Which factor is crucial when assessing soil type for an OSSF?

When assessing soil type for an On-Site Sewage Facility (OSSF), the drainage capability and permeability of the soil are essential factors. This is because these characteristics directly influence how well the soil can absorb and filter wastewater. Proper drainage ensures that effluent does not pool on the surface or back up within the system, which can lead to system failure and environmental contamination.

Permeability refers to how easily water can move through the soil, impacting the effectiveness of the soil in treating wastewater. Soils with high permeability may allow wastewater to pass through too quickly, while those with low permeability may not let it flow adequately, resulting in potential saturation.

Other factors, while important, do not have the same level of direct impact on the functioning of an OSSF. For example, soil moisture retention is relevant but primarily affects how the soil interacts with water rather than its capability to handle septic drain fields effectively. The type of vegetation can provide some insight into the drainage and overall health of the soil but does not quantify its capacity to manage wastewater. Similarly, soil color and appearance can indicate certain characteristics of the soil, such as organic matter or moisture level, but do not provide concrete information about its drainage or permeability. Thus, focusing on drainage capability and permeability is