Information on the overall range and diversity of contamination across the site is critical to treatment technology selection. Obtaining this information generally requires taking samples and determining their physical and chemical characteristics. If certain types of technologies are candidates for use, the specific data needs for these technologies can be met during the initial stages of the investigation. The following subsections present a partial list of the characteristics and rationale for collection of treatment technology preselection data for each of the three media. Process-limiting characteristics such as pH or moisture content may sometimes be adjusted.
Soils are inherently variable in their physical and chemical characteristics.
Usually the variability is much greater vertically than horizontally, resulting from the variability in the processes that originally formed the soils. The soil variability, in turn, will result in variability in the distribution of water and contaminants and in the ease with which they can be transported within, and removed from, the soil at a particular site. Many data elements are relatively easy to obtain, and in some cases more than one test method exists. Field procedures are performed for recording data or for collecting samples to determine the classification, moisture content, and permeability of soils across a site. Field reports describing soil variability may lessen the need for large numbers of samples and measurements to describe site characteristics.