THE LEACHATE COMPOSITION OF AN OLD WASTE DUMP CONNECTED TO GROUNDWATER - INFLUENCE OF THE RECLAMATION WORKS

This study has been carried out in an uncontrolled dump in the suburbs of Buenos Aires, Argentina. This dump still contains solid wastes of different types in direct contact with the human consumption aquifer. After 18 years of overturning the dump was closed in 1992, and the rec lamation works started. Three leachate samplings were carried out in t hree different zones of the dump, selected according to the topography , the age of residues and the degree of water contact. These samplings were done before the reclamation works, at the end, and four months a fter they were finished. Several chemical parameters, including heavy metals in solid and dissolved fractions, were analyzed. Multivariate a nalysis (PCA) was performed to help to understand the effects of the l abors on leachate composition. The works could be responsible for a te mporal increase of dissolved heavy metals and several chemical variabl es in the leachate. At the sites of the dump where the modifications w ere carried out, the levels of some elements analyzed recovered their former values a few months after the reclamations works. At the farthe st site, the impact and recovery effects of the works on leachate comp osition, were delayed.