This practice should be used as the initial step for evaluating a site for its potential to support an on-site septic system and to determine the best location for subsurface observations as covered in Practice D5921.

This practice should be used by individuals involved with the evaluation of properties for the use of on-site septic systems. Such individuals may be required to be licensed, certified, or meet minimum educational requirements by the local or state regulatory authority. Generally, such individuals should be familiar with the appropriate regulatory requirements governing the design and placement of on-site septic systems for the area of the site being investigated, and at least some experience or training in geomorphology, soils, geology, and hydrology.

This practice is one step in the design of an on-site septic system that also includes subsurface characterization, see Practice D5921, staking and protection of the soil absorption or constructed filter bed area, see Practice D5925, selection of system type, and design of the system size and configuration. Typically, the same individual will perform the surface and subsurface characterization of a site. Local regulation and practice will determine whether the same individual is responsible for all steps in the process of locating and designing an on-site septic system. Effective surface and subsurface characterization of a site for on-site septic systems, however, requires some knowledge of the following for the county or state in which the site is located: (1) on-site septic system types typically used for different soil conditions, and (2) typical soil absorption/filter bed areas required for different wastewater flow rates and areal soil wastewater loading rates.