Prismatic soil structure within 36 inches of the naturally occurring soil surface is considered what with respect to structure?

Study for the North Carolina Septic Inspector Exam. Use detailed flashcards and multiple choice questions with hints and explanations. Get exam-ready today!

Soil structure directly governs how well water and wastewater can infiltrate the ground. Prismatic structure means the soil forms vertical, pillar-like units, which often indicate tighter, more clayey subsoil with reduced pore space near the surface. When this prismatic arrangement is within 36 inches of the naturally occurring surface, the infiltration capacity of the absorption area is seriously limited. The result is poor drainage, higher risk of surface ponding or perched water, and insufficient treatment of effluent before it moves deeper. For septic systems, that combination makes the site unsuitable for an absorption field. If the prismatic feature were deeper or not affecting the uppermost profile, other classifications like provisionally suitable or suitable might apply, but in this case the near-surface prismatic structure leads to unsuitability.