Geotechnical Stability of Waste Fills: Lessons Learned and Continuing Challenges

Several noteworthy stability failures occurred at landfills in the United States in the 1980s and early 1990s, a timeframe coinciding with the promulgation of modern US environmental regulations. These failures were extensively studied, and lessons were learned. A state-of-practice developed to enable the design of waste fills to be stable throughout their construction, operation, and closure periods. However, a survey of landfill performance in the United States in the 2010-2019 timeframe shows that waste fill stability failures continue to occur. This paper, an expansion of the 2018 Terzaghi Lecture given by the first author, presents a brief review of several waste fill failures from the 1980s and 1990s and the lessons learned during that period. Several more recent waste fill failures are then reviewed, from which it is concluded that 20-30 years after the earlier failures, facility operators and design engineers are relearning the earlier lessons, as well as new lessons related to evolving waste streams and operating practices. The paper concludes with a discussion of the current standard-of-care for the design of US waste fills and suggests that this standard can be improved through application of the lessons described herein. (c) 2020 American Society of Civil Engineers.