Hardscape & GradingQuestion 52 of 100
A segmental retaining wall over a certain height typically requires what to prevent failure?
a.No drainage at all
b.Engineered design, proper drainage behind the wall, and often geogrid reinforcement
c.A smooth clay backfill packed tight
d.Only decorative facing
Explanation
Taller retaining walls carry large lateral soil loads and usually require engineered design, gravel backfill with a drain to relieve water pressure, and geogrid soil reinforcement. Without drainage, water pressure builds behind the wall and pushes it over. Many jurisdictions require permits and engineering above a set height, commonly 3 to 4 feet.
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