The design of a raised filter bed mantle should not exceed what percolation rate?

A percolation rate of 120 minutes per inch is significant in the design of a raised filter bed mantle because it directly impacts the efficiency of wastewater treatment. In this context, a slower percolation rate indicates a more impermeable soil, which may not effectively absorb and treat effluent. If the rate exceeds this threshold, it may lead to poor drainage and increased risks of system failure or environmental contamination.

By adhering to the 120 minutes per inch guideline, designers can ensure that the septic system has adequate time to process the wastewater while preventing saturation of the soil. This balance is essential for maintaining proper soil function and minimizing risks such as surface drainage problems or septic system backups. Additionally, controlling water infiltration rates helps protect groundwater quality, which is vital for public health and environmental sustainability.