A gas and liquid extraction system and method to efficiently capture the gas generated from the decomposition of organic matter, generally referred herein as the biomass, present in a landfill is disclosed herein. The system and method taking in account the presence of high amount of water and proposing landfilling methodology to allow the efficient capture of an as high as possible amount of gas from each and every ton of biomass contained in the landfill which is heterogeneous, anisotropic in nature and unsteady in term of fluid flow behavior.