WASTE DISPOSAL What is waste? Who monitors and controls the disposal of waste? How is it disposed of? Disposal of waste to landfill
WHAT IS WASTE? Waste is rubbish people at home and work discard because they no longer need it. England and Wales produce 400 million tonnes of waste every year. Careful management is needed so its effect on the environment and human health is minimal.
TYPES OF WASTE Controlled Waste –Household, industrial and commercial waste –May be classified further as: Inert Non-Hazardous Hazardous Non-controlled Waste –Agricultural, mining and quarry waste
THE ENVIRONMENT AGENCYS ROLE The EA regulates waste management through a system of licences (PPC Permits). The EA waste team is responsible for ensuring that waste produced in England and Wales is correctly disposed of, in a manner that minimises its impact on people and the environment.
THE ENVIRONMENT AGENCYS ROLE (Cont.) They do this by: –advising on waste management methods including waste minimisation; –issuing Permits to waste operators providing satisfactory controls are in place; –site inspections and enforcement; –registering and monitoring people who transport waste; –working closely with other organisations to tackle specific issues such as fly-tipping (dumping waste illegally).
THE ENVIRONMENT AGENCYS ROLE (Cont.) The EA carries out site inspections periodically to make sure that waste is recovered or disposed of in ways that do not harm the environment or cause damage to human health. If the Agency finds evidence that the environment or public health is placed at risk, they can take the action needed to prevent or reduce the risk.
HOW DO WE DISPOSE OF WASTE? Around 70% of controlled waste in the UK is sent to landfill. The dots on the map indicate the location of active landfill sites in the UK.
HOW DO WE DISPOSE OF WASTE? New legislation has recently been introduced in the UK. The EU Landfill Directive introduces some new requirements that will fundamentally change the way we manage waste in the UK & Europe. It aims to classify landfill sites across the whole of Europe and to regulate them in a more coherent and consistent manner.
HOW DO WE DISPOSE OF WASTE? (Cont.) Some new requirements introduced by the Directive include: –reducing the quantities of biodegradable municipal solid waste (MSW) sent to landfill; –banning the disposal of certain types of waste (clinical, liquid, explosive, corrosive, oxidising, flammable, highly flammable waste and tyres); –treating most wastes before landfilling; –more prescriptive engineering standards.
HOW DO WE DISPOSE OF WASTE? (Cont.) Some other ways of disposing of or minimising waste include: –Recycling –Composting –Incineration
DISPOSAL OF WASTE TO LANDFILL An understanding of Geology is fundamental to the management of waste because: –Wastes and contaminants occur in and travel through the geologic environment so we need to understand: the nature of this environment the transport processes –most waste management schemes involve the use of geologic reservoirs for containment or the use of geologic process for dilution and dispersal of the waste
Modern landfills are designed to confine the waste to prevent it from causing environmental or health problems. Daily cover is placed over the compacted waste each day to minimise infiltration of rainwater.
WHAT PROBLEMS DO LANDFILL SITES POSE? Groundwater Contamination Production of Landfill Gas Landfill fires Offensive odours Litter Pests (Vermin, seagulls, flies) Increased traffic for duration of infilling Long term settlement after completion
GROUNDWATER CONTAMINATION Groundwater contamination can occur if leachate leaks into the soils and rock surrounding a landfill site, eventually making its way to the water table and contaminating the groundwater. Leachate is formed when water percolates through solid waste. Leachate can be highly toxic.
PRODUCTION OF LANDFILL GAS Landfill gas is produced during the natural breakdown of biodegradable waste. The composition of landfill gas changes over time. The gas from a typical landfill site consists mostly of methane and carbon dioxide.
LANDFILL FIRES As waste decomposes it generates heat and underground fires may start. These are difficult to extinguish, may last for long periods, and may spread throughout the landfill.
LANDFILL DESIGN Modern landfills are designed to minimise these problems: –Location –Landfill Liner –Compaction of waste –Daily Cover –Landfill Cap –Leachate Management System –Landfill Gas management System
LANDFILL LOCATION In order to obtain a permit a landfill operator must first carry out a detailed investigation and prove to the satisfaction of the planning authority and the EA that the site: –is located in a geologically stable area –is not located on a major aquifer; –Is not located in a vulnerable area; –is designed to reduce the risk of damage to the environment and human health; –will be monitored regularly for the duration of operations and aftercare period.
Installation of monitoring/site investigation borehole
LANDFILL LINERS Landfill Liners are constructed on the base and sides of a landfill site to prevent leachate from leaking into the surrounding soils. Landfill Liners may be constructed from: –Compacted Clay –Bentonite Enhanced Sand –Geomembrane –Geotextile Protector –Dense Asphaltic Concrete (DAC) –Combination of the above
LANDFILL LINERS Construction of compacted clay liner
LANDFILL LINERS Construction of Dense Asphaltic Concrete Liner This is a new method of lining landfills. The first landfill to be constructed with this type of lining system in the UK is North of London and was completed this summer.
CONSTRUCTION QUALITY ASSURANCE All construction carried out on landfill sites is supervised and recorded by an independent consultant. Following construction, certification reports are produced by the consultant and issued to the Environment Agency for approval.
LANDFILL OPERATIONS Waste is placed in layers approximately 3 m thick and compacted. At the end of each working day approximately 0.3 m of clay or sand material is placed on top of the waste to: – minimise the infiltration of rainwater –isolate the waste from birds and vermin –reduce odours
LANDFILL OPERATIONS To prevent wastage and the formation of layers of weakness within the waste mass the daily cover is scraped off and re-used each day. Leachate that collects at the base of the waste mass is collected and re-circulated into the waste. This: –increases the rate of decomposition of the waste and therefore, rate of settlement; –decreases disposal costs.
LANDFILL CAP Landfill caps placed above the waste after completion of infilling prevent the infiltration of rainwater, minimising the production of leachate. Landfill Caps are usually constructed from: –Recompacted clay –Geomembrane
LEACHATE MANAGEMENT SYSTEM Leachate management systems are installed to: –prevent the accumulation of leachate in the base of the landfill –collect, re-circulate and dispose of leachate during operations and after closure They comprise of: –leachate drainage blanket at base of landfill –pipes along base and sidewalls of landfill –wells to monitor and extract the leachate
LANDFILL GAS MANAGEMENT SYSTEM Landfill gas management systems are installed to prevent the build up of gases within the landfill and to prevent migration of landfill gas through the underlying strata. There are 2 ways landfill gas can be managed: –passive –active
LANDFILL GAS MANAGEMENT SYSTEM Passive management systems comprise of wells with perforated tops to allow the gas to vent into the atmosphere Active management systems involve the active extraction of the gas. The extracted gas can be used to generate electricity.
MONITORING Monitoring is carried out before, during, and after the placement of waste. Numerous monitoring wells are constructed around a landfill site (both upstream and downstream) to check for contamination. Chemical testing is carried out regularly on: –Groundwater –Leachate –Landfill Gas
SUMMARY Landfill sites are not very pleasant! BUT The negative effects can be minimised if: – they are designed carefully with due consideration of the geological and hydrogeological conditions; –construction works are supervised & controlled by a qualified engineer; –they are carefully managed throughout their operational life and aftercare period.