Table of contents

 

1        INTRODUCTION.. 1

1.1         Background. 1

1.2         Project Descriptions. 1

1.3         Project Programme. 2

1.4         Purpose of this Environmental Monitoring and Audit (EM&A) Manual 2

1.5         Structure of EM&A Manual 3

2        Project Organization.. 4

2.1         Introduction. 4

2.2         Project Proponent 4

2.3         The Contractor 4

2.4         Engineer’s Representatives (ER) 4

2.5         Independent Environmental Checker (IEC) 5

2.6         Environmental Team (ET) 5

3        Air quality.. 7

3.1         Introduction. 7

3.2         Monitoring Parameters. 7

3.3         Monitoring Equipment 7

3.4         Monitoring Requirements. 7

3.5         Monitoring Location. 10

3.6         Placement of Equipment 10

3.7         Baseline Monitoring. 11

3.8         Impact Monitoring. 11

3.9         Air Quality Performance Limit 12

3.10       Event and Action Plan. 12

3.11       Mitigation Measures. 12

4        Noise.. 14

4.1         Introduction. 14

4.2         Monitoring Parameters. 14

4.3         Monitoring Equipment 14

4.4         Monitoring Requirement 15

4.5         Monitoring Location. 15

4.6         Baseline Monitoring. 16

4.7         Impact Monitoring. 16

4.8         Noise Performance Limit 16

4.9         Event and Action Plan. 16

4.10       Mitigation Measures. 17

5        Water quality.. 18

5.1         Introduction. 18

5.2         Construction Phase EM&A.. 18

5.3         Operational Phase EM&A (Effluent Quality) 20

5.4         Operational Phase EM&A (Marine Water Quality) 21

5.5         Monitoring Equipment 22

5.6         Water Quality Performance Limit 25

5.7         Event and Action Plan. 26

5.8         Mitigation Measures. 26

6        Terrestrial Ecology.. 28

6.1         Introduction. 28

6.2         Mitigation Measures. 28

7        marine Ecology.. 29

7.1         Introduction. 29

7.2         Mitigation Measures. 29

8        FisherIES. 30

8.1         Introduction. 30

8.2         Mitigation Measures. 30

9        Waste Management and Land contamination.. 31

9.1         Introduction. 31

9.2         EM&A Requirement 31

9.3         Waste Management Plan. 31

9.4         Site Audit 32

9.5         Mitigation Measures. 32

10     landscape and visual.. 33

10.1       Introduction. 33

10.2       Mitigation Measures. 33

10.3       Mitigation Measures. 34

11     Built heritage.. 35

11.1       Introduction. 35

11.2       EM&A Requirement 35

11.3       Mitigation Measures. 35

12     site environmental audit.. 36

12.1       Introduction. 36

12.2       Site Inspection. 36

12.3       Compliance with Legal and Contractual Requirements. 37

12.4       Environmental Complaints. 37

13     reporting.. 39

13.1       Introduction. 39

13.2       Baseline Monitoring Report 39

13.3       EM&A Report 40

13.4       First EM&A Report 40

13.5       Subsequent EM&A Reports. 42

13.6       Quarterly EM&A Summary Reports. 44

13.7       Final EM&A Report 46

13.8       Data Keeping. 48

13.9       Interim Notification of Environmental Quality Limit Exceedances. 48

14     conclusion.. 49

 


 

LIST OF TABLES

 

Table 3.1         Proposed Dust Monitoring Stations

Table 3.2         Action and Limit Levels for Air Quality

Table 4.1         Proposed Construction Noise Monitoring Locations

Table 4.2         Action and Limit Levels for Noise

Table 5.1         Marine Water Monitoring Locations in Construction Phase

Table 5.2         Overall Summary of Monitoring Requirements in Construction and Operational Phases

Table 5.3         Analytical Methods and Detection Limits for Marine Water Samples

Table 5.4         Action / Limit Levels for Water Quality

 

 

 

LIST OF FIGURES

 

Figure 1-1        Layout Plan of Proposed Sewerage Works in Po Toi O

Figure 2-1        Project Organisation for Environmental Works

Figure 3-1        Location of Air and Noise Monitoring Stations

Figure 5-1        Location of Water Monitoring Stations

Figure 11-1      Location of Built Heritage Resources

 

 

 

LIST OF APPENDICES

 

Appendix A    Implementation Schedule of Recommended Mitigation Measures

Appendix B    Sample Data Sheet

Appendix C    Event and Action Plan

Appendix D    Interim Notifications of Exceedances

 

 

 

1                         INTRODUCTION

1.1                   Background

1.1.1             The proposed sewerage works in Po Toi O is an environmental enhancement project that aims to improve environmental hygiene of the Po Toi O area.

1.1.2             Po Toi O is located in the southern part of Sai Kung District, next to Clear Water Bay. There is a small settlement called Po Toi O village around the bay. There is currently no public sewerage system for the village. Sewage and wastewater generated by local residents and local restaurants are treated by septic tanks/soakaway system (STS).

1.1.3             Provision of proper sewerage system to unsewered villages is a general government policy. Without centralized public sewage treatment facility, villagers have to regularly desludge the STS to maintain the cleaning performance and to avoid overflow of sewage. However, the desludging process may bring along potential hygiene and associated odour issues. Under the Port Shelter Sewerage Master Plan (SMP), Drainage Services Department (DSD) has proposed sewerage works at Po Toi. In addition to improving local hygiene conditions and removing associated odour problem, the provision of sewerage is a preventive measure to avoid potential environmental problems due to insufficient desludging or structural defect of the STS. This can also relieve villagers’ burden to maintain their STS (e.g. desludging).

1.1.4             The proposed sewerage works at Po Toi O comprise sewage collection, treatment and disposal facilities at Po Toi O under Port Shelter Sewerage, Stage 3 – Sewerage Works at Po Toi O (hereinafter referred to as “the Project”). The location and details of the facilities are illustrated in Figure 1-1.

1.1.5             Cinotech Consultants Ltd. (Cinotech) has been commissioned by DSD in January 2014 to conduct an environmental impact assessment for the Project in order to investigate the environmental acceptability during construction and operation of the proposed sewerage works. Black & Veatch Hong Kong Limited (hereafter called “the Engineer”) is the consulting engineer employed by DSD to design the proposed sewerage facilities in this Project, among other tasks. Urbis Limited and LWK & Partners (HK) Limited provided expert input in landscape and visual impact and built heritage impact assessments respectively.

1.2                   Project Descriptions

1.2.1             The Project mainly comprises the following works:

                                  i.          Provision of village sewerage to the unsewered areas of Po Toi O. The works involve construction of about 800m of gravity sewers and 400m of rising mains;

                                ii.          Construction of a local sewage treatment plant (STP) with Average Dry Weather Flow (ADWF) of about 139m3/day; and

                              iii.          Construction of a submarine outfall of about 385m in length.

 

1.2.2             The Project consists of the following designated projects under Part I, Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO):

l   Item Q.1 – A sewage treatment plant and portion of sewer alignments in a conservation area;

l   Item C.12 (a) (v) and (vii) – A dredging operation which is less than 500m from the nearest boundary of an existing fish culture zone and coastal protection area; and

l   Item F.6 – A submarine sewage outfall.

1.3                   Project Programme

1.3.1             The construction works for this Project are expected to commence in mid-2017 and complete in 2021 with one more year for defect correction.

1.4                   Purpose of this Environmental Monitoring and Audit (EM&A) Manual

1.4.1             The purpose of this EM&A Manual (hereafter called the “Manual”) is to guide the establishment of an EM&A programme to assure compliance with the standards and predictions in the EIA study involving the construction and operation of Po Toi O Sewage Treatment Works (PTOSTW). The environmental performance will be regularly monitored and audited for evaluating the effectiveness of the recommended mitigation measures and to investigate any further need for additional mitigation measures or remedial action.

1.4.2             This EM&A Manual is prepared based on the findings and recommendations in the EIA and with reference to the requirements stipulated in Annex 21 Technical Memorandum under the Environmental Impact Assessment Ordinance (EIAO-TM):

(i)                 To propose EM&A programme to monitor the environmental performance of the project

(ii)               To check the implementation status of mitigation measures to minimize construction and operational impacts on the environment

(iii)             To identify the need for additional mitigation measures

(iv)             To advise the responsibilities of different parties involved in the project and communication flow among them

(v)               To detail monitoring requirements (locations, environmental parameters, frequency, duration) before and during the construction period and in the operational period

(vi)             To propose monitoring equipment required and quality assurance

(vii)           To determine action and limit levels of each environmental parameter based on the legislative criteria and standards for compliance checking

(viii)         To set up event and action plans for remedial actions if exceedance of compliance is identified

(ix)             To devise procedures for handling complaint/consultation

(x)               To detail reporting requirement

1.5                   Structure of EM&A Manual

1.5.1             This EM&A Manual comprises the following Chapters:

l   Ch.1  Introduction

l   Ch. 2  Project Organization

l   Ch. 3  Air Quality

l   Ch. 4  Noise

l   Ch. 5  Water Quality

l   Ch. 6  Terrestrial Ecology

l   Ch. 7  Marine Ecology

l   Ch. 8  Fisheries

l   Ch. 9  Waste Management and Land Contamination

l   Ch. 10  Landscape and Visual

l   Ch. 11  Built Heritage

l   Ch. 12  Site Environmental Audit

l   Ch. 13  Reporting

l   Ch. 14  Conclusion


2                    Project Organization

2.1         Introduction

2.1.1        The implementation of the recommended EM&A programme requires participation of relevant parties in a correlative and collaborative manner. The project organization and lines of communication with respect to the recommended EM&A works are shown in Figure 2-1. The roles and responsibilities of the key EM&A programme participants involved are described in the following sections.

2.2         Project Proponent

2.2.1        The Project Proponent (Drainage Services Department) shall employ the Independent Environmental Checker (IEC) to audit and check the EM&A works carried out by the Environmental Team (ET).

2.3         The Contractor

2.3.1        The Contractor implies all construction contractors and sub-contractors working on the Project Site (within work boundary demarcated in Figure 1-1). He should:

(i)                 Engage the ET to carry out EM&A works

(ii)               Notify the ET the construction activities that may have environmental concern

(iii)             Participate in the site inspection carried out by the ET and to rectify any environmental deficiency identified

(iv)             Propose and implement necessary measures to mitigate any exceedance in Action/Limit Levels recorded in accordance to the Event/Action Plans

(v)               Investigate complaints according to the agreed procedures

2.4         Engineer’s Representatives (ER)

2.4.1        The ER shall be responsible to oversee the construction work of all contractors to ensure that the contract specifications are met. He should:

(i)                 Supervise the Contractor’s activities to ensure that they comply with the requirements in the EIA, EM&A Manual, Environmental Permit (EP) and the contract specifications

(ii)               Follow the agreed procedures in the Event/Action Plan in case of any exceedance and instruct the Contractor to carry out remedial actions

(iii)             Participate in joint site inspections and audits undertaken by the ET

(iv)             Investigate complaints according to the agreed procedures and instruct the Contractor to follow up

(v)               Assist the ET in implementation of EM&A programme when required

2.5         Independent Environmental Checker (IEC)

2.5.1        The IEC shall be appointed by the Project Proponent to audit and verify the EM&A works carried out by the ET and to oversee the environmental performance of the Project site. He shall not have any association with the Contractor, ER or ET. The IEC should possess at least 7 years of experience in EM&A. The IEC should:

(i)                 Review and verify EM&A Reports and submissions for EP prepared by the ET and advise for improvement

(ii)               Audit and confirm the validity and accuracy of monitoring activities and results. He may carry out random sample check and audit on monitoring data and sampling procedures, etc

(iii)             Audit the EIA recommendations and requirements against the status of implementation of environmental protection measures on site

(iv)             Review the implementation status and effectiveness of mitigation measures onsite and ensure that they are carried out properly

(v)               Conduct monthly and ad-hoc site inspections

(vi)             Investigate complaints according to the agreed procedures

(vii)           Review the proposal of mitigation measures by the Contractor in an event of exceedance according to the Event/Action Plan

2.6         Environmental Team (ET)

2.6.1        The ET shall be led and managed by the ET Leader. The ET Leader shall be an independent party from the Contractor and have relevant professional qualifications, or have sufficient relevant EM&A experience subject to the approval of the Engineer’s Representative (ER). The ET Leader shall possess at least 7 years of experience in EM&A and/or environmental management. The ET should carry out the EM&A programme and to check the Contractor’s compliance with the environmental protection requirements in the EIA, EM&A Manual and EP. The ET should:

(i)                 Set up monitoring stations to carry out monitoring works, statistical analysis and compliance checking against legislative standard and guidelines

(ii)               Repeat field measurement in case of exceedance and propose mitigation measures for improvement

(iii)             Conduct weekly and ad-hoc site inspections to audit the Contractor’s site practice on pollution prevention and the effectiveness and adequacy of mitigation measures

(iv)             Advise the Contractor rectification work required when environmental deficiency is identified

(v)               Prepare monthly and quarterly EM&A reports to summarise environmental performance and to anticipate future key issues

(vi)             Review and comment on work schedule and methodology as necessary

(vii)           Support the Contractor for submissions required under the EP

(viii)         Investigate complaints and propose corrective measures according to the agreed procedures

(ix)             Liaise with the IEC on environmental performance matters and timely submission of all EM&A proforma for IEC’s approval

2.6.2        The ET Leader shall keep a contemporaneous logbook for recording each and every instance or circumstance or change of circumstances that may affect the compliance with the recommendations of the EIA report. This logbook shall be kept readily available for inspection by the IEC, and the Director of Environmental Protection (DEP) or his authorised officers.


3                    Air quality

3.1         Introduction

3.1.1        Major air quality impact in construction phase would arise from excavation of slope at the proposed sewage treatment plant. With implementation of dust suppression measures, it is anticipated that the dust impact would be acceptable. Regular air quality monitoring should be conducted at representative ASRs to ensure that relevant air quality standard can be met.

3.1.2        During the operational phase of the Project, odour will be generated from the operation of the proposed sewage treatment plant. With enclosure of odour sources underground, deodourization before exhaust into the atmosphere and adoption of enclosed container during transportation, odour impact is expected to be acceptable. According to the modelled results in the EIA Report, the odour levels at representative ASRs are far below the EIAO TM assessment criterion. Therefore, operational phase air quality monitoring is considered unnecessary.

3.1.3        This section outlines the requirements, methodology, equipment and locations for monitoring air quality impacts during the construction phase of the Po Toi O STW.

3.2         Monitoring Parameters

3.2.1        The ET shall evaluate the construction air quality impact by conducting 1-hour and 24-hour Total Suspended Particulates (TSP) measurements.

3.3         Monitoring Equipment

3.3.1        1-hour and 24-hour TSP levels will be measured in accordance to the standard high volume sampling method as set out in the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix A. 

3.3.2        Other than using high volume sampler, 1-hour TSP levels can be measured alternatively by direct reading from portable dust meters upon approval from ER. The meters should be capable of producing comparable results as that by the high volume sampling method, to indicate short event impacts.

3.4         Monitoring Requirements

High Volume Sampler

3.4.1        The ET shall provide sufficient number of high volume samplers (HVSs) for measurement at different ASRs during each monitoring. The HVSs shall comply with the following specifications for carrying out the 1-hour and 24-hour TSP monitoring:

(a)           0.6 - 1.7 m3 per minute adjustable flow range;

(b)           equipped with a timing / control device with +/- 5 minutes accuracy for 24 hours operation;

(c)           installed with elapsed-time meter with +/- 2 minutes accuracy for 24 hours operation;

(d)          capable of providing a minimum exposed area of 406 cm2;

(e)           flow control accuracy: +/- 2.5% deviation over 24-hour sampling period;

(f)            equipped with a shelter to protect the filter and sampler;

(g)           incorporated with an electronic mass flow rate controller or other equivalent devices;

(h)           equipped with a flow recorder for continuous monitoring;

(i)             provided with a peaked roof inlet;

(j)             incorporated with a manometer;

(k)           able to hold and seal the filter paper to the sampler housing at horizontal position;

(l)             equipped with easily changeable filter; and

(m)         capable of operating continuously for a 24-hour period.

3.4.2        Clearly labelled calibration kit and filter papers shall also be provided. The HVSs should be equipped with an electronic mass flow controller and be calibrated against a traceable standard at regular intervals.

3.4.3        Calibration should first be conducted after installing the HVSs and repeated on bi-monthly basis. The transfer standard shall be traceable to the internationally recognised primary standard and be calibrated annually. The concern parties such as IEC shall properly document the calibration data for future reference. All the data should be converted into standard temperature and pressure condition.

3.4.4        The flow-rate of the sampler before and after the sampling exercise with the filter in position shall be verified to be constant and be recorded in the data sheet in Appendix B.

Direct Reading Meter

3.4.5        If the ET prefers to adopt direct reading method for 1-hour TSP, he should provide adequate support to the IEC for verifying the capacity of the meter as with the HVSs in obtaining comparable measurements. The meter shall be calibrated at regular intervals in accordance to the specification in the manufacturer’s manual. The calibration certificates shall be available to the IEC for checking upon request. The validity and accuracy of the meter shall also be tested against the results by the HVS periodically. Sample data sheet is available in Appendix B.

Collection of Wind Data

3.4.6        For recording wind speed and wind direction, the ET shall install wind data monitoring equipment near the dust monitoring locations. The installation location shall be proposed by the ET and agreed with the IEC. The installation and operation of the equipment shall meet the following criteria:

(a)           The wind sensors should be installed 10 m above ground so that they are clear of obstructions or turbulence caused by buildings.

(b)           The wind data should be captured by a data logger. The data shall be downloaded for analysis at least once a month.

(c)           The wind data monitoring equipment should be re-calibrated at least once every six months.

(d)          Wind direction should be divided into 16 sectors of 22.5 degrees each.

3.4.7        If agreed by the ER and the IEC, the ET may obtain wind data using alternative method.

Laboratory Testing

3.4.8        Filter paper to be placed in the HVSs should have a size of 8" x 10" and be labelled before sampling. It should be clean without pinholes, and be conditioned in a humidity-controlled chamber for over 24-hours and be pre-weighed before use for the sampling.

3.4.9        After air is passed through the HVSs, the filter paper inside will be loaded with dust. It shall be collected inside a clean and tightly sealed plastic bag for transporting to a laboratory. It shall be reconditioned in the humidity-controlled chamber followed by accurate weighing by an electronic balance with accuracy up to 0.1 mg. The balance shall be regularly calibrated against a traceable standard.

3.4.10    All samples should be kept in good condition for 6 months before disposal.

3.4.11    The testing laboratory should be HOKLAS accredited. It should be clean and can maintain a stable temperature and humidity. Measuring and conditioning instruments should be available for handling the dust samples. It should be able to carry out result analysis, equipment calibration and maintenance.

3.4.12    If a site or non-HOKLAS laboratory will be responsible for conducting the testing, the laboratory equipment shall be approved by the ER and the measurement procedures shall be witnessed by the IEC. Any measurement performed by the laboratory shall be demonstrated to the satisfaction of the ER and the IEC. The IEC shall regularly audit the measurement performed by the laboratory to ensure the accuracy of measurement results. The ET Leader shall provide the ER with one copy of the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix A for his reference.

3.5         Monitoring Location

3.5.1        Four representative Air Quality Monitoring stations (AMSs) are proposed as follows:

Table 3.1     Proposed Dust Monitoring Stations

Monitoring Stations

Location

AMS1

Po Toi O Tsuen Road, House No. 28

AMS2

In front of Hung Shing Temple

AMS3

Temporary Structure (House) near Rocky Shore

AMS4

Fairway Vista

3.5.2        The location of the stations can be found in Figure 3-1.

3.5.3        The status and locations of dust sensitive receivers may change after issuing this manual. In this case, the ET Leader shall propose alternative monitoring locations taken into account the following considerations and seek approval from the ER and the IEC:

(a)           locate at the work boundary or such locations close to the major dust emission source;

(b)           locate close to the sensitive receivers; and

(c)           take into account the prevailing meteorological conditions.

3.6         Placement of Equipment

3.6.1        The ET shall agree with the ER in consultation with the IEC on the position of the HVS for the installation of the monitoring equipment. When positioning the samplers, the following points shall be noted:

(a)           a horizontal platform with appropriate support to secure the samplers against gusty wind should be provided;

(b)           no two samplers should be placed less than 2 meters apart;

(c)           the distance between the sampler and an obstacle, such as buildings, must be at least twice the height that the obstacle protrudes above the sampler;

(d)          a minimum of 2 meters of separation from walls, parapets and penthouses is required for rooftop samplers;

(e)           a minimum of 2 meters separation from any supporting structure, measured horizontally is required;

(f)            no furnace or incinerator flue is nearby;

(g)           airflow around the sampler is unrestricted;

(h)           the sampler is more than 20 meters from the dripline;

(i)             any wire fence and gate, to protect the sampler, should not cause any obstruction during monitoring;

(j)             permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and

(k)           a secured supply of electricity is needed to operate the samplers.

3.7         Baseline Monitoring

3.7.1        Baseline monitoring shall be conducted to determine the existing air quality in terms of 1-hour and 24-hour TSP levels before commencement of construction work. A consecutive measurement for 14 days shall be done for 24-hour TSP at all monitoring stations. At least 3 sets of 1-hour TSP data shall also be collected every day during this period, at the predicted time in which greatest impact is expected.

3.7.2        During the baseline monitoring, there should be no major construction or dust generating activities near the monitoring stations. The ET shall propose a monitoring schedule to the IEC so that he can conduct onsite audit to ensure the accuracy of the measurement where necessary.

3.7.3        Alternative baseline AMS that can give representative baseline result may be proposed for ER and IEC’s approval with justifications.

3.7.4        In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET shall liaise with the IEC and ER to agree on an appropriate set of data to be used as a baseline reference and submit to EPD for approval.

3.7.5        The baseline monitoring data shall be reviewed once every three months. When there is seasonal change to ambient conditions, the baseline condition may need to be updated. Repeated measurement shall be conducted during which no dust generating activity is being carried out near the AMS. If a change in ambient condition is recorded, the baseline levels and therefore air quality criteria should be revised accordingly and agreed with the IEC and EPD.

3.8         Impact Monitoring

3.8.1        Impact monitoring shall be carried out throughout the construction period at all AMSs. 24-hour TSP sampling shall be conducted at a frequency of at least once in every 6 days, while that for 1-hour TSP shall be at least 3 times in every 6 days when the highest dust impact takes place. Similar to baseline monitoring, the ET shall submit a monitoring schedule to the IEC for onsite audit of the accuracy of the monitoring result where necessary.


3.8.2        The ET shall clearly define and strictly follow the starting and ending time for 24-hour TSP monitoring for each AMS.

3.8.3        If exceedance of air quality criteria is recorded, more frequent measurement shall be done within the specified timeframe in accordance to the Action Plan. The additional monitoring shall be continued until the excessive dust emission or the deterioration in air quality is rectified, and upon agreement with the IEC.

3.9         Air Quality Performance Limit

3.9.1        The following table shows the action and limit levels for 1-hour and 24-hour TSP levels, while the baseline monitoring results shall be interpreted to derive the action levels.

Table 3.2   Action and Limit Levels for Air Quality

Parameters

Action

Limit

24-hour TSP Level in µg m-3

For baseline level £ 200 µg m-3, Action level = (baseline level * 1.3 + Limit level)/2;

For baseline level > 200 µg m-3 Action level = Limit level

260 µg/m3

1-hour TSP Level in µg m-3

For baseline level £ 384 µg m-3, Action level = (baseline level * 1.3 + Limit level)/2;

For baseline level > 384 µg m-3, Action level = Limit level

500µg/m3

3.10     Event and Action Plan

3.10.1    Should non-compliance of the air quality criteria occur, actions in accordance with the Action Plan in Appendix C shall be carried out.

3.11     Mitigation Measures

3.11.1    The EIA proposed a number of construction phase mitigation measures, examples as follows:

Construction Phase

(a)    Hoarding of not less than 2.4 m high shall be erected from ground level to surround the work area along Po Toi O Chuen Road except for a site entrance or exit.

(b)   Good housekeeping to minimize dust generation, e.g. by properly handling and storing dusty materials.

(c)    Adopt dust control measures, such as dust suppression using water spray on exposed soil, in areas with dusty construction activities and during material handling.

(d)   Minimize exposed earth after completion of work in a certain area by hydroseeding, vegetating, soil compacting or covering with bitumen.

(e)    Provide wheel washing at site exit to prevent carrying dust outside of the site.

(f)    Cover materials on trucks before leaving the site.

(g)   Limit traffic speed of construction trucks within the construction site and in Po Toi O, maximum at 10km/hr.

(h)   As there is limited space in Po Toi O, stockpiling should be avoided. However, if found necessary, the materials should be covered by impervious materials such as tarpaulin.

Operational Phase

(a)    Conduct regular inspection of the tanks to check for leakage of gas.

(b)   Direct odorous gas to odour removal system for treatment prior to exhausting into the atmosphere.

(c)    Maintain the removal efficiency of screenings and grits by flushing the screens and grit sump regularly to prevent build-up of solids.

(d)   Maintain the efficiency of MBR membrane by removing organic and inorganic debris with sodium hypochlorite and oxalic acid .

(e)    Replace worn filters to maintain the odour removal efficiency at 99.5%.

(f)    Remove sludge regularly to prevent build-up of odourous gas.

(g)   Sludge tanker should be parked inside the sewage treatment plant for sludge removal where the air is extracted for deodourization.

(h)   Sludge should be transferred to sludge tanker by coupling method to prevent odour leakage.

(i)     Screenings, grits and worn filters should be stored in sealed containers inside the STP and during removal for disposal.

(j)     Clean all the tanks with water regularly.

3.11.2    Detailed mitigation measures are listed out in the Implementation Schedule of Recommended Mitigation Measures in Appendix A. Implementation status and the effectiveness of these measures shall be audited through regular site inspection.

4                    Noise

4.1         Introduction

4.1.1        In the construction phase, the major noise impact will arise from the use of powered mechanical equipment. With implementation of noise mitigation measures, it is anticipated that the construction noise impact would be reduced to acceptable level. Regular monitoring of noise level should be carried out at noise monitoring stations near representative sensitive receivers before and throughout construction work to ensure that relevant noise standard can be met.

4.1.2        As most of the plant equipment for sewage treatment are stored underground and the STP is enclosed by a concrete structure, operational noise impact is expected to be acceptable. Therefore, no monitoring or audit is proposed.

4.1.3        In this section, the equipment, requirements, monitoring locations, criteria and protocols for the monitoring and audit of noise impacts during the construction of the proposed sewerage works under the Project are presented.

4.2         Monitoring Parameters

4.2.1        Construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq). Leq 30min shall be used as the monitoring parameter for the time period between 0700 and 1900 hours on normal weekdays. For all other time periods, Leq 5min shall be employed for comparison with the Noise Control Ordinance (NCO) criteria.

4.2.2        As supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference. 

4.3         Monitoring Equipment

4.3.1        Sound level meters shall be employed to measure the construction noise level. It should comply with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications in accordance to the Technical Memorandum (TM) issued under the NCO.

4.3.2        An acoustic calibrator shall be used to validate the accuracy of the sound level meter before and after each noise measurement. The calibrator can generate a known sound pressure level at a known frequency. The noise record will only be accepted if the calibration level from before and after the noise measurement agrees to within 1.0 dB.

4.3.3        Sufficient number of the above equipment shall be provided by the ET, who will also be responsible for installation, operation, maintenance and dismantlement. All equipment and instrumentation shall be clearly labelled.

4.4         Monitoring Requirement

4.4.1        Noise measurement shall normally be at a point 1 m from the exterior of the sensitive receiver building façade and be at a position 1.2 m above the ground. If the normal monitoring position cannot be accessed, an alternative position may be chosen, and a correction to the measurements shall be made. For reference, a correction of +3 dB(A) shall be made to the free field measurements. The ET shall agree with the IEC on the monitoring position and the corrections adopted. The agreed position shall be chosen in subsequent baseline and impact monitoring.

4.4.2        Noise measurements should be made in accordance with standard acoustical principles and practices in relation to weather conditions.

4.5         Monitoring Location

4.5.1        There are three kinds of construction work near the sensitive receivers: (1) construction of STP, (2) gravity sewers and rising mains installation and (3) horizontal directional drilling for submarine outfall. As such, four representative Noise Monitoring Stations (NMSs) are proposed near these work sites as follows:

Table 4.1   Proposed Construction Noise Monitoring Locations

Monitoring Stations

Location

NMS1

Po Toi O Tsuen Road, House No. 28

NMS2

In front of Hung Shing Temple

NMS3

Temporary Structure (House) near Rocky Shore

NMS4

Fairway Vista

4.5.2        The location of the stations can be found in Figure 3-1.

4.5.3        The status and locations of noise sensitive receivers may change after issuing this manual. In this case, the ET Leader shall propose alternative monitoring locations taken into account the following considerations and seek approval from the ER and the IEC:

(a)    locate close to the major site activities which are likely to have noise impacts;

(b)   locate close to the most affected existing NSRs; and

(c)    take into account the possibility of minimizing disturbance to occupants at the NSRs during monitoring.


4.6         Baseline Monitoring

4.6.1        Baseline noise measurement shall be conducted to determine the background noise before commencement of work. Daily measurement of A-weighted levels Leq, L10 and L90 shall be conducted for at least two weeks. The sample period shall be 30 minutes between 0700 and 1900.

4.6.2        During the baseline monitoring, there should be no major construction or noise generating activities near the monitoring stations. The ET shall propose a monitoring schedule to the IEC so that he can conduct onsite audit to ensure the accuracy of the measurement where necessary.

4.6.3        Alternative baseline NMS that can give representative baseline result may be proposed for ER and IEC’s approval with justifications.

4.6.4        In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET shall liaise with the IEC and ER to agree on an appropriate set of data to be used as a baseline reference and submit to EPD for approval.

4.7         Impact Monitoring

4.7.1        For daytime construction work on normal weekdays (0700-1900 Monday to Saturday), one set of 30-min measurement shall be carried out at each NMS every week based on the measurement procedures under the Noise Control Ordinance-TM. Similar to baseline monitoring, the ET shall submit a monitoring schedule to the IEC beforehand.

4.7.2        If noise exceedance is being recorded, additional noise monitoring shall be conducted in accordance to the Event Action Plan. The monitoring shall consider complete if the exceedance is being rectified or proved to be from source other than the project construction work.

4.7.3        Sample data sheet can be found in Appendix B.

4.8         Noise Performance Limit

4.8.1        The EIAO-TM sets the statutory limit for noise level produced during construction work.

Table 4.2   Action and Limit Levels for Noise

Time Period

Action Level

Limit Level

0700-1900 hrs on normal weekdays

When one documented complaint is received

75dB(A)

4.9         Event and Action Plan

4.9.1        Should non-compliance of the noise criteria occur, actions in accordance with the Action Plan in Appendix C shall be carried out.


4.10     Mitigation Measures

4.10.1    The EIA proposed a number of construction phase mitigation measures, examples as follows:

(a)    Adopt good site practice, such as regular maintenance of plant equipment, throttle down unused machines.

(b)   Use Quality Powered Mechanical Equipment (QPME).

(c)    Erect 3m high mobile barriers in the direction of noise sensitive receivers within a few meters of stationary plants and within about 5m of more mobile plant such as hydraulic breaker to prevent direct view. The barrier should have skid footing and a small cantilevered upper portion. The minimum surface density of the movable noise barrier is 7 kg/m2 and provide with noise absorbing material.

(d)   Operate air compressor, generator and concrete pump within enclosure.

(e)    Cover the noisy part of piling machine with acoustic mat.

(f)    Orient noisy plant equipment so that noise emitted will not be directed towards the NSRs.

(g)   Strategic location and scheduling of the construction work front to minimize cumulative effect (e.g. the work front of village sewer installation near NSRs PTO_N1 and PTO_N3 shall not be conducted concurrently with installation of Po Toi O Chuen Road sewer and horizontal directional drilling respectively).

(h)   Vibratory poker shall only be operated 4m away from NSR and with noise barrier properly erected. Surfacing work within 4m from NSR shall be carried out by manual method.

(i)     Hand-held breaker shall be fitted with mufflers. A movable enclosure made up of plywood is proposed to surround both worker and breaker during breaking process.

(j)     Should there be concurrent project in the vicinity, continuous discussion between contractors shall be conducted to plan the location and programme of construction work to minimize cumulative impact.

4.10.2    Detailed mitigation measures are listed out in the Implementation Schedule of Recommended Mitigation Measures in Appendix A. Implementation status and the effectiveness of these measures shall be audited through regular site inspection.

 


5                    Water quality

5.1         Introduction

5.1.1        Potential water quality impact arising from the construction activities (for examples, site runoff of exposed soil, earthworks and stockpiles during rainstorms and sewage generated from construction workforce) would be minimized by implementing appropriate mitigation measures and good site management practices.

5.1.2        Dredging and backfilling works associated with the diffuser of the submarine outfall at outer Poi Toi O Bay shall be confined within fully enclosed cofferdam. Dredger barge will be anchored outside the cofferdam and no opening of cofferdam is required during dredging and filling works. No release of suspended solids is expected. Minor displacement of bottom sediment may arise during installation of cofferdam.

5.1.3        Construction phase monitoring is proposed to keep track of the variation in water quality to identify any unacceptable impact at the sensitive receivers during installation and extraction of cofferdam and dredging works. Site audit shall be conducted regularly to ensure that the mitigation measures recommended in the EIA Report and this EM&A Manual are fully implemented.

5.1.4        Treated effluent will be discharged at outer Po Toi O Bay during the normal operation of the STP. The effluent quality shall be regularly monitored in accordance with the requirements under Discharge License. No substantial change in water quality in the Po Toi O Bay is expected. However, in view of the sensitivity of fish culture zone, corals and amphioxus to water quality change, marine water quality monitoring is proposed for the first commencement year to ensure that no unacceptable deterioration of water quality arises in the enclosed bay.

5.1.5        Practical and well sufficient mitigation measures have been proposed to protect water quality during marine construction works, such as no open dredging for submarine outfall by adopting HDD, dredging and filling within fully enclosed cofferdam and use of closed grab for dredging. During operation of the proposed STP, effluent that meets the water quality requirements under WPCO will be discharged. As no adverse water deterioration is expected during construction and operational phases, real-time reporting of monitoring data for the Project through a dedicated internet website is considered not necessary.

5.2         Construction Phase EM&A

Monitoring Requirement

5.2.1        Major water quality impact will be originated from minor displacement of suspended solids during installation and extraction of cofferdam around the proposed diffuser. Regular monitoring of water quality should be carried out at water quality monitoring stations (WMS) near the cofferdam (impact station), upstream of the impact (control stations), and near representative water sensitive receivers (WSRs) (e.g. Fish Culture Zone, coral and Amphioxus) before and throughout installation and extraction works. Although no sediment is expected to be released during dredging, water quality monitoring during dredging works will also be proposed.

Monitoring Parameters

5.2.2        Suspended solids (SS) and in-situ water quality data (temperature, pH, turbidity, water depth, salinity, dissolved oxygen and percentage of saturation) shall be collected.

5.2.3        Other relevant data should also be recorded, including monitoring location/position, time, tidal stages, weather conditions and any special observation or works that may affect the monitoring results in the vicinity.

5.2.4        To ensure sufficient data for robust analysis, duplicate in-situ data shall be collected. In case the difference in the duplicate in-situ measurement results is larger than 25%, the third set of in-situ measurement shall be carried out for result confirmation purpose.

5.2.5        A sample data sheet can be found in Appendix B.

Monitoring Location

5.2.6        Six water monitoring stations are proposed at Po Toi O Fish Culture Zone (FCZ), major amphioxus habitat and rocky shores near the dredging point where coral thrives. Based on the prediction of Delft-3D model, water current flows from the open sea through Clear Water Bay towards Po Toi O bay during flood tide while the reverse happens during ebb tide. Therefore, three control stations will be allocated at where fresh marine water is not affected by the cofferdam installation/extraction works and two impact stations will be set near the cofferdam under different tidal periods. The location of the stations can be found in Figure 5-1.

Table 5.1   Marine Water Monitoring Locations in Construction Phase

Station

Monitoring Period

Description

Easting

Northing

WMS1

Mid-Ebb,

Mid-Flood

Po Toi O Fish Culture Zone

848387

815201

WMS2

Po Toi O Fish Culture Zone

848479

815378

WMS3

Rocky Shore with Corals

848644

815391

WMS4

Rocky Shore with Corals

848774

815602

WMS5

Rocky Shore with Corals

848578

815591

WMS6

Major Amphioxus Habitat

848639

815523

I1

Mid-Flood

Impact Monitoring Station

848643

815692

I2

Mid-Ebb

Impact Monitoring Station

848722

815810

C1

Mid-Flood

Control Station

848904

816052

C2

Mid-Ebb

Control Station

848529

815373

C3

Mid-Ebb

Control Station

848243

815710

5.2.7        Water samples shall be extracted at 1m below surface, 1m above seabed and the mid-depth level at where the water depth is at least 6m. However, if the water depth is less than 3m, water samples shall only be collected at the mid-depth level. For stations with depth less than 6m, the mid-depth sample can be omitted.

Monitoring Frequency

5.2.8        Baseline monitoring shall be carried out 3 days per week, at mid-flood and mid-ebb tides (within ± 1.75 hour of the predicted time), for a period of 4 weeks prior to the commencement of the marine works. The interval between two sets of monitoring shall not be less than 36 hours. The monitoring period should avoid concurrent marine project in the vicinity.

5.2.9        Impact monitoring shall also be conducted at the same frequency throughout the whole cofferdam installation/extraction work and during dredging works. In case exceedance of Action/Limit Level is recorded, the frequency shall be increased as per the Event and Action Plan.

Construction Phase Site Inspection

5.2.10    Weekly site audit is recommended to monitor the implementation of the proposed water quality mitigation measures and check the Contractor’s work practice on water pollution prevention during construction phase.

5.2.11    Should water pollution is observed (e.g. discharge of silty water into storm drains), the ET should record the environmental deficiency for investigation. The Contractor should be notified and responsible for carrying out rectification work immediately. The ET shall re-inspect the Project Site described in Section 2.3.1 and review the effectiveness of the remedial measure performed until satisfaction. The Contractor shall implement preventive measure to avoid causing the same problem.

5.3         Operational Phase EM&A (Effluent Quality)

5.3.1        The water quality of the effluent should meet the requirements under Technical Memorandum on Effluent Discharge Standard before discharge. Therefore, effluent testing should be carried out at the discharge outlet at interval stipulated in the discharge license issued by the EPD. The water quality parameters shall be referred to the discharge license as well. Should exceedance be recorded, the plant operator should be notified, who shall identify the cause of non-compliance and formulate remedial measures. The monitoring frequency should increase until the effluent quality can meet the criteria. No effluent should be discharged until the effluent quality meets the required standard.

5.4         Operational Phase EM&A (Marine Water Quality)

Monitoring Requirement

5.4.1        Effluent will be discharged at the diffuser. Regular monitoring of marine water quality should be carried out at WMS to check whether the Water Quality Objectives (WQO) can be fulfilled. The monitoring should commence prior to operation of the STP to establish the baseline water quality condition.

Monitoring Parameters

5.4.2        Water quality parameters under the WQO that may be affected by effluent discharge shall be monitored at the nearby sensitive receivers: E. coli, DO, salinity, SS, ammonia (NH3-N) and total inorganic nitrogen (TIN). As in the construction phase, other in-situ water quality data shall also be collected (temperature, pH, turbidity, water depth and percentage of saturation for DO).

5.4.3        Other relevant data should also be recorded, including monitoring location/position, time, tidal stages, weather conditions and any special observation or works that may affect the monitoring results in the vicinity.

5.4.4        To ensure sufficient data for robust analysis, duplicate in-situ data shall be collected. In case the difference in the duplicate in-situ measurement results is larger than 25%, the third set of in-situ measurement shall be carried out for result confirmation purpose.

5.4.5        A sample data sheet can be found in Appendix B.

Monitoring Location

5.4.6        The water monitoring stations shall follow those in the construction phase (WMS1-WMS6).

5.4.7        Water samples shall be extracted at 1m below surface, 1m above seabed and at the mid-depth level at where the water depth is at least 6m. However, if the water depth is less than 3m, water samples shall only be collected at the mid-depth level. For stations with depth less than 6m, the mid-depth sample can be omitted.

Monitoring Frequency

5.4.8        Baseline Monitoring shall be carried out for two times per month for a period of  6 months prior to the commencement of the operation of the PTOSTW. The 6-month period shall cover both wet and dry seasons. Water samples shall be collected during mid-ebb and mid-flood tides (within ± 1.75 hour of the predicted time) on each monitoring day. The monitoring period should avoid concurrent marine project in the vicinity.

5.4.9        Operational phase monitoring shall also be conducted at the same frequency as in baseline for the first three months of operation of PTOSTW (i.e. twice per month). If the results are satisfactory, the frequency will be reduced to once per month. However, if exceedance is subsequently recorded, the frequency shall return to twice per month until satisfactory results are obtained again for three consecutive months. The whole monitoring shall last for one year. If no exceedance is recorded due to operation of the PTOSTW, no further monitoring is required.

Table 5.2   Overall Summary of Monitoring Requirements in Construction and Operational Phases

Monitoring Stations

Parameters

Duration

Frequency

Construction Phase

WMS1-WMS6, I1, I2, C1-C3

·      Temperature(°C)

·      pH(pH unit)

·      Turbidity (NTU)

·      Water depth (m)

·      Salinity (ppt)

·      DO (mg/L and % of saturation)

·      SS (mg/L)

Baseline: 4 weeks

·      3 days per week

Construction:
Throughout installation and extraction of cofferdam and during dredging

Operational Phase

WMS1-WMS6

·      Temperature(°C)

·      pH(pH unit)

·      Turbidity (NTU)

·      Water depth (m)

·      Salinity (ppt)

·      DO (mg/L and % of saturation)

·      SS (mg/L)

·      NH-N (mg/L)

·      TIN (mg/L)

·      E. coli (no./100ml)

Baseline: 6 months before operation, covering wet and dry seasons

·      2 days per month

Operation: at least one year from operation

·      First 3 months:
2 days per month

·      Subsequent months:
1 day per month

·      If exceedance is recorded, frequency increases back to 2 days per month until no further deterioration is recorded for 3 months

·      Completed in one year

Notes:
1. Water Sampling Depth for all monitoring:

·         water depths: 1m below sea surface, mid-depth and 1m above sea bed

·         If the water depth is less than 3m, mid-depth sampling only

·         If water depth less than 6m, mid-depth may be omitted.

2. Sampling time for all monitoring: Mid-Ebb, Mid-Flood

5.5         Monitoring Equipment

Position System

5.4.1        A hand held Global Positioning System (GPS) shall be used during water quality monitoring to ensure the monitoring vessel is at the correct location before taking measurements. GPS shall be calibrated at checkpoint (e.g. Quarry Bay Survey Nail at Easting 840683.49 and Northing 816709.55) to ensure the monitoring station is at the correct position before taking measurement and water samples.

Water Depth Detector

5.4.2        A portable, battery-operated echo sounder shall be used for the determination of water depth at each designated monitoring station.

Salinity

5.4.3        A portable salinometer capable of recording salinity within the range of 0-40 ppt shall be used for salinity measurements.

Dissolved Oxygen (DO) and Temperature Measuring Equipment

5.4.4        The instrument for measuring dissolved oxygen and temperature shall be portable and weatherproof complete with cable, sensor, comprehensive operation manuals and use DC power source. It shall 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.

5.4.5        It shall have a membrane electrode with automatic temperature compensation complete with a cable.

5.4.6        Sufficient stocks of spare electrodes and cables shall be available for replacement where necessary.

5.4.7        The instrument for measuring DO shall obtain built-in salinity compensation.

Turbidity Measurement Equipment

5.4.8        Nephelometric method shall be used in measuring in-situ turbidity. The instrument shall be portable, weatherproof complete with a cable, sensor, comprehensive operation manuals and DC power source. It shall have a photoelectric sensor capable of measuring turbidity between 0-1000 NTU and complete with a cable with at least 25 m in length. The meter shall be calibrated in order to establish the relationship between NTU units and suspended solids level. Turbidity shall be measured on split water sample collected from the same depths of suspended solid samples.

pH

5.4.9        The instrument shall consist of a potentiometer, a glass electrode, a reference electrode and a temperature-compensating device. It shall be readable to 0.1pH in a range of 0 to 14. Standard buffer solutions of at least pH 7 and pH 10 shall be used for calibration of the instrument before and after use.

Sampler

5.4.10    A water sampler, consisting of a transparent PVC or glass cylinder of a capacity of not less than two litres which can be effectively sealed with cups at both ends shall be used. The water sampler shall 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.

Sample Container and Storage

5.4.11    Following collection, water samples for laboratory analysis shall be stored in high density polythene bottles with appropriate preservatives added, packed in ice (cooled to 4°C without being frozen), delivered to the laboratory and analysed as soon as possible. Sufficient volume of samples shall be collected to achieve the detection limit.

5.4.12    Water samples for E. coli shall be collected in sterile bottles with leak-proof lids.

5.4.13    Water samples for suspended solids determinations shall be stored in high density polythene bottles with no preservative added.

Calibration of In-situ Instruments

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

5.4.15    For the on-site calibration of field equipment (Multi-parameter Water Quality System), the BS 1427:2009, "Guide to on-site test methods for the analysis of waters" shall be observed.

5.4.16    Sufficient stocks of spare parts shall 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.

Laboratory Measurement or Analysis

5.4.17    The testing of all parameters shall be conducted by a HOKLAS accredited laboratory or operator of the