CARUARU MUNICIPAL SOLID WASTE LANDFILL: A CASE STUDY ON GASES RETENTION IN THE COVER LAYER

Abstract

The landfills cover layers are responsible for isolating waste, reducing the infiltration of rainwater into the massif, and preventing the gases generated in the organic matter biodegradation process from reaching the atmosphere. This article presents the evaluation of gases retention in the cover layer of the Caruaru Municipal solid waste landfill, located in the northeast Brazil. The landfill activities were closed in March 2018. The cover layers were evaluation by geotechnical characterization of the soil (classification, granulometry, degree of compaction, moisture, degree of saturation, void index, and layer thickness). In the field, 20 static flow plate tests were performed to verify the amount the gas that reached the surface through the cover layer. The tests were carried out in 4 stages, at 5 different points selected according to the age of the waste deposited there (2, 4, 6, 8 and 10 years, respectively). Due to the low emissions indicated by plate tests, the generation of gases within the tailings mass was investigated through 20 pressure and concentration tests with the aid of the Pressure and Concentration Measuring Device (DMPC) and the emissions of gases were analyzed in 9 drains that were close to the points of the other field tests. According to the granulometric analysis of the material, 4 of the samples collected on the ground consisted of sandy materials (silty sand, clayey sand and well-graded sand) and 1 sample had sandy clay. The results of the void indexes were between 0.5 and 0.63, the degrees of saturation were between 64.4% and 90.6%, the moisture contents were between 17% and 20.3% and the degrees of compaction between 80% and 90%...