Seawall Construction in Camachee Island

A seawall is designed around the energy it absorbs, so the design starts with the water rather than with the wall.

Camachee Island is a compact waterfront community built around Camachee Cove Yacht Harbor, just inside the St. Augustine Inlet on the Tolomato River. It is a boating address first and foremost — the marina is the organising feature, and most properties here were bought with vessel access as the primary consideration.

Frontage is largely hard-edged and purpose-built, oriented around the harbour and the channel serving it. This is one of the more engineered shorelines in the county, with less natural bank and marsh than its neighbours and correspondingly more existing structure to assess and maintain.

The cove itself is relatively protected, which is the point of it. Energy increases sharply towards the Tolomato and the inlet approach, where tidal current becomes a serious consideration. Properties on the outer edge of Camachee face materially different conditions from those tucked inside the harbour.

Full salt exposure. Hardware, fasteners and embedded reinforcement all corrode faster here than on the fresher inland reaches, so specification is a service-life decision rather than a detail. Tidal range is significant. That matters twice over: it drives a large volume of water in and out through any opening in a wall, and it makes a fixed-only dock awkward to board at the bottom of the tide.

Largely made ground and engineered fill associated with the development of the island and harbour, over native sands. Fill character and depth vary, and knowing what is actually under a given property matters more here than in areas with undisturbed native soil. For a seawall it drives section selection, how much toe protection the wall needs, and where the cap has to sit to limit overtopping.

A new seawall on Tolomato River, Intracoastal Waterway and St. Augustine Inlet has to answer all of these. The ones involving scour and overtopping are the ones most often left out of a cheap design.

• Toe scour on the outer frontage where inlet-driven current runs hardest
• Deterioration of ageing harbour-side structures built when the community was developed
• Soil loss through joints in fill that has limited cohesion to begin with
• Salt exposure driving corrosion in hardware and reinforcement
• Concentrated wake and prop wash in the harbour approach

A seawall is designed around the energy it has to absorb, and that is why we will not quote one by the foot over the phone. The cove itself is relatively protected, which is the point of it. Energy increases sharply towards the Tolomato and the inlet approach, where tidal current becomes a serious consideration. Properties on the outer edge of Camachee face materially different conditions from those tucked inside the harbour.

On Camachee Island frontage that drives four things: the section selected, how deep it is embedded, whether toe protection is needed and how much, and where the top of the wall sits relative to design water levels.

• Fetch and wake exposure specific to your frontage on the Tolomato River
• Embedment depth, with an allowance for scour rather than for soil load alone
• Toe protection sized for the energy the wall will reflect back into the water
• Cap elevation and freeboard, set to limit overtopping
• Tieback spacing and anchor placement outside the active soil wedge

A vertical wall reflects wave energy downward into the water at its own base, and that reflected energy excavates the material the wall is embedded in. The wall undermines its own foundation, continuously, and none of it is visible from the top.

Outer Camachee frontage facing the Tolomato and the inlet approach takes genuine hydraulic loading, and toe protection there is warranted. Inside the cove, conditions are materially gentler and a wall designed for the outer frontage would be over-specified.

If you are comparing estimates for Camachee Island and one of them has no toe protection on exposed frontage, that is the question to ask before you compare the totals.

Full salt exposure. Hardware, fasteners and embedded reinforcement all corrode faster here than on the fresher inland reaches, so specification is a service-life decision rather than a detail. We build vinyl and concrete seawalls, and the choice turns on exposure, what sits behind the wall, and how long you intend to own the property.

The important qualifier for vinyl is that wave loading is a larger demand than soil retention, so the section has to be selected for it. A profile adequate on sheltered water is not automatically adequate here. The full construction process is here.

A new seawall here is also a soil-retaining structure, so the bulkhead side of the problem does not go away. Much of the bulkhead work at Camachee is on structures that have been in place since the community was built, retaining fill rather than native soil. Full detail: bulkhead construction in Camachee Island and bulkhead repair.

A new wall is the natural moment to resolve a dock tie-in properly rather than working around it. The constraints on this frontage:

More at dock construction in Camachee Island.

• Working within an established marina environment with vessel traffic and berthing constraints
• Strong current on the outer frontage, loading piles and scouring foundations
• Pile penetration through variable fill to reach competent bearing

Putting that together for a new seawall here:

Camachee properties benefit from an inspection that establishes the condition of existing structures and what is under them, since so much of the shoreline is engineered and ageing together. Treatment then differs sharply between inner-harbour and outer-river frontage.

Compact lots in an established marina community, with the practical advantage that water access is excellent and the practical constraint that land access and laydown space are limited. Coordination with harbour operations is usually part of the job.

A new seawall is reviewed as new construction, and the toe protection it needs is part of the proposal rather than an afterthought added later.

Proximity to the inlet and the ICW channel puts navigation considerations at the front of review, and work within or adjacent to an operating marina brings its own coordination requirements.

Requirements are revised periodically. Treat this as orientation and confirm current requirements with each reviewing agency before planning work. We handle permitting on the projects we build, and agency review is normally the longest item in the schedule.