4. WATER QUALITY

4.1 Introduction

4.1.1.1 Water quality impacts arising from the carrying out of construction and operational activities would be minimised by implementation of suitable mitigation measures and through good management practices. Contractual documents for the San Wai STW and Ha Tsuen Pumping Station should incorporate the mitigation measures for water pollution control as recommended in the EIA report.

4.1.1.2 Site audit should be implemented to ensure that the mitigation measures recommended in the EIA report are fully implemented during the construction and operational phases of the San Wai STW and Ha Tsuen Pumping Station.

4.2 Monitoring Equipment

Dissolved Oxygen and Temperature Measuring Equipment

4.2.1.1 The instrument should be a portable, weatherproof dissolved oxygen measuring instrument complete with cable, sensor, comprehensive operation manuals, and use a DC power source. It should be capable of measuring:
· a dissolved oxygen level in the range of 0?20 mg/L and 0?200% saturation; and
· a temperature of 0?45 degree Celsius.

4.2.1.2 It should have a membrane electrode with automatic temperature compensation complete with a cable. Sufficient stocks of spare electrodes and cables should be available for replacement where necessary. (e.g. YSI model 59 meter, YSI 5739 probe, YSI 5795A submersible stirrer with reel and cable or an approved similar instrument).

4.2.1.3 Should salinity compensation not be built-in in the DO equipment, in-situ salinity should be measured to calibrate the DO equipment prior to each DO measurement.

Turbidity Measurement Instrument

4.2.1.4 The instrument should be a portable, weatherproof turbidity-measuring instrument complete with comprehensive operation manual. The equipment should use a DC power source. It should have a photoelectric sensor capable of measuring turbidity between 0?1000 NTU (e.g. Hach model 2100P or an approved similar instrument).

Salinity

4.2.1.5 A portable salinometer capable of measuring salinity in the range of 0-40 ppt should be provided for measuring salinity of the water at each monitoring location.

Positioning Device

4.2.1.6 The locations of water monitoring points should be located using a hand-held or boat-fixed digital Global Positioning System (GPS) or other equivalent instrument of similar accuracy. This is to ensure that the water sampling locations are correct during the water quality monitoring work.

Water Depth Detector

4.2.1.7 A portable, battery-operated echo sounder should be used for the determination of water depth at each designated monitoring station. This unit can either be handheld or affixed to the bottom of the work boat, if the same vessel is to be used throughout the monitoring programme.

Water Sampling Equipment

4.2.1.8 A transparent PVC or glass cylinder, which has a volume of not less than 2 litres and can be sealed at both ends with cups, should be used for collection of water samples at various depths. The water sampler should be equipped with a positive latching system. During water sampling, a messenger is released to trigger the closure of the water sampler at suitable water depth.

4.2.1.9 All in-situ monitoring instruments should be checked, calibrated and certified by a laboratory accredited under HOKLAS or any other international accreditation scheme before use, and subsequently re-calibrated at 3 monthly intervals throughout all stages of the water quality monitoring. Responses of sensors and electrodes should be checked with certified standard solutions before each use. Wet bulb calibration for a DO meter should be carried out before measurement at each monitoring location.

4.2.1.10 For the on site calibration of field equipment, the BS 127:1993, Guide to Field and On-Site Test Methods for the Analysis of Water should be observed.

4.2.1.11 Sufficient stocks of spare parts should be maintained for replacements when necessary. Backup monitoring equipment shall also be made available so that monitoring can proceed uninterrupted even when some equipment is under maintenance, calibration, etc.

4.3 Construction Phase Effluent Discharge Monitoring

Water Quality Parameters

4.3.1.1 Effluent discharged from the construction sites would enter the local streams and eventually discharged to Deep Bay. The Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM) issued under section 21 of the WPCO defines the quality of effluents discharged into these waters. The discharge licence issued by EPD would be based on the TM to specify the maximum discharge limits of relevant parameters. For different discharge flow rates, the effluent standards vary slightly. Estimation of discharge flow rate is required when applying for the discharge licence from EPD. With regard to the construction site discharges, the major parameters to be monitored would include suspended solids (SS), pH, chemical oxygen demand (COD) and others as specified in the discharge licence. All the parameters shall be analyzed in a HOKLAS or other international accredited laboratory.

4.3.1.2 The Environmental Team (ET) shall be responsible for monitoring the quality of effluent discharged from the construction sites to ensure the effluent quality is in compliance with the discharge licence conditions. Monitoring of the discharge flow rate is required. In case where the actual discharge flow rate is significantly different from the allowable flow rate specified in the discharge licence, the discharge licence holder shall inform EPD and apply for a variation of the licence conditions.

4.3.1.3 A sample monitoring record sheet is shown in Table 4.1 for reference.

Name & Designation Signature Date

Recorded By:________________________ ________________ ________________

Checked By:________________________ ________________ ________________

Note:
The laboratory results for the monitored parameters are to be filled up once they are available from the laboratory.

Laboratory Analysis

4.3.1.4 Water samples of effluent shall be collected at the final discharge point as indicated in the discharge licence. In-situ measurement of the pH values of the discharged effluent shall be undertaken by using a calibrated pH meter. Analysis of SS and COD shall be carried out in a HOKLAS or other international accredited laboratory. It is necessary to collect a sufficient volume of grab samples for carrying out the laboratory analysis. The SS and COD determination should follow APHA 17ed 2540D and APHA 17ed 5220 C&D respectively or equivalent methods subject to approval of DEP. The laboratory analysis work should start within 24 hours after collection of the samples. Complete records of the laboratory results shall be properly maintained.

Monitoring Locations

4.3.1.5 Impact monitoring of effluent quality shall be carried out at representative discharge points where effluent from the construction sites is discharged into the local water courses after being treated in a wastewater treatment system.

4.3.1.6 Runoffs and wastewater generated from the construction activities in different sections of the construction sites should be collected and transported to these discharge locations. After the removal of suspended solids and other pollutants, the treated effluent would be discharged at the designated discharge points.

Impact Monitoring and Remedial Actions

4.3.1.7 During the construction period, routine monitoring shall be undertaken to ensure that the effluent quality is in compliance with the requirements specified in the discharge licence. The monitoring shall be carried out at least once every two weeks. When exceedance of the discharge standards is detected, the monitoring frequency shall be increased to examine the effluent quality on a daily basis until the exceedance is rectified. In case of sampling frequency being specified in the discharge licence, the ET should carry out the monitoring in accordance with the requirements. Monitoring records and laboratory results need to be properly maintained and submitted to the officers of EPD for inspection upon request.

4.3.1.8 When non-compliance of the effluent quality is detected, the ET shall inform the Contractor and identify the sources of pollutants and causes of non-compliance. The causes may be a result of sudden increases in pollution loads and flows from the construction or operation activities. It may also be related to lack of protective works provided in the project site. Remedial actions are required to ensure that the recommended mitigation measures are fully implemented and the non-compliance is suitably rectified. Details of the Action Plan are summarized in Table 4.2.

Table 4.2  Action Plan for Monitoring of Effluent Discharge 

4.4 Construction Phase Monitoring at Local Stream Course

Water Quality Parameters

4.4.1.1 The ET shall be responsible for monitoring the levels of turbidity, dissolved oxygen and suspended solids to ensure that any deterioration of water quality in the selected local stream course is readily detected and timely action is taken to rectify the situation.

Laboratory Analysis

4.4.1.2 Water samples shall be collected at mid-depth at selected sampling location. The parameters of turbidity and dissolved oxygen shall be measured in-situ and the suspended solids shall be analyzed in a HOKLAS or other international accredited laboratory.

4.4.1.3 The laboratory analysis for suspended solids should start within 24 hours after collection of the water samples. The SS determination should follow APHA 17ed 2540D or equivalent methods subject to approval of DEP. Complete records of the laboratory results should be properly maintained.

Monitoring Locations

4.4.1.4 The proposed monitoring location is located at Tin Shui Wai Nullah and is shown in Figure 4.2. The purpose of the river impact monitoring programme is to ensure that the WQ in the river would not deteriorate after receiving the treated effluents from the construction sites. Therefore, the "control" could be the WQ measurements before the commissioning of the construction work at the same monitoring location. As the construction work would extend to the upstream of the nullah, only one impact monitoring station that is potentially affected by the works is selected. No upstream control monitoring points are proposed.

Baseline/Impact Monitoring and Remedial Actions

4.4.1.5 Baseline conditions of the selected local stream course shall be established and agreed with DEP prior to the commencement of construction works. The water quality parameters including turbidity, dissolved oxygen and suspended solids shall be measured in the baseline monitoring. The measurements shall be taken at the proposed monitoring station at Tin Shui Wai Nullah as shown in Figure 4.2, 3 days per week for at least four weeks prior to the commencement of construction works. During the baseline monitoring, there shall be no construction activities in the vicinity of the monitoring stations.

4.4.1.6 In case that insufficient baseline monitoring data or questionable results are obtained, the ET Leader shall seek approval from the IEC and DEP on an appropriate set of data to be used as baseline reference.

4.4.1.7 Baseline monitoring schedule shall be faxed to EPD 1 week prior to the commencement of baseline monitoring. The interval between 2 sets of monitoring shall not be less than 36 hours.

4.4.1.8 During the construction period, impact monitoring shall be carried out on three occasions per week. The interval between two sets of monitoring shall not be less than 36 hours except where there are exceedances of Action and/or Limit levels, in which case the monitoring frequency shall be increased.

4.4.1.9 Upon completion of the construction activities, a post project monitoring exercise on selected local stream water quality shall be undertaken for four weeks in the same manner as the impact monitoring.

4.4.1.10 The water quality monitoring schedule shall be faxed to EPD on or before the first day of the monitoring month, EPD shall be notified immediately of any changes in schedule by fax. The Action and Limit levels for local stream course water quality monitoring are shown in Table 4.3. Should the monitoring results at any designated monitoring stations indicate that the Action and Limit levels are exceeded, the actions specified in Table 4.4 shall be carried out.

Table 4.4  Event and Action Plan for Local Stream Water Quality  

4.5 Operational Phase Marine Water Quality Monitoring

Water Quality Parameters

4.5.1.1 The operational phase marine water monitoring aims to quantify the variability of pollutants in the marine waters. Measured pollutant concentrations will be compared with relevant Water Quality Objectives and the baseline data to identify any significant impacts on water quality directly attributable to the Project. The ET shall be responsible for marine water quality monitoring.

4.5.1.2 Monitoring of turbidity, pH, dissolved oxygen (DO), suspended solids (SS), total inorganic nitrogen (TIN), unionised ammonia (NH3-N), 5-day biochemical oxygen demand (BOD5), E. coli, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and heavy metals shall be included. The first three parameters can be measured in-situ whilst the others are determined in laboratory.

4.5.1.3 In association with the water quality parameters, some relevant data should also be measured/recorded, such as monitoring location/position, sampling time, water depth, water temperature, salinity, dissolved oxygen saturation, weather conditions, sea conditions, tidal stage, and any special phenomena and work being carried out at the construction site. A sample marine water quality monitoring data record sheet is shown in Appendix B for reference. The following gives a list of the parameters to be measured and analysed:

In-situ Measurement

· pH
· Dissolved oxygen (mg/L and % saturation)
· Temperature (oC)
· Turbidity (NTU)
· Salinity (ppt)
· Water depth (m)

Laboratory Analysis

· Suspended solids (mg/L)
· Total inorganic nitrogen (mg/L)
· Unionised ammonia (mg/L)
· 5-day biochemical oxygen demand (mg/L)
· E. coli (cfu/100mL)
· Cadmium, Copper, Nickel, Lead, Chromium, Mercury and Zinc (µg/L)
· PCBs (µg/L)
· PAHs (µg/L)

Laboratory Analysis

4.5.1.4 Water samples should be analysed in a HOKLAS or other international accredited laboratory. The analyses for SS, TIN, NH3-N, BOD and E. coli should follow the American Public Health Association (APHA) Standard Methods for the Examination of Water and Wastewater, 19th edition, unless otherwise specified (see Table 4.5). The analyses for heavy metals, PCBs and PAHs should also follow the APHA standard methods or other equivalent international methods to be agreed with EPD prior to the monitoring work.

4.5.1.5 Water samples of about 2 litres should be collected at the monitoring stations for carrying out the laboratory analysis. The analysis should commence within 24 hours after collection of the water samples.

Table 4.5  Analytical Methods to be applied to Marine Water Quality Samples

Monitoring Locations

4.5.1.6 The marine water monitoring locations are shown in Figure 4.1. It is recommended to set up 8 monitoring stations (W1 to W8). Table 4.6 presents the co-ordinates of the stations.

Table 4.6  Co-ordinates of the Marine Water Quality Monitoring Stations

4.5.1.7 The status and locations of water quality sensitive receivers may change after issuing this Manual. If such cases exist, the ET should propose updated monitoring locations and seek approval from DEP.

4.5.1.8 Measurements should be taken at 3 water depths, namely, 1m below water surface, mid-depth and 1m above seabed, except where the water depth less than 6m, the mid-depth station may be omitted. Should the water depth be less than 3m, only the mid-depth station should be monitored.

Baseline Marine Water Monitoring

4.5.1.9 Baseline conditions for water quality should be established and agreed with DEP prior to the commencement of works. The purposes of the baseline monitoring are to establish ambient conditions prior to the commencement of the Project and to demonstrate the suitability of the proposed monitoring stations. The baseline conditions should normally be established by measuring the water quality parameters specified in Section 4.5.1.3. The proposed marine water quality stations are discussed in Section 4.5.1.6 and are shown in Figure 4.1.

4.5.1.10 The measurements should be taken at all monitoring stations on 4 occasions at intervals of approximately 3 months during the baseline phase prior to the operation of the upgraded and expanded San Wai STW and expanded Ha Tsuen PS. On each occasion, marine water samples shall be collected every 2 hours for a 12-hour duration.

4.5.1.11 In exceptional case when insufficient baseline monitoring data or questionable results are obtained, the ET should seek approval from DEP on an appropriate set of data to be used as baseline reference.

Operational Phase Marine Water Monitoring

4.5.1.12 After the commissioning of the expanded and upgraded San Wai STW, initial monitoring should be undertaken to gauge how the water quality changes against the baseline measurements and the prediction made in the EIA Report. It is suggested to start the operational phase marine water quality impact monitoring 3 months after the commissioning of the expanded and upgraded San Wai STW.

4.5.1.13 Marine water samples and in situ measurement should be collected from all the sampling stations on 8 occasions at intervals of approximately 3 months during the operational phase of the project. On each occasion, marine water samples shall be collected every 2 hours for a 12-hour duration. When significant changes in the marine water quality are detected, the monitoring frequency should be increased as necessary until the cause for the changes is identified. The proposed water quality stations are discussed in Section 4.5.1.6 and are shown in Figure 4.1.

4.5.1.14 The monitoring programme can be discontinued after one year if there is no obvious changes in water quality beyond the prediction made in the EIA Report. The ET should be responsible for the operational phase marine water quality impact monitoring.

4.6 Operational Phase Effluent Quality Monitoring

4.6.1.1 To ensure the effectiveness of the proposed treatment process, monitoring of effluent quality in terms of pH, BOD, SS, TIN, NH3-N and E. coli is recommended. Monitoring of cadmium, copper, nickel, lead, mercury, chromium, zinc, PCBs and PAHs would also be included.

4.6.1.2 Toxicity testing shall be carried out on 8 occasions at intervals of approximately 3 months during the operational phase of the project for two marine species. One of the two marine species shall be selected from local environment. The representative species that will be chosen for this testing and the technical details of the testing method should be agreed and approved by EPD prior to the operation of the sewage treatment works.

4.6.1.3 It is proposed to monitor the effluent at the outlet chamber of the disinfection unit. The samples should be taken from 1m below the surface to ensure that the surface scum is not included in the sample. Laboratory analysis of effluent samples should follow the requirements given in Sections 4.5 above. A valid discharge licence should be obtained from EPD prior to the discharge of effluent from the project. The monitoring frequency and parameters specified in the discharge licence should be fully considered during the monitoring. The ET should seek approval from the DEP on all the monitoring requirements.

4.6.1.4 A valid discharge licence should be obtained from EPD prior to the discharge of effluent from the project. The effluent results reflect whether the effluent quality is in compliance with the discharge licence requirements. In case of non-compliance, suitable actions should be undertaken to notify the plant operator for the non-compliance and identify the sources of exceedance. The operating conditions of the treatment systems should be investigated. Corrective and remedial actions should be implemented to improve the effluent quality. The monitoring team should also increase monitoring frequency until the effluent quality is in compliance with the discharge licence requirements.

4.6.1.5 The non-compliance and propose preventive measures should be documented.

4.7 Quality Assurance/Quality Control of Laboratory Analysis

4.7.1.1 Detailed testing methods, pre-treatment procedures, instrument use, Quality Assurance/Quality Control (QA/QC) details (such as blank, spike recovery, number of duplicate samples per batch, etc.), detection limits and accuracy should be submitted to DEP for approval prior to the commencement of monitoring programme. The QA/QC results should be reported. EPD may also request the laboratory to carry out analysis of known standards provided by EPD for quality assurance. Additional duplicate samples may be required by EPD for inter laboratory calibration. Remaining samples after analysis should be kept by the laboratory for 3 months in case repeat analysis is required. If in-house or non-standard methods are proposed, details of the method verification may also be required to submit to DEP. In any circumstance, the sample testing should have comprehensive quality assurance and quality control programmes. The laboratory should prepare to demonstrate the programmes to DEP or his representatives when requested.

4.8 Data Analysis

4.8.1.1 Interpretation of the data generated from the marine water quality study will require statistical analysis at the following stages during the monitoring programme:

· After two sampling events in the baseline phase;
· On completion of the baseline period;
· After two sampling events in year 1 of the operational phase; and
· On completion of the sampling in year 1 of the operational phase.

4.8.1.2 Outcomes from data analysis will include:

· a detailed analysis of baseline water quality;
· an analysis of impacts from the outfall on marine waters; and
· comparison of results with relevant WQO's and baseline data.

4.9 Site Audits

4.9.1.1 Implementation of regular site audits is to ensure that the recommended mitigation measures shall be properly undertaken during the construction and operational phases of the project. It could also provide an effective control of any malpractices and achieve continual improvement of environmental performance on site.

4.9.1.2 The ET is responsible for carrying out the regular site audits. Site audits would include site inspections, compliance and conformance audits and environmental complaints.

Site Inspections

4.9.1.3 A programme for site inspections should be established defining the frequency, procedures and actions to be undertaken during the carrying out of site inspections. Site inspections should be based on the mitigation measures for water pollution control recommended in the EIA Report. In the event that the recommended mitigation measures are not fully or properly implemented, deficiency should be recorded and reported to the site management. Suitable actions are to be carried out to:

· Investigate the problems and the causes;
· Issue action notes to the Contractor which is responsible for the works;
· Implement remedial and corrective actions immediately;
· Re-inspect the site conditions upon completion of the remedial and corrective actions; and
· Record the event and discuss with the Contractor for preventive actions.

4.9.1.4 The ET should liaise closely with the Contractor to obtain information on the adopted working methods. Submission of method statements for the construction and operation activities by the Contractor could help the ET to accurately address the potential water quality impacts that may arise. Alternative working methods could be suggested to the Contractor in order to avoid adverse water quality impacts.

Compliance and Conformance Audits

4.9.1.5 Monitoring of effluent quality is required during the construction and operational phases of the Project. The monitoring should be carried out at the pre-determined discharge point. Compliance audits are to be undertaken to ensure that a valid discharge licence has been issued by EPD prior to the discharge of effluent from the project site. In addition, the monitoring frequency and parameters specified in the discharge licence should be fully considered during the monitoring. The audit results reflect whether the effluent quality is in compliance with the discharge licence requirements. In case of non-compliance, suitable actions should be undertaken to:

· Notify the site management for the non-compliance;
· Identify the sources of pollution;
· Check the implementation status of the recommended mitigation measures;
· Investigate the operating conditions of the sedimentation systems;
· Implement corrective and remedial actions to improve the effluent quality;
· Increase monitoring frequency until the effluent quality is in compliance with the discharge licence requirements; and
· Record the non-compliance and propose preventive measures.

4.9.1.6 Conformance audits are to ensure that the works carried out by the Contractor meet the statutory regulations and water pollution control requirements specified in the contractual documents. The Contractor should be responsible for design and implementation of the recommended mitigation measures. The ET should:

· Check the contractual documents which define the roles of the Contractor in water pollution control;
· Recommend necessary improvement works to the mitigation measures designed and undertaken by the Contractor;
· Evaluate the effectiveness of mitigation measures performed by the Contractor;
· Carry out ad hoc inspections of the Contractor's performance on water pollution control;
· Report to the site management for any non-conformance works; and
· Initiate actions to remedy any non-conformance works.

4.9.1.7 Good housekeeping on site is essential to the protection of water pollution. It is recommended to conduct audits to ensure that all the recommended elements are fully incorporated in the management system. It is recommended that pre-set checklists could be used to check the overall performance.

Environmental Complaints

4.9.1.8 A complaint hotline may be provided to the public for reporting of any unsatisfactory environmental conditions that could be created by the project. Procedures for complaint investigation should be developed in advance of commencement of the construction works. When a complaint on water pollution is received, the ET should:

· Record the date and time of receipt, and name and contact telephone number of the complainant;
· Report the complaint to the site management and initiate the investigation according to the information provided by the complainant;
· Discuss with the Contractor to verify the complaint and to identify the possible sources of pollution;
· Check the effectiveness and adequacy of relevant mitigation measures if the complaint is valid;
· Implement necessary corrective and remedial actions;
· Monitor the situation and take necessary follow-up action; and
· Inform the complainant the investigation results and actions taken for remedial works.

4.10 Water Quality Mitigation Measures

Construction Phase

4.10.1.1 Measures to minimise water quality impacts due to construction site runoff, wastewater from various construction activities, sewage from workforce and accidental spillage of chemicals are:

· Exposed stockpiles should be covered with tarpaulin or impervious sheets before a rainstorm occurs;
· The exposed soil surfaces should also be properly protected to minimise dust emission;
· The stockpiles of materials should be placed in the locations away from the drainage channel so as to avoid releasing materials into the channel;
· Wheel washing facilities should be provided at site exits to ensure that earth, mud and debris would not be carried out of the works areas by vehicles;
· Provision of site drainage systems and treatment facilities would be required to minimize the water pollution;
· A discharge licence needs to be applied from EPD for discharging effluent from the construction site;
· The treated effluent quality is required to meet the requirements specified in the discharge licence;
· Provision of chemical toilets is required to collect sewage from workforce. The chemical toilets should be cleaned on a regular basis;
· Wastewater generated from kitchens should be discharged to public foul sewers or collected in a temporary storage tank if connection to public foul sewers is not feasible;
· A licensed waste collector should be employed to clean the chemical toilets and temporary storage tank on a regular basis;
· Illegal disposal of chemicals should be strictly prohibited;
· Registration as a chemical waste producer is required if chemical wastes are generated and need to be disposed of. The Waste Disposal Ordinance (Cap 354) and its subsidiary regulations in particular the Waste Disposal (Chemical Waste) (General) Regulation should be observed and complied with for control of chemical wastes;
· Disposal of chemical wastes should be carried out in compliance with the Waste Disposal Ordinance. The Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes published under the Waste Disposal Ordinance should be used as a guideline for handing chemical wastes; and.
· The impact from accidental spillage of chemicals can be effectively controlled through good management practices.

Operational Phase

4.10.1.2 A contingency plan should be developed at the detailed design stage to deal with the emergency discharges that may occur during the operational stage of the project. It is recommended to include the following items in the contingency plan:

· Locations of the sensitive receivers in the vicinity of the emergency discharges at Deep Bay and Urmston Road;
· A list of relevant government bodies to be informed and to provide assistance in the event of emergency discharges. Information on key contact persons and telephone numbers should be included;
· Reporting procedures required in the event of emergency discharges; and
· Procedures listing the most effective means in rectifying the breakdown of San Wai STW, Urmston Road Tunnel or Ha Tsuen Pumping Station in order to minimise the discharge duration.