Why is surface application often selected over other OSSF disposal options?

Surface application is often chosen as a disposal option for On-Site Sewage Facilities (OSSF) primarily due to specific soil conditions and groundwater levels that can impact other methods. In situations where clay soils are present, the ability of these soils to absorb and filter effluent can be limited, leading to potential system failures if traditional subsurface disposal systems are employed. The compact nature of clay can hinder water movement, causing effluent to pool and create problems.

Seasonal groundwater issues can also pose significant challenges for various disposal methods. High groundwater levels can saturate the disposal field, diminishing its efficacy and leading to effluent rise to the surface, which can cause contamination and health risks.

Using surface application in such scenarios allows for more consistent treatment of effluent, as it can be exposed to sunlight and air, enhancing the biological treatment process and reducing the likelihood of fly infestations or other nuisances. Thus, surface application can be an effective solution when dealing with the physical limitations imposed by clay soils and fluctuating groundwater levels.