6.15          Impact Summary

Table 6.15a - Impacts Summary Table for NLDFS

Issue

Construction Impact

Operation Impact

Assessment Points

NLDFS Study Area

NLDFS Study Area

Relevant Criteria

Waste Disposal Ordinance, Waste Disposal (Chemical Waste) (General) Regulation, Land (Miscellaneous Provisions) Ordinance, Public Health and Municipal Services Ordinance, Dumping at Sea Ordinance, Waste Disposal Plan for Hong Kong, New Disposal Arrangements for Construction Waste, Code of Practice on the Packaging, Labelling and Storage oe Chemical Wastes, EPDTC 1-1-92, WBTC Nos. 6/92, 22/92, 32/92, 2/93, 16/96, 4/98, 5/98, 5/99 and 25/99, and Waste Reduction Framework Plan.

Waste Disposal Ordinance, Waste Disposal (Chemical Waste) (General) Regulation, Public Health and Municipal Services Ordinance, Waste Disposal Plan for Hong Kong, Environmental Guidelines for Planning in Hong Kong and Waste Reduction Framework Plan.

Potential Impact

Dredged/Excavated Sediment

Due to the detection limit of PAHs and PCBs being higher than LCEL, further testing of PAHs and PCBS for all the sediment to be dredged will be required to confirm proper classification.  In addition, the testing of TBT in interstitial water should be used instead, in accordance to the new excavated/dredged sediment guidelines.

At Penny’s Bay reclamation and Yam O reclamation, approximately 0.11 M m3 is seriously contaminated (Class C). The Class C sediment should be disposed of at the East Sha Chau Contaminated Mud Pits. No adverse environmental impact is anticipated if the Class C sediment is properly transported to and disposed.  FMC has allocated 30 M m3 of uncontaminated and disposal capacity to the Penny’s Bay Project (East Nine Pin, East Tung Lung and North Lantau).  The Engineers should inform FMC the extra volume of sediment requiring disposal so further disposal grounds can be allocated.

For Northshore reclamation, approximately 60,000 m3 of dredged sediment would required confined marine disposal.  However, this volume may increase as additional biological screening is required to determine the disposal route for sediment exceeding LCEL. 

At Siu Ho Wan reclamation, the sediment to be dredged are likely to be uncontaminated, although checking on exceedance on LCEL in terms of PAHs, PCBs and TBT (in interstitial water) will be required.

The sediment at SDU reclamation and Road P1 reclamation are not likely to be seriously contaminated.  However biological screening should be carried out to determine whether confined marine disposal is required and further testing on PAHs, PCB and TBT (in interstitial water) are needed.

Biological screening is required at TCT East reclamation to determine the disposal route of dredged sediment although it is estimated that approximately 70,000 m3 will required confined marine disposal.  Further testing on PAHs, PCBs and TBT (in interstitial water) will also required to check if there is any exceedance in LCEL.  

When the volume of sediment requiring confined/open marine disposal is confirmed, during detailed design stage, the FMC should be informed in order to allocate suitable disposal sites(s).

Municipal Solid Waste

Based on the current development options, the amount of waste to be generated will be 335.13 tpd (without any waste reduction/recycling) when the Northshore Lantau Development is in full operation. Significant amounts of waste will be generated from the tourism related developments (314.05 tpd). This estimation should be refined during detailed design stage. 

The disposal of waste from NLDFS development to strategic landfill will via NLTS.  Since the information on NLTS throughput forecast only up to 2016, although the NLDFS developments will be fully operate later than 2016, comparison is made to see if the NLTS can receive the waste arisings from NLDFS development.  The anticipated quantity of waste arising from the NLDFS developments would constitute an significant increase of the daily throughput (at least 38 %, see Section 6.5) in the waste arising from the catchment area of the NLTS which has a design capacity of 1,200  tpd. According to the current waste arisings prediction, the NLTS will not be able to handle the waste generated within its catchment area (deficiency of approximately 15 tpd).  With proper implementation of the waste reduction and waste management plan, no insurmountable impacts associated with the handling and disposal of waste will be expected.

The floating refuse from windblown refuse and litter may vary from small debris to large floating objects such as plastic bags.  The floating refuse is likely to be chemically inert, however, if not collected properly, these floating refuse may drift along the coastal area of the Theme Park and associated developments and the artificial lake of the Water Recreation Centre, which may create aesthetic or odour impact, or cause damage to marine craft.  Provided that mitigation measures such as the use of surface boom to contain the floating refuse, are properly implemented, no insurmountable environmental impacts with regards to floating debris will be anticipated.

 

Use of Public Fill for Reclamation

Penny’s Bay Reclamation (Stages I and II) requires about 85.4 M m3 of filling material including surcharge, 10.5M m3 of public fills has been planned will be included into the reclamation, the maximum uptake due to various constraints.  And the Yam O Reclamation will use about 1.7 M m3 of filling material, of which 1.0 M m3 is public fill.

The total amount of fill requirements for other reclamations within the Project Area is 43.8 M m3.  It is estimated approximately 34.4 M m3 (about 78%) of public fill will be utilised at those reclamations.  Also, an extra 17.5 M m3 of public fill will be used as surcharge.  The use of public fill will not only alleviate the demand for virgin fill material but also reduce the pressure of disposing inert construction and demolition material at the strategic landfills

 

Excavated Material

 

The construction of the building foundation for the NLDFS infrastructures (including at Penny’s Bay Reclamation Stages I and II, Theme Park and NLDFS developments as well as other roads and drains) will generate some excavated materials.  The quality of the excavated material will be the same as the fill materials used for the reclamation ( ie either marine sand fill or clean public fill).  The exact amount of surplus excavated material to be generated from the foundation works cannot be determined until detailed design information is available.  However, it is anticipated that the excavated material to be generated will be of a small percentage (less than 5%) to the fill requirements (117.6 M m3) for all the reclamations and can all be reused, either on-site or at adjacent reclamation, as fill materials

About 7,800 m3 of excavated material will be generated from the excavation works for Road P2.  The excavated materials will be reused on-site for filling at Cheoy Lee Shipyard area and no surplus excavated material will be generated.

Approximately 68,500 m3 of excavated materials from cut and cover, drill and blast tunnel works for the PBRL will be generated between January 2003 and June 2004 (approximately 18 months) and will comprise mainly clean rock and soil.  The Yam O station will be constructed on pad foundation, and hence no piling will be required.  The Penny's Bay Rail Station will be seated on steel H-piles or pad foundation. 

Recycling

According to the assessment carried out for the Theme Park Phases I and II  ([29]),the market driven recycling industry can recycle 23-26 % of waste to be generated in the tourism related developments.  It is recommended that a additional further target of an additional 10% for recyclable recovery programme at these developments and potentially, an extra 10% for food waste source separation (assuming that a composting facility for food waste planned in the Waste Reduction Framework Plan is available) programme be adopted in the Waste Management Plan of the tourism related developments.

 

Disposal

 

According to Table 6.6a and based on the waste arisings from the NLDFS developments and associated facilities and market driven recycling rate of 23-26 % for tourism related developments, the daily waste arisings after market driven recycling in full operation is at least 253.48 to 262.9 tpd.  The tourism related development recommended recyclable recovery programme can further reduce waste by an additional 10 %, which is 31.41 tpd.  In addition, if  food waste composting facility is available in HK SAR, an extra 10 % of waste (i.e. 31.41 tpd) to be generated from the tourism related developments can be reduced.

The anticipated waste throughout of NLTS are 370, 770, and 880 tpd for the years 2006, 2011 and 2016, respectively.  It indicates that there will be sufficient spare capacity at the NLTS to handle the waste arising from the NLDFS developments at least to year 2016.

 

 

A total of approximately 3.0 M m3 of excavated is expected to be generated from the construction of the CKWLR, primary as a result of excavation at slopes of Pa Tau Kwu. Small amounts of excavated material will also expected from the foundation works carried out at CKWLR Phases I and II.  The daily generation rate is 3,000 m3 d-1.  Excavated material generated at Yam O to Penny’s Bay Interchange could be reused on-site for filling at the Cheoy Lee Shipyard area.  Whereas excavated material generated at Pa Tau Kwu and CKWLR Phases I and II could be re-used within other NLDFS reclamation such as Penny’s Bay Reclamation Stage II or Theme Park (Phase III) Extension reclamation.  No surplus excavated material will be generated.

As all the reclamations require a large quantity of fill material and the Project will have an overall deficit of fill material.  It is anticipated that all the excavated soil and rock generated from the Project will be re-used for the reclamation works.  Since public filling areas only accept public fill with certain size (< 200 mm diameter).  Some of the excavated material may require to be broken prior re-use on site.  No surplus of excavated material will be generated.

 

C&D Waste

 

Small amount of demolition waste will be generated at Cheoy Lee Shipyard and Ngong Shuen Au for the construction of CKWLR.  However, the small is likely to be small.   However, there are potential environmental impacts associated with the decommissioning and demolition of the shipyard is addressed in Section 12 and will be evaluated under a separate Schedule 2 EIA to be commissioned by the CED.

During the infrastructure construction period, the highest cumulative daily C&D waste arisings is during 2004 and will be generated from Theme Park Phase I Opening Day, Theme Park Phase II Buildout, GIC at area 1B, Water Recreation Centre, SDU Base and PBRL during Q2 2004 (the average and peak C&D waste generation rate is 32 m3 d-1 and 49 m3 d-1, respectively, whereas for public fill generation rate is 131 m3 d-1 and 198 m3 d-1).

Chemical Waste

 

The operation of the Theme Park at Penny’s Bay will use a variety of chemicals.  Some of the used chemicals have to be disposed of.  The operation of the Theme Park at Penny’s Bay will be very similar to that of Disneyland.  In addition, the remains of fireworks from the fireworks shows in the Theme Park may contain heavy metal in low concentrations (in a scale of  ng kg-1).

Chemical waste will be stored, handled, transported and disposed of in accordance with the Waste Disposal (Chemical Waste) (General) Regulation and the Code of Practice on Packaging, Labelling and Storage of Chemical Wastes.  They should be collected and transported to the CWTC or other licensed facility by a licensed waste haulier.

 

Sewage Sludge

 

Based on sludge generation rate of 18,702 tds a-1 in 2016, approximately 40 tds per day of sludge will be generated, which is equivalent to approximately 170 m3 of sludge.  10 m3 skips (as currently employed in Sha Tin STW) could be used for transportation of sludge to the disposal facility.  A maximum of 17 truck loads will be required.  It is therefore considered that the traffic impacts associated with off-site sludge disposal will be minimal.

Should the proposed centralised Sludge and Difficult Wastes Incineration Facility (SDIF) be located near the WENT landfill, it will be more cost effective and environmentally preferred to transport  the sludge in modified 20ft ISO containers (similar to the one currently used at the Stonecutters’ Island STW) via the NLTS to the WENT Landfill Reception Area and then to the SDIF..

 

Chemical Waste

 

A small volume of chemical waste, such as used lubricating oils from plant maintenance materials, will be produced.  Provided chemical wastes are disposed of at a licensed facility, the contractor should be in compliance with all relevant regulations and there will be little environmental impact.

 

General Refuse

 

The maximum daily number of workers on site is 6,000.  Based on a waste generation rate of about 0.65 kg per person, it is estimated that the amount of general refuse to be generated will be in the order of 3.9 tpd.

Biogas Assessment

 

Given that, at this stage, it is not possible to measure the rates of gas emission from the organic sediment within the area of the proposed artificial lake of Water Recreation Centre in the Theme Park, Penny’s Bay Reclamation Stage II, Yam O Reclamation, Northshore Reclamation, Siu Ho Wan Reclamation, SDU Reclamation, Road P1 Reclamation, Theme Park (Phase III) Extension Reclamation and TCT East Reclamation (hereafter refer as undredged areas), an estimate of the future rate of gas generation has been made from the results of analysis of the sediment for TOC and SOD.

 

Several assumptions and estimations have to be made when making theoretical predictions about possible future rates of methane generation at the undredged areas.  The estimated potential rates of methane gas generation based on both TOC and SOD are within the maximum safe rate (3.6 l m-2 d-1) of methane emission from landfill sites which is specified by the UK Department of Environment in WMP26A as indicating that such sites can be regarded as no longer posing a threat due to gas and are safe to be developed. They are well within the suggested maximum rate of methane emission per unit area of 10 l m2 d-1, and the limit of 84.7 l m2 d-1 recommended by the London Scientific Services.  The former criterion provides a reasonable general guide for determining whether the rates of methane emission pose an unacceptable risk to unrestricted development on a potentially gassing site.  The latter criterion represents the absolute ‘cut-off’ level of methane flux which developments should be allowed to build on the potentially gassing site.

 

Overall, based on the results of the sediment analysis and comparison with published guidance on safe levels of gas emissions, it is considered the predicted rates of gas generation from the undredged areas are within the range which are considered as ‘likely be safe’ and will not constraint the developments on top of the reclamation areas.

 

Given the inherent uncertainties involved in estimating future rates of gas emissions from theoretical calculations of rates of gas generation and given that mitigation measures for avoiding the potential risks may be very expensive, it would be of benefit to select one of the undredged areas to undertake monitoring of gas emission rates following the construction works to confirm the findings of this assessment.  It is recommended that the monitoring boreholes should be installed in areas where the predicted methane flux is high and at areas to be reclaimed first so that the monitoring results will be available as soon as possible. Should the monitoring results show that biogas may be a problem, further monitoring boreholes could  then be installed at other reclamation areas.  Based on these criteria (see Tables 6.5a, 6.14g and 6.14h), it is recommended that monitoring boreholes should be installed at the Water Recreation Centre of the Theme Park.

Mitigation Measures

The Contractor should development a Waste Management Plan to Engineer approval prior to construction.  Such a management plan should incorporate site specific factors, such as the designation of areas for the segregation and temporary storage of reusable and recyclable materials.

 

Dredged/Excavated Sediment

·       minimising exposure to any contaminated material by the wearing of protective gear such as gloves, providing adequate hygiene and washing facilities, and preventing eating during dredging/excavation;

·       any contaminated sediment dredged should not be allowed to stockpile on the site and should be immediately removed from site once dredged;

·       all vessels for marine transportation of dredged sediment should be fitted with tight fitting seals to their bottom openings to prevent leakage of materials; and

·       loading of barges and hoppers should be controlled to prevent splashing of dredged material to the surrounding water, and barges or hoppers should under no circumstances to be filled to a level which will cause other overflowing of materials or polluted water during loading or transportation.

 

Use of Public Fill for the reclamation

 

The Contractor should enforce strict application of the public fill license and monitor the material placed in the reclamation and barges to control disposal of unauthorised material.  The Contractor shall also provide floating booms and collect any floating materials on a daily basis at the public filling areas.

 

Excavated Material

 

Wherever practicable, excavated materials should be segregated from other wastes to avoid contamination thereby ensuring acceptability at public filling areas or reclamation sites and avoiding the need for disposal at landfill.  The priority for off-site disposal of surplus excavated material should be as follows:

 

·       transport to other reclamation sites at North Lantau and Penny's Bay areas; and

·       transport to public filling areas.

The tourism related development operators try to minimise the amount of waste to be disposed of at landfill and to maximise the recovery of material from the waste stream, these operators should will implement a waste prevention and recycling programme.  The waste avoidance measures and material recovery and recycle programme will form part of the Waste Management Plan for the operation and management of the tourism related developments.

To minimise the potential adverse impacts to aesthetics and odour impacts, floating refuse collection initiatives at both the coast of the reclamation and within the artificial lake of the Water Recreation Centre of the Theme Park should be carried out.

 

Chemical Waste

 

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 that is produced, 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.

 

 

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

 

·       avoidance and minimisation, that is, not generating waste 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 reducing costs.  For example, by reducing or eliminating over-ordering of construction materials, waste is avoided and costs are reduced both in terms of purchasing of raw materials and in disposing of wastes.  Records of quantities of wastes generated, recycled and disposed (locations) should be properly kept.

 

Standard formwork should be used as far as practicable in order to minimise the arisings of C&DM.  The use of more durable formwork or plastic facing for the construction works should be considered during the detailed design.

 

Any uncontaminated soil should be reused on site as far as possible for landscape works in order to minimise the amount public fill to be disposed off-site. Should there be any surplus public fill generated from the project, the HKITP should liaise with the Public Filling Sub-Committee to identify as far as possible suitable reclamation or site formation projects near the project site to reuse the material.

 

The design of the foundation works will minimise the amount of excavated material to be generated.  Should piling be required, H-piling will be used as far as practical.

 

The purchasing of construction materials will be carefully planned in order to avoid over ordering and wastage of construction materials, such as ready mixed concrete.

The storage area for chemical wastes should:

 

·       by 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 as chemical waste if necessary); and

·       be arranged so that incompatible materials are adequately separated.

 

Disposal of chemical waste should:

 

·       be via a licensed waste collector; and

 

·       be 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; or

 

·       be to a re-user of the waste, under approval from the EPD.

 

The Centre for Environmental Technology operates a Waste Exchange Scheme which can assist in finding receivers or buyers

 

Sewage Sludge

 

The containment, storage and delivery of the sewage sludge should be enclosed.  Odour removal facilities should also be installed to minimise the potential air quality impacts to any sensitive receivers.

 

 

Measures To be Taken in the Construction Stage To Reduce the Generation of C&DM

 

The Contractor should recycle as much as possible of the C&D material on-site.  Public fill and C&D waste should be segregated and stored in different containers or skips to enhance reuse or recycling of materials and their proper disposal.  Concrete and masonry, for example can be crushed and used as fill and steel reinforcing bar can be used by scrap steel mills.  Different` areas of the work sites should be designated for such segregation and storage.

 

At present, Government is developing a charging policy for the disposal of waste to landfill.  When it is implemented, this will provide additional incentive to reduce the volume of waste generated and to ensure proper segregation to allow disposal of inert material to public filling areas.

 

In order to minimise the impacts of the demolition works these wastes must be cleared as quickly as possible after demolition.  The demolition and clearance works should therefore be undertaken simultaneously.

 

Chemical Waste

 

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 that is produced, 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.

Biogas Assessment Monitoring

 

As discussed above, a number of assumptions and estimations have to be made when theoretically estimating the rate of gas generation.  This means that the estimate of future rates of gas generation can provide only an indication of the likely rate of gas emission.  In order to determine more accurately the risk related to biogas emissions from the organic sediment at the undredged areas, therefore, it is recommended that monitoring of the artificial lake of Water Recreation Centre in the Theme Park should be undertaken following completion of the construction works.  This will enable actual rates of gas emission to be determined and will ensure that account is taken of the effect of changing atmospheric pressure on the behaviour of the gas reservoir which may accumulate within the reclamation fill above the gas producing organic sediments.

As it is not practicable to install monitoring wells over the impermeable membrane of the artificial lake due to potential leakage of water into monitoring wells, it is recommended that monitoring wells should install in the edge of the artificial lake of Water Recreation Centre where sediment will be left in situ (see Figure 6.14b).

 

It may take some time for fully anaerobic conditions to be established within the organic sediment and for a reservoir of gas to accumulate within the reclamation fill so monitoring should be undertaken for as long as possible prior to the commencement of construction works at the Water Recreation Centre.  Ideally, monitoring should be undertaken for a period of at least one year prior to the commencement of construction.

 

If there is only limited time between completion of the reclamation and commencement of construction at Water Recreation Centre, monitoring should commence immediately upon completion of the reclamation so that any trends may be observed and results extrapolated to the period of construction and occupation of the development.

 

Monitoring should be undertaken via purposely installed monitoring wells installed within boreholes drilled into the fill material.  The boreholes should be drilled down to the level of the groundwater (mean sea water level) and standard landfill gas-type monitoring wells should be installed.  These should be fitted with a removable cap and gas monitoring valve so that gas concentrations may be measured as well as flow rates from the open well.

 

It is recommended that two monitoring wells should be installed across the area of the Water Recreation Centre (Figure 6.14b).  These should be located such as to give an approximately even distribution across the whole area.  If they are located within areas designated for open space, it may be possible to retain them for future long-term monitoring.  The wells should be monitored as follows:

·       concentrations of the following gases should be measured using portable monitoring equipment with gas chromatographic (GC) analysis being undertaken on selected samples to confirm the results:

·       methane

·       carbon dioxide

·       oxygen

·       gas flow rates from the open wells - very sensitive techniques (such as micro-anemometer) will need to be used to measure the anticipated very low flow rates.

 

The monitoring schedule will depend on the relative timing of the reclamation and subsequent construction works.  Ideally, the boreholes should be drilled and the monitoring wells installed as soon as possible after the completion of the reclamation works.  Monitoring should then take place over a period of at least one year with the emphasis on the second part of the year.  It will be important to monitor gas flows from the wells under different meteorological conditions and to include some occasions when atmospheric pressure is falling quite quickly (e.g. immediately proceeding a typhoon).

 

The storage area for chemical wastes should:

 

·       by 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 as chemical waste if necessary); and

·       be arranged so that incompatible materials are adequately separated.

 

Disposal of chemical waste should:

 

·       be via a licensed waste collector; and

·       be 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; or

·       be to a re-user of the waste, under approval from the EPD.

 

The Centre for Environmental Technology operates a Waste Exchange Scheme which can assist in finding receivers or buyers.

 

Management of General Refuse

 

General refuse generated on-site should be stored in enclosed bins or compaction units separate 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.

 

General refuse is generated largely by food service activities on site, so reusable rather than disposable dishware should be used if feasible.  Aluminium cans are often recovered from the waste stream by individual collectors if they are segregated of easily accessible, so separate, labelled bins for their deposit should be provided if feasible.

 

Office wastes can be reduced through recycling of paper if volumes are large enough to warrant collection.  Participation in a local collection scheme should be considered if one is available.  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 5/99 to monitor the disposal of C&DM and solid wastes at public filling facilities and landfills, and to control fly-tipping.  A trip- ticket system will be included as one of the contractual requirements and implemented by the Engineer.  The Engineer should audit the result 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.

Biogas Assessment Monitoring

 

A number of assumptions and estimations have to be made when theoretically estimating the rate of gas generation.  This means that the estimate of future rates of gas generation can provide only an indication of the likely rate of gas emission.  In order to determine more accurately the risk related to biogas emissions from the organic sediment at the undredged areas, therefore, it is recommended that monitoring of the artificial lake of Water Recreation Centre in the Theme Park should be undertaken following completion of the construction works.  This will enable actual rates of gas emission to be determined and will ensure that account is taken of the effect of changing atmospheric pressure on the behaviour of the gas reservoir which may accumulate within the reclamation fill above the gas producing organic sediments.

 

As it is not practicable to install monitoring wells over the impermeable membrane of the artificial lake due to potential leakage of water into monitoring wells, it is recommended that monitoring wells should install in the edge of the artificial lake of Water Recreation Centre where sediment will be left in situ (see Figure 6.14b).

 

It may take some time for fully anaerobic conditions to be established within the organic sediment and for a reservoir of gas to accumulate within the reclamation fill so monitoring should be undertaken for as long as possible prior to the commencement of construction works at the Water Recreation Centre.  Ideally, monitoring should be undertaken for a period of at least one year prior to the commencement of construction.

 

If there is only limited time between completion of the reclamation and commencement of construction at Water Recreation Centre, monitoring should commence immediately upon completion of the reclamation so that any trends may be observed and results extrapolated to the period of construction and occupation of the development.

 

Monitoring should be undertaken via purposely installed monitoring wells installed within boreholes drilled into the fill material.  The boreholes should be drilled down to the level of the groundwater (mean sea water level) and standard landfill gas-type monitoring wells should be installed.  These should be fitted with a removable cap and gas monitoring valve so that gas concentrations may be measured as well as flow rates from the open well.

 

It is recommended that two monitoring wells should be installed across the area of the Water Recreation Centre (Figure 6.14b).  These should be located such as to give an approximately even distribution across the whole area.  If they are located within areas designated for open space, it may be possible to retain them for future long-term monitoring.  The wells should be monitored as follows:

·       concentrations of the following gases should be measured using portable monitoring equipment with gas chromatographic (GC) analysis being undertaken on selected samples to confirm the results:

·       methane

·       carbon dioxide

·       oxygen

·       gas flow rates from the open wells - very sensitive techniques (such as micro-anemometer) will need to be used to measure the anticipated very low flow rates. In addition, and if practical, emissions from the surface of the reclaimed land could also be monitored using flux boxes.

 

 

The monitoring schedule will depend on the relative timing of the reclamation and subsequent construction works.  Ideally, the boreholes should be drilled and the monitoring wells installed as soon as possible after the completion of the reclamation works.  Monitoring should then take place over a period of at least one year with the emphasis on the second part of the year.  It will be important to monitor gas flows from the wells under different meteorological conditions and to include some occasions when atmospheric pressure is falling quite quickly (e.g. immediately proceeding a typhoon).

 

Biogas Assessment Protection Measures-General Guidelines

 

At this stage it is difficult to provide precise guidelines on what measures would be required for the specific rates of gas emission which may measured because this would depend on the exact pattern of the results and the design/ purpose of the specific buildings to be erected.  However, the following criteria provide the may be used as general guidelines:

 

Scenario 1

 

If rates of methane emission are consistently much less than the trigger value (10 l m-2 d-1), including monitoring occasions when atmospheric pressure is falling quite quickly, and they do not show any rising trend over time, then the buildings will not require gas protection measures.

 

The trigger value of 10 litres (methane) m-2 d-1 is an "area" emission rate (ie rate at which gas is emitted per unit area of the reclamation).  In order to convert this into an emission rate from a borehole, it is necessary to make an assumption about the "area of influence" of a freely venting borehole which depends on a number of factors - mainly how easy it is for gas to escape from the surface of the site.  Thus, for a site covered in a hard surface (eg paved) it would be expected that any borehole would have a much greater area of influence than if the site had soft landscaping.

 

Different people have assumed different areas of influence - in WMP 26A, it assumed 100 m2 whereas in the South East Kowloon Development Study, the consultant assumed approximately 20 m2 (radius of 2.5m).  To be conservative, it is proposed to adopt an area of influence of 20m2, which would give:

·       Trigger value of 10 l m-2 d-1 x 20 m2  =  200 l d-1 emitted from the borehole

 

In practice, such low rates of gas emission will be measured using 'flux box' methods as the velocity of the gas (m s-1) will be too low to measure, unless very sensitive flow meter is used.  Thus, expressing the flow rate as a volume per day or volume per hour will be acceptable.  Hence, the criterion for safe flow rate from the free venting boreholes becomes:

·       Flow rate of methane (in term of l d-1) < 200 l d-1

OR

·       (Gas flow rate in term of l d-1) x (concentration of methane in gas (in % gas)) <  200 l d-1

 

Scenario 2

 

If the rates of methane emission from any borehole frequently exceed the trigger value or show a rising trend such that future emission rates are likely to exceed the trigger value, then any buildings to be constructed on that part of the site will require some form of gas protection measures.  That is when:

·       (Gas flow rate in term of l d-1) x (concentration of methane in gas (in % gas)) >  200 l d-1

 

The exact details of the gas protection measures would need to be designed to take into account the design and use of the particular buildings involved but would, most probably, include the installation of a low gas permeability membrane in the floor slab of the building.  The exact area of the reclamation over which buildings would need to have gas protection measures would depend on the pattern of the results from the different monitoring boreholes and further investigation may be required to determine the area of land which is affected by gas emissions.  The analysis and assessment of the results and design of any gas protection measures, should be undertaken by suitably qualified and experienced professionals who are familiar with the properties of biogas and the way in which buildings may be protected against the impacts of gases derived from the ground.

 

Scenario 3

 

If there are occasional exceedances of the methane emission rate trigger value or if there is significant fluctuation of the results obtained with some readings coming close to the trigger value, then the exact pattern and any trends in the results will need to be assessed to determine their significance and whether any building protection measures are required.  It might be necessary to undertake additional monitoring by extending the monitoring period, for example, if an apparently spurious high reading is noted towards the end of the monitoring period or if it seems likely that future rates of emission may exceed the trigger value. 

 

Whatever the results obtained from the proposed monitoring of gas emission rates, the analysis and assessment of the results and design of any gas protection measures, should be undertaken by suitably qualified and experienced professionals who are familiar with the properties of biogas and the way in which buildings may be protected against the impacts of gases derived from the ground.

 

Scenario 4

 

If the rates of methane emission from any borehole frequently exceed the Limit value (84.7 l m-2 d-1), or show a rising trend such that future emission rates are likely to exceed the limit value, then no buildings should be constructed on that part of the site. That is when:

 

·       Limit value of 84.7 l m-2 d-1 x 20 m2  =  1,694 l d-1  emitted from the borehole

OR

·       (Gas flow rate in term of l d-1) x (concentration of methane in gas (in % gas)) >  1,694 l d-1

 

Typical /Generic Protection Measures

 

Depending on the results of the monitoring recommended above, it may be necessary (although at this stage it is considered that it is unlikely to be required) to incorporate a number of general protection measures into the design of the redevelopment and to include specific measures in the design of  individual buildings.  Specific details cannot be provided until the results of this monitoring and exact details of individual building designs are available.  A combination of different measures may be used for protecting the development against possible risks due to biogas and discussions would need to be held with the developers and architects to determine which are the most appropriate.

Typical, generic, protection measures which may be employed (depending on the results of the monitoring and exact building designs) include the following:

 

Ventilation of Gas from the Reclaimed Land: Vertical boreholes/wells could be installed across the area of the reclamation to allow gas to vent to atmosphere thereby preventing the build-up of gas pressures within the fill material.  Care would be needed in the design of the venting stacks to ensure that any gas was safely vented without causing nuisance or danger to users of the land.  This technique is probably appropriate only if the monitoring indicates a relatively high rate of gas emission.

 

More specific areas of the development could be targeted such as the footprints of specific buildings or other sensitive areas.  In this case the ventilation measures would be designed specifically to prevent the build up of gas pressure beneath a building, for example, and could comprise a network of horizontal gas collection pipes installed underneath the building connected to a number of risers to allow any accumulated gas to be dispersed to atmosphere at a suitable level above ground.

 

Barriers to Prevent Ingress of Gas into Buildings:  There are a number of ways of ensuring that any gas derived from the ground does not enter a building.  Typically these involve the incorporation of some kind of low gas permeability membrane in the design of the floor and any below ground walls of any ‘at risk’ rooms.  In addition, measures must be taken to avoid or seal any openings in the floor (e.g. at service entry points).  Such techniques are commonly used where there is a risk of landfill gas entering a building and have been employed on a number of developments in Hong Kong.

 

There are various proprietary products which may be used and the specific details of their application will depend very much on the individual building design. 

 

In all cases, extreme care is needed in the installation of the membrane and the other protection measures to ensure that they meet the design requirements and to avoid damage during installation and subsequent construction works.  Adequate QA/QC procedures are therefore essential to ensure that such measures are effective.

 

Ventilation within Buildings:  As an additional or alternative measure for the protection of specific rooms, ventilation (passive or mechanical depending on the circumstances) may be provided to ensure that if any gas enters the room it is dispersed and cannot accumulate in dangerous volumes.  For particularly sensitive rooms, such as below ground confined spaces which contain sources of ignition, forced ventilation may be used in addition to the use of a low permeability membrane whereas for low sensitivity areas ventilation may be used on its own.

 

Protection of Below Ground Services:  As they are installed below ground, conduits in which services (e.g. electricity and other cables) are installed are particularly prone to the ingress and accumulation of gas derived from the ground.  It is therefore important to prevent such conduits acting as easy routes by which gas may enter buildings by avoiding, as far as possible, any penetration of floor slabs by such services or, as a minimum, ensuring that any unavoidable penetrations are carefully sealed using an appropriate low permeability sealant. 

 

In addition, accumulation of gas within any associated manholes or access chambers can present a risk to the staff of the utility companies.  All such companies and organisations which may have cause to work on such below ground infrastructure should be warned of the potential dangers and advised to take appropriate precautions.  Clear warning notices together with contact details for further information and advice should be provided on any access points to below ground chambers.

 

Precautions During Construction

 

Similarly, precautions may be required to ensure that there is no risk due to the accumulation of gas within any temporary structures, such as site offices, during any construction works on the reclamation area.  It may be necessary, for example, to raise such structures slightly off the ground so that any gas emitted from the ground beneath the structure may disperse to atmosphere rather than entering the structure.

 

The exact requirements for precautionary measures during the construction phase would need to be specified following assessment of the results obtained from the monitoring recommended above and the details would depend on the depth of excavation or nature of the voids/structures involved. 

 

Further information and advice, including the precautions required for the drilling of the monitoring boreholes, may be found in the Hong Government’s advisory document Landfill Gas Hazard Assessment Guidance Note prepared by the Environmental Protection Department.

Residual Impact

No residual impact.

No residual impact.

Environmental Acceptability

Acceptable

Acceptable

 

Table 6.15b - Impacts Summary Table for CKWLR

Issue

Construction Impact

Assessment Points

CKLWR Boundary

Relevant Criteria

Waste Disposal Ordinance, Waste Disposal (Chemical Waste) (General) Regulation, Land (Miscellaneous Provisions) Ordinance, Public Health and Municipal Services Ordinance, Dumping at Sea Ordinance, Waste Disposal Plan for Hong Kong, New Disposal Arrangements for Construction Waste, Code of Practice on the Packaging, Labelling and Storage oe Chemical Wastes, EPDTC 1-1-92, WBTC Nos. 6/92, 22/92, 32/92, 2/93, 16/96, 4/98, 5/98, 5/99 and 25/99, and Waste Reduction Framework Plan. 

Potential Impact

Dredged/Excavated Sediment

Dredging of a large quantity of sediment within a short period of time will have the potential to cause adverse water quality impact if not properly managed.  Section 5 has discussed the mitigation measures necessary to avoid adverse water quality impacts during the dredging works. Although the quality of cannot be determined at this stage, based on the sediment quality at Fa Peng and Penny’s Bay Reclamation Stage II, out of the 4.2 M m3 of sediment to be dredged for CKWLR, high contamination in As and Cu is likely to be found at seabed level, and, therefore, biological tests will be required to determine the final disposal route.

For the sediment to be dredged for the Yam O to Penny’s Bay Interchange, which is located at the vicinity of the Cheoy Lee Shipyard, although the volume is minimal (1,300 m3), due to its seriously contaminated nature (Class C), disposal at East Sha Chau Contaminated Mud Pit is required.

 

Use of Public Fill for the Reclamation

 

The CKWLR Phases I and II reclamations will require 8.6 M m3 of fill/surcharge material between Q2 2002 to Q1 2004 and Q4 2026 to Q2 2028 (45 months).  Public fill will be used as fill material and also surcharge material.  The volume of public fill to be used is 7.3 M m3, which is approximately 85% of the total filling/surcharge material required.

The use of public fill as filling material may give rise as floating debris during reclamation.  Part of the all the reclamations will be designated as a public filling area.  Public fill comprising earth, building debris and broken concrete may contain a small amount of floatable materials such as timber, plastic and paper.  If not properly controlled, it may give rise to floating refuse

 

Excavated Material

 

A total of approximately 3.0 M m3 of excavated is expected to be generated from the construction of the CKWLR, primary as a result of excavation at slopes of Pa Tau Kwu.  This figure include the 10,200 m3 of excavated material to be generated from slope excavation for the Yam O to Penny’s Bay Interchange as well as during the excavation at Yam O, Pa Tau Kwu.  Small amounts of excavated material will also expected from the foundation works carried out at CKWLR Phases I and II.  The daily generation rate is 3,000 m3 d-1.

The excavated materials generated at Yam O to Penny’s Bay Interchange and Pa Tau Kwu will consist of clean rock and soil.  Whereas the excavated material generated at CKWLR Phases I and II reclamations will be the same as fill materials used for the reclamation ( ie either marine sand fill or inert public fill).

Excavated material generated at Yam O to Penny’s Bay Interchange could be reused on-site for filling at the Cheoy Lee Shipyard area ([30]).  Whereas excavated material generated at Pa Tau Kwu and CKWLR Phases I and II could be re-used within other NLDFS reclamation such as Penny’s Bay Reclamation Stage II or Theme Park (Phase III) Extension reclamation.  No surplus excavated material will be generated.

As the Penny’s Bay Stage II and Theme Park (Phase III) Extension reclamations require a large quantity of fill material and the Project will have an overall deficit of fill material.  It is anticipated that all the excavated soil and rock generated from the Project will be re-used for the reclamation works.  Since public filling areas only accept public fill with certain size (< 200 mm diameter).  Some of the excavated material may require to be broken prior re-use on site.  No surplus of excavated material will be generated.

 

C&D Waste

 

Although no details on the GFA is available, the structures to be demolished at Ngong Shuen Au and Cheoy Lee Shipyard are considered is likely to be small and simple and the volume of demolition material to be generated is likely to be small.  The potential environmental impacts associated with the decommissioning and demolition of the shipyard is addressed in Section 12 and will be evaluated under a separate Schedule 2 EIA to be commissioned by the CED.

With respect to the demolition works at Ngong Shuen Au and Wan Tuk Village, the volume demolition material to be generated is likely to be minimal and consist of a mixture of inert (ie concrete, tiles, bricks, etc. which are classified as public fill) and putrescible (paper, plastic, wood, etc. which are classified as C&D waste) materials.  The public fill should be reused on site, as far as practicable.  If on-site use is not practicable, the public fill should be delivered to other reclamation sites or to public filling areas available at that time.  The disposal of inert C&D material at public filling areas or other reclamation sites is unlikely to raise any long term concerns because of its inert nature.  Due to small volume of arisings, the disposal of C&D waste at strategic landfills will not cause any unacceptable environmental impacts.

It is not anticipated that there will be any potential hazard associated with handling and disposal of C&D material if general construction safety procedures are properly implemented.

 

Chemical Waste

 

A small volume of chemical waste, such as used lubricating oils from plant maintenance materials, will be produced.  Provided chemical wastes are disposed of at a licensed facility, the contractor should be in compliance with all relevant regulations and there will be little environmental impact.

 

General Refuse

 

The maximum daily number of workers on site is 350.  Based on a waste generation rate of about 0.65 kg per person, it is estimated that the amount of general refuse to be generated will be in the order of 227.5 kg d-1.

Mitigation Measures

The Contractor should development a Waste Management Plan to Engineer approval prior to construction.  Such a management plan should incorporate site specific factors, such as the designation of areas for the segregation and temporary storage of reusable and recyclable materials.

 

Dredged/Excavated Sediment

·       minimising exposure to any contaminated material by the wearing of protective gear such as gloves, providing adequate hygiene and washing facilities, and preventing eating during dredging/excavation;

·       any contaminated sediment dredged should not be allowed to stockpile on the site and should be immediately removed from site once dredged;

·       all vessels for marine transportation of dredged sediment should be fitted with tight fitting seals to their bottom openings to prevent leakage of materials; and

·       loading of barges and hoppers should be controlled to prevent splashing of dredged material to the surrounding water, and barges or hoppers should under no circumstances to be filled to a level which will cause other overflowing of materials or polluted water during loading or transportation.

 

Use of Public Fill for the reclamation

 

The Contractor should enforce strict application of the public fill license and monitor the material placed in the reclamation and barges to control disposal of unauthorised material.  The Contractor shall also provide floating booms and collect any floating materials on a daily basis at the public filling areas.

 

Excavated Material

Wherever practicable, excavated materials should be segregated from other wastes to avoid contamination thereby ensuring acceptability at public filling areas or reclamation sites and avoiding the need for disposal at landfill.  The priority for off-site disposal of surplus excavated material should be as follows:

 

·       transport to other reclamation sites at North Lantau and Penny's Bay areas; and

transport to public filling areas

 

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

 

·       avoidance and minimisation, that is, not generating waste 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 reducing costs.  For example, by reducing or eliminating over-ordering of construction materials, waste is avoided and costs are reduced both in terms of purchasing of raw materials and in disposing of wastes.  Records of quantities of wastes generated, recycled and disposed (locations) should be properly kept.

 

Standard formwork should be used as far as practicable in order to minimise the arisings of C&DM.  The use of more durable formwork or plastic facing for the construction works should be considered during the detailed design.

 

Any uncontaminated soil should be reused on site as far as possible for landscape works in order to minimise the amount public fill to be disposed off-site. Should there be any surplus public fill generated from the project, the HKITP should liaise with the Public Filling Sub-Committee to identify as far as possible suitable reclamation or site formation projects near the project site to reuse the material.

 

The design of the foundation works will minimise the amount of excavated material to be generated.  Should piling be required, H-piling will be used as far as practical.

 

The purchasing of construction materials will be carefully planned in order to avoid over ordering and wastage of construction materials, such as ready mixed concrete.

 

Measures To be Taken in the Construction Stage To Reduce the Generation of C&DM

 

The Contractor should recycle as much as possible of the C&D material on-site.  Public fill and C&D waste should be segregated and stored in different containers or skips to enhance reuse or recycling of materials and their proper disposal.  Concrete and masonry, for example can be crushed and used as fill and steel reinforcing bar can be used by scrap steel mills.  Different` areas of the work sites should be designated for such segregation and storage.

 

At present, Government is developing a charging policy for the disposal of waste to landfill.  When it is implemented, this will provide additional incentive to reduce the volume of waste generated and to ensure proper segregation to allow disposal of inert material to public filling areas.

 

In order to minimise the impacts of the demolition works these wastes must be cleared as quickly as possible after demolition.  The demolition and clearance works should therefore be undertaken simultaneously.

 

Chemical Waste

 

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 that is produced, 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:

 

·       by 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 as chemical waste if necessary); and

·       be arranged so that incompatible materials are adequately separated.

 

Disposal of chemical waste should:

 

·       be via a licensed waste collector; and

·       be 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; or

·       be to a re-user of the waste, under approval from the EPD.

 

The Centre for Environmental Technology operates a Waste Exchange Scheme which can assist in finding receivers or buyers.

 

Management of General Refuse

 

General refuse generated on-site should be stored in enclosed bins or compaction units separate 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.

 

General refuse is generated largely by food service activities on site, so reusable rather than disposable dishware should be used if feasible.  Aluminium cans are often recovered from the waste stream by individual collectors if they are segregated of easily accessible, so separate, labelled bins for their deposit should be provided if feasible.

 

Office wastes can be reduced through recycling of paper if volumes are large enough to warrant collection.  Participation in a local collection scheme should be considered if one is available.  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 5/99 to monitor the disposal of C&DM and solid wastes at public filling facilities and landfills, and to control fly-tipping.  A trip-ticket system will be included as one of the contractual requirements and implemented by the Engineer.  The Engineer should audit the result 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.

Residual Impact

No residual impact.

Environmental Acceptability

Acceptable

 


([1])           "C&D material" refers to surplus materials  arising from any land excavation or formation, civil/building construction, roadwork, 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 of building 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 at landfills.

([2]) EPD Communication red EP20/03/205 M.

([3]) Construction of An International Theme Park in Penny's Bay of North Lantau and Its Essential Associated Infrastructure EIA, for CED, prepared by ERM, February 2000.

([4]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructures, for CED, prepared by ERM, February 2000.

 

([5]) A Study of Tributylin Contamination of Marine Environment of Hong Kong, for EPD, Aspinwall (1998).

([6]) Construction of An International Theme Park in Penny’s Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, prepared by ERM, February 2000.

([7]) Construction and Demolition material (C&D material) contains a mixture of inert and non-inert material.  The inert portion is 'public fill'.  The non-inert portion is 'C&D waste'.

([8]) 4,300 from Penny’s Bay Reclamation, Yam O Reclamation and Theme Park, 1,700 from other NLDFS developments and CKWLR construction.

([9]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, prepared by ERM, February 2000.

([10]) Environmental Resources Management (1999).  Sludge Treatment and Disposal Strategy Study Final Report, 9 July 1999.

([11]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([12]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([13]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([14]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([15]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([16]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([17]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([18]) Environmental Protection Department (1997), Landfill Gas Hazard Assessment Guidance Note.

([19]) Report 152: Risk Assessment for Methane and Other Gases from the Ground, 1995.

([20])    Calculation as follows:

·        0.05ms-1 from borehole = 4,320 m d-1

·        From cross-sectional area of borehole (1.96 x 10-3 m2) = 8.47m3 d-1

·        Assuming that the gas released from the borehole is being collected from an area of ground of, say, 100m2 (radius of influence = 5.6m), then maximum safe rate of emission is:

          8.47/100 m3 CH4 m-2 d-1

     = 0.0847 m3 CH4 m-2 d-1  or  84.7 litre CH4 m-2 d-1

([21])                Shelton David and Tiedje J (1984) General Method for Determining Anaerobic Biodegradation Potential.  Applied and Environmental Microbiology, 47 (7), pp850-857

([22])  Biotal Ltd (1992) further development of Landfill Assessment Methods: The Potential Gas Yield and Gas Production Rate Test.  DoE Report CWM 090/93, September 1992.

([23])  Croft BC and Campbell DJV Assessment of a Test for Biological Methane Potential, DoE Report CWM 103/94, May 1994.

([24]) Testing methods of SOD and TOC are agreed by EPD.

([25]) It is calculated based on the methane generation potential.

([26]) The hydraulic and water quality studies undertaken in 1989 indicated that the siltation rate in Victoria Harbour was only about 500 mm yr-1.

([27]) Remote Survey on Soft Bottom Environments in Coastal Waters of Hong Kong, 1983, Binnie Consultants Ltd.

([28]) Seabed Ecology Studies: Thathong Channel Final Report, 1997, ERM-HK.

(28)"Biogas Risk Assessment" report of Tsuen Wan Bay Further Reclamation and "Potential Methane Gas Risk" report of South East Kowloon, CES (Asia) Ltd.

([29]) Hock, J., (1992).  Effect of leaking natural gas on soil and vegetation in urban areas, Wageningen.

([29]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.

([30]) Construction of An International Theme Park in Penny's Bay of North Lantau and its Essential Associated Infrastructure EIA, for CED, February 2000.