What soil condition typically requires a greater separation from the trench bottom due to water saturation?

Clay soil is characterized by fine particles that are tightly packed together, leading to a low permeability rate. When the soil is saturated with water, it holds onto moisture rather than allowing it to drain away, which can result in standing water around or in the septic system.

This water saturation creates a risk of groundwater contamination and reduces the effectiveness of the septic system. The effluent from the septic system requires a specific distance from the trench bottom to ensure that it has adequate space to treat and disperse properly into the surrounding soil. Therefore, when working with clay soil, a greater separation from the trench bottom is necessary to account for these conditions and to maintain the health and functionality of the septic system.