How invasive iguanas damage SWFL seawalls, and how foam stabilization restores them
If you live on a canal or coastal lot in Southwest Florida, you already know iguanas. What’s less obvious is how much damage they do to the structure that’s keeping your yard from sliding into the water.
What iguanas do to seawalls
Green iguanas are prolific burrowers. They dig into the soft fill behind seawalls, usually right at the cap line where it’s easiest to start a tunnel, and excavate networks of voids that can run several feet deep. A single mature iguana can move a surprising amount of dirt in a season.
That burrowing creates three structural problems:
- Direct void formation. The tunnel itself is empty space behind the wall, with no soil pressure where the wall expects it.
- Erosion acceleration. Tide and rainwater find the burrows and use them as channels, pulling more fill out and enlarging the voids.
- Cap undercutting. Burrows that follow the line of the cap undermine the support directly beneath it, leading to cracking or eventual cap failure.
By the time the homeowner notices a depression on the lawn or a hairline crack in the cap, the cavity behind the wall is usually much bigger than it appears.
Why patching with concrete doesn’t work
The first instinct is to fill the hole with something heavy: concrete, sand-cement slurry, anything to make the empty space go away. The problem is that you’re adding weight to soil that’s already failing, on top of a wall that’s already stressed. The patch eventually sinks, the wall feels more lateral pressure, and in the worst cases the whole repair becomes part of the next failure.
What polyurethane injection does
Our process targets the actual problem: the soil column itself.
We inject a certified, eco-friendly polyurethane resin through small ports either through the cap or directly into the soil mass. The resin expands, permeates the surrounding fill, and binds it into a stabilized, water-resistant mass. It’s lightweight, so it doesn’t reload the wall. It’s structural, so it carries load without compressing. And it’s chemically inert once cured, so it poses no risk to the bay or the marine environment.
In practical terms:
- The voids the iguanas dug are filled.
- The surrounding loose soil is bound and stabilized.
- The erosion channels are sealed off.
- The wall stops experiencing the lateral pressure swings that were driving its movement.
What you can do now
- Walk the lawn behind your seawall after a heavy rain or king tide. Look for new depressions, soft spots, or areas where the ground feels hollow.
- Check the cap for new cracks or shifts in alignment.
- Look for visible burrows along the cap line or near drainage fixtures.
- If you see any of these, get an assessment sooner rather than later. The fix is dramatically cheaper before the wall starts to lean.