Environmental Protection Department

 

Agreement No. CE20/2004 (EP)

North East New Territories (NENT) Landfill Extension

 

Environmental Monitoring & Audit Manual

 

May 2007

 

 

 

 

 

 

 

 

 

 

 


Contents

 

 

 

                                                                                                                                                                                                   

1          Introduction  2

1.1          Background  2

1.2          Purpose and Scope of this Manual 2

1.3          Description of the Project 2

1.4          Project Programme  2

2          Scope of EM&A Programme  2

2.1          Objectives of EM&A Programme  2

2.2          Organisation for EM&A Programme  2

2.3          Environmental Management Plan  2

2.4          Waste Management Plan  2

2.5          Baseline Monitoring  2

2.6          Impact Monitoring  2

2.7          Compliance with Action and Limit Levels  2

2.8          Event and Action Plan  2

2.9          Environmental Audit 2

2.10        Reporting  2

2.11        Cessation of EM&A Programme  2

3          Air Quality Monitoring  2

3.1          Construction Dust 2

3.2          Odour 2

3.3          Precautionary Measures During Operational, Restoration and Aftercare Phases  2

4          Noise Monitoring  2

4.1          Monitoring Parameters  2

4.2          Monitoring Equipment 2

4.3          Monitoring Location  2

4.4          Baseline Monitoring  2

4.5          Construction Noise  2

4.6          Operational Noise  2

4.7          Traffic Noise  2

4.8          Event and Action Plan  2

4.9          Environmental Mitigation Measures  2

5          Water Quality Monitoring  2

5.1          Introduction  2

5.2          Precautionary / Mitigation Measures during Construction and Operation Phases  2

5.3          Leachate Monitoring  2

5.4          Groundwater Monitoring  2

5.5          Surface Water Monitoring  2

5.6          Event and Action Plan  2

6          Waste Management 2

6.1          Introduction  2

6.2          Waste Control and Mitigation Measures  2

7          Landfill Gas Monitoring  2

7.1          Background  2

7.2          General Requirements  2

7.3          Monitoring Parameters  2

7.4          Monitoring Equipment 2

7.5          Monitoring Locations  2

7.6          Monitoring Frequency  2

7.7          Monitoring Procedures  2

7.8          A/L Levels and EAP  2

7.9          Mitigation Measures  2

8          Landscape and Visual Monitoring  2

8.1          Introduction  2

8.2          Monitoring Details  2

9          Cultural Heritage Monitoring  2

9.1          Introduction  2

9.2          Monitoring Requirements  2

9.3          Ngong Tong (North and West of Shek Tsai Ha Road: Western & Central Section) 2

9.4          Tong To Shan (North of Shek Tsai Ha Road: east section) 2

9.5          AMO requirements for Survey and Preservation  2

10         Ecological Monitoring  2

10.1        Introduction  2

10.2        Ecological Mitigation Measures  2

10.3        Monitoring and Audit for Ecology  2

11         Environmental Audit 2

11.1        Site Inspection  2

11.2        Compliance with Environmental Requirements  2

11.3        Environmental Complaints  2

12         Reporting  2

12.1        General 2

12.2        Baseline Monitoring Report 2

12.3        Impact EM&A Reports  2

12.4        Data Keeping  2

12.5        Interim Notification of Environmental Exceedances  2

 

 

 

 

APPENDICES

 

Appendix A         Tentative Outline Programme

Appendix B         Project Organisation

Appendix C         Environmental Mitigation Implementation Schedule

Appendix D         A Sample List of VOC Monitoring Parameters

 

 

DRAWINGS

 

24315/01/001        Location Plan

24315/01/107        Landfill Extension Layout Option 4

24315/13/151        Air Monitoring Location

24315/13/251        Noise Monitoring Location

24315/13/504        Existing Landfill and Landfill Extension Monitoring Plan

24315/13/606        Archaeological Findings

24315/13/702        Habitat Map Location of Species of Conservation interest overlaid with Option 4

 

 

 

 


1                  Introduction

Currently, around 6 million tonnes of waste are disposed each year at the three strategic landfills in Hong Kong, including the West New Territories (WENT) Landfill, the South East New Territories (SENT) Landfill, and the North East New Territories (NENT) Landfill.

At time of commissioning, the three landfills with a total capacity in the order of 140 Mm³ were expected to be able to meet the waste disposal needs of Hong Kong until 2020 or beyond.  The actual waste disposal rate at the landfills has been, however, higher than expected.  It is thus projected that the three existing landfills would last only until early-to-mid next decade.

To tackle the problem, further efforts have been taken to reduce and recycle waste.  Also, the HKSAR Government has planned to develop Integrated Waste Management Facilities (IWMF) to substantially reduce the volume of waste requiring landfill disposal.  Yet these measures could not obviate totally the need for new landfill capacity in Hong Kong, especially as the implementation of IWMF will take time and as its residues will still need to be disposed.

The Environmental Protection Department (EPD) of the HKSAR Government therefore commissioned a study in Year 2000 on the Extension of Existing Landfills and Identification of Potential New Waste Disposal Sites.  Amongst the potential sites recommended in this territory-wide study is the extension of the existing NENT Landfill, with a target capacity of about 19 Mm³.  As shown in the attached Drawing No. 24315/01/001, the proposed extension, of about 70 ha, is located immediately east of the existing NENT Landfill.  A large proportion of the Extension area is in fact the Stockpile and Borrow Area of the existing landfill.  

In February 2005, EPD appointed Ove Arup & Partners Hong Kong Ltd. To undertake a detailed feasibility study for the NENT Landfill Extension (hereafter referred to “the Project”), with the following key tasks: formulation and evaluation of layout options for the landfill extension; EIA study; and conceptual design of landfill facilities.

Environmental Monitoring and Audit (EM&A) is an important aspect in the EIA process which specifies the timeframe and responsibilities for the implementation of environmental mitigation measures.  The requirements on environmental monitoring (including baseline and impact monitoring) are given in the EM&A Manual (the Manual) which is a supplementary document to the EIA Study for the Project and prepared in accordance with the requirements in the EIA Study Brief and Technical Memorandum on Environmental Impact Assessment Process (TM-EIAO). 

The purpose of this EM&A Manual is to guide the establishment of an EM&A programme to ensure compliance with the EIA recommendations, to assess the effectiveness of recommended mitigation measures, and to identify further need for additional mitigation measures or remedial action. 

This Manual outlines the monitoring and audit requirements for the construction, operation, restoration and aftercare stages of the NENT Landfill Extension.  It aims to provide systematic procedures for monitoring, auditing and minimising environmental impacts associated with construction works and operational activities.

Hong Kong environmental regulations and the Hong Kong Planning Standards and Guidelines have served as environmental standards and guidelines in the preparation of this Manual.  This EM&A Manual was prepared in accordance with the requirements as stipulated in Annex 21 of the TM-EIAO. 

This Manual contains the following information:

·         Organisation, hierarchy and responsibilities of the DBO Contractor, Environmental Team (ET), Independent Environmental Checker (IEC), and Independent Consultant (IC), with respect to the EM&A requirements during the construction, operation, restoration and aftercare phases of landfill extension;

·         Information on project organisation and programming of construction activities;

·         Requirements with respect to the construction schedule and necessary EM&A programme to track the varying environmental impacts;

·         Full details of methodologies to be adopted, including all field, laboratory and analytical procedures, and details on quality assurance;

·         Procedure for undertaking on-site environmental audits;

·         Definition of Action and Limit Levels;

·         Establishment of Event and Action Plans;

·         Requirements of reviewing pollution sources and working procedures required in the event of non-compliance of environmental criteria and complaints;

·         Requirements for reviewing the EIA predictions, implementation of mitigation measures, and effectiveness of environmental protection and pollution control measures adopted; and

·         Presentation of requirements for EM&A data and appropriate reporting procedures.

1.3.1            General Description of the Project

The development of the NENT Landfill Extension will involve the following works:

·         Site formation, drainage diversion and preparation;

·         Installation of liner system;

·         Installation of leachate collection, treatment and disposal facilities;

·         Installation of gas collection, utilization and management facilities;

·         Operation and environmental monitoring of landfill;

·         Restoration and aftercare.

1.3.2            Key Project Requirements

The key project requirements for the NENT Landfill Extension are:

·         Development of sanitary landfill that covers an area of about 70ha with an estimated void space of 21Mm3;

·         Provision of liner system for the landfill to prevent contamination of land and water resources;

·         Provision of leachate collection, treatment and disposal facilities with sufficient capacity for handling the leachate arising from the new landfill;

·         Provision of landfill gas (LFG) collection, utilisation and management facilities;

·         Provision of utilities, drainage and road network necessary for the proper operation of the Project;

·         Provision of facilities (both civil works and electrical and mechanical equipment) for waste reception, inspection, charging, handling and compaction, and plant maintenance;

·         Provision of facilities for site administration;

·         Operation of landfill in compliance with all relevant engineering, geotechnical and environmental standards;

·         Restoration of landfill in compliance with all relevant engineering, geotechnical and environmental standards;

·         Provision of aftercare for the landfill for a period of about 30 years

·         Carrying out environmental monitoring and audits throughout construction, operation, restoration and aftercare of the landfill; and

·         Implementation of environmental measures necessary for the protection of the surrounding environment.

1.3.3            Size, Scale, Shape and Design of the Project

The landfill extension site will be a bowl-shape area with a large void space in the middle for waste filling. The northwestern and southeastern boundaries of the landfill extension site follow the ridgelines to maximise the landfill capacity.  Some set back of the northern boundary is included to minimise the impact to woodland and Lin Ma Hang Catchment. The total site area is 70ha and the final height of the landfill would be +255mPD (Drawing No 24315/01/001 & 107).  Various activities during construction, operation, restoration and aftercare of landfill are discussed in the following sub-sections.  The key design features are summarised below: 

·         Bottom liner system – separate rubbish and leachate from groundwater;

·         Landfill cells – store waste within the unit;

·         Storm water drainage system – collect rain water run off on the landfill;

·         Leachate collection system – collect liquid leaching from the waste mass and convey it to a leachate treatment plant prior to discharging to Shek Wu Hui Sewage Treatment Works;

·         Gas collection system – collect gases formed during the decompositon of waste. These gases will be treated and utilised for production of electricity on site; and

·         Covering and capping – seal off the top of the landfill with a gas venting layer, an impermeable mineral layer, a drainage layer of at least 0.5m and at least 1m of top soil.

1.3.4            Construction Phase Activities 

Simple excavation and slope formation works will be carried out during the construction stage.  The permanent works comprise cut and fill earthworks, slope formation and earth wall construction.  The temporary works will involve the formations of temporary ditches along the sides of excavations and associated drainage works, and material storage areas.  During site formation, sediment will be contained in permanent detention ponds/silt traps that will be constructed according to landfill phasing. Final design and location of sediment traps are yet to be decided, but are likely to be down gradient of each landfill phase or in the downstream valleys near the existing waste reception area.  Where possible they will be maintained during the operation of each phase to ensure the effective control of operational soil erosion problem.

1.3.5            Operation Phase Activities 

During operation, waste will be disposed of at individual landfill cells.  Deposited waste will be compacted to thin layers of up to two metres in thickness.  The works will be maintained at a gradient of not greater than 1 in 3 to ensure the effectiveness of the compaction equipment.  Daily cover (about 150mm if soil cover used) will be applied to control environmental nuisances such as windblown litter, odour, vermin, flies and birds.  There are other more effective alternative biodegradable materials for use as daily cover, including:

·         Heavy duty reusable and biodegradable sheets;

·         Biodegradable, non-reusable plastic films;

·         Geotextiles; and

·         Foams and sprays.

Advantages of using alternative daily cover over traditional methods may include preservation of void space and soil material; biodegradable and less permeable to water and gas (reduce water infiltration, odour and dust emission).

1.3.6            Restoration Phase Activities

Restoration is a process to restore a landfill site to a condition suitable for afteruse.  After completion of waste filling, final capping will be applied to minimise infiltration of rainwater into the waste body thus reducing the amount of leachate generated.  The capping system normally includes a number of components including topsoil, subsoil, drainage layer and barrier layer. 

1.3.7            Aftercare Phase Activities

Aftercare is the work done after the replacement of the soil and includes cultivations, fertilisation, planting, construction of pathways, access points, vegetation maintenance and an ongoing long term commitment to the restored landfill.  Landscaped berms will be created and tree planting will be provided during the aftercare period for aesthetic purpose.

The Landfill Extension will start receiving waste only when the Existing NENT Landfill has ceased operation.  The timing of this has yet to be determined as it depends on the rate of waste deliveries in the forthcoming period.  Based on current predictions, the capacity of the Existing Landfill will probably run out by early-to-mid next decade, by which time the Landfill Extension shall start operation. 

Taking into account of the time needed for mobilization and preparatory works prior to commencement of receipt of waste, it may be necessary to award the Landfill Extension contract towards the end of this decade, this should talling with Project Programme anywhere else in the EIA.  In order to ensure that new landfill space will be available before the capacity of the existing landfill runs out. 

It is anticipated that the DBO (Design-Build-Operate) contract form, which has hitherto worked well for the existing waste management contracts (notably the three strategic landfill contracts and the refuse transfer station contracts), will be adopted for NENT Landfill Extension.  Detailed design and formulation of technical details for the construction, operation, restoration and aftercare of the NENT Landfill Extension will be carried out by the DBO Contractor, in accordance with requirements stipulated in the Specification and other documents of the DBO Contract.

A tentative outline programme for implementation of the NENT Landfill Extension is shown in Appendix A.  As pointed out above, the exact timing of the various activities may vary, depending on actual volume of waste to be delivered in the forthcoming years.


2                  Scope of EM&A Programme

The requirements of EM&A programme should include the recommendations from the EIA study and with reference to EPD’s “Environmental Monitoring and Audit Guidelines for Development Projects in Hong Kong”.  Detailed requirements of the EM&A programme for construction, operation, restoration and aftercare phases of this Project are described in the following sections of this EM&A Manual. 

The EM&A requirements recommended in the EIA Report will ensure compliance with the specified mitigation measures.  An EM&A programme should be designed based on these requirements to achieve the following key objectives: 

·         Establishment of existing environmental setting of the site to assist the development of landfill design and to establish a baseline against which any adverse environmental impacts can be evaluated;

·         Provision of a database against which any short- or long-term environmental impacts of the Project can be determined against the Project compliance with regulatory requirements, standards and Government policies;

·         Verification of environmental impacts predicted in the EIA study and provision of an early indication of any failure of environmental control measures or practices to achieve the acceptable standards;

·         Evaluation of environmental impacts during site preparation works and operational phases of the landfill extension project to assist the determination of effectiveness of the mitigation measures to be implemented, ensure compliance with the relevant environmental regulations, and design of any additional mitigation measures requirements;

·         Provision of information to enable environmental audit of Project activities during construction, operation, restoration and aftercare phases, and taking remedial action if unexpected problems or unacceptable impacts arise; and

·         Provision of a basis for long-term monitoring programme folllowing the completion of works during the aftercare phase.  

The proposed project organisation and lines of responsibilities with respect to the EM&A programme are shown in Appendix B, which consists of the Project Proponent (EPD/WFG), DBO Contractor, Environmental Team (ET), Independent Environmental Checker (IEC), and Independent Consultant (IC), etc.  It should be established to take the responsibilities for environmental protection for this landfill extension project.  The IEC will be appointed by the Project Proponent as part of the IC to conduct independent auditing of the overall EM&A programme including environmental and operation monitoring, implementation of mitigation measures, EM&A submissions, and any other submissions required under the Environmental Permit (EP).  The individual responsibilities are:

DBO Contractor

·         Employment of an ET to carry out environmental monitoring, laboratory analysis and reporting of environmental monitoring and audit;

·         Provision of assistance to ET in carrying out monitoring and auditing;

·         Submission of proposals of mitigation measures in case of exceedances of Action and Limit (A/L) Levels in accordance with the Event and Action Plan (EAP);

·         Implementation of mitigation measures to reduce the impacts where A/L Levels are exceeded; and

·         Adherence to the agreed procedures for carrying out complaint investigation.

ET

·         Setting up of all the required environmental monitoring stations;

·         Monitoring of various environmental parameters as required;

·         Analysis of monitoring and audit data and review the success of EM&A programme to cost-effectively confirm the adequacy of mitigation measures implemented and the validity of the EIA predictions and to identify any adverse environmental impacts arising;

·         Carrying out site inspections to investigate and audit the DBO Contractor’s site practices, equipment and work methodologies with respect to pollution control and environmental mitigation, and take proactive actions to pre-empt problems;

·         Auditing and preparation of audit reports on environmental monitoring data and site conditions;

·         Reporting of environmental monitoring and audit results to the IEC, DBO Contractor, IC and Project Proponent or its delegated representative;

·         Recommendation of suitable mitigation measures to the DBO Contractor in case exceedance of A/L Levels in accordance with the EAP; and

·         Undertaking of regular on-site audits/ inspections and reporting to the DBO Contractor and IC of any potential non-compliance; and

·         Following up and closing out of non-compliance actions.

IEC

·         Review of EM&A programme by the ET (at not less than monthly intervals);

·         Auditing of monitoring activities and results (at not less than monthly intervals);

·         Reporting of audit results to the IC and Project Proponent in parallel;

·         Reviewing of EM&A reports (monthly, quarterly and annual summary reports) submitted by the ET;

·         Reviewing of proposal of mitigation measures submitted by the DBO Contractor in accordance with the EAP;

·         Checking of mitigation measures recommended in the EIA Report and EM&A Manual, and ensuring they are properly implemented in timely manner when required; and

·         Reporting of findings of site inspections and other environmental performance reviews to IC and Project Proponent. 

IC

·         Verification and checking DBO Contractor’s activities and ensure that the requirements in the EM&A Manual are fully complied with;

·         Informing DBO Contractor when action is required to reduce impacts in accordance with the EAP;

·         Ensure compliance with the agreed Event Action Plan in case any exceedance.

Sufficient and suitably qualified professional and technical staff should be employed by the respective parties to ensure full compliance with their duties and responsibilities, as required under the EM&A programme for the duration of the Project. 

A systematic Environmental Management Plan (EMP) should be developed and implemented by the DBO Contractor in accordance with the ETWB TC(W) 19/2005 Environmental Management on Construction Sites to ensure effective implementation of the mitigation measures, monitoring and remedial requirements presented in the EIA, EM&A and environmental mitigation implementation schedule (EMIS) (Appendix C).  The IEC should audit the implementation status of EMP and advise the necessary remedial action as required.  Such remedial actions should be enforced through contractual requirements.  The EMP should be certified by the ET and verified by the IEC. 

The EMP should require the DBO Contractor (and sub-contractors) and ET to define in details how to implement the recommended mitigation measures in order to achieve the environmental performance stipulated in the Hong Kong environmental legislation and EIA documents.  The review of on-site environmental performance should be undertaken by IEC through a systematic checklist and audit once the construction commences.  The environmental performance review programme comprises a regular assessment on the effectiveness of the EMP. 

The EMP should summarise the requirements for the DBO Contractor to submit a Landfill Monitoring Plan (LMP) and an Emergency Response Plan (ERP) for approval.  The LMP should describe the procedures and provide details of the environmental monitoring programme for the DBO Contractor to carry out throughout the construction, operation, restoration and aftercare phases of the Project.  The ERP should address various scenarios within NENT Landfill Extension, in particular in the event of leakage of LFG/ leachate, failure of LFG/ leachate treatment operation, fire, chemical/ DG spillage, etc. 

If the DBO Contractor would adopt alternative construction methods or implementation schedules, the detailed modifications of methodology and equipment should be submitted to the IEC for approval prior to the commencement of works.  Any changes in construction methods should be indicated in the revised EMP.  The DBO Contractor should review the EMIS with respect to the design developments and construction methodology.  All necessary mitigation measures identified and recommended in the EIA study are summarised in the EMIS, which specifies the extent, locations, time frame and responsibilities for the implementation of the environmental mitigation measures identified.

The DBO Contractor should develop the waste management requirements as part of the EMP in Section 2.3 above for the construction phase of the Project.  The DBO Contractor should also prepare a Waste Management Plan (WMP) for the Project during the operational, restoration and aftercare phases.  Where waste generation is unavoidable, any opportunities for recycling or reuse of the wastes should be maximised.  If the wastes cannot be recycled, recommendations for appropriate disposal routes should be provided in the WMP.  A method statement for stockpiling and transportation of the excavated materials and other construction wastes should also be included in the WMP and approved before the commencement of construction.  All mitigation measures arising from the approved WMP should be fully implemented.  The WMP should be certified by the ET and verified by IEC. 

It is not anticipated that any significant quantities of excavated C&D materials would require off-site disposal, as most will be reused on-site.  Notwithstanding this, a trip-ticket system should be put in place in accordance with ETWB TC(W) No 31/2004.  Copies/ counterfoils from trip-tickets (showing the quantities of C&D Materials taken off-site) should be kept for record purposes. 

For the purpose of enhancing the management of Construction and Demolition (C&D) materials including rock, and minimising its generation at source, construction would be undertaken in accordance with the Environment, Transport and Works Bureau Technical Circular (Works) No 33/2002 – Management of Construction and Demolition Material Including Rock, or its latest versions. The management measures stipulated in the Technical Circular should be incorporated.

Prior to the commencement of construction works, the baseline conditions of environmental parameters should be established at designated monitoring locations to determine the nature and ranges of natural variation and to demonstrate the suitability of the proposed impact, control and reference monitoring locations in the EM&A programme.  The baseline conditions of the following environmental parameters should be established by the ET, including air quality (dust, organic emissions, odour), noise, water quality (groundwater and surface water), ecology (vegetation and biodiversity), landscape and visual, and cultural heritage. 

During the implementation of the Project, environmental monitoring should be conducted at designated monitoring locations to detect the changes of environmental parameters attributed to the Project.  Impact monitoring should be conducted during all phases of the Project.  The environmental monitoring parameters during construction phase should include air quality (dust, organic emissions, odour), noise, water quality (groundwater and  surface water), ecology (vegetation and biodiversity), landscape and visual, and cultural heritage.  The monitoring during operational, restoration and aftercare phases should include all parameters of construction phase, in addition to leachate and LFG. 

The A/L Levels should be defined for environmental monitoring at designated monitoring locations exceeding which a prescribed response should be required.  Individual A/L Levels should be quantitatively defined for the respective environmental monitoring parameters according to the following basic principles:

2.7.1            Action Level

Action Levels indicate deteriorating ambient environmental quality potentially due to the Project implementation.  It acts as a sign to trigger appropriate remedial actions in order to rectify any mal-practices or non-conformance of Project activities thereby preventing the deterioration of environmental quality and to resume the ambient environmental quality back to normal levels. 

2.7.2            Limit Level

Limit Levels are the statutory and/or contractual levels below which environmental conditions are considered unacceptable.  If Limit Levels were exceeded, the relevant part of the works should not be continued without implementation of immediate remedial action, including a critical review of plant and working methods.

The EAP should lay down the systematic procedures for implementation in case exceedances of A/L Levels and environmental complaints in order to timely address, investigate and resolve such incidents and minimise their recurrence.  The EAP should define the action under specific conditions, i.e. exceedances of A/L Levels, and trigger the relevant parties in the EM&A programme to take the action. 

Environmental audit should include the following components:

·         Regular inspection of site practices should be conducted to assess and ensure the environmental protection and pollution control measures to be in accordance with the EIA recommendations and complied with contract specifications. 

·         Examination of all available information related to the investigation of the nature and cause of actual, potential and cumulative environmental impacts and complaints/ queries;

·         Proposal for remedial measures for resolution of impacts, effective implementation of proposed mitigation measures, documentation and summary of audit findings, and liaison and consultation with the public and concerned parties on the effects of such remedial works; and

·         Enquiries and complaints related to the environmental performance of the Project should be anticipated from individuals and organisations, which should be referred to the ET Leader for investigation and action.  Systematic procedures for environmental complaints should be established and followed.  During the complaint investigation, the DBO Contractor and IEC should facilitate the ET by providing all necessary information. 

2.10.1        Baseline Monitoring

Baseline Monitoring Report should be prepared by the ET and submitted within 4 weeks of completion of baseline monitoring to include all the baseline monitoring data and findings.  The Report should be certified by the ET and verified by the IEC prior to submission to the EPD. 

2.10.2        Impact Monitoring

Monthly EM&A Reports should be prepared by the ET and submitted within 21 days of each reporting month during construction, operational, restoration and aftercare phases to include all the impact monitoring data, findings and recommendations.  Quarterly Summary, Annual Review and Final Review EM&A Reports should be prepared by the ET and submitted within 10 days of each reporting quarter, reporting year and cessation of project phase, respectively, during construction and operational, restoration, and aftercare phases to include all the summary of monitoring trends, findings and recommendations.  These reports should be certified by the ET and verified by the IEC prior to formal submission to the EPD. 

To implement the EM&A programme according to the Construction and Operational Phases, Restoration Phase and Aftercare Phase in which different EM&A requirements should be imposed, the ET and IEC should notify the EPD the completion of EM&A programme for the specific Project phases and request for agreement to cease the EM&A programme. 


3                  Air Quality Monitoring

3.1.1            Air Quality Parameters

Monitoring of the Total Suspended Particulate (TSP) levels shall be carried out by the ET to ensure that any deteriorating air quality could be readily detected and timely action be taken to rectify the situation.  1-hour and 24-hour TSP levels should be measured to indicate the impacts of construction dust on air quality.  The TSP levels shall be measured by following the standard high volume sampling method as set out in the Title 40 of the Code of Federal Regulations, USA, Chapter 1 (Part 50), Appendix B.  Upon approval by the IEC, 1-hour TSP levels can be measured by direct reading methods which are capable of producing comparable results as that by the high volume sampling method, to indicate short event impacts.

All relevant data including temperature, pressure, weather conditions, elapsed-time meter reading for the start and stop of the sampler, identification and weight of the filter paper, and other special phenomena and work progress of the concerned site etc. shall be recorded down in details.

3.1.2            Monitoring Equipment

High volume sampler (HVS) in compliance with the following specifications shall be used for carrying out the 1-hr and 24-hr TSP monitoring:

·   0.6-1.7 m3/min (20-60 SCFM) adjustable flow range;

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

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

·   capable of providing a minimum exposed area of 406 cm2  (63 in2 );

·   flow control accuracy: +/- 2.5% deviation over 24-hr sampling period;

·   equipped with a shelter to protect the filter and sampler;

·   incorporated with an electronic mass flow rate controller or other equivalent devices;

·   equipped with a flow recorder for continuous monitoring;

·   provided with a peaked roof inlet;

·   incorporated with a manometer;

·   able to hold and seal the filter paper to the sampler housing at horizontal position;

·   easy to change the filter; and

·   capable of operating continuously for 24-hr period.

The ET Leader is responsible for provision of the monitoring equipment.  He shall ensure that sufficient number of HVSs with an appropriate calibration kit are available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring.  The HVSs shall be equipped with an electronic mass flow controller and be calibrated against a traceable standard at regular intervals.  All the equipment, calibration kit, filter papers, etc. shall be clearly labeled.

Initial calibration of dust monitoring equipment shall be conducted upon installation and thereafter at bi-monthly intervals.  The transfer standard shall be traceable to the internationally recognised primary standard and be calibrated annually.  The calibration data shall be properly documented for future reference.  All the data should be converted into standard temperature and pressure condition. 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 down in the data sheet.

If the ET Leader proposes to use a direct reading dust meter to measure 1-hr TSP levels, he shall submit sufficient information to the IC and IEC to prove that the instrument is capable of achieving a comparable result as that of the HVS and may be used for the 1-hr sampling.  The instrument should also be calibrated regularly, and the 1-hr sampling shall be determined periodically by HVS to check the validity and accuracy of the results measured by direct reading method.

Wind data monitoring equipment shall also be provided and set up at conspicuous locations for logging wind speed and wind direction near to the dust monitoring locations.  The equipment installation location shall be proposed by the ET Leader and agreed with the ER.  For installation and operation of wind data monitoring equipment, the following points shall be observed:

·   the wind sensors should be installed on masts at an elevated level 10m above ground so that they are clear of obstructions or turbulence caused by the buildings;

·   the wind data should be captured by a data logger and to be downloaded for processing at least once a month;

·   the wind data monitoring equipment should be re-calibrated at least once every six months; and

·   wind direction should be divided into 16 sectors of 22.5 degrees each.

 

In exceptional situations, the ET Leader may propose alternative methods to obtain representative wind data upon approval from the IC and IEC, and agreement from EPD.

3.1.3            Laboratory Measurement/Analysis

A clean laboratory with constant temperature and humidity control, and equipped with necessary measuring and conditioning instruments, to handle the dust samples collected, shall be available for sample analysis, and equipment calibration and maintenance.  The laboratory should be HOKLAS accredited.

If a site laboratory is set up or a non-HOKLAS accredited laboratory is hired for carrying out the laboratory analysis, the laboratory equipment shall be approved by the IC and IEC and the measurement procedures (first measurement) shall be witnessed by the IC and IEC.  The ET Leader shall provide the IC and IEC with one copy of the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix B for his reference.

Filter paper of size 8"x10" shall be labeled before sampling.  It shall be a clean filter paper with no pin holes, and shall be conditioned in a humidity controlled chamber for over 24-hr and be pre-weighed before use for the sampling.

After sampling, the filter paper loaded with dust shall be kept in a clean and tightly sealed plastic bag.  The filter paper is then returned to the laboratory for reconditioning in the humidity controlled chamber followed by accurate weighing by an electronic balance with a readout down to 0.1 mg.  The balance shall be regularly calibrated against a traceable standard. All the collected samples shall be kept in a good condition for 6 months before disposal.

3.1.4            Monitoring Locations

The dust monitoring locations are shown in Table 3.1.  The status and locations of dust sensitive receivers may change after issuing this manual.  If such cases exist, the ET Leader shall propose updated monitoring locations and seek approval from IC and IEC and agreement from EPD on the proposal. 

The ET shall also write to the relevant private owners or owner’s incorporation for their agreement to install the HVS at suitable location at least 3 months before construction works.  The purpose of monitoring (to minimize potential impact and to safeguard the residential) should be clearly stipulated.  The specification, wiring, fixing, maintenance, communication and payment of electricity cost shall be detailed in the letter.  If there is objection from the owner, alternative monitoring location at premises in the vicinity shall be identified and agreed with EPD, IEC and IC. The monitoring location is illustrated in Drawing No. 24315/13/151.

Table 3.1 Description of dust monitoring locations

AML ID

EIA ASR Ref

Location

Land Uses

Monitoring Parameters

AM(D)1

ASR11

Tung Lo Hang

Residential/ Pig Farm

1-hr and 24-hour TSP

AM(D)2

ASR7

Heung Yuen Wai

Residential

1-hr and 24-hour TSP

AM(D)3

ASR1

Wo Keng Shan Tsuen

Residential

1-hr and 24-hour TSP

 

When alternative monitoring locations are proposed, the following criteria, as far as practicable, should be followed:

·   At the site boundary or such locations close to the major dust emission source;

·   Close to the sensitive receptors; and

·   Account for the prevailing meteorological conditions.

The ET Leader shall agree with the IC and IEC on the position of the HVS for installation of the monitoring equipment.  When positioning the samplers, the following points shall be noted:

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

·   no two samplers should be placed less than 2 meter apart;

·   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;

·   a minimum of 2 metres separation from walls, parapets and penthouses is required for rooftop samplers;

·   a minimum of 2 metres separation from any supporting structure, measured horizontally is required;

·   no furnace or incinerator flue is nearby;

·   airflow around the sampler is unrestricted;

·   the sampler is more than 20 metres from the drip-line;

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

·   permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and

·   a secured supply of electricity is needed to operate the samplers.

3.1.5            Baseline Monitoring

The ET Leader shall carry out baseline monitoring at all of the designated monitoring locations for at least 14 consecutive days prior to the commencement of the construction works to obtain daily 24-hr TSP samples.  1-hour sampling shall also be done at least 3 times per day while the highest dust impact is expected.  During the baseline monitoring, there should not be any construction or dust generation activities in the vicinity of the monitoring stations.

In case the baseline monitoring cannot be carried out at the designated monitoring locations during the baseline monitoring period, the ET Leader shall carry out the monitoring at alternative locations which can effectively represent the baseline conditions at the impact monitoring locations.  The alternative baseline monitoring locations shall be approved by the IC and IEC and agreed with EPD.

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

If the baseline level for air quality exceeds the limit level, the ET shall carry out an investigation to determine the cause of the exceedance in consultation with EPD. Regardless of whether the exceedance was caused by poor weather condition (e.g. high API) or as a result of inadequate control measures on construction activities being carried out on other nearby construction sites, a second set of baseline monitoring shall be conducted by the ET to determine an appropriate baseline level for the EM&A programme in agreement with EPD.

Ambient conditions may vary seasonally and shall be reviewed at every three months.  If the ET Leader considers that the ambient conditions have been changed and a repeat of the baseline monitoring is required to be carried out for obtaining the updated baseline levels, the monitoring should be at times when the DBO Contractor's activities are not generating dust, at least in the proximity of the monitoring stations.  Should change in ambient conditions be determined, the baseline levels and, in turn, the air quality criteria, should be revised.  The revised baseline levels and air quality criteria should be agreed with EPD.

3.1.6            Impact Monitoring

The ET Leader shall carry out impact monitoring during the course of the Works.  For regular impact monitoring, the sampling frequency of at least once in every six-days, shall be strictly observed at all the monitoring stations for 24-hr TSP monitoring.  For 1-hr TSP monitoring, the sampling frequency of at least three times in every six-days should be undertaken when the highest dust impact occurs.  The specific time to start and stop the 24-hr TSP monitoring shall be clearly defined for each location and be strictly followed by the DBO Contractor.

In case of non-compliance with the dust criteria, more frequent monitoring exercise, as specified in the Action Plan in Section 3.1.7, shall be conducted within 24 hours after the result is obtained.  This additional monitoring shall be continued until the excessive dust emission or the deterioration in air quality is rectified.

3.1.7            Event and Action

The baseline monitoring results form the basis for determining the air quality criteria for the impact monitoring.  The ET Leader shall compare the impact monitoring results with air quality criteria set up for 24-hour TSP and 1-hour TSP.  Table 3.2 shows the dust criteria, namely Action and Limit levels to be used.  Should non-compliance of the air quality criteria occur, the ET, the IC/IEC and the DBO Contractor shall undertake the relevant action in accordance with the Action Plan in Table 3.3.


Table 3.2 Action and limit levels for dust impact

Parameters

Action

Limit

24-hour TSP Level in µg/m³

For baseline level  200 µg/m³, Action level = (130% of baseline level + Limit level)/2

For baseline level > 200 µg/m³, Action level = Limit level

260

1-hour TSP Level in µg/m³

For baseline level  384 µg/m³, Action level = (130% of baseline level + Limit level)/2

For baseline level > 384 µg/m³, Action level = Limit level

500

 

Table 3.3 Event/Action plan for dust impact

Event

ET

IEC

IC

DBO Contractor

Exceedance of Action Level

1. Exceedance for one sample

·   Identify source

·   Inform IEC and DBO Contractor

·   Repeat measurement to confirm findings

·   Increase monitoring frequency to daily

·   Check monitoring data and DBO Contractor's working methods

·   Notify DBO Contractor for the identification of cause

 

·   Rectify any unacceptable practice

·   Amend working methods if appropriate

2. Exceedance for two or more consecutive samples

·   Identify source

·   Notify IEC and DBO Contractor

·   Repeat measurements to confirm findings

·   Increase monitoring frequency to daily

·   Discuss with IEC/IC for remedial actions required

·   If exceedance continues, arrange meeting with IEC

·   If exceedance stops, cease additional monitoring

·   Review with analysed results submitted by ET

·   Review the proposed remedial measures by DBO Contractor and advise IC accordingly

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed dust problem

·   Ensure remedial measures are properly implemented

·   Submit proposals for remedial actions to IEC within 3 working days of notification

·   Implement the agreed proposals

·   Amend proposal if appropriate


 

Exceedance of Limit Level

1.Exceedance for one sample

·   Identify source

·   Inform IEC and DBO Contractor

·   Repeat measurement to confirm findings

·   Increase monitoring frequency to daily

·   Assess effectiveness of DBO Contractor's remedial actions and keep EPD and IEC/IC informed of the results

·   Check monitoring data and DBO Contractor's working methods

·   Discuss with ET Leader and DBO Contractor potential remedial actions

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed dust problem

·   Ensure remedial measures are properly implemented

 

·   Take immediate action to avoid further exceedance

·   Submit proposals for remedial actions to IEC within 3 working days of notification

·   Implement the agreed proposals

·   Amend proposal if appropriate

2.Exceedance for two or more consecutive samples

·   Identify source

·   Inform IEC, IC, and EPD  the causes and actions taken for the exceedances

·   Increase monitoring frequency to confirm findings

·   Carry out analysis of DBO Contractor’s working procedures to determine possible mitigation to be implemented

·   Assess effectiveness of DBO Contractor’s remedial actions and keep IEC, EPD and IC informed of the results

·   If exceedance stops, cease additional monitoring

·   Discuss amongst IC, ET Leader and DBO Contractor on the potential remedial actions.

·   Review DBO Contractor’s remedial actions whenever necessary to assure their effectiveness and advise IC accordingly

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed dust problem

·   Ensure remedial measures are properly implemented

·   If exceedance continues, consider what activity of the work is responsible and instruct DBO Contractor to stop that activity of work until the exceedance is abated

·   Take immediate action to avoid further exceedance

·   Submit proposals for remedial actions to IEC within 3 working days of notification

·   Implement the agreed proposals

·   Resubmit proposals if problem still not under control

·   Stop the relevant activity of works as determined by the IC until the exceedance is abated

 


3.1.8            Dust Mitigation Measures

The EIA report has recommended dust control and mitigation measures.  The DBO Contractor shall be responsible for the design and implementation of these measures:

·   Dust emission from construction vehicle movement are confined within the worksites area.

·   Watering facilities will be provided at every designated vehicular exit point.

·   Good site practice is recommended during construction phase. Covering with impermeable sheet should be provided for the inactive tipping area.

 

If the above measures are not sufficient to restore the air quality to acceptable levels upon the advice of ET Leader, the DBO Contractor shall liaise with the ET Leader on some other mitigation measures, propose to IC and IEC for approval, and implement the mitigation measures.

3.2.1            Odour Intensity Analysis

Odour Intensity Analysis is conducted by independent trained personnel / competent persons patrolling and sniffing around the Air Sensitive Receiver to detect any odour at the concerned hours.

The independent trained personnel / competent persons shall :

·   have their individual odour threshold of n-butanol in nitrogen gas in the range of 20 to 80 ppb/v required by the European Standard Method (EN 13725).

·   be at least 16 years of age and willing and able to follow instructions.

·   be free from any respiratory diseases.

·   be engaged for a sufficient period to build up and monitor/detect at several monitoring location;

·   not be allowed to smoke, eat, drink (except water) or use chewing gum or sweets 30 min before and during odour intensity analysis;

·   take great care not to cause any interference with their own perception or that of others by lack of personal hygiene or the use of perfumes, deodorants, body lotions or cosmetics;

·   not communicate with each other about the results of their choices.

At least three independent trained personnel / competent persons shall be selected to form a patrol team to conduct the odour intensity analysis, who should participated in a set of screening tests.

Subject to the prevailing weather forecast condition, odour intensity analysis shall be conducted by independent trained personnel / competent persons at the downwind locations. During the analysis, the sequence should start from less odorous locations to stronger odorous locations.

The independent trained personnel / competent persons shall use their nose (olfactory sensors) to sniff odours at different locations. The main odour emission sources and the areas to be affected by the odour nuisance shall be identified.

The perceived odour intensity is to be divided into 5 levels which are ranked in the descending order as follows:

·   0 - Not detected. No odour perceived or an odour so weak that it can not be easily characterised or described;

·   1 - Slight Identifiable odour, and slight chance to have odour nuisance;

·   2 - Moderate Identifiable odour, and moderate chance to have odour nuisance;

·   3 - Strong Identifiable,  likely to have odour nuisance;

·   4 - Extreme Severe odour, and unacceptable odour level.

The independent trained personnel / competent persons shall record the findings including odour intensity, odour nature and possible odour sources, and also the local wind speed and direction at each location. In addition, some relevant meteorological data such as daily average temperature, and daily average humidity, on that surveyed day shall be obtained from the Hong Kong Observatory Station for reference.

3.2.2            Odour Patrol

Apart from odour intensity analysis, routine odour patrol by competent persons shall also be conducted to detect odour nuisance.

3.2.3            Odour Intensity Analysis / Odour Patrol Locations

The odour intensity analysis and odour patrol locations are shown in Table 3.4. The status and locations of air sensitive receivers may change after issuing this manual.  If such cases exist, the ET Leader shall propose updated monitoring locations and seek approval from IC and IEC and agreement from EPD on the proposal.  The monitoring location is illustrated in Drawing No. 24315/13/151.

Table 3.4 Description of odour monitoring locations

AML ID

EIA ASR Ref

Location [1]

Land Uses

Monitoring Parameters

AM(O)1

ASR1

Wo Keng Shan Tsuen

Residential

Odour Intensity

AM(O)2

ASR2

Village houses at Junction of Ng Chow Road and Wo Keng Shan Road

Residential

Odour Intensity

AM(O)3

ASR13

Nga Yiu Ha

Residential

Odour Intensity

AM(O)4

ASR14

Ping Yeung

Residential

Odour Intensity

AM(O)5

ASR10

Lin Ma Hang

Residential

Odour Intensity

AM(O)6

ASR27

Tong To Shan Tsuen [2]

Only if it is occupied by residents

Odour Intensity

Remark:

[1] Odour odour intensity analysis and odour patrol shall only be conduced for the downwind monitoring locations.

[2] Tong To Shan Tsuen is currently a derelict isolated single house.

 

3.2.4            Event and Action

Table 3.5 shows the Action and Limit levels to be used, and the patrol frequency is listed in Table 3.6.  Should non-compliance of the air quality criteria occur, the ET, the IC/IEC and the DBO Contractor shall undertake the relevant action in accordance with the Action Plan in Table 3.7.

Table 3.5 Action and limit levels for odour nuisance

Parameters

Action

Limit

Odour Nuisance (from odour intensity analysis or odour patrol)

·  When two documented complaint are received; or

·  Odour Intensity of 2 is measured from odour intensity analysis.

·  Five or more consecutive geninue documented complaints within a week; or

·  Odour Intensity of 3 or above is measured from odour intensity analysis.

 

 


Table 3.6 Odour Intensity Analysis and Odour Patrol Frequency

Routine Mode

Action Level

Limit Level

Odour Patrol :

Once every six days during the following period:

·  early morning; and

·  peak tipping hour (e.g. 11:00am),

 

Odour Intensity Analysis :

Quarterly during the following period:

·  early morning; and

·  peak tipping hour (e.g. 11:00am),

 

Daily odour patrol.

 

Weekly odour intensity analysis for 2 period during:

·  early morning; and

·  peak tipping hour (e.g. 11:00am)

Daily odour patrol.

 

Daily odour intensity analysis for 2 period during:

·  early morning; and

·  peak tipping hour (e.g. 11:00am)

 

Table 3.7 Event/Action plan for odour nuisance

Event

ET

IEC

IC

DBO Contractor

Action Level

·   Identify source

·   Inform IEC and DBO Contractor

·   If nuisance stops or external source has been identified, resume monitoring to routine mode

·   Recommend precautionary measures

·   Review submissions and reports from ET

·   Notify DBO Contractor

·   Ensure implementation of precautionary measures

 

·   Rectify any unacceptable practice

·   Review the operation of odour enhancement facilities at leachate treatment plants

·   Amend working methods if appropriate

·   Carry out precautionary measures

Limit Level

·   Identify source

·   Inform IEC, and IC, the causes and actions taken for the nuisance

·   Carry out analysis of DBO Contractor’s working procedures to determine possible mitigation to be implemented

·   Assess effectiveness of DBO Contractor’s remedial actions and keep IEC, EPD and IC informed of the results

·   If nuisance stops or external source has been identified, resume monitoring to routine mode

·   Discuss amongst IC, ET Leader and DBO Contractor on the potential remedial actions.

·   Review DBO Contractor’s remedial actions whenever necessary to assure their effectiveness and advise IC accordingly

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed odour nuisance

·   Ensure remedial measures are properly implemented

·   If nuisance continues, instruct DBO Contractor to stop that activity of work suspected to be the origin of the nuisance source until the nuisance is abated

·   Take immediate action to avoid further nuisance

·   Submit proposals for remedial actions to IEC within 3 working days of notification

·   Proposals include tipping at the far end of the upwind location; thicker daily cover can be arranged in case odour patrol identify potential odour nuisance; and use of immediate soil cover for sewage sludge, animal waste

·   Implement the agreed proposals

·   Resubmit proposals if problem still not under control

 

3.3.1            Stack Discharge from ASP, Flare and LFG Power Generator

·   The maximum allowable discharge limit for ASP, flare and LFG power generator should be specified in the design specification. 

·   Owing to the requirement for the installation of stack, the design requirement shall be submitted to IEC and IC for vetting by the DBO Contractor under the Air Pollution Control (Furnaces, Ovens and Chimneys) (Installation and Alternation) Regulations.

·   Subject to the subsequent EPD’s requirement on chimney installation, once every 3 months regular stack monitoring of vinyl chloride, benzene, TOC, NOx and SO2 shall be carried out to demonstrate compliance during the operations.

·   A monthly monitoring report should be prepared by ET and submitted to IEC and IC for approval.

3.3.2            Odour from Leachate Treatment Facilities

For the proposed leachate treatment plant in NENT Landfill Extension, the overall leachate treatment facilities include:

·   Adopted updated treatment method such as Sequencing Batch Reactor for future leachate treatment.  Provision of ventilated cover for the leachate storage lagoons / tanks and emissions extracted to suitable odour removal filters with odour removal efficiency of 99%. 

·   Ferric nitrate or sodium hypochlorite can be added to oxidise the odourous chemical in the leachate. The pH value of leachate can be controlled to a suitable value from future on-site experiment such that the generation of any odourous H2S and ammonia can be optimised.

·   For the gaseous extraction system, the wind speed immediately above the leachate surface should be kept to minimal (in the order of 1E-3 m/s) such that the odour emission strength from lagoon can be minimised. Suitable treatment system should be provided for odour removal. The ventilated gaseous emission from lagoons should be provided with 5-10 air change per hour for further dilution before discharge.  

·   The notional centre of the future discharge point (e.g. stack) shall be located at a location with maximum setback distance from the ASRs and further away from the notional centre of the lagoons. The location of discharge point and discharge height should be determined at the detailed design stage to ensure that the odour criterion at the ASRs will not be exceeded.

·   The overall arrangement should be investigated in details by the DBO Contractor and agreed with IEC and EPD. As such, the odour emission from the future leachate treatment facilities will be insignificant.

3.3.3            Odour from Waste Transfer Activities

The following are some odour precautionary measures that shall be considered by EPD and FEHD:

·   As an improvement measure to enhance to environmental standard for waste transfer, EPD could take the initiative to recommend others to use enclosed type RCVs (dominantly government vehicles and sludge vehicles).   

·   Clearing / watering of the surface and clearing of the waste water receptor of government RCV is recommended before leaving refuse transfer station or government Refuse Collection Point (FEHD).

3.3.4            Precautionary Odour from Waste Tipping Activities

·   The use of alternative daily cover (less permeable layer) instead of inert material should be considered under worst-case weather condition, subject to EM&A Programme.

·   The use of immediate daily cover for odorous waste such as sewage sludge, animal waste etc. under critical condition should also be considered, subject to EM&A Programme.

·   For the time being, there is no population in the derelict Tong To Shan Tsuen. If there is new residents moving in, thicker daily cover / alternative daily cover should be applied at phase 3 of the extension site such that the emission strength for the night time can be reduced (similar performance as that in the inactive tipping area). Odour patrol at Tong To Shan Tsuen should be arranged during night time / early morning in order to ensure the effectiveness of the measures.

·   In accordance with some reference from New Zealand, odour from active tipping area can be much reduced if the waste is covered by sandwich covering material such that it is confined in a solid/semi solid condition. Such covering material will be acted as sandwich protective layers to block the interaction of waste. Only diffusion mode (small scale) will be present. These would be applied during very hot and stable weather condition. Twice daily covering (mid day and close of business) can be arranged in case odour patrol identify potential odour nuisance, subject to EM&A Programme.

·   During stable and calm weather condition and subject to EM&A programme, tipping could be arranged to further increase the setback distance.

3.3.5            VOC Surface Emission

·   The VOC monitoring requirements are discussed in Section 7. Details will be further established in the Landfill Monitoring Plan (LMP) to be developed by the future DBO Contractor based on EM&A Manual for landfill gas monitoring. 

·   Subject to future engineering design, the arrangement of the landfill gas collection system and surface covering material for inactive tipping area shall be reviewed by DBO Contractor every 5 year to identify any modern technology/arrangement (covering material, LFG well spacing and locations) and the latest WHO/USEPA health-risk criteria.  A working team shall be formulated to review all processes, control practice and extraction system in order to maximise the efficiency of the system.  A review report should be prepared by the DBO Contractor for the submission to IC and IEC on the implementation/arrangement of LFG extraction system. The first review report should be submitted to IC and IEC for agreement before commencement. With a good system to collect LFG (high extraction efficiency), surface release of VOC to the nearby environment can be much reduced or utilised.

·   Maintain a slightly negative pressure within the entire tipping area (by suction). Minimise any potential leakage of LFG to the surrounding by increase the number of gas-extraction wells. Improve the extraction efficiency by checking/reinstate gas wells with abnormally low extraction rate due to blockage/soil movement or sedimentation.

·   Increase the coverage of inactive tipping area with HDPE/plastic sheet which can enhance the anaerobic decomposition (reduce air getting in and VOC leaking out).

·   EM&A will be conducted at ASR to establish the future VOC ambient level one year before (as baseline) and one year after the commissioning of NENT extension. This monitoring work should be carried out in a frequency once every 3 month during the period when the ASP and flare are not in operation (only have the contribution from surface emission). Benzene and vinyl chloride are the key monitoring parameters. By comparing the monitoring data at the boundary and at ASR, the cause of VOC and the general downwind dispersion effect (dilution effect) from the boundary to the ASR can be identified. This monitoring should be repeated by the DBO Contractor once every 5 year and the findings should be incorporated into the landfill gas collection system review report as mentioned above.

·   The monitoring location is listed in Table 3.4 and illustrated in Drawing No. 24315/13/151. This off-site VOC monitoring report shall be submitted to IC and IEC for vetting.

Table 3.8 Off-site Surface gas monitoring locations at ASRs

AML ID

EIA ASR Ref

Location

Land Uses

Monitoring Indicator

AM(V)1

ASR1

Wo Keng Shan Tsuen (West of NENT Extension)

Residential

Benzene and Vinyl Chloride

AM(V)2

ASR3

Cheung Shan Monastery (South of NENT Extension)

Religions

Benzene and Vinyl Chloride

AM(V)3

ASR10

Lin Ma Hang (North of NENT Extension)

Residential

Benzene and Vinyl Chloride

AM(V)4

ASR27

Tong To Shan Tsuen (North-east of NENT Extension)

Only if it is occupied by residents

Benzene and Vinyl Chloride


4                  Noise Monitoring

4.1.1            Construction Noise

Construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq).  Leq30min shall be used as the monitoring parameter for the time period between 0700 and 1900 hours on normal weekdays.  For all other time periods, Leq5min shall be employed for comparison with the Noise Control Ordinance (NCO) criteria.  As supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference. 

4.1.2            Operational and Traffic Noise

The noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level over a period of 30 minutes (LAeq, 30mins) and A-weighted 10% of time over a period of one hour (LA10, 1hr) for operational noise and operational traffic noise, respectively.  As supplementary information for data auditing, statistical results such as LA10, LAeq and LA90 shall also be obtained for reference.

In accordance with the Technical Memorandum (TM) issued under the Noise Control Ordinance (NCO), sound level meters in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications shall be used for carrying out the noise monitoring.  Immediately prior to and following each noise measurement, the accuracy of the sound level meter shall be checked using an acoustic calibrator generating a known sound pressure level at a known frequency.  Measurements may be accepted as valid only if the calibration level from before and after the noise measurement agree to within 1.0dB.

The ET Leader shall be responsible for the provision, installation and maintenance of the monitoring equipment.  He shall ensure that sufficient noise monitoring equipment and associated instrumentation are available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring.  All the equipment and associated instrumentation shall be clearly labelled.  The location of equipment installation should be proposed by the ET Leader and agreed with the IC and EPD in consultation with the IEC.

Noise measurements should not be made in the presence of fog, rain, wind with a steady speed exceeding 5m/s or wind with gusts exceeding 10m/s.  The wind speed shall be checked with a portable wind speed meter capable of measuring the wind speed in m/s.

The ET shall carry out noise monitoring during the construction and operational phases at 3 monitoring stations as shown in Table 4.1 and Drawing No. 24315/13/251.  The status and locations of NSRs may change after issuing this EM&A Manual.  In such cases, the ET Leader should propose updated monitoring locations and seek approval from EPD.


Table 4.1 Noise monitoring locations

Monitoring ID

Location

Type of Monitoring

Monitoring Parameters

Supplementary Information

NM1

Wo Keng Shan Tsuen

Construction & Operation

LAeq, 30mins

LA10 and LA90

NM2

Lin Ma Hang

Construction & Operation

LAeq, 30mins

LA10 and LA90

NM3

Cheung Shan Monastery

Traffic Noise

LA10, 1hr

LAeq and LA90

 

When alternative monitoring locations are proposed, the monitoring locations should be chosen based on the following criteria:

·   At locations close to the major site activities which are likely to have noise impacts;

·   Close to the noise sensitive receivers;

·   For monitoring locations in the vicinity of the sensitive receivers, care should be taken to avoid disturbance to the occupants during monitoring.

The monitoring station shall normally be at a point 1m from the exterior of the sensitive receivers building facade and be at a position 1.2m above the ground.  If there is problem with access to the normal monitoring position, an alternative position may be chosen, and a correction to the measurements shall be made.  For reference, a correction of +3dB(A) shall be made to the free field measurements.  The ET Leader shall agree with the IEC on the monitoring positions and the corrections adopted.  Once the positions for the monitoring stations are chosen, the baseline monitoring and the impact monitoring shall be carried out at the same positions.

The ET shall carry out baseline noise monitoring prior to the commencement of the operation of landfill.  The continuous baseline monitoring shall be carried out daily for a period of at least two weeks in a sample period of 5 minutes or 30 minutes.  A schedule on the baseline monitoring shall be submitted to the IC and IEC for approval before the monitoring starts.

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

During normal construction working hour (0700-1900 Monday to Saturday), monitoring of Leq30min noise levels (as 6 consecutive Leq5min readings) shall be carried out at the agreed monitoring locations once every week. 

If a school exists near the construction activity, noise monitoring shall be carried out at the monitoring stations for the schools during the school examination periods.  The ET Leader shall liaise with the school’s personnel and the Examination Authority to ascertain the exact dates and times of all examination periods during the course of the contract.

In case of non-compliance with the construction noise criteria, more frequent monitoring as specified in the Event and Action Plan shall be carried out.  This additional monitoring shall be continued until the recorded noise levels are rectified or proved to be irrelevant to the construction activities.

A schedule on the compliance monitoring shall be submitted to the IEC and IC for approval before the monitoring starts.  Sample data sheet for construction noise measurements is given in Appendix C2.

During normal operational working hours, monitoring of LAeq, 30min noise levels (as six consecutive LAeq, 5min readings) shall be carried out at the agreed monitoring locations once every week in accordance with the methodology in the TM. 

Other noise sources such as road traffic and construction activities may make a significant contribution to the overall noise environment.  Therefore, the results of noise monitoring activities shall take into account such influencing factors, which may not be present during the baseline monitoring period.

In case of non-compliance with the operational noise criteria, more frequent monitoring as specified in the Event and Action Plan shall be carried out.  This additional monitoring shall be continued until the recorded noise levels are rectified or proved to be irrelevant to the operational activities.

During normal operational working hours, monitoring of LA10, 1hr noise levels shall be carried out at the agreed monitoring locations once every week in accordance with the methodology in the Section III of the “Calculation of Road Traffic Noise, 1998”. 

The operational traffic noise monitoring will be measured in term of the A-weighted L10 within the peak traffic hour for each designated noise monitoring location.  Measurements were paused if noise detected from other non-traffic activities became dominant.

In case of non-compliance with the traffic noise criteria, more frequent monitoring as specified in the Event and Action Plan shall be carried out.  This additional monitoring shall be continued until the recorded noise levels are rectified or proved to be irrelevant to the operational activities.


The Action and Limit levels for construction, operational and traffic noise are defined in Tables 4.2-4.4.  Should non-compliance of the criteria occur, actions in accordance with the Event and Action Plan in Tables 4.5-4.6 shall be carried out. 

Table 4.2     Action and limit levels for construction noise

Time Period

Action Level

Limit Level

0700 - 1900 hours on normal weekdays

 

When one documented complaint is received

75 dB(A)*

If works are to be carried out during restricted hours, the conditions stipulated in the construction noise permit issued by the Noise Control Authority have to be followed.

* Reduce to 70dB(A) for schools and 65dB(A) during school examination periods.

 

Table 4.3  Action and limit levels for operational noise

Time Period

Action Level

Limit Level

0700-1900 on all days

When one documented complaint is received

60 dB(A) *

1900-2300 on all days

60 dB(A) *

2300-0700 on all days

50 dB(A) *

* Only apply to operational noise without road traffic and construction activities noise.

 

Table 4.4  Action and limit levels for traffic noise

Time Period

Action Level

Limit Level

Hotel, hostels & All domestic premises including temporary housing accommodation

When one documented complaint is received

70 dB(A)

Schools & Place of public Worship

65 dB(A)

 


Table 4.5  Event and action plan for construction noise

Event

ET

IEC

IC

DBO Contractor

Exceedance of Action Level

·   Identify source, investigate the causes of exceedance and propose remedial measures;

·   Notify IEC and DBO Contractor;

·   Report the results of investigation to IEC, IC and DBO Contractor;

·   Discuss with DBO Contractor and formulate remedial measures;

·   Increase monitoring frequency to check mitigation effectiveness.

·   Review the analysed results submitted by ET;

·   Review the proposed remedial measures by DBO Contractor and advise IC accordingly;

·   Supervise the implementation of remedial measures.

·   Confirm receipt of notification of failure in writing;

·   Notify DBO Contractor;

·   Require DBO Contractor to propose remedial measures for the analysed noise problem;

·   Ensure remedial measures are properly implemented. 

·   Submit noise mitigation proposals to IEC;

·   Implement noise mitigation proposals.

Exceedance of Limit Level

·   Identify source;

·   Inform IEC, IC, EPD and DBO Contractor;

·   Repeat measurements to confirm findings;

·   Increase monitoring frequency;

·   Carry out analysis of Contractor’s working procedures to determine possible mitigation to be implemented;

·   Inform IEC, IC and EPD the causes and actions taken for exceedances;

·   Assess effectiveness of DBO Contractor’s remedial actions and keep IEC, EPD and IC informed of the results;

·   If exceedance stops, cease additional monitoring.

·   Discuss amongst IC, ET, and DBO Contractor on the potential remedial actions;

·   Review DBO Contractors remedial actions whenever necessary to assure their effectiveness and advise IC accordingly;

·   Supervise implementation of remedial measures.

·   Confirm receipt of notification of failure in writing;

·   Notify DBO Contractor;

·   Require DBO Contractor to propose remedial measures for the analysed noise problem;

·   Ensure remedial measures properly implemented;

·   If exceedance continues, consider what portion of the work is responsible and instruct DBO Contractor to stop that portion of works until the exceedance is abated.

·   Take immediate action to avoid further exceedance;

·   Submit proposals for remedial actions to IEC  within 3 working days of notification;

·   Implement the agreed proposals;

·   Resubmit proposals if problem still not under control;

·   Stop the relevant portion of works as determined by IC until the exceedance is abated.

 


Table 4.6  Event and action plan for operational and traffic noise

Event

ET

IEC

IC

DBO Contractor

Exceedance of Action Level

·   Notify IEC and DBO Contractor

·   Carry out investigation

·   Report the results of investigation to IEC and the DBO Contractor

·   Discuss with the DBO Contractor and formulate remedial measures

·   Increase monitoring frequency to check mitigation measures

·   Review with analysed results submitted by ET

·   Review the proposed remedial measures by DBO Contractor and advise IC accordingly

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed noise problem

·   Ensure remedial measures are properly implemented

·   Submit noise mitigation proposals to IEC

·   Implement noise mitigation proposals

Exceedance of Limit Level

·   Identify source

·   Notify IEC, IC, EPD and DBO Contractor

·   Repeat measurement to confirm findings

·   Increase monitoring frequency

·   Carry out analysis of DBO Contractor’s working procedures to determine possible mitigation to be implemented

·   Inform IEC, IC, and EPD the causes and actions taken for the exceedances

·   Assess effectiveness of DBO Contractor’s remedial actions and keep IEC, EPD and IC informed of the results

·   If exceedance stops, cease additional monitoring

·   Discuss amongst IC, ET Leader and DBO Contractor on the potential remedial actions.

·   Review DBO Contractor’s remedial actions whenever necessary to assure their effectiveness and advise IC accordingly

·   Supervise the implementation of remedial measures

·   Confirm receipt of notification of exceedance in writing

·   Notify DBO Contractor

·   Require DBO Contractor to propose remedial measures for the analysed noise problem

·   Ensure remedial measures are properly implemented

·   If exceedance continues, consider what activity of the work is responsible and instruct DBO Contractor to stop that activity of work until the exceedance is abated

·   Take immediate action to avoid further exceedance

·   Submit proposals for remedial actions to IEC within 3 working days of notification

·   Implement the agreed proposals

·   Resubmit proposals if problem still not under control

·   Stop the relevant activity of works as determined by the IC until the exceedance is abated


The DBO Contractor shall be responsible for implementation of the noise control and mitigation measures during operational phase, which shall include, but not limited to, the following:

·   Quiet equipment and construction method should be employed;

·   Only well-maintained plant shall be operated on site and plant shall be serviced regularly during the construction work;

·   Machines and plant that may be in intermittent use (such as breakers) shall be shut down between work periods or should be throttled down to a minimum;

·   Mobile plant shall be sited as far away from NSRs as possible;

·   Material stockpiles and other structures shall be effectively utilised, where practicable, to screen noise from on-site construction activities;

·   Silencers or mufflers on construction equipment should be properly fitted and maintained during the construction works.


5                  Water Quality Monitoring

Potential water pollution sources arising from construction activities include sources mainly from land-based activities, such as construction site runoff; sewage effluent due to workforce on site; accidental spillage of chemical; drainage diversion; and groundwater seepage.

Potential water pollution sources arising from operational include sources mainly from land-based activities, such as seepage of leachate, accidental Leakage of leachate and erosion.

The EIA Report has assessed the water quality impacts caused by the construction and operation of NENT Landfill Extension.  Mitigation measures have been recommended in the EIA to ensure compliance with the relevant legislative requirements.  These mitigation measures are summarised in following sections. An implementation schedule of the recommended mitigation measures is presented in Appendix C3.

5.2.1            Construction Phase

5.2.1.1             Construction Site Runoff

In accordance with the Practice Note for Professional Persons on Construction Site Drainage, Environmental Protection Department, 1994 (ProPECC PN 1/94), and DSD Technical Circular TC14/2000, construction phase precautionary measures as presented in Appendix C3 shall be implemented where necessary.  By adopting the above precautionary measures with Best Management Practices (BMPs) it is anticipated that the impacts of runoff from the construction site will be reduced to satisfactory levels before discharges.

The construction runoff discharged from the landfill site shall fully comply with the standards stated in Section 5.2 of the EIA report, otherwise the discharge shall be collected and conveyed to the on-site leachate treatment plant.

5.2.1.2             Sewage from Workforce

Portable chemical toilets and sewage holding tanks will be provided for handling the sewage generated by the workforce.  A licensed contractor will be employed to provide appropriate and adequate portable toilets and be responsible for appropriate disposal and maintenance.

5.2.1.3             Accidental Spillage of Chemical

Any service workshops and maintenance facilities will be located within a bunding area, and sumps and oil interceptors will be provided. Maintenance of equipment involving activities with potential for leakage and spillage will only be undertaken within the areas appropriately equipped to control these discharges.

5.2.2            Operational Phase

5.2.2.1             Contingency Plan on Accidental Leakage of Leachate

Existing Contingency Plan for Groundwater Contamination

The existing Contingency Plan is comprehensive and well-developed and will be used as basis for developing the Contingency Plan for the extension site.  The parameters to be monitored include groundwater level and groundwater quality. The objective of the monitoring programme is to ensure that the trigger levels below are not exceeded.

Ammonia Nitrogen :          5 mg/L

COD :                              30 mg/L

In the event that the above trigger levels are exceeded, the DBO Contractor will implement a Corrective Action Programme, which shall include:

·            groundwater interception and diversion; and

·            groundwater extraction (by active pumping of leachate from leachate and groundwater collection layers) and treatment prior to discharge.

Proposed Modifications to Contingency Plan for Groundwater Contamination

Potential actions to be taken in case of identification of groundwater contamination should also include:

·            Installation of additional ground-water monitoring well;

·            Increased frequency of ground-water quality testing;

·            Installation of ground-water extraction wells to remove contaminated groundwater for treatment;

·            Installation of subsurface barriers, such as bentonite;

·            Detailed investigation of the potential impact to be performed within six months of the first detection of the justified impact.

Contingency Plan for Surface Water Contamination

Surface water monitoring will be conducted to keep the ammonia-nitrogen and COD below the following trigger levels:

Ammonia Nitrogen :          0.5 mg/L

COD :                              30 mg/L

Suspended Solid :             20 mg/L.

In the event that any one of the above parameters was exceeded, the landfill operation should implement a Corrective Action Programme. The key elements shall include:

·            Surface water interception and temporary storage of the contaminated surface water;

·            Installation of surface barriers, such as sand bund along the surface water channel / site boundary to avoid overflow off-site. 

·            Active pumping of the contaminated surface water to the leachate lagoons / leachate recirculation system / on-site leachate treatment plant;

·            Additional monitoring locations will be selected to determine the pollution source;

·            Installation of surface barriers, such as intercepting bund to separate the active and inactive tipping area. 

·            Change of working methods to prevent surface water contamination; and

·            Implementation of diversionary works.

5.2.2.2             Erosion Control

The DBO Contractor shall devise a soil erosion control plan during the detailed design stage so as to define the site-specific measures and procedures (including the specific operation plan, implementation frequency, monitoring procedures, maintenance schedules, etc). Such requirement shall be specified in contract documents. Appendix C3 summarizes the most popular erosion control methods for reference.

5.2.2.3             Surface Water Drainage System

A temporary surface water drainage system to manage runoff will be adopted during construction and operation. It consists of perimeter channels around the site perimeter.  It will collect surface water from higher elevations to lower elevations and ultimately to the  discharge point.  Details of surface water drainage system are included in Appendix C3.

The surface flow discharge from the landfill site shall fully comply with the standards stated in Section 5.2 of the EIA report, otherwise the contaminated surface flow shall be collected and disposed of to the on-site leachate treatment plant.

The DBO Contractor shall develop and operate a programme of monitoring which shall record the progressive generation of leachate at the NENT Landfill Extension in accordance with the following objectives:

·   To determine the level of leachate within the landfill;

·   To determine the quality of leachate arising from the landfill;

·   To determine the quantity of leachate arising from the landfill and being treated;

·   To monitor the quantity and quality of treated leachate from the leachate treatment works before discharging into leachate pipeline connecting to Shek Wu Hui Sewage Treatment Plant;

·   To ascertain the landfill characteristics and effectiveness of the leachate treatment works. 

The leachate monitoring programme shall commence at the start of landfill operations and continue until the issue of the Aftercare Certificate. The programme shall be developed with in-built flexibility to allow for modification during the development of the leachate treatment works and any modifications to the monitoring of the quality and quantity of leachate generated.

5.3.1            Equipment

Routine sampling and on-site measurements of leachate quality shall be carried out with appropriate equipment which include:

·   Portable thermometer, pH and electrical conductivity (EC) meter

·   Sample bottle of glass or PET of volume not less than 1 litre

·   Flowmeters

At the leachate collection point, the submersible pump shall be used to discharge leachate flow from the leachate removal chamber. Level sensors shall be incorporated into the side slope riser pipe for pump control and measurement of leachate level. In addition, a dipstick and measuring tape shall be used to determine (in-situ) normal leachate levels if the level sensor is not operative.

5.3.2            Calibration and Maintenance

The DBO Contractor shall ensure that all equipment are calibrated and maintained according to manufacturer’s instructions. Routine maintenance shall be carried out in strict accordance with the manufacturer’s requirements. Where calibration intervals are not specified by the equipment manufacturer, the length of time between calibration periods shall not be greater than 6 months.

An inspection procedure shall be established to ensure that the frequency of maintenance is regularised for each equipment. Results from the monitoring programme shall be used to assist in the ongoing operation of the leachate treatment works to ensure that the facility is being operated under the optimum conditions, and that the leachate discharge complies with the trigger levels specified in Section 5.3.8. 

5.3.3            Procedures

The DBO Contractor shall monitor leachate levels within the landfill using calibrated submersible level sensors incorporated into the side slope riser pipe.

Quantity of raw leachate shall be monitored using in-line flow meters installed in the pipe. The flow meters shall be designed and constructed to determine the volume and rate of leachate leaving the landfill site to an accuracy and precision of within +/- 1%.

At the same locations, the leachate shall also be monitored periodically to assess leachate quality produced within operational areas and after treatment. This shall be achieved using in-line sampling valves/taps. The design and construction of these valves/taps shall be such that samples of leachate of between 1 and 25 litres can be readily and easily obtained without sampling rates being too high resulting in unacceptably-high levels of splashing or too low making the duration of sampling unacceptably long.

The DBO Contractor shall use the groundwater drainage layer to detect any leachate escaping through the liner system. The detection system shall involve daily sampling at the groundwater discharge point (shown as Leachate Leakage Detector) and the groundwater monitoring boreholes.

5.3.4            Analysis Parameters

All leachate samples shall be collected and transported to a HOKLAS accredited laboratory as soon after sampling as possible. Appropriate pre-treatment of samples shall be prepared in respect of the analytical parameters, with due regard to its holding times.

Leachate quality shall be monitored as a feedback to the operation for optimisation of the leachate treatment works and to establish its trend over the life of the landfill. The programmes shall generate data to support the establishment of a procedure for the necessary treatment and safe disposal of effluent from NENT Landfill Extension.

The following parameters shall be measured in accordance with the standards contained within the Specification:

Table 5.1 Suite 1 - Leachate Monitoring :

Programme A

Programme B

Parameters

Detection Limit

Frequency

Parameters

Detection Limit

Frequency

Temperature *

0.1°C

Weekly basis initially and then monthly when settled values are obtained for the first 3 years of NENT Landfill Extension operation

Mg

50 mg/L

Monthly basis initially and then 3 monthly Intervals when settled values are obtained for the first 3 years of NENT Landfill Extension operation

pH *

0.1

Ca

50 mg/L

Electrical conductivity *

1 mS/cm

K

50 mg/L

COD

10 mg/L

Fe

50 mg/L

BOD5

3 mg/L

Ni

1 mg/L

TOC

1 mg/L

Zn

10 mg/L

SS

0.1 mg/L

Mn

1 mg/L

Ammonia-nitrogen

0.2 mg/L

Cu

1 mg/L

Nitrate

0.5 mg/L

Pb

1 mg/L

Nitrite

0.5 mg/L

Cd

0.2 mg/L

Total Nitrogen

0.4 mg/L

 

 

Sulphate

5 mg/L

 

 

Phosphate

0.01 mg/L

 

 

Chloride

0.5 mg/L

 

 

Sodium

50 mg/L

 

 

Alkalinity

1 mg/L

 

 

Volatile fatty Acids

2 mg/L

 

 

* On-site measurement

 

Table 52 Suite 2 - Leachate Monitoring

Parameters

Detection Limit

Parameters

Detection Limit

Frequency

Temperature

0.1°C

Phosphate

0.01 mg/L

Quarterly Basis after the first 3 years of NENT Landfill Extension operation

pH

0.1

Chloride

0.5 mg/L

COD

10 mg/L

Sodium

50 mg/L

BOD5

3 mg/L

Alkalinity

1 mg/L

SS

0.1 mg/L

Fe

50 mg/L

Ammonia-nitrogen

0.2 mg/L

Zn

10 mg/L

Nitrate

0.5 mg/L

Cu

1 mg/L

Total Nitrogen

0.4 mg/L

Cd

0.2 mg/L

 

Sulphate

5 mg/L

 

 

 

Suite 1 (Programme A and Programme B) shall be used to establish the quality of leachate from each collection point (i.e., before and after treatment) for the first 3 years of NENT Landfill Extension operation, and Suite 2 shall be used for routine monitoring thereafter.

For leachate leakage detection, the DBO Contractor shall analyse the samples taken at the groundwater discharge point for ammonia-nitrogen, pH and conductivity. If necessary, COD shall be tested when high ammonia-nitrogen is detected at the groundwater discharge point. Samples shall be stored and preserved according to the guidelines of the approved accredited laboratory.

5.3.5            Frequency and Locations of Sampling

The DBO Contractor shall take raw leachate samples and treated leachate samples. The frequency and sampling locations summarized in Table 5.3.

Table 5.3 Frequency and Locations of Sampling

Program

Frequency

Location

Suite 1, Programme A

Weekly intervals initially and then monthly when settled values are obtained

At new leachate Collection Points (i.e prior to discharging points at raw leachate lagoon for raw leachate monitoring and final effluent holding lagoon for partially treated leachate monitoring)

Suite 1, Programme B

At monthly intervals and then three monthly intervals when settled values are obtained for the first three years of NENT Landfill Extension operation

Suite 2

At quarterly intervals after Suite 1 programme B

 

The DBO Contractor shall monitor levels of leachate continuously using calibrated submersible pressure transducers via data retrieving equipment.  Daily records of leachate production shall be maintained via data logging flow meters for all abstraction of liquid from the site and leachate quantities leaving the site. 

The DBO Contractor shall determine the locations of leachate monitoring points and submit the proposed plan to the Independent Consultant for approval.

5.3.6            Results

All sample containers shall be clearly marked, and identified with relevant sampling information. In addition, all monitoring results and observations made at time of sampling shall be recorded in a field data sheet specifically allocated to that sampling task.  The following information shall be recorded on each sampling visit:

·   Sampling point;

·   Data and time of sample collection;

·   Name of technician carrying out the sampling;

·   Weather conditions and ambient temperature;

·   General appearance, condition and temperature of the water body;

·   Sampling device and method used;

·   Sample preservation used;

·   Storage requirements adopted;

·   Space for listing analytical determinations.

5.3.7            Leachate Leakage Detection

Facilities to detect leakage within a 24-hr period shall be placed in the manner and positions specified and be monitored daily for the presence of leachate or contaminated water.

5.3.8            Trigger Levels

The DBO Contractor shall operate a programme of monitoring with the following objectives:

·   Determine the level of leachate within the landfill;

·   Determine the quality of leachate from the landfill;

·   Determine the quantity of leachate from the landfill.

The DBO Contractor shall monitor the levels of leachate continuously at the leachate collection point through the use of calibrated submersible level sensors via data retrieving equipment. The level of leachate at any point within the landfill shall not exceed 1m height above the top of the primary barrier of the landfill liner system.

The standards for discharge of treated leachate from the leachate treatment works into the pipeline leading into Shek Wu Hui Sewage Treatment Works (SWHSTW) are given in Table 1 of the Water Pollution Control Ordinance (WPCO) Technical Memorandum – Standards for Effluent Discharged into Drainage and Sewerage System, Inland and Coastal Waters prepared by the EPD, with the exception for the following discharge limits. 

Total Nitrogen :

200 mg/L

COD :

2000 mg/L

BOD :

400 mg/L

Ammonia-nitrogen :

5 mg/L

SS :

400 mg/L

 

 

Treated leachate shall be discharged to the leachate pipeline leading to the SWHSTW. The leachate generated by the NENT Landfill Extension has been estimated.  Under normal meteorological condition (i.e. with an average annual rainfall of 1,875 mm, data taken from Ta Kwu Ling Station from 1999 to 2005), the peak leachate flow rate from restored NENT Landfill and NENT Landfill Extension (under fully operation in Year 10) is estimated to be (265+860 =) 1,105 m3 /day in wet season, which is within the design capacity of the existing leachate treatment plant (i.e. 1,200 m3 /day). Nevertheless, daily records shall also be made for the quantity of leachate production.

5.3.9            Corrective Action

If the trigger levels in Section 5.3.8 are exceeded, the DBO Contractor shall implement a Corrective Action Programme, which shall include:

·   Leachate extraction;

·   Phased development and closure to minimise the active area footprint;

·   Temporary geosynthetic covers to minimize infiltration in active cells;

·   Run-on and runoff control systems for active and closed areas;

·   Low permeability final cover system to minimise infiltration during post-closure;

In event that the DBO Contractor detects leachate leakage (i.e. the trigger level is exceeded at the groundwater discharge point), the liquid shall be treated at the leachate treatment plant prior to discharge to the leachate pipeline leading to SWHSTW.

Groundwater Level

5.4.1            Introduction

Groundwater levels shall be monitored over the working life of the site to determine the following information:

·   Natural seasonal variation in groundwater levels;

·   Effects of any ground water abstraction;

·   Identification of hydraulic gradients;

·   Variation caused by the construction, operation or aftercare. 

5.4.2            Equipment

A portable dip meter, not affected by condensation, shall be used to measure water depth and checked before use. The dip meter shall comprise a graduated tape and sonic indicator of water level.

5.4.3            Procedures

Water level measurements shall be carried out prior to any purging or sampling from monitoring holes. 

The DBO Contractor shall take groundwater level measurements relative to a permanent fixed datum at a measured elevation at each location, situated and marked on the monitoring borehole casing or cover. Recorded levels shall be expressed as metres relative to Principal Datum, and the levels checked 3 times prior to recording the measurements.

5.4.4            Frequency and Locations of Sampling

All manual groundwater level measurements shall be carried out at least once a month.

In the event that automatic measuring equipment is installed, the associated data loggers shall be interrogated / downloaded at least on a monthly basis. The automatic monitoring equipment shall be calibrated monthly and periodic manual water level measurements shall be carried out to corroborate the measurements.

Monthly groundwater monitoring shall be carried out at specified points ED1-ED35 in accordance with Drawing No. 24315/13/504 unless otherwise approved by the IC.

5.4.5            Results

All manual water level measurements shall be recorded relative to both monitoring borehole datum and Principal Datum. All automatic monitoring equipment shall be in a form that can be input to computer and displayed in numerical or graphical form.  Results shall include site name; unique monitoring borehole reference or location code; date and water level in metres below monitoring borehole datum and to Principal Datum. 

Groundwater Quality

5.4.6            Equipment

The criteria for selection of appropriate equipment shall depend upon the purpose of the sampling exercise, the site characterisation and the parameters that are to be analysed. This shall be assessed using the following criteria:

·   Required sampling accuracy and precision

·   Sampling frequency;

·   Sampler construction material;

·   Required head;

·   Required discharge rate;

·   Reliability and ease of maintenance, including availability of spares. 

Teflon and/or stainless steel samplers (e.g. bailers) shall be used to sample groundwater.

Where sampling relies on the sample being pumped to the surface via tubing, the tubing used shall be Teflon, Teflon lined, or polypropylene. Bladder pumps shall be used to purge and to sample. Groundwater may be pumped from depths in excess of 100m below ground level, due to the depth to groundwater and the topographic level of the site.

5.4.7            Calibration and maintenance

Before each purging process, field meters shall be calibrated according to manufacturer specifications and the calibration results recorded in a calibration log file. All sampling equipment shall be thoroughly decontaminated as per standard sampling protocol prior to use.

5.4.8            Procedures

The DBO Contractor shall purge a monitoring borehole before a sample is taken in order that representative groundwater is sampled. This process shall be combined with field monitoring of determinants such as electrical conductivity, pH and temperature, so that stable sampling conditions can be achieved. If the water is contaminated it shall be contained and treated as leachate, otherwise abstracted groundwater shall be discharged to the surface water drainage system.

Samples shall be stored and preserved according to the guideline of approved accredited laboratory. Representative groundwater sample shall be collected, in approved receptacles as follows:

·   Sampling containers shall be pre-rinsed with the water being collected, except in the case where specific determinations require preservatives in pre-prepared bottles;

·   Glass containers shall be used for receipt of samples for organic analysis;

·   Polyethylene containers shall be used for other determinants, except trace metals determinants such as mercury;

·   Water shall be poured into sampling bottles carefully until filled completely, unless a specific volume is required by the analytical laboratory;

·   A minimum of one litre sample shall be taken, unless otherwise specified;

·   On-site measurement of EC, pH and temperature shall be carried out;

·   On completion of sampling, portable equipment shall be removed from the borehole, and cleaned prior to use at next installation. 

All sample bottles shall be labelled, samples shall be kept at for degrees centigrade and sent to the laboratory within specified holding times for the analytical methods. Samples shall be sent to the laboratory with appropriate chain-of-custody documentation.

Analysis of samples shall be carried out in accordance with methods described in American Society for Testing and Material (ASTM) or American Public Health Association (APHA) – American Water Works Association (AWWA) – Water Pollution Control Federation (WPCF).

5.4.9            Results

All sample containers shall be clearly marked to show the site name, location and date of sample collection.  All results shall be presented as following:

·   Site name;

·   Unique sampling location reference;

·   Time and date of the sampling;

·   Name of the sampling technician;

·   Weather conditions and air temperature;

·   Appearance, condition and temperature of the water body;

·   Sampling device used;

·   On-site measurements of EC, pH and temperature;

·   Volume of water purged prior to sampling;

·   Physical description of the sample. 

5.4.10         Analysis Parameters

The DBO Contractor shall measure the parameters according to the Table 5.4 in monthly basis.  In the event of contamination being detected in the monthly monitoring programme, additional groundwater monitoring shall be carried out in weekly basis. 


Table 5.4  Groundwater Monitoring

Parameters

Detection Limit

Normal Frequency

Additional Frequency

Temperature

0.1°C

Monthly basis

 

pH

0.1

Monthly basis

Weekly Basis

Electrical conductivity

1 mS/cm

Monthly basis

Weekly Basis

COD

10 mg/L

Monthly basis

Weekly Basis

BOD5

3 mg/L

Monthly basis

Weekly Basis

SS

0.1 mg/L

Monthly basis

Weekly Basis

Ammonia-nitrogen

0.2 mg/L

Monthly basis

Weekly Basis

Nitrate

0.5 mg/L

Monthly basis

-

TKN

0.4 mg/L

Monthly basis

-

Sulphate

5 mg/L

Monthly basis

-

Sulphite

2 mg/L

Monthly basis

-

Phosphate

0.01 mg/L

Monthly basis

-

Chloride

0.5 mg/L

-

Weekly Basis

Iron

50 mg/L

-

Weekly Basis

Zinc

10 mg/L

-

Weekly Basis

Coliform Count

1 cfu/ 100mL

Monthly basis

Weekly Basis

 

5.4.11        Trigger Levels

The DBO Contractor shall propose a permanent monitoring network at the site to include the following:

·   Detailed information on the hydrogeological regime;

·   Details on seasonal groundwater level fluctuations and short-term variations in certain areas;

·   Detailed baseline groundwater quality information;

·   Detailed pumping test data for areas down gradient of the site where contaminants are likely to migrate. 

The DBO Contractor shall monitor groundwater around the site to ensure that the following trigger levels are not exceeded Table 5.1.

5.4.12        Corrective Action

In the event that the above trigger levels are exceeded, the DBO Contractor shall implement a Corrective Action Programme, which shall include:

·   Groundwater extraction and, if necessary, treatment prior to discharge;

·   Groundwater interception and diversion. 

5.5.1            Introduction

The DBO Contractor shall carry out surface water monitoring from the commencement of the works until the issue of the Aftercare Certificate in accordance with the following objectives:

·   To assess the performance of the registered design, where: surface water leaves the site and/or the landfill boundary; surface water leaves an operational area; and surface water leaves areas of potential contamination e.g., waste reception area, vehicle and wheel washing, haul route, vehicle servicing, etc.

·   To ensure no long-term deterioration in surface water quality adjacent to the site;

·   To provide data for the design and to monitor the effectiveness of any remedial measures which may be necessary in the event of excessive leachate migration or liner failure.

Surface water monitoring stations shall be established in and around the site as part of the monitoring programme.

5.5.2            Equipment

For monitoring surface water quality, the DBO Contractor shall use the following sampling and measuring equipment:

·   Varying water sample containers, as appropriate to the type of analysis being determined, fabricated from polyethylene, polypropylene, polycarbonate, aluminium, stainless steel or glass

o        Glass containers for organic constituents, but where major constituents of glass are to be analysed (e.g. sodium, potassium, boron, silicon and trace metallic impurities), glass containers shall not be used.

o        Polyethylene containers shall not be used for trace metallic impurities such as mercury.

·   Silicon sieve/disposable filters for removal of suspended solids

·   Thermometer with a range of 0-50°C

·   Digital pH meter

·   Electrical conductivity meter

A clamp, pole or string shall be attached to the bottle if the water poses a threat to the sampling technician or if direct contact is likely to be made with skin. However, in all situations, gloves shall be worn as a matter of routine when sampling potentially-contaminated water.

The following equipment or the approved equivalents shall be provided for monitoring flow:

·   IS32 flow monitor complete with Druck transducer capable of measuring parameters of depth and velocity at specified intervals, with trip mode built-in.

·   Velocity calibrator – Montec 3013 portable Doppler measurement for in-situ calibrations of velocity. A 1.25m logging wand shall be used for recording in-situ measurements.

·   Monitoring software – specifically designed for use with IS32 and Montec 3013, to produce depth, velocity and discharge graphs, as well as tabulated data.

5.5.3            Calibration and Maintenance

Clean, pre-conditioned/washed sample containers shall be used during the sampling programme. Sample containers shall be used only once with the exception of glass containers appropriately decontaminated at the analytical laboratory prior to use. All sampling equipment including open-mouthed collection vessels (buckets and cans) and sieves shall be decontaminated prior to use between sample points to prevent cross contamination. Decontamination procedures involve the use of laboratory grade detergent and rinsing in de-ionized water. Sample bottles that contain chemical preservatives shall not be rinsed or cleansed in any way.

Thermometers shall be rinsed with de-ionized water and then wiped with disposable towels immediately after use before being replaced in the carrying case.

All flow measuring equipment shall be calibrated according to the manufacturer’s specifications.

5.5.4            Procedures

The DBO Contractor shall undertake sampling of surface water quality with reference to the following documents:

·   British Standard Institution (BSI) BS6068: 1981 Water Quality Sampling Section 6.1. Guidance on the Design of Sampling Programmes

·   International Standard Organisation (SO) ISO 5667-6 1990 Guidance on Sampling of Rivers and Streams


·   BSI, BS 6068 1983 Water Quality Section 6.2 Guidance on Sampling Techniques. Health and Safety Executive

·   BSI, BS 6068: 1986 Water Quality Section 6.3 Guidance on the Preservation and Handling of Samples (International Standards Organisation ISO 5667/3 – 1985 Water quality – Sampling – Part 3: Guidance on the Preservation and Handling of Samples).

Before sampling, the flow rate of the stream/river shall be determined and the water and air temperature, pH and electrical conductivity shall be measured and recorded.

All the precautions outlined in the Specification for avoiding contamination during sampling shall be taken, for example, pre-rinsing sampling containers (excluding those containers which are preserved by certain type of chemicals) with the surface water to be collected. In addition, appropriate health and safety precautions including the wearing of protective waterproof gloves shall be followed.

In general, samples shall be collected from within 500mm of the water surface. Samples shall be collected within an open mouthed vessel with the lip pointing upstream. The sample shall be filtered as appropriate. Alternatively the sample shall be collected directly into the sample container. Sampling of the surface film layer shall be avoided during the sampling programme.

During sample collection, care shall be taken so that air is not introduced into the samples thereby altering the relative compositions of the determinants. Once the sample bottle is filled to the top with no remaining air space the lid shall be securely screwed on. Where samples are to be preserved with acid or alkalis prior to transport to the laboratory, the sample bottles shall be filled to the level specified by the analytical laboratory.

Samples shall be transported to the laboratory for analysis as soon as possible after the sample is collected, since the longevity of some of the sample determinants is limited. All samples shall be stored at 4°C and transported to the laboratory within 48 hours from sampling.

Analyses shall be carried out in accordance with methods described in ASTM or APHA – AWWA – WPCF Standard.

Flow measurements shall also be taken continuously using automatic logging equipment.

5.5.5            Analysis Parameters

The DBO Contractor shall measure the all parameters according to Table 5.5 in monthly basis.  In the event of contamination being detected in the monthly monitoring programme, additional surface water monitoring shall be carried out in weekly basis.

Table 5.5  Surface Water Monitoring

Parameters

Detection Limit

Normal Frequency

Additional Frequency

pH

0.1

Monthly basis

Weekly Basis

Electrical conductivity

1 mS/cm

Monthly basis

Weekly Basis

Alkalinity

1 mg/L

Monthly basis

-

COD

10 mg/L

Monthly basis

Weekly Basis

BOD5

3 mg/L

Monthly basis

Weekly Basis

TOC

1 mg/L

Monthly basis

Weekly Basis

SS

0.1 mg/L

Monthly basis

Weekly Basis

Ammonia-nitrogen

0.2 mg/L

Monthly basis

Weekly Basis

TKN

0.4 mg/L

Monthly basis

-

Nitrate

0.5 mg/L

Monthly basis

-

Sulphate

5 mg/L

Monthly basis

-

Sulphite

2 mg/L

Monthly basis

-

Phosphate

0.01 mg/L

Monthly basis

-

Chloride

0.5 mg/L

Monthly basis

-

Sodium

50 mg/L

Monthly basis

-

Mg

50 mg/L

Monthly basis

-

Ca

50 mg/L

Monthly basis

-

K

50 mg/L

Monthly basis

-

Fe

50 mg/L

Monthly basis

Weekly Basis

Ni

1 mg/L

Monthly basis

-

Zn

10 mg/L

Monthly basis

Weekly Basis

Mn

1 mg/L

Monthly basis

-

Cu

1 mg/L

Monthly basis

-

Pb

1 mg/L

Monthly basis

-

Cd

0.2 mg/L

Monthly basis

-

Coliform Count

1 cfu/ 100mL

Monthly basis

Weekly Basis

Oil and Gease

5 mg/L

Monthly basis

-

 

Surface water flow shall be monitored continuously using automatic data logging equipment. Following periods of heavy rainfall, flow shall be monitored weekly and more frequently to determine peak discharge rates.

5.5.6            Locations of Sampling

Monthly surface water monitoring shall be carried out at specified points WM1 (Upstream of Lin Ma Hang) and WM2 (Ping Yuen River, i.e existing SP1 monitoring station) in accordance with Drawing No. 24315/13/504 unless otherwise approved by the IC. The sampling points shall be readily accessible and sampling shall be obtained from a flow that is moderate and steady. Turbulent flowing streams or stagnant polls shall be avoided.

5.5.7            Results

Upon completion of each sampling exercise, the sample containers shall be clearly labelled with site name; sampling location reference; date and time of collection and sample number. 

In addition, the sampling technician shall record any abnormality which may affect water quality in their record notebooks.  The sampling record shall include the following details:

·   Sampling site and sampling point;

·   Date and time of collection;

·   Name of sampling technician;

·   Weather conditions and air temperature;

·   Appearance, condition and temperature of the water body;

·   Sampling method and sampling device used;

·   Sample preservation;

·   Storage requirements;

·   List of parameters (with space for the analytical results). 

5.5.8            Trigger Levels

The DBO Contractor shall conduct the surface water monitoring programme in order to keep ammonia-nitrogen and COD below the following trigger levels:

Ammonia-nitrogen :           0.5mg/L

COD :                              30 mg/L

In addition, suspended solids concentrations for surface waters leaving the site shall not exceed 20mg/L. 


5.5.9            Corrective Action

In the event that these trigger levels are exceeded, the DBO Contractor shall implement a Corrective Action Programme, which shall include:

·   Sampling upstream into landfill to trace the source;

·   Surface water interception and treatment prior to discharge;

·   Changes to working methods to prevent surface water contamination;

·   Diversionary works. 

Where analytical results indicate the presence of contamination, additional monitoring locations shall be selected to determine the pollution source. The DBO Contractor shall implement procedures in accordance with the corrective action plan to mitigate any contamination sources identified, or discharge the surface water to the leachate treatment plant.

The Action and Limit levels for surface and ground water quality are defined in Table 5.6 and Table 5.7.  Should non-compliance of the criteria occur, action in accordance with the Action Plan in Table 5.8 shall be carried out.

Table 5.6     Action and Limit Levels for Surface Water Quality

Parameters

Action

Limit

Construction

DO in mg L-1

(Surface, Middle & Bottom)

Surface and Middle

5 percentile of baseline data for surface and middle layer

 

Bottom

5 percentile of baseline data for bottom layer

Surface and Middle

4 mg L-1  or

1%-ile of baseline data for surface and middle layer 

Bottom

2 mg L-1 or

1%-ile of baseline data for bottom layer

pH (depth averaged), Turbidity in NTU (depth-averaged), SS in mg L-1 (depth-averaged)

95 percentile of baseline data or 120% of upstream control station's pH, Turbidity, SS at the same tide of the same day

99 percentile of baseline or 130% of upstream control station's pH, Turbidity, SS at the same tide of the same day

Operation

COD, Ammonia-nitrogen

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