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TRP Chapter 6.6 1 Chapter 6.6 Land disposal. TRP Chapter 6.6 2 Structure of chapter Introduction Part A: Key principles of a landfill site Part B: Handling.

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Presentation on theme: "TRP Chapter 6.6 1 Chapter 6.6 Land disposal. TRP Chapter 6.6 2 Structure of chapter Introduction Part A: Key principles of a landfill site Part B: Handling."— Presentation transcript:

1 TRP Chapter Chapter 6.6 Land disposal

2 TRP Chapter Structure of chapter Introduction Part A: Key principles of a landfill site Part B: Handling industrial wastes in municipal landfills as an interim solution - Co-disposal Part C: Purpose-designed industrial waste landfill sites

3 TRP Chapter Introduction: Current status of landfill  Many industrialising countries are still practising open dumping  Uncontrolled disposal of hazardous waste on municipal and sanitary landfills  Many sites are unlined, with little management of landfill gas or treatment of leachate  Poor operational standards of sites poses threats to public health and environment Short term priorities: to raise standards eliminate uncontrolled dumping Long term: some land disposal will still be needed

4 TRP Chapter Risks of uncontrolled landfill Leachate leakage into groundwater or rivers Contaminated surface water run-off into soil, watercourses Uncontrolled burning Gas migration into soil and air Landslip of unstable wastes Flies and vermin Dust and odours Poor disposal practices can cause: harm to human health - workers, site neighbours and scavengers damage to flora explosions and fires

5 TRP Chapter Risk mitigation Measures to mitigate risks include: prohibition of certain wastes proper site selection waste compaction and daily cover landfill liners gas & leachate collection/treatment design & engineering to control waste deposition, water ingress

6 TRP Chapter Uncontrolled landfill: landslip Payatas dumpsite, Philippines 2000 Source:

7 TRP Chapter Need to raise standards Chemical fire on European dump site example of the risks of mixing hazardous wastes with MSW Source: David C Wilson

8 TRP Chapter Part A: Key principles of a landfill site

9 TRP Chapter Stages in improving landfills Open dump Semi controlled landfill Designated dump Sanitary landfill No controls Dumping kept within designated area; no control over operation Site supervised; controls over wastes accepted/ waste placement; periodic waste cover Engineering & operational control measures in place Industrial waste landfill

10 TRP Chapter Components of a well-managed landfill operation  Well chosen, properly designed site  Bottom liner - to protect soil and groundwater  Leachate collection and treatment - to prevent contamination of groundwater  Gas management - to prevent damage to soil and escape to air  Waste placement in cells - for operational control and to reduce rainfall infiltration  Waste compaction - to limit access by vermin and to reduce risk of fires  Daily and intermediate cover  Final cover

11 TRP Chapter Choosing a site In a depression - preferred On level ground On a slope

12 TRP Chapter Improving municipal landfill practice: site considerations Need to take into account: geological & hydrological characteristics eg drinking water sources in vicinity, areas liable to flooding or erosion proximity to urban areas Preferred sites may include: sites containing thick clay layer sites above unusable groundwater

13 TRP Chapter Siting a landfill: example Suitable for site with:  level land surface  low groundwater table  soil layer thicker than 2 metres Solid waste management for economically developing countries, ISWA, 1996

14 TRP Chapter Site design - liner systems  Single liner  Clay or synthetic liner  Composite or double lined  One clay liner and one synthetic liner  Two synthethetic liners Liner selection criteria:  Cost  Local geology and hydrogeology  Availability of appropriate materials  Desired degree of protection against leachate escape  Liner durability

15 TRP Chapter Site design - liner materials Natural lining materials Synthetic lining materials Clay Polyethylene Bentonite liners - HDPE Pulverised Fuel Ash (PFA) - LDPE Polyvinyl chlorine (PVC) Chlorinated polyethylene

16 TRP Chapter Cross-section of multiple liner system Geotextile filter Stone/ gravel layer Primary geomembrane layer Primary and secondary leachate collection piping Secondary geomembrane layer Secondary leachate collection layer acts as leak detection Compacted clay

17 TRP Chapter Drainage pipes in a composite liner system Source: Landfill of hazardous wastes, Technical report No 17, UNEP Site design - leachate control

18 TRP Chapter Site design - landfill gas management Gas components Typical values %Risks Methane 63.8Explosion Carbon dioxide 33.6Asphyxiation Nitrogen 2.4 Oxygen 0.16 Fire Hydrogen 0.05 Other trace gases Toxicity Gas monitoring by: surface and sub-surface monitoring excavated pits boreholes and wells Gas end uses: Fuel eg in vehicles, boilers, kilns & furnaces Power eg gas turbines, diesel engines

19 TRP Chapter Site preparation Fencing to control access

20 TRP Chapter Site operation Key factors: Waste placement in cells Waste compaction Daily and intermediate cover Final cover

21 TRP Chapter Cellular structure Source: ISWA, Solid waste management for economically developing countries, 1996

22 TRP Chapter Waste compaction Maximises void space Reduces risk of fires in waste Deters vermin

23 TRP Chapter Purpose of cover  Improves site appearance  Minimises wind-blown litter  Reduces landfill odours  Inhibits colonisation by vermin & vectors  Reduces rainwater infiltration thus reducing leachate  Controls gas and leachate migration  Reduces soil erosion

24 TRP Chapter Final cover Vegetation Top cover Drainage layer Clay layer Aims: to stabilise site improve its appearance enable post- closure use Final cover must be: durable flexible weather resistant regularly inspected & maintained

25 TRP Chapter Completed landfill - cross section

26 TRP Chapter Part B: Handling industrial wastes in municipal landfills as an interim solution - Co-disposal

27 TRP Chapter Basic requirements for co-disposal Control the waste that comes in require pretreatment of some wastes exclude some wastes eg flammable liquids test wastes keep detailed records Improve waste reception and handling systems Employ skilled, trained staff

28 TRP Chapter Testing and record keeping Important to know what is being handled A testing and record keeping regime should be introduced when upgrading an existing site or starting a new one Enables detailed tracking of wastes from point of generation to location in completed site Hazardous wastes should be tested: prior to acceptance to ensure appropriate disposal and waste compatibility again on delivery to verify composition Waste details must be recorded and records stored safely Records should provide: details of sources - waste generator, transport contractor composition, form and quantity of wastes date of placement exact location in site

29 TRP Chapter Compatibility of hazardous wastes One of the reasons for upgrading is to reduce the potential for harm from the uncontrolled mixing of incompatible hazardous wastes

30 TRP Chapter Co-disposal Co-disposal is the disposal of selected hazardous wastes with other heterogeneous wastes such as biodegradable municipal solid waste, industrial & commercial wastes it takes place in properly managed sanitary landfill it is a highly skilled and technically controlled operation it is suitable for selected solid and sludge wastes at controlled rates of application it uses the physical, chemical and biological processes within an MSW landfill to ‘treat’ hazardous constituents it is not the same as uncontrolled mixing of hazardous wastes and MSW

31 TRP Chapter Co-disposal - considerations & status Co-disposal needs great care because: –both hazardous wastes and MSW are variable and complex –it is difficult to predict chemical & biological reactions Co-disposal:  has been discredited by uncontrolled past practice  has been widely practised in parts of Europe eg UK  is being phased out under EU Landfill Directive requirements  is worth considering as short-medium term option  is better than uncontrolled disposal

32 TRP Chapter Wastes suitable for co-disposal  Bottom ash from waste incineration  Contaminated soils  Heavy metal hydroxides (pH > 8)  Slag, bitumen waste  Oil sludges, paint sludges, tannery sludges  AVOID aqueous wastes, bulk liquid wastes  AVOID mixing incompatible wastes  CHECK wastes compatible with liner material

33 TRP Chapter Co-disposal - maximum concentrations Waste Concentration Acid wastes 0.1m3 acid / tonne of MSW Heavy metals waste 100g soluble chromium, copper, lead, arsenic, nickel or zinc /tonne of MSW 10g cadmium / tonne of MSW 2g soluble mercury / tonne of MSW Phenolic wastes 2kg of total phenols / tonne of MSW Cyanide wastes 1g/ tonne of MSW Total organic carbon 5kg / tonne of MSW Oil, grease and 2.5 kg waste/ tonne of MSW hydrocarbon wastes Source: World Bank Technical paper 93

34 TRP Chapter Components of a well-managed co-disposal operation  A continuing supply of municipal waste  Trained operational manager and staff  Sufficient mobile equipment for site preparation  No scavenging should be permitted  No direct burning of waste on site  Ensure only suitable waste types are deposited - need to test all wastes prior to acceptance  Check and record waste types and their origin at the site entrance  Supervised disposal at landfill face or in trenches or pits dug into MSW at least 6 months old  Regular inspections on site

35 TRP Chapter Co-disposal site infrastructure 1 Separate areas of landfill should used for different hazardous waste types Roadways should be clearly signposted Trenches should be clearly marked and fenced Wheel cleaners should be provided for vehicle entrance and exit Laboratory facilities should be available on site for simple analysis Holding area is needed for lorries to be checked Storage area

36 TRP Chapter Co-disposal site infrastructure 2 Source: World Bank Technical Paper No 93 Area for future co-disposal in trenches

37 TRP Chapter Hazardous waste placement - practicalities At landfill face: suitable only for small quantities of solid waste Trenches or pits dug into MSW: MSW at least 6 months old thick layer of MSW below pit cover after deposit for particuarly difficult wastes, seal pit after each deposit all operations must be supervised

38 TRP Chapter Co-disposal case study Asbestos waste Aim: Containment, preventing human contact with, or airborne release of, asbestos Process: All wastes must be delivered in double-wrapped, sealed bags or containers No mechanical handling or compaction which may damage containment Pits should be excavated in advance Bags/containers should be placed into pit Pit covered and sealed immediately Location recorded to prevent future re-excavation

39 TRP Chapter Part C: Purpose-designed industrial waste landfill sites

40 TRP Chapter Option 1: multi-disposal Requires secure landfill site dedicated to disposal of hazardous waste Site must be: Highly engineered Have discrete cells for different waste types, separated by barriers Designed to: resist leakage segregate incompatible wastes contain waste in a safe manner prohibit contact between landfill contents and surrounding environment Method commonly used in USA

41 TRP Chapter Wastes suitable for disposal in multi-disposal site Drummed and bulky solids Pretreated sludges Metal-finishing wastes eg lead-, chromium-, copper- and nickel-bearing wastes Contaminated soils Incinerator ash

42 TRP Chapter Multi-disposal site design Source: Hazardous wastes, sources, pathways, receptors, Richard J. Watts, 1997

43 TRP Chapter Multi-disposal site operation  Check waste compatibility  Control types of HW waste to be buried  Place chemical HW in groups of stacked containers  Separate cells from each other by fill  Record different HW types and their origin  Devise emergency plan for spills and accidents  Require the use of heavy machinery  Provide training for all personnel  Ensure health and safety of operators

44 TRP Chapter Source ??? Section through multi-disposal site

45 TRP Chapter Option 2: Secure landfill of stabilised wastes  Driven by regulations  Accepts only cement-stabilised wastes, possibly certain other solid wastes  Simplifies management  Enables higher level of regulatory control Standard practice in EU and increasingly in other countries

46 TRP Chapter Basic principles of secure landfill of stabilised wastes Similar to sanitary landfill: engineered, lined, top cover cellular design/layout Each cell filled with stabilised waste Examples of secure landfill for stabilised hazardous waste include: Ratchaburi secure landfill, Thailand  Capacity 100,000 tonnes of HW  Shenzhen secure landfill, China  Capacity 23,000 cubic metres of HW

47 TRP Chapter Adaptation of secure landfill of stabilised hazardous wastes Relies on structural properties of stabilised waste Cement-stabilised wastes built up either in discrete blocks or monolithic ‘celluar hills’ Each batch left for a period to monitor structural strength before continuing to build the landfill

48 TRP Chapter Option 3: The ‘ultimate’ landfill Consists of: lined concrete basin movable roof wastes placed by overhead crane may accept a variety of solid wastes each cell topped by concrete Pictures show AVR site in The Netherlands

49 TRP Chapter Chapter 6.6 Summary Need to control landfill, to mitigate risks - open dumping not acceptable Stages in upgrading and design, and operational standards necessary Co-disposal as an interim solution - requires good management, skilled staff Purpose-designed landfill for hazardous wastes

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