What material is placed above the distribution pipes?

What material is placed above the distribution pipes?

• A. Septic stone
• B. Gravel
• C. Sand
• D. Topsoil

Answer: (A)

The key idea is that the area directly above the distribution pipes needs a clean, free-draining layer to spread the effluent and keep soil from clogging the pipes. Septic stone is a washed, coarse aggregate designed for this role, providing the voids that let liquid move evenly into the surrounding trench. Sand would clog the pores and impede drainage, topsoil would compact and block infiltration, and while gravel can serve a similar purpose, septic stone is the material specified for this layer in many on-site systems. So, the material placed above the distribution pipes is septic stone.

The key idea is that the area directly above the distribution pipes needs a clean, free-draining layer to spread the effluent and keep soil from clogging the pipes. Septic stone is a washed, coarse aggregate designed for this role, providing the voids that let liquid move evenly into the surrounding trench. Sand would clog the pores and impede drainage, topsoil would compact and block infiltration, and while gravel can serve a similar purpose, septic stone is the material specified for this layer in many on-site systems. So, the material placed above the distribution pipes is septic stone.