4.1
During the course of the marine works, impact marine water quality
monitoring was required 3 days per week, at mid-flood and mid-ebb tides, with
sampling/measurement at the designated monitoring stations in accordance with
the Marine Water Quality Monitoring and Audit Manual (Rev.2). The interval
between two sets of monitoring was more than 36 hours.
4.2
Measurements were taken at each station within one hour either side of
mid‑ebb and mid-flood at three depths (i.e.
4.3
A few minor comments were received from EPD on the Marine Water Quality
Baseline Monitoring Report (Rev.2) on 27 August 2003. As advised by EPD, the
upstream control stations of MW5 & MW6 during mid-flood tide had been
revised to MR5 & MR6 respectively, while there would not be any upstream
control station for WFCZF1 during mid-flood tide. The revised pages were
submitted to all the relevant parties on 1 September 2003 after IC(E)’s
verification. No further comment was received in the reporting month. Details
of the monitoring requirement are provided in Appendix B.
4.4
Table 4.1 summarises the equipment used in the marine water quality
impact monitoring programme. A copy of the calibration certificates for the
monitoring equipment is attached in Appendix D.
Table 4.1 Water Quality Monitoring Equipment
|
Equipment |
Model
and Make |
|
DO
& Temperature Meter, Salinity Meter & Turbidimeter |
YSI
Model 6820 CE-C-M-Y |
|
Positioning
Equipment |
Trimble
NT200D DGPS |
|
Water
Depth Detector |
Horizontal
Strike 200 |
|
Water Sampler |
Kahlsio
Water Sampler (Vertical) |
Monitoring Parameters, Frequency and Schedule
4.5
Table 4.2 summarises the monitoring parameters and frequency of water
quality monitoring. The monitoring schedule is attached in Appendix C.
Table 4.2 Water Quality Monitoring Parameters and
Frequency
|
Monitoring Stations |
Parameter, unit |
Frequency |
No. of Depths |
No. of Samples |
|
Control Stations: MC1, MC2 Reference Stations: MR5 & MR6 Sensitive
Receiver Stations: MW1 – MW6 & WFCZF1 |
· Depth, m · Temperature, ºC · Salinity, ppt · DO, mg/L · DO Saturation, % · Turbidity, NTU · SS, mg/L |
Three times per week |
3 (Surface, Mid-Depth and Bottom) |
Duplicate sample (Mid-ebb & Mid-flood) |
4.6
The limits of detection for the in-situ and laboratory measurements
obtained are summarised in Table 4.3.
Table
4.3 Limits of Detection for the
In-situ and Laboratory Measurements
|
Determinant |
Limit of Detection |
Precision |
|
Dissolved Oxygen |
0. 1 mg/L |
1 % |
|
Salinity |
0.01 ppm |
1 % |
|
pH |
0.01 units |
1 % |
|
Temperature |
0. 1 degree Celsius |
1 % |
|
Turbidity (NTU) |
0. 1 NTU |
1 % |
|
Suspended Solids |
1 mg/L |
2 % |
4.7
In accordance with the Marine
Water Quality Monitoring and Audit Manual (Rev.2), the marine water quality monitoring
stations are shown in Table 4.4. Figures
Table 4.4 Marine Water Quality Monitoring
Stations
|
Station I.D. |
Description |
HK 1980 Grid |
Status |
Monitoring Parameter |
|
|
Northing |
Easting |
||||
|
MW1 |
|
824933.2 |
825214.5 |
Impact |
· Suspended solids · Turbidity · Dissolved Oxygen · Depth · Temperature · Salinity · DO Saturation |
|
MW2 |
Hoi Mei Beach |
825056.7 |
825423.2 |
Impact |
|
|
MW3 |
|
825293.1 |
825737.9 |
Impact |
|
|
MW4 |
|
825281.6 |
825874.8 |
Impact |
|
|
MW5 |
Sham Tseng East Reclamation |
824935.0 |
824834.0 |
Impact |
|
|
MR5 |
824910.0 |
824815.0 |
Reference |
||
|
MW6 |
824906.0 |
824887.0 |
Impact |
||
|
MR6 |
824881.0 |
824873.0 |
Reference |
||
|
WFCZF1 |
|
823870.0 |
823500.0 |
Impact |
|
|
MC1 |
Ebb-tide Control Station |
824888.0 |
824403.4 |
Reference |
|
|
MC2 |
Flood-tide Control Station |
824834.5 |
825100.0 |
Reference |
|
Monitoring Methodology and Calibration
Details
4.8
The following procedures were adopted for DO, temperature, salinity,
turbidity and suspended solids measurements:
Instrumentation
4.9
The in-situ water quality parameters, viz. dissolved oxygen, temperature, salinity and turbidity were measured by a
multi-parameter meter (Model YSI 6820 CE-C-M-Y).
Operating/Analytical Procedures
4.10
Given that all water monitoring stations had water depths over
4.11
At each sampling depth, duplicate readings of
dissolved oxygen content and turbidity 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 between the first and second readings of each set was more than 25% of
the value of the first reading, a third measurement would be conducted to
ensure data precision.
4.12
Water samples were collected by water samplers and stored in
polyethylene bottles. Sampling bottles were pre-rinsed with the same water
samples. The sample bottles were then
packed into a cool-box kept at 4oC, and delivered to a HOKLAS
accredited Laboratory (ALS) for the analysis of suspended solids. For QA/QC, one duplicate sample
from every batch of 20 samples was analysed as required by the HOKLAS. The QC results are summarized in Appendix L.
4.13
Before each round of monitoring, the dissolved
oxygen probe of YSI 6820 was calibrated by the wet bulb method.
4.14
Before each round of monitoring, a zero check in distilled water was
performed on the turbidity probe of YSI 6820. The probe was then calibrated
with a solution of known NTU.
4.15
In the reporting month, thirteen monitoring sessions were carried out.
The monitoring events were conducted in accordance with the schedule.
4.16
Appendix K presents the water quality monitoring data and graphical
presentations of monitoring results respectively.
4.17
Total number of exceedances in the reporting month at each sensitive
receiver are summarised in Table 4.5.
Table 4.5 Summary
of Total Number of Exceedances in the Reporting Month
|
Location |
Exceedance Level |
DO |
Turbidity |
SS |
Total |
||||
|
Mid-ebb |
Mid-flood |
Mid-ebb |
Mid-flood |
Mid-ebb |
Mid-flood |
Mid-ebb |
Mid-flood |
||
|
MW1 |
Action |
0 |
1 |
0 |
0 |
1 |
0 |
1 |
1 |
|
Limit |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
|
|
MW2 |
Action |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |
|
Limit |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
|
|
MW3 |
Action |
0 |
1 |
0 |
0 |
2 |
0 |
2 |
1 |
|
Limit |
0 |
0 |
0 |
0 |
3 |
2 |
3 |
2 |
|
|
MW4 |
Action |
0 |
0 |
0 |
0 |
2 |
0 |
2 |
0 |
|
Limit |
0 |
0 |
0 |
0 |
3 |
2 |
3 |
2 |
|
|
MW5 |
Action |
0 |
7 |
0 |
0 |
0 |
2 |
0 |
9 |
|
Limit |
0 |
1 |
0 |
0 |
3 |
3 |
3 |
4 |
|
|
MW6 |
Action |
0 |
7 |
0 |
0 |
2 |
0 |
2 |
7 |
|
Limit |
0 |
0 |
0 |
0 |
2 |
0 |
2 |
0 |
|
|
WFCZF1 |
Action |
3 |
0 |
0 |
0 |
1 |
0 |
4 |
0 |
|
Limit |
0 |
4 |
0 |
0 |
1 |
0 |
1 |
4 |
|
|
Total |
Action |
3 |
16 |
0 |
0 |
9 |
3 |
12 |
19 |
|
Limit |
0 |
5 |
0 |
0 |
14 |
7 |
14 |
12 |
|
4.18
There were 31 action and 26 limit level exceedances reported in the
month. As there was no marine work conducted at the Reclamation Site, all
exceedances were considered not related to the Project.
Assessment of
Environmental Monitoring Results
4.19
Summary of total number of exceedances and exceedance per monitoring day
is presented in Table 4.6. Comparison of these parameters, percentage
difference of total number of exceedances and percentage difference of number
of exceedances at each sensitive receiver station of this reporting month with
last reporting month is also shown in this table.
Table 4.6 Total Number of Water Quality
Exceedances in the Reporting Month and Previous Month
|
Parameter |
Exceedance Level |
Oct 06 |
Nov 06 |
% Difference |
|
No. of Monitoring days |
- |
12 |
13 |
- |
|
DO (S&M) |
Action |
4 |
17 |
- |
|
Limit |
1 |
5 |
- |
|
|
Total |
5 |
22 |
- |
|
|
Total/Monitoring Day |
0.42 |
1.69 |
302.38 |
|
|
DO (B) |
Action |
0 |
2 |
- |
|
Limit |
0 |
0 |
- |
|
|
Total |
0 |
2 |
- |
|
|
Total/Monitoring Day |
0 |
0.15 |
150.00 |
|
|
Turbidity |
Action |
5 |
0 |
- |
|
Limit |
2 |
0 |
- |
|
|
Total |
7 |
0 |
- |
|
|
Total/Monitoring Day |
0.58 |
0.00 |
-580.00 |
|
|
SS |
Action |
14 |
12 |
- |
|
Limit |
5 |
21 |
- |
|
|
Total |
19 |
33 |
- |
|
|
Total/Monitoring Day |
1.58 |
2.54 |
60.56 |
|
|
Total number of DO,
Turbidity and SS exceedance |
Action |
23 |
31 |
- |
|
Limit |
8 |
26 |
- |
|
|
Total |
31 |
57 |
- |
|
|
Total/Monitoring Day |
2.58 |
4.38 |
69.77 |
Note: Total/Monitoring
Day = Total no. of exceedances per monitoring day
4.20
The number of DO, SS and overall exceedance per monitoring day increased
in reporting month when compared with those in October 2006.