5 WASTE MANAGEMENT ASSESSMENT

5.1 INTRODUCTION

This Section identifies the key waste management issues during the installation of the proposed pipelines.  In accordance with Clause 3.4.2 of the EIA Study Brief, the following Section includes an analysis of the installation methodology and expected waste generation rates provides an assessment of the impact associated with these activities and presents the proposed waste management plan for the project. 

5.2 LEGISLATIVE REQUIREMENTS AND EVALUATION CRITERIA

The criteria and guidelines for evaluating potential waste management implications are laid out in Annexes 7 and 15 of the EIAO-TM.  The following legislation covers, or has some bearing upon, the handling, treatment and disposal of wastes in the Hong Kong Special Administrative Region (HK SAR), and is considered in the assessment.

* Waste Disposal Ordinance (Cap 354);

* Waste Disposal (Chemical Waste) (General) Regulation (Cap 354);

* Land (Miscellaneous Provisions) Ordinance (Cap 28);

* Public Health and Municipal Services Ordinance (Cap 132)-Public Cleansing and Prevention of Nuisances Regulation; and

* Dumping at Sea Ordinance (Cap. 466).

5.2.1 Waste Disposal Ordinance (Cap 354)

The Waste Disposal Ordinance (WDO) prohibits the unauthorised disposal of wastes, which are defined as any substance or article that is abandoned.  Construction and demolition (C&D) waste is not directly defined in the WDO but is considered to fall within the category of "trade waste".  Trade waste is defined as waste from any trade, manufacturer or business or any wasted building, or civil engineering materials, but does not include animal waste.  Under the WDO, wastes can only be disposed of at a licensed site.  A breach of these regulations can lead to the imposition of a fine and/or a prison sentence.  The WDO also provides for the issuing of licences for the collection and transport of wastes.  Licences are not, however, currently issued for the collection and transport of C&D waste or trade waste.

5.2.2 Waste Disposal (Chemical Waste) (General) Regulation

Chemical waste as defined under the Waste Disposal (Chemical Waste) (General) Regulation includes any substance being scrap material, or unwanted substances specified under Schedule 1 of the Regulation, if such a substance or chemical occurs in such a form, quantity or concentration so as to cause pollution or constitute a danger to health or risk of pollution to the environment.  A person should not produce, or cause to be produced, chemical wastes unless he is registered with the EPD.  Any person who contravenes this requirement commits an offence and is liable to fine and imprisonment.

Producers of chemical wastes must treat their wastes using on-site plant licensed by the EPD or have a licensed collector take the wastes to a licensed facility.  For each consignment of wastes, the waste producer, collector and disposer of the wastes must sign all relevant parts of a computerised trip ticket.  The system is designed to allow the transfer of wastes to be traced from cradle-to-grave.

The Regulation prescribes the storage facilities to be provided on-site including labelling and warning signs.  To minimise the risks of pollution and danger to human health or life, the waste producer is required to prepare and make available written procedures to be observed in the case of emergencies due to spillage, leakage or accidents arising from the storage of chemical wastes.  He/she must also provide employees with training in such procedures.

5.2.3 Land (Miscellaneous Provisions) Ordinance (Cap 28)

The inert portion of construction and demolition materials (C&DM)(1) (also called public fill) may be taken to public filling areas.  Public filling areas usually form part of land reclamation schemes and are operated by the Civil Engineering Department (CED) and others.  The Land (Miscellaneous Provisions) Ordinance requires that individuals or companies who deliver public fill to the public filling areas obtain Dumping Licences.  The licences are issued by the CED under delegated authority from the Director of Lands.

Individual licences and windscreen stickers are issued for each vehicle involved.  Under the licence conditions, public filling areas will accept only inert building debris, soil, rock and broken concrete.  There is no size limit on rock and broken concrete, and a small amount of timber mixed with inert material is permissible.  The material should, however, be free from marine mud, household refuse, plastic, metal, industrial and chemical wastes, animal and vegetable matter and any other materials considered unsuitable by the public filling supervisor.

5.2.4 Public Cleansing and Prevention of Nuisances Regulation

This regulation provides a further control on the illegal dumping of wastes on unauthorised (unlicensed) sites.  The illegal dumping of wastes can lead to a fine and imprisonment.

5.2.5 Dumping at Sea Ordinance (Cap. 466)

This Ordinance came into operation in April 1995 and empowers the Director of Environmental Protection (DEP) to control the disposal and incineration of substances and articles at sea for the protection of the marine environment.  Under the Ordinance, a permit from the DEP is required for the disposal of regulated substances within and outside the waters of the HK SAR.  The permit contains terms and conditions that include the following specifications:

* type and quantity of substances to be dumped;

* location of the disposal grounds;

* requirement of equipment for monitoring the disposal operations; and

* the need for environmental monitoring.

5.2.6 Other Relevant Guidelines

Other 'guideline' documents, which detail how the Contractor should comply with the regulations, are as follows:

* Waste Disposal Plan for Hong Kong (December 1989), Planning, Environment and Lands Branch Government Secretariat;

* Environmental Guidelines for Planning In Hong Kong (1990), Hong Kong Planning and Standards Guidelines, HK Government;

* New Disposal Arrangements for Construction Waste (1992), Environmental Protection Department & Civil Engineering Department;

* Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes (1992), Environmental Protection Department.

* Works Branch Technical Circular, 32/92, The Use of Tropical Hard Wood on Construction Site; Works Branch, HK Government;

* Works Branch Technical Circular No. 2/93, Public Dumps, Works Branch, HK Government;

* Works Branch Technical Circular No. 2/93B, Public Filling Facilities, Works Branch, HK Government;

* Works Branch Technical Circular No. 16/96, Wet Soil in Public Dumps; Works Branch, HK Government;

* Works Bureau Technical Circular No. 4/98 & 4/98A, Use of Public Fill in Reclamation and Earth Filling Projects; Works Bureau, HK SAR Government.

* Works Bureau Technical Circular No 5/98, On-site Sorting of Construction Waste on Demolition Site; Works Bureau, HK SAR Government;

* Waste Reduction Framework Plan, 1998 to 2007, Planning, Environment and Lands Bureau, Government Secretariat;

* Work Bureau Technical Circular No. 25/99, 25/99A and 25/99C, Incorporation of Information on Construction and Demolition Material Management in Public Works Sub-committee Papers; Works Bureau, HK SAR Government;

* Works Bureau Technical Circular No. 12/2000, Fill Management; Works Bureau, HK SAR Government;

* Works Bureau Technical Circular No 29/2000, Waste Management Plan. Works Bureau, HK SAR Government;

* Works Bureau Technical Circular No 19/2001, Metallic Site Hoardings and Signboards; Works Bureau, HK SAR Government;

* Works Bureau Technical Circular No 12/2002, Specifications Facilitating the Use of Recycled Aggregates. Works Bureau, HK SAR Government;

* Works Bureau Technical Circular No 21/2002, Trip-ticket System for Disposal of Construction and Demolition Material.  Works Bureau, HK SAR Government;

* Environment, Transport and Works Bureau Technical Circular (Works) No 33/2002, Management of Construction and Demolition Material Including Rock, Environment, Transport and Works Bureau, HK SAR; and

* Environment, Transport and Works Bureau Technical Circular (Works) No 34/2002, Management of Dredged/Excavated Material, Environment, Transport and Works Bureau, HK SAR.

5.2.7 Management of Dredged/Excavated Sediments for Marine Disposal

Marine disposal of any dredged/excavated sediment is subject to the control of the Dumping at Sea Ordinance (DASO) (1995).  The Ordinance has replaced the Dumping at Sea Act 1974 (Overseas Territories) Order 1975 (App. III p.DK1) in its application in the Hong Kong SAR.  In addition, dredged/excavated sediment destined for marine disposal is classified based on its contaminant levels with reference to the Chemical Exceedance Levels (CEL), as stipulated in Environment, Transport and Works Bureau Technical Circular (ETWBTC) No. 34/2002, Management of Dredged/Excavated Sediment.  This Technical Circular includes a set of sediment quality criteria, as presented below (Table 5.1), which include heavy metals and metalloids, organic pollutants and a new class for highly contaminated sediment not suitable for marine disposal.

Table 5.1     Dredged/Excavated Sediment Quality Criteria for the Classification under ETWBTC No 34/2002.

 

Contaminants

Lower Chemical Exceedance Level (LCEL)

Upper Chemical Exceedance Level (UCEL)

Metals (mg kg-1 dry weight)

 

 

Cd

1.5

4

Cr

80

160

Cu

65

110

Hg

0.5

1

Ni(a)

40

40

Pb

75

110

Silver (Ag)

1

2

Zinc (Zn)

200

270

Metalloid (mg kg-1 dry weight)

Arsenic (As)

12

42

Organic-PAHs (mg kg-1 dry weight)

Low Molecular Weight (LMW) PAHs

550

3160

High Molecular Weight (HMW) PAHs

1700

9600

Organic-non-PAHs (mg kg-1 dry weight)

Total PCBs

23

180

Organometallics (mgTBT l-1 in interstitial water)

Tributyltin (a)

0.15

0.15

Note:

(a)    The contaminant level is considered to have exceeded the UCEL if it is greater than the value shown.

 

The DEP, as the Authority under the DASO, classifies sediments based on their contaminant levels with reference to the Chemical Exceedance Levels (CEL) in the above table.  There are three categories of sediment:

Category L:

Sediment with all contaminant levels not exceeding the Lower Chemical Exceedance Levels (LCEL).  The material must be dredged, transported and disposed of in a manner which minimises the loss of contaminants either into solution or by re-suspension.

Category M:

Sediment with any one or more contaminant levels exceeding the LCEL and none exceeding the Upper Chemical Exceedance Levels (UCEL).  The material must be dredged and transported with care, and must be effectively isolated from the environment upon final disposal unless appropriate biological tests demonstrate that the material will not adversely affect the marine environment.

Category H:

Sediment with any one or more contaminant levels exceeding the UCEL.  The material must be dredged and transported with great care, and must be effectively isolated from the environment upon final disposal.

In addition, in accordance with Building Ordinance Office Practice Note for Authorised Persons and Registered Structural Engineers No 155, any proposal to remove more than 500,000 m3 of clean mud or any quantity of contaminated mud must be justified on both cost and environmental grounds.  The rationale for such removal should also be provided to enable an allocation for disposal to be considered.  It is desirable to demonstrate that any proposed mud dredging is the minimum necessary, and to obtain in-principle agreement from the Geotechnical Engineering Office (GEO) at an early stage.

5.3 EXPECTED WASTE ARISINGS

5.3.1 Construction Phase

During the construction phase, the main activities which will potentially result in waste generation involve excavation and dredging of marine sediments.

The typical waste types associated with these activities include:

* Construction and Demolition Materials (C&DM);

* dredged materials;

* chemical wastes from construction equipment;

* sewage from site staff; and

* general refuse.

5.3.2 Operational Phase

During the operational phase, no solid waste generation is expected after the completion of the laying of the pipelines.

5.4 ASSESSMENT METHODOLOGY

The potential environmental impacts associated with the handling and disposal of waste arisings from the construction and operation of the proposed high pressure submarine gas pipelines was assessed in accordance with the criteria presented in Annexes 7 and 15 of the EIAO-TM, which are summarised as follows:

(a) Prior to considering the disposal options for various types of wastes, opportunities for reducing waste generation, on-site or off-site re-use and recycling shall be fully evaluated. Measures which can be taken in the planning and design stages e.g. by modifying the design approach and in the construction stage for maximizing waste reduction shall be separately considered.

(b) After considering all the opportunities for reducing waste generation and maximizing re-use, the types and quantities of the wastes required to be disposed of as a consequence shall be estimated and the disposal options for each type of waste shall be described in detail. Pretreatment processes for slurry before disposal shall be addressed in details. The disposal method recommended for each type of waste shall take into account of the result of the assessment in (c) below. 

(c) The impact caused by handling (including labeling, packaging & storage), collection, and disposal of wastes shall be addressed in detail and appropriate mitigation measures shall be proposed.

5.5 WASTE MANAGEMENT ASSESSMENT

5.5.1 Construction Phase

C&D Materials

C&D Materials will mainly arise from the construction of the landing point and open trenches for the onshore portion of the pipelines.  The main type of C&D Materials arising from the proposed works will be in form of excavated material.  It is estimated that approximately 270 m3 of excavated materials will be generated from the construction of the landing point.  Assuming 50% of these materials could be used for backfilling, approximately 135m3 of excavated materials will need to be transported off-site.  The construction period for the landfall portion is expected to last for about seven days and hence approximately 19 m3 day-1 of surplus excavated materials will be generated.  This will be associated with about 3 truck trips per day for transporting the materials off-site.

The volume of excavated materials to be generated from the open trenches for the pipelines running along the sea front walkway is estimated to be 2,900 m3 (1 km long, 1.8 m wide and 1.6 m deep).  The construction period for this portion is expected to last about 180 days.  Assuming 50% of these materials could be used for backfilling, 8 m3 per day of surplus excavated materials will need to be transported off-site which associate with just over 1 truck trip per day.

In summary, a total of about 3,200 m3 of surplus excavated materials will be generated within a period of 180 days, of which approximately 50% could be used for backfilling.  All of these materials are expected to be inert and could be reused at other reclamation or land formation projects

Dredged Materials

The pipelines will be laid under the seabed by a combination of jetting and dredging, depending the level of protection required.  Only dredging will generate marine sediments which require disposal and it is estimated that approximately 220,000 m3 of these materials will need to be dredged for the laying of pipelines within Mirs Bay (see Figure 4.3a).  No dredging operation occurs in proximity of Tung Ping Chau within Hong Kong waters.

Based on the results of marine sediment quality sampling conducted by the EPD(2) in Mirs Bay (MS17 and MS5), all the sediments are classified as Category L (uncontaminated).  A summary of the Sediment Quality Data is presented in Section 4 - Table 4.3.  According to ETWBTC 34/2002 - Management of Dredged/Excavated Sediment, the material is suitable for Type 1 - Open Sea Disposal Method.  The uncontaminated dredged materials could be disposed of at the East Nine Pin Disposal Area or South Cheung Chau Disposal Area.  The final allocation of the disposal site shall be agreed with the DEP in conjunction with the Marine Fill Committee. It should be noted that further sampling and testing requirements may be specified by DEP in due course on application for a DASO permit.  It is not anticipated that the disposal of the uncontaminated dredged material at the designated disposal area will cause adverse environmental impacts if the sediment is properly handled, transported and disposed of in accordance with the ETWBTC 34/2002 and DASO permit.  The potential water quality impacts associated with the dredging works are described in Section 4.

Chemical Waste from Construction Equipment

Chemical waste, as defined under the Waste Disposal (Chemical Waste) (General) Regulation, includes any substance being scrap material, or unwanted substances specified under Schedule 1 of the Regulation.  A complete list of such substances is provided under the Regulation; however, substances likely to be generated during the construction programme will, for the most part, arise from the maintenance of equipment.  These may include, but need not be limited to the following:

* scrap batteries or spent acid / alkali from their maintenance;

* used paint, engine oils, hydraulic fluids and waste fuel;

* spent mineral oils / cleaning fluids from mechanical machinery; and

* spend solvents / solutions, some of which may be halogenated, from equipment cleaning activities.

Chemical wastes 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 and the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes.  These hazards may include:

* toxic effects on workers;

* adverse effects on air, water and land from spills; and

* fire hazards.

It is difficult to quantify the amount of chemical waste that will arise from the construction activities as it will be highly dependent on the Contractor's on-site maintenance activities and the quantity of plant and equipment utilised.  However, it is anticipated that the quantity of chemical waste, such as lubricating oil and solvent produced from plant maintenance will be small and in the order of a few hundred litres per month.  The chemical waste to be generated from the construction activities may be disposed of at the Chemical Waste Treatment Centre (CWTC) at Tsing Yi.

The storage, handling, transportation and disposal of chemical wastes shall be in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Waste published by the EPD.   The potential environmental impacts associated with the handling, storage and disposal of the small amount of chemical waste to be generated from the construction activities is anticipated to be negligible, subject to the adherence of the above-mentioned Code of Practice.

Sewage from the Construction Workforce

Sewage arisings will be generated from :

* the construction workforce;

* the site office's sanitary facilities; and

* night soil from portable toilets. 

If not properly managed, the untreated sewage could cause odour and potential health risks to the workforce by attracting pests and other disease vectors. 

The exact number of construction workers to be employed on-site is unavailable at this stage; however given the minor scale of the construction works, it is expected to be small (approximately 20 workers during peak construction period).  An adequate number of portable toilets should be provided at the onshore worksites to ensure that sewage from site staff is properly collected.  With respect to the small area of the site onshore, it is considered that portable toilets to be located at 2 main works areas of the site will be adequate.  However, the detailed requirements will be determined in the Waste Management Plan to be submitted by the Contractors and agreed by Towngas.  No adverse environmental impacts are envisaged provided that the portable toilets are properly maintained by licensed contractors and the collected sewage is disposed of at the Tai Po Sewage Treatment Works.

General Refuse

A variety of general refuse will be generated by the on-site construction workforce.  General refuse requiring disposal will mainly consist of food waste, aluminium cans and waste paper.

The storage of general refuse has the potential to give rise to adverse environmental impacts.  These include odour if the waste is not collected frequently (for example, daily), windblown litter, water quality impacts if waste enters water bodies, and visual impact.  The sites may also attract pests, vermin, and other disease vectors if the waste storage areas are not well maintained and cleaned regularly.  Inappropriate disposal of wastes at sites other than approved landfills, may also lead to similar adverse impacts at those sites.

The exact number of workers to be employed for the project is not available at this stage; however, it is expected to be small (approximately 20 workers during peak construction period). Assuming a generation rate of 0.65kg per person per day, approximately 13kg day-1 of general refuse will be generated during the peak construction period.  Provided that the mitigation measures recommended in Section 5.6 are adopted, the environmental impacts caused by the storage, handling, transport and disposal of general refuse are expected to be minimal.  It is recommended that the general refuse be collected daily by reputable waste collectors. 

5.5.2 Operational Phase

There is no maintenance dredging required for the pipelines as the inspection of the pipelines is conducted remotely using a pipe inspection gauge (PIG).  As such, no waste generation is expected after the completion of the installation of the pipelines.  Should any emergency repairs of the submarine pipelines be required then divers operating hand jets will perform the work.  No offsite disposal of sediments will be required.

5.6 MITIGATION OF ADVERSE IMPACTS

5.6.1 Introduction

This Section outlines the mitigation measures recommended to avoid or minimise potential adverse environmental impacts associated with the handling, collection and disposal of waste arising from the project.  The Contractors shall incorporate these recommendations into a Waste Management Plan for the construction works and shall submit the plan to Towngas for approval prior to the commencement of works.  The Waste Management Plan should incorporate site-specific factors, such as the designation of areas for the segregation and temporary storage of reusable and recyclable materials.  An Outline Waste Management Plan has been prepared in the EIA report as Annex H.  It provides an outline of the roles and responsibilities of the main contractual parties involved with the management of wastes arising from the Contract.  The Contractor can use it as a basis for the development of a detailed Waste Management Plan.

It is the Contractor's responsibility to ensure that only reputable or licensed waste collectors are used and that appropriate measures to minimise adverse impacts, including windblown litter and dust from the transportation of these wastes are employed.  In addition, the Contractor shall ensure that all the necessary waste disposal permits are obtained throughout the construction phase.

5.6.2 Construction Phase

Excavated Material

Wherever practicable, excavated materials should be segregated from other wastes to avoid contamination, thereby ensuring acceptability at the public filling facilities and avoiding the need for disposal at landfill.

Measures Taken in the Planning and Design Stages to Reduce the Generation of C&DM

The various waste management options can be categorised in terms of preference from an environmental viewpoint.  The options considered to be more preferable have the least impacts and are more sustainable in the long term.  Hence, the waste management hierarchy is as follows:

* avoidance and minimisation, that is, reduction of waste generation through changing or improving practices and design;

* reuse of materials, thus avoiding disposal (generally with only limited reprocessing);

* recovery and recycling, thus avoiding disposal (although reprocessing may be required); and

* treatment and disposal, according to relevant law, guidelines and good practice.

This hierarchy should be used to evaluate the waste management options, thus allowing maximum waste reduction and often reduced costs.  For example, by reducing or eliminating over-ordering of construction materials, waste is avoided and costs are reduced both in terms of the purchase of raw materials and in disposing of wastes.  Records of quantities of wastes generated, recycled and disposed (locations) shall be kept.

Recommended Construction Phase Measures for the Reduction of C&DM Generation

The Contractor shall recycle as much of the C&DM as possible on-site.  Public fill and C&D waste shall be segregated and stored in different containers or skips to facilitate reuse or recycling of materials and their proper disposal.  Specific areas of the work site should be designated for such segregation and storage if immediate use is not practicable.

The use of wooden hoardings shall not be allowed.  An alternative material, which can be reused or recycled, for example, metal (aluminium, alloy, etc), shall be used. 

Government has developed a charging policy for the disposal of waste to landfill.  When it is implemented, this will provide an additional incentive to reduce the volume of waste generated and to ensure proper segregation to allow reuse of the excavated material.

Dredged Materials

Dredged marine mud shall be disposed of in a gazetted marine disposal area in accordance with the DASO permit conditions.

Chemical Waste

Chemical waste producers should be registered with the EPD.  For those processes which generate chemical waste, it may be possible to find alternatives which generate reduced quantities or even no chemical waste, or less dangerous types of chemical waste.

Chemical waste, as defined by Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation, should be handled in accordance with the Code of Practice on the Packaging, Handling and Storage of Chemical Wastes as follows.  Containers used for storage of chemical wastes should:

* be suitable for the substance they are holding, resistant to corrosion, maintained in a good condition, and securely closed;

* have a capacity of less than 450 L unless the specifications have been approved by the EPD; and

* display a label in English and Chinese in accordance with instructions prescribed in Schedule 2 of the Regulations.

The storage area for chemical wastes should:

* be clearly labelled and used solely for the storage of chemical waste;

* be enclosed on at least 3 sides;

* have an impermeable floor and bunding, of capacity to accommodate 110% of the volume of the largest container or 20% by volume of the chemical waste stored in that area, whichever is the greatest;

* have adequate ventilation;

* be covered to prevent rainfall entering (water collected within the bund must be tested and disposed of as chemical waste, if necessary); and

* be arranged so that incompatible materials are appropriately separated.

Disposal of chemical waste should be:

* via a licensed waste collector; and

* to a facility licensed to receive chemical waste, such as the Chemical Waste Treatment Facility which also offers a chemical waste collection service and can supply the necessary storage containers.

Sewage

An adequate number of portable toilets should be provided for the on-site construction workforce.  The portable toilets shall be maintained in a state that will not deter the workers from using them.  Night soil should be regularly collected by a licensed collector for disposal at the Tai Po Sewage Treatment Works.

Management of General Refuse

General refuse should be stored in enclosed bins or compaction units separately from construction and chemical wastes.  A reputable waste collector should be employed by the Contractor to remove general refuse from the site, separately from construction and chemical wastes, on a daily basis to minimise odour, pest and litter impacts.  The burning of refuse on construction sites is prohibited by law.

Aluminium cans are often recovered from the waste stream by individual collectors if they are segregated and made easily accessible.  As such, separate, labelled bins for their deposit should be provided if feasible.

Office wastes can be reduced through the recycling of paper if volumes are large enough to warrant collection.  Participation in a local collection scheme should be considered if available.  In addition, waste separation facilities for paper, aluminium cans, plastic bottles etc., should be provided.

Management of Waste Disposal

A trip-ticket system should be established in accordance with Works Bureau Technical Circular No. 21/2002 to monitor the disposal of solid wastes at transfer station/landfills, and to control fly-tipping.  A trip-ticket system will be included as one of the contractual requirements and implemented by the Towngas.  Towngas should also conduct regular audits of the results of the system.

A recording system for the amount of waste generated, recycled and disposed of (including the disposal sites) should be established during the construction stage.

Staff Training

Training should be provided to workers on the concepts of site cleanliness and on appropriate waste management procedures, including waste reduction, reuse and recycling at the beginning of the Contract.

5.6.3 Operational Phase

No mitigation measures are required.

5.7 RESIDUAL ENVIRONMENTAL IMPACTS

With the implementation of the recommended mitigation measures, in particular the establishment and implementation of the Waste Management Plan, minimal residual impacts are anticipated from the construction of the proposed Project.

5.8 ENVIRONMENTAL MONITORING AND AUDIT

It is recommended that audits should be carried out on a monthly basis during the construction phase to determine whether wastes are being managed in accordance with the Waste Management Plan.  The audits should address all aspects of waste management, including waste generation, storage, recycling, transportation and disposal.  An appropriate audit programme would be to undertake a first audit at the commencement of the construction works and then monthly audits, thereafter.

5.9 CONCLUSIONS

This Section identifies the key waste management issues during the installation of the proposed pipelines.  The installation methodology and expected waste generation rates were examined.  An impact assessment for these activities was undertaken and a Waste Management Plan has been proposed for the Project.

It is expected that the following identified waste types will be generated from the construction of the Project:

* C&D Materials - approximately 3,200m3 of excavated materials will be generated within a period of 180 days, of which approximately 50% could be used for backfilling;

* A total of about 220,000 m3 of uncontaminated (Category L) dredged materials will need to be disposed of at the designated marine dumping areas;

* chemical waste (in the order of hundreds of litres);

* sewage from the on-site construction workforce; and

* general refuse (approximately 13kg day-1 during peak construction).

The quantity of waste materials arising from the construction phase is not expected to be unduly high, but practical measures will be taken to avoid, minimise and recycle wastes.  Mitigation measures relating to good practice have been recommended to ensure that adverse environmental impacts are prevented and that opportunities for waste minimisation and recycling are followed.  With the implementation of the recommendations, the potential environmental impacts associated with the storage, handling, collection, transport, and disposal of wastes during construction will meet the criteria specified in the EIAO TM.  No unacceptable environmental impact is anticipated.

No waste generation is expected after the completion of the installation of the pipelines, hence mitigation measures are not required.

 

_______________________

(1)  "C&DM" refers to surplus materials arising from any land excavation or formation, civil/building construction, road works, building renovation or demolition activities.  It includes various types of reusable materials, building debris, rubble, earth, concrete, timber and mixed site clearance materials. When sorted properly, materials suitable for land reclamation and site formation (known as public fill) should be reused at public filling areas whereas the remaining C&D waste are to be disposed of at landfills.

(2) Marine Water Quality in Hong Kong in 2000, EPD, November 2001.