Sensing, Analyzing, and Forecasting Evaluation (SAFE) System for Bioreactor Landfills

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ABSTRACT:During the past two decades, the majority of geotechnical and geoenvironmental research related to landfills using in-situ sensing systems and field methods has been focused on securing the boundaries of the landfills - caps and liners. This research concerns sensing the "heart" of landfills, which is the waste representing over 99% of the landfill. The proposed approach will use the data collected from sensors embedded in permeable blankets primarily used for routine leachate recirculation to continuously and in real-time model the changes in the hydraulic and thermal conductivities of waste. This is critical because hydraulic and thermal properties of the waste change as a result of settlement, decomposition, age, and other operational variables. Currently, we have only limited knowledge on the long-term behavior and risks associated with "megafills" operated as bioreactors. In addition, the proposed approach will be independently confirmed by doing controlled lab experiments using a lab-scale physical model of landfill followed by comprehensive numerical modeling and by conducting field tracer tests at an instrumented landfill site in Michigan.The research activities combine the use of well-established in-situ sensor technology to measure water content, liquid pressure, temperature, vertical stress, and settlement and sophisticated computer models in a unique manner to develop a knowledge base and preliminary framework for SAFE system capable of sensing, analyzing, and potentially forecasting landfill-specific behavior to optimize the performance of landfills and reduce environmental risks. Such sensor systems can be readily and consistently implemented at any landfill. This would herald the next era of landfill design, shifting the focus from boundaries to an overall landfill-specific approach.In parallel to the research activities, design of liquid injection systems for landfills will be interwoven with undergraduate research and course development. An easy to use labscale physical model of landfill will be designed and built to make it possible for students to observe, investigate, control, and interact with the hydraulics of liquid collection and injection systems in ways not previously possible. The relatively compact landfill demonstration model will provide an innovative educational tool for teaching landfill design or equivalent courses at Michigan State and other universities. This project will allow collaboration with landfill regulators and operators and will allow undergraduate students to participate in an existing NSF-funded international project, providing a unique research opportunity. It would also provide new learning directions for minorities and female students via local high school programs serving these groups that are actively tied to Michigan State University. The economic impacts of the proposed research will accrue with our ability to potentially reduce long-term risks and financial liabilities associated with over 2,000 ubiquitous active landfills in the U.S. and as recycled materials find an additional market.