How much larger does the bottom of a seepage bed need to be compared to what is determined by the soil chart?

The bottom of a seepage bed needs to be 1.5 times larger than what is determined by the soil chart to ensure effective waste management and drainage. This increase in size accounts for variations in soil permeability, compaction, and the overall absorption capacity of the soil in the area. By enlarging the seepage bed, it allows for a greater volume of effluent to be absorbed, reduces the risk of saturation in the surrounding soil, and helps prevent backup or contamination of groundwater sources.

This step is critical in septic system design as it aims to maintain a safe distance from groundwater and surface water, adhering to environmental regulations and protecting public health. The decision to use a 1.5 times multiplier reflects a standard practice based on empirical data and research within the field, ensuring that septic systems function effectively under varying environmental conditions.