In what scenario might a mound system be considered for OSSF?

A mound system is specifically designed to address situations where the existing soil conditions are inadequate for effective wastewater treatment due to their depth or texture. The purpose of a mound system is to create an alternative treatment area above the natural soil level, ensuring proper filtration and treatment of effluent before it enters the groundwater.

When the existing soil is insufficient—either too shallow to adequately treat wastewater or composed of materials like clay that do not allow for proper drainage—installing a mound system provides a solution. The raised structure allows for the dispersal of wastewater to occur in a controlled manner, promoting aeration and biological treatment. By layering gravel and sand, the system enhances absorption and filtration, which helps to protect both public health and the environment.

In contrast, situations involving sandy soils, high water tables, or proximity to water sources typically present different considerations. Sandy soils often have good drainage properties, which could lead to rapid percolation, possibly making a traditional system more appropriate. High water tables pose a risk of effluent surfacing, while nearby water sources could raise the need for more stringent separation requirements, suggesting other types of systems may be more effective. Thus, the mound system is most relevant when existing soil conditions fail to provide the necessary treatment capabilities.