Embodiments of the invention provide systems and methods for creating, managing and staging aerobic and/or anaerobic landfills. Embodiments of the invention provide systems and methods for collecting liquids from and recirculating liquids into landfills and systems and methods for collecting gases from and introducing gases into landfills. Embodiments of the invention also provide a novel conduit for conveying liquids and gases which comprises a first pipe coaxially disposed within a second pipe.