Any soil profile with an indication of high-water table within _____ inches below the proposed drainfield shall be considered _____________ for a standard drainfield.

The correct response indicates that any soil profile showing a high-water table within 24 inches below the proposed drainfield is deemed unsuitable for a standard drainfield. This is essential for ensuring the effectiveness and safety of wastewater treatment systems. A high-water table can lead to saturated soil conditions that impede proper drainage and the functioning of the drainfield, potentially causing surface water contamination and groundwater pollution.

A high-water table within this proximity can create an environment where the effluent from the drainfield cannot adequately percolate or be treated by the soil, leading to system failure, odor concerns, or public health risks. Thus, maintaining a minimum vertical separation distance of 24 inches is critical to promote adequate soil absorption, treat sewage effectively, and protect the environment.