New Residence on Tybee Island, GA

Monday, May 19th, 2014 by Allison Rush-Hester

Challenge

A new residence structure was planned for Tybee Island, GA. Tybee Island is one of the coastal barrier islands along the Atlantic Ocean coastline. The entire string of barrier islands along the southeastern U.S. coast serves as a transition zone between the mainland and the ocean.

The project area lies near the eastern edge of the South Atlantic Coastal Plain. The soils encountered are sedimentary in origin and consist of layered marine deposits of sands, silts, and clays. These deposits have since been subjected to successive erosion and re-deposition, by fluctuations of sea levels, storm tides, and winds.

Whitaker Laboratory, Inc. tested the soil by auger cuttings and samples. Near-surface soils on the site consisted of 4 to 5 inches of stone mixed with topsoil. The liquefaction analysis indicated that the encountered sand stratifications present below the groundwater table do not have the potential to liquefy during the design seismic event. Due to the site's location on a barrier island and within close proximity to the ocean, Whitaker provided various options for foundation support. 1. Shallow spread footing foundation elements can be utilized for support of the structure. 2. Treated 12-inch timber piles can be utilized for support of the structure. 3. Utilize helical piers in conjunction with shallow foundation elements.

Solution

Lowcountry Basement installed twenty-eight Helical Piles to support the new homes structure. Helical Piles are designed such that most of the axial capacity of the pile is generated through bearing of the helix blades against the soil. The helical blades are typically spaced three diameters apart along the pile shaft to prevent one blade from contributing significant stress to the bearing soil of the adjacent blade. They are perfect for new construction and any projects built near the coast.