Ground conditions · Karst & Sinkhole Risk
Karst — Voids You Cannot See
Much of central Florida sits on limestone that groundwater has dissolved over time, leaving voids and raveling zones. It is the one condition where the investigation matters more than the design.
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
Dewatering can be the trigger
Lowering the water table in karst can remove the support holding raveled soil in place and initiate a collapse that was not going to happen otherwise. This is the condition where the act of preparing the site creates the hazard, and it is why karst is a specialist geotechnical question before it is a construction one.
How the risk is handled
- Geophysical survey to find anomalies borings would miss entirely.
- Borings targeted at the anomalies, not on a convenient grid.
- Grouting to fill voids and stabilize raveling zones.
- Foundations designed to span a potential void, not just to bear.
- Dewatering minimized and staged, because rapid drawdown is the trigger.
How we handle it
- 01Insist on geophysics before excavation planning in known karst.
- 02Target investigation at anomalies rather than a uniform grid.
- 03Grout where the investigation shows it is warranted.
- 04Design foundations for a span condition where risk remains.
- 05Stage and limit drawdown, and monitor continuously.
This is the ground condition where we will most readily tell an owner to spend more on investigation before spending anything on construction. Geophysics is cheap next to a collapse, and it is the only tool that looks between the borings.
Said plainly
Where we stop
In known karst we will not price excavation from borings alone. If the geophysical survey has not been done, that is the first item, and we will say so even when it delays the job.
FAQ
Common questions
- Can dewatering cause a sinkhole?
- It can. Rapid drawdown in karst can trigger a collapse, which is why it is staged and monitored.
- Do borings find voids?
- Only by luck. Geophysics looks between the borings, which is the point.
- Can voids be grouted?
- Yes, and it is common practice where the investigation shows it is warranted.
- Is central Florida all karst?
- Much of it is karst-prone. The county and the geotechnical engineer determine the risk for your site.
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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.