4 WATER QUALITY

4.1.1 Water quality impacts arising from the construction and operational activities would be minimised through implementation of suitable mitigation measures and good management practices. Contractual documents for the DBL project should incorporate the recommended mitigation measures for water pollution control.

4.1.2 Key water quality impacts arising from the DBL project would be mainly originated from the construction activities. Discharges of wastewater generated from the construction activities are subject to control under the WPCO. Wastewater should be adequately treated prior to the final discharge. The site management is responsible for applying a discharge licence from EPD for effluent discharges. The Environmental Team (ET) should be responsible for monitoring the quality of effluent discharged form the construction sites so as to ensure that a full compliance with the licence conditions is achievable. The pollutants should be controlled at source to minimise the potential water quality impacts to the water bodies downstream from the construction sites.

4.1.3 In addition to the monitoring of the quality of the discharges from construction sites, monitoring of water quality at selected local stream courses and in Deep Bay is included in this EM&A Manual.

4.1.4 In the Final EIA Report, it has been recommended that the DBL management authority should undertake the task to remove road sludge/pollutants from the end section of DBL at Ngau Hom Shek twice a week using a vacuum air sweeper/truck. This mitigation measure is to remove the pollutants at source and to prevent build-up of the pollutants on the road surface. In order to ensure that the road runoff after the cleaning operation would not be heavily polluted, monitoring of bridge runoff during the operational phase of the DBL project is included as part of the environmental monitoring and audit programme.

4.1.5 Site audits should be implemented to ensure that the mitigation measures and Best Management Practices (BMPs) recommended in the EIA are fully implemented during the construction phase of the DBL project.

4.2 Water Quality Parameters

Construction Phase Monitoring - Effluent Discharge from Construction Sites

4.2.1 Effluent discharged from the construction sites would enter the Groups B, C and D inland waters, Deep Bay WCZ and North Western WCZ. 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.

4.2.2 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.

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

Table 4.1 Water Quality Monitoring Data Record Sheet

Location / Discharge Point
Date
Start Time (hh:mm)
Weather
Conditions of the Treatment Systems
Discharge flow rate (m³/hr)
1. SS (mg/l)
2. pH (mg/l)
3. COD (mg/l)
4. (Other parameter)
5. (Other parameter)
6. (Other parameter)
Observed Construction Activities
Other Observations

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.

Construction Phase Monitoring - Local Stream Courses

4.2.4 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 courses is readily detected and timely action is taken to rectify the situation.

Construction Phase Monitoring - Coastal Waters of Deep Bay

4.2.5 Monitoring of suspended solids, pH and dissolved oxygen shall be undertaken to check compliance with the Water Quality Objectives. Some relevant data should also be measured/recorded, such as monitoring location/position, sampling time, water depth, water temperature, salinity, dissolved oxygen saturation, turbidity, weather conditions, sea conditions, tidal stage, and any special phenomena and work being carried out at the construction site near Ngau Hom Shek. The monitoring shall be carried out by the ET to ensure that any deterioration of water quality could be readily detected and action be taken in time to rectify the situation.

Operational Phase Monitoring - Road Runoff Monitoring

4.2.6 The monitoring shall be carried out by the ET to ensure that any deterioration of road runoff quality could be readily detected and action be taken in time to rectify the situation. Water samples shall be collected and analysed for the following most commonly found pollutants in highway runoff:

Total suspended solids
Total organic carbon
Chemical oxygen demand
Nitrate
Nitrite
Total Kjeldahl Nitrogen
Total phosphorus
Copper
Lead
Zinc

4.3 Monitoring Equipment

Dissolved Oxygen and Temperature Measuring Equipment

4.3.1 The instrument should be a portable, weatherproof dissolved oxygen-measuring instrument equipped with cable, sensor, comprehensive operation manuals, and use a DC power source. It should be capable of measuring:

dissolved oxygen level in the range of 0-20 mg/l and 0-200% saturation; and
temperature of 0 - 45 oC.

4.3.2 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).

Turbidity Measurement Instrument

4.3.3 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 and be complete with a cable (e.g. Hach model 2100P or an approved similar instrument).

Suspended Solids

4.3.4 A water sampler comprises a transparent PVC cylinder, with a capacity of not less than 2 litres, and can be effectively sealed with latex cups at both ends. The sampler should have a positive latching system to keep it open and prevent premature closure until released by a messenger when the sampler is at the selected water depth (e.g. Kahlsico Water Sampler or an approved similar instrument).

4.3.5 Water samples for suspended solids measurement shall be collected in high density polythene bottles, packed in ice (cooled to 4 oC without being frozen), and delivered to the laboratory as soon as possible after collection.

Salinity

4.3.6 A portable salinometer capable of measuring salinity in the range of 0-40 mg/l should be provided for measuring salinity of the water at each monitoring location.

4.3.7 pH meter (Hanna - HI 9024) or equivalent should be used to measure pH level of the water samples which should be collected in high density polythene bottles, packed in ice (cooled to 4 oC without being frozen), and delivered to the laboratory as soon as possible after collection.

Positioning Device

4.3.8 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

4.3.9 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

4.3.10 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.

4.3.11 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.

4.3.12 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.

4.3.13 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.

Runoff Sampling Equipment

4.3.14 Grab water samples shall be collected using automatic samplers. The sampling tube of the automatic sampler shall be connected to the outlet of the drainage down pipe from road drainage systems to collect water sample. A control device is required to switch on the automatic sampler when road runoff is detected at the outlet of the drainage down pipe.

4.3.15 Based on the findings in the University of New South Wales (UNSW) Research Report No. 204, pollutant concentrations in runoff were negligible after 20 to 30 minutes. The automatic sampler shall therefore be programmed to collect the first 20 to 30 minutes of bridge runoff.

4.4 Measurement and Laboratory Analysis

Construction Phase Monitoring - Effluent Discharge from Construction Sites

4.4.1 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.

Construction Phase Monitoring - Local Stream Courses

4.4.2 Water samples shall be collected at mid-depth at selected sampling locations in local stream courses. 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.

4.4.3 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.

Construction Phase Monitoring - Coastal Waters of Deep Bay

4.4.4 Water samples shall be collected at upper, middle and lower layers of the selected marine water monitoring stations. Dissolved oxygen, dissolved oxygen saturation, pH and turbidity shall be measured in-situ and analysis of suspended solids shall be carried out in a HOKLAS or other international accredited laboratory. Water samples of not less than 1000 ml should be collected at the monitoring stations for carrying out the laboratory SS determination. The detection limit should be 1 mg/L or better. The SS determination work 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.

Operational Phase Monitoring - Road Runoff

4.4.5 Each grab water sample collected shall be one litre in volume and 24 samples shall be collected per each rainstorm event in an automatic sampler. Each of the 6 grab samples shall be mixed to form a composite sample for analysis. There shall be in total 4 composite samples for each automatic sampler. After each rainstorm event, the water samples collected in the automatic sampler shall be delivered to laboratory for analysis within as short a time as possible. The water samples shall be cooled to 4°C without being frozen. The analysis shall commence within 24 hours after collection of the water samples. The water samples shall be analysed in a HOKLAS or other international accredited laboratory.

4.4.6 If a site laboratory is set up or a non-HOKLAS and non-international accredited laboratory is hired for carrying out the laboratory analysis, the laboratory equipment, analytical procedures, and quality control should be approved by the DEP. All the analysis shall be witnessed by the ER. The ET Leader shall provide the ER with one copy of the relevant chapters of the "Standard Methods for the Examination of Water and Wastewater" updated edition and any other relevant document for his reference.

4.4.7 For the testing methods of other parameters required by DEP, 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 shall 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 shall 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 shall have comprehensive quality assurance and quality control programmes. The laboratory shall prepare to demonstrate the programmes to DEP or his representatives when requested.

4.5 Monitoring Locations

Construction Phase Monitoring - Effluent Discharge from Construction Sites

4.5.1 Impact monitoring of effluent quality shall be carried out at representative discharge points where effluent from the construction sites is discharged into the local stream courses and channels after being treated in a wastewater treatment system. In view of the long distance of the DBL alignment, a number of effluent discharge points are proposed. Monitoring of the effluent quality should be carried out at these discharge points. Figure 4.1 shows the effluent discharge points / monitoring locations along the DBL alignment.

4.5.2 Runoffs and wastewater generated from the construction activities in different sections of the DBL alignment 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 these designated discharge points.

Construction Phase Monitoring - Local Stream Courses

4.5.3 The proposed monitoring locations in selected local stream courses are shown in Figure 4.2. Box culverts and diversion channels would be constructed to divert these stream courses. Water quality in these stream courses is potentially affected by the works. Control monitoring points are located upstream (S1, S3, S5, S7 and S9) of the construction sites and impact monitoring stations (S2, S4, S6, S8 and S10) are located downstream.

Construction Phase Monitoring - Coastal Waters of Deep Bay

4.5.4 DBL will be connected to the SWC at Ngau Hom Shek. Any discharges from the works area for SWC and from the end section of DBL near Ngau Hom Shek may cause water quality impacts to Deep Bay. Construction wastewater and site runoff generated from the SWC works area and the DBL construction site near Ngau Hom Shek would be treated before discharging into Deep Bay. The discharge location is shown in Figure 4.3. Under the SWC project, water quality monitoring in Deep Bay would be carried out. Figure 4.3 also shows the marine water monitoring stations for the SWC project. Since HyD is the management authority of the DBL and SWC projects, it is proposed that monitoring stations W1, W2, W11 and W12 should also be used to monitor the changes in water quality conditions due to the DBL and SWC projects in the region near Ngau Hom Shek. Depending on the tidal flow direction, the station located upstream of the works area or discharge location is the control station and the station located downstream is the impact monitoring station. The monitoring results at these four monitoring stations (W1, W2, W11 and W12) shall be presented in both the DBL and SWC EM&A reports.

4.5.6 Since the locations of W1, W2, W11 and W12 are within inter-tidal zone, monitoring at these two locations may be affected by the tidal conditions. When the water depth at these locations is too shallow, monitoring may not be feasible. If this case exists, the ET Leader shall propose updated monitoring locations for these two monitoring stations and seek approval from the IEC and DEP.

Operational Phase Monitoring - Road Runoff

4.5.7 Water samples shall be collected during rainstorm events at the outlets of the drainage down pipes located within the end section of DBL at Ngau Hom Shek. Since the types of fuel used by the vehicles travelling on the southbound carriageway and the northbound carriageway of the DBL alignment within this section may not be the same, there shall be in total 6 separate sampling points allocated on both sides the alignment. Three sampling points are to collect the runoff generated from the southbound carriageway whilst the other three are to collect the runoff generated from the northbound carriageway. The exact locations of the sampling points shall be determined based on the final road drainage layout plan to be prepared at the detailed design stage.

4.6 Baseline/Impact Monitoring and Remedial Actions

Construction Phase Monitoring - Effluent Discharge from Construction Sites

4.6.1 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. he 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.

4.6.2 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

Event	ET	Contractor	ER
Discharge licence requirement being exceeded by on sampling day	Repeat measurement on next day of exceedance to confirm findings Identify source(s) of impact Inform Contractor and EPD Check monitoring data, all plant, equipment and Contractor’s working methods Discuss mitigation measures with ER and Contractor Ensure mitigation measures are implemented Increase the monitoring frequency to daily until no exceedance of discharge licence’s requirement	Inform the Engineer and confirm notification of the non-compliance in writing Rectify unacceptable practice Check all plant and equipment Consider changes of working methods Propose mitigation measures to ER within 3 working days and discuss with ET and ER Implement the agreed mitigation measures	Discuss with ET and Contractor on the proposed mitigation measures Request Contractor to critically review the working methods Agree on the mitigation measures to be implemented Assess the effectiveness of the implemented mitigation measures
Discharge licence requirement being exceeded by more than two consecutive sampling days	Repeat measurement on next day of exceedance to confirm findings Identify source(s) of impact Inform Contractor and EPD Check monitoring data, all plant, equipment and Contractor’s working methods Discuss mitigation measures with ER and Contractor Ensure mitigation measures are implemented Increase the monitoring frequency to daily until no exceedance of discharge licence’s requirement for two consecutive days	inform the Engineer and confirm notification of the non-compliance in writing rectify unacceptable practice check all plant and equipment consider changes of working methods propose mitigation measures to ER within 3 working days and discuss with ET and ER implement the agreed mitigation measures slow down or stop all or part of the construction activities as instructed by the ER	discuss with ET and Contractor on the proposed mitigation measures request Contractor to critically review the working methods agree on the mitigation measures to be implemented assess the effectiveness of the implemented mitigation measures consider and instruct, if necessary, the Contractor to slow down or to stop all or part of the construction activities until no exceedance of the discharge licence’s requirement

Construction Phase Monitoring - Local Stream Courses

4.6.3 Baseline conditions of the selected local stream courses 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 all designated monitoring stations including control stations, 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.

4.6.4 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.

4.6.5 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.

4.6.6 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.

4.6.7 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.

4.6.8 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 4.3 Action and Limit Levels for Local Stream Water Quality

Parameter	Action Level	Limit Level
DO in mg/L (mid-depth)	5%ile of baseline data	4 mg/L or 40% saturation at 15 ^oC
SS in mg/L (mid-depth)	95%ile of baseline data or 120% of upstream control station’s SS on the same day of measurement	99%ile of baseline, or 130% of upstream control station’s SS on the same day of measurement
Turbidity in NTU (mid-depth)	95%ile of baseline data or 120% of upstream control station’s turbidity on the same day of measurement	99%ile of baseline or 130% upstream control station’s turbidity on the same day of measurement

Notes:

1. For DO, non-compliance of the water quality limits occurs when monitoring result is lower than the limits;

2. For SS and turbidity, non-compliance of the water quality limits occurs when monitoring result is higher than the limits.

Table 4.4 Event and Action Plan for Local Stream Water Quality

Event	Action
Event	ET Leader	IEC	ER	Contractor
Action Level being exceeded by one sampling day	Repeat in-situ measurement to confirm findings; Identify reasons for non-compliance and sources of impact; Inform IEC and Contractor; Check monitoring data, all plant, equipment and Contractor’s working methods; Discuss mitigation measures with IEC and Contractor; Repeat measurement on next day of exceedance.	Discuss with ET and Contractor on the mitigation measures; Review proposals on mitigation measures submitted by Contractor and advise the ER accordingly; Assess the effectiveness of the implemented mitigation measures.	Discuss with IEC on the proposed mitigation measures; make agreement on the mitigation measures to be implemented; Assess the effectiveness of the implemented mitigation measures.	Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment; Consider changes of working methods; Discuss with ET and IEC and propose mitigation measures to IEC and ER; Implement the agreed mitigation measures.
Action Level being exceeded by more than two consecutive sampling days	Repeat in-situ measurement to confirm findings; Identify reasons for non-compliance and sources of impact; Inform IEC and Contractor; Check monitoring data, all plant, equipment and Contractor’s working methods; Discuss mitigation measures with IEC and Contractor; Ensure mitigation measures are implemented; Prepare to increase the monitoring frequency to daily; Repeat measurement on next day of exceedance.	Discuss with ET and Contractor on the mitigation measures; Review proposals on mitigation measures submitted by Contractor and advise the ER accordingly; Assess the effectiveness of the implemented mitigation measures.	Discuss with IEC on the proposed mitigation measures; Make agreement on the mitigation measures to be implemented; Assess the effectiveness of the implemented mitigation measures.	Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment; Consider changes of working methods; Discuss with ET and IEC and propose mitigation measures to IEC and ER within 3 working days; Implement the agreed mitigation measures.
Limit Level being exceeded by one sampling day	Repeat in-situ measurement to confirm findings; Identify reasons for non-compliance and sources of impact; Inform IEC, Contractor and EPD; Check monitoring data, all plant, equipment and Contractor’s working methods; Discuss mitigation measures with IEC, ER and Contractor; Ensure mitigation measures are implemented; Increase the monitoring frequency to daily until no exceedance of Limit Level.	Discuss with ET and Contractor on the mitigation measures; Review proposals on mitigation measures submitted by Contractor and advise the ER accordingly; Assess the effectiveness of the implemented mitigation measures.	Discuss with IEC, ET and Contractor on the proposed mitigation measures; Request Contractor to critically review the working methods; Make agreement on the mitigation measures to be implemented; Assess the effectiveness of the implemented mitigation measures.	Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment; Consider changes of working methods; Discuss with ET, IEC and ER and propose mitigation measures to IEC and ER within 3 working days; Implement the agreed mitigation measures.
Limit Level being exceeded by more than two consecutive sampling days	Repeat in-situ measurement to confirm findings; Identify reasons for non-compliance and sources of impact; Inform IEC, Contractor and EPD; Check monitoring data, all plant, equipment and Contractor’s working methods; Discuss mitigation measures with IEC, ER and Contractor; Ensure mitigation measures are implemented; Increase the monitoring frequency to daily until no exceedance of Limit Level for two consecutive days.	Discuss with ET and Contractor on the mitigation measures; Review proposals on mitigation measures submitted by Contractor and advise the ER accordingly; Assess the effectiveness of the implemented mitigation measures.	Discuss with IEC, ET and Contractor on the proposed mitigation measures; Request Contractor to critically review the working methods; Make agreement on the mitigation measures to be implemented; Assess the effectiveness of the implemented mitigation measures; Consider and instruct, if necessary, the Contractor to slow down or to stop all or part of the marine work until no exceedance of Limit Level.	Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment; Consider changes of working methods; Discuss with ET, IEC and ER and propose mitigation measures to IEC and ER within 3 working days; Implement the agreed mitigation measures; As directed by the ER, to slow down or to stop all or part of the marine work or construction activities.

Construction Phase Monitoring - Coastal Waters of Deep Bay

4.6.9 To monitor the potential impacts on the coastal waters of Deep Bay, the DBL construction phase water quality monitoring could be implemented together with the SWC water quality monitoring. The baseline and impact monitoring to be undertaken by the SWC project would provide monitoring results to the ET of the DBL project for monitoring the impacts both from the SWC and the DBL construction activities near Ngau Hom Shek. The monitoring results at W1, W2, W11 and W12 shall be reported both in the SWC and DBL EM&A reports.

4.6.10 Baseline monitoring will be included in the SWC EM&A programme. Measurements at the monitoring stations W1, W2, W11 and W12 at mid-flood and mid-ebb tides shall be conducted for at least 4 weeks (3 days per week) prior to the commencement of marine works or construction activities to establish baseline conditions. The water quality parameters specified in Section 4.2 shall be measured. The ET Leader shall seek approval from the IEC and DEP on the final data set to be used as baseline reference.

4.6.11 During the course of the construction works, monitoring shall be undertaken three days per week, at mid-flood and mid-ebb tides, with sampling/measurement at the designated monitoring stations. 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.

4.6.12 The Action and Limit levels for water quality monitoring in Deep Bay are included in Table 4.5. 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 4.5 Action and Limit Levels for Water Quality Monitoring in Deep Bay

Parameters	Action	Limit Level
DO at surface, middle and bottom layers (mg/l)	Surface & Middle 5%-ile of baseline data for surface and middle layers Bottom 5%-ile of baseline data for bottom layer	Surface & Middle 4 mg/l or 1%-ile of baseline data for surface and middle layers Bottom 2 mg/l or 1%-ile of baseline data for bottom layer
Depth-averaged SS (mg/l)	95%-ile of baseline data or 120% of the SS levels measured at the upstream control station at the same tide of the same day	99%-ile of baseline or 130% of the SS levels measured at the upstream control station at the same tide of the same day and specific sensitive receiver water quality requirements (e.g. required suspended solids level for concerned sea water intakes)
Depth-averaged Turbidity (NTU)	95%-ile of baseline data or 120% of the turbidity levels measured at the upstream control station at the same tide of the same day	99%-ile of baseline or 130% of the turbidity measured at the upstream control station at the same tide of the same day

Notes:

1. "depth-averaged" is calculated by taking the arithmetic means of reading of all three depths.

2. For DO, non-compliance of the water quality limits occurs when monitoring result is lower than the limits.

3. For SS and turbidity, non-compliance of the water quality limits occurs when monitoring result is higher than the limits; and

4. All the figures given in the table are used for reference only and the EPD may amend the figures whenever it is considered as necessary.

Operational Phase Monitoring - Road Runoff

4.6.13 The road cleaning frequency proposed in the DBL EIA is twice a week. The minimum interval between two sampling events shall not be less than 4 days. The monitoring shall include 12 sampling/rainstorm events and cover the dry season period. A total of 6 sets of sampling data shall be collected during the first three months after the opening of DBL. The other 6 sets of sampling data shall be collected in month 4 to month 6 after the opening of DBL. Reporting of the monitoring results for these two periods is required. The monitoring results of each sampling event shall be submitted to EPD for information once the data is available.

4.6.14 There are no existing guidelines for controlling the discharge of road runoff into the Hong Kong waters. Since the main objective of implementing frequent cleaning of vehicle-generated pollutants from DBL is to prevent the pollutants from entering the Deep Bay waters and the mudflats, the pollution level of the bridge runoff with frequent cleaning should be lower than that of the normal road runoff from highways and expressways. With the implementation of road cleaning twice a week on end section of the DBL alignment, it is expected that the pollutant concentrations of the road runoff would be low.

4.6.15 A stormwater study will soon be carried out by EPD. Relevant information on the quality of highway runoff will be available by the time of the operational phase monitoring for this project. At present, it is proposed to use relevant overseas highway runoff data to form a set of reference criteria for comparison with the future monitoring data and to determine whether the runoff generated from DBL is within acceptable levels. The reference criteria shall be reviewed before the commencement of the operational phase monitoring to incorporate the latest findings from EPD's stormwater study.

4.6.16 Table 4.6 shows the general characteristics of highway runoff collected from various overseas studies. The ranges of pollutant concentrations are included in the last column of the table. Values in brackets are the averages of the lowest and the highest values. At present, there is no information to establish the baseline pollutant concentrations of the road runoff for the case without cleaning. The average pollutant concentrations for highway runoff shown in Table 4.6 are used as reference criteria to compare with the pollutant concentrations for the future road runoff. Table 4.7 summarizes the proposed criteria. The proposed action level and required action are also included in the table. The criteria should be reviewed and updated prior to the commencement of the monitoring based on the latest findings from EPD's stormwater study.

4.6.17 A review report shall be prepared by the Environmental Team after each period of monitoring that includes 6 sets of data to evaluate the road runoff quality and to determine if the proposed cleaning frequency is adequate to remove pollutants from the road section. The average daily number of vehicles using the northbound and southbound carriageways should be reported to give an indication of the effectiveness of road cleaning to different levels of traffic flows. All the monitoring results shall also be included in the EM&A report. If the monitoring results trigger the proposed action level, the cleaning frequency shall be increased to remove the vehicle-generated pollutants from the end section of DBL at Ngau Hom Shek.

Table 4.6 Characteristics of Highway Runoff

Parameter	Data Source				Concentration Range
Parameter	Driscoll et al.¹(1990) Highways with more than 30,000 Vehicles/Day	US EPA² (1983)	Barrett et al.³ (1995)	Drapper et al.⁴ (2000)	Concentration Range
Total suspended solids (mg/L)	142	100	19 – 131	60 – 135	19 – 142 (81)
Total organic carbon (mg/L)	25	-	-	-	25 (25)
Chemical oxygen demand (mg/L)	114	65	-	-	65 – 114 (90)
Nitrite and nitrate (mg/L)	0.76	0.68	Only NO₃-N was measured (0.28 – 1.03)	-	0.68 – 0.76 (0.72)
Total Kjeldahl Nitrogen (mg/L)	1.83	-	-	1.7 – 11	1.7 – 11 (6.4)
Total phosphorus (mg/L)	0.4 (phosphate)	0.315	0.1 – 0.33	0.19 – 1.8	0.1 – 1.8 (0.95)
Copper (mg/L)	0.054	0.034	0.007 – 0.034	0.03 – 0.34	0.007 – 0.34 (0.174)
Lead (mg/L)	0.4	0.144	0.007 – 0.05	0.08 – 0.62	0.007 – 0.62 (0.31)
Zinc (mg/L)	0.329	0.160	0.022 – 0.208	0.15 – 1.85	0.022 – 1.85 (0.94)

Notes:

1. Discoll, E. D., Shelley, P. E., and Strecker, E. W. (1990). "Pollutant loadings and impacts from highway stormwater runoff. Vol. I: Design procedure." Tech. Rep. No. FHWA-RD-88-007. Prepared for the Fed. Hwy. Admin., Washington, D. C.
2. Barrett, M. E., Irish Jr, L. B., Malina Jr., H. F., and Charbeneau, R. J. (1998). "Characterization of Highway Runoff in Austin, Texas, Area. " Journal of Environmental Engineering, Vol. 124, No. 2, pp 131137.
3. Barrett, M. E., Malina, J. F., Charbeneau, R. J., and Ward, G. H. (1995). "Characterisation of highway runoff in the Austin, Texas area." Ctr. For Res. In Water Resour., Bureau of Engrg. Res., University of Texas at Austin, Austin, Tex.
4. Drapper, D., Tomlinson, R., and Williams, P. (2000). "Pollution concentrations in road runoff: Southeast Queensland Case Study." Journal of Environmental Engineering, ASCE, Vol. 126, No. 4, 313-320.
5. The value in bracket represents an average of the lowest and highest values.

Table 4.7 Proposed Criteria to be Used for Determination of Cleaning Frequency, Action Level and Action

Parameter	Reference Criteria for Determination of Cleaning Frequency¹	Action Level	Action
Total suspended solids (mg/L)	81	3 consecutive monitoring with the same parameter (1 or more than 1 parameter) exceeded the criteria	Increase 1 cleaning event per week
Total organic carbon (mg/L)	25
Chemical oxygen demand (mg/L)	90
Nitrite and nitrate (mg/L)	0.72
Total Kjeldahl Nitrogen (mg/L)	6.4
Total phosphorus (mg/L)	0.95
Copper (mg/L)	0.174
Lead (mg/L)	0.31
Zinc (mg/L)	0.94

Note:

1. The criteria presented in this table are for reference only and will be reviewed using latest available information before the commencement of the road runoff monitoring.

4.7 Site Audits

4.7.1 Implementation of regular site audits is to ensure that the recommended mitigation measures are to be properly undertaken during the construction phase of the DBL project. 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

4.7.2 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 Final EIA. 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.

4.7.3 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

4.7.4 Monitoring of effluent quality is required during the construction phase 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.

4.7.5 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.

4.7.6 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

4.7.7 A complaint hotline may be provided to the public for reporting of any unsatisfactory environmental conditions that could be created by the DBL 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.

Continual Improvement

4.7.8 Implementation of mitigation measures safeguards the aquatic environments in the vicinity of the DBL alignment and is one of the important components for improvement of water pollution control. This component needs to be integrated with other components to form an integral system for achieving water pollution control. These include:

commitment to control water pollution;
good planning;
staff training;
checking and corrective actions; and
management review.

4.7.9 The integral system should be implemented in a systematic manner. Continual improvement of water pollution control would be achieved through the implementation of the integral system.

4.8 Water Quality Mitigation Measures

4.8.1 Mitigation measures for control of water pollution have been recommended in the Final EIA. The Contractor should be responsible for the design and implementation of these measures. The recommended mitigation measures and guidelines to reduce the potential water quality impacts during the construction and operational phases of the DBL project are summarised as follows:

Construction Phase

Local Stream Courses, Pipeworks and Drains

Local stream courses should be realigned or diverted in the sections where the proposed road alignment intersects with the local stream courses to ensure that there would be no discontinuity of flows downstream from the construction sites.
Box culverts and diversion channels should be constructed to divert the stream flows downstream.
Supporting columns and piers for the elevated sections of the DBL should be located away from existing stream courses as far as possible.
The design of the diverted sections of the stream courses should minimise loss of flow section and avoid generating unstable flow conditions.
The construction period for re-alignment or diversion of stream courses should be shortened as far as possible through a better coordination with the other DBL construction activities.
The contract documents should clearly specify the responsibilities of the Contractor to ensure the runoff from the works area should pass through silt traps and suitable sedimentation facilities prior to discharging into stream courses.
A construction site drainage layout and management plan should be developed by the Contractor to detail the procedures for control of construction site runoff. The plan should be submitted to the ET prior to the commencement of the DBL construction works to ensure a better site management and control of surface runoff on site.
The existing pipes, which would be affected by the DBL project due to the increased runoff from DBL, should be upsized to increase the pipe capacity.

Excavation and Filling

A discharge license from EPD for discharge of effluent should be obtained. The quality of the discharged effluent in terms of pH, suspended solids, chemical oxygen demand and other parameters as required should comply with the license conditions.
The Contractor should develop a construction site drainage layout and management plan with the consideration of the mitigation measures recommended in the ProPECC PN1/94.
In areas where extensive excavation and filling are carried out, temporary earth bunds should be built. Sand bags may be used to confine the runoff or wastewater generated from the construction activities.
Excavation works should be minimised in rainy season.
Open stockpiles of construction materials and dusty materials should be covered with tarpaulin during rainstorms. These materials should not be placed near the stream courses. This avoids the release of materials into the stream water.
The carrying out of trench and hole digging should be in short sections. Trenches and holes should be immediately back-filled after the completion of a section of works to minimise the inflow of rainwater during rainstorms.
To prevent storm runoff from washing across exposed soil surface, intercepting channels should be provided. It is recommended to pave haul roads with concrete and protect temporary access roads using crushed stone or gravel. The exposed slope surfaces should be lined or hydroseeded.
Provision of a detention tank in a stream course, which traverses the Hung Shui Kui New Development Area.
Drainage systems should be provided on site to collect all the contaminated runoff. Installation of sediment basin/trap and/or oil/grit separator is also recommended to reduce the pollution levels of contaminated runoff.

Construction of Foundation and Road Sections

Recommendations on water quality impact mitigation measures outlined in ProPECC PN1/94 – Construction Site Drainage should be adopted.
The wastewater generated from bored pile foundation construction and related activities should be collected and recycled.
Recommended mitigation measures against release of muddy wastewater from bored piling sites located approximately 15m to the northwest of Deep Bay Road into Deep Bay mudflat are:
A row of interlocking sheetpiles should be installed to essentially fence off the area from the nearby stream course; and
A wastewater treatment system comprising of chemical coagulation, sedimentation and pH control processes should be installed on site to treat the wastewater generated from the bored piling works.
The above proposed mitigation measures should be included in the contract and reflected in the tender drawings.
The Contractor should submit a construction site drainage layout and management plan prior to the commencement of the DBL construction works.
The treated effluent could be used for vehicle washing, dust suppression and general cleaning.
Bentonite slurries used in bore-piling works or diaphragm wall construction should be reconditioned and reused wherever practicable. A licensed waste collector should be deployed for collection and disposal of the used bentonite slurries.
Adequate surface channels should be constructed along the site boundaries to avoid release of surface and storm runoffs out of the sites.
The channel system to collect the runoffs in the construction sites should be well designed prior to the commencement of the site formation works.
Provision of drains at the lowest points of the sites could effectively collect the runoff. Silt and sand traps, which remove large soil particles in the runoffs, should be provided in the channels. Regular maintenance and cleaning of the channels would ensure that the channel system is in good conditions and is not obstructed by sediments.
Vehicle wheel washing facilities should be provided at all site exits to avoid the escape of soil and dirt from the construction sites.
Wastewater generated from the vehicle wheel washing facilities should be recycled wherever practicable. Excess wastewater should be transferred to suitable treatment systems for removal of suspended solids.
Wastewater generated from washing of concrete lorry mixers should be pre-treated by discharging into a sedimentation pit, which provides a quiescent environment for the concrete particles to settle and consolidate. The upper layer water in the sedimentation pit with low concentrations of concrete particles should be further treated to the standards acceptable for final discharge. The concrete wastes deposited on the bottom of the pit should be removed regularly.
Covers should be provided to the newly constructed manholes to prevent any kinds of wastewater from entering into the drainage systems during the construction phase.
Pipes connected to the manholes should be temporarily sealed to avoid debris and construction materials get into the drainage systems.
A wastewater treatment system comprising of chemical coagulation, sedimentation and pH control processes should be used to treat the site runoffs and the wastewater generated from various construction activities.

On Site Sewage Generation

Chemical toilets should be provided on site for collection and temporary storage of sewage. Alternatively, sewage storage tank should be provided. The collected sewage should be tinkered away by a licensed waste collector for off-site disposal.

Water quality impacts would be minimised through implementation of Best Management Practices. The major areas to be considered include:

Clean Site Policy

Top management commitment
Review of policy statement and effectiveness of performance periodically
Improvement in environmental awareness
Inclusion of mitigation measures in contractual documents

Design and Planning

Site planning appropriate to site conditions
Re-alignment of the existing streams
Minimisation of storm water runoff
Adequacy of storm drain and grit/sand removal facilities
Measures to deal with generation of sewage
Treatment facilities to handle site discharges

Environmental Team and Site Management

Monitoring and inspection of the proper implementation of mitigation measures
Identification of unforeseen pollution problems and needs for improvement
Improvement of the environmental awareness of the working parties

Good Housekeeping

Provision of designated areas for storage of raw materials, chemicals and toxic substances
Control and keeping records of raw materials, chemicals and toxic substances being delivered to and out of the construction sites
Provision of control areas for equipment maintenance and repair
Provision of adequate sewage collection facilities at convenient locations
Registration as a “Chemical Waste Producer” if necessary and provision of proper storage, labelling and disposal of chemical wastes generated from the construction activities
Collection of site debris and solid wastes on a regular basis
Notification to all working parties of no illegal disposal of wastewater and chemical wastes
Minimisation of the volume of wastewater generated from dust suppression activities and unattended water faucets
Provision of treatment facilities including sediment removal facilities and oil/grit separator to control site discharges to the standards in compliance with the requirements specified in the discharge licence

Monitoring and Audit

Monitoring of the discharged effluent quality at the final discharge points
Laboratory analysis of pH, COD, suspended solids and other parameters as specified in the discharge licence
Checking compliance with the requirements specified in the discharge licence

A sample data record sheet is shown in Appendix B for reference.

Operational Phase

Storm Runoff from Road Sections

During the planning and design stages of the project, storm drain systems should be suitably planned to receive storm runoff from the DBL building facilities and road alignment.
Vacuum air sweepers/trucks should be deployed to remove the pollutants deposited on the road surface in the section near Ngau Hom Shek with a cleaning frequency of twice a week during the low traffic flow condition. The cleaning path of the vacuum air sweeper should mainly cover the region about 1 to 2 m from the road kerb.
Standard HyD road gullies with silt traps should be installed in the road drainage systems to remove the residual grit, particulate matter and pollutants in road runoff.
Regular cleaning of rubbish and sediment from the drainage systems following the normal highway maintenance practices is required to maintain the normal operation of the systems at all times.
Oil and grease interceptors would be incorporated as part of drainage system in areas where vehicles may be parked, i.e. vehicle recovery and weighting station.

Accidental Spillage of Chemicals During Accidents

The following issues require to be considered and appropriate action taken on a case by case basis:

measures to prevent the potential pollution to the local stream courses and the downstream water body in case of an accident;
requirements to inspect the drainage systems to ensure that the channels or drain pipes are in normal function;
procedures and guidelines to deal with different categories of spillage;
actions to inspect and monitor the water quality of the nearby receiving water body after an accident;
provision of pollution control equipment; and
actions to restore the affected water body.