Inspect Drainage Backfill Material

What happens here

The most glaring error highlighted by the presenter is the type of material used for the drainage backfill. He emphatically states that instead of the industry-standard 3/4 inch limestone or crushed gravel, "pea gravel" (small, rounded stones) was used. The presenter picks up a handful of this pea gravel to clearly show its characteristics to the camera. Pea gravel is fundamentally unsuitable for drainage backfill in retaining walls because its rounded shape provides poor interlocking characteristics, leading to inherent instability and inadequate compaction. Furthermore, its smooth surface allows water to move too quickly without proper filtration, and it lacks the angularity needed for effective structural support against lateral soil pressure, contributing significantly to the wall's premature collapse.

Goal: Identify the use of inappropriate pea gravel as drainage backfill.