ABSTRACT. Chaotic urban expansion often leads to hazardous environmental consequences. The absense of rainwater outflow management, coupled with low cohesion in some terrains is a geotechnical threat for the population since it may lead to gully formation...Keywords: piping, geophysics, electrical resistivity, electrical resistivity tomography. RESUMO. A expansão urbana desordenada pode gerar graves consequências ao ambiente. A falta de planejamento no escoamento de águas pluviais, aliado à baixa coesão de alguns terrenos pode proporcionar o surgimento de voçorocas,Palavras-chave: piping, geofísica, resistividade elétrica, tomografia elétrica.

ABSTRACT. The management of contaminated sites includes the purchase of a data set ranging from the historical information of the occurrence, preliminary and detail diagnostic, monitoring and remediation...Keywords: contamination, leather, resistivity, chargeability, 3D modeling. RESUMO. O gerenciamento das áreas contaminadas prevê o levantamento de um conjunto de dados que variam desde informações do histórico da ocorrência, diagnóstico preliminar e de detalhe, remediação e monitoramento...Palavras-chave: contaminação, couro, resistividade, cargabilidade, modelamento 3D.

Biogas is a chemical compound rich in methane, generated by the degradation of organic matter, flammable power and applicable to energy generation. Landfills are areas with great potential for biogas generation due to the large amount of organic matter contained in solid domestic waste. The sizing and design of projects to capture and generate energy in landfills depend on reliable estimates of future generation of biogas. The currently available models are deficient in many respects due to the exclusion of relevant factors in the biogas generation process. This paper presents the results of natural electric potential through geophysical logging technique, developed alongside gas drains located in areas with residues of different ages of landfill deposition, when accompanied by measures of biogas flow and rainfall, biweekly during 12 months. The key objective was to evaluate the sensitivity of the physical parameter to seasonal variations and its relation to the production of biogas. The results show that the availability of organic matter able to degradation was the main factor responsible for differences in biogas production between the drains examined, although there are variations in periods of drought or rain. The natural electric potential demonstrated proportional variations of biogas flow rates measured in drains with different ages, where the largest biogas flows are associated to more electronegative or more reducing areas

ABSTRACT. This work relates measures of the biogas flow in drains located on landfill with measurements of electric resistivity, obtained by the technique of geophysical logging by measuring cable installed in two vertical boreholes near to two biogas drains, with different flows. The results indicate that variation in rainfall, generation and accumulation of biogas in landfill, are repairable correlation with oscillations in electrical resistivity measures. The biogas production is apparently conditioned by age of residues and organic matter available from the degradation. The biogas drain in region with low production of biogas does not present resistivity pattern directly or indirectly correlated to biogas production, while the biogas drain in region with high gas production was characterized by high resistivity values, with seasonal variation by influence of rainfall.