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 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 shall be 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 pre-construction ET’s Updated
EM&A Manual and Baseline Water Quality Monitoring Report (KTN & FLN
NDA).
5.4
Table 5.1 summarized 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 the Section 5.6.1.2 of 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
ecological importance 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 were recorded, including monitoring location / position, time,
water depth, weather conditions and any special phenomena or work underway at
the construction site.
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 are less than
3m in depth, only the mid depth sample was taken. Should the water depth is less than 6m, in which case the mid-depth station may be
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 is summarised in Table 5.2. The location of monitoring
stations are shown in Figure 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
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 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
A multi-parameter meters (Model YSI EXO) was
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 was consisting 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 sample were delivered to WELLAB Limited (HOKLAS
Registration No.083) 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 the on-site calibration of field equipment
(Multi-parameter Water Quality System), the 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 can proceed uninterrupted even when
some equipment is under maintenance, calibration, etc.
5.26
Table 5.3
summarizes the equipment used in the water quality monitoring program. The
copies of the calibration certificates of multi-parameter water quality system
are shown in the 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
summarizes
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, for 2 weeks prior to the
commencement of
construction works |
|
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 be recorded.
Instrumentation
5.29
A multi-parameter meters (Model YSI EXO) was
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 are required for all parameter. Analysis of suspended solids and
arsenic were carried out by WELLAB Ltd. and comprehensive quality assurance and
control procedures in place in order to ensure the quality and consistency in
results. The reporting limit and detection limit 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 the 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 programme 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 at the monitoring stations
are shown in Appendix G.
5.37
During the reporting month, one (1) Action
Level exceedance and fifteen (15) Limit Level exceedances for dissolved oxygen,
eight (8) Limit level exceedances for turbidity, seven (7) Limit Level
exceedances for suspended solids and three (3) Action Level exceedance for arsenic of impact water
quality monitoring were recorded. The summary of exceedance records is shown in
Table 5.6 and Table 5.7.
Table 5.6 Summary
of Exceedance Records of Water Quality Monitoring in the Reporting Month
|
Date |
Monitoring Stations |
Parameter
(unit) |
Depth-averaged
Measured Value |
Exceedances |
Exceedances
due to the Contract |
|
|
AL |
LL |
|||||
|
2 June 2021 |
SYR-IS1 |
DO (mg/L) |
4.8 |
|
ü |
No |
|
SHST-IS2 |
DO (mg/L) |
6.8 |
ü |
|
No(ND/2019/04) |
|
|
Turb. (NTU) |
9.0 |
|
ü |
|||
|
MWR-IS3 |
DO (mg/L) |
6.6 |
|
ü |
No |
|
|
4 June 2021 |
SYR-IS1 |
DO (mg/L) |
5.6 |
|
ü |
No |
|
Arsenic (µg/L) |
14.5 |
ü |
|
|||
|
NTR-IS1 |
DO (mg/L) |
3.4 |
|
ü |
No |
|
|
SHST-IS2 |
DO (mg/L) |
6.4 |
|
ü |
Yes (ND/2019/04) |
|
|
Turb. (NTU) |
20.9 |
|
ü |
|||
|
SS (mg/L) |
33.5 |
|
ü |
|||
|
MWR-IS3 |
DO (mg/L) |
6.8 |
|
ü |
No |
|
|
Turb. (NTU) |
42.2 |
|
ü |
|||
|
SS (mg/L) |
68.5 |
|
ü |
|||
|
7 June 2021 |
SYR-IS1 |
Arsenic (µg/L) |
19.5 |
ü |
|
No |
|
NTR-IS1 |
DO (mg/L) |
5.4 |
|
ü |
No |
|
|
SHST-IS2 |
DO (mg/L) |
6.7 |
|
ü |
No |
|
|
Turb. (NTU) |
12.1 |
|
ü |
|||
|
SS (mg/L) |
10.0 |
|
ü |
|||
|
MWR-IS3 |
DO (mg/L) |
8.4 |
|
ü |
No |
|
|
9 June 2021 |
SYR-IS1 |
Arsenic (µg/L) |
18.5 |
ü |
|
No |
|
NTR-IS1 |
Turb. (NTU) |
38.4 |
|
ü |
No |
|
|
SS (mg/L) |
42.0 |
|
ü |
|||
|
SHST-IS2 |
DO (mg/L) |
6.5 |
|
ü |
No |
|
|
Turb. (NTU) |
12.8 |
|
ü |
|||
|
SS (mg/L) |
18.0 |
|
ü |
|||
|
MWR-IS3 |
DO (mg/L) |
6.7 |
|
ü |
No |
|
|
Turb. (NTU) |
26.1 |
|
ü |
|||
|
SS (mg/L) |
34.0 |
|
ü |
|||
|
11 June 2021 |
SYR-IS1 |
DO (mg/L) |
4.9 |
|
ü |
No |
|
NTR-IS1 |
DO (mg/L) |
5.1 |
|
ü |
No |
|
|
SHST-IS2 |
DO (mg/L) |
6.3 |
|
ü |
Yes (ND/2019/04) |
|
|
Turb. (NTU) |
12.1 |
|
ü |
|||
|
SS (mg/L) |
14.5 |
|
ü |
|||
|
MWR-IS3 |
DO (mg/L) |
7.7 |
|
ü |
No |
|
Abbreviation:
AL – Action Level, LL – Limit Level, DO – Dissolved Oxygen, Turb. – Turbidity,
SS – Suspended Solids
Table 5.7 Summary
of Exceedance Records of Water Quality Monitoring in the Reporting Month
|
Parameter |
No. of non-project related Exceedances |
Total No. of non-project related Exceedances |
No. of Exceedance
related to the Construction Works of the Contract |
Total No. of Exceedance related
to the Construction Works of the Contract |
||
|
Action Level |
Limit Level |
Action Level |
Limit Level |
|||
|
Dissolved Oxygen |
1 |
12 |
13 |
0 |
3 |
3 |
|
Turbidity |
0 |
5 |
5 |
0 |
3 |
3 |
|
Suspended Solids |
0 |
4 |
4 |
0 |
3 |
3 |
|
Arsenic |
3 |
0 |
3 |
0 |
0 |
0 |
5.38
Notifications of exceedance were issued to
relevant parties upon confirmation of the monitoring results. Investigation for
the exceedances recorded were conducted by ET accordingly. After investigation,
three (3) Limit Level exceedances for dissolved oxygen, three (3) Limit level
exceedances for turbidity and three (3) Limit Level exceedances for suspended
solids at monitoring station, SHST-IS2, were found due to Contract No.
ND/2019/04. Other exceedances were considered non-projected related. The
investigation results and summary of exceedances are summarised
in Table 5.8. The summary of
exceedance recorded in the reporting month is shown in Appendix O.
Table 5.8 Summary
of Investigation on Water Quality Monitoring Exceedance Records in the
Reporting Month
|
Date |
Monitoring Stations |
Parameters |
Investigation
Summary |
|
2, 4 and 11 June 2021 |
SYR-IS1 |
DO |
The exceedances are considered
not due to the Contract due to the following reasons: 1) No
pollution discharge from construction activity was observed; 2) DO value
at control station were measured lower than the water quality criteria at
SYR-IS1 (4 June 2021); 3) Water
temperature recorded were relatively higher that that during baseline
monitoring and led to low oxygen solubility in water. |
|
4, 7 and 9 June 2021 |
SYR-IS1 |
Arsenic |
No pollution discharge from
construction activity was observed. The exceedances are considered due to the
external factors rather than the contract works and non-project related. |
|
4, 7 and 11 June 2021 |
NTR-IS1 |
DO |
The exceedances are considered
not due to the Contract due to the following reasons: 1) No
pollution discharge from construction activity was observed; 2) DO value
at control station were measured lower than the water quality criteria at NTR-IS1
(4 and 11 June 2021); 3) Water
temperature recorded were relatively higher that that during baseline
monitoring and led to low oxygen solubility in water. |
|
9 June 2021 |
NTR-IS1 |
Turbidity and SS |
An influx of muddy water from a
tributary (out of Project boundary) to Ma Wat River and then to River Indus
was observed which affect the water quality of River Indus during the
monitoring day. No pollution discharge from construction activity under the
Project was observed. Rainfall was recorded before monitoring which led to
increased surface runoff and hence adverse water quality. The exceedances are
considered due to the external factors rather than the contract works and
non-project related. |
|
2 and 7 June 2021 |
SHST-IS2 |
DO, turbidity and SS |
No pollution discharge from
construction activity was observed. Rainfall was recorded before monitoring
which led to increased surface runoff and erosion from natural habitat along
the Siu Hang San Tsuen Stream, and also may cause the dispersion of riverbed
sediment to the monitoring station. (2 June 2021). DO value at control station were
measured lower than the water quality criteria at SHST-IS2. The exceeded
results were similar or within the ranges of baseline monitoring results. Water
temperature recorded were relatively higher that that during baseline
monitoring and led to low oxygen solubility in water. The exceedances are
considered due to the external factors rather than the contract works and
non-project related. |
|
4, 9 and 11 June 2021 |
SHST-IS2 |
DO, turbidity and SS |
Increased surface runoff from
rainfall recorded before and during the water quality monitoring may lead to
erosion from natural habitat along the stream, and also may cause the
dispersion of riverbed sediment to the monitoring station. During monitoring,
muddy surface runoff was observed between gaps of water barrier (under
Contract No. ND/2019/04) near Station SHST-IS2 which was considered as a
source of water pollution. In addition, DO value at control
station were measured lower than the water quality criteria at SHST-IS2.
Water temperature recorded were relatively higher that that during baseline
monitoring and led to low oxygen solubility in water. Remedial works were observed in progress
to clear the sediment trapped by desilting materials, provide concreting for
exposed site area near Siu Hang San Tsuen Stream and provide surface channels
for diverting storm water to wastewater treatment facilities. The following recommendations
on remedial measures were given as below and shall be maintained to avoid
further exceedances: 1) To
regularly clear the slurry and sediment trapped by desilting materials; 2) To
identify and minimise any source of surface runoff
within site area near Siu Hang San Tsuen Stream; 3) To
provide spare pumps for emergency use to pump muddy surface runoff to
wastewater treatment facilities after rainstorm; 4) To minimise area of exposed soil surface by covering with
impervious materials or clear loosen soil materials to reduce formation of
muddy surface runoff; 5) To
frequently check and ensure desilting materials for protection of Siu Hang
San Tsuen Stream are intact and in good condition; 6) To
provide channels, earth bunds or sand bag barriers to direct any muddy water
to silt removal facilities and away from Siu Hang San Tsuen Stream; 7) Regular
supervision and close monitoring on sediment control measures should be
conducted by designated foreman to ensure normal operation; and 8) Proposal
for mitigation measures on sediment control and contingency plan under
Contract No. ND/2019/04 should be submitted to avoid further exceedances. The
effectiveness of the remedial measures implemented should be closely reviewed The effectiveness of remedial
measures implemented by the Contractor would be continuously checked and
reviewed during water quality monitoring and weekly site inspection. |
|
2, 4, 7, 9 and 11 June 2021 |
MWR-IS3 |
DO,
Turbidity and SS |
Influx of muddy water from a
tributary (out of Project boundary) to Ma Wat River and then to the
monitoring stations was observed which affect the water quality of Ma Wat
River during the monitoring days. No pollution discharge from construction
activity under the Project was observed. DO value at control station were
measured lower than the water quality criteria at MWR-IS3 (2, 4, 9 and 11
June 2021). Water temperature recorded were relatively higher that that
during baseline monitoring and led to low oxygen solubility in water. The
exceedances are considered due to the external factors rather than the
contract works and non-project related. |
5.39
Proposal for mitigation measures on
sediment control and contingency plan under Contract No. ND/2019/04 were
submitted to ET, IEC and engineer for review. Remedial measures on sediment
control for Siu Hang San Tsuen Stream were proposed and implemented by the
Contractor under Contract No. ND/2019/04 and are partially listed as below:
Construction Runoff
l Excavated
materials generated from bored piling works shall be removed off-site and
disposed of immediately to prevent soil erosion;
l 2m-high
solid barrier are erected for protection of Siu Hang San Tsuen Stream.
Geotextile and sand bags are installed along the bottom of solid barrier to
prevent muddy runoff to the stream;
l Soil
materials trapped within geotextile shall be regularly cleared;
l Concrete
or tarpaulin sheet are provided to cover the exposed soil surface to reduce
muddy surface runoff;
l Surface
channels and earth bunds are provided for slope surface in site area near the
stream to direct storm water to silt removal facilities or wastewater treatment
facilities;
l Deposited
sand/silt shall be cleared regularly in silt removal facilities, channels and
manholes, especially after rainstorm;
General
Construction Activities and Measures
l The
exposure of soil on-site after excavation and backfilling shall be minimised where applicable to prevent washout of soil from
the site;
l Open
stockpiles of construction materials on-site shall be covered with tarpaulin
during rainstorms to prevent erosion;
l Wastewater
generated from site shall be collected and directed to the wastewater treatment
facilities for treatment prior to discharging to the public drain as specified
in the Effluent Discharge Licence;
l Wastewater
treatment facilities shall be inspected, maintained and cleaned as necessary by
a designated person to ensure proper and efficient operations of the
facilities, particularly after rainstorms; and
l Spare water pumps shall be prepared.
5.40
The effectiveness of remedial measures
implemented by the Contractor would be continuously checked and reviewed to
ensure proper implementation.
5.41
Should
any project related non-compliance of the criteria occur, action in accordance
with the Action Plan in Appendix N
shall be carried out.