5.0.0.1 This Section identifies the potential wastes arising from the construction of the Project and assesses the potential environmental impacts of their handling and disposal. Options for reuse, minimization, recycling, treatment, storage, collection, transport and disposal of waste arising from construction were examined. Where appropriate, procedures for waste reduction and management are considered and environmental control measures for avoiding or minimising impacts are recommended.
5.1 Legislation, Policies, Plans, Standards and Criteria
5.1.0.1 The criteria for evaluating potential construction waste management implications are set out in Annex 7 of the EIAO-TM.
5.1.0.2 The following legislation covers, or has some bearing upon, the handling, treatment and disposal of waste of in Hong Kong, and has been used as the assessment criteria:
5.1.0.3 The following documents, guidelines and circulars relate to waste management in Hong Kong:
5.2 Description of Environment
5.2.0.1 Construction activities would result in the generation of a variety of waste which may include:
5.2.0.2 If not properly managed, the handling and disposal of this waste may cause environmental impact and nuisance.
5.2.1 Site Clearance Waste
5.2.1.1 The Project will be partly constructed on hillsides and in rural areas. Site clearance waste generated would therefore generally consist of low graded natural vegetation such as scrub and grass.
5.2.1.2 Site clearance waste would also be generated from the clearance of existing structures of the land resumed for the construction of DBL. These include wastes from clearance of workshops, opened storage sites, village house and temporary structures.
5.2.2 Construction and Demolition Material
5.2.2.1 Construction and demolition material (C&DM) would mainly arise from the viaducts and the demolition of existing structures such as village houses. It includes unwanted materials generated during construction, rejected structures and materials, materials that have been over-ordered and materials which have been used and discarded. C&DM may include:
5.2.2.2 A number of village houses and existing structures may be demolished in Lam Tei. This may result in the generation of demolition material.
5.2.2.3 The Contractor is responsible for the separation of C&DM into re-usable and non-reusable materials, and transfer of these materials to public filling areas or landfills, depending on the type of material and the percentage of inert material. The public fill should be reused on site or disposed of to public filling areas. The non-inert portion of the C&DM (C&D material) should be reused or recycled and, disposal of at landfills as the last resort.
5.2.3 Excavated Materials
5.2.3.1 As indicated in the preliminary construction programme, the main sources of excavated material will be the passage to Ngau Hom Shek which involves the excavation of soil and rock material and also some excavations from the foundation construction along the alignment.
5.2.3.2 Excavated materials are usually inert such as soil and rock, and can normally be reused on site or in public filling areas. For rock material, screening device and a mobile rock crusher could be installed on site for reuse. Waste materials should be segregated into good rock suitable for recycling.
5.2.4 Marine Dredged Materials
5.2.4.1 There would be neither marine works nor marine dredged materials anticipated in this Project.
5.2.5 Chemical Waste
5.2.5.1 The Waste Disposal (Chemical Waste) (General) Regulation defines chemical waste as any substance being scrap material or unwanted substances specified in its Schedule 1 and provides a complete list of such substances. However, substances likely to be generated by construction activities would mainly arise from the maintenance of equipment. These may include, but not be limited to, the following:
5.2.5.2 Chemical waste may pose serious environmental, health and safety hazards if it is not properly managed. These hazard include:
5.2.6 General Refuse
5.2.6.1 Each worksite would generate general refuse including paper and food waste. There is likely to be a concentration of such waste at batching plants on major worksites. The storage of general refuse has the potential to give rise to high environmental impacts. These include odour (if waste is not collected frequently), windblown litter, water quality impacts (if waste enters water bodies), and visual impacts. The refuse may also attract pests and vermin if the storage areas are not well maintained and cleaned regularly. In addition, disposal of waste at sites other than approved waste transfer or disposal facilities, can also lead to environmental impacts.
5.3.0.1 The method for assessing potential waste management impacts during construction follow that presented in Annex 7 and 16 of the EIAO-TM and include the following:
5.3.0.2 This assessment covers the analysis of activities and waste generation and proposal for waste management in the construction and operational stages of the proposed development in DBL.
5.4 Identification, Prediction and Evaluation of Potential Impacts
5.4.0.1 The amount of waste arising from construction and the potential environmental impacts associated with its handling, storage, transport and disposal are discussed below.
5.4.1 Site Clearance Waste
5.4.1.1 The majority of the alignment is either on viaduct or bridges. The need for site clearance would be limited and would consist of small amounts of low graded vegetation, mainly consisting of scrub and grass, demolition and building materials (from temporary structures and village houses) and a small portion of the available topsoil. Demolition of buildings and houses will generate concrete rubble, plastics, metal, glass, asphalt from surfaces, wood and refuse.
5.4.1.2 C&DM from site clearance and demolition works has been estimated based on the amounts of hard paved slab, temporary structures and small houses of up to 3 storeys which are likely to be demolished or cleared. It is estimated that up to 0.47 ha worth of hard paved area will be cleared. Assuming 0.1 m thick of hard paved slab, 465 m3 of material would be generated. Around the DBL area, there are about 480 temporary structures and small houses which will require demolition. Based on the assumption that 40 m3 of C&DM would be produced by the demolition of temporary structures and small houses respectively, 19,200 m3 of C&DM would be generated. In total, approximately 19,700 m3 C&DM would be generated. The clearance of existing buildings would mostly be carried out in the first 3 months, some of them which are not in the critical path will be cleared with 6 months.
5.4.1.3 All C&DM should be sorted on site into inert and non-inert
components. Non-inert materials (C&D waste) such as wood, glass and plastic
with not more than 30 % by weight of inert material are acceptable to EPD for
disposal to a landfill, probably WENT. However, the Waste Reduction Framework
Plan (WRFP) aims to reducing this figure to less than 20%. Inert materials
(public fill) such as soil, rubble, sand, rock, brick and concrete should be
separated and broken down to size suitable for subsequent filling. Assuming 20%
of C&DM are non-inert materials (C&D waste), the remaining 15,760 m3
inert material (public fill) will be re-used on site for filling as far as
practical. For the DBL construction, it is considered feasible to re-use most if
not all the public fill for filling the landscape embankment. Steel and other
metals should be recovered from the C&DM and recycled as far as practical if
possible.
5.4.1.4 It is considered that the handling and disposal of site clearance waste would not be a key issue and the potential environmental impact arising from handling and disposal of such waste would be negligible.
5.4.2 Surplus Cut Materials
5.4.2.1 As the quantity of cut materials as estimated in Table 5.1 would likely exceed the required fill materials within DBL project, export of cut materials would be required. However, the amount of surplus materials would be small and be around 14,000 m3. Considering the nearby project Yuen Long Highway Widening would require import of fill materials, the surplus generated in this project could be supplied to Yuen Long Highway project.
5.4.2.2 Other potential demands of fill for each year during the period works could be identified in the Fill Management Database maintained by the Marine Fill Committee (MFC). Given the changing nature of the database and the resource requirements of other concurrent projects, the sources of demand for fill at the actual time of construction will need to be established during detailed design in consultation with the PFC.
5.4.2.3 Whilst there is a variety of demand for fill, the suitability of any such fill may need to be determined for particular uses. In particular, stringent acceptability criteria are likely to be applied to any materials used in reinforced slopes and associated structures where stability is a consideration.
Table 5.1 Cut and Fill Balance
|
Section |
Items Included |
Cut Volume (m3) |
Fill Volume (m3) |
Balance (m3) |
Timing (Year) |
|
Ngau Hom Shek to Castle Peak Road |
|
16,000 |
12,000 |
-4,000 |
2003-2006 |
|
Castle Peak Road to Lam Tei Interchange |
|
80,000 |
70,000 |
-10,000 |
2003-2006 |
|
Total |
96,000 |
82,000 |
-14,000 |
||
5.4.3 Fish Pond Sediment
5.4.3.1 Only less than 0.6 ha of fish ponds are found affected. There is no need for excavation and disposal of fishpond sediment. Ground improvement works would be undertaken to speed up the consolidation process of fishpond sediment.
5.4.4 Chemical Wastes
5.4.4.1 The amount of chemical waste arising from the construction activities would be dependent on the contractor's on-site maintenance and the amount of plant and number of vehicles deployed. It is anticipated that the quantity of chemical waste, such as lubricating oil and solvent, produced from plant maintenance would be relatively small. These types of waste should be readily accepted at the Chemical Waste Treatment Facility at Tsing Yi.
5.4.4.2 Storage, handling, transport and disposal of chemical waste should be arranged in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Waste published by the EPD. Provided that this occurs, and the chemical waste is disposed of at a licensed chemical waste treatment and disposal facility, the potential environmental impacts arising from the storage, handling and disposal of a small amount of chemical waste generated from the construction activities would be negligible.
5.4.4.3 Chemical waste arisen from the project would be mainly from general construction activities. It is expected the generation of the chemical wastes would be limited. Other source of chemical waste could be from the land contamination investigation and cleanup. This would be addressed by respective remedial action plans if required.
5.4.5 General Refuse
5.4.5.1 The quantity of general refuse is associated with the number of construction workforce. It is estimated that about 200 labours would be worked on site during peak construction period in the first 24 months, thus about 0.24 tonnes (assumed 1.21kg/day/person) of commercial and industrial waste (C&I) waste would be generated per day.
5.4.5.2 Handling and disposal of general refuse should cope with the peak construction workforce during the construction period. Provided the refuse is stored and transported in accordance with good practice and disposed at licensed landfills, the potential environmental impacts would be minimal.
5.5 Proposed Mitigation Measures
5.5.0.1 This section sets out measures that should be taken to avoid or
minimise potential adverse impacts from construction waste arisings. The main
contractors should act as the overall coordinator for the management of waste
and prepare an overall Waste Management Plan (WMP) for the whole project. It is
to ensure that the recommendations and site specific factors such as the
designation of areas for the segregation and temporary storage of reusable and
recyclable materials are incorporated into the WMP. This WMP should be prepared
and submitted to the Engineer for approval.
5.5.1 Measures to be taken in Planning & Design Stages to Reduce the
Generation of C&DM
5.5.1.1 Management of C&DM has been addressed in the environmental impact assessment, ensure that the measures suggested are taken into account during the detailed design stage.
5.5.1.2 Incorporate requirements for waste management plan and proper sorting, re-use and recycling of C&DM into the construction contracts.
5.5.1.3 Provide area within construction site to allow for sorting & segregation of C&DM
5.5.2 Measures to be taken in the Construction Stage to Reduce the Generation of C&DM
General
5.5.2.1 A proper waste management plan targeting towards i) waste identification; ii) waste minimization at source; iii) waste reuse & recycle; iv) waste segregation; and v) waste disposal should be implemented to promote better waste management.
5.5.2.2 All waste materials shall be segregated into categories covering:
· Inert portion of construction & demolition material (C&DM) for
reuse on-site;
· Inert portion of C&DM to be used as public fill;
· remaining C&D waste for landfill;
· chemical waste; and
· general refuse.
5.5.2.3 On-site measures promoting proper segregation and disposal of construction waste should be implemented e.g. provide separate containers for inert (rubber, sand, stone etc) and non-inert (wood, organics etc) wastes. The inert waste should be used on site before disposed of at public filling area and the non-inert waste should be sorted for re-use or recycling before being transported to strategic landfills.
5.5.2.4 Where waste generation is unavoidable then the potential for recycling or reuse should be explored and opportunities taken. If wastes cannot be recycled then the recommended disposal routes should be followed.
5.5.2.5 Training shall be provided for workers about the concepts of the site cleanliness and appropriate waste management procedure, including waste reduction, reuse and recycling.
5.5.2.6 Regular maintenance and cleaning of the waste storage areas.
5.5.3 Measures to be taken in the Construction Stage for C&DM Disposal
General
5.5.3.1 To monitor the proper disposal of solid waste at landfills and control fly-tipping, a trip-ticket system on all solid waste transfer/disposal operations should be included as one of the contractual requirements (as described in WBTC No. 5/99) and implemented by the Environmental Team. The Independent Environmental Checker (IEC) should be responsible for auditing the result of the system. Since the amount of public fill to be generated by this project is less than 100,000 cu.m., the trip ticket system will not be required for public fill, and it will be applicable to other C&D waste.
5.5.3.2 A recording system documenting the amount of wastes generated, recycled and disposed, and the disposal methods and sites should be implemented during the construction phase by the Environmental Team and audited by the Independent Environmental Checker (IEC).
5.5.4 Waste Management Hierarchy
5.5.4.1 The various waste management options can be categorized in terms of preference from an environmental viewpoint. The preferred options have least impact and are more sustainable in the longer term. Hence, the hierarchy is as follows:
5.5.4.2 This hierarchy should be used to evaluate waste management options, thus allowing maximum waste reduction and often reducing costs. Waste reduction measures should be introduced at the design stage and carried through the construction activities, wherever possible, by careful purchasing control, reuse of formwork and good site management. By reducing or eliminating over-ordering of construction materials, waste is avoided and costs are reducing both in terms of purchasing of raw materials and in disposing of waste.
5.5.4.3 Training and instruction of construction staff should be given at the site to increase awareness and draw attention to waste management issues and the need to minimise waste generation. The training requirement should be included in the site waste management plan.
5.5.5 Storage, Collection and Transport of Waste
5.5.5.1 Permitted waste haulers should be used to collect and transport waste to the appropriate disposal points. The following measures to minimise adverse impacts should be investigated:
5.5.6 Excavated/Fill Material
5.5.6.1 The excavated material may have to be temporarily stockpiled on-site for subsequent re-use. Control measures should be taken at the stockpiling area to prevent the generation of dust and pollution of stormwater channels. Environmental control measures for dust and water pollution are covered in air and water quality sections in this report. Key control measures are highlighted below:
Dust
Water quality
5.5.7 C&D Waste
5.5.7.1 In order to minimise waste arisings and to keep environmental impacts within acceptable levels, the environmental control measures described below should be adopted.
5.5.7.2 Careful design, planning and good site management can minimise over-ordering and generation of waste materials such as concrete, mortar and cement grouts. The design of formwork should maximize the use of standard wooden panels so that high reuse levels can be achieved. Alternatives such as steel formwork or plastic facing should be considered to increase the potential for reuse.
5.5.7.3 The contractor should recycle as much of the C&DM as possible on-site. Proper segregation of waste types on site will increase the feasibility of certain components of the waste stream by recycling contractors. For example, concrete and masonry can be used as general fill and reinforcement can be taken to steel mills. Different areas of the worksite should be designated for such segregation and storage wherever site conditions permit.
5.5.7.4 The handling and disposal of bentonite slurries, if any, should be undertaken in accordance within ProPECC PN 1/94 on construction site drainage.
5.5.7.5 In the event that the public fill exceeds the capacity of the landscape embankment, the identification of additional disposal sites for fill created by the construction works should be considered during the detailed design stage of the Project.
5.5.7.6 In order to avoid dust or odour impacts, vehicles leaving a works area
carrying C&D wastes or public fill should have their load covered. Vehicles
should be routed as far as possible to avoid sensitive receivers in the area.
5.5.7.7 Some good quality reusable topsoil is expected from site clearance works across agricultural land. This can be locally stockpiled and used later in final landscaping works, thus saving on costs for such works and transportation and environmental impacts of disposal.
5.5.7.8 Construction and demolition wastes currently comprise approximately 35% of waste input to landfills. To maximize landfill life, government policy discourages the disposal of C&D wastes with more than 30% inert material (by weight) at landfills.
5.5.7.9 Effective from 1 July 1999, the Contractor must comply with the trip-ticket system for the disposal of Construction and Demolition (C&D) material (Works Bureau Technical Circular (WBTC) No. 5/99 Ref: WB(W)211/32/02). Confirmation has to be sought from the Public Fill Committee (PFC) and EPD regarding the availability of public filling facilities or a landfill, for inert C&D waste and non-inert C&D waste respectively.
5.5.7.10 Particular Specification of the Project shall include the following
clauses with the terminology defined under WBTC No. 4/98:
5.5.7.11 The Government has established a charging scheme for the disposal of waste to landfill. When it is implemented, this will provide an additional incentive to reduce the volume of waste generated and to ensure proper segregation of types of waste to allow free disposal of inert material to public filling areas.
5.5.8 Chemical Waste
5.5.8.1 For those processes which generate chemical waste, it may be possible to find alternatives which generate reduced quantities or even no chemical waste, or less dangerous types of chemical waste.
5.5.8.2 Chemical waste that is produced, as defined by Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation (CWR), should be handled in accordance with the Code of Practice on the Packaging, Handling and Storage of Chemical Wastes. The producer of chemical wastes should be registered as chemical waste producer in accordance with the CWR.
5.5.8.3 Containers used for the storage of chemical waste should:
5.5.8.4 The storage area for chemical waste should:
5.5.8.5 Disposal of chemical waste should:
5.5.8.6 The Centre for Environmental Technology operates a Waste Exchange Scheme that can assist in finding receivers or buyers for the small quantity of chemical waste to be generated from the Project.
5.5.9 General Refuse
5.5.9.1 General refuse should be stored in enclosed bins or compaction units separate from C&DM and chemical wastes. A reputable waste collector should be employed by the contractor to remove general refuse from the site, separately from C&DM and chemical wastes, on a daily or every second day basis to minimise odour, pest and litter impacts. The burning of refuse at construction sites is not permitted under the Air Pollution Control Ordinance (Cap 311).
5.5.9.2 General refuse is generated largely by food service activities on site, so reusable rather than disposable dishware should be used if feasible. Aluminum cans are often recovered from the waste stream by individual collectors if they are segregated or easily accessible, so separate labeled bins for their deposit should be provided if feasible.
5.5.9.3 Office waste can be reduced through recycling of paper if volumes are large enough to warrant collection. Participation in a local collection scheme should be considered if one is available.
5.6 Environmental Monitoring and Audit Requirements
5.6.0.1 It is recommended that auditing of each waste stream be carried out periodically to determine if waste is being managed in accordance with approved procedures and the site waste management plan. The audits should look at all aspects of waste management including waste generation, storage, recycling, treatment, transportation, and disposal. An appropriate audit programme would be to undertake a first audit at the commencement for the construction works, and then to audit quarterly thereafter.
5.7.0.1 An assessment of the potential environmental impacts of waste arising from the construction of the Project has been conducted. Operational impacts on the proposed route are expected to be minimal. Key issues include the need for effective waste management planning during the construction phase. Waste management methods and practices and other environmental control measures have been recommended to ensure that potential impacts are avoided or controlled to acceptable levels. Provided all the suggested mitigation measures such as proper handling a disposal of wastes are successfully implemented, the potential environmental impacts associated with the management of waste would be insignificant. An overall Waste Management Plan should be formulated and submitted to EPD for review and upon the satisfaction by EPD prior to construction of the Project. The recommendations of the Waste Management Plan should be fully implemented. No residual impact is expected.