6. WASTE MANAGEMENT IMPLICATIONS

6.1 Introduction

6.1.1.1 This section discusses the waste management implications and management required as a result of the construction and operation of the Project. Impacts on water quality from wastewater and sewage generated during construction activities are discussed in Section 5, Water Quality Impact Assessment.

6.2 Environmental Legislation, Policies, Plans, Standards and Criteria

6.2.1 Legislation

6.2.1.1 The legislation on handling, treatment and disposal of wastes, which are of relevance to this Project, are:
· Waste Disposal Ordinance (Cap. 354) & relevant regulations;
· Environmental Impact Assessment Ordinance (Cap. 499); and
· Public Health and Municipal Services Ordinance (Cap. 132).

6.2.1.2 The Waste Disposal Ordinance (WDO) enacted in 1980 provides the statutory framework for the management of all wastes from where they arise to the point of final disposal i.e. control on the collection, treatment and disposal of waste. The WDO prohibits any person from using any land or premises for the disposal of wastes unless the person has been authorised by or has obtained a license from the waste disposal authority. The ordinance was amended in early 1995 to enable permit control on import and export of wastes in line with the requirements under the Basel Convention, and was in place in September 1996. The ordinance was further amended in early 1997 to enable more effective implementation of waste disposal charging.

6.2.1.3 There are a number of provisions under the WDO for dealing with certain types of waste. These include the Waste Disposal (Chemical Waste) (General) Regulation. This Cradle-to-grave control of chemical wastes was implemented in May 1993 to control all aspects of chemical waste disposal, including packaging, labelling, storage, collection, transport, treatment and final disposal. Under the Waste Disposal (Chemical Waste) (General) Regulation, any person who produces or causes to produce chemical waste must register with the Environmental Protection Department (EPD). Each registered producer has the obligation to inform the EPD as soon as practicable of any change in the particulars of the registration. The Waste Disposal (Chemical Waste) (General) Regulation requires waste producers to arrange for proper disposal of their wastes at licensed facilities and to engage a licensed collector to remove and transport the waste. It also requires that all chemical waste must be properly stored, packaged and labelled.

6.2.1.4 The Environmental Impact Assessment Ordinance (EIAO) came into operation in April 1998. Designated projects specified under Schedule 2 of the EIAO must follow the statutory EIA process and apply for environmental permits for their construction and operation. Annex 7 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) under the EIAO specifies the assessment criteria for evaluating waste management implications.

6.2.1.5 Public Health and Municipal Services Ordinance provides for the control of the discharge of hazardous materials to sewers, and for the control of littering. It also places restrictions on the storage of wastes in buildings. This may be applicable to construction site offices.

6.2.2 Other Waste Handling & Disposal Guidelines

6.2.2.1 A Waste Reduction Framework Plan (WRFP) was launched in November 1998. The WRFP sets out programme to avoid and minimise waste; promote recovery, recycling and reuse of materials; prolong the life of existing landfills and reduce the increasing costs of waste transportation, treatment and disposal. The WRFP also contains suggestions on how different sectors can incorporate various waste reduction measures into their business practices.

6.2.2.2 The Works Bureau Technical Circular No. 2/93 - Public Dumps outlines the policy relating to dumping of construction and demolition (C&D) waste. The circular states the C&D material suitable for use as fill material should not be disposed of to landfills, but should be reused in public filling area or reclamation and land formation projects. The Public Filling Sub-Committee together with Project Departments are responsible for considering the suitability of a site as a public filling area. In order to dispose of the inert portion of C&D material in a public filling area, a license issued by the Civil Engineering Department is required.

6.2.2.3 The Works Bureau Technical Circular No. 2/93B - Public Filling Facilities promulgates the revised "Dumping Licence" to supercede that promulgated under WBTC No. 2/93A with effect from 1 January 2000. Three new conditions related to the issues of illegal dumping, proper cover for the material being carried in the lorry and over-loading were added in the conditions stated on the revised "Dumping Licence".

6.2.2.4 The Works Bureau Technical Circular No. 16/96 - Wet Soil in Public Dumps promulgates the inclusion of a model particular specification clause for "Acceptance of Wet Soil" in all Contracts that involve public dumping. This circular aims at minimising the delivery of wet soil to landfills for disposal, as well as avoiding the disputes on material acceptably by the public dumps between the public dump site staff and dump truck drivers.

6.2.2.5 The Works Bureau Technical Circular No. 5/98 - On Site Sorting of Construction Waste on Demolition Sites outlines the requirement of demolitions works for on-site sorting of all C&D material prior to disposal. This circular states a particular specification clause to be included in the tender documents for mandatory on-site sorting, processing and disposal of the same.

6.2.2.6 The Works Bureau Technical Circular No. 25/99 - Incorporation of Information on Construction and Demolition Material Management in Public Works Subcommittee Papers, together with WBTC 25/99A and 25/99C, promulgates the policy and guidelines for incorporating information on the management of construction and demolition material in Publics Works Subcommittee (PWSC) papers recommending the upgrading of projects to Category A of the Public Works Programme for the implementation of construction works.

6.2.2.7 The Works Bureau Technical Circular No. 12/2000 - Fill Management aims at defining the terms of reference and membership composition of the Marine Fill Committee (MFC) and Public Fill Committee (PFC), where the functions and responsibilities of the previously established Fill Management Committee have been replaced by the MFC and PFC. This technical circular also explains how fill resources, construction and demolition material (C&DM) and dredged/excavated sediment disposal are managed.

6.2.2.8 The Works Bureau Technical Circular No. 29/2000 - Waste Management Plan introduces the requirement for contractors to prepare and implement a waste management plan (WMP). The requirement shall be included in all PWP contracts (including design and build contracts but excluding term contracts and contracts administered by Electrical and Mechanical Services Department).

6.2.2.9 The Works Bureau Technical Circular No. 12/2002 - Specifications Facilitating the Use of Recycled Aggregates promulgated the particular specifications to facilitate the use of recycled aggregates in construction works.

6.2.2.10 The Works Bureau Technical Circular No. 21/2002 - Trip-ticket System for Disposal of Construction and Demolition Material promulgates the policy to implement a trip-ticket system in Public Works Programme (PWP) contracts for the proper disposal of C&D material at public filling facilities or landfills.

6.2.2.11 The Environment, Transport and Works Bureau Technical Circular (Works) No. 33/2002 - Management of Construction and Demolition Material Including Rock introduces measures to enhance the management of C&D material including rock in public works projects.

6.3 Assessment Methodology

6.3.1.1 The assessment on waste management implications follows the criteria and guidelines as stated in Annexes 7 and 15 of the EIAO-TM together with other relevant legislation, policies, and guidelines discussed in Section 6.2 above.
6.3.1.2 This assessment covers the analysis of activities and waste generation and proposal for waste management in the construction and operational stages of the proposed project.

6.4 Construction Waste Assessment

6.4.1 General Site Wastes

6.4.1.1 Materials and equipment used on site will produce packaging and container wastes. Mitigation measures should include provision of a collection area where waste can be stored and loaded prior to removal from the site. The volume of general site wastes generated will be dependent on the Contractor's operating procedure and practices and cannot be quantified. With the implementation of the recommended mitigation measures in Section 6.6 (including good site practices), the potential environmental impacts resulting from the storage, handling and transportation of general site wastes are expected to be minimal.

6.4.2 Workforce Wastes

6.4.2.1 Throughout construction, the workforce will generate general refuse, comprising food scraps, paper, empty containers etc. Rapid and effective collection of site wastes will be required to prevent waste materials being blown around by wind, flushed or leached into the environment, and odour nuisance. The amount of general refuse which is likely to arise cannot be quantified at this time as it will be largely dependent on the size of the workforce employed by the contractor. Though with the implementation of waste management practices at the site (as recommended in Section 6.6), adverse environmental impacts are not expected to arise from the storage, handling and transportation of workforce wastes.

6.4.3 Maintenance and Chemical Wastes

6.4.3.1 Construction plant and equipment will require regular maintenance and servicing which will generate waste. Substances generated are likely to include some chemical wastes such as cleaning fluids, solvents, lubrication oil and fuel. Vehicle and equipment maintenance activities will also involve the use of a variety of chemicals, oil and lubricants, including heavy duty cleaners, organic solvents, degreasers, brake fluids, battery acid and soldering fluids. The cumulative effect of a potentially large number of small spillage during maintenance operations by faulty equipment, accidents, carelessness and deliberate discharge to drain may be significant.

6.4.3.2 Chemical wastes arising during the construction phase may pose serious environmental, health and safety hazards if not stored and disposed of in an appropriate manner as outlined in the Waste Disposal (Chemical Waste) (General) Regulation. These hazards include:

· toxic effects to workers;
· adverse impacts from spills on nearby water bodies; and
· fire hazards.

6.4.3.3 Materials classified as chemical wastes will need special handling and storage arrangements before removal for appropriate treatment at the chemical waste treatment facility (CWTF) at Tsing Yi. Wherever possible opportunities should be taken to reuse and recycle materials. Mitigation and control requirements for chemical wastes are detailed in Section 6.6. Provided that the handling, storage and disposal of chemical wastes are in accordance with these requirements, adverse environmental impacts should not result.

6.4.4 Construction and Demolition (C&D) Material

6.4.4.1 The construction activities including the site formation and foundation works at the proposed expanded and upgraded San Wai Sewage Treatment Works and the expanded Ha Tsuen Pumping Station will generate construction and demolition (C&D) material. The construction of the proposed emergency bypass culvert will be carried out by traditional open trench method and will also results in a certain amount of C&D material. An initial estimate of the total volume of excavated material likely to be generated from the construction works is given in Table 6.1.

Table 6.1   Types and Quantities of Construction Waste

Surplus C&D Material

6.4.4.2 From the breakdown given in Table 6.1 above, 17,300m3 out of the 46,400m3 of surplus excavated spoil will come from the San Wai STW upgrading and expansion site. At present, a portion of the said site is fishponds, while the remainder is being used as container storage yards. From the site investigation data, the site is covered by a layer of soft clayey materials. In order to provide a firm foundation for the ducts, cables and large diameter pipes within the sewage treatment works, it is necessary to replace these soft clayey materials with suitable filling materials. The soft materials will be used in the landscaping works of the sewage treatment works where possible and the suitability of the excavated spoil for landscaping will be subject to some soil testings.

6.4.4.3 The expansion site of San Wai STW includes an existing container yard of approximately 17,000m2 with potential localised land contamination hot spots resulted from vehicle and plant maintenance and repairing activities. Access to the container yard is currently not available. Assuming that the maintenance areas occupies not more than 5% of the container yard and 10% of those maintenance areas are subject to land contamination and require disposal of about 3m deep of contaminated soil, the total volume of contaminated soil that might require landfill disposal is estimated to be about 255m3. The exact quantity of contaminated soil will be subject to the detailed land contamination investigation to be undertaken prior to the construction of the project.

6.4.4.4 Regarding the surplus materials from the Ha Tsuen Pumping Station (15,600m3), they will be reused for the earthfilling works at San Wai STW as far as practicable. However, the possibility of reusing the surplus materials will depend on the construction programme of San Wai STW. As the project proponent has to resume the land for the expansion and upgrading of San Wai STW, the construction programme may be delayed due to public objection and other unforeseen reasons.

6.4.4.5 In constructing the emergency bypass culvert, the excavated material will be reused for backfilling the culvert. However, there will be some surplus materials that required disposal off site. Depending on the construction programme of San Wai STW, the project proponent will try her best to make use of these C&D materials for forming the San Wai STW site.

6.4.4.6 In summary, the reuse of the surplus materials from Ha Tsuen Pumping Station and the emergency bypass culvert for the earthfilling works at San Wai STW is highly dependent on the construction programme of San Wai STW, which may be affected by the land resumption procedures, public objections or other unforeseen factors.

Reuse / Recycle of C&D Material

6.4.4.7 The project proponent will try every endeavours in minimising the generation and maximise the recycle/reuse of the C&D materials. The measures that will be taken are as follows:

Ø Use the excavated materials for earthfilling as far as possible;
Ø Use the excavated soft materials for landscaping works;
Ø Reuse the C&D materials for as pipe bedding; and
Ø Use precast units to minimise the amount of C&D materials generated on site.

6.4.4.8 If the above cannot be accomplished due to various reasons beyond the project proponent's control, the surplus C&D materials will be disposed of to landfill as the last resort. No potential hazard is associated with handling and disposal of excavated spoil. The excavated spoil will be tipped to spoil banks within the construction site temporarily before removal to disposal sites.

C&D Waste Disposal Off Site

6.4.4.9 On completion of the construction works, site buildings and facilities will be demolished and removed from site. Demobilisation of infrastructure and site clearance will generate C&D material and scrap material residues which will require disposal. Certain elements may need to be disposed to landfill or public filling facilities. However, recyclable materials should be salvaged for reuse (such as wood and metal) and inert waste utilised as public fill.

6.4.4.10 The total new development construction area estimated for this project is about 45,000m2, assuming 0.05m3 of C&D waste is generated from 1m2 of area to be developed, a total of 2,250m3 of C&D waste is estimated to be generated and would require disposal at landfill sites.

6.4.4.11 The Contractor should be responsible for ensuring that waste 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 waste disposal permits are obtained. To control the proper disposal of construction and demolition material, the implementation of the trip-ticket system stipulated in WBTCs No. 21/2002 should be required.

Import Fill Material

6.4.4.12 A breakdown of the import fill material given in Table 6.1 is shown in Table 6.2 below.

Table 6.2  Breakdown of Import Fill Material

6.5 Operational Waste Assessment

6.5.1 Sludge

6.5.1.1 Sludge will be generated from the chemically enhanced primary treatment (CEPT) process proposed in the expanded and upgraded San Wai STW. Based on the findings of the SSDS Stage 1 Dosing and Disinfection Study, it is estimated that the sludge production rate would be about 200 kg dry solids per 1000m3 sewage for about 75% suspended solids removal required for the San Wai STW sewage. Therefore, with the design capacity of 246,000 m3/d for the expanded San Wai STW, the maximum daily sludge production from the expanded San Wai STW would be about 49,200 kg dry solids.
6.5.1.2 All the sludge will be dewatered onsite to more than 30% dry solids content before transporting to the designated landfill site for disposal and will be stored in covered container along the transporting route to avoid the possible odour impact on nearby sensitive receivers.

6.5.2 Spent UV Disinfection Lamps

6.5.2.1 At the UV disinfection facility, small quantities of spent or defective UV lamps may be produced from time to time. UV lamps may contain mercury and other heavy metals, and some older models may also contain polychlorinated biphenyls (PCBs). Heavy metal and PCB wastes are classified as chemical waste under Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation.

6.5.2.2 Two categories of UV systems are available in the market namely low pressure high intensity (LPHI) system and medium pressure high intensity (MPHI) system. With reference to the information provided by a number of suppliers, it is estimated that the annual consumption of UV lamps for the expanded San Wai STW would be in the range of 700 to 2000 for LPHI system and about 400 for MPHI system. Although the annual UV lamp consumption for MPHI is lower compared with the LPHI system, the power consumption of MPHI system is in general higher than LPHI system by 30% to 65% depends on the brand of the UV lamps.

6.5.2.3 Since virtually an entire fluorescent lamp can be recycled, including end caps, glass tube, wire, mercury, and phosphorus powder, recycling of spent UV lamps should be encouraged if the number of lamps warrants this practice. The recycled glass can be used as feedstock in the manufacture of glass products. The metallic portion can be used as scrap metal. Mercury can be reused in thermometers and electronic devices after further purification. However, there are currently no recyclable material collectors in Hong Kong that would handle recycling of fluorescent lamps.

6.5.2.4 If recycling facilities are not available and spent lamps must be disposed of as waste, special procedures would have to be followed. According to the Code of Practice on the Handling, Transportation and Disposal of Polychlorinated Biphenyl (PCB) Waste, "…small PCB capacitors have been used in the starter units of fluorescent lights and …typically they contain about 50 g of the lower chlorinated PCBs mostly absorbed in the windings. They normally carry no label identifying the PCB content, and they are usually disposed of as part of the redundant appliances at landfill sites. No special precautions need to be taken in the disposal of small capacitors unless the landfill operator advises that there is undue concentration at the landfill site. However, if sufficient quantities are located, they should be handled in the same manner as the larger electrical capacitors but need not be packaged as carefully because they contain no free fluids. It is understood that non-PCB materials are gaining wider use in capacitors for fluorescent light fittings, …". Therefore, the operators of the future UV disinfection facility should identify the contents of the UV lamp and confirm with EPD whether the UV lamps should be disposed of as chemical waste. If so, the handling and disposal should follow the guidelines under the Waste Disposal (Chemical Waste) (General) Regulation. In handling UV lamps, it is recommended that caution be exercised to avoid breakage and contaminant release.

6.5.3 Deodorization Secondary Wastes

6.5.3.1 Depending on the technology to be used for the proposed deodorization unit at the expanded and upgraded San Wai STW and Ha Tsuen PS, different kind of waste streams may be produced from the deodorization process. The two likely technologies would be adsorption of odorous chemicals by granulated activated carbon (GAC) and scrubbing of odorous air stream with chemical oxidants in a chemical scrubber. For example, chemicals such as sodium hydroxide, chlorine solution, and sodium hypochlorite etc are commonly used in scrubbers to oxidise odorous chemicals such as hydrogen sulphide and mercaptans.

6.5.3.2 If adsorption by GAC were adopted, exhausted GAC would normally be produced once or twice a year that requires proper disposal. If chemical scrubber is used, the spent scrubbing fluids may contain undesirable chemicals or extreme pH, which may be classified as chemical waste under Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation, depending on the concentrations of the fluid. The quantities of either the spent GAC or the scrubbing fluid to be produced would depend on the design of the deodorization unit, the throughput of the odorous gas, and the quality of the GAC or scrubbing fluids.

6.5.3.3 It is technically feasible to regenerate and reuse spent GAC but there is currently no such centralised service available in Hong Kong. However, the operator of the deodorization unit is encouraged to look into the regeneration and reuse of GAC on-site. For the purpose of this project, GAC (including caustic-impregnated GAC) would be used to remove odorous compounds from sewage sources namely hydrogen sulphide. With reference to the typical breakthrough capacity of GAC, the weight percentage of hydrogen sulphide in spent GAC would be in the range of about 3 to 7%. Spent GAC itself is not considered harmful and is known to have been safely co-disposed with other municipal solid waste at landfills. Having said that, there may be undesirable chemicals adsorbed on the carbon that cause health and environmental concerns if being disposed at landfills without any control. The operator of the deodorization unit should therefore preferably handle, store and dispose the spent GAC as chemical waste.

6.5.3.4 The spent scrubbing fluids from the chemical scrubber are likely to be categorised as chemical waste due to their characteristics as strong alkalis and oxidants. The handling, storage and disposal of the spent scrubbing fluids should follow the requirements under the Waste Disposal (Chemical Waste) (General) Regulation. Unless the spent fluids are treated to meet discharge standards as stipulated in the Technical Memorandum under Water Pollution Control Ordinance, direct discharge into local sewerage systems should not be allowed.

6.5.4 Other Operational Wastes

6.5.4.1 Small amounts of domestic waste may be generated from site management offices, and of chemical waste from equipment maintenance. Improper storage of domestic waste onsite can give rise to adverse environmental impact such as odour nuisance, vermin and pests, water quality impacts, and adverse visual impacts. If proper handling and disposal measures, as mentioned in the Section 6.6, are undertaken, no adverse impact is envisaged.

6.6 Mitigation of Adverse Impacts

6.6.1 Waste Management Plan

6.6.1.1 A proper Waste Management Plan (WMP) for the construction of the project should be submitted to the Engineer for approval and implemented. Where waste generation is unavoidable then the potential for recycling or reuse should be explored and opportunities taken. If wastes cannot be recycled, recommendations for appropriate disposal routes should be provided in the WMP. A method statement for stockpiling and transportation of the excavated material and other construction wastes should also be included in the WMP and approved before the commencement of construction. All mitigation measures arising from the approved WMP shall be fully implemented.

6.6.1.2 For the purpose of enhancing the management of C&D material including rock, and to minimize its generation at source, a C&D Material Management Plan (C&DMMP) has been prepared for this project and would be processed in accordance with the Environment, Transport and Works Bureau Technical Circular (Works) No. 33/2002 - Management of Construction and Demolition Material Including Rock. The C&DMMP is included in Appendix 6A of this report.

6.6.2 Waste Reduction Measures

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

Planning and Design Stage

· The project proponent will try every endeavours in minimising the generation and maximise the recycle/reuse of the C&D materials. The measures that will be taken are as follows:

Ø Use the excavated materials for earthfilling as far as possible;
Ø Use the excavated soft materials for landscaping works;
Ø Reuse the C&D materials for as pipe bedding; and
Ø Use precast units to minimise the amount of C&D materials generated on site.

Construction Stage

· Segregation and storage of different types of waste in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal;
· To encourage collection of aluminium cans by individual collectors, separate labelled bins should be provided to segregate this waste from other general refuse generated by the workforce;
· Any unused chemicals or those with remaining functional capacity should be recycled;
· Prior to disposal of C&D waste, it is recommended that wood, steel and other metals be separated for re-use and/or recycling and inert waste utilised as fill material to minimise the quantity of waste to be disposed of to landfill;
· Proper storage and site practices to minimise the potential for damage or contamination of construction materials; and
· Plan and stock construction materials carefully to minimise amount of waste generated and avoid unnecessary generation of waste.

6.6.3 Good Site Practices

6.6.3.1 Recommendations for good site practices during the construction phase include:
· Nomination of approved personnel, such as a site manager, to be responsible for good site practices, arrangements for collection and effective disposal to an appropriate facility, of all wastes generated at the site;
· Training of site personnel in proper waste management and chemical handling procedures;
· Provision of sufficient waste disposal points and regular collection for disposal;
· Appropriate measures should be employed to minimise windblown litter and dust during transportation of waste by either covering trucks or by transporting wastes in enclosed containers;
· Separation of chemical wastes for special handling and appropriate treatment at the Chemical Waste Treatment Facility; and
· Regular cleaning and maintenance programme for drainage systems, silt traps, sumps and oil interceptors.

6.6.3.2 In order to monitor the disposal of C&D material and solid wastes at public filling facilities and landfills, and to control fly-tipping, a trip-ticket system as described in WBTC No. 21/2002 should be included as one of the contractual requirements and implemented by the contractor.

6.6.3.3 A recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed. Quantities could be determined by weighing each load or other suitable methods.

6.6.3.4 In addition to the above good site practices and waste reduction measures, specific mitigation measures are recommended below for the identified waste arising to minimise environmental impacts during the handling, transportation and disposal of these wastes.

6.6.4 General Site Wastes

6.6.4.1 A collection area should be provided where waste can be stored and loaded prior to removal from site. An enclosed and covered area is preferred to reduce the occurrence of wind-blown light material. If an open area is unavoidable for the storage or loading/unloading of wastes, then the area should be bunded and all the polluted surface run-off collected within this area should be diverted into wastewater treatment system.

6.6.5 Maintenance and Chemical Wastes

6.6.5.1 The chemical waste generated should be labelled, stored and disposed of according to the Waste Disposal (Chemical Waste) (General) Regulation. Registration as a chemical waste producer is required if chemical wastes would be produced. Relevant regulations should be observed and complied with for control of chemical wastes. Proper storage area should be allocated on site for storage of chemical waste. The chemical waste should only be collected by a licensed collector. An updated list of licensed chemical waste collector can be obtained from EPD.

6.6.5.2 The construction contractors / facility operator should adopt the necessary mitigation measures to prevent the uncontrolled disposal of chemical and hazardous waste into air, soil, surface waters and ground waters. Spill adsorbent material and emulsifiers should be available on site in case of spillage. Any contaminated material such as absorbent or cleaning stuffs should be properly disposed of.

6.6.6 C&D Material

6.6.6.1 Components of C&D material such as steel and other metals should be segregated and recycled as far as possible before disposal to landfill.

6.6.6.2 The inert C&D material should be re-used on-site or recycled as far as possible before arranging for disposal of at public filling facilities.

6.6.6.3 For surplus inert C&D material required to be disposed of at public filling facilities, it should be noted that the public filling facilities should only consist of earth, building debris and broken rock and concrete. They should be free from marine mud, household refuse, plastic, metals, industrial and chemical waste, animal and vegetable matter, and other material considered unsuitable by the public filling Supervisor.

6.7 Evaluation of Residual Impacts

6.7.1.1 If appropriate mitigation measures are implemented during the handling, collection, and disposal of waste material, the residual environmental impacts would be reduced to acceptable levels. These mitigation measures can be enforced by incorporating them into a waste management plan as part of the contract document. Environmental monitoring and audit will be necessary to ensure the implementation of correct disposal requirements for the various wastes generated from construction works.

6.8 Conclusions

6.8.1.1 If appropriate mitigation measures are implemented during the handling, collection, and disposal of construction waste material, the residual environmental impacts would be reduced to acceptable levels. These mitigation measures can be enforced by incorporating them into a waste management plan as part of the contract document. Environmental monitoring and audit will be necessary to ensure the implementation of correct disposal requirements for the various wastes generated from construction works.

6.8.1.2 The sludge generated during the operation of the expanded and upgraded San Wai STW should be dewatered to more than 30% dry solids and transported to the landfills. The operators of future UV disinfection facility should work with the supplier/manufacturer on recycling and reuse of the defective UV lamps as far as possible. Should the disposal of UV lamps be unavoidable, the operators should identify the content of the UV lamp and confirm with EPD whether the UV lamps should be disposed of as chemical waste. If so, the handling and disposal should follow the Waste Disposal (Chemical Waste) (General) Regulation. In handling the UV lamps, cautions should be exerted to avoid breakage of lamps and release of contaminants. Unless the spent GAC and scrubbing fluids from the deodorization units are treated on-site, they should be handled and disposed of according to the requirements under the Waste Disposal (Chemical Waste) (General) Regulation.