Seawall replacement in Key Largo

When replacement makes sense

Replacement is the answer when panels are cracked through, the wall leans, repairs would cost more than half of a new wall, or the wall is too low for your city's new standard.

• Panels cracked through or leaning
• Repeated sinkholes despite repairs
• A city notice to raise or rebuild
• Planned dock or lift work that needs a sound wall

Where a seawall is allowed at all

Monroe County allows vertical seawalls only to stabilise severely eroding shorelines on man-made canals, channels or basins, and never on open water. Lawfully existing walls may be repaired or replaced on the same footprint, the yard behind must sit at least 6 in below the top of the wall, and riprap goes at the toe wherever feasible.

A replacement wall is built to the current height from the start, so the panels, piles and cap are sized for it.[1]

Mangrove fringes shape the design

Where a Key Largo shoreline has a mangrove fringe 10 ft wide or more, a T or L dock with a walkway perpendicular to the shore is the primary design. Riprap and walls go landward of existing mangroves wherever feasible, and a walkway through mangroves is limited to 4 ft.

New walls often get riprap at the toe in the same mobilisation, which saves a second trip.[1]

What makes Key Largo different

The special exception application asks owners to describe the submerged lands the dock crosses, such as sand, seagrass or coral, and the minimum extra length needed to reach adequate water depth. The site plan must be prepared by a Florida registered architect, engineer or landscape architect and show the mean high water line and shoreline setbacks.[2]

Sanctuary, seagrass and manatees

Projects inside the Florida Keys National Marine Sanctuary needed prior Sanctuary approval under SPGP VI. The same permit let boat lifts and minor structures in Monroe County go into existing boat slips without a seagrass survey. All in-water work follows the state manatee conditions.[3][4]

Permits in Key Largo

• Monroe County Planning and Environmental Resources Department: Dock length special exceptions under County Code section 118-12(m)(15).
• Florida Keys National Marine Sanctuary: The Sanctuary starts at mean high water, so Key Largo canal and bay work is inside it; SPGP VI required its prior approval.
• Florida DEP or South Florida Water Management District: State permit or exemption, which Monroe County needs to see before it issues a Notice to Proceed for docks, seawalls and ramps.
• US Army Corps of Engineers, Jacksonville District: Federal permit, also required before the County's Notice to Proceed.

What a seawall replacement involves

A Florida engineer designs the wall to the site's soil, water depth and the local top elevation. Most replacements go in front of the old wall, which stays in place as backing, because removing it can undermine the yard.

1. Survey and engineered drawings
2. DERM, city and state approvals
3. Turbidity barrier and manatee watch in the water
4. New panels or sheet piles, tiebacks and cap
5. Backfill, drainage and yard restoration

How far out can the new wall go?

Florida Statute 403.813 exempts restoring a seawall at its previous location, upland of it, or within 18 inches waterward of it. Miami-Dade's short form and the federal SPGP VI use the same 18 inch line, measured wet face to wet face, and need no seagrass survey within it.[9][8][3]

Federal permits

Under SPGP VI, the Florida DEP could verify the federal Army Corps authorisation for qualifying seawall work along with the state decision. That permit's stated expiration date was 27 July 2026, and we have not been able to confirm a replacement, so for each job we confirm the federal route with the agencies before we file.[3][10]

Working around manatees

Permits attach the state's Standard Manatee Conditions: all in-water work stops if a manatee comes within 50 ft, and resumes only once it has moved beyond 50 ft or 30 minutes pass without it reappearing. Turbidity barriers must not entangle or block manatees.[4]

Frequently asked questions