Why is soil washing out from behind my bulkhead, and how is it stopped?
Soil washes out when water moving through, under, over or around a bulkhead carries backfill with it. The usual paths are open joints and torn filter fabric, weep holes without filters, a scoured toe, waves overtopping the cap, and unprotected wall ends. Stopping it means closing the specific path and then restoring the fill; refilling alone usually just feeds the next tide.
Warning signs to look for
- Brown or cloudy water at the base of the wall as the tide falls.
- Fans of sand or soil on the bottom in front of particular joints.
- Soil staining on the wall face below joints, cracks or weep holes.
- The lawn edge pulling away from the back of the cap, or a gap opening along it.
- Erosion at the ends of the wall where it meets a neighbor's wall or a natural bank.
- Filter fabric, roots or pipes showing behind or under the cap.
- Low spots and puddles in the yard that creep closer to the wall over time.
How urgent is it? Slow, ongoing washout is usually a near-term repair rather than an emergency, but it can turn into sinkholes and lost support if it continues, so plan an evaluation soon. Treat it as urgent if holes are opening, the wall is moving, or heavy washout followed a storm.
What Soil Washout Is
Soil washout is the loss of backfill from behind a retaining structure. Key Colony Beach's seawall owner's manual defines the problem plainly as soil from behind the wall escaping into the water, through defective joints or cracked panels. It is slow at first, often invisible from the yard, and it is the process behind most sinkholes behind seawalls.
In Florida the words bulkhead and seawall are used for the same structures, and this page uses both. The U.S. Army Corps of Engineers draws the technical line this way: a bulkhead is a retaining wall whose main purpose is to hold soil in place against light-to-moderate waves, while a seawall is built to protect the land behind it from heavy wave action. Most canal and river walls work mainly as bulkheads, which is why losing the soil behind them is the failure that matters. See Bulkhead vs. Seawall.
Five Ways Soil Leaves a Bulkhead
| Path | How it works | Where to look |
|---|---|---|
| Through joints and cracks | Tide water flows in and out through a gap and carries fill each cycle; Key Colony Beach's manual describes backfill washing away daily this way | Wall face at low tide, staining below joints |
| Through weep holes | Drain holes without a filter behind them pass soil along with water | Staining or sand below weep holes |
| Under the toe | Scour lowers the bottom until fill escapes beneath the wall, as Fort Lauderdale's seawall plan describes | Water depth at the base, missing berm or rock |
| Over the top | Waves or surge spill over the cap and scour the backfill; the Corps guide notes white spray does little damage, but solid green water coming over a structure can erode the ground behind it | Scour channels and bare soil behind the cap after storms |
| Around the ends | Erosion continues around a wall's ends, called flanking, and works back behind it | Wall ends and transitions to a neighbor's wall or bank |
Several Florida conditions speed these up. Tides move water through every opening twice a day. Boat wakes strip the berm at the toe. Fort Lauderdale's plan points out that waves breaking at a wall can erode fill upland of it even when the water does not overtop. Sprinklers and roof runoff that soak the strip behind the wall push water and fines toward the same openings. And filter fabric, once exposed, does not last: the Corps guide warns that sunlight degrades unstabilized fabric quickly.
Wall ends deserve special attention. The Corps guide calls flank protection important because any bulkhead is vulnerable as erosion continues around its ends, and Palm Coast's technical manual requires minimum 10-foot end returns on canal bulkheads unless the wall abuts an existing bulkhead.
How Professionals Find the Leak
Washout is diagnosed by matching evidence on the water side with evidence on the land side. The most revealing time to look is at low tide, after a falling tide has had time to push water and fines out through any opening.
What a Washout Evaluation Usually Includes
- Walking the wall from land and inspecting the face from the water, as Fort Lauderdale's inspectors did for its city walls.
- Noting each joint, crack and weep hole with staining or sediment below it.
- Probing the ground behind those locations for voids and soft spots.
- Measuring water depth along the toe and checking for missing berm or riprap.
- Checking the wall ends and the transition to neighboring walls for flanking.
- Looking for overtopping evidence: scour channels, debris lines and bare soil behind the cap.
- Reviewing where yard, roof and pool water drains, and whether pipes pass through the wall.
- Recommending a diver where joints or the toe below water cannot be seen.
Typical Ways Washout Is Stopped
Each path has its own fix, and most walls with washout have more than one path. The approaches below are described generally; a contractor or engineer chooses the combination for the wall and site.
- Joint and crack repair. Key Colony Beach's manual describes sealing vertical slab joints with filter fabric, and Fort Lauderdale's plan calls routine sealing of joints and cracks key to avoiding long-term settlement.
- Filtered drainage. Cleaning weep holes and adding weep filters, or retrofitting tidal valves that let water drain out while holding back fines.
- Toe protection. Added berm, riprap, sand-cement bags, concrete-filled mats or extended sheet piling, depending on the hydraulic conditions at the wall.
- Overtopping protection. Raising the wall or cap where permitted, or armoring the ground behind the cap. Discussing revetments and similar structures, the Corps guide describes choosing a height above expected wave runup, or adding an overtopping apron, as ways to limit overtopping damage.
- End returns. Adding or extending returns where the wall ends, tied into the neighboring wall or the bank.
- Restored backfill. Once the paths are closed, replacing lost fill; the Corps guide notes granular material is preferred for bulkhead backfill.
- Surface drainage. Grading, swales or berms that keep yard runoff from flowing to the wall.
Some Fixes Need Engineering and Permits
Raising a wall, adding returns, placing rock in the water or rebuilding large sections usually involves local building permits and, often, state and federal authorizations. Some cities require a permit for any seawall repair, so check the Florida seawall permits overview and your building department before work starts.
What Happens If Washout Continues
Washout tends to compound. Voids grow behind the wall until the surface collapses into sinkholes. Slabs, walkways and pool decks lose the soil that supports them. The soil that tie-rod anchors bear against can be lost or loosened, and Fort Lauderdale's plan notes that tiebacks rely on that soil's passive resistance. Fort Lauderdale's plan notes that once fill escapes and the ground behind a wall settles, the overall stability of the wall suffers. The soil itself ends up on the bottom in front of the wall, so the land you are losing is visible at low tide if you know where to look.
Keeping Backfill Where It Belongs
Routine Habits That Reduce Washout
- Keep weep holes clear and report any that pass soil rather than clear water.
- Keep the strip behind the wall planted. UF/IFAS Florida-Friendly Landscaping recommends a low-maintenance zone at least 10 feet wide along the water, and swales or berms where possible to keep stormwater out of the water body.
- Direct roof, pool and irrigation water away from the wall rather than toward it.
- Watch the ends of the wall and the joint with your neighbor's wall after every major storm.
- Replace lost toe rock or berm before scour reaches the bottom of the panels.
- Slow down along seawalled canals to reduce wake energy at the toe.
- Have joints and filter fabric checked during routine inspections.
Who Handles Washout Repairs
If your property is in Duval, St. Johns, Nassau, Clay, Flagler or Putnam County, Barefoot Marine Construction, which owns and operates Florida Bulk Head, takes the request directly. The work follows five steps: Request a Quote, Site Assessment, Plan & Permit, Build or Repair, and Protect Your Property. Low-tide photos showing where staining or sediment appears, keyed to panel counts, help the Site Assessment start in the right place.
For the rest of Florida, Florida Bulk Head is building a partner network and accepts inquiries now. No partners are confirmed, and matching depends on contractor availability. Use the Seawall Health Check to log what you see, then Find a Contractor to see how your area is handled.
What you can safely do now
- At low tide, photograph the wall face and the water at its base from a safe spot on land, noting where staining or sediment appears.
- Identify the joints or weep holes involved by counting panels from a fixed point such as a corner or the dock.
- Point downspouts, pool discharge and sprinklers away from the strip right behind the wall.
- Keep turf or low plants along the wall rather than bare soil, and hold off on adding loose fill that will only wash out.
- Record changes after high tides, heavy rain and busy boating weekends, with dates.
Leave structural work, excavation behind the wall and anything in the water to licensed professionals.
Frequently asked questions
Is soil washout the same as erosion?
It is a kind of erosion. Erosion of an open bank happens at the surface where waves strike it. Washout behind a bulkhead happens inside and under the structure, through openings the wall was supposed to keep soil-tight, which is why it can go unnoticed until a hole appears.
Should I keep adding fill behind the wall?
Not as a fix. New fill goes out the same way the old fill did if the path is still open, and repeated filling can hide how much has been lost. Have the path found and closed first, then restore the backfill as part of the repair.
Can washout be fixed without replacing the bulkhead?
Often, yes. Joint sealing, filtered weep holes, toe protection, returns and restored backfill are all repairs to an existing wall. Replacement comes into the discussion when washout is widespread and the wall itself is failing, such as with heavy corrosion, a moving wall or inadequate embedment.
Why is soil washing out at the end of my wall?
Wall ends are a common weak point. If a return is short, missing or not tied into the neighboring wall or bank, water can work around the end and behind the wall. The Corps guide calls this flanking, and Palm Coast's standards require 10-foot minimum returns on canal walls unless they abut an existing bulkhead.
Do weep holes cause washout?
They can if nothing filters them. Weep holes are there to relieve water pressure behind the wall, and blocking them creates other problems. The fix is a proper filter behind or in the weep, such as filter fabric, graded stone or a retrofit tidal valve, not sealing the hole.
Does washout repair need a permit?
Often, yes. Some cities require a permit for any seawall repair; Key Colony Beach's manual, for example, states that all repairs there need a city permit. Work like toe rock in the water, raising a wall, rebuilding sections or adding returns usually involves at least a local building permit and sometimes state or federal approval. Confirm with your building department or the contractor handling the work before anything starts.
Sources and references
- Seawall Owner's Manual — City of Key Colony Beach Building Department. Accessed November 2, 2026. Erosion definition, joint separation with daily tidal washout, joint sealing with filter fabric, drainage tips.
- Low Cost Shore Protection: A Guide for Engineers and Contractors (1981) — U.S. Army Corps of Engineers, via the U.S. Government Publishing Office. Accessed November 2, 2026. Bulkhead and seawall definitions, flank protection, filters and drain holes, backfill and fabric durability. Older guidance, cited for general mechanisms.
- City of Fort Lauderdale Seawall Master Plan: Summary Report — City of Fort Lauderdale (prepared by BCC Engineering, 2018), hosted by the Southeast Florida Regional Climate Change Compact. Accessed November 2, 2026. Section 2.5 wave erosion of fill; sections 4.6 to 4.8 scour protection, tidal valves and joint sealing.
- City of Palm Coast Technical Manual, Section V: Engineering Design Standards — City of Palm Coast. Accessed November 2, 2026. Drawing 1100.G end return detail (dated October 1, 2009, revised January 2010).
- Principle 9: Protect the Waterfront — UF/IFAS Florida-Friendly Landscaping Program. Accessed November 2, 2026. Low-maintenance zone along the water and swales or berms to keep stormwater out.
Regulations, programs and conditions change. Always confirm requirements with the agency that has jurisdiction over your property.