Studies which have been undertaken to improve burial techniques to prevent the intrusion of buried wastes by plants and animals are described. The study consists of two parts. The first part is a demonstration trench in which a layer of cobble has been placed over simulated wastes and covered with a deep layer of topsoil. The second part is an experiment in which several different kinds of biological barriers are tested in a replicated plot design. The ''simulated wastes'' consist of soil mixed with lithium chloride, which is biologically available and can be easily detected by spectrophotometric analysis. The purpose of the study is to evaluate the effectiveness of these barriers to biological invasion of buried wastes.