Seawalls · 5 min read
What Causes Soil Erosion Behind a Seawall?
Soil loss behind a seawall is one of the most common waterfront problems in South Florida — and one of the most misunderstood. The yard doesn't sink on its own. Something is pulling it out.
How It Happens
Water moves through any opening in the wall. On a falling tide, water behind the wall drains out toward the waterway and carries fine soil with it. Repeat that twice a day for years and you get voids — and eventually sinkholes.
Common Causes
Open or failed joints
Gaps between panels are the number one path.
Cracks in the wall
Especially below the waterline where you can't see them.
Failed filter fabric
Fabric behind joints deteriorates over time.
Heavy rain
Saturated soil pushes water — and soil — toward the wall.
Scour at the toe
Loss of material at the base can open paths under the wall.
Why Filling the Sinkhole Doesn't Fix It
Topsoil in a sinkhole covers the symptom. The leak is still there. Real seawall erosion repair seals the path and fills the voids behind the wall.