7                     Waste Management Implications

Introduction

7.1               Waste management will be the contractor’s responsibility to ensure that all wastes produced during the construction of the Project are handled, stored and disposed of in accordance with the recommended good waste management practices and EPD’s regulations and requirements.

 

7.2               Other waste materials generated during the construction activities, such as construction and demolition (C&D) materials, chemical wastes and general refuse from the workforce, are recommended to be audited at regular intervals (at least quarterly) to ensure that proper storage, transportation and disposal practices are being implemented. This monitoring of waste management practices will ensure that these solid and liquid wastes generated during construction are not disposed of into the surrounding marine waters or places. The Contractor will be responsible for the implementation of any mitigation measures to minimize waste or redress problems arising from the waste materials.

 

7.3               The Contractor shall prepare and implement an Environmental Management Plan (EMP) in accordance with ETWB TCW No. 19/2005 which describes the arrangements for avoidance, reuse, recovery, recycling, storage, collection, treatment and disposal of different categories of waste to be generated from the construction activities. Such a management plan should incorporate site specific factors, such as the designation of areas for segregation and temporary storage of reusable and recyclable materials. The EMP should be submitted to the Engineer for approval. The Contractor should implement the waste management practices in the EMP throughout the construction stage of the Project. The EMP should be reviewed regularly and updated by the Contractor, preferably in a monthly basis.

 

7.4               Unless otherwise stated, all surplus C&D materials arising from or in connection with the Works shall become the property of the Contractor when it is removed from the Site. The Contractor shall be responsible for devising a system to work for on-site sorting of C&D materials and promptly removing all sorted and process materials arising from the construction activities to minimize temporary stockpiling on-site. The system should be included in the EMP identifying the source of generation, estimated quantity, arrangement for on-site sorting, collection, temporary storage areas and frequency of collection by recycling Contractors or frequency of removal off-site.

Waste Control and Mitigation Measures

7.5               Mitigation measures for waste management are summarized below. With appropriate handling, storage and removal of waste arisings during the construction phase, the potential to cause adverse environmental impacts would be minimized. The implementation schedule of the recommended mitigation measures is presented in Appendix A. During the site inspections, the ET shall pay special attention to the issues relating to waste management and check whether the Contractor has implemented the recommended good site practices and other mitigation measures.

 

Construction Phase

On-site Sorting, Reuse and Recycling of Materials as far as Practicable

7.6               Stockpiling area for long term storage of C&D materials generated at earlier construction stage for reuse or recycle at later stage (such as backfilling of production shafts) may not be available. To minimize the quantity of surplus C&D materials, aggregates and backfilling materials should be recycled from fill banks operated by Civil Engineering and Development Department (CEDD) if the CEDD’s fill bank is still under operation at the time when the contractor is carrying out backfilling.  However, if the fill bank is decommissioned, the Contractor would be required to carry out backfilling using fill materials from his own source.

 

7.7               Grade I/II granite generated from SCS construction would be delivered to Lam Tei Quarry for crushing into aggregate, as an alternative to deliver it to CEDD’s fill bank for processing.

 

7.8               Reusable steel or concrete panel shutters, fencing and hoarding and signboard should be used as a preferred alternative to items made of wood, to minimise wastage of wood. Attention should be paid to WBTC No. 19/2001 - Metallic Site Hoardings and Signboards to reduce the amount of timber used on construction sites. Metallic alternatives to timber are readily available and should be used rather than new timber. Precast concrete units should be adopted wherever feasible to minimize the use of timber formwork.

 

7.9               Prior to export of material from the site, the potential for it to be reused should be assessed. Waste separation methods should be followed to ensure that C&D waste is separated at source. Whenever possible, suitable soft materials should be used for landscaping and fine material should be separated out and used as topsoil.

 

7.10            All waste materials should be segregated into categories covering:

·             excavated materials suitable for reuse on-site;

·             excavated materials suitable for public filling reception facilities;

·             remaining C&D waste for landfill;

·             chemical waste; and

·             general refuse for landfill.

 

7.11            Proper segregation and disposal of construction waste should be implemented. Separate containers should be provided for inert and non-inert wastes.

 

7.12            Sorting is important to recover materials for reuse and recycling. Specific area should be allocated for on-site sorting of C&D materials and to provide a temporary storage area for those sorted materials such as metals, concrete, timber, plastics, glass, excavated spoils, bricks / tiles and waste papers. If area is limited, all C&D materials should at least be sorted on-site into inert and non-inert components. Non-inert materials (C&D waste) such as bamboo, timber, vegetation, packaging waste and other organic materials should be reused and recycled wherever possible and disposed of to designated landfill only as the last resort. Inert materials (public fill) such as concrete, stone, clay, brick, soil, asphalt and the like should be separated and reused in this or other projects (subject to approval by the relevant parties in accordance with the ETWB TCW No. 31/2004) before disposed of at a public filling reception facility operated by CEDD. Steel and other metals should be recovered from demolition waste stream and recycled.

 

7.13            The feasibility of using recycled aggregates in lieu of virgin materials should be rigorously considered during the detailed design and construction stages as stipulated in WBTC No. 12/2002 and ETWB TCW No. 24/2004. In general, recycled aggregates are suitable for use as fill materials in earthworks, road sub-base formation, and drainage works.

 

Good Site Practices

7.14            Adverse impacts related to waste management are not expected to arise, provided that good site practices are strictly followed.  Recommendations for good site practices during the construction activities include:

·             Nomination of an approved person, such as a site manager, to be responsible for good site practices, arrangements for collection and effective disposal to an appropriate facility, of all wastes generated at the site;

·             Training of site personnel in proper waste management and chemical waste handling procedures;

·             Develop and provide toolbox talk for on-site sorting of C&D materials to enhance worker’s awareness in handling, sorting, reuse and recycling of C&D materials;

·             Provision of sufficient waste disposal points and regular collection for disposal;

·             Appropriate measures to minimise windblown litter and dust during transportation of waste by either covering trucks or by transporting wastes in enclosed containers;

·             Regular cleaning and maintenance programme for drainage systems, sumps and oil interceptors; and

·             A recording system for the amount of wastes generated, recycled and disposed of (including the disposal sites).

 

Waste Reduction Measures

7.15            Good management and control can prevent the generation of a significant amount of waste.  Waste reduction is best achieved at the planning and design stage, as well as by ensuring the implementation of good site practices.  Recommendations to achieve waste reduction include: 

·             Sort C&D waste from demolition of the existing building structures to recover recyclable portions such as metals;

·             Segregation and storage of different types of waste in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal;

·             Encourage collection of aluminium cans, PET bottles and paper by providing separate labelled bins to enable these wastes to be segregated from other general refuse generated by the work force;

·             Any unused chemicals or those with remaining functional capacity shall be recycled;

·             Use of reusable non-timber formwork, such as in casting the tunnel box sections, to reduce the amount of C&D material;

·             Proper storage and site practices to minimise the potential for damage or contamination of construction materials; and

·             Plan and stock construction materials carefully to minimise amount of waste generated and avoid unnecessary generation of waste.

 

7.16            In addition to the above measures, specific mitigation measures are recommended below for the identified waste arisings to minimise environmental impacts during handling, transportation and disposal of these wastes.  

 

Construction and Demolition Material

7.17            In order to minimise impacts resulting from collection and transportation of C&D material for off-site disposal, the excavated materials arising from the SCS construction, PTW upgrading works and SCISTW expansion should be reused on-site as far as practicable. Surplus inert C&D material should be disposed of at public fill reception facilities for other beneficial uses.  C&D waste, such as wood, steel and other metals should be reused or recycled and, as a last resort, disposed of to landfill. It is recommended that a suitable area be designated to facilitate the sorting process and a temporary stockpiling area would be required for the separated materials. The Contractor should identify these areas in the WMP.

 

7.18            In order to monitor the disposal of public fill and C&D waste at public filling facilities and landfills, respectively, and to control fly tipping, a trip-ticket system should be included as one of the contractual requirements and implemented by an Environmental Team undertaking the Environmental Monitoring and Audit work.  An Independent Environmental Checker should be responsible for auditing the results of the system.

 

7.19           When disposing C&D material at a public filling area, it shall be noted that the material shall only consist of soil, rock, concrete, brick, cement plaster/mortar, inert building debris, aggregates and asphalt. The material shall be free from marine mud, household refuse, plastic, metals, industrial and chemical waste, animal and vegetable matter, and other material considered to be unsuitable by the filling supervisor.

 

7.20            Bentonite slurries used in diaphragm wall and bore-pile construction should be reconditioned and reused wherever practicable.  The disposal of residual used bentonite slurry should follow the good practice guidelines stated in ProPECC PN 1/94 “Construction Site Drainage” and listed as follows:

·             If the disposal of a certain residual quantity cannot be avoided, the used slurry may be disposed of at the marine spoil grounds subject to obtaining a marine dumping licence from EPD on a case-by-case basis.

·             If the used bentonite slurry is intended to be disposed of through the public drainage system, it should be treated to the respective effluent standards applicable to foul sewers, storm drains or the receiving waters as set out in the Technical Memorandum of Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters.

 

7.21            If excavated material would be stockpiled temporarily on-site, control measures as described in Chapter 2 (Air Quality) and Chapter 4 (Water Quality) should be taken to prevent generation of dust and pollution of stormwater drainage systems.

 

General Refuse

7.22            General refuse should be stored in enclosed bins or compaction units separate from C&D material.  A licensed waste collector should be employed by the contractor to remove general refuse from the site, separately from C&D material.  Preferably an enclosed and covered area should be provided to reduce the occurrence of 'wind blown' light material. 

 

7.23            The removal of waste from the site should be arranged on a daily or at least on every second day by the Contractor to minimise any potential odour impacts, minimise the presence of pests, vermin and other scavengers and prevent unsightly accumulation of waste.

 

7.24            The recyclable component of the municipal waste generated by the workforce, such as aluminium cans, paper and cleansed plastic containers should be separated from other waste. Provision and collection of recycling bins for different types of recyclable waste should be set up by the Contractor. The Contractor should also be responsible for arranging recycling companies to collect these materials.

 

7.25            The burning of refuse on-site is prohibited under the Air Pollution Control Ordinance (APCO) (Cap.311).

 

Sewage

7.26            The workers would be scattered along the proposed tunnel alignment and different work sites. The most cost-effective solution is to provide adequate number of portable toilets at temporary works areas or the PTWs to ensure that sewage from site staff would be properly collected.

 

7.27            Depending on site conditions, land availability, site activities and arrangement, locations and number of portable toilets should be determined by the Contractor during preparation of the Waste Management Plan (WMP).

 

Chemical Wastes

7.28            If chemical wastes are produced at the construction site, the Contractor would be required to register with the EPD as a chemical waste producer and to follow the guidelines stated in the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes. Good quality containers compatible with the chemical wastes should be used, and incompatible chemicals should be stored separately.  Appropriate labels should be securely attached on each chemical waste container indicating the corresponding chemical characteristics of the chemical waste, such as explosive, flammable, oxidizing, irritant, toxic, harmful, corrosive, etc.  The Contractor shall use a licensed collector to transport and dispose of the chemical wastes, to either the approved Chemical Waste Treatment Centre, or another licensed facility, in accordance with the Waste Disposal (Chemical Waste) (General) Regulation.

 

7.29            Suitable containers should be used for specific types of chemical wastes, containers should be properly labelled (English and Chinese in accordance with instructions prescribed in Schedule 2 of the Regulations), resistance to corrosion, stored safely and closely secure. Stored volume should not be kept more than 450 liters unless the specification has been approved by the EPD. Storage area should be enclosed by three sides by a wall, partition of fence that is at least 2 m height or height of tallest container with adequate ventilation and space.

 

7.30            Lubricants, waste oils and other chemical wastes are likely to be generated during the maintenance of vehicles and mechanical equipment. Used lubricants should be collected and stored in individual containers which are fully labelled in English and Chinese and stored in a designated secure place. If possible, such waste should be sent to oil recycling companies, and the empty oil drums collected by appropriate companies for reuse or refill.

 

7.31            No lubricants, oils, solvents or paint products should be allowed to discharge into water courses, either by direct discharge, or as contaminants carried in surface water runoff from the construction site.

 

Excavated Materials and Marine Deposit

7.32            Prior to excavation of soil nearer the ground level, the soil should be collected for laboratory analysis in accordance with the “Guidance Note for Contaminated Land Assessment and Remediation” (refer to as Guidance Note) issued by EPD and the laboratory results should be compared with the Risk-based Remediation Goals (RBRGs) in the Guidance Note for assessing soil contamination.  The impacts as a result of the findings should be evaluated and remedial measures shall be formulated if necessary, the treated soil can then be used as public filling materials.

 

7.33            Marine deposit would be mainly generated from excavation works for upgrading of PTWs and expansion works of SCISTW Prior to excavation of the marine deposit layer, the deposit should be tested in accordance with the ETWB TC(W) No. 34/2002 and the results should be presented in a Preliminary Sediment Quality Report. The marine deposit should be disposed of at the disposal site designated by the Marine Fill Committee (MFC) or Director of Environmental Protection (DEP) depending on the test results.

 

7.34            Silty or clayey materials from alluvium and marine deposit shall be identified at source. Non-contaminated alluvial and marine deposits should be transported by leak proof trucks to eliminate water leakage during transportation to the barging facility for open sea disposal.

 

Operation Phase

Preventive Measures of Sludge Transfer Tanks

7.35            Since the air tightness of tankers highly relies on the effectiveness of rubber seals at the loading openings and unloading doors, odour leakage from tankers are commonly resulted from the aging rubber seals. A preventive maintenance programme should be developed for good maintenance of rubber seals of loading openings and unloading doors of sludge transfer tanks to ensure the tightness of covers and doors. Rubber seals should be regularly replaced within its design life as specified by suppliers.

 

Good Cleaning Practices for Sludge Transfer Tankers

7.36            The vehicles washing facilities should be able to brush the top of tankers. Rotating brushes or other alternative devises should be installed at the upper frame of vehicles washing facilities. If head space is insufficient for installing additional brushes, manual cleaning and brushing the top of tankers should be implemented in the first cleaning stage. Other current cleaning practices for sludge transfer tankers should be continued.

 

Cleaning Practice at Waste Disposal Facilities

7.37            The tanker operators should ensure that the unloaded tankers have no residual sludge deposited on the tank surfaces. After cleaning, the tankers should be dewatered naturally as currently practiced at SCISTW before leaving the disposal facilities to minimize visual impact to road users.

 

7.38            All screenings/grit should be bagged before transportation.

 

7.39            The following good practices should be implemented to minimize odour impact arising from the transportation and disposal of screenings and grit:

·             Plastic bags should be used for storage to avoid direct contact of screenings / grit with the containers.

·             During the transportation to waste disposal facilities, the screenings / grit in skips should be bagged and covered properly to minimize odour emission.

 

7.40            The skips used for transportation of screenings / grit should be maintained clean and be inspected regularly.  Washing of skips should be carried out when contamination with odorous residues is identified.