WASTE DISPOSAL PLAN FOR HONG KONG EXECUTIVE SUMMARY
Waste Arisings Hong Kong's waste arisings currently amount to nearly 22,500 tonnes per day (t.p.d.) not including the 49,000 rrr of excavated and dredged materials which are dumped at sea. The main components of these arisings are household waste (approximately 4600 t.p.d.), industrial and commercial wastes (approximately l800 t.p.d.), construction waste (approximately 6500 t.p.d.), livestock waste (approximately 2000 t.p.d.), water works sludges (approximately 4000 t.p.d.) and pulverised fuel ash (approximately 2600 t.p.d.).
Waste Collection Wastes are collected and delivered to disposal sites "by the statutory collection authorities (the Urban Council, the Regional Council and the Director of Environmental Protection), by numerous private waste collection contractors and, in the case of some industrial waste, by "in house" labour. The collection authorities collect and deliver for disposal most household, some commercial and most street wastes, some clinical waste and most excremental waste. The remainder is handled by the private sector. Environmental problems, which are generated by both the public and private sector waste collection systems, include odour, leachate spillage, dust, noise and littering. Existing controls over the operations of private sector waste collectors and transporters are fragmented and ineffective.
Waste Disposal Most wastes are currently either incinerated at one of three government-operated incineration plants or disposed of at one of five government-operated landfills. The old composting plant at Chai Wan now functions as a temporary bulk transfer facility for the transport of publicly-collected waste to landfill. Incineration plants are reserved primarily for the destruction of publicly-collected household wastes. Privately-collected wastes are disposed of at landfills. Dredged and excavated materials are currently dumped at sea whilst most livestock and chemical wastes are hosed down into the nearest water course (livestock waste) or poured down the nearest drain (chemical wastes). Waterworks sludges are currently discharged either to sea or to inland watercourses. Pulverised fuel ash is either recycled as building materials or stored in specially constructed lagoons. Environmental problems at existing lan<±filtis * include inadequate gas and leachate control, and differential settlement. The main environmental caused by incinerators is air pollution* - II -
Future Projections Based on past trends and future projections it is anticipated that daily waste arisings in Hong Kong will continue to increase such that by the year 2001 they will amount to approximately 30,000 t.p.d. This figure includes approximately 5&0 t.p.d. of sewage sludge which will result from planned expansion of the existing sewage treatment capacity and 6550 t.p.d. of waterworks sludge. It also includes 4500 t.p.d. of pulverised fuel ash and furnace bottom ash. However it does not include dredged and excavated materials intended for marine dumping, and wastes diverted for disposal at public dumps.
The Strategy The different types of wastes arising in Hong Kong require different methods of treatment and disposal. These methods are : . (a) Dredged and excavated wastes should continue to be dumped at sea in a controlled fashion. .'•••• - - ^;f (b) Sewage and waterworks sludges arising in areas with easy access to deepwater frontage should be dumped at sea initially on an experimental basis with a view to further extension if this method is found environmentally satisfactory; sewage sludge should be stabilised before Such dumping proceeds; waterworks sludge will require thickening to effect economy of transportation. (c) Waterworks sludges not arising in areas with easy access to deepwater frontage should be discharged to coastal waters down long sea outfalls. This is subject to detailed assessment studies on a case by case basis to ensure that no long term damage to the marine ecosystem is caused. (d) Sewage sludge not arising in areas with easy access to deepwater frontage should be ^ewatered. and disposed of at landfill. (e) Excremental waste should be disposed of at sewage works or in limited quantities at landfill. (f ) Livestock waste collected by the government should be f stabilised and composted _grlor_t9 ^S2S2]^sS£ • As all wastes cannot be dealt with in this way," alternatives which require further consideration are: 1} disposal at landfill after stabilisation; ii) disposal at sea after stabilisation; and iii) disposal at sewage works by digestion with sewage sludge. - Ill -
(g) Abattoir waste should be regrocessed as far as practicable, and the non-r*e^cTe"aSXe fraction should be disposed of at landfill. ( h ) Animal carcas ses should be _des trpyed .j^L—J-L cremator. r'T :l (i) Clinical waste should wherever possible be , .. iji.cinerat. o rs; to cater for the""was'te g^erated at hospitals, doctors f surgeries and clinics where incineration facilities are not available or cannot meet air emission standards a central incinerator should be constructed. (j) Chemical wastes should wherever possible be codisposed at landfill. Those wastes for which this is not possible should be disposed of at a
1 (k) Radioactive waste should be stored, returned to suppliers or otherwise disposed of in accordance with the directions of the Radiation Board. (1) Pulverised fuel ash and furnace bottom ash should be sold for re-use or lagooned; there is also a possibility, requiring further investigation, that the materials could be used for reclamation and land restoration. (m) All other wastes should be disposed of at landfills, if necessary after treatment at existing incinerators or at transfer stations which are being developed (see below).
The Municipal Waste Disposal Strategy The municipal waste disposal strategy is designed to ensure the environmentally acceptable disposal of waste in the 'most cost efficient manner available. Landfills will always be required to dispose of various wastes and the residues from other waste treatment processes (such as Incinerator ash, unuseable construction waste and some chemical wastes) for which there are no acceptable alternative methods of disposal. _Three very large „ landfill_ _ ^ites__are being.. ^,. dey elopj" e d _ in _ remot QT^JBSSAs^. SJL JtJfcijLJi^^ The s e
so a _network_of _ refusei .^ in_t^ r" '_ WasteTjfOT^ or dinary refu^^col .it ^"will^ then, be compacted , containerised and shipjged^ in, ^|)ul|c \\ tos f + the , lan^ril"§. """""TPKe^'ifrrsF ' t wo ' ' * t ransfer^" ¥lta*ibtis'' ' being ^^^^_,_( W^^«L be used principally td handle publicly-collected wastes, but as additional capacity is available, it is intended that transfer stations will also eventually be able to handle privately-coXlected wastes. - IV -
Refuse transfer stations coupled with the new landfills will be a comparatively cheap and undoubtedly more environmentally acceptable disposal option than maintaining the existingr* municipal v> incinerators. Environmental problems caused by the incinerators are exacerbated by the fact that they are located in densely populated urban areas. As alternative treatment and disposal facilities become available, these incinerators will therefore be phased out. Any new incinerator that may in future be developed will have to incorporate highly sophisticated pollution control equipment allied to a waste segregation and recycling facility, and they would be located in remote areas.
N
NEW TERRITORIES UEN MUN TSUEN WAN
ROAD TRANSFER BARGETRANSFER © LANDFILL TRANSFER STATION
The strategy for the management of municipal waste - V -
Livestock & Chemical Waste Control In order to treat livestock manure collected under the waste control programme a number of waste consolidation/composting plants are planned at various locations in the New Territories. A chemical waste treatment centre is also planned at Tsing Yi to tie in with a new regulatory programme for chemical waste disposal.
Tentative Programme Working to a planning horizon of 2001 and subject to the availability of resources the programme for the development of new facilities and the closure of old ones is : Year Event 1989 • Lai Chi Kok incinerator Station B closed down upon recommissioning of Station A 1990 . Expansion of composting plant at Ngau Tarn Mel to 25 t.p.d* capacity Refuse transfer station commissioned in Kowloon Bay Lai Chi Kok incinerator Station A and Jordan Valley landfill closed when Kowloon Bay transfer station commissioned 1991 * Chai Wan pulverisation plant closed - 92 down Livestock waste consolidation site commissioned at Site A in north east New Territories Livestock waste consolidation site commissioned in south west New Territories Sludge disposal facility commissioned at Sha Tin for marine dumping Chemical waste treatment centre incorporating a Marpol reception facility commissioned at Tsing Yi WENT landfill commissioned Island East transfer station commissioned In Chai Wan -.-... Kennedy Town incinerator closed down Pillar Point Valley landfill closed VI -
Year Event 1993 . Shuen Wan landfill closed upon - 94 commissioning of NENT landfill Island West transfer station commissioned in Western district Transfer station commissioned in Yuen Long/Tuen Mun Transfer station commissioned in Sha Tin Livestock waste consolidation site commissioned in north west New Territories Livestock waste consolidation site commissioned at Site B in north east New Territories Junk Bay landfill closed upon commissioning of SENT landfill Centralised incineration facility for clinical waste and animal carcasses commissioned. 1995 • Transfer stations commissioned in West Kowloon, Tai Po and possibly 2001 North Point . Livestock waste consolidation site commissioned in south east New Territories Livestock waste consolidation site commissioned in the Islands District The Kwai Chung incinerator will be closed down after the Kowloon West transfer station is commissioned.
Legislative Control •'•'••Acceptable environmental standards must be applied to both collection systems and waste treatment and disposal facilities. A licensing system will be established as part of a scheme of control for the collection and transportation of chemical and difficult wastes. The feasibility of establishing a licensing system for the control of the private collection of household and commercial wastes will also be studied. To ensure waste treatment and disposal facilities are operated to an acceptable environmental standard, full use must be made of the licensing provisions of section 16 of the Waste Disposal Ordinance (Cap. 35^) which must be amended to bring within its ambit facilities operated by government departments. TABLE OF CONTENTS
Page No,
1. INTRODUCTION 1
2. PLANNING OBJECTIVES AND THE SCOPE 3
BACKGROUND 3 PLANNING OBJECTIVES 3 PLANNING HORIZON AND THE SCOPE 4
INSTITUTIONAL ARRANGEMENTS AND FACILITIES FOR THE COLLECTION AND DISPOSAL OF WASTE 5
DIVISION OF RESPONSIBILITIES 5 WASTE COLLECTION 5 COLLECTION AUTHORITIES 5 PRIVATE SECTOR 13 WASTE TREATMENT AND DISPOSAL 14 FINAL DISPOSAL FACILITIES 19 TREATMENT FACILITIES-INCINERATORS & TEMPORARY TRANSFER 20 FACILITY MARINE DUMPING FACILITY 23 CO-DISPOSAL FACILITY 25 RADIOACTIVE WASTE DISPOSAL 26 PFA AND FBA DISPOSAL 26
4. PROPOSALS FOR IMPROVEMENT OF EXISTING ARRANGEMENTS 29
BACKGROUND 29 WASTE COLLECTION 29 Household and commercial wastes 29 (a) Public sector 29 (b) Private sector 31 Industrial and construction wastes 32 Clinical waste 33 Other -wastes 33
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WASTE DISPOSAL 34 Landfill 34 Incinerators and temporary transfer facility 38 Codisposal facility 39 Legislative controls 40
5. WASTE DISPOSAL STRATEGY 43
SOLID MUNICIPAL WASTES 43 Final disposal sites 45 Strategy evaluation to arrive at a least-cost plan for waste disposal 49 Programme 51 CONSTRUCTION WASTES 54 DREDGED AND EXCAVATED WASTES 55 DIFFICULT WASTE 56 Sewage sludge and water works sludge 56 Livestock waste 59 Animal carcasses 60 CLINICAL WASTE 60 CHEMICAL WASTE 60 RADIOACTIVE WASTE 62 PFA & FBA 62 SUMMARY OF THE STRATEGY 63
6* THE WAY FORWARD 65
PLANNING BEYOND 2001 65 THE OPPORTUNITY TO MINIMIZE WASTE GENERATION 65 x THE OPPORTUNITY TO PROMOTE RESOURCE RECOVERY 66 v""" *"**llll-li"*l"l'—"™"*glll""'l*l™ll*—""^^ THE ROLE OF THE PRIVATE SECTOR 68 CHARGING POLICY 68 LEGISLATIVE CONTROL 69
- ii - LIST OF APPENDICES
Page No,
APPENDIX A TYPES AND QUANTITIES OF CURRENT WASTE ARISINGS Al
WASTE TYPES Al Household waste Al Street waste Al Marine collected waste Al C omme r c1a1 w a ste A3 Industrial waste A3 Construction waste A3 Dredged and excavated wastes A3 Difficult waste A4 Chemical waste A5 Clinical waste A5 Radioactive waste A5 Pulverised fuel ash (PFA) and furnance bottom ash (FBA) A6 Secondary wastes A6 CURRENT WASTE ARISINGS A6 COMPOSITION OF HOUSEHOLD WASTE A7 GEOGRAPHICAL DISTRIBUTION OF WASTE ARISINGS DELIVERED TO LAND-BASED FACILITIES All EXTENT OF WASTE RECYCLING All
APPENDIX B PROJECTED FUTUEE WASTE ARISINGS Bl
PUBLICLY-COLLECTED WASTE Bl PRIVATELY-COLLECTED MIXED WASTE Bl CONSTRUCTION WASTE B3 DREDGED AND EXCAVATED WASTES B3 DIFFICULT WASTE B3 Sewage sludge B3 Water works sludge B5 Sewage works screenings B6 'Excrementa1 waste B6
- lii - Page No,
Livestock wastes B6 Animal carcasses B9 Abattoir waste B9 Condemned food B9 CHEMICAL WASTE B9 CLINICAL WASTE Bll RADIOACTIVE WASTE fill PULVERISED FUEL ASH (PFA) AND FURNACE BOTTOM ASH (FBA) Bll PROJECTED TOTAL DISPOSAL REQUIREMENTSFOR MUNICIPAL WASTE B13 CONTROL TOTAL FOR MUNICIPAL WASTE B13 GEOGRAPHICAL DISTRIBUTION OF FUTURE WASTE ARISINGS B16
APPENDIX C ENVIRONMENTAL PROBLEMS Cl
ENVIRONMENTAL PROBLEMS POSED BY EXISTING COLLECTION ARRANGEMENTS Cl ENVIRONMENTAL PROBLEMS ASSOCIATED WITH WASTE TREATMENT AND DISPOSAL FACILITIES C3 Landfills C3 (a) Odour G3 (b) Gas C3 (c) Leachate C4 (d) Differential settlement C5 Municipal incinerators C5 Chai Wan pulverisation plant C6
APPENDIX D EVALUATION OF ALTERNATIVE DISPOSAL OPTIONS Dl
MUNICIPAL WASTES Dl Treatment Methods Dl (a) Resource recovery Dl (b) Incineration D3 (c) Transfer D5
- iv - Page No,
Disposal Methods D7 (a) Landfill D7 (b) Dumping at sea D7 (c) Discharge to coastal waters D8 DIFFICULT WASTES D8 Sewagesludge D9 Water works sludge DIG Sewage treatment works screenings and grit DIG Excrementa1 waste Dll Livestock waste Dll Condemned goods,abattoir waste and animal carcasses D12 OTHER WASTES D13 Dredged and excavatedwastes D13 Clinical waste D13 Chemica1 wa s t e D14 Radioactive waste D15 PFA and FBA D15
APPENDIX E THE WASTE MANAGEMENT MODEL (WMM) El
APPENDIX F ESTIMATED CAPITAL AND RECUREENT Fl COSTS OF PROPOSED MAJOR WASTE MANAGEMENT FACILITIES LIST OF TABLES
Page No,
Table 1 Waste intake (t.p.d.) at treatment and disposal facilities in 1988 17
Table 2 Operating characteristics of existing and firm-planned final disposal facilities 20
Table 3 Operating characteristics of existing waste treatment facilities 21
Table 4 Capacities and calculated life times of 11 potential strategic landfills and two potential incinerators 45
Table A.I Estimated arisings of waste types in 1988 (tonnes/day unless otherwise indicated) A2
Table A.2 Estimated Current Arisings of Chemical Wastes in Hong Kong in 1988 A8
Table A,3 Export of Waste Materials (From 1986 to 1988) A14
Table B*l Projected future arisings of sewage sludge (tonnes per day) B5
Table B*2 Projected future arisings of water works sludge (tonnes per day) B5
Table B.3 Projected future arisings of septic tank sludge (tonnes per day; 47* d.s.) B6
Table B*4 Projected future arisings of livestock wastes requiring collection and disposal (tonnes per day; 15% d,s*) B8
Table B*5 Projected Arisings of Chemical Waste in 1992 &. 1997 (Units in tpa) BIO
- vi LIST OF FIGURES
Page No«
Fig. 1 Municipal waste arisings, processing and disposal flow for 1988 6
Fig. 2 Location of existing waste treatment and disposal facilities 15
Fig. 3 Location of spoil grounds for dumping of dredged materials 24
Fig. 4 Quantities of waste by category in 1988 and estimates for 2001 44
Fig. 5 Potential future solid waste disposal facilities in Hong Kong under consideration in 1983 study 46
Fig. 6 Proposed location of future refuse transfer stations and strategic landfills 52
Fig. 7 Location of proposed sludge dumping ground 57
Fig. 8 Location of proposed chemical waste treatment plant 61
Fig. A.I Waste Composition - Waste Collected in Urban Area and New Territories 1988 A9
Fig. A.2 Composition of domestic solid waste in a number of cities A10
Fig. A.3 Boundaries of waste arisings districts in Hong Kong A12
Fig. A.4 Distribution of 1988 waste arisings by district A13
Fig. B.I Forecast of publicly collectd waste B2
Fig. B.2 Forecast of privately collected waste B2
Fig. B.3 Forecast of construction waste B4
Fig. B.4 Quantities of dredged and excavated material dumped between 1978 and 1988 inclusive B4
Fig. B.5 Projected total arisings of PFA and FBA B12
• '-. :-'"-: •-• - - - - vii ~ •' - '• ' '' '. ' :: Page No,
Fig. B*6 The combined annual arisings of waste as a function of GDP B14
Fig. B.7 Forecast of municipal waste arisings based B15 on GDP growth
Fig, B,8 Projected future waste arisings by region and by type B17
- viii - LIST OF PLATES
Page No,
Plate 1 Waste disposal operation at Junk Bay landfill 16
Plate 2 Excavated material loaded onto a barge for 24 delivery to reclamation sites. Only unsuitable materials are disposed of by marine dumping
Plate 3 Lagoon used for the storage of PFA slurry at 27 Tsang Tsui, West New Territories
Plate 4 Unloading of refuse from plastic wheeled bins 30 (equipped with self closing lids) into a refuse collection vehicle
Plate 5 Automatic washing station at a refuse collection 30 vehicle depot
Plate 6 Landfill gas monitoring at a purpose-built borehole 35
Plate 7 A low-rise building structure erected at the Gin 37 Drinkers1 Bay landfill which is being restored in phases for passive recreation uses
Plate 8 Lai Chi Kok incinerator is scheduled to be closed 38 down upon the full commissioning of Kowloon Bay transfer station in April 1990
Plate 9 Delivery of properly packaged asbestos waste to 39 Junk Bay landfill for codisposal with municipal waste
Plate 10 Artist's impression of the layout of Kowloon Bay 53 transfer station
Plate 11 Schematic diagram of refuse transfer operation 53
Plate 12 Construction waste contains much useful materials 55 such as timber and wood waste which should be segregated at source for reuse and recycling
Plate 13 Codisposal of dewatered sewage sludge at Shuen Wan 58 landfill
Plate 14 Collection of dry muck-out livestock waste at the 59 livestock waste collection point
Plate 15 PFA land reclamation trial at Siu Lang Shui 62
Plate 16 Baled waste paper intended for export to the 66 neighbouring South-east Asian Countries
- ix - - 1 -
CHAPTER 1 INTRODUCTION
The Waste Disposal Ordinance (Cap 354) requires the policy Secretary, currently the Secretary for Planning, Environment and Lands to prepare draft plans showing
a) the arrangements made or proposed to be made for the collection and disposal of
i) all solid and semi-solid wastes other than those which may be discharged into the atmosphere as particulates or discharged into water as solids suspended in effluents; and
ii) such other wastes, or classes of waste, as may be prescribed; and
b) all existing and proposed waste .disposal sites and the methods of waste disposal used or to be used at each site.
2* In preparing this plan the Secretary consulted the Environmental Pollution Advisory Committee, the Urban Council and the Regional Council. The draft plan was published for public comment between 4 August and 18 September 1989,
3. The Governor in Council approved the plan on 12 December 1989.
CHAPTER 2 PLANNING OBJECTIVES AND THE SCOPE
BACKGROUND /
4. .Hong Kong is a rapdern c1 tywith a j>opu 1 ati onof 5.7 million, and has nearly two hundredthousandcommercialand industrial establishments. Their daily activities generate a substantial amount of municipal waste* togetherwith the booming cons true t ion and reel araat ion act i yi ty, /I iye s. tock_ ...faralng_in_ the rura 1 areas» power generation and water and/waj5t_ewater treatment operations, the total daily arisings of all kinds of waste amount to nearly 88 thousand tonnes, around three-quarter of which is dredged and excavated material associated with dredging and reclamation activity (Appendix A)* The management of this large quantity of wastes requires proper planning to ensure that there are adequate collection and disposal arrangements, as well as to avoid adverse environmental and public health consequences.
PLANNING OBJECTIVES
5. The principal objective of this plan, as specified in Part II of the Waste Disposal Ordinance, is to describe the arrangements made or proposed to be made for the collection and disposal of all wastes falling within the ambit of the Ordinance, and to give details of all existing and proposed waste disposal sites and disposal methods* In doing this, consideration must be given not only to the Government^ role in waste collection and disposal, but also to those of -
(a) the Municipal Councils. These are by statute autonomous. As waste collection authorities, they provide the great majority of public waste collection services, and any plans must enable them to provide such services in an efficient and environmentally acceptable manner; and (b) the private sector, which already provides a significant variety of waste collection and disposal services. As with the Municipal Councils, the private sector should be able to develop efficient and environmentally acceptable services.
PLAHNIHG HORIZON AND THE SCOPE
6. The planning horizon for this plan is 2001* The emphasis is on arrangements for the collection and disposal of household, commercial and industrial wastes, and the need to provide these essential services in the face of the changing demands imposed by the development of the community. The implementation of this plan is subject to the availability of financial and manpower resources* CHAPTER 3 INSTITUTIONAL ARRANGEMENTS AND FACILITIES FOR THE COLLECTION AND DISPOSAL OF WASTE
DIVISION OF RESPONSIBILITIES
7. As defined in the Waste Disposal Ordinance, the collection authorities are the Urban Council and the Director of Environmental Protection (DEP) in respect of the Urban Council area, and the Regional Council and DEP in the Regional Council area. DEP is also defined as the waste disposal authority for all classes of waste. In discharging their duties and functions, the collection authorities and the waste disposal authority are required to have regard to the waste disposal plan.
WASTE COLLECTION
8. The collection of the bulk of Hong Kong's waste is carried out either by the collection authorities or by private waste collection and disposal contractors. Private waste collection and disposal contractors provide a service completely independent of the publicly-funded collection authorities wherever markets for such services exist . They are also frequently engaged by government departments to remove specific types of waste from facilities operated by those departments* In some instances departments themselves remove and dispose of wastes generated at facilities under their control. Fig. 1 summarises the existing arrangement for the collection and disposal of various types of waste. A more detailed consideration of the arrangements for the collection of wastes is best considered on an agency-by-agency rather than a type-by-type basis.
COLLECTION AUTHORITIES
•9V " The majority of the waste collected jy_tlie_J[Irb_an. Council * jjoljits (RCPs) under ^the^Lr control. There are 309 RCPs in Hong Kong and Kowloon and approximately 1970 in the New Territories operated by the two Councils. 6 -
PULVERISATION 4S. Pulverised PLANT Wastes
PUBLICLY COLLECTED WASTE Ash
(4033 tpd)
PRIVATELY COLLECTED WASTE
(2373tpd) MUNICIPAL V V WASTE 82% LANDFILL 13187 tpd
Site
CONSTRUCTION WASTE
(6521 tpd)
Sewage Sludge & Sewage
ZDIFFICULT + MARINE Works Screenings COLLECTED WASTE (260 tpd) Excrements!
Others
Note: This figure only shows those wastes which are collected for disposal at the municipal waste disposal facilities (i.e. municipal incinerators, pulverisation plant'"or landfills).
Figure 1 Municipal waste arisings, collection and disposal flow for 1988 Of the 309 RCPs in Hong Kong and Kowloon, 80 are within permanent, purpose-built off-street buildings, 37 are temporary off-street structures and 192 are ^temporary _on-_street: flimsy encJLpjsures. Of the 1970 in the New Territories and outlying islands approximately 650 are permanent, off-street structures and the remaining 1320 are temporary off-street structures. Permanent RGPs are purpose-built structures incorporating where ^§J2££oj?x^ extract io^ facilities. As suitable sites cannot always be made available by the Government, temporary RCP's have to be provided for the convenience of the public to deposit their refuse pending collection by the Municipal Councils.
10. Broadly speaking, in areas where RCPs have been located, no kerbside or door-to-door collection service is provided. Instead local residents are required to deliver their wastes to the RCP nearest to them to await collection by one of the refuse collection vehicles (RCVs) operated by the executive arms of the two Councils (ie: the Urban Services Department (USD) and the Regional Services Department (RSD)). Permanent off-street RCPs are provided where appropriate with an attendant and waste may be delivered to the RCP within specified operating hours. The attendant is authorized to reject waste not suitable for collection at a RCP. This system is adopted to ensure that the wastes deposited are acceptable.
11. The majority of the wastes delivered to RCPs for collection is household waste. However in the urban areas a sizeable proportion of the waste may be classified as commercial as it is waste from nearby shops, stalls, restaurants and offices. Such commercial waste is accepted at a RCP provided it does not amount to more than 100 litres per day from each establishment. Amongst the household waste delivered to RCPs is junk and bulky waste. Such wastes are only accepted at major RCPs. 12. All RCPs are visited at least once a .day by a RCV, wh ich piies a pr e de te,rmine d route according__to a Jixed schedule_. When the vehicle is full the waste is hauled directly to a waste treatment or disposal facility* J&CVs^range in size from 3 to 12 tonnes capacity and virtually all are JLapaJxLe. of compacting refuse as it is collected. Volume reduction achieved by compaction ranges from 67% to 80%. Compaction capability usually extends to an ability to crush and compact bulky household items such as furniture. Wherever possible these items will be collected during the course of a normal collection round. For bulky items that cannot be crushed (eg. domestic electrical appliances such as fridges) a special collection round has to be made with lorries*
13. Although collection from RCPs is the main mode of collect-ion of household wastes by USD and RSD there are some variations. In the Urban Council area, in areas of low density housing, or in areas where it has not proved possible to locate an RCP, a kerbside collection service is operated. Householders need only deliver their waste in plastic bags to the kerbside from where they are subsequently collected by a RCV at a predetermined time. In the rural districts of the Regional Council area where the provision of a properly constructed RCP is not justified, householders in the area need only deliver their wastes in plastic bags to the refuse bins provided at selected locations where the wastes are subsequently collected by a RCV or the RSD special cleansing gang. In both the Urban Council and Regional Council areas a block-to-block service is provided within the curtilage of institutions and building complexes constructed by both the public and private sector.
14. In addition to collecting waste from RCPs and housing blocks, the USD/RSD also collects wastes from individual building developments in accordance with the provisions laid down in the Public Cleansing & Prevention of Nuisances Bylaws (Cap 132) by agreement with the owner of the property and subject to such terms and conditions as the two councils may think fit. The Building (Refuse Storage Chambers and Chutes) Regulations 1984 stipulate, among other things, the mandatory provision of refuse storage chambers in new buildings (other than car parks, industrial buildings, schools and churches) with an aggregate usable floor space 2 of 1320M or more and the provision of vehicular access to a public 2 RCV if the aggregate usable floor space is 13,200M or more in the case of domestic and composite buildings. The corresponding criteria for non-domestic buildings are 3960M and 39,600M respectively. The UC was instrumental in introducing these regulations, which effectively stopped the then ever-growing demand for more on-street RCPs as building developers thereafter were to provide adequate refuse storage space and vehicular access for public RCVs to collect refuse within the curtilage of new building developments.
15* Special arrangements are made for the collection of wastes on the outlying islands. On Lantau, in areas where there are vehicular access roads, wastes which are delivered by householders in plastic bags to RCPs and bin sites are collected by lorries, and most of the waste is disposed of at the modular incinerator at Mui Wo. The remaining wastes together with the bulky household items and incinerator ashes are taken by a contracted barge service which also transports refuse from Cheung Chau and Discovery Bay. The household waste is taken to Kwai Chung incinerator and the bulky items are taken to Pillar Point Valley landfill. A similar barge service is also provided for Lamma and Peng Chau Islands. In isolated villages on the islands, waste is presently disposed of by means of village type incinerators which will be gradually phased out and replaced by properly designed package type incinerators or by suitable collection arrangements to the mainland.
16. In addition to the collection of household and commercial waste as described above, the Urban Council and Regional Council also provide services for the collection of
(/ Ca) street waste and litter, including beach litter; ,{/.''J(b)- carcasses of dead animals; excremental waste; and (d) clinical waste. - 10 -
°r mechanica 1 ly ) , empty Utter bins , and ^coUec^J-ltjt^^ sweepings and litter are delivered to the nearest refuse collection point and subsequently removed, along with other wastes deposited there, by RCV and other transport. At those beaches where vehicular access is difficult, the collected litter is disposed of either by on-site burning or by burning in village type
incinerators. The litter collected from country parks: Jb j _the J^sheries D§2artment:_ is also deliyejredjto^^^
_RCP; for ^sub^eflugnt jrjsmoya 1 by RCV, or to a barging point for subsequent removal by a contract barge service.
18. The carcasses of dead dogs and cats left on the streets are a special form of street waste. Animal carcasses, including dead pigs and poultry, are collected by special USD or RSD removal gangs using vehicles with a self-contained, steel-lined, rear compartment allowing complete separation of the carcasses from the crew in the driver's cab. They are then taken directly to a disposal facility.
19. The Urban Council and Regional Council provide collection services for the following types of excrement a 1 waste -
(/ Oa) nightsoil; and septic tank sludges. - ' ' ' ' '
20. A free nightsoil collection service is provided to premises which have no flushing toilets. Most collection is carried out manually but if vehicular access is possible mechanical collection can be achieved using purpose-built tanker vehicles. - 11 -
21. Pneumatic desludging of household septic tanks is carried out on request but, unlike nightsoil, the service is not free of charge. Charges are set to recover the cost of the service and the latter is provided subject to the availability of vehicles and manpower. Desludging of septic tanks installed at government buildings (eg. public toilets) is carried out by USD and RSD. Desludging of a few, large tanks (Imhoff tanks) is carried out by the Electrical and Mechanical Services Department. Many private households also rely on private contractors for desludging of septic tanks.
22. A service for the collection of clinical waste is provided by the Urban Council to those medical institutions which either do not possess their own disposal facilities (usually in the form of incinerators) or whose facilities are inadequate to the task. The service is provided to both private and government establishments. Most types of waste are collected and stored in black plastic bags prior to removal to a designated collection point within the institution. /Sharp objects such as syringe needles and scalpels are first placed in cartons to reduce the danger of perforation of the -N, bags and subsequent injury to personnel^.) The waste is collected in a van similar to that used for animal carcasses and transported to a disposal facility./ Amputated limbs and excised organs are placed in boxes and collected in a special Mcemetary van11 prior to placement in coffins and final disposal at Cape Collinson crematorium and the Diamond Hill Crematorium. ;; 4 l
23. Notwithstanding the provision of a special collection service some types of clinical waste are also mixed with ordinary refuse and collected and removed during the normal USD or RSD refuse collection* A 1982 survey of 74 government and private hospitals and clinics revealed that( 15% of general ward waste was collected by the special collection service but a similar amount of the same waste was collected during the ordinary collection round. ) For theatre and laboratory wastes the figures were 1270 collected by the special collection service and 5% collected with ordinary refuse. - 12 -
For maternity wastes the corresponding figures were 30% and 19% respectively. Even amongst government hospitals there appears to be a lack of consistency in the way the wastes are dealt with. For example at Queen Mary Hospital, Tang Shiu Kin Hospital and Tsan Yuk Hospital contaminated waste from treatment areas is removed by the special collection service. Queen Mary Hospital and Tsan Yuk Hospital also use the special collection service for the removal of certain pharmaceutical and chemical wastes, but Kowloon Hospital and Queen Elizabeth Hospital get rid of this waste via the normal refuse collection service.
24, The survey of government and private hospitals and clinics referred to above did not cover private doctors1 clinics and surgeries. Waste generated at these clinics and surgeries is not collected by a special collection service and inevitably finds its >-•••.•' into £he ordinary cammer'cial refuse.
25. A limited collection service is provided for livestock wastes through contractors employed by the Environmental Protection Department. The collection service is intended mainly for the collection of manure from dry muck-out and sludge arising from treatment of wet muck out waste. Each collection point will consist of a number of drums into which waste may be deposited.
26. The service is provided initially in the first few livestock waste control areas such as the Tolo Harbour and Tolo Channel Area and this will be. extended to tie in with the phased implementation of the regulatory controls so that all livestock farms have access to a collection point. Where road access is poor the roads in question will be upgraded. Initially the waste will be collected by a government contractor employed by the Environmental Protection Department and delivered either to a landfill site or a composting plant for disposal or treatment respectively.* - 13 -
The cost of the collection service will initially be met by the government but the subsidy will gradually be phased out so that it is eventually borne by the farmers. It is possible that this will lead to the eventual replacement of the government service by collection arrangements organised by the farmers themselves.
PRIVATE SECTOR
27. Private waste collection and disposal enterprises in Hong Kong are many and diverse. They range from individuals engaged by householders in multi-storey buildings to collect refuse daily and ° deliver it to RCPs, to large modern waste disposal contractors who collect industrial waste and deliver it to a final disposal point.
28. The private waste collection and disposal enterprises deal with most types of waste generated in Hong Kong. Industrial wastes, construction wastes, certain chemical wastes, pulverised fuel ash, and condemned food are handled exclusively by the private sector. Substantial amounts of commercial wastes are also collected by the private sector. Household waste is collected mainly from those private developments which do not have facilities and vehicular access of the standard required by the collection authorities but for which it would be impractical to send waste to a RCP.
29. Due to the diversity within the private sector it is impossible toj^nerali^ transportation arrangements. Such arrangements are in any case worked out by contracting parties. Suffice to say that a wide variety of collection vehicles is employed, ranging from hand trolleys onto which are loaded open baskets of waste, through general purpose vai«s and trucks to purpose-built RCVs and tankers. Except in the case of certain special types of waste (specifically certain categories of dangerous goods defined in the Dangerous Goods Ordinance, Cap 295) - 14 -
and notwithstanding provisions in the Public Cleansing and Prevention of Nuisances Bylaws (Cap 132) which do offer some scope for control, collection and transportation equipment and practices are seldomly controlled. A measure of control is imposed in respect of those specific collection services that the government contracts for. These include the collection of sewage screenings and grit, sludges from Imhoff tanks at government facilities, and secondary wastes. Sewage works screenings and grit from screening plants operated by the Electrical and Mechanical Services Department (EMSD) are collected in 200 litre covered drums and removed by a contractor on a flat bed lorry. Imhoff tanks in some government facilities are desludged by EMSD and the sludge is also placed in 200 litre covered drums which are removed on a flat-bed lorry by a private contractor. Of the secondary wastes which comprise incinerator ash and pulverised waste, incinerator ash is removed by EMSD in dumper trucks whereas pulverised waste is removed from the Chai Wan pulverisation plant by a contract barge service.
WASTE TREATMENT AND DISPOSAL
30. Excluding marine dumping sites there are nine major facilities operated or controlled by the government at which waste is treated or disposed of. These comprise five landfills, three incinerators, and one temporary transfer facility (Chai Wan pulverisation plant). Regionally, they are distributed as follows• :-
Hong Kong Island Kennedy Town Incinerator Chai Wan Pulverisation Plant
•'•Kowlooii Lai Chi Kok Incinerator Jordan Valley Landfill
New Territories Kwai Chung Incinerator Junk Bay Stages I & II Landfills Shuen Wan Landfill Pillar Point Valley Landfill
The locations of these facilities are illustrated in Figure 2. - 15 -
GUANGDONG SHENG N
JUNK BAY STAGE I JUNK BAY STAGE
LEGEND: A LANDFILL • INCINERATOR • PULVERISATION PLANT
Figure 2 Location of existing waste treatment and disposal facilities
31, A small modular incinerator (theoretical capacity 12 t.p.d.) at Mui Wo on Lantau Island is operated by EMSD to deal with domestic refuse. A number of village-type incinerators are operated by RSD in remote villages at the outlying islands for the destruction of refuse* A new package type incinerator is also operated by RSD at Kat 0 in North District. Other small incinerators are located at hospitals for the destruction of clinical wastes, and at the Urban Council abattoirs for the destruction of diseased animal remains. The hospital and abattoir incinerators are designed for longer waste residence times than municipal incinerators to ensure that complete destruction of all combustible material is achieved. - 16 -
Plate 1. Waste disposal operation at Junk Bay Landfill
32r. Most wastes are currently disposed of or treated at one of the above nine major facilities. The manner in which wastes were distributed amongst the different facilities in 1988, by broad type and collecting agency, is set out in Table 1. The three incinerators, Chai Wan pulverisation plant and Jordan Valley landfill mainly receive waste collected by the collection authorities, the bulk of which is household waste. Around six per cent of the waste delivered to Kennedy Town and Lai Chi Kok incinerators is waste of a commercial nature delivered by the private sector. Such deliveries are made under a permit system. The purpose is to provide these incinerators with a certain quantity of high calorific value waste which, when mixed with domestic waste, helps produce a better burn and thereby increases operating efficiency. For Kwai Chung incinerator the intake of commercial waste is unnecessary. - 17 -
Table 1. Waste intake (t.p*d.) at treatment and disposal facilities in 1988
Waste ^•Publicly Privately-collected Publicly-collected or Total Facility collected collected under contract Industrial, Construc- Difficult Inciner- Pulverised Commercial, tion clinical ator ash waste Household and marine
Kennedy Town 500 76 576 0x incinerator Lai Chi Kok 443 22 465 incinerator Kwai Chung 861 861 , incinerator Chai Wan 490 490 pulverisation plant Pillar Point 375 425 960 28 208 1996 Valley landfill Shuen Wan 419 253 1157 125 1954 landfill Junk Bay Stage I 245 1520 4019 106 262 374 6526 5 landfill Junk Bay Stage 1747 2373 130 4250 II landfill Jordan Valley 700 10 294 1 1005 landfill
Collected by USD and RSD; mainly household waste but including some commercial and street waste.
Includes sewage screenings and sludge, excremental waste, condemned food, abattoir waste, clinical waste, and marine collected waste*
Plant A closed temporarily from Feb 1987 to Mar 1989 for retro-fitting with electrostatic precipitators and hence the intake has reduced.
Chai Wan pulverisation plant was originally a composting plant which ceased to produce compost in August 1987. It is now used as a temporary transfer facility. The total intake also includes waste by-passing the plant and directly off-loaded for barge transfer to Junk Bay landfill.
Junk Bay Stage II landfill commenced operation for a short period of 2 weeks towards the end of 1988, and the waste intake figures relate to this period . -. 18 -
33. The pattern of delivery of publicly-collected waste to the incinerators, the pulverisation plant, and Jordan Valley landfill is based primarily on the need to keep the transportation costs of the collection authorities as low as possible. Thus Chai Wan pulverisation plant receives the bulk of its intake from Eastern district and Wan Chai whereas the main intakes for Kennedy Town incinerator are from Central & Western and Southern districts. Similarly in Kowloon, Lai Chi Kok incinerator obtains the bulk of its intake from Kwun Tong, Wong Tai Sin, Kowloon City and Tsim Sha Tsui. Kwai Chung incinerator takes large quantities from Kwai Chung and Tsuen Wan, and it also takes substantial amounts from Sham Shui Po, Mong Kok and Tsim Sha Tsui. The bulk of the publicly- collected waste delivered to Jordan Valley landfill originates in Kwun Tong but substantial quantities also come from every other district in Kowloon.
34. As far as publicly-collected wastes are concerned the remaining facilities are strategically located and serve easily identified catchment areas in the New Territories. Thus Shuen Wan landfill serves the north east New Territories and receives publicly-collected waste arising in Sha Tin, Tai Po and North districts. Pillar Point Valley landfill serves the western New Territories and receives almost all its publicly-collected waste from Tuen Mun and Yuen Long-* Junk Bay landfill (Stages I & II) serves the south east New Territories and receives the majority of its publicly- collected waste from Sai Kung.
35* Over 95% of all the waste collected by the private sector is delivered to the four landfills in the New Territories* Junk Bay landfill (Stages 1 & II) is the main destination for privately-collected waste arising in Hong Kong and Kowloon but both Shuen Wan and Pillar Point Valley take in small quantities from these regions. Privately-collected wastes arising in the New Territories - 19 -
are distributed to landfills mainly according to the catchment areas in which they arise, but in addition to taking waste arising in the south-east New Territories Junk Bay landfill (Stages I & II) also receives a substantial amount of its privately- collected wastes from Kwai Chung and Tsuen ¥an.
FINAL DISPOSAL FACILITIES
36. The final disposal facilities are the landfills. They are operated by private contractors under the control of the Civil Engineering Services Department* ...WasJbedellye^ and compacted in layers.. Compact ion is achieved by using special steel-wheeledcompactorvehicles which move to and fro acrossthe surface of the refuse.The exposedsurface of thewaste iscovered —•-•• • '' iff" at the end of the working day^y a layer of fill (usually excavated material). This helps to reduce nuisance and improve the visual impact of the operation.
37. The characteristics of the five existing landfills, are given in Table 2. The unit operating costs (which exclude the costs of transportation, occasional capital works and terminal works) range from $30/tonne to $60/tonne. The landfills at Shuen Wan and Junk Bay Stages I/II are marine sites. That is, they have been constructed next to the shore line. At these sites refuse is effectively being used to reclaim parts of the sea bed and foreshore.
38. Although there is no indication in Table 2 of a maximum operating capacity there is nevertheless a limit to the quantity of waste that can be accepted each day. This limit is determined by the capacity of the surrounding road network to cope with the RCV traffic, the layout of the tipping area, and the capacity of site equipment and machinery. None of the existing landfills is operating at maximum capacity and the maximum operating limits have not yet been tested. - 20 -
Table 2. Operating characteristics of existing and committed final disposal facilities
Date Intake Remaining Facility commissioned Capacity rate capacity /to be (m. tonne) in 1988 (m. tonnes) commissioned (t.p.d.) (as at Nov '88)
Pillar Point Valley landfill 1983 5.3 1996 3.64 (inclusive of extension) Shuen Wan landfill 1974 7.0 1954 2.00 (inclusive of extension) Junk Bay Stage I landfill 1979 10.0 6526 1.57 Jordan Valley landfill 1986 1.0 1005 0.51
Junk Bay Stage II landfill 1988 5.0 4250 5.0 Junk Bay Stage III landfill 1992 7.0 n. app. 7.0 West New Territories 1991 57.0 n. app. 57.0 landfill
North East New Territories 1994 37.0 n. app. 37.0 landfill
NB ; n- app. not applicable; m. tonnes million tonnes; t«p*d. = tonnes per day-
TREATMENT FACILITIES ~ INCINERATORS & TEMPORARY TRANSFER FACILITY
39* The three incinerator plants take in combustible waste and reduce it to 21 to 28% of its original weight and 5 - Tl» of its original volume by burning it. Bulky wastes, such as household furniture, are shredded prior to loading in the furnaces* - 21 -
40. Statistics relating to the operation of the incinerators are presented in Table 3. The normal operating capacity of all three plants combined is 2550 tonnes per day (t.p.d.). However Plant A at Lai Chi Kok incinerator has been closed down while electrostatic precipitators are installed. Hence operating capacity of the three incinerators is now therefore only about 2000 t.p.d.
Table 3. Operating characteristics of existing waste treatment facilities
•/r* Intake Operating Date Throughput rate secondary Facility wastes commissioned capacity in 1988 cost (t.p.d.) ( by ($/ tonne) (t.p.d.) weight)
Kennedy Town incinerator 1967 650 576 28 112
Lai Chi Kok incinerator
2 Station A 1969 550 / / ) ) 159 Station B 1974 450 465 21 )
Kwai Chung incinerator 1978 900 861 25 100
Chai Wan^pulverisation 1979 480 380 - 94 plant
Includes depreciation of vehicles, equipment, buildings and plant, cost of transportation and disposal of ash and cost of barging pulverised waste to landfill but excludes all capital costs and costs of transportation of waste to facilities and cost of disposal of pulverised waste at landfill.
Station A is closed for retro-fitting with electrostatic precipitators and the operating cost is based on both stations in operation, and includes the importation of electricity during this period.
Chai Wan pulverisation plant was originally a composting plant which ceased to produce compost in August 1987 * It had an original processing capacity of 480 tpd. The waste intake figure does not include waste by-passing the plant for direct off-Loading -to the barge for transfer to Junk Bay landfill. - 22 -
41. The incineration process is essentially self-sustaining, with refuse used as fuel. However for start-up ignition it is necessary to use fuel, oil. Additional quantities of fuel oil may also have to be burned from time to time to assist the combustion process, especially during the rainy season when the refuse is particularly wet. The older incinerators at Kennedy Town and Lai Chi Kok use significantly more fuel oil than that at Kwai Chung.
42. The Kwai Chung and Kennedy Town incinerators have the capacity to recover energy from the refuse, as does Station A of the Lai Chi Kok incinerator. Energy recovery is effected by the conversion, in a boiler, of waste heat to steam and the use of the steam to drive a turbine. In this way Kwai Chung incinerator produces sufficient energy for its own needs and could export electricity if a suitable recipient were located nearby. Station A at Lai Chi Kok normally produces sufficient electricity to run the whole plant (i.e. Stations A and B). Kennedy Town incinerator produces sufficient steam to generate power for the whole plant. Work was completed to modify the electricity supply system to make full use of the available power. Surplus steam is also available for export to the abattoir next door. Other resource recovery is limited to the magnetic separation of ferrous metals from the incinerator ash. However it has not been possible to find a commercial outlet for the recovered product and hence utilization of the magnetic separation unit is low.
43. The Ghai Wan pulverisation plant was originally a composting plant designed to treat principally organic refuse so that as much of the refuse as possible could be converted to compost by a controlled process of biological degradation. When operating normally degradation took place in enclosed fermentation chambers where the refuse was held for approximately 72 hours. Prior to entering these chambers the refuse was pulverised and screened to obtain the desired particle size, and ferrous metals were removed by magnetic separation. After fermentation, the compost went through a further screening and separation process during which much unwanted material, such as plastics and glass, was removed. - 23 -
44. The plant had a designed process capacity of 480 tonnes per day which could in theory produce 160 tonnes of compost, the difference being due mainly to rejected material which would have to be disposed of at a landfill, and a certain amount of moisture loss. In practice the maximum throughput that could be achieved was 360 tonnes per day* At this rate the theoretical maximum rate of compost production would be about 120 tonnes per day but this has never been achieved simply because it has not proved possible to find a market for the product. Although efforts were made in the past to ensure the plant received mainly organic refuse (for example by requiring RGVs serving markets to travel to Chai Wan to offload) the compost produced was nevertheless of rather poor quality, consisting of a considerable amount of granular particles of glass and plastics. The poor quality, in particular, the heavy metal content which rendered the product unsuitable for agricultural use, is thought to have been a contributory factor in limiting demand. As a result of the poor demand the only users of the produce were USD and RSD who used it for landscaping purposes. Their requirement was for only approximately 10 t.p.d., or one sixteenth of the plant's capacity. Because of the low demand compost production has now ceased completely and the refuse is now simply pulverised then transferred by barge to the Junk Bay Stage II landfill* The plant therefore acts as a simple transfer facility.
MARINE PIMPING FACILITY
45. Dredged material is not suitable for disposal in public dumps and since it is marine in origin the logical place to dispose of it is in the sea. Dredged material may be disposed of.at one of the three spoil grounds whose locations are illustrated in Figure 3. Excavated muds and other soils not suitable for disposal either at public dumps or at landfills are also dumped at sea. Dumping at sea may be carried out only under the terms and conditions of a licence issued by the Director of Environmental Protection under the Dumping at Sea Act 1974 (Overseas Territories) Order 1975. - 24 -
GUANGDONG SHENG
gj Spoil Ground r-~i Spoil Ground L..J (new alignment)
Figure 3 Location of spoil grounds for dumping of dredged and excavated materials
Plate 2. Excavated material loaded onto a barge for delivery to reclamation sites. Only unsuitable materials are disposed of by marine dumping - 25 -
46. The potential environmental effects of the dumping of dredged and excavated wastes at sea vary according to the nature of the material dumped. For example soils dredged from polluted areas such as typhoon shelters or those areas which receive substantial discharges from land-based sources (e.g. Kai Tak nullah) may exert a heavy oxygen demand on the waters into which they are dumped, and introduce substantial amounts of persistent pollutants such as heavy metals into the area of the dumping ground. However most of the soils dumped at sea in Hong Kong are relatively clean and adverse effects tend to be limited to the smothering effect on the sea bed. The water quality at the three existing dumping sites is monitored and the dumping appears to have had little or no effect upon either the concentration of dissolved oxygen or water turbidity.
CO-DISPOSAL FACILITY
47. The majority of chemical wastes are now simply poured down the nearest drain. For certain chemical wastes disposed of at landfill there exists a voluntary system of control. If a waste producer is in possession of a waste which he believes may be toxic or hazardous he can contact the Environmental Protection Department (EPD) for advice as to how to deal with it. Provided EPD is supplied with sufficient information the waste producer will be advised as to how and where the waste may be safely disposed of. If the waste is suitable for codisposal, a permit will be issued to the waste producer for taking the waste to the landfill at Junk Bay where it will be buried or co-disposed with municipal waste in a manner designed to ensure its eventual detoxification and/or neutralisation. The types of chemical waste currently disposed of at Junk Bay Landfill include asbestos, oily sludge, tannery off-cuts, oil-water emulsions and inorganic compounds. In future, Pillar Point Valley Landfill will also be used for the codisposal of asbestos waste, but other existing landfills will not be considered for the codisposal of chemical wastes other than asbestos. - 26 -
RADIOACTIVE WASTE DISPOSAL
48. A variety of radioactive wastes are generated in Hong Kong. The disposal of radioactive wastes is governed by the Radiation Board, a statutory body established under the Radiation Ordinance (Cap. 303). Since wastes which consist of sealed sources are returned to the suppliers of those sources, the main concern is with unsealed wastes. Some low level wastes (mainly from clinical laboratories) are permitted to be disposed of as ordinary refuse and sent to a refuse collection point in a thick thermal sealed bag. A limit, which depends on the precise type of radioactive species in question, is imposed on the amount of waste that can be disposed of by this route each month. Other types of radioactive wastes are either returned to the suppliers, encased or sealed for storage in an underground chamber, or destroyed at designated incinerators or the Kennedy Town Incinerator if the waste is suitable for combustion.
PFA AND FBA DISPOSAL
49. Although technically wastes, pulverised fuel ash (PFA) and furnace bottom ash (FBA) are in fact products of some value. Upto now Hong Kong Electric has been able to dispose of its PFA and FBA by selling-the materials to two companies for use as a cement additive and for use in the manufacture of cement blocks. China Light and Power is also able to sell a proportion of the PFA it produces, and all the FBA it produces, to companies involved in the production of concrete blocks and tiles and cement. However due to the limited market, and the considerable rate of production (over 0.8'million tonnes in 1988) the company has had to use other means of disposal notably -
a) disposal on land at a designated site in Hong Kong; b) export to Macau and China for use in landfill} and c) disposal to a lagoon. - 27 -
50. Disposal to a lagoon is a relatively recent innovation in Hong Kong. Lagoons have been constructed on the foreshore at Tsang Tsui in the New Territories. PFA is mixed with seawater and pumped into them as a slurry. It is allowed to settle and the decantrate is then pumped back to the power station at Castle Peak for disposal with the power station cooling water via a submarine outfall.
51 • The principal environmental problem associated with the disposal of PFA on land is dust (generated both at the site and by vehicles travelling to and from the site). Lagooning coupled with delivery of PFA in slurry form solves the air pollution problem and has the additional advantage that the PFA can be dug out of the lagoons at a later date for re-use as and when requirements arise and/or markets are identified.
Plate 3. Lagoon used for the storage of PFA slurry at Tsang Tsui, West New Territories
- 29 -
CHAPTER 4 PROPOSALS FOR IMPROVEMENT OF EXISTING ARRANGEMENTS
BACKGROUND
52. The main objective of the plan is to ensure adequate arrangements for the collection and disposal of various classes of waste in an environmentally satisfactory manner. This chapter addresses environmental improvement measures which may be adopted to overcome the problems and shortcomings identified with existing practices. (Details of the environmental problems are described in Appendix C)
WASTE COLLECTION
Household and commercial wastes
(a) Public sector
53. No major changes to the nature of the services provided by the collection authorities are required. The Government supports the Municipal Councils1 aim of providing efficient and environmentally acceptable services for the collection of household and commercial wastes, and will advise and assist the Councils in their efforts to improve these services. - 30 -
Plate 4. Unloading of refuse from plastic wheeled bins (equipped with self-closing lids) into a refuse collection vehicle
Plate 5. Automatic washing station at a refuse collection vehicle depot - 31 -
(b) Private sector
54. The considerable environmental nuisances that are often generated by private-sector arrangements for municipal waste collection stem from the fact that the private sector is completely uncontrolled. There is no authority or central employer with the power to ensure that private collectors meet certain environmental standards.
55. One possible means of ensuring that appropriate standards are met would be to establish a system whereby any person wishing to operate a collection service for household and commercial waste would require a licence to do so. The licence could specify the types of waste which it was permissible for the licensee to collect and could also include conditions relating to such matters as the types of vehicles to be used, the washing of vehicles, and the prevention of littering. The objective of such a licensing scheme would be to ensure the existence of a number of contractors capable of collecting and transporting waste in an environmentally acceptable manner* Waste producers would be free to engage any licensed collector to collect and remove their waste. The emphasis of the scheme would be on free competition within a controlled framework.
56. Provision exists within the Waste Disposal Ordinance for the collection authorities to license the collection of certain types of wastes. However the wording of the legislation is such that it may not be suitable as a basis for the establishment of a licensing system as described in the preceding paragraph. Even if it were, there could be considerable administrative difficulties in setting up - 32 -
such a system, not least the problems of inspection and enforcement. Because of these potential difficulties it is not possible to make a recommendation concerning licensing at this stage. It is therefore proposed that the three collection authorities should jointly examine the feasibility of establishing a licensing system for private collectors of household and commercial waste.
Industrial and construction wastes
57. Under the provisions of the Waste Disposal Ordinance the collection authorities are empowered to collect, inter alia, "trade waste11, which means "waste from any trade, manufacture or business or any waste building or civil engineering materials, but does not include animal waste". They are also empowered to license the collection of these wastes by private contractors.
In practice collection of these types of waste by the collection authorities is limited to the collection of commercial waste delivered to RCPs* None of the collection authorities collects either building and civil engineering waste or waste from manufacturing processes*
58* It is not considered that the collection and transportation of either construction waste or general industrial waste need to be controlled through a licensing system as the potential adverse environmental impact of these activities is limited and the resources that would have to be devoted to a licensing system cannot be justified at the present time. - 33- -
Clinical waste
59* Arrangements for the collection and disposal of clinical wastes were studied in 1982 by consultants to the government. A number of recommendations were made, aimed mainly at ensuring that firm guidance on the segregation and handling of such wastes was provided by the medical authorities and that standardised procedures were followed consistently throughout all medical establishments, especially those operated by the government. Despite this the situation remains less than satisfactory. In particular there is a need for consistency as to which wastes should be incinerated, which should be removed under special arrangements, and which may be discarded along with ordinary refuse. There is also a need to establish procedures to ensure that waste from private doctors1 clinics is properly dealt with. It is therefore proposed that :-
a) the Hospital Services Department and the Department of Health should re-examine, in conjunction with the collection authorities, existing procedures for the segregation, handling and subsequent collection of waste from hospitals and clinics with a view to developing a code of practice or directives to ensure consistency of approach; and
b) a further study should be carried out of the nature and extent of arisings of clinical wastes from private doctors1 clinics with a view to identifying a satisfactory means of collecting and disposing of those wastes.
Other wastes
60. The remaining wastes requiring consideration are "difficult11 (i.e. mainly organic and obnoxious) wastes and wastes posing special problems such as chemical wastes, and PFA. It is considered that in order to ensure that these wastes are collected and transported safely and with minimal environmental impact a licensing system needs to be established* It is proposed that this should be done as a matter of priority. - 34 -
61. For licensing purposes the wastes would be divided into two categories namely "toxic and hazardous11 and "difficult and special". Toxic and hazardous wastes would comprise mainly chemical wastes requiring special handling. Special and difficult wastes would comprise such materials as sludges, excremental waste, livestock waste, animal carcasses, and PFA . Contractors wishing to carry any waste falling into any of these categories would require a licence from the relevant waste collection authority. For chemical wastes the conditions would include a requirement that complete and detailed records be kept of each load of waste collected and delivered for disposal. It would also be necessary for the waste producer and the operator of the disposal facility to keep copies of such records. This "trip ticket system" would enable the waste collection authority (DEP for chemical wastes) to monitor the fate of all chemical wastes collected and disposed of in the territory. For wastes falling in the "special and difficult" category licence conditions would not need to be so rigorous as those for toxic and hazardous wastes. In particular waste producers and collectors would probably need only to keep a log of wastes collected and delivered for disposal.
WASTE DISPOSAL
Landfill
62. Odour at landfills arises both from vehicles delivering refuse to the site and from the site itself. Odour from vehicles delivering refuse to the site could be controlled in a number of ways i-
(i) the waste may be fully containerised; (ii) the vehicles should be cleaned regularly, both inside and out; and (iii) leakage of leachate should be avoided.
The use of bulk transfer vehicles or vessels would allow containerisation of large loads, coupled with the use of smaller RCVs on collection rounds for delivery to refuse transfer stations. The provision of vehicle washing facilities at the transfer stations will help the waste collection and disposal authorities in their efforts to improve the environmental standards of their operations. - 35 -
63. The problem of odour generation by refuse deposited at landfills is not severe, mainly because waste is collected and delivered to landfills daily. This means the waste has little time to produce malodorous decomposition products before being covered by more-recently-collected waste. To ensure that the problem is minimized, the area of the tipping face should be kept to the minimum consistent with operational requirements and the refuse should be well compacted and properly covered with earth.
64. As regards gas control, it is essential that all future landfills should incorporate properly engineered gas control systems. Such systems would include wells or sumps where gas would accumulate together with some means of drawing the gas off. Where landfills can be established close to industrial areas consideration should be given at an early stage to the possibility of collecting the gas and piping it to those areas for use as a fuel.
Plate 6. Landfill gas monitoring at ~ a purpose builbuilt borehole - 36 -
65. As rainfall in Hong Kong is high, leachate will always be a problem wherever there is a possibility of the contamination of groundwater, water courses or water bodies. As a general rule no leachate should be allowed to escape from landfill sites into groundwater or into water bodies which are subject to sensitive uses (e.g. fish and shellfish culture, or recreation). In practice leachate at inland sites can be properly controlled by lining sites with an impermeable membrane and installing an appropriate collection system prior to operation of the landfill. Leachate can then either be collected and treated on site prior to disposal via long sea outfalls or delivered for treatment at sewage works. At marine sites (i.e. those sites where a part of the sea bed is reclaimed using refuse) the problems are more complex. The use of synthetic liners is not feasible unless all the underlying marine mud is excavated. Work is currently under way in Hong Kong to assess the effectiveness and feasibility of using natural liners such as bentonite/decomposed granite mixture or marine mud for such sites.
661 One of the arguments against the use of landfills for waste disposal is that the land utilised will be effectively sterilised for many years after the site has been exhausted. Of particular concern are
(i) the fact that gas is likely to be generated for 50 years or more after the site is exhausted; and
(ii) the likelihood that due to differential settlement the land will be unstable for many years after the site is exhausted.
67. The problem of gas generation can be dealt with by the prior establishment of a proper gas collection system. However if venting points are necessary these could present an Impediment .'to any planned after-use. Settlement problems cannot be completely'overcome but it may be possible to reduce the adverse effects by ensuring that waste undergoes as high a degree of compaction as possible at the time that it is laid down* The in situ density achieved at Hong - 37 -
Kong's landfills at present is about 0.9 t/m3. If differential settlement is to be minimised and early use of landfills is to be o achieved an in situ density of at least 1 t/m should be aimed at. It would also help if landfills were to be completed and restored in stages (so that one area of the site is being landscaped while another is being filled). This would ensure that parts of the site could be brought into use earlier rather than having to wait for the whole site to be exhausted. Early cover can also help to reduce leachate generation. Final cover of up to 2 m of good quality soil, on top of a drainage layer and an impervious barrier, should be provided and vegetated to reduce soil erosion and water penetration. Gas control systems should also be installed to reduce gas migration problems and the associated fire and asphyxiation hazards. These measures would probably be sufficient to allow open space development almost immediately after a site is exhausted and in the long run might allow the construction of low-rise structures (one to two storeys) on spread footings.
Plate 7. A low-rise building structure erected at the Gin Drinkers' Bay landfill which is being restored in phases for passive recreation uses - 38 -
68. In order to properly restore the completed landfills for beneficial uses as well as to avoid gas migration problem, in particular for those landfills located in the urban areas with new housing and commercial developments in the neighbourhood, EPD is developing a landfill restoration programme. The programme will identify those landfills which require more urgent restoration works, which may include the installation of properly engineered gas and leachate control systems. The Government has already embarked on a restoration programme for the Gin Drinkers' Bay and Sai Tso Wan landfills which will eventually be developed by the Municipal Councils for passive recreation uses.
Plate 8. Lai Chi Kok incinerator is scheduled to be closed down upon the full commissioning of Kowloon Bay transfer station in April 1990
Incinerators and temporary transfer facility
In view of the environmental problems caused by the incinerators and the Chai Wan composting plant, these facilities will be phased out in favour of purpose built refuse transfer stations which will serve as a facility for the transfer of waste from small refuse collection vehicles to bulk transfer vehicles and barges. The waste will then be delivered to landfill sites located in remoter areas of the territory. This approach is further discussed in Chapter 5. - 39 -
Codisposal facility
70. The current practice of codisposal of certain chemical wastes with municipal waste is controlled through a permit system administered by the Environmental Protection Department (EPD). Due to the lack of alternative disposal methods, certain chemical wastes such as oil-water mixtures, paint waste and organic chemical residues which are recommended for chemical treatment or high temperature incineration are now disposed of at landfills by trenching in limited quantities. To improve the existing situation, a chemical waste treatment centre will be developed. This is further discussed in Chapter 5. At the same time, EPD has also commissioned a consultancy to advise the government on the proper practices and procedures in carrying out codisposal operations. The consultants have also recommended certain guidelines on the types and amount of chemical waste which can be safely codisposed. These recommended guidelines and procedures will be implemented to reduce the environmental impact of codisposal practices as well as for operational safety.
Plate 9.
Delivery of properly packaged asbestos waste to Junk Bay landfill for codisposal with municipal waste - 40 -
Legislative controls
71« Mention has been made of the need to establish appropriate licensing arrangements to ensure that private waste collectors operate to acceptable environmental standards. Likewise, an effective licensing system will also be required to regulate waste disposal. While disposal of wastes at sea is adequately controlled under the Dumping at Sea Act 1974 (Overseas Territories) Order 1975, waste disposal on land is not adequately controlled and amendments to existing legislative provisions will be required*
72* The existing framework for the control of waste disposal facilities is provided for in section 16 of the Waste Disposal Ordinance. Section 16(1) states that
"Subject to subsection (2) a person shall not use* or permit to be used, any land for the disposal of waste unless he has a licence from the Director [of Environmental Protection] to use the land for that purpose»lf
Licences issued under section 16 may, by virtue of section 23, be subject to such terms and conditions as the issuing authority thinks fit, and can be cancelled If those terms and conditions are not observed* While these provisions appear to be sufficient to control operators of waste disposal facilities they suffer from two notable deficiencies namely
(a) the uncertainty as to whether land used for the disposal of waste includes land on which treatment facilities, such as incinerator plants or transfer stations are operatedj and
(b) the fact that a list of exemptions in subsection (2) includes land used by the Civil Engineering Services Department for landfill purposes and unleased land In respect of which a licence has been issued tinder section 5 of the Crown Land Ordinance (Cap 28)* - 41 -
The effect of these deficiencies is to exclude all government- operated facilities from the requirement to be licensed and, hence, from effective and independent control over the environmental standards to which they are operated. This is all the more significant when one considers that government-operated facilities are currently the only waste treatment and disposal facilities in Hong Kong. It is therefore intended that section 16 be amended to extend its application to government-operated or owned waste treatment and disposal facilities and to clarify that a licence is also required to operate any waste treatment facility. A suitable system of inspection and notification will also need to be devised to ensure that licence conditions are observed.
73. With respect to the disposal of certain classes of waste, the Waste Disposal Ordinance has provisions for introducing regulations to exercise tighter controls. The Waste Disposal (Livestock Waste) Regulations 1988 have already been made for the purpose of controlling the on-farm disposal of livestock waste in an environmentally acceptable manner, with the controls being phased in over a period of 9 years. Regulations are also proposed for controlling the disposal of chemical waste* A trip ticket system will be introduced to enable the authority to exercise 'cradle to grave1 control whereby the movement of waste from the waste source to the final disposal point is closely monitored.
- 43 -
CHAPTER 5 WASTE DISPOSAL STRATEGY
74. In developing the long-term waste disposal strategy, due consideration has to be given to the increasing trends of waste arisings as illustrated inFigure 4 (for details see Appendix B). Various alternative options have been examined in Appendix D and the strategy to be followed is outlined in the following paragraphs. Emphasis has been placed on the disposal strategy for solid municipal wastes* since they represent a major percentage of the total waste arisings.
SOLID MUNICIPAL WASTES
75. Resource recovery, incineration and landfilling all have a role to play in the disposal of household, commercial, industrial and construction waste. Though composting is not an attractive option as previously demonstrated by the Chai Wan Composting Plant, other resource recovery methods could make a more significant contribution and private sector participation should be encouraged and supported as far as possible provided that the operation is financially and economically viable. Incineration should not be ruled out as an option though it is more expensive in comparison with landfilling and there will be difficulties in siting new incinerators.
76. For the planning horizon up to 2001, the continued use of landfill will be the major disposal option. The matters that remain to be resolved are
(a) the role of incineration and refuse transfer in Hong Kong*s waste disposal strategy;
(b) whether treatment facilities should be provided to handle privately-collected waste; and
(c) the development of waste minimization, resource recovery and recycling as an integral part of the waste disposal strategy.
* Solid municipal wastes include household, commercial, industrial, construction, and marine collected wastes. 1988 2001 (22500 tpd) (30000 tpd)
LEGEND :
Household waste + Marine collected waste Commercial, Industrial £ Chemical wastes
Construction waste Coal ash (FBA & PPA)
Difficult & other wastes
Difficult and other wastes Sewage and waterworks sludge; sewage works screenings; excremental, livestock and abattoir wastes? animal carcasses and condemned food and clinical waste.
Figure 4 Quantities of waste by category in 1988 and estimates for 2001 - 45 -
77. To assist in resolving the first two points, a computer- based planning tool known as the Waste Management Model (WMM) is being used. The WMM is designed to provide an answer (or answers, where input data are varied) to the following general problem :
"Given an expected pattern of waste production, the costs of building and operating various treatment and disposal facilities, and the costs of transporting wastes to those facilities, what facilities should be built, where, when and to what capacity?11
The WMM and its application are fully described in Appendix E. Final disposal sites
78. From an original list of some 50 possible sites, the Environmental Protection Department identified a total of 11 sites with the potential for development into landfills. These are as listed in Table 4. The locations of the 11 sites are illustrated in Figure 5. None of the sites are in or near urban areas.
Table 4 Capacities and calculated life times of 11 potential strategic landfills and two potential incinerators*
Capacity 2 Site m cubic Lifetime (years) metres/ t.p.d. Landfills Junk Bay South 28 15 Three Fathoms Cove 29 16 Bay south of Flat Reef 29 16 Site south of 28 15 Wong Mau Hang Shan Wong Mau Hang Shan 37 20 North of Crown Ridge 38 21 Tin Shui Wai 10 6 Nim Wan South 57 32 Nira Wan North 57 32 Siu Ho Wan 34 . 19 Kau Sai Chau 89 49 Incinerators Pillar Point 2400 25 Ha Mei Wan 2400 25 capacity expressed in million cubic metres for landfills, and tonnes per day for incinerators lifetime calculated for landfills on the basis of a daily intake of 5000 tpd - 46 -
GUANGDONG SHENG WONOMAI N
Figure 5 Potential sites for future solid waste disposal facilities in Hong Kong under consideration in 1983 study
79. Based on a costing study carried out in 1983, the estimated cost per tonne-of waste disposed of at landfill ranged from $38 to $75. The estimates take into account the construction, operation and restoration costs but exclude costs of transportation. Three of the sites in particular represent especially costly options as far as construction, operation and restoration are concerned. The sites in question are Three Fathoms Cove (Tolo Harbour), Bay South of Flat Reef (Tolo Channel) and Kau Sai Chau (Sai Rung). All are marine sites at environmentally sensitive locations and because of this construction costs are especially high. Initial runs on the WMM indicated that for these sites transportation costs would also be very high and this, in conjunction with the high construction costs, precluded them from further consideration. - 47 -
80. Of the remaining eight sites three (Nim Wan North, Nim Wan South and Tin Shui Wai) are located in the western New Territories, three (Wong Mau Hang Shan, a site south of Wong Mau Hang Shan and the site north of Crown Ridge) in the northern New Territories, and one (Junk Bay South or Shek Miu Wan) in the south eastern New Territories. The existing landfills are distributed in each of these regions thus providing regional disposal facilities. There should be at least three new landfills distributed on a regional basis for the following reasons :-
(a) by 2001 daily municipal .waste arjLsinjg^j^^ to ^amount tosome16^730tonnes. This quantity could not be handled by one or two landfills simply because of the strain that would be placed on the surrounding road network and on the sites themselves;
(b) considerable increases in arisings are projected for the western and north-eastern New Territories in particular and it would therefore be sensible to provide a disposal facility in each of these areas to help reduce transport costs; and
(c) there will continue to be a need for a final disposal facility in reasonable proximity to Hong Kong Island in order to contain transport costs for wastes from the urban area.
The sites have therefore been examined with a view to reducing the number to one in the western New Territories and one in the north. The adoption of Junk Bay South (or Shek Miu Wan) as a site for a landfill is confirmed in the absence of any alternative in the south eastern New Territories.
81. With regard to the western New Territories it has been decided to exclude the site at Tin Shui Wai on the grounds that to establish a landfill there could severely hamper planning for future development in the Tin Shui Wai New Town area. In order to facilitate the choice between Nim Wan South and Nim Wan North the - 48 -
WMM has been used to assess the equivalent costs per tonne of refuse disposed of. For this purpose the costs assessed were the costs of constructing and operating the sites, and the costs of transporting publicly-collected waste from the western New Territories catchment area (Tsuen Wan, Tuen Mun, Yuen Long) for disposal at each of the sites. The results indicate that the costs of establishing and operating a landfill at Nim Wan South would be about 12%% less than operating one at Nim Wan North. In addition the construction of a site at Nim Wan North would entail the resumption and clearance of a considerable number of properties and the displacement of many more people than would a site at Nim Wan South. The preferred site for the western New Territories is therefore Nim Wan South.
82. A comparison of the costs of operating the three potential northern New Territories sites for the disposal of wastes arising in the north east New Territories catchment area (i.e. wastes from Sha Tin, Tai Po and Sheung Shui) has also been carried out. The results indicate that the costs of waste disposal at Wong Mau Hang Shan and south of Wong Mau Hang Shan would be virtually identical while the cost of waste disposal at Crown Ridge would be marginally higher than the costs at the other two sites. Further investigations revealed that the Wong Mau Hang Shan site would have considerable advantages over the remaining two sites in that it would involve less land resumption and would be less disruptive for the local population. Wong Mau Hang Shan has therefore been selected as the most feasible landfill site in this area.
83. The list of potential landfill sites therefore reduces to :
Nim Wan South (West New Territories landfill - WENT), Wong Mau Hang Shan (North-east New Territories landfill - NENT), Shek Miu Wan (South-east New Territories landfill - SENT); and Sin Ho Wan (Lantau).
The first three must be considered as firm sites because they are regionally based. A landfill at Siu Ho Wan has not been further considered because of its reduced strategic Importance* The earliest possible date of commissioning of the WENT landfill is 1991 and that for NENTf 1993. SENT will not be commissioned until 1994* - 49 ~
Strategy evaluation to arrive at a least-cost plan for waste disposal
84* Having identified the potential final disposal sites it is necessary to decide upon the optimum provision of waste treatment facilities that will enable costs to be kept to a minimum. The basic treatment methods under consideration involve transfer stations and incinerator plants* To be viable options both types of facility would need to be located close to the centroids of waste arisings so that their relatively high capital and operating costs are offset by lower transport costs. Because of the need to comply with airport height restrictions, to avoid sites in close proximity to residential buildings, and to avoid areas where there is a high potential for entrapment of pollutants, only two possible sites have been identified where an incinerator could be constructed. These are at Ha Mei Wan, Lamma Island and Pillar Point, Tuen Mun. Based on the costing study in 1983, the estimated cost per tonne of refuse processed which would be incurred by building a 2400 t.p.d. incinerator with energy recovery at either site would be two to three times as high as landfilling cost; this has included the transportation and final disposal cost of incinerator ash produced. Preliminary runs with the WMM indicated that the costs for the transportation of waste which would be associated with the use of either of these facilities would be large and consequently the possibility of incineration as a treatment method has been excluded from further consideration within the planning horizon of 2001 used in this document.
85. The WMM has been used to investigate options for the future provision of transfer stations in combination with the final disposal facilities. {Waste transfer is a waste treatment technique that effects virtually no reduction in waste mass and Is aimed primarily at reducing the costs of transporting waste to a point of final disposal. The cost advantage would be greater for those final disposal sites located at a longer distance from the waste arisings - 50 -
areas. The concept involves the construction of a number of strategically - located transfer stations close to the centroids of waste arisings. Vehicles which have collected waste from the points of arisings deliver it to a transfer station where it is transferred, with or without treatment, into a larger vehicle for haulage in bulk to a final disposal facility. The large vehicle may be a lorry, if road transport is utilised, or a barge if transport is to be by sea. A transfer station may include facilities for the compaction of waste to increase the payload of the bulk transfer vehicles. A further advantage of using a transfer station to treat waste prior to final disposal is that it provides the opportunity for waste to be containerised prior to haulage to a final disposal site. This would help to considerably reduce the problems of odour and leachate during transportation. If direct discharge of waste to containers were to be adopted odour would also be reduced at the transfer station itself/I
86. Three waste management strategies, namely direct haul, transfer facilities for public sector only^j and transfer facilities for both public and private sectors have been examined. The results show that the environmental benefits that would flow from providing transfer facilities for both publicly- and privately-collected waste are achievable at no greater cost to the public sector than would be incurred by providing transfer facilities to deal with publicly- collected wastes only. The private sector too would realise savings compared with a system in which all privately-collected waste was hauled directly to landfills. It is therefore proposed that the capacity of transfer facilities should be planned to cater ultimately for both publicly- and privately-collected waste in the medium to long term and that this is achieved by approrpriate planning of transfer station capacity. - 51 -
Programme
87. To summarise, the proposed long-term plan for disposal of municipal wastes is one based on strategically located regional landfills together with a network of transfer stations constructed so as to provide capacity for dealing with both publicly- and privately-collected waste. This disposal strategy envisages the closure of the Lai Chi Kok and Kennedy Town incinerators at the earliest opportunity. Its major elements, incorporating the preferred options and the chronology, are as follows :
Year Event
1989 „ Lai jChi_ Kqk_irijcu^e£ator station B closed down upon recornmissioning of station A 1990 Transfer station commissioned in Kowloon Bay; Jordan Vatley / landfill and Lai Chi Kok incinerator station A then closed down 1991 ChajL Wan . pulverisajii^ that the development of a new transfer station on the same site may begin 1991 .. WENT strategic landfill commissioned; Pillar Point Valley - 92 landfill then closed down Island East transfer station commissioned in Chai Wan; Kennedy Town incinerator then, closed down 1993 ,...... NEN T strategic landfill commissioned; Shuen Wan landfill - 94 then closed down /x Island West transfer station commissioned in Western district Transfer station commissioned in Yuen Long/Tuen Mun Transfer station commissioned in Sha Tin SENT strategic landfill commissioned; Junk Bay/landfill then closed down 1995 - Transfer stations commissioned in West Kowloon, 2001 Tai.Po and possibly North Point Kwai Chung TSSInefafor^ will be closed down when the transfer station in West Kowloon is commissioned
This table does not show temporary disposal facilities that will be required as emergency backups whilst the main elements of the disposal strategy are being developed. - 52 -
88, The locations of the strategic landfills mentioned above are illustrated in Figure 6. The locations of the proposed and possible future transfer stations, also illustrated in Figure 6, are as follows:
Transfer station Location
Island East, HKI Site of the Chai Wan pulverisation plant Island West, HKI Western reclamation or Mount Davis North Point, HKI* Causeway Bay reclamation Kowloon Bay Sheung Yee Rd/Cheung Yip St. West Kowloon West Kowloon reclamation (site not yet identified) Yuen Long/Tuen Mun along Yuen Long - Tuen Mun corridor Sha Tin Area 65B Tai Po* Not yet identified
* possible future transfer stations
GUANGDONG SHENG N
Figure 6 . ..Proposed location. of. future refuse transfer '•' . " • •' ' stations; axid'Strategic landfills . - 53 -
The Kowloon Bay transfer station has a capacity of 1800 tpd, while the capacities of other transfer stations in the urban areas would be around 1000 - 1800 tpd. The transfer stations in the NT regions would have smaller capacities in the range of 500 - 800 tpd.
Plate 10. Artist's impression of the layout of Kowloon Bay transfer station
Plate 11. Schematic diagram of refuse transfer operation CONSTRUCTION WASTES
89, Though the three strategic landfills have adequate capacity for the projected waste arisings in the next 20 to 30 years, to cope with the increasing volume of construction wastes, the following measures should be adopted as far as practicable :-
(a) Waste Reduction
i) The buildipg industry to consider the reduction of timber waste at source; reuse of suitable materials on site; and segregating at source the undesirable waste materials (such as paper, timber, plastic) from building debris to increase the proportion of suitable materials for land reclamation purposes* ii) The provision of disincentives to dispose of inert construction waste at landfills through charging.
(b) Maximized utilization at landfills
i) The provision of incentives in the Works Contract in the use of suitable construction waste to substitute imported borrow soft material as cover materials* ii) The provision of a separate daily tipping face for the disposal of the remaining fnon~usablef inert construction waste where cover material would not be required, iii) Sorting of construction waste at landfills to facilitate further reprocessing of useful materials.
(c) Adequate provision of public dumping sites
i) Provision of long-term public dumping sites .on a •' . ,. ^ • '• ' •; regional /sub-regional basis to, meet the continual • •• •• ' requirement for /disposal of inert construction waste' . • '"materials* The provision' of these;.facilities should'
, ' ••.. ' ; ; tie in';with future long-term 'marine .reclamation ' developments, to be supplemented by barge reception , . • • /facilities ,at strategic locations , for .onward .transfer' to reclamation sites* ' '' • ' : - 55 -
ii) Allocation of suitable areas at new reclamations for the disposal of certain categories of the presently marginal or 'out of specification1 materials, taking into account environmental and site formation considerations. Examples may include areas above sea-level and/or areas behind seawall at marine reclamations.
Plate 12. Construction waste contains much useful materials such as timber and wood waste which should be segregated at source for reuse and recycling
DREDGED AND EXCAVATED WASTES
90. The preferred option is marine dumping with control exercised through the licensing system established under the Dumping At Sea Act 1974 (Overseas Territories Order) 1975. There are three existing spoil grounds for marine dumping. The site at Cheung Chau has already been realigned to increase its capacity. In light of the limited capacity of the existing sites and the increase in reclamation activity, it is essential to examine alternative sites to meet future disposal needs. Factors which would be taken into account in the siting of new spoil grounds include the effects on marine ecosystem, fisheries resources, human health and welfare, shorelines and beaches, shipping lanes and existing uses of the seafloor, as well as the available capacity and the distance of the spoil grounds from the major sources of waste. - 56 -
DIFFICULT WASTE
91. Landftiling has been and will continue to be adopted for the disposal of a small fraction of difficult waste. However, landfill is not the preferred option for certain difficult waste, for example diseased animal carcasses and raw livestock manure. Moreover, to conserve the landfill capacity for the disposal of the rest of the solid municipal waste which is comparatively much greater in volume, alternative disposal options will be the main elements of the disposal strategy for difficult waste as outlined below.
Sewage sludge andwaterworks sludge
92. Landfill, incineration and sea dumping are identified as possible options for the disposal of sewage sludge* A comparison of the costs of these three options has indicated that for sludge arising at treatment works which are in close proximity to moderately deep water sea frontage, dumping at sea is about 60% cheaper than dewatering followed by disposal at landfill, which is in turn about half the cost of dewatering followed by incineration. On the basis of this cost comparison and a subsequent detailed feasibility study by consultants it has been concluded that action should be taken immediately to arrange for the disposal at sea of all stabilised sewage sludges generated at the Sha Tin Sewage Treatment Works, with the option of extending this disposal plan at a later date to sludges arising in Tai Po and North Districts. The position of the proposed sludge disposal site is illustrated in Figure 7* Appropriate berthing and loading facilities will be commissioned in Tolo Harbour in early 1991.
930 As a safeguard against the possibility that the dumping programme might, have adverse effects the government has established a comprehensive environmental monitoring programme. *A major baseline study of the physical, chemical and biological characteristics of the area is currently being carried out. There will be a limited survey in 1991 and further comprehensive surveys will be carried out in subsequent years. The environmental effects will thus be monitored regularly and a major review will be conducted after five years1 operation with a view to deciding whether dumping should be allowed - 57 -
to continue and, if so, whether the quantities dumped may be increased to include sludges from Tai Po and North districts,
GUANGDONG SHENG
( Sludge Figure 7 Location of proposed sludge dumping ground 94, For sewage sludges arising in areas not in close proximity to a suitable waterfront, disposal will have to be to landfill. The sludge will first have to be dewatered and disposal carried out in such a way that it will not produce operational difficulties at the landfill or localised leachate, gas, and settlement problems. Prior experimentation will be necessary to determine the best way of mixing sludge with other refuse in order to avoid these problems. - 58 Codisposal of dewatered sewage sludge at Shuen Wan landfill 95. Since marine dumping is not seen as necessarily the best long-term option for the disposal of sludges, and there is a need to conserve landfill capacity, EPD is giving consideration to alternative, recently developed processes for dealing with sludges such as fluidised bed incineration, high efficiency filtration and the production of oil from sludge. 96. Options for disposal of water works sludge are limited to dumping at sea or discharge to coastal waters via a long sea outfall. Since a decision has been made to dump Sha Tin's sewage sludge at sea it is intended that Sha Tin's water treatment works sludge should be disposed of in a similar manner. As with sewage sludges, the possibility of disposing of alum sludge from Tai Po and North districts in the same way will be reviewed at a later date. Improved methods of dealing with water works sludges in other areas have not yet been worked out, and this problem will need to be addressed separately. - 59 - Livestock waste 97. Composting of raw manure for subsequent recycling as fertilizer has been identified as the primary means of disposal. In order to tie in with the phased implementation of the regulatory control on livestock waste disposal, the existing capacity for composting livestock waste has to be expanded according to the following programme : 1990 Ngau Tarn Mei composting plant to be expanded to a capacity of 25 t.p.d.; 1991 50 t.p.d. consolidation site to be commissioned at Site A in the north east New Territories; 1991 50 t.p.d. consolidation site to be commissioned in the south west New Territories; 1993 250 t.p.d. consolidation site to be commissioned in the north west New Territories; 1993 100 t.p.d. consolidation site to be commissioned at Site B in the north east New Territories; 1995 20 t.p.d. consolidation site to be commissioned in the south east New Territories; 1996 10 t.p.d. consolidation site to be commissioned in the Islands District. Plate 14. Collection of dry muck-out livestock waste at the livestock waste collection point - 60 - Animal carcasses 98. Cremation is the preferred method for the disposal of animal carcasses. The existing method of cremating dead animals at the abattoir incinerators is not desirable because the abattoir incinerators are designed to cater only for the destruction of any diseased animals which are orginally intended for slaughter. Consequently it would not be appropriate or possible to use the abattoir incinerators for this purpose on a long term basis. It is therefore proposed that a special cremator be constructed for the disposal of animal carcasses. The small quantities, high temperature and long residence times would ensure no significant air pollution. The ash would be disposal of at landfill. CLINICAL WASTE 99. Clinical waste should ideally be incinerated in purpose-built incinerators in order to safeguard public health. Incineration in municipal incinerators is not appropriate because of the danger of incomplete combustion. All future planned hospitals, whether in the public or private sector, should therefore incorporate incinerators with adequate 'capacity to deal with the wastes produced. The incinerators should be capable of achieving complete combustion of material* It is recommended that for public and private hospitals and. clinics whose incineration capacity is inadequate or cannot meet the air emission standards,-the ..clinical waste should be collected and disposed of at.a centralised facility, which could incorporate a cremator'.for dealing with animal carcasses as mentioned earlier. CHEMICAL WASTE ' , ' '. ' •' '. '• 100. ' ' ' ''.'Most .chemical • wastes' require .treatment'before'disposal* , A chemical waste treatment 'Centre will be 'developed.on Tsing Yi for this purpose..'. Its location is shown' in. .Fig 8. The centre'will incorporate physico-chemical' treatment processes, 'for aqueous, waste,: : an oily waste recovery process, and a high temperature Incinerator. - 61 - 101. The incinerator will deal with relatively small quantities of waste (about 40 t.p.d.). It will be fitted with up-to7date particle removing and gas cleaning equipment and will incorporate a stack with a minimum height of 75 m. The intake will be carefully controlled and this, together with the limited quantities of waste to be dealt with and the presence of modern pollution control technology will ensure that the plant gives rise to no adverse environmental impact. Reserved Site for Chemical Waste Junk Bay Treatment Centre Codisposal Landfill South East NT Landfill (future codisposal landfill) Figure 8 Location of the Chemical Waste Treatment Centre and the codisposal landfills 102, The residue generated from the treatment centre will have to be disposed of at landfill. It is intended to codispose the residue at Junk Bay Landfill (and the SENT landfill in the future). Waste which does not require prior treatment , for example asbestos waste and tannery offcuts* will be sent directly to the landfill for codisposal* - 62 - RADIOACTIVE WASTE 103. Existing methods of disposal of radioactive wastes are generally adequate. There is a possibility that some wastes currently disposed of by storage underground could be dealt with by codisposal at a landfill. This may allow for the establishment of a smaller, purpose-built, long term storage chamber. A separate study has been initiated to investigate these possibilities. PFA & FBA 104. The preferred option for disposal of PFA and FBA is by sale on a commercial basis, followed by lagooning if sale outlets cannot be found. Use of PFA and FBA in land restoration and reclamation is to be investigated as a possible long-term solution to the disposal problem. Plate 15. PFA land reclamation trial at Siu Lang Shiu - 63 - SUMMARY OF THE STRATEGY 105. In summary, with regard to the future waste disposal strategy, the following conclusions have been reached : i) for final disposal of solid municipal wastes, landfill coupled with a network of transfer stations is the appropriate disposal option; ii) construction waste should be reduced at source, and the unusable remainder sent to the public dumps for reclamation purposes or to the landfills for use as cover material as far as practicable; iii) dredged and excavated soils should continue to be dumped at sea with new marine dumping sites identified to meet the future needs; iv) sewage sludge should be disposed of partly at sea and partly at landfill; v) water works sludges should be disposed of at sea either by marine dumping or long sea outfall; vi) livestock waste should be composted for use as a fertiliser as far as practicable; vii) animal carcasses and clinical waste not incinerated at hospitals should be destroyed in a purpose-built incinerator; viii) chemical wastes should be treated at a purpose-built chemical waste treatment centre and residues should be subject to codisposal at landfills; ix) radioactive waste should be stored at a purpose-built long term storage chamber or possibly codisposed at landfills; and x) PFA and FBA should be sold for re-use in building products, or lagooned for long term storage, while its use for land restoration and reclamation should be investigated as a possible long-term disposal option. 106. The costs which will be incurred in constructing and operating the proposed major waste management facilities as required for (i), (vii) and (viii) have been estimated and are set out in Appendix F. - 65 - CHAPTER 6 THE WAY FORWARD PLANNING BEYOND 2001 107. Earlier chapters have examined the existing and future arrangements for the collection and disposal of various classes of waste. The growth in population and commercial and industrial activities inevitably brings about an increasing volume of waste. Major development schemes such as port development, urban renewal programmes and other large scale reclamations exert additional pressures on the scarce resources available for the disposal of municipal and other wastes. New pollution control legislation and programmes will also generate more sludges requiring disposal. 108. The emphasis so far in the Government's approach to waste management has been to provide secure long term strategies for the disposal of the growing quantity of wastes produced by our community, together with provisions to prevent environmental problems associated with waste collection and disposal. Strategies to limit the amount of waste generated must now be developed, and the recovery and recycling of wastes encouraged. THE OPPORTUNITY TO MINIMIZE WASTE GENERATION 109. The more affluent a society becomes, the larger the per capita waste generation* Excessive waste generation, apart from the fact that valuable resources are wasted, also exacerbates the waste disposal problem. To reverse the increasing trend of waste generation, there is a need to educate the public and to encourage a change in attitude towards waste generation. The industrial sector should also make serious efforts in reducing waste generation by better housekeeping and process control, suitable changes to their existing practices and adoption of clean technology. The servicing and retail sectors should also contribute by exerpising stricter control measures, for example, restriction on the free distribution of plastic bags and tighter stock-taking of those consumer products with limited shelf-life. The use of environmentally desirable packagings for consumer products would also contribute towards waste minimization and resource conservation. A - 66 - waste exchange scheme is also worth consideration by industry. The scheme involves the exchange of waste materials and hence will maximize the reuse of waste materials by various industries. THE OPPORTUNITY TO PROMOTE RESOURCE RECOVERY 110. At present, recycling activity is mainly export-oriented as most materials with recycling value are scavenged by scrap dealers for export to other countries. There is already a substantial waste recycling industry in Hong Kong. Over 1 million tonnes of wastes were exported in 1988, which is equivalent to 24% of the total arisings of municipal waste. This recycling activity generated nearly 2.2 billion dollars in export earnings in 1988. 111. An export-oriented recycling activity is very much dependent on the demand from overseas markets and is vulnerable to market forces beyond our control. Any sudden collapse of the market for a particular type of scavenged material would place a burden on the government to identify alternative disposal outlets. Therefore, apart from close monitoring of the extent of recycling activity, further opportunities to recover wastes and to establish stable markets for recycling should be explored and promoted. Plate 16. Baled waste paper intended for export to the neighbouring South-east Asian Countries - 67 - 112. The Environmental Protection Department has recognised that a lot of the waste materials that are currently disposed of at landfills may have comparatively low recovery value in commercial terms or may require more elaborate reprocessing and marketing efforts for the recycled products. It is the Government's intention, therefore, to identify practicable measures to promote, facilitate and support waste recovery and recycling schemes that have an overall beneficial effect on waste management. The principles of Government support and assistance being considered cover the following:- giving preference and assistance in the establishment of commercial recovery and recycling schemes that are able to reduce the demand for waste disposal; . giving favourable consideration in the procurement and application of recycled products within Government; increasing the effectiveness of the dissemination o*f information on waste recovery and recycling to the industry; and increasing the relative recovery value of waste materials through possible imposition of waste disposal fees on waste producers. 113. It remains the Government's view that direct participation in waste recovery and recycling activities is not appropriate for the Government* With its greater degree of flexibility and marketing ability, the private sector is better placed to embark on; resource recovery ventures based on innovative technology. The support measures being considered by the Government are mainly intended to complement the industry which has the necessary knowhow and flexibility required for viable recycling developments. 114* There is also scope for promoting a larger extent of waste separation at source so as to facilitate waste recycling. However any such arrangement would require more public participation and cooperation, and education will be an essential component of any related promotion campaign. - 68 - THE ROLE OF THE PRIVATE SECTOR 115. Although all Hong Kong's waste disposal and treatment facilities are currently operated by the government this does not mean that the private sector is necessarily to be excluded from operating such facilities* The design, construction and operation of waste disposal, and treatment facilities by the private sector, based on some form of contractual arrangement with the government, would have a number of potential advantages such as the transfer of professional experience, provision of financial incentives for good management and greater operational flexibility. It is therefore the government^ intention that in future the possibility of private sector involvement in the design, construction and operation of waste treatment and disposal facilities be investigated whenever it is appropriate* CHARGIHG POLICY 116. Currently, the government provides all waste treatment and disposal facilities free of charge* In the case of-household waste, householders are responsible only for the delivery of the waste to the collection points for removal by the collection authorities and in most circumstances the waste is delivered to the collection points by hired contractors* In the case of commercial and industrial waste suitable for disposal at landfills, waste producers are responsible only for the cost of transporting their waste to the landfills* In the case of chemical waste which is mainly discharged as liquid effluents, both collection facilities (sewerage systems) and disposal facilities (sewage treatment works) are provided free of charge* In the case of livestock waste, the collection service is initially provided free of charge but the subsidy will gradually be phased out so that the cost is eventually borne by the farmers. In the case of dredged and excavated wastes, the waste producers are responsible only for the cost of transporting the wastes to the marine dumping sites, and the licence fees only cover the administrative costs of the scheme. - 69 - 117. As earlier discussed, transfer stations have a key role to play in our future waste disposal strategy. Apart from the potential cost savings and environmental benefits, the network of transfer stations will also facilitate the even distribution of wastes to the three strategic landfills (ie. North-east NT Landfill (NENT), West NT Landfill (WENT) and South-east NT Landfill (SENT)). However, if full costs are charged at the transfer stations for privately-collected waste, private waste disposal contractors would have less incentive to utilize the service of the transfer stations, preferring to send wastes directly to the strategic landfills, which are provided free of charge. This may lead to an uneven distribution of the waste at the three landfills resulting in an early exhaustion of the capacity of the most popular landfill, apart from the operational difficulty of coping with a large number of small collection vehicles at a popular landfill. To reduce the cost disincentive and to encourage the full utilization of " transfer stations, there is a need to review the existing charging arrangement which has a number of inconsistencies as outlined earlier. LEGISLATIVE CONTROL 118. The Waste Disposal Ordinance has provisions for licensing of waste collection and disposal services. However, the ordinance has certain deficiencies which will have to be rectified by legislative amendments. At the same time, certain provisions cannot be implemented until the necessary regulations have been made. The major legislative amendments will be «- improving the legal definition of "waste"; reclassifying and defining various classes of waste to facilitate the division of responsibilities between various government departments and the municipal councils and for the purpose of licensing control; - 70 - defining 'disposal' to ensure all parts of the waste management chain beyond 'collections ie. reception, treatment and interim storage as well as final disposal, are controlled; improving the existing licensing provisions with respect to the collection and disposal of waste; extending the licensing controls to cover all government disposal operations; imposing greater responsibility on waste producers to assume the duty of care for certain classes of waste; imposing stricter control on the import and export of waste. - Al - APPENDIX A TYPES AND QUANTITIES OF CUREENT WASTE ARISINGS WASTE TYPES 1.1 The types of waste with which this document is concerned, the agencies effecting their collection and transportation, and the existing method of disposal adopted for each are summarised in Table A.I* In more detail the wastes are as follows. Household waste 1.2 Household waste is waste generated by individual households in the course of their normal daily activities. It includes bulky items such as furniture and domestic appliances as well as the type of material that normally finds its way into the average household rubbish bin (e.g. food waste, paper, plastics). It is collected and transported to a disposal point by the Urban Services Department (USD), the Regional Services Department (RSD) and by numerous private contractors. It is treated or disposed of at one of the territory's incinerators, at the pulverisation plant at Chai Wan, or at one of the territory's landfills. Street waste . . ' • , • • .• , • ' '. . 1.3 Street waste is essentially dirt and litter collected as a result of street cleansing activity by USD and RSD. It includes litter from litter bins and from beaches and country parks. It is disposed of in the same way as household waste. Marine collected waste 1.4 Marine collected waste includes both marine floating waste and waste collected from ocean going vessels moored in Victoria Harbour and dwelling boats in typhoon shelters. Marine floating waste is essentially the marine equivalent of street waste. Marine collected waste is collected in part by government-owned vessels under the control of the Marine Department and in part by private contractors. Opce collected the waste is delivered tq a marine waste reception point from where it is transported by contractor to a landfill for final disposal. Marine waste reception pointy are located in Kwun Toi*g, Kwai Tsing, Western and Causeway Bay. - A2 - Table A.I Estimated arislngs of waste types In 1988 (tonnes/day unless otherwise indicated) Waste type Ar Is ings Collecting Agency Existing Disposal Method 1 Household 4600a USD/RSD/private pulverisation/ incineration/ landfill 2 Marine collected 19b MD/contract landfill 3 Commercial 400 private landfill 4 Industrial 1400 private landfill 5 Construction 6500 private landfill 6 Dredged & excavated 48800° contract /private marine dump ing /pub lie dump materials 7 "Difficult" Sewage sludge 135d EMSD/private landfill/screening plants Water works sludge 4000 N.A. discharge to water course/submarine outfall Sewage works screenings 40 contract landfill Excremental waste 54e USD/RSD/contract /private landfill/sewage works/screening plants Livestock waste 2000f contract composting/recycling/discharge to water course Animal carcasses 6.58 USD/RSD/private cremation/ landfill/reprocessing Abattoir waste 35h USD/private landfill/reprocessing Condemned food 108 private landfill/reprocessing 8 Chemical 280 private discharge to drains/landfill 9 Clinical 61 USD/RSD/private landfill/incineration 10 Pulverised fuel ash 2600 private lagooning/recycllng 11 Furnace bottom ash 380 private recycling 12 Secondary Incinerator ash 480 EMSD landfill pulverised waste 380 CESD's contract landfill Footnotes a includes some commercial and all street waste and junk and bulky waste; b inludes 4 tonnes of refuse collected from ocean going vessels moored in Victoria Harbour and dwelling boats in typhoon shelters, the rest is marine floating waste. c unit in m,/day, does not include quantity disposed of at public dump or reclamation; d unit in m /day, 15% dry solid, does not include the small proportion which is sent to screening plants by the private contractors. 47» dry solids} mainly delivered to sewage works for digestion and therefore subsumed within the figure for sewage sludge (which is 15-35% dry solids), does not Include privately collected sludge. a small fraction of dry mucked-out waste is currently collected by EPD contractor for composting, A very small proportion is also landfilled. During 1988, nearly 700 tonnes of compost was produced. does not include waste reprocessed by USD1sby-product plant or private contractors, nor waste cremated at the abattoir cremators. does not include waste reprocessed by the private contractjors nor the USD's by-product plant does not Include waste destroyed at hospitals Incineratorsj for government institutions this is estimated to be about 5 tonnes per day? contract. « private contractor engaged by a government department private = private contractor operating entirely independently of the government N.A. = not applicable. • USD "as Urban Services Department RSD = Regional Services Department EPD s* Environmental Protection Department CESD - Civil Engineering Services Department EMSD = Electrical and Mechanical Services Department MD w Marine Department •'. • .' .'••'' ,•-.'." • •'• ',' '• • "! .'..'•. • .-.•.'.'•. - A3 — Commercial waste 1*5 Commercial waste is waste arising from all forms of commercial activity such as markets,, shops, restaurants and offices (but not factories). It is collected mainly by private waste disposal contractors although a proportion is collected by USD and RSD. The proportion collected by the private sector is disposed of mainly at landfill and the part collected by USD and RSD is disposed of in the same manner as for household waste. Industrial waste 1-6 Industrial waste is waste arising from any industrial undertaking within the meaning of the Factories and Industrial Undertakings Ordinance, Cap 59. It includes solid and semi-solid waste from all the major industries such as the plastics and textiles industries but excludes chemical wastes and for the purposes of this review wastes from the construction industry. Collection and transportation of these wastes is carried out either by private contractors or by direct labour from the undertakings themselves. All such wastes are disposed of at landfills. CenstrjjLCtIon waste 1.7 Construction waste is waste arising from building activity." It includes various types of building debris, timber, site clearance materials and mixed soft materials but, for the purposes of this review, excludes material such as building rubble which is suitable for disposal at public dumps* or reclamations. It also excludes excavated materials produced during site formation which are disposed of either at public dumps or at sea, depending on the nature of the material in question. Collection and transportation of construction waste is carried out entirely by the private sector and all disposal is to landfill. Dredged and excavated wastes 1.8 Dredged waste, normally termed 'spoil1, is waste produced as a result of dredging activity in the harbour or along the waterfront area for purposes either of keeping navigation lanes clear or of constructing a major new facility (er.g* the new container terminal at Kwai Chung). Excavated wastes comprise mainly completely decomposed rock,, residual soils, aluvium and marine sand and muds excavated during large scale civil engineering works* The former material is normally suitable for reclamation fill purposes and disposed of at public dumps, and the remainder is usually suitable for sea disposal together with spoil. Disposal at sea is controlled by licence under the Dumping at Sea Act 1974 (Overseas Territories) Order 1975. * Public dumps are areas, Invariably located in reclamations, where building rubble and excavated materials suitable for use in land formation may be disposed ofv They are designated as such by the Director of Civil Engineering Services. — A4 — Difficult waste 1.9 This category mainly comprises organic wastes which are especially liable to putrefaction and for which special handling, treatment and disposal arrangements may have to be made. Individual waste types falling within this category are a) sludge from sewage treatment works: it is currently disposed of at landfills; transportation is carried out by the private contractors, or direct labour from the Electrical and Mechanical Services Department (EMSD) if the treatment works is government-operated; some wet sludges are also sent to the screening plants; b) water works sludge: this is sludge produced as a result of the treatment of water with alum to remove fine suspended matter; the resulting sludge is gelatinous", inert, and basically inorganic; at present the arisings are mainly discharged from water treatment works directly into water courses; c) screenings and grit from sewage screening and treatment plants: these wastes are removed by a private contractor engaged by EMSD and delivered to landfill for disposal; d) excremental waste; this consists of nightsoil and sludge from septic tanks and aqua privies; it is collected mainly by USD and RSD. Some septic tanks operated by EMSD are de-sludged by a contractor, and some septic tanks are de-sludged privately. The wastes are delivered to landfill or to a number of sewage treatment works and screening plants for treatment and/or digestion; e) livestock waste: this is essentially faeces and urine produced by livestock; at present it is mainly disposed of simply by hosing down into the nearest stream although some is composted and recycled to land or used as fertiliser for fish ponds; f) animal carcasses: these comprise mainly cats and dogs which have died or been killed in the street, imported animals which arrive dead or which are killed or die in the depot or lairages and farm animals (chiefly chickens, pigs and cattle) which have died on the farm; cats and dogs collected by USD are cremated at the USD abattoirs; carcasses of cats, dogs, chickens, pigs and cattle collected by RSD were formerly cremated but are now disposed of at landfill on a temporary basis; dead animals unfit for human consumption are also reprocessed in the by-product plants by USD, and otherwise cremated; g) abattoir waste: this consists mainly of blood, dung, stomach contents and hair of animals slaughtered at abattoirs; the wastes from Urban Council-run abattoirs are removed by USD and the wastes from privately-run abattoirs are removed by private contractors;' a11 such wastes are either reprocessed at the by-product plant at the Kennedy Town Abattoir, sold to private contractors for reprocessing or disposed of at landfills. h) condemned food: this takes the form mainly of tinned or packaged food or frozen meat which has passed its expiry date or has for some other reason become unfit for human consumption; it is disposed of to landfill or, in the case of meat, by processing in the by-products plant at Kennedy Town abattoir. Chemical waste 1*10 This category encompasses a considerable variety of wastes of different chemical compositions. The major factors they have in common are that they are toxic or hazardous. As such they need not be solid or semi-solid and indeed include many liquid wastes such as acid and alkali wastes from the electroplating and printed circuit board industries. At present it is suspected that only a very small proportion of such wastes are properly disposed of, for example, asbestos and oily sludges disposed of at landfills. The vast majority are almost certainly simply poured down the nearest drain. Clinicalwaste 1.11 Clinical waste comprises offensive (eg. amputated limbs, excised organs), infectious (eg. soiled dressings), dangerous (eg. Pharmaceuticals and chemicals) or difficult (e.g. syringes) waste arising from medical and dental establishments or similar practice. Some of the wastes are disposed of at in-house incineration facilities; others are collected by USD under special arrangements and disposed of at landfill; still others find their way into ordinary commercial refuse deposited at refuse collection points. They are then collected by USD and RSD on ordinary collection rounds. Some wastes from Queen Mary Hospital are transferred to Kennedy Town Incinerator by the Medical and Health Department. Radioactive waste 1.12 Radioactive waste is essentially any waste containing or consisting of a radioactive substance as defined in the Radiation Ordinance, Cap. 303. Its collection, transportation and disposal are controlled by the Radiation Board which is established under the Radiation Ordinance. ±-.13 Radioactive wastes of short half life are required to be stored at the site of origin for such a period of time as is necessary to allow the radioactivity to decrease to a level which is sufficiently low for the wastes to be disposed of safely as ordinary refuse. Wastes consisting of sealed sources of longer half life are usually returned to the manufacturer or supplier overseas for - A6 - disposal. Those which cannot be returned are stored in a secure underground chamber managed by the Radiation Board. Encasing in concrete may be required for some sources. Radioactive wastes which contain or consist of unsealed sources, or materials contaminated by unsealed sources, are disposed of locally. Very low level waste is disposed of as ordinary refuse or, if liquid, poured down the nearest drain. A small proportion is also disposed of at the landfill under controlled manner. The remainder is incinerated or encased in concrete blocks or drums and stored in the secure underground chamber. Pulverised fuel ash (PFA) and furnace bottom ash (FBA) 1.14. PFA and FBA are process-specific wastes arising from the combustion of coal to generate power. The only producers of these wastes in Hong Kong are the two utility companies namely China Light and Power and Hong Kong Electric. The companies themselves make arrangements for the disposal of the wastes* At present disposal methods include recycling and the deposit of the wastes in lagoons. Secondary wastes .1.15 Secondary wastes are wastes produced at waste treatment facilities. In Hong Kong the only secondary wastes requiring disposal are ash from incinerators and pulverised waste from the Chai Wan pulverisation plant (upto mid 1987 the Chai Wan plant also produced some compost for disposal). Incinerator ash is removed by EMSD while pulverised waste is removed by a contractor engaged by CESD. All the wastes are disposed of at landfills. CURRENT WASTE ARISINGS 1.16 Table A.I also sets out the estimated arisings of waste by type in 1988. The estimates have been (a), derived from data collected by the Environmental Protection Department (EPD) during its twice-yearly survey of wastes delivered to government-operated facilities; (b) provided by government departments responsible for the collection or disposal of specific types of waste (for example, estimates of the arisings of sewage treatment works screenings and grit are provided by the Electrical and Mechanical Services Department); and (c) provided by private enterprises (data relating to PFA arisings) or consultants (data relating to arisings of chemical wastes). - A7 - 1.17 Because the EPD survey is carried out at disposal points rather than sources of origin the data generated therefrom are likely to lack resolution. Thus the figure for annual arisings of household waste includes street waste and some commercial waste which are collected by USD and RSD and delivered to disposal points together with household waste. It is not possible to provide an overall estimate of the quantity of radioactive waste disposed of in 1988 because of the variation in the types of radiomiclides and the form of the waste disposed of-. 1*18 A detailed breakdown of the many types of chemical waste, and their estimated annual arisings, is given in Table A.2. COMPOSITION OF HOUSEHOLD WASTE 1,19 It is noteworthy that household waste constitutes well over one-third the daily arisings of primary waste disposed of at landfills or incinerators* It is therefore waste which is likely to loom large in any strategic planning* Because of this it is important to consider its composition and physical characteristics as this could have a bearing on the waste disposal method or methods finally adopted* 1.20 The composition of household waste as determined from samples taken from municipal waste collection vehicles is presented in Figure A.I The largest single fraction is putrescible matter, with paper and plastics constituting the second and third largest fractions respectively. The presence of the relatively large putrescible fraction is reflected in the moisture content which, in surveys carried out in 1988, averaged 4070« 1*21 The information contained in Figure A*l is repeated in the form of a pie diagram in Figure A*2 along with profiles of domestic solid waste from other cities and countries'. Although the data in this figure must be interpreted with care (because the studies were carried out at widely differing times) it would appear that Hong Kong's domestic waste.may;. be characterised £S. being, ;^lj^ the content of paper*, metals and glass but relatively high in Clastic and putrescibles (but not as high in putrescibles as domestic waste in Singapore, Sydney and Melbourne). The relatively low paper and metals content is probably a reflection of the degree of recycling that takes place in Hong Kong* The relatively high proportion of plastics and low proportion of glass probably reflect the extensive use of plastic bags and containers and the limited use of glass bottles* These characteristics could indicate that conventional resource recovery methods for the treatment of Hong Kongfs domestic waste may not be applicable* - A8 - Table A.2 Estimated Current Axis ings of Chemical Wastes In Hong Kong In 1988. Quantity Waste Type (tpa) Acid 20,400 Alkali 36,400 Copper containing waste solution Acidic spent PCB etchant 8,400 Alkaline spent PCBa etchant 5,400 Copper waste solution from 140 other factories Zinc containing waste solution 13 Nickel containing waste solution 125 Other metal salts containing waste solution 1,200 Cyanide containing solution 110 Non-chromium bearing oxidizing agents 10 Chromium bearing oxidizing agents 55 Halogenated solvents 1,400 Non-halogenated solvents 1,600 Phenols and derivatives 2 Polymerization precursor and production waste 40 Mineral oil 5,600 Fuel oil 50 Oil/water mixtures 12,200 Pharmaceutical products 1 Mixed organic compounds 130 Mixed Inorganic compounds 70 Miscellaneous chemical waste 30 Interceptor & Treatment Plant sludge 40 Tank cleaning sludge 1,000 Tar, asphalt, bitumen and pitch 140 Tannery waste 400 Printing waste 90 Dyestuff wastes 70 Plating bath sludges 10 Paint wastes 650 Waste catalysts 4 MARPOL Annex Ib 5,000 MARPOL Annex IIC 500 Total (rounded) 101,000 PCB stands for printed circuit board Prevention of Pollution from Ships (MARPOL Convention). Chemical waste arising from the application of Annex 11 of MARPOL Convention* - A9 Publicly Collected Waste 35 No. of Area Samples £\[ Urban Area "f 30 Urban 214 • NT. CO NT, 110 0 25 ii 20 Q ±i CO O CL E UNCLASSIFIED O O 10 c co 0 t - Privately Collected Waste 35 No. of Area Samples 30 Urban 92 NT. 86 | 25 <4-. 20 \ CO o 15 CL E o UNCLASSIFIED O 10 CO Figure A,1 Waste composition - waste collected in urban area and New Territories 1988 ~ A10 - 33% 32% 20% 47% 26% 36% 18% Melbourne Sydney Tokyo 1985 1985 1983 34% 33% 28% 38% 18% 1% 3% 2% 4% Singapore 1987 31% 22% 17% 4% 11% 5% 10% 19% Hong Kong Berlin 1988 New York 1978 1984 32% 39% 16% 29% 18% 10% 11% 5% 11% 14% 17% 5% Switzerland Birmingham Pnrjs 1983 1974 1985 LEGENDS M ^!%v| Paper \ ^V-^'" V fe^?^ Metals |§^§^ Putreaclblea |§§§§§§ Fine Material jffijjsll Leather , Rubber & Wood | ] Others S$$$S$§I Plastics fegogo°| Plastics, Building Debris & Others Figure A,2 Composition of domestic solid waste in a number of cities - All - GEOGRAPHICAL DISTRIBIITIOM OF WASTE^ ^ISIMGS1BELIVERED| TO LAND-BASED FACILITIES 1*22 For the purposes of the waste arisings surveys Hong Kong is divided into 19 Waste Arisings Districts (WADs) comprising 53 Waste Arising Areas (WAAs). The boundaries of the WADs are shown in Figure A.3. The distribution of municipal waste arisings in 1988, by WAD and by type is given in Figure A*4* The variations between the regions reflect largely the relative differences in construction, development and industrial activity, and in population. Thus in Kowloon and the New Territories construction waste forms a much greater proportion of the total waste arisings than it does in Hong Kong primarily because of the ongoing development in the new towns as well as urban redevelopment. EXTENT OF WASTE RECYCLING 1.23 As discussed earlier, the relatively low content of paper and metals in Hong Kong's domestic waste is probably a reflection of active recycling that takes place. Though it is difficult to find out the extent of recycling, in particular the in-house activity in industrial establishments, the export statistics of recycled material could act as a go'od indicator. The past record clearly shows that the recycling activity is export-oriented. The volume and value of exported materials over the last three years (1986-1988) are tabulated in Table A.3. A12 Figure A.3 Boundaries of waste arising districts in Hong Kong - A13 o C CD O) c CO E « s 3 3 •§ (D •.« CL o ® § ? i £p c co O) JJtac. •»•» c 8 § « c H C 6 | i g LU o CD 0 CD co II (g | ^ 5! CO CO 5 o =O *1 15 -fr-2i od> LEGENDS Household Waste Commercial Waste Industrial Waste Construction Waste Difficult + Marine•••+. Clinical Wastes (Only include those wastes which are delivered to landfill for disposal) Figure A.4 Distribution of 1988 waste arisings by district - A14 - Table A 1986 1987 1988 Categories of Waste Materials Quantity Value Quantity Value Quantity Value (tonnes) ( '000) (tonnes) ( '000) (tonnes) ( fOOO) I) Wood & Paper 1) Wood (including sawdust) 1,334 1,110 416 343 10,327 7,525 2) Paper 503,033 259,139 582,057 403,220 559,430 471,631 Sub total 504,367 260,249 582,473 403,563 609,757 479,156 II) Glass Sub total 822 397 556 291 484 351 III) Plastics 1) Polyethylene 3,907 8,568 6,820 11,745 26,413 60,202 2) Polystyrene and copolymers 802 2,553 5,518 11,121 9,261 24,127 3) Polyvinyl chloride 4,940 10,479 8,958 19,895 19,969 50,867 4) Other plastic products in the 686 3,248 1,106 3,051 10,520 24,720 form of waste and scrap 5) Unhardened rubber 150 120 449 405 137 125 Sub total 10,485 24,968 22,851 46,217 66,300 160,041 IV) Ferrous Metal & Steel 1) Pig or cast iron 5 6 63 38 628 469 2) Alloy steel 250,783 216,798 319,959 278,363 370,508 500,533 3) Tin plate 1,170 855 - - 7 15 Sub total 251,958 217,659 320,022 278,041 371,143 501,017 V) Non-ferrous Metal 1) Copper 7,824 60,647 10,684 95,184 20,782 246,855 2) Brass and bronze 15,908 114,149 22,292 189,833 29,069 296,400 3) Nickel 387 5,143 524 7,181 269 8,822 4) Aluminium 21,331 139,730 25,453 220,033 29,631 348,013 5) Lead 2,379 2,641 3,323 4,251 2,547 3,754 6) Zinc 33 70 109 341 737 1,836 7) Tin 24 682 66 1,274 58 1,165 8) Magnesium 52 505 42 440 12 119 9) Non ferrous metal ash and residues 413 6,898 1,198 7,320 1,678 7,126 10) silver waste and sweepings 138 173,535 224 351,446 36 55,960 11) Platlnium waste and sweepings 0.4 23,869 0,4 47,342 0,1 5,968 12) Other base metals 885 6,944 762 10,172 - - Sub total 49,374 534,813 64,677 934,817 84,819 976,018 VI) Textile Fibre 1) Silk 35 785 66 3,099 29 1,892 2) Cotton 19,144 43,902 18,548 44,091 15,737 38,298 3) Man made fibres 1,126 2,276 985 1,802 691 1,518 4) Wool/other animal hair (not pulled) 437 6,898 542 9,188 413 7,939_ 5) Wool/other animal hair (pulled) 29 512 183 2,824 6) Old clothing and other old textile 6,206 10,778 9,295 21,037 4,082— 7,174 articles, rags, etc. Sub total 26,977 65,151 29,619 82,041 20,952 56,821 Total 843,983 1,103,237 1,020,198 1,745,330 1,153,455 2,173,404 - Bl - APPENDIX B PROJECTED FUTURE WASTE^ ARISINGS 2.1 While it is possible for most waste to be considered on a type-by-type basis, because of the overlap between collection authorities and the private sector and because of the lack of proper records, household, commercial and industrial waste must be considered either as publicly-collected waste (i.e. waste collected by the collection authorities and comprising mainly household waste) or privately-collected waste (i.e. waste collected by the private sector and comprising mainly industrial and commercial wastes). PUBLICLY-COLLECTED WASTE 2.2 The quantity of publicly-collected waste arising each year since 1974 is shown in Figure B.I, together with a plot of the publicly-collected waste arisings per head of population. Both are clearly on a rising trend, but the quantity of waste arising per head of population is not expected to continue to increase ad infinitum. In Tokyo, arisings per head have levelled off at 0.9 Kg per day. Since Tokyo is an Asian city it is presumed that it may serve as a reasonable model for Hong Kong. However, since the publicly- collected waste contains an element of commercial waste, and in light of the general trend of increase as experienced in Singapore where the per capita generation rate of mixed waste (ie. household waste and commercial trade waste) approaches 1*0 kg/day, the same figure of 1.0 kg/head/day is chosen as the limit of growth. 2.3 The data on arisings per head of population per day have been fitted to a straight line by linear regression and the equation obtained used to obtain a projection, also shown in Fig B.I, of future arisings per head, with the constraint that these should not exceed 1.0 Kg per day. Population projections obtained from the Census and Statistics Department were combined with projected arisings per head to obtain projections of total arisings of publicly-collected waste per day. These projections indicate that by 2001 the daily arisings of publicly-collected waste will be approximately 6230 tonnes. PRIVATELY-COLLECTED MIXED WASTE 2.4 Data on past arisings of privately-collected household, commercial and industrial waste are presented in Figure B.2. Arisings per employee have been fitted to a straight line by linear regression and the resulting equation used to arrive at projections of future arisings per head. These have been combined with projections of future employment in the manufacturing and business sector, obtained from the Census and Statistics Department, to produce a projection of the future total privately-collected arisings of household, commercial and industrial waste. This projection, which does not include chemical wastes that by 2001,4840 tonnes of privately-collected wastes will require disposal each day. B2 8,000 T3 ci 7,000 - •CsD 03 6,000 — _.--"" - 0 Quantity ,.--"' 155 1 5,000 O •f ,-- >> 0 .' 03 J2r» 4,000 J*^~* 1.00 ? 0 3 *~*^f Arisings/head ^~--'~"'~"" CL 3 jc .— ~~ *"** ~"* 03 CL 3,000 .r ^ * -V" ~""'"~ 0.75 "5. O Jig***** 'if. * ^ -~ "* 03 0 x^x^#. -* -*" *" " * Average growth rate 3.3% u. 2,000 I(8 * 0.50 a a3 1,000 i • i • i • i ' i • i • i • i ' i f I • I .• l • i * i i 0.25 1974 1978 1982 1986 1990 1994 1998 2001 Year Figure B.1 Forecast of publicly collected waste 6,000 •q By GDP/ £ 5,000 0) X* '' ra ^By employee' | 4,000 Quantity ^^^'^l . . CD ,-v^' •.---"By Historica A L 0 y:^''~^~*~** Trend 0 3,000 3,0 S - Q | 2,000 y* Arisings/employee __^--^* "'_ 2.0 fc 0. 0 - // ^"^-^ ^j^——"* 0 | 1,00"^ -5,0- - "*"* * Average growth rate 5.8% 1.0 |[ E O LJJ 0 OL 0 I ! I I I I I I ! I I !! I I ! I I I I I I I 1979 1983 1987 1991 1995 1999 2001 Year Figure B,2 Forecast of privately collected waste CONSTRUCTION WASTE 2-5 Past arisings of construction waste are presented in Figure B'.3. Since the 1986T 1988 arisings include a substantial quantity of building debris which could be diverted to public dumps, the 1986 - 1988 figures should be adjusted before using them as the basis for projection. These figures have been fitted to a straight line by linear regression and the resulting equation used to calculate projections of construction waste arisings up to the year 2001* Based on this procedure, the projected construction waste arisings in 2001 will be 5630 tonnes per day. DREDGED AND EXCAVATED WASTES 2.6 The annual arisings of dredged and excavated wastes for the past ten years are presented in Figure B.4. There is no clear trend and consequently the historic data cannot be used as a guide to future requirements-. An assessment of large scale development projects to be carried out in the territory in the next few years which are likely to produce large quantities of spoil requiring marine disposal has, however, been made, ..Based on the assessment it is estimated that a minimum of 30 x 10 m of spoil requiring sea disposal will be generated from those committed reclamation projects* It is anticipated that a number of large scale reclamation projects will be carried out in the next ten years, in particular those projects arising from the Port & Airport development study (PADS), and this will result in a substantial increase in the arisings of dredged and excavated wastes. DIFFICULT WASTE Sewage sludge ; 2.7 The large scale development of the New Territories in areas where the disposal of raw or primary^treated sewage would be at best unacceptable and at worst impossible, has led to a considerable increase in planned sewage treatment capacity* A number of new sewage treatment works will be built in the coming years, many of which will provide secondary sewage treatment and will therefore give rise to sludges requiring disposal in far greater quantities than at present. 2-.8 The projected arisings of sewage treatment works sludges are presented in Table B.I. The projections are based on the planned programme for the construction of new treatment works and on the assumption that the works will operate at their design capacities when commissioned. There will be some variation in the capacity of the plants to dewater the sludges produced'. Hence the variations in percentage dry solids indicated in Table B<.1<- A review of the sewage strategy is being conducted and this review may result in changes to the future planned arrangements for sewage treatment and hence a possible increase or decrease in the sludge disposal requirement. 7,000 -i TJ d. 6,000 - ^*, linear regression to obtain projected arisings for the period, &CO from mid 1 990's onwards ..-•'' 05 5,000 - O 4,000 - 1 3,000 - 0 O 2,000 - w 1,000 - O j_ _j _j_ | | i | f —|| | I H I I I Hi I II I I 1979 1983 1987 1991 1995 2001 Year Note: Projected Arisings based on past year figures which are adjusted to exclude building debris. Figure B.3 Forecast of construction waste 20 03 18 $, 16 CD,- 14 CO 12 O D5 10 "5. 3-' Q 8 •D HI 4 l •;' ;.... i .. n i T^ i r 1978 1980 1982 1984 1986 1988 Year Figure B.4 Quantities of dredged and excavated material dumped between 1978 and 1988 inclusive - B5 - Table Bsl Projected future arisings of sewage sludge (tonnes per day) Source Areas Year Sha Tin Tai Po & Other Fan ling (157, d-.s-.) (17%-35% Total (30% d.s.) d.s.) 1991 133 84 70 287 1996 171 103 249 523 2001 208 103 249 560 d.s. = dry solids Water works sludge 2.9 Water works sludges are currently discharged either to coastal waters via long sea outfalls or directly to water courses. They are therefore not included in the waste monitoring programme. However it is considered that disposal of the sludges to water courses is not acceptable and in future some other means of disposal will have to be found* The rate of production of water works sludge in 1988 was approximately 4000 t.p.d'* Increases in water treatment works capacity are planned for the future and these will give rise to additional quantities of sludge requiring disposal. Based on existing and planned future capacity for water treatment the quantities of sludge that will require disposal in the future have been calculated and are presented in Table B'^. Table B»2 Projected future arisings of water works sludge (tonnes per day) Source Area Year Sha Tin Tai Po & North Other Total (1% d.s.) (1% d.s.) (1-6% d.s.) 1991 3,200 320 1,500 5,020 1996 3,200 390 2,450 6,040 2001 3,200 800 2,550 6,550 d.sv = dry solids - B6 - 2,10 The present arisings of sewage works screenings and grit, which amount to 40 t.p.d* are equivalent to approximately 70 kg per 1,000 m of daily flow. The current planned treatment capacity is for an average dry weather flow of approximately 2.3 million m per day. This being so, the arisings of screenings and grit can be expected to increase to 160 t.p.d. by the year 2001. Excrement a 1 waste 2.11 Arisings of excremental waste are likely to increase in the coming years as toilet facilities in rural recreational areas and in village sites are improved and as greater emphasis is placed on the proper maintenance and regular desludging of septic tanks. Estimates of increases in septic tank sludge arisings have been made up to 2001 on the basis of planned septic tank construction in the New Territories and a collection rate of 80%. The estimates thus obtained are presented in Table B.3. Table B<*3 Projected future arisings of septic tank sludge (tonnes per day; 4Z d«s«) Source Area Year Tai Po & Sha Tin Other Total Fanling 1991 25 46 93 164 1996 26 48 100 174 2001 29 53 100 182 Livestock waste 2*12 The disposal of livestock waste was brought under control with effect from 24 June 1988 through the provisions of the Waste Disposal Ordinance (Cap. 354). The effect of the implementation of adequate control will be to stop livestock keepers (pig and poultry farmers) from discharging untreated livestock waste into water courses. Livestock keepers in certain (banned) areas will, be prohibited from keeping livestock* Those in other(controlled), areas introduced in a phased manner will have to choose between ceasing operation, treating, the wastes on site to an approved standard, or having them removed, treated and disposed of elsewhere in a proper manner* ' '•:••'•':'• '•-'"•;'.:•.'•••>.••:.'..;: •••':, .•/ ••'.'•'' •/'/:':"". ••• ,: '• • '. •••••: - B7 - 2.13 Four basic options for treating wastes are available to the farmers. Briefly these are : (a) Dry muck out - In this method faecal matter is removed before hosing out; faeces may be either fully composted, partially composted, or disposed of directly to the land as fertilizer or to fish farms; urine and washwater may be discharged to a soakaway or further treated to provide an effluent that can be discharged to a water course* (b) Wet muck out - In this method faecal matter is not removed before hosing out and the hosed out slurry must be contained. There are three means of treatment and disposal of the slurry : i) on-farm treatment giving rise to effluents which can be disposed of to a water course and sludge which must be collected and disposed of elsewhere; and ii) off-farm treatment - essentially as (i) but wastes must be collected and treated centrally; and iii) land application - the liquid manure can be disposed of directly to the land for agricultural or horticultural purposes or to fish farms. (c) Pig-on-litter - In this method, approximately 250 mm of sawdust mixed with a special bacterial product is used as a bedding material for pig raising* The pig waste is absorbed, decomposed and stabilized as it is evenly spread and mixed with the bedding material by manual operation and the movement of pigs* (d) Hybrid system - This is basically a combination of the dry muck-out and wet muck-out methods whereby the feacal matter is partially removed whilst the residual waste is hosed out for treatment. 2.14 The onus will be on the farmers to choose the appropriate disposal method and there is therefore some uncertainty concerning the quantities and types of waste that will need to be disposed of. However based on research carried out by consultants and by the Environmental Protection Department it is estimated that as a result of the new restrictions 30% of the farmers will go out of business. Of those remaining it is estimated that approximately 7070 will choose the dry muck out method and the remainder will choose the wet muck out method. It is not possible to say at present what proportion of the dry muck out waste would be fully composted and what proportion partially composted as this will depend on whether a market for the compost can be developed. - B8 - 21. 15 It is Intended that controls on livestock waste be phased in over a 9 year period from 1988. About one half of the waste arisings will be brought under control in the first three-year phase and most of the remaining waste arisings will be brought under control by the end of the second three-year phase. Bearing this in mind, and on the basis of the estimates of the proportions of farmers using different treatment methods the projected livestock waste arisings up to the year 1996 have been assessed and are presented in Table B',4. The quantity produced in 1996 is presumed to represent the terminal rate of production. Table B*4 Projected future arisings of livestock wastes requiring collection and disposal (tonnes per day; 15X Waste Type Year Solids sludge (dry muck out) (wet muck out) 1988 189 14 1989 225 15 1990 272 18 1991 397 26 1992 491 33 1993 508 34 1994 518 35 1995 518 35 1996 518 35 d.sv = dry solids - B9 - Animal carcasses 2r«16 Since the populations of stray animals (chiefly dogs and cats) are kept under control the growth in the number of animal carcasses requiring disposal is likely to be linked to the growth in the human population and the propensity of that population to keep pets, the number of imported animals, and also to any changes in the livestock rearing industry. It is not possible to make any prediction concerning the former but the numbers of carcasses of pigs and poultry requiring disposal should be reduced by about 30% when the livestock waste control scheme is implemented. For planning purposes it is presumed that the daily arisings will amount to around 8 tonnes in 2001. Abattoir waste 2.17 The arisings of abattoir waste are linked directly to the consumption of fresh meat within the territory which in turn is linked to the size of the population* It is possible that as living standards rise even more fresh meat will be consumed daily and the growth in abattoir wastes will therefore exceed the rate of growth of the population. For planning purposes it is assumed that abattoir waste arisings will no more than double in the next 15 years and that in 2001 the daily arisings will be no more than 70 tonnes* It should be noted that the estimate mainly relates to the quantity expected to be disposed of at landfills* Condemned food 2'. 18 There is no means of assessing likely future arisings of condemned food. Such arisings are likely to increase in the future as more food is brought into the territory to service the needs of the increasing populations Possibly the rate of increase will exceed the rate of population growth if, as a result of increasing affluence, the per capita food consumption increases. For planning purposes however it is assumed that the daily arisings will no more than double over the next 15 years and therefore the amount requiring disposal in 2001 will be no more than 30 t.pyd. CHEMICAL WASTE 2.19 Prediction of future arisings of chemical wastes is extremely difficult because to do so means taking into account the likely future expansion and/or contraction of each of the waste-generating industries* Nevertheless consultants commissioned by the Environmental Protection Department have made an assessment of future chemical waste arisings based on trends within the industries, movements in production rates, changes in employment patterns, and purchases of raw materials* Their estimates of future chemical waste arisings upto 1997 are presented in Table B*5. The estimates do not, and c annot, take into account any possib1e technological developments that might result in a change in either the quality or waste produced. - BIO - Table B.5 Projected Ar is ings of Chemical Waste In 1992 & 1997 (Units in tpa) Waste 1992 1997 Acid 22,000 25,000 Alkali 42,000 50,000 Copper containing waste Acidic spent PCBa etchant ) ) ) 19,000 ) 25,000 solution Alkaline spent PCBa etchant ) ) Copper waste solution from 150 160 other factories Zinc containing waste solution 13 14 Nickel containing waste solution 140 160 Other metal salts containing waste solution 1,300 1,400 Cyanide containing solution 130 160 Non-chromium bearing oxidizing agents 11 12 Chromium bearing oxidizing agents 59 68 Halogenated solvents 1 , 700 2,000 Non-halogenated solvents 1,800 2,100 Phenols and derivatives 2.2 2.4 Polymerization precursor and production waste 42 44 Mineral oil 5,700 5,900 Fuel oil 51 53 Oil /water mixtures 13,000 13,000 Pharmaceutical products 1 1 Mixed organic compounds 140 150 Mixed inorganic compounds 74 78 Miscellaneous chemical waste 32 35 Interceptor & treatmnt Plant sludge 42 44 Tank cleaning sludge 1,000 1,000 Tar, asphalt, bitumen and pitch 140 150 Tannery waste 400 400 -.,.-: Printing waste • .' :''.'.• : ': :;:.':. '"'... ;.'•• • , .".'• "",,: /• • " • , •.,•:•. •.', ''••••••. -;" "93 • ; ".• '-' 94 Dyestuff wastes 59 52 Plating bath sludges •••••••'••••,." 11 " ' ' / .'- 12 : Paint wastes . ;.' ;'.; ;' : •.,''.;'' ' .: '.•'•'•.''•• '." ' "••' '' "'•.• ;. •'••'-,'.."• ' ':' • "'• 700 750 Waste catalysts '..'.'• '•';..' ',4;;,., -'.••'.'•' ; •. •„ .- . 4 •.:•• ';. : ; :: ; . ./Total";-;." '. '. ''.'. .•• ' •/'• ' .' '/'.' .•••,'•'.•• ' "' .•:•'.'.'.';." " ':/ .;" -.' ;, •. ' 110,000 130,000 PCB stands for Printed Circuit Board, Notei All figures rounded up to 2 significant figures. No projections have been made for MARPOL arislngs due to the very wide range of possibilities• - Bll - CLINICAL WASTE 2.20 Estimation of future arisings of clinical waste is extremely difficult, partly because of a lack of historic data and partly because of the difficulty of predicting the likely rate of provision of private medical facilities. It is the intention that all new medical facilities should incorporate purpose-built incinerators and this should obviate the need for any additional collection of clinical waste by the collection authorities. However there will probably be a growth in the number of private doctors1 surgeries and clinics which would not possess adequate waste disposal facilities. To ensure an adequate safety margin in assessing waste disposal needs it is assumed that clinical wastes requiring special collection in 2001 will be up to 10 tonnes per day. RADIOACTIVE WASTE 2<.21 Like chemical wastes, prediction of future arisings of radioactive wastes is very difficult because the generation of such wastes depends very much upon developments in industry. Recently however the quantities of such wastes generated by industry have been declining as the waste-producing industries have themselves declined. There may be some increase in the rate of generation of radioactive wastes from medical establishments but broadly speaking the situation is unlikely to change greatly in future years. PULVERISED FUEL ASH (PFA) AND FUENACE BOTTOM ASH (FBA) 2.22 The sole producers of PFA and FBA are the electric utility companies. Projected future arisings of PFA and FBA are thus dependent on (a) the growth in the demand for power in the territory; and (b) the continued use of coal as fuel for the power stations. Both Hong Kong Electric and China Light and Power have made a commitment to the continued long-term use of coal as a fuel for their power stations. They have produced their own projections of future production of PFA and FBA based on their plans for increases in generating capacity and upon their own projections of growth in the demand for power. Projections provided by both companies of the future production of PFA and FBA are presented in Figures B.5. Production of PFA by Hong Kong Electric is projected to rise to approximately 400 Kilotonnes per year in 2001. The corresponding figure for FBA is 100 Kilotonnes per year in 2001. Production of PFA and FBA by China Light and Power is projected to rise to 1030 and 114 kilotonnes per year respectively in 2001. These projections are very broad estimates and may be subject to variations. For China Light and Power, projections for 1997 and subsequent years assume the development of new coal-fired power generation facilities in Hong Kong'. B12 1,600 —i PFA ACTUAL PRODUCTION Upper estimate 1,400 (+10%) ... FBA ACTUAL PRODUCTION PFA 1,200 — ,, Lower estimate Jg 1,000 — (-10%) CD CL w c 800 •o C/3 3 O 600 — 400 — Upper estimate FBA 200 — (+10%) Lower estimate (-10%) i r r i i i I I 1985 1987 2001 1986 1988 1990 1992 1994 1996 1998 2000 Year Note: Estimated arisings of PFA are conservative Figure B.5 Projected total arisings of PFA and FBA - B13 ,-•- PROJECTED TOTAL DISPOSAL MQUIREMENTS FOR MUNICIPAL WASTE 2,23 Based on the foregoing (i.e. a direct extrapolation of past trends and/or best estimates of likely future arisings), if current patterns of waste disposal are maintained in the future this will give rise, in 2001, to a land-based disposal capacity requirement of approximately 16730 tvp-.d'. This is the figure for projected future arisings of household, commercial, industrial, construction and marine collected wastes (grouped as municipal waste)* CONTROL TOTAL FOR MUNICIPAL WASTE 2'. 24 The projected future arisings of publicly-collected waste (i*er« principally household waste but including street waste and some commercial waste), privately-collected waste (i.e. commercial, industrial, and some household waste) and construction waste have been obtained by extrapolating past trends. ,,.The_J.mplicit: assumption behind these estimates there fore J^s^thaj:_ ^%^&rns_^of ^a.st.e generat ion wi 11 cont inue_ in ^ the future a long the .SMae^J-lnesj-s^ JElHXj^^ past. ThJ^s^as^sumption may well be unreasonable, especially for construction waste which is likely to depend,^cruciaTlylupAiilJEEk. economic activity of the territory and policy decisions made by the government regarding such matters as public housingconstruction, urban redevelopment and new town development. In view of the uncertainty surrounding the estimates it is considered advisable to check the predictions against a control total derived by other means. 2-. 25 _It is weJJ._jdoc quantity of wast£ .arisings^ is^ejscrjLbaibJ.em^s f §_funct^on_of^ a society's wealth, as indicated by its gross domesticjgroduct_^GDP). Hong Kong is no exception. Figure B.6 is a plot against GDP of the combined annual arisings of municipal waste'. 2.26 Thus if future GDP can be predicted with reasonable accuracy this will provide a means of establishing a separate control total for future arisings of municipal waste'. Projections'of GDP growth rate are produced regularly by the C&SD for planning purposes. In the medium terra (upto 3 years) these are based on an econometric model and in the long term (upto 2006) on the projected increase in the labour supply and the projected increase in productivity. The former is obtained from population projections and the latter from an examination of trends of productivity in the different sectors of the economy. 2.27 The projected GDP growth rate is 6<.0% p.a. upto 1992, 5.6% for the period 1993 to 1996, 5.2% for the period 1997 to 2001, and 4-.97* for the period 2002 to 2006. In order to draw comparison with the projected arisings based on past trends as mentioned in para. 2.23, the projection based on GDP growth is produced by excluding all building debris from the arisings data. On this basis, a projection of future waste arisings has been obtained and is presented in Figure B-. 7-. B14 - 18 i- 16 - 88 14 - co CD 87 I 12 13 Export quantity of waste ca Q 6 60 100 140 180 220 260 3 xlO 80 120 160 200 240 Current Year's Total GDP (HK$ million) Figure B,6 The combined annual arisings of waste as a function of GDP Quantities of Municipal Solid Waste (thousand tonnes per day) — L -0. ~i -i -A |\^ 3! CO O N) 4^ O) 00 O •- f* Jill i 3 O 00 ~~ P3 CD vw g" S~| 51 '"> -* C Q. CD ~TI q co co oo ^r^ |||| g_ '•^^ **s| %j& CO t^ j S to co o o o o ts> "° a O -3 a gTo^S > ""*" o I The predicted quantity of municipal solid waste projected on the basis of GDP growth is 18,560 t.p.d. in 2001. This projection, although it does not match closely with the projected estimate of 16730 t.p.d. based on past trends, does provide a useful cross-reference for future planning. GEOGRAPHICAL DISTRIBUTION OF FUTURE WASTE ARISINGS 2»28 Projected increases in population and in manufacturing and commercial sector employment have been obtained for each waste arising district and used to project future arisings of publicly- and privately-collected waste in each districts The projected future waste arisings thus obtained, aggregated by region, are presented in pictorial form in Figure B.8. The projections indicate that the relative quantities of waste arisings in Hong Kong show a slight increase over the planning period. However the relative quantities of wastes projected to be generated in the New Territories show a much larger increase in the next decade, with a corresponding decrease in the relative waste quantities in Kowloon. The projected arisings of construction waste show further increases in 1991. However, a decrease is observed from the mid 1990fs onwards, since various measures being pursued to reduce the quantity of inert construction waste requiring landfill disposal would likely bring about such a decrease in the long ternr. Bl? HONG KONG ISLAND ,44% 47% 56% 54% 18% 18% 38% 35% 22% 23% 23% 1988 1991 1996 2001 (2347 tonnes) KOWLOON 29% 18% 29% 37% 20% 27% 36% 53% 37% 1988 1996 2001 (5790 tonnes) NEW TERRITORIES 34% 20% 30% 34% 54% 34% 36% 1988 1996 2001 (4744 tonnes) Publicly Collected Waste Privately Collected Waste Construction Waste (excluding building debris for 1996 and 2001) Figure B.8 Projected future waste arisings by region and by type - Cl - APPENDIX C ENVIRONMENTAL PROBLEMS ENVIRONMENTAL PROBLEMS POSED BY EXISTING COLLECTION ARRANGEMENTS 3.1 Adverse environmental impacts associated with the collection of waste, whether by the public or private sector, arise from a) odour both from points where the waste accumulates prior to collection and from vehicles used for collection; b) non-containment of leachate at points where waste accumulates prior to collection and in vehicles used for collection; c) noise generated by the waste collection process; d) dust generated by the waste collection process; and e) littering along collection routes and at collection points* 3*2 In respect of the refuse collection services run by the collection authorities the main problems are (a),(b) & (c). 3.3 For vehicles, the odour problem can be kept under control by good housekeeping, specifically by ensuring that they are regularly and vigorously cleaned* At present the exterior of each RCV is washed two or three times a week using high pressure water jets, brushes and detergents, and plans are in hand to install automatic drive-in/drive-out washing facilities at a number of depots throughout the territory which will allow almost daily washing* For USD vehicles the tailgate unit, body floor, and side panels inside the body are washed 6 to 8 times a month. But for RSD vehicles the interior and the tailgate unit are washed much less frequently, at best once or twice a month and at worst only when a service or repair is required. As long as this is the case the problem of odour from collection vehicles will persist. 3.4. Permanent RCPs where appropriate incorporate facilities to. reduce the odour problem. These include activated carbon filters and vehicle exhaust extraction systems. They also include water points so that the walls and floor may be hosed down after every operation, and roller shutters which allow odour to be contained whenever the •RGP is not being used. Temporary RCPs on the other hand do not have extraction systems, nor adequate washing facilities and are not enclosed. Consequently they remain a source of odour nuisance, _ especially during the summer months. Washing down of temporary RCPs is carried out by street cleansing vehicles and where drainage - ^ systems are inadequate this can result in blocked drains and polluted streets and gutters. ."••/, ".;••'" •••.'/'•'..'•'..; • . .Y. : : . • ••.."..• ••.•• •'. •• . • C2 - 3.5 In the context of waste collection, ffleachatefl is the term used to describe water which has percolated through and/or been squeezed from refuse. Leachate generation is particularly severe when refuse which has become exceptionally wet (perhaps through being left exposed to rainwater) is loaded into RCVs. The problem of leachate at RCPs can be kept under control by regular washing of the RCP. The greater problem concerns leachate in vehicles which may be deposited on the road anywhere along a vehicle's route if it is not properly contained. 3.6 All RCVs operated by the collection authorities have provision for leachate storage, either by original design within the loading hopper and underbody runoff tanks, or by subsequent modification* USD and RSD staff are under instructions to drain off leachate at each RCP immediately after loading has been completed, and at the final disposal site. Spillage in the street may occur if the sump is not drained prior to embarking on a journey, if the seals on the vehicle are poor, or if drivers do not handle the vehicles with the specific objective of avoiding leachate spillage. A further problem is that drain pipes on the leachate sumps are liable to become blocked so that leachate spillage may occur even if good operating practices are adopted. 3.7 For purpose-built RCVs the means of controlling the leachate problem lies in adequate staff training and procurement of vehicles with effective seals and appropriately designed leachate sumps incorporating trouble-free drains. 3.8 Noise is associated with all traffic movements and the operation of virtually all machinery. The collection and transportation of refuse is no exception. Noise generation is one of the factors taken into account by the collection authorities when procuring vehicles and every effort is made to ensure vehicles do not give rise to a noise nuisance. 3*9 In the private sector, odour, leachate, noise, dust,, and littering are all significant problems. However because the private sector generally collects waste from premises with their own storage facilities, and because this generally means collecting large numbers of loads of relatively small quantities, the problems that arise tend to be associated more with collection vehicles and practices than with storage prior to collection* 3.10 The majority of vehicles used in the private sector for waste collection are not designed for handling waste in an environmentally acceptable manner. The vehicles usually have no means of leachate containment and where waste collected consists of substantial amounts of putrescible material leachate spillage l^s always a serious environmental nuisance, especially during the rainy season. Because the vehicles are frequently not enclosed they often leave a trail of litter along the routes which they ply» Generally, little effort is made to ensure that vehicles used are not excessively noisy. - C3 - ENVTRONMEOTAL PROBLEMS ASSOCIATED WITH WASTE TREATMENT AND DISPOSAL FACILITIES Landfills 3.11 Generally the existing landfills suffer from the following environmental problems, although not every site suffers from all of them - (a) inadequate odour control; (b) inadequate gas control; (c) inadequate leachate control; and (d) differential settlement. (a) Odour 3*12 Odour from refuse is inevitably associated with any waste disposal facility* At landfills it arises from two sources namely vehicles delivering refuse to the site and the site itself * In Hong Kong these problems are experienced at every site but at Jordan Valley the problem of odour from the site itself has be.en brought partially under control by ensuring a) that a cover of inert fill is spread on the refuse two or three times a day instead of only at the end of the day; and b) that the refuse is disposed of in narrow tipping bays and laid in relatively thin layers so that it can be well controlled and compacted and the area of the tipping face kept to a minimum* There is, however, no gas control and gas is also an odour source. At the other landfills cover- is provided only at the end of the day and the practice of using narrow bays and tipping in thin layers is not followed. (b) Gas 3%,13 Gas is produced by all landfills containing organic waste. It is the result of the biological decomposition of refuse and consists mainly of methane and carbon dioxide, generally in the proportions 50 - 60% to 50 — 40%.' The gas is flammable and, under certain conditions, explosive* Depending on the quantities of trace contaminants, particularly those of sulphur compounds, it may also be malodorous* ~ C4 - 3.14 At Hong Kong landfills, arrangements to vent the landfill gas have been made by inserting into the waste cell a number of perforated pipes through which the gas may escape into the open air* There are two major problems associated with dealing with landfill gas in this manner namely : - a) the pipes tend to become blocked, bent or broken by natural movement of the landfill so that their efficiency as gas collectors is greatly reduced, with the result that gas which is unable to escape moves sideways or downwards into the surrounding soils and escapes through fissures in nearby rock faces; and b) when moderately efficient gas collection does take place potentially explosive conditions are created in a zone at the mouth of the venting pipe where the gas mixes with air. This practice is not acceptable environmentally and has now been discontinued, and action is in hand to evaluate alternative arrangements at selected sites. The construction of any new landfills must incorporate adequate gas collection systems. (c) Leachate 3<*15 In the context of landfills, leachate is the term used to describe water which has permeated through the waste cell. It is a solution and suspension of inorganic salts and the products of decomposition of the refuse* Its precise composition depends largely on the nature of "tie wastes placed in the landfill, and the conditions of decomposition (e*g* whether aerobic or anaerobic, mesophilic or thermophilic). It is a potentially highly polluting substance as it may contain salts of heavy metals in solution and may exhibit both a high biochemical and a high chemical oxygen demand. Of particular concern is its potential to pollute groundwater supplies* 3.16 In Hong Kong leachate collection systems are installed only at the inland landfills, that is Jordan Valley and Pillar Point Valley* Each of these landfills possesses a network of collecting drains-. At Pillar Point Valley the leachate passes into the sewerage system, from which it is discharged into the Urmston Road waters* JVt^ Jordan Valley it passes into the foul sewerage system and is " eventually discharged into Victoria Harbour via the Kwun Tong ^^IliBSl"?!??! and submarine outfall* At the marine sites (that is, at *§huen Wan and Junk Bay Stage I) there has in the past been little attempt to control leachate flow and disposal. At Shuen Wan there are a number of sumps in which leachate is collected before soaking away through an earth bund into Tolo Harbour* JkL. Junk .Jay.- these- is ,np , deslgned^sump and .leachate tends to pond and accumulate in various RljaSfisJt>JBhind.tfce. sea wall* It then" permeates through the sea wall ; bS*£Jthe^^ This situation is "environmentally undesirable, particularly at Shuen Wan where the leachate discharges into the serai-enclosed waters of Tolo Harbour* However in accordance - C5 - with the original project scope action is now in hand to construct a permanent sea wall around the landfill, behind which will be installed leachate interception drains. The leachate will be collected and pumped to Tai Po sewage treatment works for treatment prior to disposal. For all future landfills, whether at inland or marine sites, the possible need to incorporate leachate containment and treatment systems will be addressed in a comprehensive environmental impact assessment. (d) Differential settlement 3.17 All landfills suffer to a greater or lesser extent from settlement caused by the weight of the upper layers of material gradually compacting the lower layers, and by the decomposition of refuse within the waste cell. At a landfill site at Gin Drinkers1 Bay which was formerly operated as a completely %conj^plled open dump, settlement ranging from 0.3 m to 3 m has been recorded over periods ranging from 21 to 66 months, long after the tip had been closed. In addition, differential settlement occurs when the degree of compaction or the composition of the lower layers of refuse is not uniforms This leads to an uneven ground surface and tends to damage any installed services, utilities or building structures* Clearly differential settlement of this nature greatly reduces the usefulness of the site once the landfill has been completed. 3.18 Other problems that might be expected at landfills are generally of little significance in Hong Kong* Four of the existing five sites are in relatively remote areas so noise is not usually a problem-. Pests and vermin are kept well under control by the practice of covering the refuse with inert fill and by regular spraying with pesticides and rodenticides* Bird nuisance problems are minimal. Municipal incinerators 3'. 19 Due to their locations, the existing municipal incinerators represent aserious source of air pollution in the urban area and a health risk to those living or working nearby. The major concern is not the more conventional pollutants they emit, such as particulates, chlorine, carbon monoxide and oxides of. sulphur and nitrogen, although these too represent a problem; the major concern is that they emit, also, from time to time, quantities Qf^.jLlgfiix^toxIicT'" substances such as dioxins and heavy metals which,even in trace quantities, represent a serious health hazard. 3.20 Whilst it is possible to minimise the emission of the more conventional pollutants by standard air pollution control technology (at a cost), this is not the case with the toxic substances mentioned. To eliminate the toxic emissions would require either the rebuilding of the present incinerators so as to incorporate the very latest hijgh^tempewture emission control technology (at vast expense) or to remove the, materials that give rise to the toxic substances before they are burnt'., This latter option is not practicable, however, as it would entail sorting all of the refuse by hand prior to incineration to remove the offending materials, which include batteries, PVC products, spilled or packaged insecticides, etc. Neither option is therefore realistic'. - G6 - 3^21 This is not to say that all municipal incinerators would be unacceptable from an air pollution point of view. An incinerator that is well designed, maintained and operated and which is situated in a well ventilated area reasonably remote from major centres of population or agriculture would not pose significant air pollution problems. The present municipal incinerators, however, do not satisfy all of these criteria and pose a definite health risk. The incinerators at Kennedy Town and Lai Chi Kok are of particular concern as their plumes often impinge upon residential properties. The Kwai Chung incinerator, being more modern and slightly better situated, is of relatively less concern but is also not acceptable from an air pollution point of view* 3-22 Although the more serious air pollution problems from the present incinerators are intractable, action has been taken at least to reduce the level of particulates emitted by installing electrostatic precipitators to the chimneys of the incinerators. Precipitators are already fitted to the Kennedy Town and Kwai Chung incinerators as well as Station A of the Lai Chi Kok incinerator. The effect of the precipitators when correctly operated and maintained is to significantly reduce the quantities of particulate matter emitted, thereby greatly reducing the visible pollution from the incinerators* The only practical way to overcome the more serious air pollution problems, however, is to phase out the existing incinerators. Chai Wan. piilverisatioiJi^ plant 3f*23 Environmentally the main problems with the plant in both its past and present use are odour and scattering of refuse by the wind during barge loading* The sources of odour are the refuse reception chamber and the barge onto which refuse is loaded. The best way to overcome the problems would be to containerise the waste prior to loading onto the barge. - Dl - APPENDIX D EVALUATION OF ALTEHNATIVE DISPOSAL OPTIONS 4-1 For convenience the discussion of future possible arrangements for the treatment and disposal of wastes will be divided into a discussion of methods to be used for municipal waste which is currently disposed of mainly to landfill, difficult waste, and other wastes for which special arrangements are made (dredged and excavated soils, PFA and FBA, and chemical wastes)'* MUNICIPAL WASTES 4.2 Options for dealing with the arisings of municipal waste (which includes mainly household, commercial,industrial and construction waste) may be divided into those entailing treatment and those entailing disposal. Treatment methods are characterised by the fact that after processing there will always remain some waste residue requiring disposal-. Treatment processes include a) all resource recovery methods; b) incineration; and c) transfer. Disposal methods are those methods entailing the final disposal of wastes and are restricted to a) landfill 5 b) dumping at sea; and c) discharge to coastal waters down long sea outfalls (for a few wastes only). 4.3 The divisions between these two categories are not hard and fast. Incineration, for example, is effectively a disposal method .for 70%.of its waste intake since this proportion of the intake is discharged to the atmosphere after combustion. Landfill, on the other hand, has the potential to operate as a resource recovery method if gas generated within the waste cell is collected and used. Treatment methods • • '•. • •"••;.•••' •'•• '.•: '•".•.'.•' ."'. '''; . /;:'' ' -"•::."• ..•''•. (a) Resource recovery^ 4.4 Resource recovery is here taken to mean the processing of parts of the waste stream to yield re-usable products such as energy, ~ D2 - fuel or specific materials. It should not be confused with recycling, which is taken to be the separate collection and processing of specific waste types for rapid sale or re-use (e.g. collection of aluminium beverage cans and subsequent export of aluminium metal). The complexity of resource recovery methods ranges from composting, which involves a relatively simple technique for the stabilisation of organic refuse by bacteria, through processes which are aimed at the production of fuels from refuse, to full scale resource recovery which involves the separation and processing of various fractions of the waste stream to produce usable products. In the context of planning for waste disposal in Hong Kong, resource recovery methods suffer from a number of disadvantages as follows (i) they usually require substantial investment in plant and machinery and tend to be expensive; (ii) they may involve processes which have not yet been adequately proven; one potentially attractive resource recovery method is pyrolysis (the thermal decomposition of organic material in the absence of oxygen to produce liquid or gaseous fuels) but unfortunately most pyrolysis processes appear to have been tested only on a laboratory or small pilots-plant scale; experience on near-commercial scale is very limited and certainly not sufficient to be able to recommend the method for treatment of Hong Kong's waste; (iii) the viability of resource recovery methods depends upon uses or markets being found for the materials recovered; experience with the Ghai Wan composting plant has shown how difficult it can be to ensure that the product recovered is marketable; and (iv) invariably with resource recovery processes, a substantial residue of waste remains which still has to be finally disposed of; the amount requiring final disposal may be expected to range from 20 to 40% of the intake but if attempts to find markets for the products fail, up to 100% of the intake may require final disposal; the Chai Wan composting plant is again a case in point. 4.5 Perhaps the most important of the above disadvantages are (i) and (iii)y Resource recovery methods are in fact little different from any manufacturing process'* They involve the processing of a raw material (waste) to produce products (e»g. metals, compost, liquid and gaseous fuels) for which outlets have to be found. To reduce the costs of the recovery processes the products need to be marketed and sold. Otherwise the recovery process will have no significant advantage over straightforward disposal techniques. If the public sector were to adopt resource recovery as a means of waste treatment the cost to the community would be likely to depend upon the efficiency with which the plants were operated and the skill with which the products were marketed and sold. - D3 - Marketing and selling of products recovered from waste are not areas in which the public sector has any great expertise* This, coupled with the other disadvantages of resource recovery methods leads to the conclusion that such methods should only be adopted by the public sector if (i) any financial costs are likely to be outweighed by social and environmental benefits; (ii) there are good arguments for developing the technology at public expense; or (iii) there is some strategic value in the recovery of a specific type of wastes In the context of Hong Kong only one waste type, livestock waste, justifies public sector involvement in resource recovery methods. 4v6 Although public sector involvement in waste treatment processes based on resource recovery is considered to be unwise, this does not mean that proposals from the private sector to set up treatment facilities based on resource recovery would be discouraged. On the contrary such private sector initiatives are to be welcomed and, as far as is practicable, supported'. (b) Incineration 4'. 7 Incineration is a method of treating and disposing of waste materials by controlled combustion* It includes an element of resource recovery in that waste heat is frequently harnessed to allow the generation of electricity. However its primary purpose is the destruction of waste. Globally it is probably second only to landfill as a method of waste treatment and disposal. In Hong Kong it is the method used for the treatment of approximately 38% of current domestic waste arisings. 4'.8 On the technical and environmental side incineration suffers from a number of disadvantages as a method of waste treatment and disposal. These are as follows :~ (i) it is limited to combustible wastes so that a suitable repository still has to be found for non-combustible wastes; (ii) it does not dispose of waste completely; a residue constituting 21 ~ 28% dry weight of the refuse burned, and 5-7% of the volume, remains to be disposed of after incineration; and - D4 - (iii) it has the potential to be a major cause of air pollution. 4.9 Against the disadvantages there are a number of advantages namely :- (i) a relatively small area of land is utilised; (ii) when the facility reaches the end of its useful life the landuse of the site is not restricted as it is in the case of a landfill; (a similar plant or other replacement facility would, however, have to be provided elsewhere); (iii) it offers a means of recovering energy from waste by using the refuse as a fuel for an electricity generating system; (iv) it offers a. means of recovering certain materials (e.g. ferrous metals) from waste with relative ease; and (v) notwithstanding the fact that a residue remains to be disposed of after the waste has been incinerated, the reduction in volume (approximately 9470) and the qualitative change in the nature of the material requiring final disposal, mean that scarce landfill resources can be conserved and the waste can be more easily dealt with. 4*10 The most significant of the disadvantages is the potential for air pollution. Measures that could be taken to reduce the pollution problem significantly fall into two broad categories namely - (i) those aimed at reducing the quantity of pollutants emitted from the plant; and (ii) those aimed at ensuring sufficient dispersal of pollutants so that receptors are not adversely affected; such measures can include siting of the facility as well as design. 4<. 11 The measures in category (i) include the installation of electrostatic precipitators to remove particulate matter and the installation of tfgas scrubbing1' equipment which aims to remove polluting gases. Gas scrubbing in particular is expensive and the technology is at a relatively early stage of development. In both cases, but especially in the case of gas scrubbers, further quantities of wastes may be produced which require subsequent disposal. Two out of the three Hong Kong incinerators possess electrostatic precipitators (the exception is Lai Chi Kok where electrostatic precipitators have been fitted to station A only). None possesses gas scrubbing equipments The efficiency of the electrostatic precipitators is generally in the range 94 to 99%. - D5 - 4-. 12 Enhanced dispersion and dilution of pollutants can be achieved by ensuring incinerators are built in areas where there is usually good air movement and little potential for emissions to become trapped close to ground level, and by building tall stacks. Unfortunately Hong Kong offers few opportunities for pollution from incinerators to be ameliorated in this manner. Much of the land suitable for constructing incinerators is in valleys where air pollutants are likely to be trapped. Over much of the remainder is a proliferation of high rise housing on which any effluent plume from a stack of 75 m or less is likely to impinge. Given the topography and building construction in Hong Kong it has been suggested that incinerator stacks should be as much as 200 m in height. Over much of Kowloon however, such a stack height would fall foul of airport flight path height restrictions which, over the Kowloon peninsula, range from about 45 m above PD to about 120 m above PD. Conceivably suitable sites could be found in the New Territories but construction of an incinerator at a site remote from the centre of waste arisings would result in considerably increased transportation costs. 4.13 To summarise, the advantages that incineration has to offer as a method of waste disposal mean that it must be seriously considered* However if it is to be used as a method of waste disposal in Hong Kong in the future, steps must be taken to ensure that the environmental impact is minimised. This would probably mean, at the very least, installing both electrostatic precipitators and gas scrubbing equipment. In addition it may be necessary to construct unusually high stacks to ensure adequate dispersal and dilution of flue gases and, possibly, to construct incinerators only in remote areas. The cost implications of these measures are such that if other alternatives are available they are likely, in most instances, to be preferred. (c) Transfer 4*14 Waste transfer is a waste treatment technique that effects virtuallyno reduction Inwastemass andis aimed primarily at reducing the costs of transporting waste to a point of final disposal. The concept involves the construction of a number of strategically - located transfer stations close to the centroids of waste arisings. Vehicles which have collected waste from the point of arising deliver it to a transfer station where it is transferred, with or without treatment, into a larger vehicle for haulage in bulk to a final disposal facility. The large vehicle may be a lorry, if road transport is utilised, or a barge if transport is to be by sea. A transfer station may include facilities for the compaction of waste to increase the payload of the bulk transfer vehicles. A further advantage of using a transfer station to treat waste prior to final disposal is that it provides the opportunity for waste to be containerised prior to haulage to a final disposal site. This would help to reduce considerably the problem of odour and dripping leachate during transportation. If direct discharge of waste to containers were to be adopted odour would also be reduced at the transfer station itself'. - D6 - 4'. 15 Transfer stations, like any other waste treatment or disposal facility, have the potential for generating a number of adverse environmental impacts. These include (i) traffic congestion; (ii) noise from generated traffic; (iii) plant operation noise; (iv) odour; (v) dust; (vi) polluted washwater and leachate production, and (vii) litter. The effects of these impacts can be reduced or eliminated by appropriate preventative and/or curative action. Proper planning and consideration of road capacities should ensure that a transfer station is not located in such a position,,, or constructed to such a size, as to give rise to significant traffic congestion. Plant and traffic noise can be kept to a minimum by ensuring that all vehicles and machinery are properly silenced and the plant is constructed according to stringent noise control standards* Dust can be kept to a minimum by ensuring that the plant is enclosed and that suitable barriers (such as rubber curtains) exist to prevent dust from the transfer operation escaping to the outside and causing a nuisance. Regular water spraying can also be carried out to keep dust levels down. Polluted washwater can be dealt with by provision of appropriate drain connections to a foul sewer. Litter and falling refuse could be kept under control by good housekeeping and by refusing to accept waste from private sector waste collection vehicles in which refuse was not properly contained. (Any such vehicles refused entry would have to go to a landfill to dispose of the waste. Appropriate enforcement measures would have to be implemented to ensure the waste was not dumped illegally). 4,16 The biggest potential problem with a refuse transfer station is probably that of odour. To control odour it would be necessary to operate a fully enclosed plant possibly with appropriate odour extraction systems'. It would also be necessary to ensure that vehicles arriving at or leaving the plant were not themselves a cause for complaint. This would mean requiring that all vehicles be washed regularly, both inside and out, and that all vehicles used for the collection of waste be of such a construction that the waste is properly enclosed. Apart from steps taken to control odour at source the most effective way to reduce the impact of odour would be to ensure the stations are not located close to residential areas. Other potential problems include bird nuisance and proliferation of vermin-* The former does not appear to be a problem in Hong Kong while efforts should be made to keep the latter under control by good housekeeping and conducting regular pest eradication exercise. 4* 17 Whether or not transfer stations are adopted as a method of waste treatment In Hong Kong depends upon (i) whether incineration is a viable option; and (ii) what the final disposal method is likely to be and where the final disposal sites are likely to be located. Disposalmethods 4.18 A means of final disposal of waste will always be necessary no matter what treatment and disposal strategy is adopted. If resource recovery or incineration were to be adopted there would have to be some way of getting rid of the residues remaining after treatment. For certain wastes, such as construction wastes, there ~\/ are few treatment options available and some means of final disposal .) : will always be necessary to cater for these. - •' 4.19 The two main advantages of landfill as a means of final disposal are (i) that it can be used for almost every type of waste; and (ii) that it is relatively cheap. 4.20 The main problems associated with the use of landfill as a means of final waste disposal have already been described in Appendix C in relation to existing Hong Kong landfills. If advantage is to be taken of the relatively low cost of landfill as a disposal method it is important that steps should be taken to reduce odour to an acceptable level and contain and control any gas or leachate generated. It is also important to ensure that the land can be put to reasonably productive use shortly-^af t erJuh&_jsi.tei s exhausted. 4.21 To summarise, the continued use of landfill as an option for disposal of Hong Kong's waste is feasible and desirable. However any future landfills established must include measures to ensure that odour and uneven settlement are minimised and gas and leachate production are properly controlled. The cost of including these measures need to be considered when formulating a definitive waste disposal strategy. (b) Dumping at sea 4.22 Dumping of waste at sea is a very simple method of disposal as it involves little or no treatment of the waste. D8 - In practice, however, it can be considered acceptable only for a limited number of waste types. Any waste which might float (e.g. domestic waste with paper and plastics, building wastes containing wood) cannot be dumped at sea because of the aesthetic effects and the navigational hazards that would arise. Neither can waste which would sink, but which would introduce significant quantities of toxic substances into the marine environment'. Sea dumping is, in effect, suitable only for the disposal of :- (a) material that sinks, is non-toxic and will not present a hazard to shipping; and (b) material that is non-toxic and will dissolve and disperse readily in sea water. In other words sea dumping is a feasible disposal option only for sludges, excavated and dredged soils and certain soluble chemicals. (c) Discharge to coastal waters 4.23 This method of disposal involves the pumping of wastes down pipelines running from the point of arising on shore to a distance up to several kilometres off shore. It can only be used for semi-solid or liquid wastes. In the context of the waste disposal plan this means sewage and water works sludges and chemical wastes which happen to be liquids or sludges. These wastes are considered in later paragraphs. 4.24 To summarise, it is concluded that for municipal wastes disposed of by the public sector only those treatment and disposal methods which do not incorporate a substantial element of resource recovery should be adopted* For household, commercial and industrial waste, this effectively means that treatment is limited to incineration and/or transfer, and final disposal to disposal at a landfill. Construction waste, is not suitable for treatment by incineration or transfer'. Nor is it suitable for final disposal by dumping at sea. It is clear therefore that for the majority of Hong Kong's waste the only feasible final disposal method is disposal to landfill. Incineration and transfer may also be used to conserve landfill resources and/or reduce transportation costs , the precise balance of' facilities dependin' g up the balance of ' costs' and DIFFICULT WASTE 4.25 For the "difficult" waste,, possible treatment and disposal methods are somewhat more varied* It therefore needs to be considered on a type-by-type basis. - D9 - Sewage sludge 4.26 Options available for the treatment or disposal of sewage sludge are (i) landfill; (ii) sea dumping; (iii) discharge down a long sea outfall; (iv) incineration; and (v) use as a fertiliser. 4 (a) the relatively limited amount of land under agriculture could not absorb a sufficient quantity of the sludge produced; and (b) the vegetable growers in Hong Kong typically need a multiplicity of fertilisers for different vegetables grown in different seasons and sewage sludge would not be a good fertiliser for use in this context'. There is also the potential problem of contamination of soils by heavy metals, some of which are found in relatively high concentrations in Hong Kong's sewage sludge. This leaves landfill, incineration and sea dumping as possible disposal options. 4.28 A comparison of the costs of these three options has indicated that for sludge arising at treatment works which are in close proximity to moderately deep water sea frontage, dumping at sea is about 60% cheaper than dewatering followed by disposal at landfill, which is in turn about half the cost of dewatering followed by incineration. On the basis of this cost comparison and a subsequent detailed feasibility study by consultants it has been concluded that action should be taken immediately to arrange for the disposal at sea of all stabilised sewage sludges generated at the Sha Tin Sewage Treatment Works, with the option of extending this disposal plan at a later date to sludges arising in Tai Po and North Districts. 4'.29 Disposal of sludge at sea is not without environmental problems* Possible adverse effects include promotion of algal blooms, deoxygenation of the water column, increased turbidity, smothering of the sea bed and accumulation of persistent pollutants (such as heavy metals and some non-degradable organic compounds) in marine food chains* However the site selected as the dumping ground - DIG - has good dispersal characteristics and there is no reason to believe that the assimilative and dispersive capacity of the area will be exceeded by the dumping of sludge at the quantities proposed. As a safeguard against the possibility that the dumping programme might have adverse effects the government has established a comprehensive environmental monitoring programme. A major baseline study of the physical, chemical and biological characteristics of the area is currently being carried out. There will be a limited survey in 1991 and further comprehensive surveys will be carried out in subsequent yearsv The environmental effects will thus be monitored regularly and a major review will be conducted after five years1 operation with a view to deciding whether dumping should be allowed to continue and, if so, whether the quantities dumped could be increased so that sludges from Tai Po and North districts could be included. 4.30 For sewage sludges arising in areas not in close proximity to a suitable waterfront, disposal will have to be to landfill. The sludge will first have to be dewatered and disposal carried out in such a way that it will not produce operational difficulties at the landfill or localised leachate, gas, and settlement problems. Prior experimentation will be necessary to determine the best way of mixing sludge with other refuse in order to avoid these problems. Water works sludge 4.31 Water works sludge is completely different in character from sewage sludge. It arises from the use of alum as a coagulant to remove fine silt, chemical residues and organic material from potentially potable water and is consequently a gelatinous, relatively inert and incombustible material with a very low (1%) solids content and low concentrations of organic material. It contains relatively high concentration of aluminium, iron and manganese. 4.32 Options for disposal of water works sludge are limited to dumping at sea or discharge to coastal waters via a long sea outfall* Since a decision has been made to dump Sha Tin's sewage sludge at sea it Is Intended that Sha Tin's water works sludge should be disposed of in a similar manner. As with sewage sludges, the possibility of disposing of alum sludge from Tai Po and North districts In the same way will be reviewed at a later date. Improved methods of dealing with water works sludges In other areas have not yet been worked out. This problem will need to be addressed separately. Sewage treatment works screenings and grit ;: , ••• 4.33 These wastes are currently disposed of at landfill. The quantities Involved are very small In comparison with the quantities of other wastes that will continue to require disposal to landfill and it is therefore not proposed that future arrangements for disposal should differ froro those now employed*. - Dll - Excrestental waste 4.34 These wastes are presently mainly delivered to sewage treatment works for treatment and digestions They therefore are, and will continue to be, disposed of by whatever method is used for sewage treatment works sludges. In particular excremental wastes delivered to Sha Tin sewage treatment works for digestion will eventually be disposed of at sea. Livestock waste 4*.35 When livestock waste is brought under control arisings requiring disposal will be in two forms namely sludge and raw manure. However the installation by farmers of facilities for the dewatering of sludge and the deposit of the sludge at a government collection point is likely to be cheaper than having the raw sludge collected and removed by a contractor. It is therefore anticipated that most of the sludge would be removed by the government's collection service. In view of the relatively small quantities of arisings of sludge that are projected compared with those of dry muck out waste and the fact that the moisture content of the two types of waste will be roughly the same (8570) it would be sensible to dispose of the two types of waste together and disposal options are considered on this basis. 4^.36 The options for disposal are :- i) digestion at sewage treatment works with sewage sludges; ii) disposal to land (i.e. used as a fertiliser); iii) disposal at landfill; iv) disposal at sea; and v) incinerations Incineration has to be discounted because it is too expensive. Disposal at sea would not be economic on its own but following the decision to construct facilities for the disposal of Sha Tin's sewage treatment works sludge at sea it may well be feasible to dispose of some livestock waste by this route also, provided it is stablised first, Further consideration has still to be given to this possibility, and to the possibility of disposing of the wastes by digestion at sewage treatment works. Disposal at landfill is also possible subject to appropriate loading rates being worked out. Research into this latter aspect is currently being conducted by the Environmental Protection Department. - D12 - 4.37 Notwithstanding the fact that other options are feasible the preferred option for disposal of livestock wastes is to land, by use as a fertiliser- For use as fertiliser the wastes will have to be composted (although farmers following the wet muck out method who do not wish to use the government collection service might conceivably dispose of some sludge by direct application to land). The choice of composting as a means of disposal has the added benefit that the process involves stabilisation of the waste, which would be necessary if outlets for compost could not be found and landfill or dumping at sea had to be adopted. 4.38 The possibility of the government being involved in the composting of livestock waste appears to run counter to the general principle that the public sector should not adopt treatment or disposal methods which result in the production of a material that needs to be marketed and sold as a commercial product* However in this particular instance government involvement is justified. The control of livestock waste disposal is essential. Livestock waste has considerable potential as a recovered resource in the form of compost as fertiliser. Yet it is unlikely that individual farmers would have the necessary expertise to develop appropriate composting techniques or to develop the necessary market for the product. By taking the lead the government may be able (i) to control the waste; (ii) to recover a valuable resource; and (iii) to develop a means of waste recovery that will enable farmers to recover some of the costs of waste control. 4*39 There remains the possibility however that outlets for composted manure will not be found and all the waste, whether fully or partially composted, will need to be disposed of to landfill* .Condemned goods,, abattoir- waste and animal carcasses 4.40 For those condemned goods which are in a packaged or Incombustible form (e.g. tinned food), landfill is the only feasible method of disposal. For those condemned goods which are not packaged and which give rise to a health risk (e,g. thawed meat), incineration is preferable but incineration in this context means cremation i.e* incineration in a long residence time combustion chamber. Incineration in an incinerator designed for refuse would not be appropriate because the relatively short residence time would be 1ikely to lead to incomplet e combus t ion * Cremation is a1so required for animal carcasses* At present bad meat and a proportion of the animal carcasses are cremated at the incinerator at Kennedy Town abattoir. Carcasses collected by the Regional Services Department are disposed of at landfills* - D13 - The latter method of disposal is not satisfactory and carries health risks as well as being generally offensive^ It is currently carried out only on a temporary basis. On the other hand the abattoir incinerators were designed to cater only for the destruction of any diseased animals brought in for slaughter and were not intended to serve as a general facility for the disposal of carcasses of farm animals and pets. Consequently it would not be appropriate or possible to use the abattoir incinerators for this purpose on a long term basis. 4.41 Reprocessing at by-product plant is also a possible option, in particular for the large arising of abattoir waste. Abattoir waste which cannot be economically reprocessed is difficult to handle due partly to its offensive nature. Incineration is feasible but special arrangements would be required to allow some dewatering prior to incineration and to facilitate handling* In view of the relatively small quantities of waste generated such facilities cannot be justified and disposal to landfill is therefore the most appropriate option for the future. OTHER WASTES Dredged and excavated wastes 4^.42 There are only two alternatives for the disposal of these wastes viz : (i) landfill; and (ii) disposal at sea. Very large quantities of these materials are produced each year which, if disposed of to landfill, would result in a greatly accelerated depletion of landfill capacity and considerable leachate problems. In addition, as much of the material is dredged from the sea bed, transferring it to land would serve little useful purpose but would incur substantial additional expense. The preferred option for disposal of these wastes is therefore marine dumping. Clinical waste 4.43 Clinical waste should ideally be incinerated in purpose-built incinerators in order to safeguard public health* Incineration in municipal incinerators is not appropriate because of the danger of incomplete combustion* All future planned hospitals, whether in the public or private sector> should therefore incorporate incinerators with adequate capacity to deal with the wastes produced. The incinerators should be capable of achieving complete combustion of material. It is recommended that for public and private hospitals and clinics whose incineration capacity is inadequate, the clinical waste should be collected and disposed of at a centralised facility, which could incorporate a cremator for handling animal carcasses* 'Facility1 in this context could mean a single plant with combustion chambers designed for different waste or designed to operate under varying conditions'. - D14 - Chemical waste 4.44 A wide variety of chemical wastes are generated in Hong Kong and it is difficult, if not impossible, to recommend a single disposal method that would be suitable for all of them* Broadly the options are as follows i) dumping at sea, uncontained; ii) dumping at sea, contained; iii) disposal to containment site on land; iv) codisposal at ordinary landfill; v) recovery and reuse; vi) chemical treatment prior to disposal at landfill; and vii) high temperature incinerations 4.45 Straightforward dumping at sea is unacceptable because it would mean the direct introduction of toxic material into the marine environment and would be no improvement on the present situation. Option (ii) might be a possibility for some chemical wastes. The wastes could be sealed in impermeable, corrosion-proof and shockproof containers and dumped off the edge of the continental shelf. This option would be extremely expensive and would always carry the danger that containers could be dispersed from the original dump sites by ocean currents into areas where they could pose a hazard to navigation or fishing-. In addition if containers were to leak it would be impossible to control the resultant pollution. 4*46 Option (iii), disposal to a containment site on land, would involve placement of the wastes in a specially-designed site isolated from the environment by liners and an impervious cover. This is essentially a method of waste storage and little degradation of the waste could be expected to take place'-. The site would require long-term monitoring, maintenance and supervision, and stringent security to keep members of the public away; In all probability the site could never be put to any beneficial use once the disposal capacity was exhausted-*. This is therefore not a preferred option. 4.47 Codisposal to landfill is feasible* This would involve the disposal of chemical wastes at ordinary landfills receiving municipal wastes. At a codisposal site various natural physical, chemical and biological processes act to detoxify the chemical wastes so that the impact on the environment is practically the same as that of a landfill receiving only municipal wastes. The problem with codisposal is that adequate detoxification depends on mixing a small volume of hazardous waste with a large volume of municipal waste* - D15 There is also the added problem that different types of chemical waste would need to be kept well separated from each other at the codisposal site, further reducing codisposal capacity. Because of these problems it has been decided that codisposal should not be adopted as a general solution for the disposal of all hazardous wastes but should only be used for the disposal of wastes for which other means of disposal (e.g. recovery and reuse; chemical treatment, incineration) are inappropriate. 4.48 Recovery and re-use of some chemicals, chemical treatment of others and incineration of others are feasible. In view of the need to conserve codisposal capacity it has been decided to establish a chemical waste treatment centre on Tsing Yi Island incorporating all these treatment methods. After treatment there would remain a need to dispose of residues. These would be disposed of at landfills by mixing with municipal waste. Studies are now in hand to establish the mixing ratios necessary to obtain the complete attenuation of any chemical wastes deposited at a codisposal site. Radioactive waste 4.49 Existing methods of disposal of radioactive wastes are generally adequate. There is a possibility that some wastes currently disposed of by storage underground could be dealt with by codisposal at a landfills This may allow for the establishment of a smaller, purpose-built, long term storage chamber. A separate study has been initiated to investigate these possibilities. PFA and FBA 4.50 In addition to the current methods of disposal of PFA and FBA (ive. lagooningy and sale on a commercial basis) the other options for disposal are (a) disposal at sea; (b) land restoration (for example, old quarry); and (c). reclamation'. Disposal at sea is not a favoured option for three reasons. First, a proportion of PFA consists of vitrified, hollow spheres which will float and which may hence produce a problem of pollution of surficial waters Second, when deposited in bulk in seawater physico-chemical reactions lead to the formation of amorphous "concrete11 lumps. - D16 - If these were to accumulate on the sea bed they could present a navigational and fishing hazard. Third, PFA and FBA are relatively rich in concentrations of potentially toxic heavy metals. Deposit of these in a concentrated manner on the sea bed may pose a threat to marine life and, through possible concentration through the food chain, a threat to public health. 4.51 Land restoration and reclamation are potentially useful methods of disposal but it is as yet unclear whether they are both feasible and practical. Studies are currently under way to examine both feasibility and practicality. 4.52 Existing methods of disposal are proven. Lagooning is successful and will continue to be used in the future. Sale of PFA and FBA on a commercial basis is the preferred option but it is questionable whether sufficient outlets can be found to accommodate the projected future increase in production. 4.53 To summarise, the preferred option for disposal of PFA and FBA is sale on a commercial basis, followed by lagooning if sale outlets cannot be found. Use of PFA and FBA in land restoration and reclamation is to be investigated as a possible long-term solution to the disposal problem^ - El - APPENDIX E THE WASTE MANAGEMENT MODEL (WMM) 5'. 1 The Waste Management Model (WMM) is a computer-based planning aid employed to develop a cost effective waste management plan-* 5*2 The WMM consists of the following interactive sub-models/data bases: (a) Waste arisings sub-model: calculates all existing and projected future waste arisings by type and geographical area. (b) Transport network sub-model: calculates average journey times and distances between waste sources, treatment plants, disposal facilities, vehicle depots etc. using a simplified principal road network; different road networks for different planning years, based on existing development plans, are stored in the sub-modelv (c) Transport cost sub-model: calculates transport costs associated with various transport methods and equipment using output from the transport network sub-model and data on the capital and operating costs of waste-collection vehicles, including barges and private contractors' vehicles. (d) Facility cost data base: contains cost data for the construction of existing and potential facilities (e.g. incinerators, landfill sites, transfer stations) and their operation at a number of feasible capacities. (e) Allocation sub-model: allocates wastes to facilities at minimum cost, either in total or, if required, at minimum cost to a specific sector (e.g. Urban Council and Regional Council costs, private contractor costs). (f) Strategy assessment sub-model: summarises the cost implications of a particular strategy for each of the agencies involved in waste management (USD, RSD, EMSD, CESD, private sector etc*). (g) Plan evaluation sub-model: evaluates the total costs of the selected strategies over the full planning period. 5t3. it should be noted that in order for the computations to be carried out it is necessary for the user to specify which facilities are available and also to define the time period under study. An outline of the way a run on the model is conducted in order to arrive at a costing for a particular strategy will make this clearer. - E2 - 5-. 4 The user first defines the time scale over which the calculations are to be made, say 15 years, and divides the time scale into a number of shorter time periods (say, 2 years each) to allow for more flexibility in strategy selection. He also selects the type(s) of waste under consideration and one of a number of forecasts for future population and employment in Hong Kong, on the basis of which projections of future waste arisings are to be calculated. The model then computes the quantities of wastes of the selected type that are predicted to arise in each of the selected time periods for a number of pre-defined source areas, based on the forecast population and employment statistics* 5.5 The user then specifies, for each time period, the existing and potential facilities (i.e. transfer stations, other treatment plants, final disposal sites and refuse collection vehicle depots). The model calculates the costs of transporting each type of waste from source areas and facilities to each destination by the appropriate means of transport* Also calculated are the costs of processing or disposing of waste at each specified facility, taking into account both capital and operating costs'. The model then calculates, for each time period, how best to assign wastes from the source areas to the facilities available so as to minimise the cost to one or more sectors. 5.6 The user must then assess the configuration proposed by the model* In doing so he will wish to consider the feasibility of the proposed configuration, especially in relation to possible environmental impacts'. He may also wish to investigate how the recommended configuration would change if the economic and financial variables were altered (evg. population and employment projections, transport costs). 5.7 The user may also assess other strategies by changing the specifications of facilities available in each time period. For example he may alter the maximum or minimum treatment capacity of an incinerator or transfer station. ¥hen a number of other strategies have been assessed, and comparisons made, the user eventually arrives at a strategy which is cost-effective, feasible and environmentally acceptable, the costs of which are relatively insensitive to moderate variations in the assumptions. (It must be emphasised however that the costs of the different strategies generated by the model are primarily for comparative purposes and cannot be considered as accurate predictions of the actual costs for any particular strategy), 5*8 The WMM has been employed in examining options for the future provision of transfer stations in combination with the final disposal facilities-. Restrictions applying to the modelling exercise are :- (a) Projections of future waste arisings - Projections of future population on a geographical basis (i.e. district by district) are at present available only upto the year 2001. - E3 - Consequently It has not been possible to compute detailed district-by-dlstrict projections of waste arisings after 2001 on which to base provision of treatment facilities. The model has therefore been used to examine options for dealing with Hong Kong's waste only upto 2001. (b) Site availability - Firm sites for transfer stations have not been identified in all areas where they might be required. For options which involve the construction of transfer stations in areas where sites have not been identified it has been necessary to presume that sites in the general area will be found at some time in the future. (c) Site capacity - The difficulty of obtaining suitable sites means that there is only limited flexibility as to the capacities of the treatment facilities and the timing of their construction* Capacity is limited by site size and road access, and the timing of construction is determined as much by when the site becomes available as by the projected need for additional capacity. - Fl - APPENDIX F ESTIMATED CAPITAL AND RECURRENT COSTS OF PROPOSED MAJOR WASTE MANAGEMENT FACILITIES Average Capital Cost Recurrent Cost Project $ million $ million p*a« Kowloon Bay Transfer Station 152 35 Island East Transfer Station 183 38 Island West Transfer Station 106 19 Shatin Transfer Station 82 19 Yuen Long Transfer Station 60 15 West Kowloon Transfer Station 144 20 West New Territories Landfill 1308 35 North-east New Territories Landfill 1407 35 South-east New Territories Landfill 1364 35 C Chemical Waste Treatment Centre 410 Centralised Incineration Facility 2.4 for Special Wastes Total 4830 664 Footnote : a'\inclusive of capital cost repayment over a 15 year period 0> JB, co o ^2- — "^ " i ^ o> O"O 1 x SJ ...... l.|i| 1 s~ §/• i1?® N^ CD " ''? cb'SS-" CO 2 2f CO* —* cr 'X 1 ill S~ Q. SJ o --. '••-.. O fs - x D 0 - .§'-" ^ O •••*•" "••• • '••. tr § ,~ ^.. CQ . : . .., 0 'X. • i- - B16 -