The figureA minimum of 6 ft NGVD29, and the wall must structurally support 7.5 ft. Zoning Code Sec. 3-706.
Two numbers, two meaningsThe 6 ft is the elevation you build to. The 7.5 ft is structural capacity - what the wall must be able to carry. They are not the same requirement and should never be merged.
Mind the datumNGVD29, not NAVD88. The code states the datum explicitly and gives no conversion, and the offset between the two is local. Take it as written and get your datum from your survey.
No maximumUnlike Pompano Beach or Deerfield Beach, Coral Gables sets a floor and no ceiling.
Engineered and specifiedPlans must be designed by a Florida registered engineer, and the wall designed for loads imposed by saturated backfill. Reinforced, pre-stressed or gravity mass concrete - with block or native stone allowed only in water bodies west of LeJeune Road and north of Sunset Road.
The public hearing most people do not expectA seawall or bulkhead is a Class 2 waterfront permit, and the code requires a public hearing before the City Commission before it is approved, with 15 days' published notice and courtesy notice to riparian owners within 1,000 feet. The exceptions that waive the hearing cover mooring piles, residential docks and dock repair - not seawalls. Sec. 109-42(c) and (f). Confirm current practice with Public Works, because this is the code as written.
A biological surveyClass 2 applications require a biological survey and ecological study. Sec. 109-42(b)(5)(e).
The Board of ArchitectsCoral Gables reviews the look of the work. City Architect or Board of Architects approval is on the permit checklist, and the Building Official may not waive it.
The bond, correctly statedA performance bond set by the Public Works Director. The minimum is $1,000 or 25% of the estimated cost, whichever is lesser; the maximum is 100% of the estimated cost. It stays in force at least six months after the approved completion date. Sec. 109-42(e)(3). A separate refundable damage deposit may also be required.
Maintenance is enforceableIt is unlawful to let a retaining wall between your property and a canal deteriorate to the point it encroaches or falls into the canal. Sec. 86-119(b). After notice you have 20 days to remedy or request a hearing, after which the city may do the work and lien the property at 6% interest. Secs. 86-120 to 86-123. The scheduled civil penalty for failure to maintain waterfront improvements is $400.
RecertificationAny mooring structure ten years or older requires certification by a licensed engineer, and re-certification every five years after. Sec. 109-44(b).
Your dock is measured off the wallNo dock more than 5 ft outward from the bank or the seawall, whichever is most restrictive. Sec. 3-702(A). Docks may not be covered or multi-level above grade.
Keep the channel clear75 ft of navigable width south of US-1, 45 ft north of it, and 30 ft in the Mahi Canal. Sec. 3-702(C).
Two permits and a county stampPublic Works issues the Class 2 waterfront permit; Development Services runs the building permit; Miami-Dade DERM approval is required first and its stamp is required on revision re-submittals.