4. WATER QUALITY

Monitoring Requirement

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. 1 m below surface, mid-depth and 1 m from seabed). Duplicate readings were taken for each depth.

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.

Monitoring Equipment

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) 2.2 L

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 %

Monitoring Locations

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 4.1a and 4.1b show the location of the monitoring stations.

Table 4.4 Marine Water Quality Monitoring Stations

Station I.D.	Description	HK 1980 Grid		Status	Monitoring Parameter
		Northing	Easting
MW1	Gemini Beach	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	Casam Beach	825293.1	825737.9	Impact
MW4	Lido Beach	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	Ma Wan Fish Culture Zone	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 6m, all in-situ measurements and samplings were conducted at 3 water depths, namely 1m below water surface, mid-depth, and 1m from seabed.

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 4^oC, 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 O.

Maintenance / Calibration

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.

Results and Observations

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 N 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	2	0	0	0	0	0	2
	Limit	0	2	0	0	4	0	4	2
MW2	Action	0	0	0	0	0	0	0	0
	Limit	0	4	0	0	4	0	4	4
MW3	Action	0	2	0	0	1	0	1	2
	Limit	0	4	0	0	2	0	2	4
MW4	Action	0	1	1	0	3	0	4	1
	Limit	0	4	0	0	0	0	0	4
MW5	Action	1	2	2	0	1	1	4	3
	Limit	0	3	0	0	1	1	1	4
MW6	Action	0	1	0	1	0	0	0	2
	Limit	0	3	0	0	3	1	3	4
WFCZF1	Action	1	0	2	0	0	0	3	0
	Limit	3	4	0	0	3	0	6	4
Total	Action	2	8	5	1	5	1	12	10
	Limit	3	24	0	0	17	2	20	26

4.18 There were 22 action and 46 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	Aug 06	Sep 06	% Difference
No. of Monitoring days	-	13	13	-
DO (S&M)	Action	0	4	-
	Limit	0	12	-
	Total	0	16	-
	Total/Monitoring Day	0.00	1.23	0.00
DO (B)	Action	6	6	-
	Limit	3	15	-
	Total	9	21	-
	Total/Monitoring Day	0.69	1.62	134.78
Turbidity	Action	3	6	-
	Limit	1	0	-
	Total	4	6	-
	Total/Monitoring Day	0.31	0.46	48.39
SS	Action	10	6	-
	Limit	6	19	-
	Total	16	25	-
	Total/Monitoring Day	1.23	1.92	56.10
Total number of DO, Turbidity and SS exceedance	Action	19	22	-
	Limit	10	46	-
	Total	29	68	-
	Total/Monitoring Day	2.23	5.23	134.53

Note: Total/Monitoring Day = Total no. of exceedances per monitoring day

4.1 The number of DO, turbidity, SS and overall exceedance per monitoring day increased in reporting month when compared with those in August 2006. This may possibly due to adverse and windy weather during the monitoring period.