Sinkholes and soil loss behind a bulkhead on Mobile Bay: trace the leak

Yes. Treat it like an open hole. Keep children, pets and mowers away. Mark it with cones or tape and photograph its size each day.

Find the path the soil takes. A contractor will check these points.

• Joints between panels, especially near the base.
• Weep holes and drain pipes that no longer flow.
• Gaps where the wall meets a dock, stairs or neighboring wall.
• Runoff from gutters or paving that drains toward the wall.

One simple test is to watch the wall at a falling tide. Muddy water running out of a joint shows where the soil goes. Photograph it, with the time and tide, for the contractor.

Water trapped behind a wall pushes on it and carries soil away. Good drainage lets that water out slowly through filter fabric and weep holes, without soil.

Surface water matters too. Routing downspouts and yard runoff away from the wall cuts the load. Ask a contractor to check drainage as part of any repair.

1. Stop the leak: seal joints, replace filter fabric, clear or add drains.
2. Rebuild the void with compacted fill or injected material.
3. Restore the surface with sod, pavers or concrete.
4. Recheck after the next high water and a heavy rain.

The foam injection page covers one fill method. The cap and panel repair page covers the joints.

Sometimes the water comes from a road, a ditch or a neighbor's yard. Mobile County's stormwater plan says runoff problems are reported to (251) 574-6511. Mobile County Stormwater Management Program Plan

Photograph the flow after a rain, with the time. A contractor can then aim the fix at the true source, not only at the hole it makes.

• Cone off the area and keep mowers away.
• Do not dump loose fill in the hole; it can wash out and hide the size of the void.
• Photograph the hole with a tape measure, daily for a week.
• Move downspouts and sprinklers away from the wall.

A written log helps. Note the date, the tide, rain in the last day and whether the hole grew. A contractor can use that log to find the cause faster.

1. The joints and base of every panel along the wall.
2. Weep holes, drain pipes and filter fabric where they are visible.
3. Where dock posts, stairs or pipes pass through the wall.
4. How surface water from the yard reaches the wall.

Ask for photos of each finding. The assessment page lists what a full report should include.

Angi lists soil stabilization at $120 to $270 per linear foot. ^[7] A Texas contractor lists drainage at $10 to $20 per foot and site preparation at $20 to $50. ^[12]

An Alabama contractor says drainage pipes and filter fabric add $15 to $30 per foot. ^[19] These are listed prices, not quotes. See the cost guide.

Often yes, especially in a flood zone. Refilling or regrading behind a wall counts as development on a flood-zone parcel in Mobile. The city lists filling and grading among the work needing a permit. Build Mobile flood permit

Mobile treats shaded X zones like the 100-year floodplain, and fill there needs an engineer's no-rise certification. Mobile land disturbance guide Minor home repair is exempt from a land disturbance permit below set limits, but clearing in a flood zone is not. Mobile City Code Sec. 17-8

Mobile County's engineering rules say fill in an A zone with no floodway cannot raise the base flood by more than 1.0 foot. Mobile County engineering requirements Call Engineering at (251) 574-8595. Mobile County Engineering

Call the permit offices and ask about emergency authorization. For an unacceptable hazard or serious loss of property, the U.S. Army Corps of Engineers (the Corps) can approve work at the first phone call. Corps emergency permit ALGP-15

ADEM can approve emergency action without notice, effective for up to 120 days. ADEM rule 335-8-1-.07 Keep photos and bills. The storm guide lists the records to keep.

Sources: Build Mobile website Mobile County Inspection Services Dauphin Island Town Hall Bayou La Batre City Hall

On Dauphin Island, a lot on or near water needs a Town Coastal Use Permit as well. Dauphin Island Ordinance 105 The Corps and State Lands apply wherever work touches the water line.

Watch the spot through at least one stormy season. Re-measure after heavy rain and after the next high water. If the ground stays level, the leak is likely closed. If it drops again, call the contractor back and ask what changed. Keep the log with your wall records.

Water levels here swing hard. In Sally, north winds pushed water out of the bay. The Coast Guard Sector Mobile gauge dropped 10.6 feet in less than a day. NHC Sally report

Zeta flooded the northeast bay by 7 to 9 feet. NWS Mobile Zeta report See the Hollinger's Island guide and the Coden guide.