The soil selection for a site is a major deciding factor for assessing the characteristics of a site and plays a vital role in the process of Site Selection. The soil in a particular area has its own characteristics which it attains, with its exposure to environmental exposures, over the years.

Thus, it is of utmost significance that the site selected must be furnished with soil, which supports all sorts of constructions.

The SUBSOIL CONDITIONS are checked by simple experiments.

Ploughing of the site will reveal the nature of material in the upper crust of the earth. Presence of organic fill and animal wastes such as bones, hair, cinder, etc., indicate a site unsuitable for building purposes. The presence of vermins and termites of foul smell may also serve as indices of bad condition.

VASTUVIDHYA even suggests testing of soil for the site selection.

Presence of hollows in the ground made by termites or rodents may be easily detected by tamping the ground by foot and listening to the sound. Vastuvidya recommends keen observation, putting all the perceptual senses (jyanendriyas- seeing, hearing, touching, smelling and tasting) in use to assess the site characteristics.

A simple and effective way is suggested in the texts for ascertaining the compactness of the subsoil for building purpose.

Here, a pit of 1H square and 1H depth is excavated. It is then filled again by the excavated soil. If the soil readily fills the pit, the site is not considered compact enough for building purposes. If a good portion of the excavated soil remains even after the pit is filled, it is an indication that the original soil was compact and consolidated and hence, suitable for building purposes.

The imperviousness of the substrata could be tested by filling the pit with water and watching the fall in the water level.