For geotechnical and environmental reasons, landfills are positioned above the regional water table and thus are formed in unsaturated conditions. This condition can be different if the drainage system and the rain regime of the site are such that they create a level of internal liquid in the landfill. During January and February 2019, excessive movements occurred in the slopes of the Brasília sanitary landfill. A geotechnical investigation indicated that the raised leachate level caused by the clogging of the drainage system contributed to the landfilled waste movements. The limit equilibrium analysis was used to predict the relationship between leachate level and slope stability. In order to understand the process that led to the rupture, flow and stability analysis by limit equilibrium were performed. The parameters associated with flow, water retention capacity, and shear strength were obtained based on literature evaluations. In addition, data from tests were used, which allowed to define more accurately the distribution of pore pressures of liquid that led to the failure. This study allowed to define the cause of failure and also to establish the role of the drainage system in maintaining the stability of the landfill. The studies indicated that although the gain of shear strength of landfill due to the unsaturated condition is negligible, the process of flow in unsaturated medium, associated with climatic aspects, are fundamental for a medium- and long-term analysis.

Leachate is a highly contaminating liquid generated in landfills, it is one of the main environmental challenges, especially with regard to its treatment, since its varied composition makes it difficult to choose a continuously efficient treatment. Without the proper treatment, it can cause contamination of the soil and surface and underground water resources. In this context, the present study carried out an analysis of the efficiency of the treatment of leachate generated in the landfill in the city of Maceió-AL, verifying its behavior over the years of operation, in addition to possible complications in its treatment. The information was obtained through on-site visits, as well as through secondary data provided by the Superintendency of Urban Cleaning of Maceió (SLUM). As for the treatment of leachate generated in the landfill in Maceió, there were many variations in the efficiencies obtained during the periods, which demonstrates the complexity in the treatment of leachate, especially in a landfill in operation, requiring the adoption of improvements over time. in order to get better results. The biological and coagulation, flocculation and decantation processes provided better performance in the treatment of leachate, obtaining an average global efficiency of 98.79%, 95.45% and 93.42% in removing biochemical oxygen demand (BOD), demand chemical oxygen (COD) and Ammoniacal Nitrogen, respectively.

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Among current methods, landfill is the most used - and least harmful according to the National Solid Waste Policy - for final disposal of Urban Solid Waste (MSW) with engineering techniques to control the waste components in the system. Leachate, resulting from the biodegradation of organic matter, is a highly contaminating liquid and an environmental challenge regarding its treatment. For the realization of the study, data were collected, for nine years, from the Landfill of Maceió assessing the behavior of the leachate parameters. The study consisted of evaluating the environmental parameters in their concentrations, the flow of the leachate generated and its correlation with precipitation. The values found showed that the landfill presents great variability in the concentrations of its parameters over time, mainly of Biochemical Demand and Oxygen (DBO) and Chemical Oxygen Demand (COD), which showed higher concentrations in rainy periods. The leachate flow increased in rainy periods, confirming the influence of precipitation. Ammoniacal Nitrogen, pH and Alkalinity did not show any influence of precipitation, being more related to the anaerobic degradation phase of the landfill, which currently tends to be in the methanogenic phase.

Construções sobre depósitos de solos moles são motivos de preocupação devido à alta compressibilidade e baixa resistência desses solos, sendo necessário conhecer suas propriedades geomecânicas e as técnicas de melhoramento. Na alternativa de reforço do solo, pode-se empregar geossintéticos na base do aterro, permitindo aumento da sua estabilidade, construção mais rápida e utilização de taludes mais íngremes. Este artigo apresenta o dimensionamento de geossintético para reforço de um aterro de solo mole localizado em Recife, Pernambuco, Brasil. O objetivo foi realizar a análise de estabilidade do aterro sem o reforço e com o reforço de geossintético, obtendo os respectivos valores dos fatores de segurança, e portanto, verificar a eficiência desse material para reforço da área estudada. Foram considerados os mecanismos de instabilidade de expulsão de solo mole de fundação e de ruptura generalizada envolvendo aterro, reforço e solo de fundação. Utilizou-se um programa computacional para realizar as análises de estabilidade. O fator de segurança contra expulsão do solo mole e o fator de segurança mínimo foram bem próximos, em torno de 1,3. O uso de geossintético como reforço para o caso estudado mostrou-se eficiente, com significante elevação do fator de segurança de 0,98 para 1,32. O fator de segurança para o uso combinado de geossintético de reforço e a construção de uma berma foi de 2,37, sendo o maior valor das três opções de estabilização do aterro. A solução adotada em projeto dependerá do valor do fator de segurança mínimo determinado pelo projetista. Diversos fatores como porte da obra, custo e prazo, assim como a logística da construção podem interferir na escolha da solução mais adequada. Esse artigo busca melhor entendimento do tema, e em consequência, projetar aterros mais seguros e econômicos.