The site layout incorporates the site and waste characteristics into an operating strategy. Materials handling is concerned primarily with the solid phase, most often soil, at a hazardous waste site. A hazardous waste site clean-up operation involves many intricate tasks prior to, during, and after treatment of the contaminants present. Excavation of contaminated materials places workers at potential health and safety risks. Scheduling during optimum time period in terms of climate may provide the lowest cost solution to the problems of airborne or liquid phase contamination. The reason for site access control, outside of safety concerns, is to minimize the spread of contamination. The bulk of decontamination efforts will be performed in conjunction with materials handling or processing equipment. Stock piling of contaminated soil is often necessary to allow a continuous operation of expensive treatment systems. The reason for site access control, outside of safety concerns, is to minimize the spread of contamination.