The "hazard" associated with a waste essentially controls the overall engineering approach to finding suitable alternatives for solving potential disposal problems. It should be recognized that all factors affecting environmental equilibrium must be considered, including product sales, process design, financing, pre- and end-of-pipe treatment, residuals management, and ultimate bioaccumulation of residuals. To meet this challenge, a systems approach to waste treatment and residuals disposal provides a logical approach, but this management concept requires a thorough understanding of the important physical and chemical aspects of the problem, as well as many social implications of the resulting decisions. Thus waste management within a plant necessarily involves process control, pretreatment and end-of-pipe treatment. Further, it follows that residuals management from a disposal point-of-view must ultimately embrace what is called the "multi-barrier concept." In essence, hazard elimination occurs in varying degrees during each phase of a properly engineered system.