Does the groundwater really move with the tide?

On waterfront sites, yes, with a lag that depends on the soil. It is measured at the site.

Can you just use bigger pumps?

You can try to out-pump the ocean. A cut-off wall is usually cheaper and more reliable.

Does salt water change the concrete?

Yes — cover, mix design and reinforcement protection all change in a marine environment.

What about the neighbor's seawall?

Survey it before you start. Old seawalls are fragile and it will be blamed on you otherwise.

Ground conditions · Tidal & Waterfront Sites

Tidal Sites — The Table Moves Twice a Day

Near the Intracoastal and the coast, the groundwater is tidally connected. It rises and falls twice a day, and a dewatering system designed for a static table will fail on the flood.

Request a preconstruction review Call (954) 807-3208

Send the geotechnical report and the site plan. You get a written read on the water, the excavation and the risk.

Self-perform

Dewatering and support of excavation, in house

Tidal

Deep foundations in tidal environments

Licensed

General contractor, licensed in the state of Florida

Water

The variable that decides the schedule in Florida

Designing for the mean is designing to fail

A tidally influenced water table is not a number, it is a range. Size the system for the average and it drowns twice a day, on a schedule. Everything — pump capacity, cut-off depth, the excavation sequence — is designed against the high water condition, and the tide chart becomes a programming document.

What tidal influence changes

Pump capacity sized to high water, not mean.
Cut-off walls become far more valuable, because they reduce the inflow.
Salt water, which changes corrosion and concrete specification.
Seawall condition next door, which is often old and fragile.
Work sequencing planned around the tide, not only the shift.

How we handle it

01Establish the tidal range and lag at the site, not the published tide.
02Design to high water with the sequence to match.
03Consider cut-off to reduce inflow rather than out-pumping the ocean.
04Survey and monitor adjacent seawalls before starting.
05Specify materials for a marine environment.

Tidal lag is the part that gets missed. Groundwater inland of the seawall does not peak when the surface water does — it lags by hours, and the amount depends on the soil. Measuring it at the site beats reading a tide table for a station a mile away.

FAQ

Common questions

Does the groundwater really move with the tide?: On waterfront sites, yes, with a lag that depends on the soil. It is measured at the site.
Can you just use bigger pumps?: You can try to out-pump the ocean. A cut-off wall is usually cheaper and more reliable.
Does salt water change the concrete?: Yes — cover, mix design and reinforcement protection all change in a marine environment.
What about the neighbor's seawall?: Survey it before you start. Old seawalls are fragile and it will be blamed on you otherwise.

Capabilities

Construction Dewatering

In most of coastal Florida the groundwater sits a few feet below grade. Any excavation deeper than that is an excavation in water until something is done about it, and what gets done determines the program.

Support of Excavation

Support of excavation is the system that keeps the hole open and keeps the ground next to it from moving. On a tight urban site it is the whole job.

Sheet Piling

Interlocking steel sheets driven or vibrated into the ground, giving retention and a groundwater cut-off in one system. In saturated Florida sand that combination is often exactly what the job needs.

Secant & Slurry Walls

Overlapping drilled piles, or a trench supported by slurry and filled with concrete, forming a structural wall that also cuts off groundwater. The answer where sheets will not go.

Auger Cast Piles

A continuous flight auger is drilled to depth and grout is pumped through the stem as it withdraws. The soil is never left unsupported, which is why the method suits saturated Florida sand.

Helical Piles

Steel shafts with helical plates, screwed into the ground with equipment small enough to work inside a building. Capacity is verified by installation torque and the pile can be loaded immediately.

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More ground conditions

Saturated Sand

The most common condition across coastal Florida: clean permeable sand with the water table a few feet down. It excavates easily and it will not stand up wet.

Coquina & Cap Rock

Cemented shell and limestone layers turn up across Florida at unpredictable depths, and they are the reason a method chosen from experience rather than borings goes wrong.

Organic Muck & Peat

Organic soils turn up across inland and former wetland Florida. They compress under load, keep compressing for years, and cannot be improved by compaction.

Next step

Find out what is actually wrong with it.

An inspection, photographs of what we found, and a written scope. If the honest answer is that it can wait another season, that is the answer you will get.

Request a preconstruction review (954) 807-3208