In terms of setbacks, what is measured from the perimeter of the basal area of the filter media?

The correct answer is that setbacks, as they relate to septic systems, are specifically concerned with the distance that must be maintained between the system's components—such as the filter media and any nearby features. This can include property lines, wells, bodies of water, and other structures. These setbacks are critical for preventing contamination and ensuring both system functionality and public health safety.

Setbacks measured from the perimeter of the basal area of the filter media help to establish the necessary buffer zones that protect the septic system from potential impacts from these other features. Adequate distance reduces the risk of pollutants entering water sources and ensures that the land surrounding the system is not adversely affected.

The other options pertain to different aspects of septic system design and implementation but do not specifically address the concept of setbacks in relation to the filter media. Soil depth requirements relate to the necessary amount of suitable soil above the filter media, ground slope percentages deal with drainage and water movement, while installation techniques focus on how the system is constructed rather than spatial relationships to other features. Thus, the focus on distance to other features in terms of setbacks is the principal reason for its correctness in this context.