What type of layer in soil can support root growth in a sewage system?

A permeable layer in soil is fundamental for supporting root growth in a sewage system for several reasons. This layer allows for the adequate movement of air, water, and nutrients, all of which are critical for plant health. When the soil is permeable, it facilitates the infiltration and drainage of water, preventing saturation that can lead to root rot and other issues related to excess moisture. Additionally, the presence of a permeable layer enhances the biological activity in the soil, enabling beneficial microorganisms to thrive, which can help with the breakdown of organic matter and improve soil fertility.

In contrast, a restrictive layer would inhibit root penetration and limi the movement of water and air, thereby affecting plant growth negatively. A compact layer, being dense, would also restrict roots and drainage, making it difficult for plants to establish themselves properly. A saturated layer is typically oversaturated with water, creating anaerobic conditions that are detrimental to root systems since roots require oxygen for respiration and growth. Thus, a permeable layer is essential for a healthy sewage system and promotes robust root growth.