What is meant by the term "saturated soils" in the context of OSSF?

The term "saturated soils" in the context of On-Site Sewage Facilities (OSSF) refers to soils that are fully filled with water, which significantly limits their ability to absorb effluent. When soils become saturated, all the pore spaces are occupied by water, leaving no room for air or for any additional liquid, such as wastewater. This condition severely restricts the soil's natural filtration and treatment processes that are essential for effective sewage management.

In a saturated state, the soil's capacity to treat effluent is compromised, as adequate air and microbial activity are crucial for breaking down contaminants. As a result, effluent may accumulate on the surface or move laterally rather than percolating into the ground, leading to potential environmental issues and system failures.

Understanding the behavior of saturated soils is critical for designers and installers of sanitary systems, ensuring that septic systems are placed in locations where soil saturation will not impede their functionality. Hence, the characterization of soils in terms of their saturation is a key consideration in the planning and implementation of OSSF.