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Construction |
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University of Padua IMAGE Department |
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Drainage Leachate drained from the bottom of the landfill, has to be collected continuously in order to avoid leachate hydraulic head over the barrier system. Collection manholes must have the following characteristics: • Installation outside the waste deposit area • Dimensions allowing satisfactory maintenance and working activity • Materials should be impermeable and resistent to leachate corrosion (often pre-manufactured polyethylene and fibreglass wells are installed) • Leachate pipe must be syphoned on arrival in manholes and water guards should invariably be present in order to avoid air infiltration in the leachate drainage and consequent clogging problems Drainage solution |
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Types of damage • Deformation due to the imposed load and high temperatures (synthetic pipes) • Arching of the base of the pipes and in the case of plastic tunnel pipes • Longitudinal and radial cracks (earthenware pipes), including distortion • Fracturing, breakage and displacement of the pipes • Silting-up with fine material • Growth of bacterial sludge • Recrystallization Causes of damage • Incorrect assumptions for static computations • Construction deficiencies, such as local settlement, absence of or incorrect pipe bedding, inadequate pipe covering, unsuitable pipe materials, unsuitable gravel types • Operating faults, such as driving vehicles over pipes with too little cover, displacement of pipes during landfilling activities, etc. Pipe systems must not only ensure the collection and rapid removal of leachate, but it must also be possible to inspect, maintain and repair them. |
