Why is the ground behind my seawall sinking?
The soil behind the wall is washing out through an opening. Each tide or rain pulls a little more fill into the water until a hollow forms and the surface drops.
A seawall has to let water out from behind it while holding the soil in place. Coastal drainage guidance When that balance fails, soil leaves with the water. Common paths include:
- Open panel joints: gaps between slabs or sheets.
- Weep holes without filter fabric: drain openings with no cloth to hold soil back.
- Torn or missing filter fabric: the cloth behind the wall has failed.
- Under the toe: the base is scoured and soil escapes beneath the wall.
- Cracks in the face: openings that grow with each surge.
Stay safe around a hole behind the wall
A small dip at the surface can hide a large hollow below. Treat it as unsafe until someone checks it.
- Keep people, pets, vehicles and equipment off the area.
- Mark it with stakes or tape, and do not probe it yourself.
- Hold off on filling it, because fill hides the evidence of the leak path.
- Photograph the hole at low and high water, with the date and a reference point.
If the wall itself starts to move, stay back and call a professional right away.
How to trace where the soil is going
| Clue | What it suggests | How a professional checks |
|---|---|---|
Muddy water at one joint as the tide falls | That joint is the main path | Dye test or camera at the joint |
A fan of sand on the bottom at the base | Soil escaping under the toe | Underwater look at the toe |
A hole right behind a weep hole | Missing or failed filter fabric | Open up behind the weep hole |
Holes along a long stretch | Widespread fabric failure | Test pits at several points |
Holes only after storms | Surge water draining back through the wall | Compare storm and dry-weather photos |
These are questions, not a diagnosis. The assessment guide explains how to scope the investigation.
When soil loss becomes a code problem
Soil pouring into a canal can draw enforcement. In January 2026, Mexico Beach’s Building Department sent a stern letter to the owner of a Water Street seawall. The city said the wall had failed or was not installed correctly, and soil was leaking into the canal. Mexico Beach weekly report, Jan. 2026
Bay County’s code says no new development may add to shoreline erosion of any property. It also requires silt fence or similar controls for work next to the shoreline. Bay County LDR 1904(2)
Soil loss does not respect property lines. A hollow at a shared lot line can undermine the neighbor’s wall too. Talk early, and see the neighbor project guide.
Rain and surge on this coast speed up soil loss
Two forces push water through these walls: heavy rain behind them and surge in front. Hurricane Sally in 2020 brought over 14 inches of rain to Bay County, and Tropical Storm Fred dropped nearly 9 inches at Southport in 2021. Bay County 2025 LMS NHC Fred report
During Isaias, surge and heavy surf overwashed coastal roads and damaged seawalls from Walton County to Franklin County. NWS Tallahassee Isaias report Water that tops a wall has to drain back out, and it carries loose soil through any gap.
Daily tides are gentle by comparison. Panama City usually sees one high and one low tide a day, so one low-water check each day shows the most of the wall. NOAA Panama City station
Soil loss fixes compared
| Fix | When it fits | Watch out for |
|---|---|---|
Refill the hole only | Never as the whole fix | The hole returns while the path stays open |
Joint repair plus new filter fabric | One or a few known leak points | Needs digging behind the wall |
Voids behind a sound wall, after the path is found | Can block drainage if every gap is sealed | |
New weep holes with fabric | Water pressure building behind a tight wall | Must be paired with filter cloth |
Toe repair or riprap at the base | Soil escaping under a scoured toe | Work in the water brings more permits |
Failure along most of the wall | Largest cost and permit scope |
Ask for a fix that closes the path and keeps drainage working. Then the backfill should go back in thin, compacted layers.
Permits for backfill and drainage work
How much fill you add can affect state exemptions. Florida’s permit handbook separates restoring a failing wall from expanding or reclaiming upland, and the reason for the work matters. ERP handbook
- Unincorporated Bay County: Planning and Zoning issues fill placement and grading permits and can be reached at (850) 248-8250. Bay County Planning and Zoning
- Panama City Beach flood zones: floodplain site plans must show the amount, type and source of fill, with evidence it is the minimum needed. Panama City Beach LDC 3.02.05
- Repairs to the wall itself: in unincorporated Bay County, structural seawall repair needs a building permit. Bay County permit requirements
Check the full route on the permit guide, and price the job with the cost guide.
Questions to ask before you sign for soil loss repair
- Where exactly is the soil escaping, and how did you confirm it?
- How will water keep draining from behind the wall after the fix?
- What fill will you use, and how will you compact it?
- Will you restore pavers, sod and irrigation you disturb?
- Does the price include filter fabric along the full repair length?
- If a new hole opens within a year, what will you do?
Drainage questions by area
Where yard water goes decides where soil leaves. These guides add the local details.
- Pretty Bayou & Robinson Bayou: new sewer and water mains are going in, so settle any yard drain tie-in with the utility crew before backfill. Bid PC26-011 agenda item
- Grand Lagoon, Thomas Drive & Bay Point: Bay County requires temporary erosion controls for shoreline work. LDR 1904(2)
- Lynn Haven & North Bay: Bay County counts 93 repetitive-loss flood properties in Lynn Haven. Bay County LMS
Show sourcesHide sources
- Coastal Erosion Control DesignSource reviewed 2026-10-27
- January 23, 2026 Weekly ReportSource reviewed 2026-10-28
- Bay County Land Development Regulations, Section 1904Source reviewed 2026-10-28
- Bay County Local Mitigation Strategy Plan 2025Source reviewed 2026-10-28
- Tropical Cyclone Report: Tropical Storm Fred (AL062021)Source reviewed 2026-10-28
- Post Tropical Cyclone Report: Hurricane Isaias (NWS Tallahassee)Source reviewed 2026-11-05
- CO-OPS station metadata: 8729108 Panama City, FLSource reviewed 2026-10-28
- Florida ERP Applicant Handbook Volume I, June 28 2024Source reviewed 2026-10-27
- Planning & Zoning | Bay County, FLSource reviewed 2026-10-28
- Land Development Code, Panama City Beach, Section 3.02.05 Site Plans and Construction DocumentsSource reviewed 2026-10-28
- Permits | Bay County, FLSource reviewed 2026-10-28
- Agenda Item Request: Award of PC26-011 Pretty Bayou Improvements Phase 3Source reviewed 2026-10-28