Address Unsuitable Base Material (River Rock)

What happens here

The excavator removes any remaining unsuitable material, specifically noting the presence of river rock from the old base. The 'Dirt Monkey' reiterates that river rock is unsuitable for a retaining wall base because its rounded, smooth edges do not interlock effectively like angular rock, creating an unstable foundation that cannot adequately support the wall's weight.

Goal: Remove unsuitable river rock base and understand its structural deficiencies.