Why is it important to avoid heavy machinery over a drain field?

Avoiding heavy machinery over a drain field is crucial primarily to prevent soil compaction and potential damage to the septic system. Heavy machinery can compress the soil, reducing its porosity and permeability. This compaction restricts the movement of wastewater through the soil, limiting its ability to filter and treat effluent effectively. As a result, the drain field could fail, leading to system backups or surface water contamination, which poses environmental and health risks.

The other options relate to soil health and functionality, but they do not directly address the immediate risks posed by the use of heavy machinery on a drain field. While improving soil fertility, water absorption, and air circulation are beneficial for soil health, these objectives can be negatively impacted when soil is compacted due to heavy machinery operating over the drain field. Therefore, maintaining the integrity of the soil structure above a drain field is essential for the proper functioning of a septic system.