7 WASTE MANAGEMENT
7.1 Background
7.1.1 There will be no spoil disposal or waste management issues during the operation of the project. This section, therefore, focuses on waste management during construction.
7.2.1 The existing waste management issues within the study area relate wholly to general refuse from the residential properties and users of the country park. This waste is collected and deposited at either the Mui Wo or North Lantau Refuse Transfer Stations before transfer to a licensed landfill for ultimate disposal. These facilities also handle construction and demolition waste from Lantau Island with any material suitable for public fill being deposited at the public fill stockpile area in Mui Wo. Both refuse transfer stations have spare daily capacity, with the North Lantau facility having significant capacity for further throughput.
7.3.1 The assessment of the environmental impacts from the handling, storage, collection, transportation and disposal of waste material generated by the project has been undertaken in accordance with Annex 7 and Annex 15 of the TMEIAO.
7.3.2 The waste management hierarchy has been applied in the assessment and development of mitigation measures for waste. The waste management hierarchy is a concept which shows the desirability of various waste management methods and comprises the following in order of preference:
· avoidance;
· minimisation;
· recycling/reuse;
· treatment; and
· disposal.
7.3.3 All opportunities for reducing waste generation have been assessed based upon the following factors:
· avoiding or minimising waste generation through changes in the design;
· adopting better management practices to promote segregation of waste materials;
· reuse and recycling; and
· diverting waste to public dumps or other construction sites.
7.3.4 The types and quantities of waste have been estimated and disposal options for each category of waste identified, taking into account the existing or future spare capacities of the waste disposal facilities and the environmental implications of the handling, collection and disposal of waste material.
7.4 Construction Waste Impacts
7.4.1 Waste Types
7.4.1.1 Activities during the construction phase will result in the generation of a variety of wastes which can broadly be classified into distinct categories based on their nature and the options for their disposal. These include:
· excavated materials suitable for reclamation and fill;
· construction and demolition waste some of which may be suitable for reclamation and fill. This category includes the vegetation cleared at the commencement of the works;
· chemical waste;
· general refuse; and
· sewage.
7.4.2.1 Excavated material from earthworks will include soil and rock material, the majority of which is expected to be of good usable quality. Thus, while this material is suitable for use in reclamations and thus not a waste product, the transport and off-site disposal of surplus excavated materials to public filling sites, public fill barging points or authorised public fill stockpile areas in large quantities has the potential to result in noise impacts, possible congestion due to increased traffic loadings and dust and exhaust emissions from the haul vehicles.
7.4.2.2 The selected alignment has the advantage of following the natural topography which minimises the extent of cut slopes required with advantages of reducing the habitat loss, visual impacts and the amount of excavation waste generated. In addition, the alignment has been designed to minimise the length of the viaduct and maximise the length of back-filled retaining walls on the down hill side. This allows for a better balance of cut and fill material and reduces the need for export or import of material with associated impacts from vehicle movements.
7.4.2.3 Waste quantities from the selected alignment have been estimated from an assessment of the cut and fill activities determined. The values represent a preliminary conservative estimate based upon the latest specification for cut and fill areas. In addition, it should be noted that it is not possible at this stage to predict the Contractor’s preferred methods of unitisation of excavated material. For the sections of the alignment on structure, no material will be required or will be generated and thus these sections are not included in the volumes predicted. The absolute volumes of cut and fill along the alignment are shown in Table 7.1 below.
Table 7.1 Volumes of Cut
and Fill Material
|
Alignment
Section |
Alignment
Chainage |
Amount
of Cut (m3) |
Amount
of Fill (m3) |
|
On-line section between Lung Tseng Tau and Tai Tung Shan Service
Reservoir |
1000 – 3200 |
24,360 |
2,735 |
|
Northern section between Tai Tung Shan Service Reservoir and the
crest |
3200 – 4500 |
78,125 |
22,870 |
|
Southern section between the crest and South Lantau Road (excluding
bus-bus interchange) |
4500 - 7200 |
62,370 |
32,660 |
|
Bus bay and taxi facilities |
- |
26,760 |
14,830 |
|
TOTAL |
|
191,615 |
73,095 |
7.4.2.4 The values show that a total of 191,615m3 of material will be generated by the construction of the project and 73,095m3 of material will be required for earthworks. Overall, the cut and fill values have been balanced as far as possible but an approximate 118,520m3 surplus of material predicted, based upon the assumption that all cut material can be re-used and it is anticipated that only a negligible amount of material will be unsuitable for use.
7.4.2.5 The breakdown of the surplus of excavated material within the main 4 sections of the alignment is provided in Table 7.2 below. The balance between cut and fill is best along the southern section of the alignment and at the bus bay and taxi facilities bus interchange where about 50% and 55% of the excavated material will be used as fill respectively. Along the on-line part of the alignment between Lung Tseng Tau and the service reservoir at Tai Tung Shan, while the quantities are relatively small, only 11% of the excavated material is required as fill. The largest amount of surplus is generated in the northern section between Tai Tung Shan service reservoir and the crest, with over 55, 000m3 of material requiring disposal.
Table
7.2 Estimated Surplus Excavated
Material
|
Alignment
Section |
Alignment
Chainage |
Surplus
Material Cut (m3) |
|
On-line Section between Lung Tseng Tau and Tai Tung Shan Service
Reservoir |
1000 – 3200 |
21,625 |
|
Northern section between Tai Tung Shan Service Reservoir and the
crest |
3200 – 4500 |
55,255 |
|
Southern section between the crest and South Lantau Road (excluding
bus-bus interchange) |
4500 - 7200 |
29,710 |
|
Bus bay and taxi facilities |
- |
11,930 |
7.4.2.6 It is the intention to reuse all the material on site and it is predicted that only a negligible quantity of unsuitable material (material which is waterlogged or not of a suitable grade) will have to be transported off-site to a public fill facility. The Project will maximise the use of recycled aggregates and rock products. The storage, handling and transportation of excavated material prior to utilisation on site or disposal of any unsuitable material at public fill sites could lead to the generation of dust and may be visually intrusive and waste management control will be required to prevent any impacts.
7.4.2.6 However, it is apparent that there will be an overall surplus of material. The process of reuse will be instigated as soon as initial excavations have been carried out and thus, the predicted surplus material will be generated along the length of the alignment and not in any one location. The surplus material is suitable for public fill and the closest facility for handling this type of material is the public fill stockpile in Mui Wo. This has the potential for impacts on the local residents associated with the possible dust generation from the imported fill, deposition of material on public roads and emissions and noise from the construction vehicles. Assuming an average truck capacity of 7.5m3 and assuming all material was deposited at Mui Wo, approximately 15,800 vehicle trips would be required for the removal of the surplus fill over the duration of the job. Based upon the fill being exported of a regular basis for the majority of the 36 month contract, say 27 months, this would equate to around 24 trips per day, based upon a 6 day working week. This activities would also coincide with the removal of C&D material requiring a further 2 trips per day, as detailed in Section 7.4.3 below. The impact on Mui Wo and the residents along South Lantau Road of about 4 trips per hour is not predicted to yield any significant impacts but could cause some disturbance to local residents.
7.4.2.7 However, according to the Public Fill Management Committee recent projections, the North Tsing Yi Reclamation will receive public fill from mid 2002 and early 2005 and the Development in Tung Chung and Tai Ho Phase 3 on North Lantau would be in progress between January 2005 and December 2010. These projects coincide with the Tung Chung Road improvement works programme of between 2003 and 2006 and therefore it is possible that the C&D waste suitable for public fill could be transported directly for use in these areas. A temporary C&D recycling facility is also proposed for Tuen Mun Area 38. Export via the Tung Chung end of the alignment could cause some disturbance to the residents in the villages of Lung Tseng Tau but the numbers are generally less than those which could be potentially affected along South Lantau Road and in Mui Wo. Thus, in order to reduce the disturbance on the residents of South Lantau Road and Mui Wo, it is recommended that surplus excavated material from the northern sections of the alignment be removed via the Tung Chung end of the project where possible.
7.4.2.8 Tree planting will also require the import of some high grade earth to ensure a high success rate for new tree growth and thus, an estimated additional 2,600m3 of high grade material is predicted as being required. Assuming an average truck capacity of 7.5m3, approximately 370 vehicle trips would be required for the imported soil over a 6 month period towards the end of the project. This would equate to only around 2-3 trips per day over the entire site and at a time when removal of surplus excavated material and C&D waste will have been completed, so no cumulative transportation impacts would occur. It is possible that this material may be imported via barge to Mui Wo and transferred to the road works area via the local road network or be imported via Tung Chung. In either scenario, this level of traffic is not predicted to yield any significant environmental impacts.
7.4.2.9 The Natural Terrain Hazard Assessment (NTHA) has identified that some measures to protect against landslip/rockfall from the natural terrain above the road link will be required. The work will include the stabilisation of unstable boulders. Details on the scope and extent of the proposed works are provided in Section 2 of this report. These works will not generate any significant waste, being limited to waste construction materials and packaging and small amount of excavated materials. The amounts are negligible in comparison to the project as a whole and can easily be handled, stored, transported and disposed off under the waste management systems set up for the project as a whole.
7.4.2.10 A detailed ground investigation will also be required during the design phase of the detailed project. This will comprise trial pit and boreholes along the length of the alignment, particularly at foundation locations. Trail pits will be backfilled using the material excavated from them and the cores from the boreholes will be taken away for laboratory testing. Thus, waste arisings will be negligible.
7.4.2.11 While, no significant impacts associated with waste are predicted, waste management measures to control stockpiling, temporary storage and on-site transportation requirements, which could lead to short-term dust and visual impacts, particularly in Tung Chung and Cheung Sha where the majority of the sensitive receivers are located, will be required. In addition, improper waste handling and storage could result in adverse impacts on nearby streams, the majority of which are ecologically sensitive. Mitigation measures to control any impacts from excavation waste are detailed in Section 7.5 below.
7.4.3 Construction and Demolition Waste
7.4.3.1
Construction and demolition (C&D)
material will arise from a number of site activities and may include:
· cleared vegetation;
· wood from formwork;
· road and pavement demolition waste;
· slope surfacing removed during man-made slope upgrading works including on the obsolete sections of road;
· equipment and vehicle maintenance;
· materials and equipment wrappings;
· unusable cement/grouting mixes; and
· damaged or contaminated construction materials.
7.4.3.2 If C&D materials are generated in large quantities they may hinder normal construction activities and present a safety hazard if not removed, in addition to causing potential water quality impacts. C&D materials generally comprise 20% C&D waste and 80% material suitable for public fill. However, if the public fill fraction is not separated, all the material will be disposed of at a licensed landfill facility. As the capacity of Hong Kong’s existing landfill sites rapidly reduces, it is necessary to minimise the amount of waste material being disposed of in this manner by applying the principles of the waste management hierarchy.
7.4.3.3 The volume of construction and demolition material generated by the project will be dependant on specific operating procedures and site practices and hence cannot be quantified as a whole at this stage. However, all falsework will be steel instead of wood. As steel falsework is a proprietary system, it will be reused throughout the project and subsequent projects. Specification of the use of steel will substantially reduce the amount of waste wood that the project will generate.
7.4.3.4 The formwork would likely consist of 18mm plywood and used as shuttering largely for the sections of the alignment on structure. This material would be used only once for this purpose but can be reused throughout the construction process for other activities. The amount of wood required for shuttering would be minimal and assuming the material was recycled and reused prior to disposal, the impacts of this would not be significant.
7.4.3.5 No buildings will be demolished as a result of the project. However, C&D waste will be generated as a result of the removal of road surfacing, removal of hardstanding for the site office area, widening of road bridges and culverts and slope upgrading. This type of C&D waste is inert and suitable for public fill. In addition, site clearance will generate a mixture of topsoil and vegetative matter which will form C&D waste which, not being suitable for public fill, will require disposal to landfill. Table 7.3 summarises the amounts of C&D material predicted to be generated for each of these activities.
Table 7.3 Summary of
C&D Material Arisings
|
Activity |
Amount of C&D Material (tonnes) |
|
Vegetation clearance |
4,825(1) |
|
Road pavement demolition |
17,820 |
|
Site office area pavement
demolition |
2,640 |
|
Bridge/culvert widening |
242 |
|
Slope Upgrading |
1,890 |
|
TOTAL: |
27,417 |
Note (1): Not suitable for public fill; requires
disposal at licensed landfill site.
7.4.3.6 The other types of C&D waste are expected to be limited, however, with only small quantities of maintenance and packaging waste being generated. Measures to minimise the generation of waste shall be implemented and demolition waste shall be sorted to extract the public fill fraction.
7.4.3.7 The approximate total of 27,400 tonnes of C&D material will require removal off site. The site area, including the temporary haul roads, will have to be cleared of the vegetation at the start of construction. This process will include areas of plantation trees, in accordance with the tree survey report, and the mixture of topsoil and vegetative matter will form C&D waste which, not being suitable for public fill, will require disposal to landfill. It is estimated that 4,825 tonnes of cleared vegetation will be generated. However, by stripping/uprooting the vegetation first, before removing the top soil, it would be possible separate the earth into material for reuse on site, material suitable for public fill and the fraction that would require disposal to landfill. In this way, the amount of waste can be minimised. However, there is no known currently viable opportunity in Hong Kong to reuse or recycle unseasoned trees. Thus, treatment of the vegetative material to reduce the volume of waste to be transported and disposed of would minimise any impacts.
7.4.3.8 The 4,825 tonnes of vegetation equates to a volume of 5,300m3 of C&D material which is not suitable for public fill and thus, this will be to transported separately to the landfill via the Mui Wo or North Lantau refuse transfer stations. Transportation of this material will require about 706 loads (based upon a truck size of 7.5m3) but pre chopping and compacting of the material using a mobile compactor will help to reduce to reduce the volume of material to be disposed of. Clearance of vegetation will take place within the first 3 months of the project and thus, its removal would require about 10 trucks per day. This rate of delivery equates to in the region of 23 tonnes of material per day which is well within the capacity of both the Mui Wo refuse transfer station and North Lantau refuse transfer station which can accept 145 and 900 tonnes per day respectively.
7.4.3.9 The remaining 22,500 tonnes or 13,000m3 of C&D waste generated will be suitable for public fill. The bulk of this material is generated by the removal of the road pavement. This activity will be on going throughout the majority of the project duration, over about a 27 month period. The total number of trips required for the removal of this material would be in the region of 1733, which would equate to about 2 trips per day based upon the regular disposal of the material of the active works period. This material could be transferred to the public fill stockpile in Mui Wo. Alternatively, according to the Public Fill Management Committee recent projections, the North Tsing Yi Reclamation will receive public fill from mid 2002 and early 2005 and the Development in Tung Chung and Tai Ho Phase 3 would be in progress between January 2005 and December 2010. These projects coincide with the Tung Chung Road improvement works programme of between 2003 and 2006 and therefore it is possible that the C&D waste suitable for public fill could be transported directly for use in these areas. In either scenario, the trip rate is sufficiently low as to not give rise to significant impacts on local residents. However, as removal of C&D waste will be on-going at the same time as removal of excavated material, it is recommended that material generated in the northern section of the alignment be removed via Tung Chung to minimise disturbance to residents along South Lantau Road and in Mui Wo.
7.4.4.1 Chemical wastes likely to be generated during the construction will, for the most part, arise from the maintenance of plant and equipment. These may include the following:
¨ spent filter cartridges containing heavy metals;
¨ scrap batteries or spent acid/alkali from their maintenance;
¨ brake clutch linings containing asbestos materials;
¨ used hydraulic and lubricating oil;
¨ spent mineral oils/cleaning fluids from mechanical machinery;
¨ spent solvents/solutions, which may be halogenated, from equipment cleaning; and
¨ paints and paint containers.
7.4.4.2 Chemical wastes can pose environmental and health and safety hazards if not stored and disposed of in an appropriate manner. However, it is unlikely that any large quantities of chemical wastes will be generated during the construction of this project and if handled, stored, transported and disposed of in an appropriate manner, no impacts are predicted. Notwithstanding, no chemical waste shall be stored within the water gathering grounds and all maintenance activities which could give rise to the materials listed above, shall be undertaken outside the water gathering grounds.
7.4.5.1 The construction works will result in the generation of a variety of general refuse requiring disposal. These wastes will arise mainly at the major work site located in Lung Tseng Tau and Cheung Sha. General refuse may include office waste, newspapers, food wastes from canteen and packaging waste and will generally be disposed of at landfill.
7.4.5.2 The storage of general refuse has the potential to give rise to a variety of adverse environmental impacts. These include odour if waste is not collected frequently (eg. daily), windblown litter, water quality impacts if waste enters water bodies, and visual impact. The site may also attract pests and vermin if the waste storage area is not well maintained and cleaned regularly. In addition, disposal of wastes at sites other than approved landfills, can also lead to similar adverse impacts at those sites. However, with suitable methods to control the storage, transfer and disposal of this material, no impacts are predicted. Notwithstanding, no canteen facilities will be located within the water gathering grounds.
7.4.6.1 The construction workforce will produce sewage which requires proper disposal. Along the alignment where there are no foul sewers, chemical toilets shall be provided. In order to avoid unacceptable odour problems and to safeguard the health of the workers, nightsoil will need to be removed and disposed off site frequently. Also, sewage from the site offices will require to be properly collected and disposed of. It is not anticipated that the site offices in Tung Chung and Cheung Sha will be able to be connected to the local sewerage system. Therefore, these sites will require the use of an on-site chemical treatment facility, which will require emptying by tanker and a licensed contractor on a regular basis.
7.5 Waste Management
Mitigation Measures
7.5.1 Mitigation measures are required to ensure the proper handling, storage, transportation and disposal of waste is carried out. Also measures to ensure that the generation of waste is avoided and minimised and that waste materials are recycled and treated as far as practicable.
7.5.2 The recommended mitigation measures for all categories of waste are as follows:
(i) the Contractor shall identify a coordinator for the management of waste. The coordinator shall prepare and implement a Waste Management Plan which specifies procedures such as a ticketing system, to facilitate tracking of loads and to ensure that illegal disposal of wastes does not occur, and protocols for the maintenance of records of the quantities of wastes generated, recycled and disposed. The Waste Management Plan shall be prepared with reference to Works Branch Technical Circular (WBTC) No. 29/2000 “Waste Management Plan” and WBTC 5/99 for the Trip-ticket System for Disposal of Construction and Demolition Material and issued to Engineer for approval and CED. CED should be contacted to confirm the availability for C&D and public fill waste;
(ii) training should be provided to workers about the concepts of site cleanliness and appropriate waste management procedure, including waste reduction, reuse and recycling;
(iii) all material shall be reused on site as far as practicable, including formwork plywood, topsoil and excavated material;
(iv) good site practice shall be implemented to avoid waste generation and promote waste minimisation;
(v) any surplus material generated shall be sorted on site into construction and demolition (C&D) waste and the public fill fraction. A sorting facility shall be set up on the site, unless a conveniently located Government facility is available. The C&D waste shall be disposed of at a licenced landfill or deposited at an authorised waste transfer facility and the material suitable for public fill delivered to a public filling area, public filling barging point or public fill stockpile area after obtaining the appropriate licence. Suitable provisions shall be included in the construction contract to ensure that the Contractor sorts and recycles waste;
(vi) trees and vegetation shall be stripped prior to site clearance, chopped and compacted using a mobile compactor to reduce the volume of material to be transported and disposed of;
(vii) the surplus excavated material from the northern sections of the alignment shall be exported via the Tung Chung end of the works area and all other material will be exported from site to the stockpile in Mui Wo, subject to consultation with the Public Fill Committee prior to construction;
(viii) excavated material shall be reused as close to the point of excavation and as soon after excavation as possible and directly transferred to the area of deposition, if practicable;
(ix) stockpiled material shall avoid vegetated areas and be covered by tarpaulins and/or watered as appropriate to prevent windblown dust and/or surface run-off. Storage of material on site shall be kept to a minimum to avoid nuisance to local residents;
(x) major stockpiled areas shall be sited outside of the country parks area and away from stream courses;
(xi)
stockpiled materials shall be
contained in a designated area down gradient from any stream, as far as
possible, or up gradient with a suitably constructed barrier to reduce loss of
materials to the stream;
(xii) excavated material in trucks shall be covered by tarpaulins to reduce the potential for spillage and dust generation;
(xiii) wheel washing facilities shall be used by all trucks entering and leaving the site to prevent transfer of mud;
(xiv) the Contractor shall register with EPD as a chemical waste producer under the Waste Disposal (Chemical Waste) (General) Regulation. A licensed contractor shall be employed to collect chemical waste for delivery to a licensed treatment facility. Suitable chemical waste storage areas shall be formed on the site for temporary storage pending collection. All chemical wastes shall be handled, stored, transported and disposed of in accordance with the Code of Practice on the Package, Labelling and Storage of Chemical Wastes and A Guide to the Chemical Waste Control Scheme published by EPD;
(xv) no fuel/oil shall be stored within the Country Park or water gathering grounds;
(xvi) no chemical wastes shall be stored in the water gathering grounds;
(xvii) no maintenance activities which may generate chemical wastes shall be undertaken in the water gathering grounds;
(xviii) no canteen facilities shall be located within the water gathering grounds;
(xix) the Contractor shall comply with WSD’s General Conditions for Working within Water Gathering Grounds;
(xx) temporary storage areas for general refuse shall be enclosed to avoid environmental impacts. Sufficient dustbins shall be provided for storage of waste as required under the Public Cleansing and Prevention of Nuisances Ordinance (Regional Council) By-laws. In addition, general refuse shall be cleared daily and shall be disposed of to the nearest licensed landfill or refuse transfer station; and
(xxi) nightsoil arising from chemical toilets shall be transported by a licensed contractor to a Government Sewage Treatment Works for disposal in accordance with the Sanitation and Conservancy (Regional Council) By-laws.
7.6 Waste Disposal Recommendations
7.6.1
Based upon the estimated quantities
and types of waste to be generated by the project, disposal options have been
determined, as detailed in Table 7.4 below.
In terms of C&D waste and general refuse, both the Mui Wo and North
Lantau refuse transfer stations have been recommended. As the project extends across the breadth of
Lantau Island, it would be preferable to remove the waste to the closest
facility. The Mui Wo facility, however,
is a relatively small operation with a 145 tonne per day permitted throughput,
of which approximately half is currently spare capacity which may not be
sufficient to take all the waste. The North Lantau facility in comparison has
substantial spare capacity in its 900 tonne per day permitted throughput and
thus is it recommended that this facility be used whenever practicable.
7.6.2 In terms of the waste suitable for public fill, the public fill stockpile in Mui Wo is a possibility. However, the North Tsing Yi Reclamation and Development in Tung Chung and Tai Ho Phase 3 will be accepting public fill between mid 2002 and end 2005 and beginning 2005 and end 2010 respectively, creating the potential for direct disposal at these sites.
Table 7.4 Recommended Waste Disposal Sites
|
Type
of Waste |
Disposal
Site |
|
Inert material (dirt/soil, concrete, bricks, masonry, ceramics,
tiles, etc.) which comply with the requirements of the Public Dumping Licence |
¨ CED public fill stockpile in Mui Wo; or
¨ North Tsing Yi Reclamation/ Development in Tung Chung and Tai Ho
Phase 3.
|
|
(1)C&D waste (plastics, glass, wood, including cleared vegetation
etc.) |
¨ North Lantau refuse transfer station
¨ Mui Wo refuse transfer station
|
|
Chemical waste (as defined under Schedule 1 of the Waste Disposal
(Chemical Waste) Regulation) |
¨ Chemical waste treatment facility at Tsing Yi; or
¨ other approved facility.
|
|
General refuse |
¨ North Lantau refuse transfer station
¨ Mui Wo refuse transfer station
|
Note (1):
All efforts to reuse and recycle C&D material should be made prior
to disposal.
7.7.1 Assuming all the mitigation measures are implemented, no residual adverse impacts from the handling, storage, transportation or disposal of the waste generated by the project are predicted.
7.8 Environmental Monitoring and Audit
7.8.1 The assessment has concluded that the handling, transportation and disposal of waste materials during construction will not give rise to significant impacts if appropriate mitigation measures are implemented. However, it is recommended that during construction phase, regular site inspections and supervision of the waste management procedures shall be undertaken as part of the EM&A procedures, to ensure proper control, all waste is removed from site areas as appropriate and illegal disposal of waste is not being undertaken. Waste EM&A during the operational stage is not required. Further details of the specific construction phase EM&A requirements are detailed in Section 13 of this report and in the EM&A Manual.