2 BackgroundKabwe is the second largest city in Zambia with a population of 300,000.In 1902 lead was discovered in the mineOre veins with lead concentrations up to 20% have been mined deep into the earth.The mine closed in 1994The government failed to address the potential danger of leadThe city has been left with hazardous concentrations of lead in the soil and water.
3 Problem Wide spread soil contamination Highly contaminated mine waste dumps simply left once the mine closed
4 Smelters emitted dust particles that settled over a 20 km circumference and became buried in the soil.The local canal became contaminated with lead which lead further ground contamination during flood events
6 Ground Effects High concentrations of lead found in soils levels of lead right next to the smelter measured 245,000 parts per million (ppm)Levels in a local township ranged from 7,000 ppm to 38,000 ppmLead content of soil in residential areas should not be more than 400 parts per millionIndustrial and agricultural sites
8 Human Effects Lead is one of the potent neurotoxins in the world In total 200,000 people were affected by the contaminationSome children were found to have more than 200µg/dlSymptoms of acute poisoning occur at levels above 20µg/dlLevels above 70µg/dl are considered a medical emergency
9 Solution Implemented Removal of 39,000 m3 of mine waste Removal of m3 of dredged sedimentsContaminated soil removed to a depth of 30cm.Liming of soilPlanting a vegetation coverDemolition of defunct plant infrastructure
10 Alternative Solutions VitrificationCappingSoil washingRelocate neighbourhoodsImprove public awareness and education programme