9.         LIQUID AND SOLId Waste MAnagemenT ASSESSMENT


9.1       Introduction


During the construction phase, quantities of excavated materials and other wastes will be generated which will require disposal in an appropriateLiquid and solid wastes generated during construction will require to be disposed of in an appropriately and environmentally acceptableacceptably manner. This section of the EIA report involves ansummarises the assessment of the potential environmental impacts fromcaused by the wastes the generation of solid and construction wastes from generated byduring the construction of the proposed works and describesrecommends an appropriate disposal strategy.  Thestrategy to alleviate the identified potential impacts. The recommended disposal strategy is based upon the waste management principle of reducingto reduce the amount of waste requiring finalfor disposal through the development of outline plans for waste avoidance, material re-use and recycling.


Mitigation measures will be proposed to alleviate the impacts caused by the ePotential environmental impacts arising from the disposal of any eExcavated materials and residual wastes may give arise to impacts duringduring their handling, temporary stockpiling or storage on site, transportation and final disposal.  AThe key task therefore of thisthe waste management assessment is to determine the types and where possible,and, where possible, estimate theing quantities of any alln solid waste arisingss.  Moreover, in order to determinearising during the construction for determining the most appropriate methods of treatment, handling and disposal, itdisposal.  It will also be importantessential to  In particular, determininge understand the nature and composition of the wastes, in particular whether the waste materials materials are eitherare inert or contaminated for allocating the appropriate disposal route, will ensure that waste materials are handled correctly and will provide will ensure that waste materials are handled correctly and will as a the basis for identifying suitable treatment or disposal options, and there by ensuring that waste materials are handled correctly.


Wastes including both the solid and liquid wastes generated during the operational phase have also been considered withinwill also be studied in this assessment. ImpactsThe findings obtained from the impact assessment on water quality from the generation of wastewaters andwaste water and the proposed mitigation measures are have been discussed separatelyas stated in Section 4 (Water Quality) will be taken into account for assessing the Quality).impact caused by the groundwater inflow into the cable tunnel. 


9.2       Objectives


The liquid and solid waste management assessment has been carried out in accordance with the requirements of Clause 3.7.2 of the Environmental Impact Assessment (EIA) Study Brief and Annexes 7 and 15 of the Technical Memorandum on Environmental Impact Assessment Process (EIA-TM).


The overall objectives for the liquid and solid waste management assessment are summarised below:to:


(i)             to assessidentify the construction activities involved for the proposed works and determine the type, nature and where possible, estimate the volumes of waste to bedetermining the types, nature and quantities of s waste generated;

(ii)           to identify any potential environmental impacts from the generation of waste associated with thecaused by the wastes generated from the proposed works;

(iii)          to categorise waste materials where practical, i.e. suitability for re-use/recycling, disposal to public filling areas, disposal to landfill and any pre-treatment requirements (particularly pre-treatment process of the slurry generated from drilling the cable tunnel) prior to disposal;

(iv)         to recommendassess and evaluate appropriate waste management options (including potential waste minimisation on-site, re-use or recycling opportunities and off-site disposal routesoptions);

(v)           to identify siterecommend appropriate management/mitigation measures that should be may need to be implemented to minimise any potential impacts fromthe identified impacts during the generation, handling, storage;

(vi)         storage and disposal measures/routings of waste,set up appropriate routes for waste disposal, in accordance with the current legislative and administrative requirements; and

(i)        to assess handling and disposal requirements of bentonite slurries in accordance with the Practice Note For Professional Persons ProPECC PN 1/94.

(vii)        pre- treatment process of the slurry generated from boring the cable tunnel and the disposal method; and


(viii)identify the possible sites for dumping.


9.3              9.3   Nature and Type of Waste Materials


9.3.1          9.3.1   Construction Phase


Wastes which willare likely to be generated during the construction phaseof the proposed works include the following:


(i)             vegetation and demolition wasteVegetation and topsoil removed from site clearance;

(i)           excavated materials from earthworks (e.g. cuttings, regradingworks);

(i)            general construction waste (e.g. wood, scrap metal,concrete);

(i)            chemical wastes generated by general site practices (e.g. vehicle and plant maintenance/servicing);and

(i)            municipal wastes generated by siteworkers.


 It is estimated that 25,000m3 of disposal materials dominantly rock with less than 10% soil will be produced. For a typical loader which can carry 5m3 disposal materials. The spoil can be removed off site within 4 months by land access if vehicle rate is 50 vehicles per day. This will be in accordance with EPD’s Technical Circular No 1-1-92, taking into consideration subsequent revisions to the quality criteria in light of the proposed New Sediment Management Framework.

(ii)           Excavated materials;

(iii)          Construction & demolition materials;

(iv)         Chemical waste;

(v)           Slurry generated from tunnel boring; and

(vi)         Municipal wastes.


Waste GeneratedVegetation removed from Site Clearance


During the ground preparatory works, areas of tree and shrub cover will need to be cleared (refer toSite clearance will be required at the proposal tunnel portal locations in Pui O and Tai Long Wan. Approximately 0.15ha of vegetation (mainly trees and shrubs identified in Section 6, Ecology) and will require disposal.  An estimated 0.15area of approximately 0.15 Ha of vegetation willtopsoil will need to be cleared and will require disposal. Detailed information on the density and eight of vegetation cover is not available at this stage and total volumes to be generated have been broadly estimated only [not expected to exceed X m3].

Topsoil will be segregated from roots and re-use for the landscaping works for the portals to

Excavated Materialsminimise the volume of waste requiring off-site disposal. The estimated waste generated from the site clearance is approximately 450m3 by assuming that each square meter of area will have approximately 0.3m3 vegetation to be cleared.


Construction & Demolition Material


Construction & demolition material may contain a mixture of inert and non-inert material. The inert portion can be used as public fill for dumping in public filling areas whilst the non-inert portion is classified as construction & demolition (C&D) waste which will require to be disposed of at a landfill site.


Underground cable – breaking up of hard paving material for laying the underground cable is the main source of construction and demolition material. The length of underground cables is approximately 2350m in Lantau and 1350m in Cheung Chau. The trench will be 2m wide totally to accommodate the proposed three cable circuits is 2m. Assuming the thickness of the paving slab is 150mm thick typically, it is estimated that approximately 1110m3 inert construction and demolition material will be generated during the trench excavation.


Cable tunnel – construction and demolition material that will likely be generated during the tunnelling works will mainly occur in the construction of the ventilation building and the tunnel portals. The proposed ventilation building is a two storeys structure, approximately 13m long, 6m wide and 7 m high. Construction and demolition materials arising from the construction including:-


·         waste timber formwork – approximately 500m2 or equivalent to 10m3 by volume;

·         spent concrete and cement screeding – very minimal, assume 20m3 ;

·         waste reinforcement bars – very minimal, assume 3m3 waste material will be generated and collected for re-cycling; and

·         material and equipment wrappings, assume 30m3 .


The estimated total volume of construction and demolition wastes to be generated is not expected to exceed 60 m3, of which 20 m3 spent concrete and cement screeding is classified as C&D materiel which can be disposed of as public fill.


Excavated Materials


The greatest volumes of excavated materialsThe greatest volume of excavated material will arise from the excavation of the cable tunnel and at the tunnel portals.  Wherever possible,trench, cable tunnel and the site formation at the portals in Pui O and Tai Long Wan. The approach to be adopted for this material is one of “zero off-site disposal wherever possible. In this case, the excavated material from the earthworks will be re-used on- site as structural fill or for landscaping purposes.  This will - thus maximiseing the utilisation use rate of materials on site and reducing reduce the requirements for off sitewill be re-used on site for backfilling or for disposal.

forming the temporary working platform at the Pui O portal.


For excavated soils to be re-usable, materials must be clean, inert and suitable for the proposed engineering or landscaping use. A desk based review ofdesk-based review supported by site observations on the current land use along the route was undertaken in order to assess the likelihood of potential for the excavation of encountering contaminated soil materials during the construction works.  Layout plans for the alignment were has been carried out and it is unlikely that contaminated material exists.


reviewed to identify potential contaminating land uses.  The desktop study  and was supported by on site observations where possible.  The review focused on areas where significant excavation would take place, i.e. where cuttings are required.  Owing to the excavation of the cable tunnel and the tunnel portals, generation of excavated materials isanticipated.


 In the unlikely event that contaminated materials are encountered, the appropriate measures as outlined under Section 9.4.1 should befollowed.


Construction Waste Material


 Construction waste likely to be generated during the site formation works include thefollowing:

· waste wood from concrete formwork;

·spent concrete;

· waste steel rebars from concrete reinforcement activities; and

·ent wrappings.

material and equipment wrappings.Underground cables – the overall length of underground cables is 2350m and 1350m in Lantau and Cheung Chau respectively. All materials excavated from the cable trench will be re-used for backfilling the trench and thus no off-site disposal is required.


Cable tunnel portals – the formation of the tunnel portals will require excavation on the hillside to form the required works area. At the Pui O portal, approximately 800m2 hillside will be excavated and will produce approximately 2000m3 materials. This will predominantly be soil of which approximately 351100m3 excavated material will be used for forming the temporary working platform. Formation of the Tai Long Wan portal will be less extensive than the Pui O Portal. The area of hillside to be excavated is approximately 700 m2 and will produce approximately 1000m3 excavated materials. It is estimated that 80% of the excavated materials will be re-used for the slope reinstatement work upon completion of the Tai Long Wan Portals. The estimated amount of excavated materials arising from construction of the tunnel portals in Pui O and Tai Long Wan is approximately 1850100m3


Cable tunnel – the diameter of the proposed cable tunnel is 3.4m with overall length of 3000m. It is estimated that 27,000m3 will be excavated from the tunnel. Excavated materials dominantly rock with less than 10% soil content will be produced.


Submarine cables – the submarine cables will be laid by direct burying method. No excavated material is anticipated to be generated during the course of submarine cables laying works. 

The project works incorporates the construction of retaining walls, abutments and viaducts which may have piled foundations whichthat. may require the use of The contractor may utilise bentonite slurries. during pile construction and in It is common accordance with common practice among contractors, these are likely to be reuse re-usedthese slurries during the construction period, thus reducing the volume requiring final disposal. 


The estimated total volume of construction wasteand demolition wastes to be generated is not expected to exceed 5000700 m3.Volumes of bentonite slurries requiring final disposal will depend on site practices.


Chemical Waste Material


Plant and vehicle maintenanceservicing will likely be the primary source of cChemical wastes to be generated d during the construction period.  are likely to principally result from plant and vehicle maintenance and servicing. The majority of chemical waste produced is therefore expected to consist of waste lubricants and oils and solvents.  Typical wastes may include the following:


·         solid wastes (empty fuel/lubricant drums, used oil/air filters, scrap batteries, vehicle parts); and

·         liquid wastes (used lubricants, spent acid/alkali from batteries maintenance, waste oils/grease, gearbox fluids, spent mineral oils/cleaning fluids, spent solvents/detergents and possibly spent acid/alkali from batteries maintenance produced from cleaning activities).


The volume of chemical waste will depend upon site practices and the total number of plant and / site vehicles and how much maintenance is actually carried out on site.  Volumes generated are  Hhowever considered it is unlikely that volumes will to exceed 450 litres / month (provisional estimate).


Slurry generated from tunnel boring


            Chiller will be used for cooling in the boring process to avoid excessive consumption of water which leading to generation of slurry and adversely affect the water quality of the water receiving bodies. Groundwater inflow into the tunnel depends on various factors:-


·         the size of the water source;

·         the head of water above tunnel;

·         the  horizontal separation between the water source and the tunnel;

·         the recharge to the water source;

·         the degree of joint openness.


            The condition of water inflow into the cable tunnel has been investigated in the tunnel preliminary design. The tunnel designers have stated in the Preliminary Design Final Report, August 2001, that methods such as pre-injection will be adopted to avoid excessive inflow of  groundwater during construction. The method involves drilling at the faces to form probe holes for grout injection. With the implementation of the pre-injection method, the amount of water inflow into the tunnel is considered very minimal.


            However, as a preventive measure, in case of slurry generated from the boring operation as a result of groundwater seepage, the slurry will be properly collected and discharged into sedimentation tank and de-silting tanks for sedimentation and filtration prior to discharge. As indicated in Section 4 if the sedimentation tanks cannot treat waster water to the level required for discharge (as will be stated in the discharge licence).


Municipal Waste


Site construction workersWorkers will generate municipal wastes which will besuch as predominantly comprisecomposed of  food wastes, packaging andwaste paper.


wastepaper. No accurate figures are available on the likely volumes of to be generated by site workers are available although EPD have predicted that on average,For estimating the quantity of municipal wastes, EPD’s average value 1.07kg/employee/day of municipal waste may be expectedhas been adopted (Monitoring of Municipal Solid Waste 1996, EPD (1997) Hong Kong Government). The total volume of waste generated depends on the number of quantity ofworkers to be employed on site and the anticipated maximum number of workers and site staff to be employed at peak time is 50 number.  Considering 6 working days per week, the amount of municipal waste generated will thus be dependent on the number of sitebe 321 kg/week. Disposal will be the responsibility of the Contractor who shall in accordance with general avoidance of workers that the contractor proposes to use.  For estimation purposes, we have assumed a maximum of 50 site staff. nuisances measures (required under the Contract) remove material at such a frequency to avoid nuisance.


The estimated sewage arising from the workforce during the construction phase will be 3.0m3/day according to the Sewerage Manual (Part 1), Drainage Services Department, 1995. Facilities such as portaloo should be provided and no sewage is allowed to be discharged directly into receiving water. With the provision of such sanitary facilities and implementation of proper management and cleaning procedure, no adverse impact is envisaged on receiving waters. The flow and loads caused by the construction workforce and the result are presented in the following Table 9-1.


Table 9-1         Estimated Flow and Loads Caused by the Construction Workforce


Flow (m3/d)



BOD (kg/d)

COD (kg/d)

TKN (kg/d)

NH3N (kg/d)

E.Coli (no./d)










9.3.2          Operation Phase


Apart from the very minimal groundwater seepage in the cable tunnel for discharging into adjacent water receiving water bodies. It is anticipated no other waste will be generated from the operation of the Project. 


Groundwater seepage during operation phase


Although the envisaged rate of water inflow into the cable tunnel is low, drainage channels will be installed to discharge groundwater by gravity systems to the main 200mm diameter drain located in the tunnel invert. No water pumps will be required and provided inside the tunnel. Since the groundwater is unlikely to be contaminated, it is anticipated no adverse impacts will arise as a result of discharging this water to the water receiving body (marine environment).


9.3.3          9.3.2  Summary and Estimated Volumes of Generated Waste


Broad estimates for the volumes of generated waste have been assigned for each waste type although total amounts will be determined by the contractor's working practices/site procedures.  Estimated volumes of materials to be generated are presented with in Table 9-1.



The construction programme presented inwill extend over a an approximate 3 year period3 year period (March 2002 to February 2005), with site clearance, earthworks and construction activities phased according to the following construction sections of highway: 2005).  The estimated types and volumes of waste generated have been identified and are summarised in Table 9-2.


(i)Tunnel section

(i)Submarine section

(i)Underground section

(i)Testing and Commissioning for the wholeroute


 Table 9-1

Table 9-2         Summary of Wastes to be Generated




Material Type

Likely Time of Arising


Estimated Total Volumes Generated

Construction Phase – Underground cables

Breaking up of hard paving

C&D materials disposed of as public fill

Laying of underground cables 

1,100 m3


Trench excavation


Laying of underground


Construction Phase – Cable Tunnel 

Site clearance

C&D Waste mainly trees and shrubs

Formation of tunnel portals

450 m3 for a coverage area of  0.15ha



(100% surplus materials to be disposed of as public fill)

Formation of tunnel portals in Pui O and Tai Long Wan

1,850100 m3


Rock (100% to be reused for other CLP’s projects)

Tunnel construction 

27,000 m3

Construction of  ventilation building and tunnel portals

C&D materials disposed of as public fill

Construction of  ventilation building and tunnel portals

60 m3

Tunnel drilling and groundwater seepage


Tunnel construction

Very minimal

Construction Phase – Miscellaneous 

Servicing of construction plants

Chemical waste

Throughout construction period

450 litre/month

Municipal wastes

Municipal waste (general Refuse generated by site staff)

Throughout construction period

321 kg/week


Operational Phase

Seepage  of groundwater 

Ground water

Throughout the operation phase

Very minimal



9.4       Potential Impacts & Mitigation Measures


Waste materials have the potential to cause adverse environmental impacts during generation, storage, transport and disposal. The principal adverse effects relate to dust, visual impacts, water quality, and general health and safety and visual impacts.  For each anticipated waste category, the potential environmental impacts are highlighted and appropriate mitigation measures/disposal options recommended below.  These recommendations form the basis of the Waste Management Plan (WMP).


Overall, the project should aim to implementW waste management procedures should be implemented to minimise potential impacts to the environment.  This may be achieved by consideration and application of the following protocols :


(i)             avoiding and/or minimisingavoid and/or minimise waste generation where practical by improvements or changes in the project design or site procedures;wherever practical by changing its quality or site procedures (e.g. convert excavated soil to topsoil by mixing with compost, allow excavated material for backfilling in other locations simultaneously);

(ii)           reusing/recycling/recovering materialsmaximise the opportunity for reusing/recycling/recoveringmaterials where possible and thereby negating/minimisingnegate/minimise the disposal requirements (e.g. by waste segregation according to type, separation of recyclable materials such as metal, reuse of wood from site hoarding/concrete formwork,maximise reuse of timber formwork wherever possible, utilisation of excavated materials for filling or landscaping); and

(iii)          ensuringensure that all treatment and disposal options are comply with best practice and any all relevant guidelines and legislation.


The following specific measures should therefore be adopted during the detailed design and construction stages of the project to minimise waste generation:


Detailed Design :


·         Minimising excavation requirements as far as possible.

·         Balancing cut and fill requirements.

·         Evaluating the potentialEvaluate the opportunities for maximising the re-use of excavated materials for example, within landscape mounds.balancing the volume of excavation and backfilling;

·         ConsideringIdentified possible treatments for unsuitable excavated materials for re-use e.g. upgrading of subsoils to top soilssubsoil to topsoil by mixing with compost.compost; and

·         Providing anAllocate area within the construction site to allow for sorting and segregation of materials.


Construction :


·         SSegregatingegregate waste materials according to types to facilitate re-use and recycling.recycling;

·         Separation ofSeparate inert construction and demolition materials for either re-use on-site or use as public fill.dumping into public filling area or landfill site;

·         During demolition works, segregatingSegregate different materials at source as far as practical.practical;

·         CCo-ordinate material deliveries to site in order to minimise storage times on site and the likelihood of causing damage.to avoid damage and producing waste material; and

·         Consider on site mulching of vegetation to reduce bulk and review opportunities for possible use within landscapingareas.

·          TrainingProvide training to site staff in waste minimisation practices.


In accordance with good practice, accurate site recordsA comprehensive site record should be maintained throughout the construction works detailingperiod for easy tracking of details on the quantities of materials; a) generated on site; b) reused on site; and c) disposed off site, together with disposal routes/locations.  TheNo burning of wastes on-site will not be permitted.materials on-site is allowed. 


Reference should be made to the WBTC No. 5/98 “On Site Sorting of Construction Waste on Demolition Sites”, WBTC No. 5/99 “Trip-ticket System for Disposal of Construction and Demolition Material” and WBTC No. 25/99 “Incorporation of Information on Construction and Demolition Material Management”.  WBTC No. 5/98 refers to contracts which comprise solely demolition works although the measures proposed for mandatory on-site sorting of construction and demolition (C&D) material represents good site practice.  The separation of inert C&D material (suitable for public filling) from C&D waste (considered unsuitable for use as public fill) is required to minimise the volumes requiring landfill disposal as far as practical.  


WBTC No. 5/99 refers to the implementation of a trip ticket system for the proper disposal of C&D material to either public filling areas or landfills.  WBTC No. 25/99 refers to the management of construction and demolition material (C&DM), i.e. inert material suitable for use as public fill or in earth filling projects.


Full reference should be made to the relevant WBTC for further details.



9.4.1     Wastes Generated from Site Clearance and Excavated Materials


During the handling, storage, transportation and disposal of site clearance wastes and excavated materials, potential adverse effects may relate to dust, visual impacts, water and general health and safety.




All materials should be re-used orexcavated materials other than for re-use should be transported off site as soon as possible to minimise the potential for adverse environmental impacts.  It is recognised that some stockpiling of materials will be required in some instances although these should be segregated in terms of material type as far as practical. to facilitate the potential for material re-use (e.gi.e. top soilfor landscaping, suitable fill for engineering works).


 All Transportation of excavated material off site should be handled in a manner that minimisesproper manner to minimise the release of fugitive dust (especially during hot and dry weather) and where possible the movement of material should be kept to a minimum. Mitigation measures related to dust measures for thegenerated due to handling of excavated materials on-site have been addressed in detail within Section 3 (Air Quality).  Within


the stockpile area,For stockpiling, the following measures should be in place to control potential impacts :theimplemented to mitigate against the likely adverse impacts to the environment: generation of dust and contaminated surface water run-off (i.e. high suspended solids) :


·         ecoveringxcavated material should be covered to prevent washout and erosion during heavy rainfall;

·         ausingdopt dust suppression techniques (such as dampening with fine water spray and covering with tarpaulin);

·         acontrolling thevoid excessive use of water during spraying to prevent the generation of runoff contaminated with elevated levels of suspended solids;

·         segregation of the surface water system for the stockpile area and the fitting of silt traps where appropriate;provide silt traps in the surface drainage system in the stockpile area;

·         locatinglocate stockpiles to minimise potential visual impacts;

·         minimising land intake of stockpile areas as far aspossible;

·          provide fencing withinfence up the designated areas for stockpiling to separate sensitive habitats and prevent stockpiling in unsuitableinappropriate  locations; and

·         designate appropriate haulage roads.


A reduction in the total volume of excavated materials requiring off site disposal will be achieved asoff-site can be achievedas far as possible by optimising the re-use of suitable material on-site.


BothFor the surplus eExcavated material which cannot be re-used on site and inert construction and demolition materials willwhich require disposal to at public filling areas.  Theareas, two possible locations have been identified. These are  the public filling area at Tung Chung Development Phase 3A and the public fill stockpiling area at Mui Wo have beenWo. Both were identified by the Secretary, Public Filling Committee (PFC) as possibleavailable sites duringlocations available for dumping in accordance with the construction works programme. 


Cleared vegetation derived from the ground preparatory workssite clearance in the tunnel portals should be segregated from any soil materials where practical and sent to a suitable disposal site such as the WENT Landfill.  WENT Landfill will only accept restrictions specify a a maximum of 30% by weight of inert construction waste.  It is therefore important  and procedures on site should ensure only that soil / vegetation are kept segregated. Mulching of vegetation on site would also reduce the material bulk of material requiring disposal.  Moreover,  and where possible possible opportunities for the possible beneficial use of the mulch within landscaping areas either on site, or as part ofMoreover, the opportunity for re-using the excavated topsoil for  and landscaping proposed either on-site, or for other landscaping projects, should be identified by the contractor prior to selection of a landfill disposal option.


9.4.2     Inert Construction and Demolition Material


In view of the inert nature of such material, its disposal is unlikely to cause long-term environmental concern.  Stockpiling of all construction waste material prior to disposal should comply with the control measures outlined earlier in order to minimise any potential impacts related to dust, visual impact, water quality and general health and safety.


The excessive generation of inert construction and demolition material increases disposal costs and may take up valuable landfill space.  With the Iimplementation of good site management and careful , planning and design considerations should be in place to reduce, the  over-ordering of materials and waste generation of inert construction and demolition material should be minimised.  In accordance with WBTC No. 19/99 (Metallic Site Hoardings and Signboards), re-useable metal hoarding and signboards should also be utilised on site to reduce the volumes of inert construction and demolition material wood generated. 


Where possible, inert construction and demolition materials such as wood and metal should be separated out from other materials for recycling.  All recyclable material should be clearly segregated and stored in appropriate skips/containers or stockpiled.  Segregation of material will aid in the potential for re-use of material and in final disposal, if necessary.  Material recycling or re-use reduces both the requirement need for new construction materials and subsequent together with overall collection, transportation  and disposal costs.  Only when materials cannot be reused should it they be disposed of to a public filling area or, as a last resort, landfilled.  All construction and demolition material disposed at public filling sites must comply with the public dumping licensing requirements (e.g. the material should be inert and contain <5% by volume of timber).  As far as possible, materials should be sorted to minimise the requirement for off site disposal.


It will be the contractor's responsibility to ensure that inert construction and demolition material is collected by approved licensed waste collectors and that appropriate measures are taken to minimise adverse impacts such as dust generation.  The contractor must also ensure that all necessary disposal permits are obtained.


Bentonite slurries should be reused as far as possible and final residues disposed of in accordance with the Practice Note For Professional Persons ProPECC PN 1/94.  Slurries may either be disposed of at the marine disposal grounds (subject to obtaining a licence from EPD) or to the public drainage system following treatment to satisfy relevant effluent discharge standards (as set out in the WPCO Technical Memorandum on Effluent Standards).


9.4.3     Chemical Wastes


Chemical waste, as defined in the Waste Disposal (Chemical Waste) (General) Regulation, will require disposal by appropriate and approved means.  Potential hazards associated with disposal scheme to eliminate the potential hazards as a result of inappropriate handling of these materials. The potential hazards  include:


·         effects on human health (i.e. dermal and toxic effects with respect to site workers);

·         phytotoxic effects to vegetation;

·         contamination of the soil, groundwaters and surface water following spillage;

·         risk of fire or explosions; and

·         discharge of chemical wastes to sewer and potential disruption of the sewage treatment works.


Chemical wastes should be stored in a locked, fully bunded area which is impermeable to both water and the waste being stored.  The waste storage area should also be covered to prevent rainfall from accumulating within the bunded areas.  The bunded area must have a volume of either 110% of the largest container or 20% by volume of the chemical waste stored in that area.  Appropriate spill absorption material should be stored near the storage area in order to clean up any minor spill events.  The risks associated with chemical waste storage and handling can be further minimised by :


·         designation ofdesignate an appropriate, well ventilated storage area;

·         minimisation ofminimise waste production and recycling/reprocessing for certain waste liquids where appropriate (e.g. oils, solvents);

·         careful handling of waste fuel and oil residues;

·         use of appropriate and labelled (Chinese and English) storage containers;

·         locate storage of wastes remotearea away from sensitive receivers (e.g. drains, residential properties and water bodies); and

·         education of workers on the concepts ofprovide education to workers to enhance their knowledge on site cleanliness and appropriate waste management procedures.


An appropriate disposal facility is the Chemical Waste Treatment Centre (CWTC) at Tsing Yi.  If chemical wastes are to be generated, the contractor will need to register with EPD as a chemical waste producer and observe the requirements for chemical waste storage, labelling, transportation and disposal.  The contractor will also need to consider the guidance in "A Guide to Chemical Waste Control Scheme: A Guide to the Registration of Chemical Waste Producers" and the "Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes".  All chemical wastes should be collected from site by a licensed chemical waste collector.


Material that is not acceptable at the CWTC (e.gsuch as spent batteries) should be sent to a co-disposal landfill such as the SENT Landfill.


9.4.4     Municipal Waste


If not appropriately managed, municipal wastes generated by site workers have a potential to cause impacts in terms of nuisance, insects and vermin.  This may give rise to adverse environmental impacts for both site workers and site neighbours which could include:


·         odour nuisance if putrescible material is not collected on a frequentregularly basis;

·         wind-blown material causing litter problems;

·         propagate of vermin and pests inif the waste storage area if it is not well maintained and cleaned regularly; and

·         adverse visual impacts.visually unpleasant.


A temporary refuse collection facility should be set-up by the contractor and wastes should be stored in appropriate containers prior to collection and disposal.  A private waste collection firm may be commissioned by the site contractor to remove the waste regularly (daily basis), to the satisfaction of the Engineer.


9.5       Summary of Waste Management Plan (WMP)


A summary of the proposed mitigation measures and proposed disposal options are presented in Table 9-29-3 and form the Waste Management Plan for the proposed project works.


Table 9-29-3         Waste Management Plan



Control Measures


Proposed Disposal Method / Area

General Requirements

Detailed Design Stage

·         maximising the opportunity for re-use of excavated materials for example, forming the temporary working platform;

·         Provide treatments for converting unsuitable excavated materials for use in other purpose e.g. upgrading of subsoil to topsoil by mixing with compost;

·         providing an area within the construction site to allow for sorting and segregation of materials.




Construction Stage

·         minimisation of waste generation for disposal (via reduction/recycling/re-use);

·         segregating waste materials according to type to facilitate re-use and recycling;

·         separation of inert construction and demolition materials for either re-use on-site or use as public fill;

·         during demolition works, segregating materials at source as far as practical;

·         co-ordinate material deliveries to site in order to minimise storage times on site and the likelihood of causing damage;

·         training site staff in waste minimisation practices;

·         transport of wastes off site as soon as possible;

·         maintain enance aof comprehensive accurate waste records;

·         use of re-useable metal hoardings / signboards;

·         no on-site burning will be permitted;

·         follow the practice set out in WBTC No.5/99 “Trip-ticket System for Disposal of construction and Demolition Material”.



Cleared vegetation from site clearance

·         segregationion  of materials to facilitate disposal;

·         segregation of excavated topsoil from roots and re-use for the landscaping works to minimise the volume of waste requiring off-site disposal.


Re-use / landfill

Demolition waste

·         segregation of materials to facilitate disposal;

·         appropriate stockpile management;

·         follow the practice set out in WBTC No.5/98 “On site Sorting of Construction Waste on Demolition Sites”.


Public fill for inert wastes

Excavated materials

·         segregation of materials to facilitate disposal / reuse;

·         appropriate stockpile management;

·         re-use of excavated material on or off site (where possible);

·         special handling and disposal procedures in the event that contaminated materials are excavated;

·         follow the practice set out in WBTC No.5/99 “Trip-ticket System for Disposal of construction and Demolition Material”.


Re-use on site for suitable material.  Disposal to public fill areas for unsuitable materials.

Construction waste

·         segregation of materials to facilitate recycling/reuse (within designated area and in appropriate containers/stockpiles);

·         appropriate stockpile management;

·         planning and design considerations to reduce over ordering and waste generation;

·         recycling and re-use of materials where possible (e.g. metal, wood from hoardings, formwork);

·         for material which cannot be re-used/recycled, collection should be carried out by an approved waste contractor for landfill disposal;

·         follow the practice set out in WBTC No.5/98 “On site Sorting of Construction Waste on Demolition Sites”.


Public fill for inert wastes.  Disposal to landfill for materials unsuitable for public filling

Chemical waste

·         storage within locked, covered and bunded area;

·         the storage area should not be located adjacent to sensitive receivers e.g. drains;

·         minimise waste production and recycle oils/solvents where possible;

·         a spill response procedure should be in place and absorption material available for minor spillages;

·         use appropriate and labelled containers;

·         educate site workers on site cleanliness/waste management procedures;

·         if chemical wastes are to be generated, the contractor must register with EPD as a chemical waste producer;

·         collection by a licensed chemical waste collector.



Municipal waste

·         waste should be stored within a temporary refuse collection facility, in appropriate containers prior to collection and disposal;

·         regular, daily collections are required by an approved waste collector;

·         provide sanitary facilities.



Operational waste

·         wastes should be stored within a designated storage area;

·         waste such as material wrapping should be segregated into recyclable, non recyclable and putrescible wastes, where possible to facilitate disposal.;


Dependent upon material type – refer to the waste categories above.



9.6       Conclusions


The proposed cConstruction activitiesworks associated with  for the the proposed works will generate a number of waste materials.  These include:


·         vegetation and demolition wastes from site clearance and paving breaking

·         excavated materials

·         construction & demolition materials;

·         construction waste

·         chemical waste

·         slurry generated from tunnel boring 

·         municipal waste


The potential impacts of wastes arising from the construction phase of the installation of 132kV supply circuit project have been assessed.  Provided that the mitigation measures outlined above are in place, potential impacts to the environment associated with waste generated by the construction and operational phases of the project will be controlled.  Overall,With the recommended procedures/measures in place, the construction and operational  wastes generated/disposed alas part of this project, will should not lead to any significant adverse environmental impacts.


Further to this assessment, the waste management measures should be included in the contractors Environmental Pollution and Control Requirements as well as the Environmental Monitoring and Audit Manual.


The identified possible site for disposal


The following sites were identified as possible locations for disposal of excavated materials, construction and demolition waste & materials, chemical waste in conjunction with the construction programme of the proposed works:-


(i)             The public filling area at Tung Chung Development Phase 3A;

(ii)           The public fill stockpiling area at Mui Wo;

(iii)          The landfill site WENT in WWwest New Territories;

(iv)         Chemical Waste Treatment Centre (CWTC) at Tsing Yi;

(v)           Material that is not acceptable at the CWTC (such as spent batteries) can be sent to a co-disposal landfill such as the SENT Landfill.