Bridge Contractor South Carolina

South Carolina is a state of creeks, rivers, millponds and tidal marsh, and a great many homes, farms and plantations sit on the far side of one of them. Foundation Masters designs and builds those crossings: private drives, development entrances, farm and timber access, and the replacement of spans that were never built for what crosses them today.

We are a design build firm, which means the investigation, the drawing and the structure all come out of one shop instead of three. Jeff Earl founded Foundation Masters after two decades in deep foundations, earth retention and structural repair, and a licensed professional engineer seals the plan set before anything gets driven.

South Carolina sits inside a Southeast footprint that also covers Florida, Georgia, North Carolina, Tennessee, Alabama and Mississippi. Everything is indexed on the bridge contractor hub.

The 1886 Earthquake and the Ground Under the Lowcountry

On the night of August 31, 1886, an earthquake estimated at magnitude 7 struck near Summerville, about 25 kilometers northwest of Charleston. It is still the most powerful and destructive earthquake on record in the southeastern United States. About 100 people died, Charleston was nearly leveled, railroad tracks buckled, a trestle shifted about two meters, and dams broke and flooded farms and roads. Shaking was felt from Maine to Florida.

A great deal of that damage came from the ground, not the shaking itself. Across the Lowcountry the saturated sand liquefied. It lost its strength and flowed like water, and small volcano shaped sand blows erupted across fields, roads and yards. Buildings, roads and bridges sitting on that sand settled, tilted and cracked.

That is the part a bridge designer cannot ignore around Charleston, Summerville, Mount Pleasant and the Sea Islands. Loose saturated sand near the surface is exactly the material that liquefies. A shallow footing sitting in it is riding on something that can turn to liquid. The answer is to carry the abutments on piles driven through the loose sand into denser material below, and to detail the connections so the deck stays tied to its supports when the ground moves. That starts with soil borings that tell us how deep the loose layer goes.

Four Kinds of Ground Between the Mountains and the Marsh

The Fall Line runs right through Columbia, where the Piedmont hills end and the Coastal Plain begins. Above it, a pile is usually looking for rock. Below it, there is no rock in reach and the questions change completely.

The FM-H20 Fire Truck Rated Bridge

A loaded pumper weighs somewhere north of fifteen tons. The pickup that has been crossing your bridge for years weighs three. Those are not the same question, and on a long private drive in rural South Carolina there is usually no second way in. The FM-H20 is the bridge we build so that the answer is yes before anybody has to ask.

Steel girder, beam plate, abutment and 6×6 rail details from a sealed FM-H20 drawing set. Signed and Sealed

Full detail on the FM-H20 fire truck rated residential bridge page. Starting price is around 3,300 dollars per linear foot.

Foundations: The FM-PP30 Driven Pipe Pile

Four FM-PP30 piles carry each abutment. Three inch schedule 40 pipe, thirty tons apiece, driven with a pneumatic hammer by our own crews. Driven rather than hydraulically pressed matters on a soft or narrow bank, because a pressed pile has to react against structure that is not there yet and a driven one does not.

In the Upstate the pile works through the saprolite and is driven to refusal on rock, which can sit at very different depths from one abutment to the other. Below the Fall Line there is no rock to find, so the pile is driven until it develops capacity in the sand and clay. In the Lowcountry it also has to get through the loose saturated sand that could liquefy in an earthquake, so the capacity comes from the denser ground underneath. Same system, set to a very different stopping point depending on the county.

This is also where the pipe pile approach earns its place over a drilled shaft on a residential job. The rig is small enough to work on a creek bank or a marsh edge, and driving the pile tells you what the ground is doing as you go.

The 2015 Flood and the Crossings Below Small Dams

In early October 2015 a stalled storm system dropped historic rain across South Carolina. Mount Pleasant recorded nearly 27 inches over four days. Catastrophic flooding led to the failure of 51 dams, many of them small private and neighborhood ponds, and more than 15 deaths.

South Carolina has thousands of millponds and small impoundments, and a lot of private crossings sit on the creek just below one. When an upstream dam lets go, the crossing below it sees a flood far bigger than the creek would ever produce on its own. We look upstream before we size a crossing. If there is a pond above it, the bridge gets a clear span with the steel high enough to pass that water, abutments set back from the channel, and sheet pile protecting the fill.

Building in the Lowcountry Marsh

South Carolina has eight coastal counties: Beaufort, Berkeley, Charleston, Colleton, Dorchester, Georgetown, Horry and Jasper. Work in the coastal critical areas there, meaning coastal waters, tidelands, beaches and the beach and dune system, needs a critical area permit from the state Bureau of Coastal Management, in addition to any federal authorization through the Corps of Engineers.

The engineering is familiar to us from Florida. Marsh mud has almost no strength, the water table is at the surface, and hurricane surge and scour govern the design more than the truck on the deck. Piles go deep, the deck is tied down to the girders and the girders to the abutments, and the approaches are built so a high tide does not wash them out from behind.

What We Build in South Carolina

South Carolina Service Areas

Already have a builder lined up? We will do the investigation, the design and the sealed set and hand it to them.

South Carolina Bridge FAQs