3. WATER QUALITY Monitoring

Monitoring Requirement

3.1 The monitoring frequency will be once per month for six months at all designated monitoring stations during dry and wet season for Case 1 and 3. At the same time Case 2 and 4 will require a monitoring frequency of once per month for three months during dry season. The monitoring stations are listed in Table 3.1.

3.2 Water sampling will be conducted twice per monitoring day during mid-ebb and mid-flood tides at three water depths (1 meter below surface, mid-water depth and 1 meter above seabed). Parameters such as temperature, dissolved oxygen (DO) concentration, DO saturation, turbidity, salinity, pH and E. coli will be monitored.

3.3 Monitoring location/position, time, water depth, sampling depth, tidal stages, weather conditions and any special phenomena or work underway nearby were recorded.

Monitoring Locations

3.4 A total of 58 monitoring stations are designated for the water quality monitoring according to the EM&A manual, with the beach locations and the Fish Culture Zone being the sensitive receivers. The monitoring locations were chosen as close to the original coordinates as possible to ensure the collected samples are representative to the sensitive receivers.

3.5 The monitoring stations are illustrated in Figure 2-1, and the coordinates of the stations divided into the 4 Cases are shown in Table 3.1.

Table 3.1 Water Quality Monitoring Station

Station	Description	Easting	Northing
Case 1 - Emergency Discharge of Screened Sewage via all the Stage 1 and Stage 2 PTWs
B7	Anglers¡¦ Beach	823836.36	825044.52
B8	Gemini Beach	825215.29	824933.71
B9	Ho Mei Wan Beach	825388.98	825067.17
B10	Casam Beach	825731.46	825330.90
B11	Lido Beach	825917.78	825385.83
B12	Ting Kau Beach	826277.40	825519.01
B13	Approach Beach	827237.94	825301.02
B14	Ma Wan Beach	824431.47	823415.85
B24	Big Wave Bay Beach	843474.09	811730.33
B25	Rocky Bay Beach	844030.05	810286.64
B26	Shek O Beach	843891.17	809864.31
B30	St. Stephen¡¦s Beach	839990.14	808461.60
B31	Chung Hom Kok Beach	838616.79	808752.43
B32	South Bay Beach	838104.70	809598.73
B33	Middle Bay Beach	838056.97	809993.31
B34	Repulse Bay Beach	838008.93	810827.28
B35	Deep Water Bay Beach	836785.60	811635.55
F1	Tung Lung Chau Fish Culture Zone	847571.26	813102.00
F4	Lo Tik Wan Fish Culture Zone	831366.51	809221.48
F5	Ma Wan Fish Culture Zone	823875.25	823699.48
WSD4	Tsuen Wan flushing water intake	828908.71	825681.26
WSD5	Tsing Yi flushing water intake	829862.33	823104.16
WSD6	Cheung Sha Wan flushing water intake	833991.16	820235.42
WSD7	Kowloon South flushing water intake	833968.78	818053.54
WSD9	Tai Wan flushing water intake	837955.17	818412.01
WSD10	Cha Kwo Ling flushing water intake	841379.00	817859.28
WSD11	Yau Tong flushing water intake	842149.61	816974.14
WSD12	Tsueng Kwan O flushing water intake	845512.14	817421.15
WSD13	Siu Sai Wan flushing water intake	843904.21	814469.38
WSD15	Sai Wan Ho flushing water intake	841215.41	816451.38
WSD17	Quarry Bay flushing water intake	839685.64	817081.46
WSD18	Central Water Front flushing water intake	833935.18	816624.15
WSD19	Sheung Wan flushing water intake	833383.13	816836.34
WSD20	Kennedy Town flushing water intake	830826.34	816244.46
WSD21	Ap Lei Chau flushing water intake	834105.49	810567.95
WSD22	Wan Chai flushing water intake	836246.19	816134.92
VM12	Gradient Station	830542.34	821139.51
VM14	Gradient Station	829254.66	825159.72
VM15	Gradient Station	832707.02	818964.77
VM8	Gradient Station	830363.95	817092.23
VM7	Gradient Station	832495.44	817473.60
VM5	Gradient Station	836091.75	816541.13
VM2	Gradient Station	839713.80	817641.47
VM4	Gradient Station	838056.49	817637.50
VM1	Gradient Station	841809.43	816567.96
JM3	Gradient Station	844931.70	816956.95
EM1	Gradient Station	844379.62	815140.61
EM2	Gradient Station	845472.92	813712.75
EM3	Gradient Station	845771.79	810953.82
WM1	Gradient Station	830685.17	812441.28
WM2	Gradient Station	827881.70	816189.04
WM4	Gradient Station	825354.99	823325.61
SM3	Gradient Station	833462.67	809640.82
SM2	Gradient Station	836402.69	809492.93
MM13	Control Station	864290.82	808693.11
SM17	Control Station	814115.31	801690.83
Case 2 ¡V Temporary Bypass of Screened Sewage via the Stage 1 PTWs
B7	Anglers¡¦ Beach	823836.36	825044.52
B8	Gemini Beach	825215.29	824933.71
B9	Ho Mei Wan Beach	825388.98	825067.17
B10	Casam Beach	825731.46	825330.90
B11	Lido Beach	825917.78	825385.83
B12	Ting Kau Beach	826277.40	825519.01
B13	Approach Beach	827237.94	825301.02
B14	Ma Wan Beach	824431.47	823415.85
B24	Big Wave Bay Beach	843474.09	811730.33
B25	Rocky Bay Beach	844030.05	810286.64
B26	Shek O Beach	843891.17	809864.31
F1	Tung Lung Chau Fish Culture Zone	847571.26	813102.00
F5	Ma Wan Fish Culture Zone	823875.25	823699.48
WSD5	Tsing Yi flushing water intake	829862.33	823104.16
WSD6	Cheung Sha Wan flushing water intake	833991.16	820235.42
WSD7	Kowloon South flushing water intake	833968.78	818053.54
WSD9	Tai Wan flushing water intake	837955.17	818412.01
WSD10	Cha Kwo Ling flushing water intake	841379.00	817859.28
WSD11	Yau Tong flushing water intake	842149.61	816974.14
WSD12	Tsueng Kwan O flushing water intake	845512.14	817421.15
WSD13	Siu Sai Wan flushing water intake	843904.21	814469.38
WSD15	Sai Wan Ho flushing water intake	841215.41	816451.38
WSD17	Quarry Bay flushing water intake	839685.64	817081.46
WSD18	Central Water Front flushing water intake	833935.18	816624.15
WSD19	Sheung Wan flushing water intake	833383.13	816836.34
WSD20	Kennedy Town flushing water intake	830826.34	816244.46
WSD22	Wan Chai flushing water intake	836246.19	816134.92
VM12	Gradient Station	830542.34	821139.51
VM14	Gradient Station	829254.66	825159.72
VM15	Gradient Station	832707.02	818964.77
VM8	Gradient Station	830363.95	817092.23
VM7	Gradient Station	832495.44	817473.60
VM5	Gradient Station	836091.75	816541.13
VM2	Gradient Station	839713.80	817641.47
VM4	Gradient Station	838056.49	817637.50
VM1	Gradient Station	841809.43	816567.96
JM3	Gradient Station	844931.70	816956.95
EM1	Gradient Station	844379.62	815140.61
EM2	Gradient Station	845472.92	813712.75
EM3	Gradient Station	845771.79	810953.82
MM13	Control Station	864290.82	808693.11
SM17	Control Station	814115.31	801690.83
Case 3 - Emergency Discharge of Undisinfected CEPT Effluent via the SCISTW Outfall
B7	Anglers¡¦ Beach	809640.82	833462.67
B8	Gemini Beach	809492.93	836402.69
B9	Ho Mei Wan Beach	806868.38	851275.55
B10	Casam Beach	801678.43	826182.25
B11	Lido Beach	825917.78	825385.83
B12	Ting Kau Beach	826277.40	825519.01
B13	Approach Beach	827237.94	825301.02
B14	Ma Wan Beach	824431.47	823415.85
F5	Ma Wan Fish Culture Zone	823875.25	823699.48
WSD18	Central Water Front	833935.18	816624.15
WSD19	Sheung Wan	833383.13	816836.34
WSD20	Kennedy Town	830826.34	816244.46
WM4	Gradient Station	825354.99	823325.61
VM8	Gradient Station	830363.95	817092.23
VM7	Gradient Station	832495.44	817473.60
SM6	Control Station	826179.81	805902.89
SM12	Control Station	819524.17	808420.40
Case 4 - Bypass of Screened Sewage from NWKPTW at the Seawall of Stonecutters¡@Island
B7	Anglers¡¦ Beach	809640.82	833462.67
B8	Gemini Beach	809492.93	836402.69
B9	Ho Mei Wan Beach	806868.38	851275.55
B10	Casam Beach	801678.43	826182.25
B11	Lido Beach	825917.78	825385.83
B12	Ting Kau Beach	826277.40	825519.01
B13	Approach Beach	827237.94	825301.02
B14	Ma Wan Beach	824431.47	823415.85
F5	Ma Wan Fish Culture Zone	823875.25	823699.48
VM14	Gradient Station	829254.66	825159.72
WM4	Gradient Station	825354.99	823325.61
SM6	Control Station	826179.81	805902.89
SM12	Control Station	819524.17	808420.40

Monitoring Schedule

3.6 The water quality monitoring was conducted from September 2017 to February 2018. The monitoring schedule is shown in Appendix A.

Monitoring Equipment

3.7 For in-situ monitoring, a multi-parameter meter (YSI EXO1) will be used to measure DO, DO saturation, turbidity, salinity, pH and temperature. The equipment used in the water quality monitoring is summarized in Table 3.2 and the copies of calibration certificates are shown in Appendix B.

Table 3.2 Marine Water Quality Monitoring Equipment

Equipment	Model and Make
Water Sampler	Kahlsico Water Sampler 13SWB203
Multi-parameter Water Quality Probe	YSI EXO1 Multiparameter Sondes

3.8 The specification of the standard electrodes of the YSI EXO1 for in-situ monitoring is summarized in Table 3.3

Table 3.3 In-situ parameters¡¦ measuring range

Dissolved Oxygen	Range	0 - 50 mg/L
	Accuracy	¡Ó0.1 mg/L
pH	Range	0 ¡V 14 pH
	Accuracy	¡Ó 0.1 pH
Temperature	Range	-5˚C ¡V 50˚C
	Accuracy	¡Ó 0.01˚C
Turbidity	Range	0 to 4000 FNU
	Repeatability	¡Ó 2% of reading
Salinity	Range	0 ¡V 70.00 ppt
	Accuracy	¡Ó 1% of reading

Notes:

- Accuracy: the qualitative concept of an agreeable closeness between the results of the measurement and the true value of the measured samples.

3.9 A portable, battery-operated and hand held echo sounder (e.g. Garmin Fishfinder 140) will be used for the determination of water depth at each designated monitoring station.

3.10 Hand-held GPS (Magellan eXplorist GC) will be used to ensure the monitoring vessel is at the correct location before taking measurements.

Monitoring Parameters and Frequency

3.11 Table 3.4 summarizes the monitoring parameters, monitoring period and frequencies of the water quality monitoring.

Table 3.4 Water Quality Monitoring Parameters and Frequency

Parameters, unit	Depth	Frequency
In-situ Parameters: ¡P Temperature ¡P pH ¡P Water depth ¡P DO, mg/L ¡P DO Saturation, % ¡P Salinity, ppt ¡P Turbidity, NTU	¡P 3 water depths: 1m below water surface, mid-depth and 1m above sea bed. ¡P If the water depth is less than 3m, mid-depth sampling only. ¡P If the water depth is between 3-6m, omit mid-depth sampling.	¡P Baseline monitoring: once per month for 6 months
Laboratory Testing Parameters: ¡P E. coli, cfu/100ml

Monitoring Methodology

3.12 Multi-parameter meter (e.g. YSI EXO1) was used to measure the in-situ parameter. At each measurement, two consecutive measurements of pH level, DO concentration, DO saturation, salinity, turbidity and temperature will be taken. Where the difference in the value between the first and second readings of each set is more than 25% of the value of the first reading, the reading will be discarded and further readings will be taken. A single measured sample at each water depth will be collected for E. coli analysis.

3.13 Each water sample of about 250 ml were collected and stored in glass bottles. The sample bottles were packed into ice-box and delivered to a HOKLAS-accredited Laboratory, WELLAB Ltd., for the analysis of E. coli within 24 hours.

QA/QC for Laboratory Analysis

3.14 The testing laboratory implemented QA/QC measures for the analysis of water samples in order to obtain reliable data that is technically defendable, which including the followings:

Medium Quality Control

1.

2.

3.

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

3.10

3.11

3.12

3.13

3.14 Medium quality control samples were prepared to check the signs of contamination and deterioration of the culture medium for E. coli growth. Test for those organisms showed different colours of colonies, such as E. aerogenes, P. aeruginosa, K. pneumoniae and E. faecalis, were also included in the medium quality control samples.

Method Quality Control

3.15 A laboratory blank sample was analysed under the same sample preparation and analytical procedure as the field samples. Method blank sample is to assess if there is contamination during laboratory testing.

3.16 Positive control and negative control samples were prepared to ensure colonies would show their respective colours on the culture medium.

QC laboratory sample duplicate

3.17 At least one set of QC sample was analysed for each batch of samples ≤ 20 samples. The sample duplicate test results were used to assess the precision of the analytical process.

3.18 The analysis will commence within 24 hours after collection of the water samples. The list of parameter to be analysed as well as the suggested corresponding analytical method and reporting limit are listed in Table 3.5.

Table 3.5 Suggested Analytical Method for Laboratory Analysis for Marine Water Samples

Maintenance and Calibration

3.19 Before each round of monitoring, a zero check in distilled water will be performed with the probes in the YSI EXO1. The probes will be calibrated with a known standard solution.

3.20 Laboratory testing for E. coli which is analysed in the HOKLAS-accredited laboratory, WELLAB Ltd, are attached in Appendix E.