Key Colony Beach seawall repair and replacement

Get to know your waterfront

Key Colony Beach is its own city of 286 acres at mile marker 53.5, surrounded by Marathon. Its 11 canals all run to the ocean side, and most homes sit on one. The island was pumped up from about 97 acres of low ground in the early 1950s, and its first seawalls were cypress timber.

About our City · About Marathon (History) · Monroe County Residential Canals (Google Earth KMZ layer 'Residential_Canals_WGS', linked as 'Google Earth Document with Downloaded Canal Information') · History (1958 letter by Mayor F.P. Sadowski, as published by the city)

Key Colony Beach seawall code, deadlines and history

If the city sends you a seawall notice, the clock starts that day. Ordinance 2026-509, passed unanimously on March 19, 2026, added Code Sec. 6-45 and made seawalls structures the city inspects. KCB Code Sec. 6-45 KCB Commission minutes, March 19, 2026

The building official can extend these dates for documented progress. Plans must be signed and sealed by a Florida engineer, and the city inspects during and after the work. KCB Code Sec. 6-45

Rental owners carry extra risk. Falling short is grounds for "immediate non-refundable revocation and non-renewal" of a vacation rental license or business tax receipt. KCB Code Sec. 6-45

• A Dec. 11, 2025 letter announced citywide marine structure inspections. Owners whose walls needed structural work were asked to call within 30 days. KCB inspection letter
• By March 2026 a commissioner reported the inspections done, with some walls needing immediate attention, including a heavily damaged one on 3rd Street. KCB Commission minutes
• If an owner does nothing, Sec. 5-62 lets the city make the repairs and lien the property. KCB Code Sec. 5-62

What a Key Colony Beach seawall must look like

The commission's view, in Sec. 5-25, is that seawalls suit most of the city best. They are required wherever state or federal agencies allow them. KCB Code Sec. 5-25

Sources: KCB Code Sec. 5-51 KCB Code Sec. 5-50 KCB Code Secs. 5-52 to 5-55

That 5.5 feet sits on an old Coast and Geodetic datum, not NAVD88. Ask your surveyor to convert it and to shoot your neighbors' caps. Read the height guide before you sign off on a cap elevation.

Driving a new wall in front of a failing one breaks the property-line rule, so it takes a variance. In 2021 the planning board heard one for 261 11th Street, with sheet pile about 12 inches out, and the building official expected such requests often. KCB P&Z minutes, July 21, 2021 KCB Code Sec. 5-71

Why so many walls are due at once

The island was built, not found. In the early 1950s, dredges pumped bayside marl and ocean coral sand onto about 97 acres of low island, growing it to almost 400. Canal spoil then raised it to about 6 feet above mean sea level. 1958 Sadowski letter, city history

The first walls were heavy cypress timber, expected to last 20 years. The city's Seawall Owner's Manual says most of today's walls were designed for 30 years, and many are past it. KCB Seawall Owner's Manual

• The typical wall: 6-inch reinforced concrete panels 5 to 8 feet wide, a concrete cap, and tie-back rods to a deadman 10 to 12 feet back. KCB Seawall Owner's Manual
• The manual's four failure modes: joint separation with sinkholes, tie-back failure, toe and berm failure, and cracking at the waterline. KCB Seawall Owner's Manual
• Less than 2 to 3 feet of berm at the toe can let the bottom of the wall kick out. KCB Seawall Owner's Manual
• A wall nonconforming since 1971 may be repaired if, in the building inspector's view, the cost stays within 50 percent of building new. KCB Code Sec. 5-65

Atlantic tides on every canal

All 11 canals, numbered 205 to 219, open to the ocean side and serve 782 parcels. Monroe County canal inventory The county's highest-tide estimate for the old Key Colony Beach gauge is 22.3 inches above mean sea level, against 13.8 inches at Vaca Key on the bay side. county king tide memo

On Oct. 28, 2026, the city relayed a Coastal Flood Warning that expected docks to overtop. City of Key Colony Beach notice Canals 188 and 189 on Clara Boulevard and Coral Lane are filed under Marathon, so confirm which city holds your parcel. county canal street list

Barges, lifts and foam

• Any water-borne construction equipment needs a $50,000 bond before it enters the city. KCB Code Sec. 5-61 Most walls run at least 75 feet, and developed lots often need barge work. KCB Seawall Owner's Manual
• Lift forks may not rise above the cap, and a lift fixed to the cap needs an engineer's certification at 120 percent of lift plus boat weight. KCB Code Sec. 5-43
• The Building Department warns about firms selling foam injection behind walls. Soil work that could affect a wall must be done by a Florida-licensed contractor registered with the city. KCB Building Department notice See foam injection.

What could the work cost?

Key Colony Beach charges $100 for work up to $2,500, then $35 per $1,000 or part, plus a 2.5% surcharge. On an $80,000 contract that is about $2,800 before the surcharge. Starting without a permit costs triple fees plus $500. Ask each bidder if the price covers the $50,000 barge bond, return slabs and the full frontage the code requires.

Calculator ranges come from a 2026 national cost guide and one Key West public bid. None is a quote; your written, itemized scope sets your price.

Find the relevant permits and records

Prepare the questions for the responsible office.

Your Key Colony Beach seawall checklist

Start here, especially if a city notice is already on your desk.

1. Mark the Sec. 6-45 dates

   Count 15, 60 and 120 days from the notice and put each on a calendar. Book the engineer first, since the 60-day plan drives everything after it.

   Code of Ordinances Ch. 6 Buildings, Art. II, Sec. 6-45 Seawall conditions; compliance requirements; enforcement

2. Walk the wall with the city manual

   Look for the four failure modes in the city's Seawall Owner's Manual: sinkholes at joints, tie-back failure, toe loss and waterline cracks.

   Seawall Owner's Manual · Building Department and Code Enforcement

3. Order the right survey

   The city needs a lot survey before construction starts. Ask for the cap height converted from the old datum, plus your neighbors' cap elevations.

   Code of Ordinances Ch. 6 Buildings, Sec. 6-6 Building permit · Code of Ordinances Ch. 5, Art. III Marine Construction and Improvements, Docking of Boats

4. Check registration before any foam work

   A firm injecting foam or soil behind your wall must be Florida-licensed and registered with the city.

   Warning: Soil Amendment Services

5. Ask about the barge bond

   Ask each bidder who posts the $50,000 bond and how long the barge will sit at your lot.

   Code of Ordinances Ch. 5, Art. III Marine Construction and Improvements, Docking of Boats · City of Key Colony Beach Seawall Owner's Manual

Keep planning

Nearby waterfront guides

Marathon: Vaca Key & Boot Key Harbor, Grassy Key, Crawl Key & Coco Plum (east Marathon), Duck Key

View the local guide directory.