Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Chapter 5: Modernising municipal wasteKnowledge of this process challenges <strong>the</strong> idea that landfills can really be isolated from<strong>the</strong> environment. The waste body produces water from chemical processes and is alsoinfiltrated by rainwater. The water picks up various contaminants to turn into <strong>the</strong>‘landfill soup’ known as leachate. It is supposed to be treated and <strong>the</strong>n disposed to <strong>the</strong>municipal sewage works. In South Africa, most leachate is not treated.Gases – some smelling foul and o<strong>the</strong>rs odourless but dangerous – must also escape <strong>the</strong>waste body. Landfill gas was until recently simply seen as a threat, mainly because <strong>the</strong>methane is explosive. In 1986, a gas explosion at <strong>the</strong> Loscoe dump in <strong>the</strong> UK – in anold clay quarry that had been filled and <strong>the</strong>n capped – blasted a house 70 meters awayand injured <strong>the</strong> three occupants. Damage to local vegetation indicated high landfillgas concentrations and potential danger before <strong>the</strong> blast. Landfill gas managementsolutions are passive venting (which really means just letting <strong>the</strong> gases escape) or a gasremoval system feeding gas ei<strong>the</strong>r to a flare or for use as energy.Materials used to contain <strong>the</strong> waste body – clay caps on top and liners at <strong>the</strong> bottom –are subject to stresses from <strong>the</strong> movement of <strong>the</strong> waste body as waste decomposes andcompacts. Liners may also tear, be eaten by acidic or caustic agents, or be punctured bysharp objects or burrowing animals. The liners are designed to last 50 years. In SouthAfrica, new landfills are planned for 20 to 30 years’ operation with a 30 year aftercareperiod. At <strong>the</strong> end of this period, <strong>the</strong> liner is expected to fail. This does not mean,however, that <strong>the</strong> waste body will no longer be polluting.Box 20: What’s in landfill gasLandfill gas (LFG) is between 40 and 60% methane, with most of <strong>the</strong> rest beingcarbon dioxide. It contains varying amounts of nitrogen, oxygen, water vapour,sulphur and hundreds of o<strong>the</strong>r contaminants, mostly (non-methane) volatileorganic compounds (VOCs) but sometimes also metals such as mercury.VOCs usually make up less than 1% of landfill gas. The US EPA has identified 94in LFG although o<strong>the</strong>r tests have found many more. They include benzene, toluene,chloroform, vinyl chloride, carbon tetrachloride, and trichloroethane. At least 41on <strong>the</strong> EPA’s list are halogenated compounds – containing chlorides, fluorides andbromides – which give rise to dioxins and furans when LFG is burnt ei<strong>the</strong>r in flaresor for energy.Source: Mike Ewall, Energy Justice Network.- 132 - groundWork - <strong>Wasting</strong> <strong>the</strong> <strong>Nation</strong>