The depth of soil classified as suitable with respect to texture shall be at least ____ inches below the bottom of the proposed excavation for a standard drainfield.

The correct answer is that the depth of soil classified as suitable with respect to texture shall be at least 24 inches below the bottom of the proposed excavation for a standard drainfield. This requirement helps ensure that there is adequate soil material to treat wastewater effectively before it reaches groundwater or other sensitive areas.

Soils that meet this depth criterion tend to provide sufficient filtration and absorption capabilities, which are essential for minimizing the risk of contamination and ensuring the proper function of the drainfield. A depth of 24 inches is typically considered a standard that balances the soil's ability to filter pollutants while providing enough buffer between the wastewater and underlying regions that may be susceptible to saturation or contamination.

This regulation is part of best management practices in site selection for wastewater treatment systems, ensuring that the environment is protected and that the systems can operate efficiently. Other options may not provide the necessary buffering or treatment range needed for effective wastewater management.