||
|
SHST-IS2 |
Action Level |
0 |
1 |
0 |
1 |
0 |
|
|
Limit Level |
2 |
1 |
1 |
4 |
0 |
||
|
MWR-IS3 |
Action Level |
0 |
0 |
0 |
0 |
0 |
|
|
Limit Level |
2 |
1 |
1 |
4 |
0 |
||
|
Total |
Action Level |
0 |
1 |
0 |
0 |
1 |
0 |
|
Limit Level |
7 |
4 |
3 |
0 |
14 |
0 |
* Exceedances record date: 19/04/2023, 21/04/2023
Seven
(7) Limit Level for DO, One (1) Action Level and Four
(4) Limit Level for turbidity, and Three (3) Limit Level for Suspended Solid of
impact water quality monitoring were recorded. Exceedances were recorded on 19
and 21 April 2023. After investigation,
the exceedance was considered due to the other external factors rather than the
contract works due to the following reasons:
1. No pollution
discharged was observed from land-based site area;
2. Water quality
mitigation measures at the nearby construction sites (Contract No. ND/2019/02
and ND/2019/04) were observed properly maintained including silt curtain were
deployed for the construction of cofferdam around the works area, and green
barriers with impervious sheeting to direct site runoff to water pump to the
treatment facilities etc.
3. Muddy water from
upstream was observed at Siu Hang San Tsuen. Contaminated water from upper
stream was observed at Ma Wat River.
4. Control Station’s DO
Value already exceed either the Action or Limit Levels
5. Heavy rainfall (16mm
to 21mm) was recorded before the water quality monitoring which led to
increased surface runoff and hence adverse water quality
5.38
Should
any non-compliance of the criteria occur, actions in accordance with the Event/Action
Plan in Appendix N shall be carried
out.