La´zaro Valentin Zuquette Janaina Barrios Palma Osni Jose´ Pejon Environmental assessment of an uncontrolled sanitary landfill, Pocos de Caldas, Brazil Received: 8 May 2004 Accepted: 3 August 2004 Published online: 13 January 2005 Ó Springer-Verlag 2005 Abstract There are more than 20,000 uncontrolled sanitary landfill areas in Brazil. The paper reports an inte- grated study undertaken to develop an environmental assessment of the uncontrolled sanitary landfill area of the city of Poc¸os de Caldas, State of Minas Gerais, Brazil. A number of remedial alternatives were evaluated. The USGS modular 3D finite differ- ence groundwater flow model (Mod- flow) and Modular 3D Finite Difference Mass Transport Model (MT3D) software were used to sim- ulate groundwater flow and contam- inant transport modelling, as well as to predict changes due to the pro- posed remediation measures. The remedial alternatives considered for normal conditions from 20 to 40 year periods were waste removal, vertical cut-off barriers, extraction wells and top capping. The results indicated that extraction wells and waste re- moval are the best alternatives be- cause they significantly reduce both the extension and levels of the con- tamination plume even after 5 years. The extraction well proved a less expensive remedial alternative than waste removal. Keywords Uncontrolled sanitary landfills Æ Groundwater pollution Æ Numerical simulations Æ Remediation measures Æ Brazil Re´ sume´ Il y a plus de 20000 zones de de´charges non controˆle´es au Bre´sil. L’article pre´sente une e´tude inte´gre´e destine´e a` e´ valuer l’impact environnemental de ce type de de´- charge pour la ville de Poc¸os de Caldas, dans l’e´tat du Minas Ge- rais. Plusieurs solutions alternatives ont e`te´ e´tudie´es. Les logiciels 3D Modflow et MT3D de l’USGS ont e´te´ utilise´s pour simuler les e´coule- ments souterrains et le transport de polluants, ainsi que pour pre´voir les modifications re´sultant de mesures correctives. Les solutions alterna- tives conside´re´es pour des pe´riodes de 20 a` 40 ans e´taient l’enle`vement des de´chets, la re´alisation de bar- rie`res verticales de confinement, la foration de puits d’extraction et la couverture des de´poˆts. La re´alisa- tion de puits d’extraction et l’en- le`vement des de´chets sont apparus comme les solutions les plus ap- proprie´es car elles conduisent a` une re´duction significative de l’extension du panache de pollution et de l’in- tensite´ de pollution apre`s 5 ans. La re´alisation de puits d’extraction est moins couˆteuse que l’enle`vement des de´chets. Mots cle´s De´ charges non controˆ le´es Æ Pollution de nappe Æ Simulations nume´ riques Æ Mesures correctives Æ Bre´ sil Bull Eng Geol Environ (2005) 64: 257–271 DOI 10.1007/s10064-004-0268-z ORIGINAL PAPER L. V. Zuquette (&) Æ J. B. Palma O. J. Pejon Departamento de Geotecnia, Escola de Engenharia de Sa˜o Carlos, Av. Trabalhador Sa˜o-Carlense, 400 13, 566 - 590 Sa˜o Carlos, Brazil E-mail: lazarus1@sc.usp.br Fax: +55-16-2739509